Douglas J. Mudgway

 1957–1997

ink

NASA

SP-2001-4227

Douglas J. Mudgway

e,

a
NASA SP-2001-4227

Uplink-Downlink

A History of the Deep Space Network

1957–1997

Douglas J. Mudgway

The NASA History Series

National Aeronautics and Space Administration

Office of External Relations

Washington, DC 

2001
This book is dedicated to the memory of

Nicholas A. Renzetti

1914–1998

Throughout his entire career at JPL (1959-1996),

Nicholas A. Renzetti brought the strength and

dynamism of his own character to the Deep Space

Network. Some of it passed to all of those he touched

and to every task he undertook. Due in no small

part to his continued advocacy, there exists a continuous record of the technical achievements of the

Network from its inception to 1997, in the form

of the “TDA Progress Reports” series. He gave rise,

also, to many other publications that reflected the

breadth of activity in which the Network engaged.

For many years, Renzetti envisioned a project that

would distill the essence of materials collected into

a single book-length narrative covering the full story

of the Deep Space Network—scientific, technical,

operational, personal, and political. My pleasure at

having undertaken the task is tempered only by my

regret that he was unable to see it completed.

Douglas J. Mudgway

Sonoma, California
Contents

iii Dedication

xv Foreword 

xix Acknowledgments

xxi Preface

xxvii Introduction

xxix The Solar System

xxix Size and Composition

xxxi Terrestrial Planets

xxxi Jovian Planets

xxxii Inner and Outer Planets

xxxii Asteroids

xxxii Comets

xxxiii Earth and Its Reference Systems

xxxiv Earth Motions

xxxv Time Conventions

xxxv Interplanetary Trajectories

xxxvii Deep Space Communications

xxxvii Bands and Frequencies

xxxviii Doppler Effect

xxxviii Cassegrain Focus Antennas

xxxix Uplink and Downlink

xl Signal Power

xl Coherence

xli Decibels

xliii Modulation and Demodulation

xliv Spacecraft Radio System

xliv An Essential Part of the Answer

Chapter 1—Genesis: 1957–1961

2 Goldstone, California

7 The Pioneer Lunar Probes

12 The Echo Balloon Experiment

15 The Venus Radar Experiment

16 Research and Development Antenna

18 Washington, DC

20 Woomera, Australia
23 Johannesburg, South Africa

26 Endnotes

Chapter 2—The Mariner Era: 1961–1974

30 The Mariner Era Mission Set

33 The Ranger Lunar Missions

36 Mariner Planetary Missions

37 Mariner 1962

39 Mariner 1964

41 Mariner 1967

42 Mariner 1969

45 Mariner 1971

46 Mariner 1973

48 Pioneer Interplanetary Missions

50 Pioneer Jupiter Missions

52 Surveyor Lunar Lander Missions

54 Lunar Orbiter Missions

56 Apollo Missions

59 The Deep Space Instrumentation Facility (DSIF)

61 The Facility (DSIF) Becomes a Network (DSN)

61 L-band to S-band

62 Improvements for the Mariner Mars Missions

64 The Need for a Second Network

66 Larger Antennas are Needed

70 Incremental Improvements in the Network

72 Flight Project Requirements Become Formalized

73 The DSN Becomes a Multimission Network

75 Openings and Closings

78 Looking Back

79 Endnotes

Chapter 3—The Viking Era: 1974–1978

82 The Viking Era Mission Set

84 The Network

87 Network Operations

87 The Helios Mission

91 The Viking Mission

vi

Uplink-Downlink: A History of the Deep Space Netw
107 The Voyager Mission

113 Pioneers 6–11

116 Pioneer Venus

119 Network Engineering and Implementation

119 The DSN Mark III System Design

121 Implementation for Viking

123 DSN Mark III-75 Model

125 The 64-meter Stations

129 The 26-meter Stations

130 High-Power Transmitter

132 Mars Radar

133 The Introduction of X-band

135 The 64-meter Antenna Problems

137 DSN Mark III Data System Project

141 Mark III Data System (MDS) Implementation

145 DSN Mark III-77 Model

146 DSN Mark III-77 Telemetry System

148 DSN Mark III-77 Command System

150 DSN Mark III-77 Tracking System

151 DSN Mark III-77 Ground Communications

151 DSN Mark III-77 Arraying Capability

153 DSN Mark III-77 Decoding Capability

155 The 26-meter Antenna S-X Conversion Project

159 Overview

160 Endnotes

Chapter 4—The Voyager Era: 1977–1986

166 The Voyager Era

166 Deep Space Missions

169 Earth-Orbiting Missions

171 Network Operations

171 Prime Missions

171 Voyager at Jupiter

177 Voyager at Saturn

190 Venus Balloon/Pathfinder

193 Voyager at Uranus

202 Uranus Encounter

206 Extended Missions

Contents
206 Helios

207 Viking at Mars

211 Pioneers 6–9

212 Pioneers 10, 11

215 Pioneer 12 (Venus Orbiter)

216 Highly-elliptical Orbiters

216 ICE

219 AMPTE

221 Reimbursable Missions

224 Network Engineering and Implementation

224 New 34-meter High-Efficiency Antennas

226 The 64-meter to 70-meter Antenna Extension

230 Rehabilitation of DSS 14 Pedestal

233 DSS 14 Azimuth Radial Bearing

233 DSS 43 Pedestal

234 Antenna Performance Upgrade

236 Microwave Design Considerations

237 Kicker Braces

238 Subreflector

238 Surface Panels

239 Madrid Site Implementation

240 Canberra Site Implementation

240 Goldstone Site Implementation

242 Networks Consolidation

246 Mark IVA Implementation

251 Signal Processing Centers

253 Mark IVA Network Operations Control Center

255 Mark IVA Ground Communications Facility

255 DSN Mark IVA System Upgrades

255 Mark IVA Telemetry

258 Mark IVA Command

263 Mark IVA Tracking

265 An Abrupt Transition

266 Endnotes

Chapter 5—The Galileo Era: 1986–1996

272 The Galileo Era 

272 A Defining Moment 

viii

Uplink-Downlink: A History of the Deep Space Netw
273 Mission Set 

274 Overview

276 Network Operations 

276 Deep Space Prime Missions

276 The Comet Halley Missions

277 Giotto

279 Phobos

283 Background for Magellan

285 Magellan Mission to Venus

288 Voyager at Neptune

294 Background for Galileo 

299 Galileo Mission to Jupiter 

319 Background for Ulysses

324 Ulysses Solar Mission

326 Background for Mars Observer

327 Mars Observer Mission

330 Deep Space Extended Missions

330 The Pioneer Missions

331 International Cometary Explorer (ICE)

331 Voyager Interstellar Mission

333 Earth Orbiter Missions

333 General

335 Emergency Mission Support

337 Network Engineering and Implementation

337 The 70-meter Antennas 

338 Elevation Bearing Failure

340 Gearbox Rehabilitation

341 Subreflector Drive Problems

343 Interagency Arraying

343 Parkes-Canberra Telemetry Array 

348 VLA-Goldstone Telemetry Array 

354 The X-band Uplink

358 Block V Receiver

359 The DSN Galileo Telemetry (DGT) Subsystem

371 Beam Waveguide Antennas

383 Signal Processing Center Upgrade Task

383 Background

383 Signal Processing Centers Upgrade

385 SPC Telemetry

Contents
388 SPC Command

390 SPC Tracking

393 Network Operations Control Center

394 Ground Communications Facility

398 A Successful Conclusion

399 Endnotes

Chapter 6—The Cassini Era: 1996–1997

408 The Cassini Era

408 Winds of Change

409 The Cassini Era Mission Set

410 Deep Space Missions

410 General

410 Galileo

410 Ulysses

410 Voyagers 1 and 2

412 Pioneer 10

412 Near-Earth Asteroid Rendezvous

413 Mars Global Surveyor

421 Mars Pathfinder

428 Cassini

434 Earth-Orbiting Missions

434 General

435 Space VLBI Observatory Program 

437 The Network

437 Complexes and Antennas

440 Ka-band Downlink

445 Orbiting VLBI Subnetwork

450 Emergency Control Center

453 Other Aspects

454 Endnotes

Chapter 7—The Advance of Technology in the Deep Space Network

458 The DSN Technology Program

459 The Great Antennas of the DSN

467 Forward Command/Data Link (Uplink)

468 Return Telemetry/Data Link (Downlink)

x

Uplink-Downlink: A History of the Deep Space Netw
469 Low-Noise Amplifiers

472 Phase-Lock Tracking

472 Synchronization and Detection

473 A Digital Receiver

474 Encoding and Decoding

477 Data Compression

478 Arraying of Antennas

483 Radio Metric Techniques

483 Doppler and Range Data

485 Timing Standards

486 Earth Rotation and Propagation Media

486 Radio Science

487 VLBI and Radio Astronomy

489 The Global Positioning System

489 Goldstone Solar System Radar

492 Telecommunications Performance of the Network

494 Cost-Reduction Initiatives 

496 Ka-band Development

498 Other Technologies

498 Optical Communication Technologies

499 DSN Science

Chapter 8—The Deep Space Netwrok as a Scientific Instrument

502 The TDA Science Office 

507 Radio Science

511 Celestial Mechanics

513 Solar Corona and Solar Wind

514 Radio Propagation and Occultation

517 Relativistic Time Delay

518 Gravitational Waves

521 Radio Astronomy

523 International Cooperation

524 Tidbinbilla Interferometer

525 Orbiting VLBI

525 Host Country Program

526 Cross-Support Agreements

526 Guest Observer Program

526 Antenna Utilization for Radio Astronomy

Contents
528 The DSN Also Benefits

529 Significant Advances

533 Search for Extraterrestrial Intelligence (SETI)

541 Crustal Dynamics

550 Planetary Radar

564 Asteroids

566 Radar Astrometry

567 Renaissance

569 Significant Events

572 Endnotes

Chapter 9—The Deep Space Network as an Organization in Change

582 In the Beginning (1958 to 1963)

582 Background 

584 The Rechtin Years

594 The Formative Years (1964 to 1994) 

594 A DSN Manager for Flight Projects

596 The Space Flight Operations Facility

601 The Bayley/Lyman Years

606 The Dumas/Haynes Years

610 The JPL Strategic Plan: 1994

612 Birth of the TMOD

615 Reinventing the Future (1994 into the New Millennium)

615 Reengineering TMOD

616 Data Capture Process

618 Activity Plan Process

619 Reinventing the Future

621 “Bridging the Space Frontier”

624 TMOD Primary Challenge: 1997

627 Endnotes

629 List of Figures

641 Appendix

657 Index 

??? About the Author

??? Other Books in the NASA History Series

xii

Uplink-Downlink: A History of the Deep Space Netw
FOREWORD

From the very beginning of its association with NASA in 1958, the Jet Propul

Laboratory (JPL) received its fair share of public recognition for its successes and 

ures in pursuing the exploration of deep space. It started with the Explorers, the 

American satellites to orbit Earth. Later there came the Rangers, the first spacecraf

reach the surface of the Moon; the Mariner spacecraft, first to visit Venus and M

and the Voyagers that pushed the boundaries of deep space communication further 

to Jupiter and Saturn, and eventually to Uranus and Neptune. There were other sp

craft that put landers, probes, or orbiters into planetary orbits or atmospheres, or o

planetary surfaces. There were probes whose mission was to explore the composition 

dynamics of the interplanetary medium, and probes to observe the physics of the S

There were the huge missions, such as Viking to Mars, Galileo to Jupiter, and Cas

to Saturn, and there were small missions like Pathfinder to Mars and the New Millenn

missions to asteroids and comets. There was also science that did not require a sp

craft for its experiments such as radio astronomy, radar astronomy, and the search 

extraterrestrial intelligence.

The public accolades that were engendered by the bountiful science returned from 

of these NASA projects were shared by NASA and the scientists whose exquisite ins

ments and innovative interpretation of the data produced the new knowledge refle

in their results. However, what the press conferences, news releases, and media cove

did not reveal was the incredibly complex infrastructure that made each of these m

velous deep space missions possible. This infrastructure, which had been built over 

years at JPL, included the Deep Space Network (DSN), an essential, integral par

every mission. There was, in effect, a relationship between the planetary missions, 

spacecraft that carried them out, and the Deep Space Network that enabled such m

sions to be planned in the first place.

Without the remarkable improvement in performance of the DSN, scientific miss

to the distant planets would have been impossible. In 1964, when Mariner IV flew 

Mars and took a few photographs, the limitation of the communication link meant 

it took eight hours to return to Earth a single photograph from the Red Planet. 

1989, when Voyager observed Neptune, the DSN capability had increased so much 

almost real-time video could be received from the much more distant planet, Neptu

It is timely that, some 40 years after its inception, the Deep Space Network should 

recognized for its remarkable litany of progress in radio communications over vast 

tances, thereby allowing planetary scientists to collect data from sites throughout 
solar system. This book succeeds in bringing the history of the DSN forward for 

attention of curious, generally informed, or technical specialist readers.

NASA is to be commended for commissioning this book as part of its History Se

for the NASA/JPL Deep Space Network is the world’s largest and most advanced fa

ty for tracking, navigating, and acquiring data from interplanetary spacecraft. Worldw

in scope, and international in concept, the DSN has supported not only NASA sp

missions, but also those of the space agencies of Japan, Germany, Russia, France, 

Canada. Also, in concert with a NASA policy of international cooperation, the resou

of the Network have been made available to support qualified enterprises from all nati

In planning this book, New Zealand-born author Douglas Mudgway was faced with 

formidable problem of making an extremely complex technology comprehensible to 

curious or generally informed reader, while at the same time presenting for the spe

ist reader a historically accurate account of the advance of the technology that m

possible more sophisticated planetary missions. The task was further complicated by 

fact that the DSN was in a constant state of change, changes that were in consona

with the requirements of the space missions it was supporting.

For the former type of reader, Mudgway describes what the DSN actually did, wi

the framework of several overarching eras, each corresponding to a period of time d

ing which a major NASA deep space mission dominated the public scene. The Mari

Viking, Voyager, and Galileo Eras are examples. He provides an inside view of wha

took to design, build, and operate those tenuous radio communication links betw

the controllers, engineers, and scientists at computer terminals at JPL and billion 

lar spacecraft about to land on Mars, orbit around Jupiter, or fly through the ring

Saturn.

For the latter reader, the author provides an excellent review of the growth of the 

cialized technology that underlaid the remarkable expansion of Network capability 

enabled the design of increasingly ambitious planetary missions. A comprehensive app

dix provides help for the technical researcher. 

The unique capabilities of the great antennas of the DSN, together with a generous NA

policy of making them available for non-NASA scientific research, attracted radio 

radar astronomers from the United States and many other countries to the extent 

the requests for observing time far exceeded the time that could be made available 

these ground-based scientific purposes. Chapter 8, “The Deep Space Network as a Scien

xvi

Uplink-Downlink: A History of the Deep Space Netw
Instrument,” brings this important aspect of the work of the DSN to the attention 

the reader, and provides a basic review of the published work that resulted. 

Uplink-Downlink transforms the technical records of a major NASA facility, uniqu

the world, into a viable historical narrative covering 40 years of its critical involvem

in the United States space program. The Deep Space Network emerges from this st

not only as a complex, human-machine system of worldwide dimensions, but also, m

convincingly, as a focus for the aspirations of the NASA scientists for ever-bigger scie

and of the JPL engineers for ever-greater innovation and enterprise in navigating to 

tant targets and communicating at ever-greater data-rates, in spite of the fluctuation

available NASA funding for both, driven in some measure by the conflicting prior

of the piloted versus unpiloted programs within NASA itself.

Throughout the narrative we observe the interaction of these powerful currents, not f

the lofty heights of a dispassionate historical observer, but from the eye-level of a d

cated participant, for the author’s long career at JPL was played out at the vortex of t

often conflicting currents of self-interest. As a consequence, the engineers, technici

scientists, and managers at NASA, JPL, and its partner institutions in Spain and Austr

whose names appear from time to time in this book, are presented as real-life people c

tributing their various talents to the milieu in which they found themselves. It was 

totality of these individual efforts, driven by a common inquiring interest in space 

focused toward the common goal of its exploration, that produced the remarkable e

ty known throughout the world as the NASA Deep Space Network. 

I am confident that this work will be a valuable addition to the documented histor

the United States space program.

W. H. Pickering

Foreword
ACKNOWLEDGMENTS

To have been part of the history recorded here is sufficient reason in itself to ackno

edge my indebtedness to many colleagues in the DSN who supported and assisted 

throughout my long and rewarding career at the Jet Propulsion Laboratory (JPL). T

said, there remains the need to recognize the important contributions that were m

to the writing of this history by many of those engineers and scientists, and by o

persons less directly associated with my life in the Deep Space Network.

I must begin with Nicholas A. Renzetti, for it was he who brought me from Aust

to the United States in 1962 to begin a career at the Deep Space Instrumentation Fac

(DSIF), and it was he who, in 1996, after I had retired from JPL, stimulated my 

sonal interest in producing a history of the Deep Space Network. When the pro

began to falter for lack of funding support, MacGregor Reid provided much nee

encouragement, and Paul Westmoreland responded with the limited resources avail

to him to keep it going.

Later, when those resources expired, the project came to the attention of the NA

Chief Historian, Roger Launius. His encouragement, backed with adequate resour

moved the project rapidly forward to completion. Without his enthusiastic support 

unlikely this book would have been published. Along the way, I was ably assisted 

Louise Alstork and other members of the NASA History Office staff.

As the work got under way, my access to historical documents, files, and photogra

was eased immeasurably by the generous help of members of the JPL Archives 

Records section, notably John Bluth, Elizabeth Moorthy, and Robin Morris.

At all times, Shirley Wolff of the Telecommunications and Missions Operations (TM

Outreach Office was my lifeline to the daily pulse of the Network. I came to dep

on her patience and energy for transmitting documents and other technical material p

vided, at my request, by various engineers and scientists associated with the Netw

She, too, helped in bringing this project to life.

Last and longest, but by no means least, were the contributions in the form of in

views, discussions, technical briefings and materials, narrative reviews, and encouragem

on various DSN-related topics that were provided by: Catherine Thornton on geod

Michael Klein on the search for extraterrestrial intelligence; Martin Slade on radar astr

omy; James Hodder on network operations; Thomas Kuiper, Marvin Wick, and Pam

Wolken on radio astronomy; George Textor on Voyager; Leslie Deutsch on DSN tele
try for Galileo; Joseph Wackley for DSN systems; Joseph Statman on the Big Vit

Decoder; Robert Wallace on 34-m antennas; Dan Bathker on microwaves; Robert Cl

on masers; Charles Stelzried on system noise temperature, Venus Balloon, and Gio

Bob Preston and John Ovnick on orbiting VLBI; Fred McLaughlin on the 70-m an

nas; Dale Wells on 70-m antenna maintenance; James Layland on coding and array

Patrick Beyer on Galileo; Dennis Enari on Ulysses and Mars Pathfinder; Marvin Tra

on Mars Observer; Allen Berman on Magellan; Robert White on 34-m antennas; Tho

Wynne for photographs; Ronald Gillette on Cassini; John McKinney on Mars Missi

Ed Massey on Voyager and Ulysses; Nick Fanelli and Joe Goodwin on the Earth orb

and reimbursables; Bob Ryan and David Lozier (Ames Research Center) on the Pione

Michael Stewart on Magellan; Don Mischel, Tom Reid, Richard Mallis, and Robert

Stevens for early background material; George Schultz for an early draft; and fin

Olivia Tyler, Bobby Buckmaster, and Lynda McKinley for miscellaneous but never

less indispensable help.

The onerous task of reviewing the draft version of the book was undertaken by L

Dumas, Michael Hooks, Roger Launius, MacGregor Reid, Gael Squibb, and Jose Ur

Their insightful comments and suggestions greatly enhanced the accuracy, consiste

and quality of the narrative.

The families of Nicholas Renzetti and William Merrick kindly provided backgro

material on the personal lives of these two important figures in the history of the D

Space Network. Their contributions are gratefully acknowledged.

Douglas J. Mudgway

Sonoma, California

xx

Uplink-Downlink: A History of the Deep Space Netw
PREFACE

Although the subtitle for this book, “A History of the Deep Space Network” has an 

of finality about it, the suggestion of a task ended or a work completed, that does 

represent the true state of affairs. The Deep Space Network (DSN) is really a work 

progress. It had a beginning, of course, and a life that, at the time this book was w

ten, had spanned four decades. That is what this book is about. The task of record

“what happened next” will fall to future historians.

Eloquent histories of NASA’s planetary explorers have been written by others, and it 

not my intent to revisit those magnificent enterprises. To them belonged the high dr

associated with spacecraft encounters and landings on distant planets, spectacular laun

es, startling new science, and stunning color images from distant corners of the solar syst

As a key element in all of those dramatic spacecraft events, the DSN shared their exc

ment, but saw a quiet, unreported drama of its own. There were occasions when 

success or failure of a multimillion dollar spacecraft, the reputation of NASA, or 

recovery of critical science data from a far planet, lay in the hands of the DSN a

not infrequently, those of a crew member at a distant tracking station. Such events app

throughout the narrative. More often though, the determined, sometimes heroic, eff

of engineers and technicians in laboratories at JPL, and in control rooms and anten

at remote tracking stations, provided drama enough for those of us who were awar

it. Struggling to meet the seemingly insatiable demands of the planetary space miss

for more, bigger, or better capability, and all of it sooner, those individuals bore 

brunt of the burden of change that characterized progress in the DSN from its be

ning. These events, too, are identified in the narrative. 

In these pages, the informed reader will discover a simple description of what the D

is about, and how it works—an aspect of NASA’s spectacular planetary program 

seldom found its way into the popular media coverage of those major events. Fu

historical researchers will find a complete record of the origin and birth of the D

its subsequent development and expansion over the ensuing four decades, and a desc

tion of the way in which the DSN was used to fulfill the purpose for which it 

created. At the same time, the specialist reader is provided with an abundant sourc

technical references that address every aspect of the advanced telecommunications te

nology on which the success of the DSN depended. And finally, archivists, educat

outreach managers, and article writers will have ready recourse to the inner work

of the DSN and how they related to the more publicly visible events of the plane

space program. 
Despite the way it might have appeared to many of us within it, the DSN was not 

ated as “an end unto itself;” it was created by NASA to serve the needs of the NA

planetary spaceflight program. The spaceflight projects like Mariner, Surveyor, Pion

Viking, Ulysses, Galileo etc., were its “customers.” It seemed appropriate, therefore

record the history of the DSN against a timeline based on the great planetary exp

ers. Indeed it was their requirements for tracking and data acquisition services, to supp

more ambitious flight missions, that drove the DSN to the heights of excellence 

achievement described herein.

At some point in the future it will be timely to produce another history of the D

The present work will serve as a clear point of departure for what follows, for 

that time the rapidly diminishing “corporate” memory reflected herein will have s

ly been lost. There is a final point to be made. At a conservative estimate, NA

invested $4–5 billion over 40 years in developing and operating the Deep Sp

Network as a major NASA facility. An investment of public money of that ma

tude deserves a public record of how the money was spent and an account of 

return on the investment. Hopefully, this history will suffice for that purpose a

Those were my objectives in writing this book.

Before proceeding further, a few words about internal communications practices wi

the DSN organization at the Jet Propulsion Laboratory (JPL) during the period cov

in this history is in order. Perhaps in keeping with the very nature of JPL’s acade

associations, communications within the various departments, offices, laboratories, 

individuals that constituted the DSN at JPL were always very informal. Most inte

tions between engineers and managers and their people were conducted “eyeball to eyeb

in offices, corridors, bathrooms, or cafeterias, as the need arose. When two or more p

ple were together, a vacant office was used as an ad hoc conference room. Larger gro

met in a designated conference room, where the overhead projector and transparen

were the communications medium, and a handout, consisting of hard copies of 

transparencies, on which the attendee made notes, was the only record of the mat

presented and the decisions reached. Interoffice memos were generally used to add

issues that went beyond the writer’s immediate organizational boundary. Anyone co

write a memo on any subject, and did, when a meeting would not suffice. There n

was a centralized, or even unified, filing system within the DSN organization. Everyb

was responsible for keeping their own files in any way they chose. However, throu

out the laboratory, there was always a paper reduction or “records roundup” program 

effect. People were continually encouraged to discard inactive files in the interests of 

ing space. Furthermore, when people retired, they took files with them or discar

xxii

Uplink-Downlink: A History of the Deep Space Netw
them. So, for one reason or another, all DSN interoffice memos and personnel f

with few exceptions, have disappeared. 

Fortunately, however, this loose approach did not apply to documents that were ti

ly controlled by the formal DSN Documentation System. It was generally consid

that anything worth preserving should be published in a formal document, and 

sonnel were strongly encouraged to do so. As a result, a most complete record of D

activity in research, engineering, and deep space tracking “operations” is to be found 

the series of documents called “Progress Reports.” Such reports are referenced extensi

in the chapters that follow, and are readily available from the JPL Archives Section

The regrettable absence of interoffice memos, meeting minutes, verbatim records of 

cussions, letters, personnel records, etc., relating to DSN activity through the years accou

for the paucity of anecdotal material carried in the narrative. 

The NASA Deep Space Network is a crucial element in the mission to explore our s

system. Its main purpose is to provide a high-quality communications link between 

Earth-based mission control center and the many spacecraft of the United States 

several foreign countries that are, or were, engaged in that mission. Over the forty y

since the inception of the Deep Space Network, its people have been engaged in a c

tinuous, pervasive drive to refine communications links. The remarkable record 

achievement described herein is the result of their effort. 

In choosing Uplink-Downlink as the primary title of this book, I endeavor to conve

the reader the key characteristic of the Deep Space Network and the essential focu

the people who make it work.

This theme, Uplink-Downlink, runs through the book and is used to show how 

DSN has developed from a single-mission network of limited capability to a giant m

tiple-mission network. Together with a series of innovative improvements in spacec

communications systems, the Network provides a deep space communications capa

ty which now exceeds its modest beginnings by 12 orders of magnitude.

While the DSN is a prime example of exquisite telecommunications technology 

engineering, it is a fully operational, global system of people and machines suppor

NASA and other programs of planetary exploration. The way in which the DSN 

supported these programs through the years, and the part it has played in all of 

momentous and historical scientific discoveries resulting from this endeavor, forms 

timeline against which the history of the DSN is described.

x

Preface
The spectacular successes, and occasional failures, of NASA’s ventures into space are 

covered by the media in various forms. We are quite accustomed to live television 

erage of new spacecraft launches; scientists presenting their latest “amazing” facts 

pictures; images from remote spacecraft flying by, onorbit about or on the surfac

distant planets; and NASA animation movies of complex inflight or orbital maneuv

The complex infrastructure of tracking stations, intercontinental communication li

data processing services, and highly skilled engineers and technicians that make it 

possible are seldom mentioned, much less shown, on screen.

That infrastructure, so essential to the NASA program of Planetary Exploration, is kno

as the Deep Space Network. The fascinating history of its evolution, from a sim

ground-based antenna and receiver recording the signal from a telemetry transm

onboard the first simple spacecraft attempting to reach the Moon, to the present wo

wide network of giant antennas keeping track of spacecraft at the edge of the s

system, is the subject of this book.

Like the NASA space program itself, the history of the Deep Space Network is on

continual change, of performance enhancement, of striving for excellence and, of go

where none has gone before.

To provide the general reader with a basis for understanding the significance of th

changes in the context of the Deep Space Network, we begin with a simple discus

of the dynamics of spaceflight and why a tracking station is needed to maintain c

tact with an artificial object in space. The function of a deep space station in keep

track of one or more spacecraft is addressed, and is followed by an explanation of h

a tracking station does what it does. Then, since the course of history in the Deep Sp

Network was determined at various times by decisions based on radio frequency t

nology, it seemed that a short discourse on the principles involved would be in ord

The early phase of DSN history, from its inception in 1958 to the mid-1970s, was a

ciated with NASA’s first attempts to fly spacecraft to the Moon, Venus, Mars, and Jup

I have chosen to call this the Mariner Era because most of the major DSN deve

ment was driven by the requirements of the Mariner missions. By 1974, the Mar

Era was drawing to a close and the Viking Era of the bigger, more complex, more c

ly missions to revisit the planets, was beginning. The Viking Era opened in 1975 w

the Viking mission to Mars.

Dependent on the NASA planetary exploration program for its funding, the DSN c

tinued to evolve in size, capability and cost at a rate commensurate with the leve

xxiv

Uplink-Downlink: A History of the Deep Space Netw
NASA interest in unmanned exploration of the solar system. For the next twenty-

years, the Voyager, Galileo, and Cassini programs were the principal drivers for exp

sion and development in the Deep Space Network. Each program effectively determi

a unique era of influence in the overall story of the DSN. 

From the outset, the esoteric technologies of deep space telecommunications and in

mation processing were dominant features of research and development programs in 

DSN. Key characteristics of this work are described in chapter 7, “The Advance 

Technology in the Deep Space Network.”

Much of the technology in the Deep Space Network shares a lot in common with 

of the giant radio telescopes of the world. It should not be surprising that the an

nas of the Deep Space Network were used, both individually and in collaboration w

various radio astronomy observatories, for radio astronomy investigations as an adju

to their principal task of spacecraft tracking. These investigations, and others related 

scientific experiments that involved the DSN but did not involve a spacecraft, are descri

in chapter 8, “The Deep Space Network as a Scientific Instrument.” 

To organizations born of the space age, and particularly those involved directly with 

NASA space program, growth and change were almost synonymous. Through the y

covered here, organizational changes at NASA Headquarters, at Caltech’s Jet Propul

Laboratory (parent body of the DSN), and within its own management structure, w

a continual and essential part of its evolution. The changes that took place and t

impact on the DSN ability to cope with conflicting challenges for new planetary m

sions, while continuing support for ongoing missions within a fluctuating level of NA

funding support, is the substance of chapter 9, “The Deep Space Network as 

Organization in Change.”

I have elected to address the general reader in describing the history of the DSN, w

the expectation that a specialist reader will take advantage of the references I have g

to follow-up in specific areas of interest using the rich repository of related techn

material contained in the series of Tracking and Data Acquisition (TDA) Progress Rep

now available on the World Wide Web at http://tda.jpl.nasa.gov/progress_report.

Preface
INTRODUCTION

Surely there can be few people in this

day and age who are not familiar with

the television images of a NASA spacecraft blasting off from Cape Kennedy in

a splendid gout of smoke, fire, and steam

to a rendezvous with an asteroid, comet,

or planet in some remote corner of the

solar system. From the comfort of our

living rooms we watch the launch rocket rise majestically off the pad, pass

through the local cloud cover at the

launch site and soon become an everdiminishing point of light in the center

of the television screen. Sometimes we

observe the booster rockets burn out and

drop away before the main rocket stage

engines accelerate the vehicle and its delicate planetary payload out of sight. The

Titan-Centaur launch of Voyager 1,

shown in Figure Intro-1, was a typical

example. What happened next? you may

ask and, Where did that whole thing go?

Months or even years after a launch, an

item on the evening television news covering a NASA press release about an

impending rendezvous of a NASA

spacecraft with Mars, Jupiter, Saturn, or

an asteroid, followed by a video clip or

the latest set of pictures from the planetary object, might have caught the

attention of viewers. For certain, the pictures showed areas and details never

before seen and will be said to have risen

new questions about origins and development of the solar system, and possibilities for water, maybe even life, on the pl

or one of its satellites. The Voyager 1 view of Jupiter as the spacecraft approached 

x

Figure Intro-1. Voyager 1 outward bound 

Jupiter, September 1977. Voyager 1 was launc

by a Titan-Centaur vehicle from Cape Kenned

5 September 1979. After encountering Jupite

February 1979, Voyager 1 used a gravity-a

maneuver to reach Saturn in November 1980. It 

continued on a trajectory which eventually too

beyond the boundary of the solar system. Tw

years later it had become the remotest of all sp

craft and was still being tracked by the Deep Sp

Network in 1998.
xxviii

Uplink-Downlink: A History of the Deep Space Netw

planet, shown in Figure Intro-2, is a prime example of science data return with h

value for public interest.

There will be some with enquiring minds who may connect new scientific evidence w

a spacecraft launch, recalled from the distant past (see Figure Intro-1), and ask the q

tion, How did “it” get from there to what I am seeing now? (See Figure Intro-2.) 

Well, the answer depends on what is meant by “it,” but an essential part of the ans

is the subject of this book, namely, the Deep Space Network. To properly underst

that part of the answer, some explanation of the nature of the problem and the ter

nology used to describe it will be necessary. The discussion that follows is directed 

Figure Intro-2. Voyager 1 views Jupiter close up, February 1979. One of the most specta

lar planetary photographs ever taken, this close-up picture of Jupiter was taken by Voyager 1 

its approach to Jupiter in February 1979. Passing in front of the planet are two of the Galilea

satellites, Io and Europa. Both satellites are larger than Earth’s Moon, and the Great Red Spo

seen on Jupiter’s surface is larger than Earth itself. 
that end, to readers who have a general interest in the subject but whose field of p

fessional interest lies elsewhere. For the expert reader, numerous technical references 

provided throughout the book for followup on topics of specific interest.

Before beginning a discussion of radio communication with spacecraft traveling in d

space, we shall briefly review the environment of space and the motions of planetary sp

craft within that environment. This review and the discussion of space communicat

that follows it will explain various technical terms commonly used in describing the e

ronment of space, the motions of Earth and spacecraft, and space communications. 

hoped that the general reader, who may not be familiar with many of these terms, 

find this helpful in understanding the terminology used in the main chapters of the bo

The Solar System

NOTE: The following discussion makes extensive use of material contained in “The B

of Space Flight,” a learning document produced by the Jet Propulsion Laboratory for us

its spaceflight operations training program.

The solar system has been studied for religious or scientific reasons from the very 

liest times. For most of that time, studies of the solar system have had to rely on indi

measurements of the various objects in the solar system such as the visible light em

ted by, or reflected from the objects, or later, by the radio waves emitted by the S

However, with the emergence of space flight, instruments can be sent to many obj

in the solar system to make direct measurements of their physical properties and dyn

ics, at close range. Data collected from such measurements have resulted in 

unprecedented increase in our knowledge of the solar system.

Size and Composition

The solar system consists of an “average” star we call the Sun and the planets Merc

Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. It also includes num

ous satellites of the planets, comets, asteroids, meteoroids and of course, the interplane

medium. The planets, most of the satellites of the planets, and the asteroids, rev

around the Sun in the same direction, in nearly circular orbits. The Sun and the p

ets rotate on their individual axes. Except for Pluto, all the planets orbit the Sun in 

near the same plane, called the plane of the ecliptic.

The most common unit of measurement for distances within the solar system is 

astronomical unit (AU). One AU equals the mean distance of the Sun from Earth, ab

Introduction
150,000,000 km. Prompted by the need for a more accurate figure for spacecraft n

igation purposes, the DSN refined the value of the AU in the 1960s using radar ech

from Venus. Distances within the solar system, the distance between a DSN ante

on Earth and a planetary spacecraft for instance, are often indicated in terms of the 

tance light travels in a unit of time at the speed of 300,000 km per second.

For example:

Light Time Light Travels Approx. Distance

1 second 300,000 km 0.75 Earth-Moon

1 minute 18,000,000 km 0.125 AU

8.3 minutes 150,000,000 km 1 AU, Earth-Sun

1 hour 1,000,000,000 km 1.5x Sun-Jupiter

Although the Sun is characterized as a typical star, it dominates the gravitational f

of the solar system; it contains 99.85 percent of the mass of the solar system. All 

planets combined contain only 0.135 percent of the total mass with the satellites of 

planets, asteroids, meteoroids and interplanetary medium making up the balance of 0.

percent. Even though the planets account for only a small portion of the total mas

the solar system, they retain the greater part of the angular momentum of the solar 

tem. This storehouse of energy can be utilized by interplanetary spacecraft to m

so-called “gravity assist” changes in their interplanetary trajectories.

In terms of volume, nearly all of the solar system appears to be an empty void. Far f

being just nothingness, however, this void comprises the interplanetary medium 

includes various forms of energy and at least two material components: interplane

dust and interplanetary gas. The dust consists of microscopic particles which can 

measured by special instruments carried by interplanetary spacecraft. Interplanetary 

is a tenuous flow of gas and charged particles called plasma, which when streaming f

the Sun is called solar wind. The solar wind can also be measured by interplane

spacecraft. The point at which the solar wind meets the interstellar medium, that is 

stellar wind streaming from other stars, is called the heliopause. This boundary, wh

marks the edge of the Sun’s influence, is theorized to lie perhaps 100 AU from the S

At the time of this writing, the Voyager and Pioneer spacecraft were making their 

toward this remote limit of the solar system. The magnetic field of the Sun extends 

ward into interplanetary space and it, too, can be measured by instruments carried 

planetary spacecraft.

xxx

Uplink-Downlink: A History of the Deep Space Netw
The Terrestrial Planets

The four terrestrial planets of the solar system—Mercury, Venus, Earth, and Mar

have a firm rocky surface similar to that of Earth. The orbits and mean distances of 

terrestrial planets from the Sun are shown in Figure Intro-3. 

None of the terrestrial planets has rings. Earth has a layer of rapidly moving charged p

cles known as the Van Allen Belt, first detected by the JPL Explorer 1 space probe in 19

The Jovian Planets

The four Jovian planets—Jupiter, Saturn, Uranus, and Neptune—are all much la

than the terrestrial planets and have gaseous natures like that of Jupiter. They all h

satellites and rings, although the size and number of each varies considerably betw

them. The orbits and mean distances of the Jovian planets from the Sun are shown 

Figure Intro-4. 

Introduction

Figure Intro-3. Mean distances of the terrestrial planets from the Sun. The orbits in this 

ure are drawn approximately to scale. The orbit of Jupiter is shown for scale reference only.

Terrestrial Planetary Data (Approximate)

Mercury Venus Earth Mars

Mean

distance

from Sun 0.39 AU 0.72 AU 1.0 AU 1. 5 AU

Light

minutes

from Sun 3.2 5.9 8.3 12.5

Mass

in terms

of Earth’s 0.05 0.89 1.00 0.11

Radius

in terms

of Earth’s 0.38 0.95 1.00 0.53

Rotation

rate

Earth days 59 243 1.00 1.03

(retrograde)

Satellites 0 0 1 2

MERCURY

VENUS

SUN

EARTH

MARS

JUPITER

(Shown for Sc

MOTION

Viewed

from

North

LIGHT MINUTES ASTRONOMICAL UNITS

43 13 8.3 3.2 0 .39 1.0 1.5 5.2
xxxii

Uplink-Downlink: A History of the Deep Space Netw

Inner and Outer Planets

Frequently, the planets whose orbits lie inside Earth’s orbit—namely, Venus 

Mercury—are referred to as the inner planets. Mars, Jupiter, Saturn, Uranus, Neptu

and Pluto are generally known as the outer planets.

Asteroids 

Asteroids are rocky objects orbiting the Sun at a distance of about 2.7 AU, between 

orbits of Mars and Jupiter, and moving in the same direction as the planets. They v

from the size of pebbles to objects measured in hundreds of kilometers. Some have or

which cross the orbit of Earth from time to time. The DSN Solar System Rada

Goldstone is used to investigate the properties of asteroids with Earth crossing orb

Comets

Comets are believed to be composed of rocky material and water ice. Their highly e

tical orbits bring them very close to the Sun and swing them deeply into space o

Figure Intro-4. Mean distances of the Jovian planets from the Sun. The orbits in this fi

are drawn approximately to scale. Pluto, at a mean distance of 39.5 AU from the Sun, is not 

cussed in this book and is omitted from the figure to accommodate the scale of the other plan

Jovian Planetary Data (Approximate)

Jupiter Saturn Uranus Neptune

Mean

distance

from Sun 5.2 AU 9.5 AU 19.2 AU 30.1 AU

Light

hours

from Sun 0.72 1.3 2.7 4.2

Mass

in terms

of Earth’s 318 95 15 17

Radius

in terms

of Earth’s 11 9 4 4

Rotation

rate

in hours 9 10.5 15.6 18.4

Number

of known

satellites

(1993) 16 14 15 7

JUPITER

SUN

SATURN

MARS

(Shown for Scale)

NEPTUNE

LIGHT HOURS ASTRONOMICAL UNITS

4.2 2.7 1.3 7.2 0 1.5 5.2 9.5 19.2 30.1

URANUS
beyond the orbit of Pluto. Comet structures are diverse and very dynamic, but they 

develop a cloud of diffuse material called a coma, that usually grows in size and bri

ness as the comet approaches the Sun. A small bright nucleus is usually visible in 

middle of the coma. The coma and nucleus together constitute the head of the com

As a comet approaches the sun it develops an enormous tail of luminous dust ma

al that extends for millions of kilometers from the head away from the sun. It 

develops a tail of charged particles and an envelope of hydrogen. Several comets h

been investigated by planetary spacecraft flying close to or through the coma.

Earth and Its Reference Systems

Without a system of coordinates to consistently identify the positions of observers, p

ets, and interplanetary spacecraft, exploration of the solar system would not be possi

Because space is observed from an Earth platform, a system of Earth coordinate

required to establish the position of the observer. The locations of DSN antennas 

Earth’s surface are specified in terms of latitude and longitude.

To establish a coordinate system for the sky, the concept of a celestial sphere whose ce

is at the center of the Earth, is used. The celestial sphere has an imaginary radius la

than the distance to the farthest observable object in the sky, that is to say, it extends 

beyond the limits of the solar system. The extended axis of Earth intersects the north 

south poles of the celestial sphere. The direction of a spacecraft, planet, or star, or any o

celestial object, can be specified in two dimensions on the inside of this sphere using a 

tem of coordinates analogous to Earth’s latitude and longitude system. Although the refere

origins are different, the analogous terms latitude and longitude on the celestial sphere 

declination (DEC, latitude) and right ascension (RA, longitude). When used in connec

with a specific location such as a DSN antenna, at a particular time of day, the term 

is replaced by a different term called hour angle or HA. 

A somewhat simpler system for describing the position of a distant spacecraft relativ

a particular antenna and time of day uses the local horizon and true north as its re

ences. Its measurements are azimuth (AZ), measured in degrees clockwise around the hor

from true north and elevation (EL), measured in degrees above the local horizontal dat

Optical telescopes, radio telescopes, and the DSN antennas are designed with mount

that make best advantage of either the HA-Dec or Az-El coordinate systems.

In a HA-Dec system the HA axis is parallel to Earth’s axis of rotation. Thus an an

na built on a HA-Dec mount has the advantage that motion is required mostly in o

one axis, HA, to track an object like a spacecraft, as Earth rotates. The disadvantag

xx

Introduction
xxxiv

Uplink-Downlink: A History of the Deep Space Netw

that it requires an asymmetrical design, which is unsuited to the support of very he

structures. By contrast, Az-El mounted antennas are basically symmetrical structures wh

can support heavy weights, but to track celestial objects they require driving in two a

AZ and EL simultaneously. However, the advent of high speed computers has obvi

the problems formerly associated with converting coordinates from one system to 

other. The essential differences between the HA-Dec and Az-El types of mount for D

antennas are illustrated in Figure Intro-5.

Earth Motions

Earth rotates on an axis inclined at 23.5 degrees to the plane of its orbit around the S

Its period of rotation is 24.0 hours mean solar time. This motion is of prime importa

to the configuration of the Deep Space Network. Due to the rotation of Earth, a sp

craft moving away from Earth along its trajectory in space appears to an observer 

Earth to set toward the west. To an observer further west, the spacecraft will appea

rise in the east and travel across the sky until, 8 to 10 hours later, it sets. The pro

repeats until 24 hours later the spacecraft appears, rising in the East for the first obs

er. It follows that three observers, each located 120 degrees of longitude apart on 

surface of Earth, would have the spacecraft continuously in view as the view period pa

from one to the other. This is the basic idea underlying the location of the three D

Space Communication Complexes of the Network at Goldstone, California, near Mad

Spain, and near Canberra, Australia. From these locations, approximately 120 degree

longitude apart, their great antennas, some HA-Dec, others Az-El, are able to main

continuous radio view of planetary spacecraft as Earth performs its daily rotations. 

Figure Intro-5. HA-Dec and Az-El mounted antennas of the DSN.

HA-Dec MOUNT

TYPICAL OF DSS-12, DSS

61, AND DSS-42

Az-El MOUNT

TYPICAL OF MORE RECENT

DESIGNS

HOUR-ANGLE

BEARING

ELEVATION

BEARING

AZIMUTH

BEARING

HOUR-ANGLE

COUNTERWEIGHT

HOUR-ANGLE AXIS

SUPPORTED SO AS

TO ALIGN WITH 

EARTH’S AXIS

(DECLINATION

COUNTERWEIGHT

STRUCTURE OMITTED

FOR CLARITY)

(ELEVATION

COUNTERWEIGHT

STRUCTURE OMITTED

FOR CLARITY)

DECLINATION

BEARINGS
The ability of the DSN antennas to view the planetary spacecraft is not changed by 

annual rotation of Earth around the Sun. It does, however, introduce a cyclic chang

the distance between Earth and spacecraft depending on the orientation of the sp

craft trajectory relative to Earth’s orbit.

Time Conventions

In addition to local time and Greenwich Mean Time, there are several other systems 

measurement of time that are used for tracking planetary spacecraft in the Deep Sp

Network. Three of the most important are Universal Time Coordinated (UTC), E

Received Time (ERT), and Round-Trip Light Time (RTLT).

UTC is a worldwide scientific standard of timekeeping based upon carefully maintai

atomic clocks that are accurate to a few microseconds via the addition or subtraction 

leap seconds as necessary at two opportunities every year. Its reference point lies on 

Earth prime meridian at Greenwich, England. All spacecraft operations in the DSN 

conducted on the basis of UTC.

The time (in UTC) at which a DSN tracking station observes an event associated w

a planetary spacecraft is called the Earth Received Time (ERT). The time (in UTC) 

a tracking station observed the loss of signal due to a spacecraft occultation by a p

et would be an example of such an event.

The elapsed time that it takes a radio signal (traveling at the speed of light) to tr

from a DSN station to a spacecraft or planetary body, and after retransmission by 

spacecraft or reflection from the body, return to the tracking station, is known as 

Round-Trip Light Time (RTLT). It is used by the DSN to measure spacecraft range 

other navigational and scientific parameters. The RTLT from Earth to the Moon is ab

3 seconds; to the Sun, about 17 minutes. In 1993, the RTLT for the Voyager 1 sp

craft was 14 hours, 13 minutes. By the end of 1998, this had increased to 20 ho

18 minutes, making Voyager 1 the most distant spacecraft in the solar system. 

Interplanetary Trajectories

A spacecraft sitting atop a launch vehicle at Cape Canaveral can, in one sense, be c

sidered as already in orbit around the Sun by virtue of the motion of the Earth o

around the Sun. To send such a spacecraft to an outer planet, Mars for example, 

spacecraft’s existing orbit must be adjusted to cause it to intercept the orbit of Mar

x

Introduction
a single point. The portion of the new orbit between Earth and Mars is called the in

planetary trajectory.

To achieve such a trajectory, the spacecraft is lifted off the pad by the launch vehicle, 

above Earth’s atmosphere, orients itself to the right attitude and is accelerated in the di

tion of Earth’s orbit around the Sun to the extent that it becomes free of Earth’s gravitati

effect. The magnitude and direction of the accelerating force is carefully calculated 

achieve a new orbit which will have an aphelion (farthest distance) equal to that of 

orbit of Mars. After injection into its new orbit, the spacecraft simply “coasts” the res

the way to its destination. Of course, to get to Mars itself, rather than just to Mars’ o

the spacecraft must be inserted into its interplanetary trajectory at precisely the right t

to reach the orbit of Mars at the same time that the planet itself reaches the point w

the spacecraft will intercept the orbit of Mars. This calls for very precise timing ind

and results in constrained opportunities for launch called “launch windows.” A spacec

interplanetary trajectory can be adjusted or trimmed, to a limited degree, by mean

midcourse maneuvers which use the onboard thrusters to change the spacecraft speed 

direction, or by means of a “gravity assist,” which uses the gravitational force of a nea

planet for the same purpose. The motions of Earth that play an important part in 

interplanetary orbit insertion process are shown in Figure Intro-6.

xxxvi

Uplink-Downlink: A History of the Deep Space Netw

Figure Intro-6. Insertion into interplanetary orbit. For interplanetary launches, the spacecraft t

advantage of Earth’s orbital motion to supplement the limited energy available from the launch v

cle itself. In the diagram, the launch vehicle is in addition to using Earth’s rotational speed, accelera

generally in the direction of Earth’s orbital motion, which has an average velocity of approxim

100,000 km per hour along its orbital path. The launch vehicle is used to increase or decr

this velocity in the tangential direction to insert the spacecraft into the desired transfer orbit.

EARTH

ROTATIONAL MOTION

ORBITAL

 MOTION

TO SUN

LAUNCH USING EARTH’S ROTATIONAL AND ORBITAL VELOCITIES
The vital DSN operation of “initial acquisition” is performed during, or as close as p

sible to, the interplanetary trajectory injection maneuver right after launch. After t

spacecraft and mission controllers are entirely dependent upon the DSN for comm

cations with the spacecraft throughout the life of the mission.

The foregoing paragraphs have provided a greatly simplified answer to the question 

what happens to a spacecraft after it leaves the launch pad. They have also descri

the environment in which it will move for the rest of its life. An answer to the n

question, How do spacecraft and mission controllers communicate with their spacec

during its long passage through the environment of deep space? requires some un

standing of the nature of deep space communications. 

Deep Space Communications

The Deep Space Network makes use of electromagnetic radiation for communica

with interplanetary spacecraft. All planetary spacecraft are equipped with radio tr

mitters and receivers for sending signals to and receiving signals from the Earth-b

antennas of the DSN. In addition to signals from spacecraft, DSN antennas and recei

are capable of detecting signals from natural emitters of electromagnetic radiation, s

as the stars, the Sun, molecular clouds, and giant gas planets such as Jupiter. The “

nals” from these sources appear as random noise to the sensitive receivers of the D

and their study and interpretation is the field of radio astronomy. The DSN supp

many research projects in radio astronomy.

Bands and Frequencies

Electromagnetic radiation from the natural emitters combines with radiation from 

ficial sources to create a background level of electromagnetic noise from which the spacec

signals must be detected. The ratio of the signal level to the noise level is known as 

signal-to-noise ratio (SNR). SNR is one of most common terms used in the DSN 

describe the quality of a communication link.

Electromagnetic radiation with frequencies between about 10 kHz and 100 GHz 

referred to as radio frequency (RF) radiation. For convenience in managing its use, 

radiation is divided into groups called bands, such as S-band and X-band. The ba

are further divided into small ranges of frequencies, or channels, some of which are a

cated by international agreement, for the use of deep space telecommunications. 

following table shows the approximate range of frequency and wavelength for each ba

xx

Introduction
Radio Communication Bands vs. Wavelength and Frequency

Band Name Wavelength (cm) Frequency (GHz)

L 30–15 1–2

S 15–7.5 2–4

C 7.5–3.75 4–8

X 3.75–2.4 8–12

K 2.4–0.75 12–40

Early spacecraft used L-band for deep space communications. Within a few years

band replaced L-band, and more recently X-band came into general use for deep sp

communications. Experiments to demonstrate the advantages of telecommunications 

tems using K-band were in progress at the time of this writing (1997). Generally speak

the higher frequency bands offer greater advantages for space communications, altho

these tend to be offset by other factors, such as increasing losses at the highest ban

Doppler Effect

The Doppler effect is routinely observed as changes in the frequency of spacecraft ra

signals received by a DSN tracking station. This is caused by the relative motion betw

a spacecraft and the tracking station due to the spacecraft trajectory, its orbit aroun

planet, Earth’s orbit around the Sun, or the daily rotation of Earth about its axis. W

the distance decreases, the frequency decreases proportionally to the rate of chang

distance, and vice versa. If two widely-separated tracking stations observe a single sp

craft, they will have slightly different Doppler signatures. This information, describe

the Doppler type of radio metric data, is generated at the DSN tracking stations 

used by spacecraft navigators to describe the path of the spacecraft through deep sp

very precisely and in three dimensions. 

Cassegrain Focus Antennas

Whether the mount is of the HA-Dec or Az-El type, all DSN antennas, irrespectiv

their size, use the Cassegrain focus system to concentrate the electromagnetic energy i

dent upon their surfaces. The incident energy may originate from a distant spacecra

celestial body, or the station’s own uplink transmitter. It works equally well for either up

or downlink. A diagram of a cassegrain focus antenna is shown in Figure Intro-7.

In a Cassegrain antenna, a secondary reflector is added to the structure to fold the e

tromagnetic beam back to a prime focus near the primary reflector in the manner sho

xxxviii

Uplink-Downlink: A History of the Deep Space Netw
in the figure. Incoming electromagnetic waves are focused by the prime reflector on to 

secondary reflector, or hyperboloid, which refocuses them into the receiver feed horn lo

ed at the prime focus. Usually, several feed horns are mounted on a single cone struct

and by rotating the slightly offset secondary reflector, the main beam can be directed 

any receiver horn as required. For transmitting, the system works in the reverse way. 

This design accommodates very large-diameter antennas and allows bulky, heavy rec

ing and transmitting equipment to be located near the center of gravity of the compo

structure.

Uplink and Downlink

The radio signal transmitted from a DSN antenna to a distant spacecraft is known 

an uplink. The radio signal transmitted by the spacecraft to the DSN is known 

downlink. Uplinks or downlinks may consist of a pure RF tone called a carrier, o

carrier which has been modulated to carry information in each direction, including c

mands to the spacecraft or telemetry data from the spacecraft. A spacecraft communicat

link that involves only a downlink is called a one-way link. When an uplink is b

received by a spacecraft at the same time that a downlink is being received, the c

x

Introduction

Figure Intro-7. Cassegrain focus antenna.

Secondary

Reflecting Surface

(Hyperbolic Section)

CASSEGRAIN FOCUS ANTENNA

Incoming

Electromagnetic

Waves

Primary Reflecting Surface

(Parabolic Section)

Cassegrain

Focus Receiver

feed horn
munications mode is said to be two-way. These two distinct modes of operation pl

significant part in the operation of deep space communications. 

Signal Power

Typically, a local broadcasting station with a transmitting power of 50,000 watts will d

er an acceptable radio signal to a portable receiver at a distance of 100 km. How t

can a spacecraft transmitter, limited to a power of 20 watts, deliver an acceptable si

to a DSN receiver across hundreds of millions of kilometers of interplanetary space? 

first step involves concentrating all of the available energy into an extremely narrow b

pointed in one direction, rather than spreading it in all directions, as in a broadcast 

tion. At the spacecraft, this is done with a small parabolic dish antenna, typically on

five meters in diameter. Even so, when these concentrated signals reach Earth they h

vanishingly small power, perhaps as small as 1 x 10-20 watts. The rest of the solutio

provided by the receiving power of the large aperture antennas of the DSN and the extr

dinary sensitivity of its cryogenically-cooled low-noise receivers. Aided by special cod

and decoding schemes to discriminate against radio noise, the DSN can extract the 

ence and engineering data from these unimaginably weak signals and deliver it in real t

to the intended users. As this history will show, the ability of the DSN to do this 

improved by many orders of magnitude over the forty or so years since its inception

Coherence

In addition to its use as a conveyor of modulated telemetry data, the downlink carrier is 

used by the DSN for tracking the spacecraft and for carrying out some types of radio 

ence experiments. Each of these applications requires the detection of minute changes (fract

of 1 Hz) in many GHz of carrier frequency over many hours. This can only be acc

plished when the frequency of the downlink carrier itself is extremely stable and is kn

with very great precision. Since the spacecraft itself could not carry the massive equipm

needed to do this, it makes use of the uplink, which does have the requisite stability, 

frequency reference for the downlink. In effect, the spacecraft simply retransmits the D

uplink after modulating part of it with the desired telemetry data. When this is done, 

downlink is said to be two-way and coherent, that is, in-phase with the uplink. 

At each Deep Space Complex, a hydrogen maser-based frequency standard provides 

reference for generating an extremely stable uplink frequency for transmitting to the sp

craft. The resulting spacecraft downlink, based on and coherent with the uplink, has practic

the same high frequency stability as the original reference frequency standard. Compar

of one with the other at the phase level of individual cycles produces the desired track

xl

Uplink-Downlink: A History of the Deep Space Netw
or scientific data. The entire process ultimately depends for its success on the “phase co

ence” of the uplink and downlink carriers, and the accuracy with which corrections 

be made for the many sources of error in the end-to-end system. 

Under some operational conditions the spacecraft may not have an uplink. To cover s

cases, all spacecraft carry a small auxiliary oscillator, which serves as a reference for g

erating a non-coherent downlink in the absence of a DSN-generated uplink. It is 

highly stable and its frequency is affected by temperature variations on the spacec

Nevertheless, there have been numerous instances in the long history of the DSN w

a spacecraft’s local oscillator played a major role in saving an otherwise doomed sp

craft. Some spacecraft also carry a thermally stabilized ultra-stable oscillator (USO) wh

is used for precision radio science experiments involving planetary occultations. Bec

of stringent frequency requirements for spacecraft tracking navigation and radio scie

the DSN remains at the forefront of the technology for frequency and timing standa

Decibels

Perhaps the most commonly used technical term in the DSN is the ubiquitous deci

Since the term decibel (or dB) appears frequently in the following history, a simplif

non-rigorous explanation is in order. The decibel is a unit of measure used to desc

the ratio between two power levels. For example, the power delivered by a 100-w

audio amplifier is said to be 10 dB higher than the power delivered by a small 10-w

amplifier. The ratio of the powers is 10 to 1. Inversely, where the ratio is 1 to 10 (1/

the equivalent term would be -10 dB.

Because of its mathematical origin, the decibel scale is not linear, it is logarithmic; 

10 dB corresponds to a ratio of 10, 20 dB corresponds to a ratio of 100, 30 dB 

ratio of 1000 and so on. For ratios less than 10, 3 dB corresponds to a 2 to 1 po

ratio, 6 dB to a ratio of 4, etc. When the ratios are inverted they are represented b

negative sign before the corresponding dB value, so that a ratio of 1 to 2 or 1/2 is 

resented by -3 dB.

Much of the technical progress in the DSN is reflected in terms of dB values for h

power transmitters, gain of large antennas, threshold of receiving systems, gain of m

amplifiers, signal-to-noise ratios, bit-error rates for decoding systems, etc. 

The remarkable improvement in downlink performance that took place during the Mari

Viking, and Voyager Eras, the first three great eras of DSN growth, is shown gra

cally in Figure Intro-8. 

Introduction
In the context of this figure, improved downlink performance implies an increa

capability for a DSN tracking station to return more data at the same range, 

same data at a greater range, or some other enhanced combination of data and ra

from a planetary spacecraft. The effect of changes in operating frequency, from 

band to S-band to X-band, is evident in the stepwise improvements, as is 

contribution of the larger diameter antennas both individually and in array w

xlii

Uplink-Downlink: A History of the Deep Space Netw

Figure Intro-8. Improvement in DSN downlink performance during the first twenty year

this graphic, published by C. T. Stelzried et al. in 1982, downlink performance is stated in te

of the parameter M which relates the two key elements of downlink performance: the gain (

of the receiving antenna GR, and the noise temperature (sensitivity) of the receiving system, To

is expressed in dB as described above.

LEGEND:

• FREQUENCY IN GHz (8.4)

• ANTENNA DIAMETER

IN METERS (64)

• SYSTEM NOISE

TEMPERATURE

IN KELVINS (30)

VOYAGER 2

THRESHOLD

AT SATURN FOR

44.8 KB/S DATA RATE

8.4, 64 AND

34 ARRAY

8.4, 64 

25

8.4, 64, 30

2.3, 64, 25

2.3, 64, 50

2.3, 26, 50

0.96, 26, 60

NETWORK DOWNLINK PERFORMANCE (M = GR/Top), DB

0.96, 26, 220

0.96, 26, 1500

MARINER 4

(MARS)

MARINER 9

(MARS)

VIKING

(MARS)

VOYAGER 2

(SATURN)

1960 1970 1980 19

CALENDAR YEAR

70

60

50

40

30

20

10
other antennas. The parameter called system noise temperature is a measure of 

sensitivity of the maser receiving systems that are a key element in the overall 

formance of the downlink.

After the early 1980s, improvements in terms of dB were less dramatic, not becaus

any less incentive for further improvement, but because by that time the technolog

deep space communications was approaching the practical limits of physical realiza

for that era. More esoteric approaches, such as advanced data coding methods, w

called upon, and although significant improvements continued to be made, they w

much smaller in terms of dB. This issue, and how the DSN dealt with it, is discu

in chapter 7, “The Advance of Technology in the Deep Space Network.”

Modulation and Demodulation

Scientific and engineering data is generated by a planetary spacecraft in digital form 

modulated to an S-band or X-band carrier signal for transmission to the antenna

the DSN. Modulation is a two step process in which the bits of raw data are first app

to a subcarrier of much lower frequency. The data-modulated subcarrier is then app

to the RF carrier for radiation, via the spacecraft’s transmitter and antenna, to Ea

At the DSN receiving station, the process is reversed. Sensitive receivers detect the 

rier signal, extract the subcarrier and pass it to a subcarrier demodulator. The subcar

demodulator extracts the data and conditions it for recording and forwarding to J

Most spacecraft apply a complex code to the raw data to protect it against noise-indu

errors during transmission. Special equipment at the tracking stations performs the e

step of decoding the data before it is processed for recording and delivery. This end

end function of a deep space communication system, and the data associated with i

called telemetry.

There is an analogous function that uses the S-band or X-band uplink for transmis

of command data to a spacecraft. It is called command. In this case, the subcarrier m

ulated with a bit-stream of command data. At the spacecraft, the carrier is detected, 

subcarrier is demodulated and the command data bits are eventually passed to the c

mand system for immediate execution or for storage for later action.

The distance from Earth, or range, of a distant spacecraft can be measured by mo

lating the uplink with a special code or sequence of digital characters, which, w

turned around by the spacecraft and remodulated on the downlink, allow the time d

between transmission and reception to be determined with great precision. 

Introduction
Earth/spacecraft range is then calculated from knowledge of the time delay and the pr

agation velocity of the modulated radio signal. 

Spacecraft Radio System 

Intentionally, the spacecraft itself was not among the topics discussed up to this po

While a planetary spacecraft is a miracle of modern technology, the history of plane

spacecraft development is beyond the scope of this book. It is important to note, h

ever, that the spacecraft radio system is an integral part of a deep space communicat

system although not an integral part of the DSN organization during the period of t

covered here. The spacecraft radio system was provided by the flight project organ

tion as part of the spacecraft. Nevertheless, responsibility for RF compatibility betw

the spacecraft and the DSN was always a DSN responsibility. In the ensuing chap

where a spacecraft radio system is discussed, the general explanations given above 

suffice for an understanding of the matter.

An Essential Part of the Answer

In the preceding discussion, I elected to use generalities in describing some of the b

concepts of deep space communications. The reader will encounter all of these te

and topics many times as the history of the Deep Space Network unfolds. These c

cepts also allow us to answer the questions prompted by the launch pictures, and 

the remarkable new images shown at the press conference. An essential part of the ans

is provided by NASA’s Deep Space Network. Worldwide in concept, continuous in o

ation, the DSN is the link between the two images. The global scale of the Networ

illustrated by the map shown in Figure Intro-9.

In terms of the foregoing discussion, the Deep Space Network may be characterize

a scientific instrument of worldwide proportions that uses a single up- and down

radio signal, in combination with a coherent spacecraft transponder, to perform th

basic functions. Interplanetary spacecraft depend on the first two for their commun

tions with Earth. The third and no less significant function brings the DSN into 

science community in a more direct way. Each of these functions is associated with 

of the unique types of data carried on the up- and downlinks.

The first, and perhaps the most important, function is that of generating radio me

data. Consisting of Doppler data, ranging data, and interferometric comparisons betw

two tracking stations, radio metric data are used by spacecraft navigators to determ

the precise location of a spacecraft along its trajectory at all times. Radio metric 

xliv

Uplink-Downlink: A History of the Deep Space Netw
Introduction

Figure Intro-9. An essential part of the answer; global map of the Deep Space Network, 1992. The three DeepSpace Communication Complexes are located at intervals of 120 degrees of longitude around Earth, and are identifiedby the local name of the area and the generic name of the Complex

The antennas at each Complex are shown as they
are also key to the task of pointing the DSN antennas in the right direction to es

lish, and continuously maintain, a radio link between spacecraft and Earth. 

The second function, telecommunications, makes use of appropriate modulation impre

on the uplink (by a tracking station), and on the downlink (by a spacecraft), to c

nect a spacecraft with its Earth-based controllers. Command instructions are sent to 

spacecraft on the uplink, while engineering and science data are telemetered back 

Earth, on the downlink.

A third function relates to the use of the DSN as a scientific instrument for resea

in radio and radar astronomy. Scientists were quick to recognize the potential of 

state-of-the-art capabilities of the DSN as a powerful new resource for advancing t

experiments. Encouraged by a generous NASA policy for making time observa

available, the large antennas that could be pointed with great precision, sensitive receiv

and extremely stable timing systems of the DSN soon attracted the attention of m

of the world’s leading researchers. Using spacecraft radio signals, Extra-Galactic Ra

Sources or echoes from powerful radar transmitters at Goldstone, scientists conti

to use the DSN as a scientific instrument to widen our knowledge of distant reg

of the universe.

What follows is an end-to-end scenario that brings all the pieces together to desc

the deep space communications process for a typical planetary mission. 

Soon after the launch vehicle was lost to view on the television screen, the first s

booster burned out and fell away, leaving the injection vehicle, with the spacecraft attach

to coast for a short time until it reached the exact position and time for the trajec

injection maneuver to begin. At about that same time, the injection vehicle had mo

far enough around Earth to be in radio view for the DSN tracking stations in Austr

The Canberra stations tuned their receivers to the spacecraft’s auxiliary oscillator 

quency, making allowance for the one-way Doppler effect, and locked-on their recei

to automatically follow the spacecraft. The telemetry data on the one-way downlink 

ried engineering data that confirmed that the spacecraft survived the stresses of the lau

events. At the appointed time, the injection vehicle engine was fired to accelerate 

spacecraft free of Earth gravity and on to its interplanetary trajectory. The small in

acquisition antenna at Canberra had been following the spacecraft and now steered 

more powerful, but less agile, 34-meter antenna to point at the spacecraft where it 

locked up its receivers.

xlvi

Uplink-Downlink: A History of the Deep Space Netw
Telemetry data, demodulated and decoded at the tracking station, continued to f

to mission controllers at JPL, but they needed to send commands to the spacec

immediately to orient it to the Sun and to reconfigure it for its long cruise to 

planet. Besides, spacecraft navigators were anxious to have the better, more-st

Doppler data that was associated with the two-way, coherent mode. The transmi

at the tracking station was turned on, and making allowance for the uplink Dop

offset, its ultra-stable S-band (or X-band) uplink was tuned across the frequency 

the spacecraft receiver. On detecting the uplink, the spacecraft automatically switc

over to the coherent mode of operation and began retransmitting the uplink back 

the tracking station. The DSN receivers were then in the two-way, coherent mo

the two-way Doppler was reaching the navigators, and commands could be tr

mitted at any time as required. 

As the spacecraft continued to move away from Earth on its new trajectory, Earth r

tion brought the other DSN Complexes into view, and the stations there passed 

spacecraft in turn, from one to the other. This involved a complicated operational p

cedure to avoid losing telemetry data, but the net result was that communication w

the spacecraft continued, uninterrupted by Earth’s rotation, for the approximately 

remaining years of the mission.

During the long cruise period, the Navigation Team used two-way Doppler and ra

ing data generated at the tracking stations to verify, and when necessary adjust, 

trajectory of the spacecraft to ensure that it reached the planet at the correct posi

and time for a successful encounter. Because the distance between the spacecraft 

Earth had been steadily increasing, the power level of the carrier signal received by 

34-meter antennas gradually dropped to the point where the signal-to-noise ratio 

too low for the DSN receivers to operate properly. At that point, the tracking stat

changed over to the big 70-m antennas for tracking this spacecraft. The 70-m anten

allowed them to receive telemetry data at a higher data rate, a capability that would 

needed at the greater range of the forthcoming planetary encounter.

Encounter day finally arrived. All of the complex sequences of operation that the sp

craft would carry out during encounter had been transmitted to the spacecraft from 

DSN and were stored in its computer memories. For some time, the spacecraft cam

and other scientific instruments had been trained on the approaching planet; engin

ing and the telemetry data rate had been increased to the maximum possible. All 

terrestrial communications circuits linking the three Deep Space Complexes to JPL w

on high alert. The Deep Space Network was then doing what it does best: providin

real-time, two-way, coherent, digital data communications link between NASA’s 

x

Introduction
Propulsion Laboratory in Pasadena, California, and a planetary spacecraft encounte

one of the Jovian planets.

Responding to its stored commands, the spacecraft executed the encounter sequenc

events according to a pre-determined plan that included all of the onboard science ins

ments. As the spacecraft entered occultation (was obscured by the planet), radio scie

experiments were carried out using the spacecraft USO. The immense amount of 

collected in the short time of its actual encounter was stored by the spacecraft on 

tape recorder for later playback via the downlink. Only the most important data co

be sent back in real time, but this was sufficient to give anxious mission scientists t

first glimpse of the planet, up close. Even after demodulating and decoding the do

link data stream that contained the images, the tracking stations could not view th

They had to be separated from the other science data and further processed by c

puters at JPL before they could be analyzed by the imaging team and presented 

public viewing.

It was those pictures that the public first saw on television at the early NASA press c

ferences from JPL. Later, as the remainder of the encounter data were retrieved by 

DSN, scientists conducted much more detailed analyses of their data and their find

were ultimately presented to the world at NASA press conferences in Washington. 

DSN stations continued to track the spacecraft as it pursued its orbit around the S

returning science data at an ever decreasing rate and conducting radio science exp

ments as the opportunity arose. So long as the spacecraft continued to function prop

scientists continued to press for more data from deep space, and for the support of 

Deep Space Network to obtain it.

The foregoing end-to-end scenario established the DSN as an essential part of 

answer to the questions invoked by a search for a less obvious connection between 

launch of a spacecraft and science data presented at a NASA press conference. Perh

that answer begets further the question of how the DSN came into being and how 

developed. With that question in mind, what a timely open to the history of the D

Space Network. 

xlviii

Uplink-Downlink: A History of the Deep Space Netw
Chapte

Genesis: 1957–196
GOLDSTONE, CALIFORNIA

A fine, wide, blacktop road runs past the salt-encrusted bed of dry lake toward the M

site at Goldstone, deep in California’s Mojave Desert. Opposite the lake bed off to 

right, a disused minor road leads through a narrow cleft in the desiccated, brown 

brick red-colored landscape to another dry lake bed, surrounded by low, barren hills 

also encrusted with dried salt. There is nothing else here except for a small brick bu

ing and an unusual, spidery, three-legged structure supporting a large, perforated m

dish. The open side of the dish faces the sky, and high above its center, a smaller 

is suspended at the apex of four tall struts protruding from the surface of the large d

Although the immensity of the totally barren landscape dwarfs the whole structur

is, in fact, well over thirty meters to its highest point. A chain link fence encloses 

area, and a bronze tablet on the nearby stone marker informs the occasional visitor 

this is the site of the NASA Pioneer Deep Space Station. The inscription on the plaq

overlaid on the photograph of the Pioneer site shown in Figure 1-1, identifies the 

tion’s association with the NASA space program.

Uplink-Downlink: A History of the Deep Space Netw

2

Genesis: 1957-1961

Figure 1-1. View of the Pioneer tracking station site, Goldstone, California, 1978. The 

entrance to the site is on the far side of the picture, while the antenna, seemingly diminished 

the immensity of surrounding landscape, stands in the center near the edge of the lake bed.
Several of the people who played a prominent part in the establishment of the orig

Network attended the dedication ceremony. They appear in the unveiling picture sho

in Figure 1-2. Their role in the chronicle of the Deep Space Network (DSN) will beco

apparent in later chapters.

This antenna, built in 1958, known through most of its working life as Deep Sp

Station 11 (DSS 11), was the first antenna in what eventually became the NASA D

Space Network. As the inscription of the plaque implies, it supported all of the NA

deep space missions during the twenty years of its operational life.

At deactivation in 1981, Station Director Lou Butcher sent a message to his colleag

throughout the Network which neatly summarized the Station’s long association w

the NASA space program: “The closing of the Pioneer (DSS 11) station marks the 

of 23 years of spaceflight tracking. DSS 11 was built when the Jet Propulsion Labora

Genesis: 1957–1961

Figure 1-2. Prominent personalities of the Deep Space Network unveiling the commemora

plaque at the Goldstone Pioneer Site, 28 October 1978. Eberhardt Rechtin, principal founder o

Deep Space Network, is on the right. William H. Bayley, the original General Manager of the Netw

is on the left. Richard K. Mallis, DSIF Operations Manager, is standing next to Bayley. Charles Kosci

Director of the Goldstone Complex at the time of the dedication ceremony, is next to Rechtin. 
(JPL) was under contract to the Army and was the first 26-meter antenna to be b

in the DSN. DSS 11 was the leader for all DSN stations to follow in tracking the 

JPL space mission (Pioneer 3) in December 1958. It was the station that tracked Surv

1 onto the Lunar surface, and the station that tracked the lunar module (Apollo 

onto the Lunar surface. It has played a major role in most of the NASA Lunar 

Planetary spaceflight achievements.” The United States Department of the Interior 

ignated the Pioneer site as a National Historic Landmark on 27 December 1985. I

very literal sense, this is where the history of the Deep Space Network began.

The International Geophysical Year (IGY)1, 1957, a cooperative international enterp

to advance the state of scientific knowledge about Earth and its environment, commen

in July and was running its course. In October, the Russians launched the world’s 

Earth-orbiting satellite, called Sputnik, as part of their contribution to the IGY activi

About a month later, Soviet scientists launched a larger version of Sputnik containin

live dog, named Laika, into a high elliptical orbit around the Earth. Both in and ou

government, scientific, and engineering circles, the effect of the Sputnik launch was 

of complete surprise, followed by damaged pride and embarrassment. From a mili

viewpoint, the implications were obvious: the Soviets demonstrated an operational, in

continental ballistic missile (ICBM) capability ahead of the United States. While to 

scientific world at large, Soviet science was clearly leading the “race to space,” the ho

of U.S. scientists were pinned on Project Vanguard, a U.S. Navy project to place a gr

fruit-sized scientific package in Earth orbit. In full view of a national television audie

the first Vanguard launch at Cape Canaveral in December 1951 was a complete fail

enhancing even more the prestige of the Soviet accomplishment with Sputnik.

The U.S. government was engaged in a desperate “catch-up” game with its Soviet co

terpart in the newly emerging field of space research.

The events that followed the December Vanguard debacle are the stuff of which the 

tory of JPL is made, but to properly appreciate what happened next, one needs to m

a short backtrack to 1955.

As a consequence of a lengthy experience with the U.S. Army as a contractor on various g

ed missile development programs at the White Sands Missile Range, JPL had already develo

a great deal of expertise in the techniques and technology of guidance and tracking systems 

large rockets and ICBMs. While working for the Army as long ago as 1955, JPL, in com

tition with the Navy and the Air Force, submitted a proposal for an Earth-orbiting satellite 

the U.S. contribution to the IGY. JPL’s satellite was to be called Orbiter. The Departmen

Defense (DOD), however, selected the Navy’s proposal called Vanguard, and JPL’s Orbiter 

Uplink-Downlink: A History of the Deep Space Netw

4
posal was shelved. Perhaps it was serendipity, but the U.S. Army encouraged JPL to cont

with development of Orbiter, at a low level, for the next couple of years. High-speed up

stages for the booster rockets were developed and guidance and telemetry systems were desig

and tested. Of particular significance to the then-distant future of a deep space tracking 

work was the tracking system designed by JPL to track the high altitude test rockets. It 

called Microlock, and working in conjunction with a minimum weight radio transmitter 

ried by the flight test unit, could provide telemetry and positional data to a range of sev

thousand kilometers. A phase-lock tracking receiver, a key feature developed at JPL by Eberh

Rechtin and Richard Jaffe some years earlier, was operational at each of the Microlock stati

Toward the end of 1957, perhaps sensing that the Vanguard program was in trou

Secretary of Defense Neil H. McElroy authorized the Army to reactivate the Orb

program and proceed with all deliberate speed to an earliest possible launch. The A

provided a launch vehicle based on an existing Redstone rocket design and JPL p

vided a suitable satellite carrying a small scientific payload, including a radiation-measu

instrument designed by Dr. James A. Van Allen of the University of Iowa. The sate

was renamed Explorer and the Army-JPL team was committed to launch in 90 da

To track the new satellite and to receive its downlink telemetry signals, JPL expan

its existing Microlock ground-based tracking facilities to include stations at Cape Canav

Singapore; Nigeria; and San Diego, California. Primitive communications services to 

overseas sites sometimes relied on native “runners” to transport messages and tape

the nearest telegraph office. Although the U.S. stations had interferometric tracking an

nas, a single, helical antenna at each overseas site provided only telemetry and Dop

data. Primitive though it was, JPL had acquired its first taste of worldwide netw

development and operations.2

On 31 January 1958, less than 60 days after the Vanguard explosion on the launch p

and just 84 days after receiving approval from Secretary McElroy, Explorer I lifted 

the launch pad at Cape Canaveral atop a Juno I launch vehicle and, to the acclaim 

a national television audience, became America’s first Earth-orbiting satellite. Telem

data received by the Microlock ground stations from the Van Allen Geiger-coun

revealed the presence of a high altitude band of radiation encircling Earth. Eventu

named for Van Allen, this became one of the most important discoveries of the IG

Suddenly, the “catch-up” roles of the previous year were reversed and JPL never loo

back. Henceforth, attention was focused not on the near-Earth region but outw

toward deep space, and its chief advocate was the ambitious and far-sighted directo

JPL, William H. Pickering.

Genesis: 1957–1961
Knight Commander of the British Empire, conferred by England’s Queen Elizabet

in 1975, is among the many honors and citations bestowed upon William Pickering 

prestigious scientific and technical organizations throughout the world. Knighthood 

only recognized his scientific achievements, but also symbolized his British heritage 

association with his native country of New Zealand. Pickering received his formal h

school education in Wellington, the capital city of New Zealand, prior to embarking 

a career in electrical engineering at California Institute of Technology (Caltech) in Pasad

California, in 1929. Seven years later, he had earned a Ph.D. in physics and an appo

ment to the Caltech faculty, where, in addition to teaching, he was engaged in cos

ray research with Robert A. Milikan and H. Victor Neher.

During World War II, Pickering organized and taught electronics courses for mili

personnel at Caltech, and became acquainted with the Radiation Laboratory at M

and its director, Lee A. Dubridge. By the time Dubridge was named to the preside

of Caltech in 1946, Pickering was working at Caltech’s Jet Propulsion Laboratory 

the design and development of telemetering systems for rocket research vehicles. Picke

was appointed director of JPL in 1954 and immediately began moving the labora

toward the forefront of applied engineering research and development. Within a 

short years, the results of this move became apparent to the world-at-large in a sp

tacular way. The Explorer I Earth-orbiting satellite, the United States’ initial respons

the Soviets’ Sputnik, made its appearance in January 1958, thanks to the combi

efforts of the teams led by Pickering (satellite), von Braun (launch rocket), and 

Allen (radiation measuring experiment).

Following this spectacular success, historian Cargill Hall described Pickering as, “sp

intense, reserved, and in a quiet way, implacable . . . determined to mount a JPL p

gram of lunar flights. To his mind,” he said, “lunar flights might once have bee

subject fit only for science fiction, but now they were on the reachable frontier of e

neering science, exactly the frontier where Pickering wanted JPL to be.” Prophetic w

indeed. As director of what soon became a NASA Field Center, Pickering led JPL thro

the highs and lows of the first U.S. spaceflights to the Moon, and later, to Venus 

Mars. Under his leadership, NASA/JPL, part of which included the Deep Space Netw

quickly established and maintained a position of pre-eminence in the emerging, new 

of science and technology for deep space planetary exploration.3

He retired from JPL in 1976 and served for two years as director of the research in

tute of the University of Petroleum and Minerals in Saudi Arabia. He later returned 

Pasadena to enter private consulting practice.

Uplink-Downlink: A History of the Deep Space Netw

6
The Pioneer Lunar Probes

On 7 February 1958, responding to President Eisenhower’s initiative for a United St

Space Program, the Department of Defense established an organization called the Advan

Research Projects Agency (ARPA) to promote, coordinate, and manage all existing 

itary and civilian space activities. ARPA was to function only as an interim organiza

pending congressional establishment of a civilian space management agency.4

Toward the end of March 1958, the Secretary of Defense announced approval of a lu

space program, to be directed by ARPA as part of the United States’ participation 

the International Geophysical Year (IGY) activities. The program was named Pione

The Pioneer lunar program involved three launches by the U.S. Air Force, using 

existing Thor-Able booster rocket combination, and two U.S. Army launches utili

the new Jupiter Intermediate Range Ballistic Missile (IRBM), designated as Juno II. 

scientific objectives of the Pioneer program were to measure cosmic radiation in 

region between Earth and the Moon, and to make a more accurate determination 

the mass of the Moon. At the same time, valuable experience in the design of a lu

probe trajectory and a tracking and telecommunications system could be obtained. Bec

of its long prior association with the Army’s missile development programs at W

Sands Missile Range, JPL was to be involved in the two Army launches, Pioneers 3 

4. The target launch dates were set for 11 November and 14 December 1958.

Research into the tracking and communications systems required to support a space p

gram of lunar and planetary spacecraft had been in progress at JPL for some time.

Confronted with the problem of tracking and communicating with the two Pion

probes, JPL put that fund of knowledge to good account.

At that time, JPL was fortunate to have, as the head of its small missile guidance resea

division, a visionary whose advocacy of the long term approach determined the co

of U.S. solar system exploration far into the future.

Tall, imposing in appearance, of quiet disposition and authoritative manner, Eberh

Rechtin was the epitome of the top-level executive. Articulate, with a brilliant e

neering mind, he seemed to be way ahead of other the speaker in a conversation

the presenter at a conference. He was patient with those less acute in their think

and courteous in pointing out errors of fact or judgement. A dark suit and tie c

pleted his picture. He was also, not surprisingly, an accomplished violinist.

Genesis: 1957–1961
Eberhardt Rechtin brought a B.Sc. degree in electrical engineering (1946) from the Califo

Institute of Technology with him when he joined JPL in 1946 as a member of the 

talented communications and radio guidance team on the Corporal and Sergeant p

grams. He completed a Ph.D. in electrical engineering at Caltech in 1950 and along w

Richard Jaffe, went on to study the theory and design of “phase-lock” circuits. With W

Victor’s help, the basis of the “phase-lock” receivers became an integral part of the DS

As the first head of the Tracking and Data Acquisition Office at JPL, it was Rech

vision of a worldwide network of tracking stations, and his considerable powers of 

suasion and tenacity in pursuing his ideas with NASA, that gave impetus and direc

to the DSN in the early formative years. It was his endorsement that gave substanc

the far-reaching proposals of Victor, Stevens, and Merrick for the new 64-meter an

nas that would be much larger and perform better than any existing antennas desig

for tracking distant spacecraft. He introduced the concept of the “sum of the nega

tolerances” as the standard criterion for the margin of safety in the design of upl

and downlinks for planetary spacecraft. To control the electrical interfaces (uplink 

downlink) between the DSN and the many different JPL and non-JPL designed sp

craft that he perceived would require tracking support from the DSN in the years ah

he mandated fixed, definable specification for the DSN radio links. This would beco

a permanent and vital feature of DSN management in the years ahead.

Father of the phase-lock loop and architect of the DSN were his legacies. Rechtin ret

from JPL in 1967 to head the Advanced Research Projects Agency of the U.S. Departm

of Defense.

It was the perception of Eberhardt Rechtin that solar system exploration should conti

to evolve in coming years and eventually become a major part of the overall NASA sp

program. He envisioned not only a lunar program which included soft landings on 

Moon’s surface, but also a program that involved a photographic survey of Venus and M

A long-range vision such as his required not one, but three antennas spaced at 120 deg

of longitude around Earth so that they could maintain continuous contact with the sp

craft as Earth rotated about its axis. Although time and funding precluded the full-s

plan, for the immediate task of tracking the Pioneer lunar probes, one antenna suffi

It did not allow for continuous contact with the probe, but the time of launch and 

jectory could be arranged so that the actual flyby occurred when the probe was in v

of the single antenna site. Later, assuming approved appropriate funding, the additi

antennas could be added to create the full network and give the U.S. the capability 

communicate with future spacecraft travelling to the edge of the solar system.

Uplink-Downlink: A History of the Deep Space Netw

8
To lend credence to his ideas, Rechtin gathered experts in all the fields of techno

necessary to accept a challenge of those dimensions.

Victor, Stevens, Merrick, and Bell, each an expert in his own field, had the knowle

and drive to lead the way in developing and building the super-sensitive receivers, tele

try and guidance systems, high power transmitters and large precision antenna structu

all needed on a very short time scale.

Immediate decisions were needed on basic communications parameters, such as ope

ing frequency, antenna gain, antenna diameter, beamwidth, angular pointing accur

slew rate, receiver sensitivity, Doppler tracking rates, bandwidth, transmitter power, 

signal-to-noise ratios. Similar parameters were needed for the probe radio system so 

the probe and Earth communications systems continued to work together as the 

tance between them stretched as far as the Moon and beyond.

The team had already determined that the existing ground-based tracking systems, wh

were being used by JPL for the Earth-orbiting Explorer flights in progress at that ti

were not suitable for tracking lunar probes. A more efficient, high-performance, Ea

based antenna was needed. After considerations of antenna gain, automatic track

performance, minimum galactic radio noise and the state-of-the-art radio communicat

at that time, a frequency of 960 MHz was chosen as near-optimum for the commun

tions link between the lunar probe and Earth. The Pioneer radio transmitter transmi

at 960 MHz and the Earth-based tracking station received on that frequency. A la

diameter, steerable, parabolic dish antenna capable of operating at 960 MHz was nee

to receive the transmissions from the Pioneer probes and be available for the suppor

possible follow-on missions, perhaps even for missions beyond the Moon to the nea

planets. The launch dates were set for yearend. Cost and construction time were vital 

tors in the search for a suitable antenna. While incorporating advanced and reliable princi

of design, the antenna was to be built and operating in approximately six months.

The choice of 960 MHz as the operating frequency for the Pioneer probe brought w

it another most significant advantage. It allowed JPL to make use of an existing de

for a large radio astronomy antenna developed some years earlier for the burgeoning 

ence of radio astronomy by the Naval Research Laboratory, with assistance from 

Carnegie Institute, Associated Universities, and the Blaw-Knox Company. As a resul

this prior work, the Blaw-Knox Company could provide a large parabolic antenna 

would meet the fixed price and construction time constraint of six months. 

antenna, 26 meters (85 feet) in diameter, was designed for radio astronomy applicati

Genesis: 1957–1961
and required substantial modifications to the antenna drive system to make it suit

for precision tracking of lunar space probes.

Confident in JPL’s ability to make the necessary changes and get the antenna built 

operating in time for the Pioneer 3 launch, ARPA decided to purchase not one, 

three, of the 26-meter antennas. One of the antennas would be used for the immin

Pioneer launches, while the other two were intended for ARPA longer range plans 

what it termed its World Net. It was a calculated risk on the part of ARPA, for e

though the design was complete, none of the antennas had yet been built. With 

pressure of the Pioneer launch schedule, however, there was little choice in the ma

With the operating frequency and antenna decisions already made, attention turned 

a location for the antenna site. To avoid contaminating or obscuring the very weak ra

signals received from the distant spacecraft with artificial radio interference, a loca

remote from any metropolitan area was desired. At the same time it needed to be c

enough to an established community to be practical for the staff that would be requ

to operate the equipment. The combined constraints of funding and schedule stron

influenced a search for a suitable site on Government-owned property. A conven

location that met all of these criteria was found in a natural bowl-shaped area surroun

by low hills near the Goldstone Dry Lake on the Fort Irwin military reservation, 

kilometers northwest of the city of Barstow, in the Mojave Desert, California.

In March 1958, a JPL radio interference survey team certified the area as free from ra

interference. A month later a construction company began work on access roads, f

ities, services, and buildings. While work was in progress at Goldstone, a mobile track

station, using a three-meter diameter antenna, was erected near Mayaguez, Puerto R

to obtain initial trajectory data downrange from the Florida launch site.

In early June, the steel components for the antenna started to arrive onsite at Goldsto

Assembly of the antenna commenced in mid-August and was completed in Novem

1958. By that time, all the receiving, recording, communications, servo, and ante

drive modifications and other electronics had been installed and tested. After a short p

od of crew training, the station was ready for its first operational mission, but there 

been no time to spare. A photograph of the first Goldstone antenna, as it looked sh

ly after beginning operation in 1958, is shown in Figure 1-3.

While the antenna construction work was proceeding on an accelerated schedul

Goldstone, the direction of the space program was changing rapidly in Washing

President Eisenhower’s Executive Order No. 10783 officially established the Natio

Uplink-Downlink: A History of the Deep Space Netw

10
Aeronautics and Space Administration (NASA) on 1 October 1958. Discussions reg

ing the status of the Jet Propulsion Laboratory and its possible acquisition by NASA 

a component Field Center quickly followed.

NASA outlined its proposal for the transfer of JPL from the Army on 15 October 19

A few weeks later, the Department of Defense indicated acceptance of the proposal 

on 3 December 1958, Presidential Order No. 10793 transferred the functions and f

Genesis: 1957–1961

Figure 1-3. The 26-meter antenna and tracking station (DSIF 11) at Pioneer site, Goldst

California, 1958. Pioneer, the first Goldstone antenna as it looked shortly after beginning op

tion in 1958. The antenna was deactivated in 1981 and has been designated a National His

Landmark by the U.S. Department of the Interior.
ities of the Jet Propulsion Laboratory of the California Institute of Technology from 

Department of the Army to NASA.

NASA launched Pioneer 3 on a trajectory toward the Moon three days later, 

6 December 1958. Due to a rocket booster problem, the probe only reached an altitud

63,500 miles before falling back to Earth, somewhere in central Africa. The small ante

in Puerto Rico tracked it for 14 hours (round-trip) and was able to maintain telemetry c

tact to at least 60,000 kilometers. The much larger Goldstone antenna was able to acq

telemetry for the entire time that the Pioneer 3 probe was above its horizon. The telem

received from the Puerto Rico station proved to have significant scientific value becau

contained the data from two passes through the then-mysterious Van Allen radiation b

Although the Pioneer 3 flight was a disappointment, three months later, the next lu

probe, Pioneer 4, became the first United States spacecraft to leave Earth’s gravitati

field. Launched on 3 March 1959, on a trajectory similar to that of Pioneer 3, the pr

traveled 435,000 miles toward destination before its batteries became depleted and its tr

missions to Earth ceased. After 41 hours of flight, Pioneer 4 passed 37,300 miles from 

Moon’s surface on a flight path that was a good deal ahead of and below the planned 

jectory. Although one of the key experiments to observe the hidden side of the Moon 

defeated by the perturbed trajectory, data from the onboard radiation counters identi

a third belt of radiation and sensed significant changes in the intensity of the Van A

radiation belts discovered by Pioneer 3. With its large antenna working well, the Goldst

station recorded over 24 hours of telemetry data from three successive 10-hour passes 

the site, before the signal ceased during the fourth pass on 6 March 1959.

While the Pioneer 3 and 4 missions had not been entirely successful, the performa

of the new antenna exceeded all expectations. It demonstrated the efficacy of its de

and fully vindicated the confidence that ARPA had shown in JPL’s expertise and a

ty to accomplish a challenging task. It would henceforth be known as the Goldst

Pioneer tracking station, identified as DSIF 11.

The Echo Balloon Experiment

Important and highly visible as they were, the Pioneer 3 and 4 lunar probes were not 

only projects that engaged the attention of Rechtin and his engineering team at JPL 

the spring of 1959. In January, JPL had agreed to cooperate with NASA and Bell Teleph

Laboratories (BTL) of Holmdel, New Jersey, in an experiment to test the feasibility 

long-range communications between two distant points on the surface of the Earth 

means of a reflected signal from the surface of a large orbiting balloon. Based on sepa

Uplink-Downlink: A History of the Deep Space Netw

12
and independent proposals from scientists at BTL, who were interested in studying 

use of “passive repeaters” for radio communications, and scientists at the Lan

Aeronautical Laboratory in Hampton, Virginia, who were interested in air density m

urements in Earth’s upper atmosphere, this experiment, named Project Echo, was endo

several years earlier by the United States IGY Committee. Scientists had agreed on a de

for an experiment to satisfy both scientific objectives. A radio signal would be transm

ted from the east coast of the United States, reflected off the metalized surface of a l

(100-foot diameter) Earth-orbiting balloon, and received on the west coast. A similar l

using a much higher frequency, would be set up in the west-to-east direction. The p

called for setting up separate links at 960 MHz (east to west) and 2,390 MHz (wes

east). The essential features of the experiment are shown in Figure 1-4.

In the fall of 1958, while considering how the Echo balloon experiment might be im

mented, it became apparent to engineers at JPL that the new antenna, then un

construction at Goldstone, could serve as the west coast receiving terminal for the 9

MHz, east-to-west leg of the experiment. For its part, BTL would provide a 960-M

transmitting station and a 2,390-MHz receiving station at its east coast facilities in N

Jersey. However, one major problem remained unsolved. There was no transmitter 

Genesis: 1957–1961

Figure 1-4. Essential features of the Project Echo Experiment, 1960.

100 ft

GODDARD SPACE FLIGHT CENTER

COMPUTER

WASHINGTON, D.C.

BELL TELEPHONE LABORATORIES

HOLMDEL, NEW JERSEY

POINTING

DATA

POINTING

DATA

JET PROPULSION LABORATORY

GOLDSTONE, CALIFORNIA

RECEIVER

10-kW

TRANSMITTER

10-kW

TRANSMITTE

RECEIVE

EARTH

ECHO 1 BALLOON

HORN

2390 MC

960 MC

80-ft DISH

1,000 MILES 85-ft DISHES

2390 MC

960 MC
Uplink-Downlink: A History of the Deep Space Netw

14

the 2,390-MHz for the west-to-east leg of the experiment. The new Goldstone an

na was designed as a receiving station only. It had no transmit capability.

To solve that problem, a second 85-foot antenna was built at Goldstone in 1959 u

funds provided by the NASA Communications Satellite program. To avoid mutual ra

interference between the two antennas, a site some miles away but similar to the Pion

site was selected. A low range of hills separated the two sites and provided the ne

sary level of radio isolation between them. JPL named the site “Echo” for its obv

association with the Echo experiment.

An early photograph of the transmitting antenna at the Goldstone Echo site is sho

in Figure 1-5.

Unlike the Pioneer antenna, which used a polar or hour angle-declination (HA-D

drive system, the Echo antenna used a high-speed, azimuth-elevation (Az-El) drive wh

was more suitable for tracking Earth satellites, such as Echo, than the more astrono

Figure 1-5. Az-El transmitting antenna for the Echo Balloon Experiment, Goldstone, 1

The antenna was constructed between July and December 1959, and the complete station bec

operational in July 1960.
oriented polar drive used for deep space probes. The Echo station also included a 

kilowatt transmitter operating at 2,390 MHz, which at the time represented a v

advanced, state-of-the-art development. In addition to supporting the Echo balloon ex

iment, the advanced features of the Echo station allowed JPL engineers to evaluate 

relative merits of large antenna drive systems and the performance of high-power tr

mitters and low-noise receivers, operating at S-band, for future applications in deep sp

tracking stations.

Less than a month after the full station was completed, on 12 August 1960, Echo 1 

launched. Within two hours of launch, a recording of President Eisenhower’s voice 

transmitted from the Echo site at Goldstone to BTL in New Jersey. Echo had score

“first” in long distance passive reflector communications. Ironically, this distinction 

almost immediately eclipsed by the informal Goldstone to Woomera “moon-boun

experiment described later in this chapter. Experiments in long distance communicat

and upper atmospheric air density soon followed.

At the conclusion of the Echo experiment, ownership of the Echo antenna was tr

ferred to the new NASA Office of Tracking and Data Acquisition and became an off

part of the Deep Space Instrumentation Facility. Its ultimate destiny, however, lay 

different direction from that of Pioneer, the other DSIF antenna at Goldstone. The 

step along this path began with the Venus Radar Experiment in March 1961.

The Venus Radar Experiment

The possibility of detecting an Earth-based radio signal reflected from the surfac

Venus had intrigued radio astronomers through most of the 1950s. In fact, invest

tors at Lincoln Laboratory, Massachusetts Institute of Technology, and at Jodrell B

Experimental Station, University of Manchester, had attempted to detect echoes f

Venus in 1958 and 1959 without success.

A successful experiment of this kind could offer great potential for a plethora of 

scientific knowledge about Venus and its physical properties, and the possibility, 

example, to determine the reflective properties of the surface for electromagnetic ra

tion, the orientation of the planet’s axis of rotation, and its rate of rotation. Also, m

could be learned about the characteristics of the interplanetary medium along the tr

mission path between Earth and Venus. Most importantly though, it could offer 

possibility to independently determine a value for the astronomical unit (AU) with m

greater accuracy than had been previously possible.

Genesis: 1957–1961
The astronomical unit (AU), used by astronomers as a measure of the mean distanc

Earth from the Sun, is a vital parameter in the calculation of the ephemerides, or 

paths of planets around the solar system. It was therefore of immense significanc

JPL’s long-range plans for sending spacecraft on missions to close encounters with 

tant planets. JPL engineers viewed the Venus radar experiment as a technological challe

for the type of equipment required for future missions to the planets and for person

to operate it. Without the very highest level of performance in both areas, the hope 

success would be minimal, and would establish a standard against which the perfo

ance of future operational DSIF stations could be judged.

During the experiment, a 13-kilowatt, continuous wave, S-band signal was transmitted f

the new Echo antenna toward the planet, while the reflected signal was received by 

Pioneer antenna fitted with a Maser receiver, specially designed for reception of very w

signals. The first undisputable radar returns from the planet Venus were obtained with 

Goldstone radar on 10 March 1961. Using advanced, spectrum analysis techniques, the r

team, led by Richard Goldstein, measured the delay to, and changes in, the fundame

character of the returned signal due to its round-trip to Venus and back to Earth. These 

were recorded for subsequent scientific analysis. During the time that Venus remained w

in 50 and 75 million miles from Earth, over 200 hours of good radar data were obtain

After analysis, this impressive bank of scientific data yielded the much sought after “impro

value for the AU” in addition to satisfying the several other scientific objectives of 

experiment. The new value for the AU was determined to be 149,598,500 ± 500 km

most significant improvement in the accuracy of previous values.6 Subsequently, JPL 

mated that Mariner 2, the first mission to Venus the following year, would have mi

the planet by too great a distance to have been of any scientific value, had the old v

of the AU been used in the trajectory computations.

The Venus radar experiment thus represented the first use of the DSN (DSIF) as a 

entific instrument. Its immediate success marked the appearance of a signific

astronomical research tool at Goldstone, whose stature in the scientific community wo

continue to rise as the years went by. The technical details of the Venus radar exp

ment, and the history of what evolved into the Goldstone Solar System Radar, is descri

in chapter 8, “The Deep Space Network as a Scientific Instrument.”

Research and Development Antenna

By the time the Venus radar experiments ended in May 1961, it had become appa

that JPL communications engineers needed a dedicated antenna research and deve

Uplink-Downlink: A History of the Deep Space Netw

16
ment facility at Goldstone, where new components used in the network could be t

ed, measured, and evaluated. With the pressing needs of future missions in mind, 

the Ranger and Mariner missions about to start, it was simply not possible to dev

one of the two existing Goldstone antennas (Pioneer or Echo) solely to research w

despite the vital importance to the technological future of the network. Prediction

future mission requirements mandated a need for two operational antennas, not onl

Goldstone, but also at the other two longitudes.

Furthermore, until a way could be found to simultaneously transmit and receive on a 

gle antenna without severely degrading the downlink signals, two antennas, one for transmit

and the other for receiving, would be required for deep space communications.

On this basis, the case was made for yet another antenna at Goldstone. The new an

na, which would be of the same type as the Pioneer and two overseas antennas, wo

be erected at the Echo site where it could make use of the existing support facili

When that was completed, the original Echo Az-El antenna would be moved to an

er site a few miles away, and established as the basis for a new facility dedicated to d

space communications research and development (R&D).

The plan was rapidly approved by NASA and immediately put into effect at Goldsto

Between February and May 1992, a new HA-Dec antenna was erected near the A

antenna at the Echo site. It was put into service two months later, just in time to s

port the first Mariner missions to Venus.

With a second operational deep space station now in place at Goldstone, the Az-El an

na could be released from network support and prepared for the complex task of relocati

In June 1962, the entire Az-El antenna—mounted on its pedestal—was jacked up, loa

on a supporting undercarriage, and moved approximately four miles across the deser

a new location that became known as the Venus site, after the now famous Venus ra

experiment. There, the antenna began a brilliant new life as a test facility for com

nications research and development, and over the next 40 years, proved vital to 

continued preservation of JPL pre-eminence in the field of deep space communicati

The research work that was conducted at that facility, known through the D

R&D Station 13, is described in chapter 7, “The Advance of Technology in 

Deep Space Network.”

Genesis: 1957–1961
WASHINGTON, DC

Before proceeding further with the history of the DSN, it will be instructive to rev

the events occurring simultaneously in a related but quite different arena from that 

described. The focus of that activity was in Washington, DC.

Before NASA was created, ARPA had planned to develop a worldwide network of tr

ing stations to support its forthcoming programs for the exploration of deep space. 

network was to be called Tracking and Communications Extraterrestrial Network (TRAC

Starting with the first three TRACE stations—Goldstone, Puerto Rico, and another sm

station at Cape Canaveral—ARPA planned to expand TRACE into a full-scale wo

wide network by adding two additional overseas stations, similar to the one it had fun

for Goldstone. This expansion was the rationale for the ARPA decision to purchase th

of the 85-foot-diameter antennas from Blaw-Knox in 1957.

Plans for the worldwide network were well under way in early 1958. ARPA had alre

approved a JPL proposal for a three-station network which would provide optimum 

erage for tracking deep space probes. One of the sites would be sites at Goldsto

California. The two overseas stations were to be located at Luzon, the Philippines, 

in Nigeria.8

Taking a broader view, however, the Department of Defense expressed some reservat

about the proposed sites in terms of their utility to all U.S. space vehicles, rather t

the specific, deep space probes considered by JPL. With this in mind, ARPA asked 

to reconsider its proposal for the station sites with the object of improving coverage 

a broader range of space vehicle trajectories. The resulting study showed that be

orbital coverage for all planned U.S. space missions would be possible if the Nige

site was moved north to southern Portugal or Spain, and the Philippines site mo

south to central Australia. The coverage of orbits with an inclination of 34 degree

51 degrees would be much improved. Future, piloted, Earth-orbiting flights were v

much in the minds of the planners at the time.9 In retrospect, their foresight was 

justified since these locations effectively served the needs of the major tracking stat

of the Deep Space Network for over forty years.

In the turmoil of space-related activity in that tumultuous year, 1958, ARPA never 

get the opportunity to deploy the overseas stations of its World Net. NASA was cr

ed in October of that year, JPL was transferred to NASA in December, Pioneer 3 

launched, and by the opening of the new year, 1959, it was NASA and not ARPA 

ting the course for JPL and the future shape of the Deep Space Network. It was NA

Uplink-Downlink: A History of the Deep Space Netw

18
that ultimately acquired and erected the two remaining antennas procured by AR

To the nation’s space program, and to the work at JPL, the formation of NASA 

transparent. It was mainly a transfer of authority and funding for the existing progra

Instead of working under an Army Contract, JPL now worked under a NASA contr

NASA inherited JPL’s experienced personnel its facilities, including the new antenn

Goldstone and, perhaps most important of all, the JPL vision of a worldwide netw

of tracking stations for deep space probes. ARPA, representing military interests in sp

applications, pressed forward with its own programs under the direction of DOD.

As soon as NASA began to make its long-range plans for a civilian space program kno

the need for completion of what ARPA had called the World Net immediately bec

obvious. One station already existed at Goldstone and sites had been proposed for 

overseas stations. The antenna at Goldstone now belonged to NASA, but ARPA 

owned the remaining two of the three originally ordered from Blaw-Knox. In Janu

1959, NASA and ARPA representatives decided each agency would get one anten

The NASA antenna would be shipped to Australia as part of a three-station NASA o

ated network with sites in Goldstone (existing), South Africa, and Australia. ARPA wo

use its antenna as part of a deep space network for military purposes with station

Japan and Spain. However, the military interest in deep space soon faded and NA

was eventually able to purchase the third antenna from ARPA to form the basis fo

station in South Africa.

In moving toward the ultimate creation of the worldwide network, NASA directed 

principal efforts in 1959 toward onsite surveys of the locations that had been propo

for Australia and South Africa and the diplomatic negotiations that were necessary 

secure approval for their use.10 In both countries, NASA was able to secure the inte

of the government agencies—Australian Department of Supply (DOS)/Weapons Resea

Establishment (WRE) and the South African Council for Scientific and Industrial Rese

(CSIR)/National Institute of Telecommunications Research (NITR), respectively—in co

erating in the operation of the proposed deep space stations. Both WRE and NI

assisted the NASA/JPL survey team in identifying sites for the stations which met 

three major criteria; a stable land area capable of supporting large antenna structu

surrounding hilly terrain to provide natural shielding against electrical interference 

a surrounding area relatively free of radio interference in the frequency region useful 

space communications.

Genesis: 1957–1961
WOOMERA, AUSTRALIA

The favored Australian site lay on the southern edge of the great inland desert reg

at a place called Woomera, about 350 kilometers north of the city of Adelaide, cap

of the state of South Australia. Approximately 110 degrees west of the longitude 

Goldstone, Woomera was already a missile and long-range rocket test center oper

by WRE. The local language was English, and the nearby rocket and missile test ac

ities would provide a pool of technical expertise and facilities. Furthermore, in the s

area, the Australians had already installed, and were operating, a U.S. Navy minit

station and a Smithsonian Baker-Nunn tracking camera as part of its participation 

the IGY.

The signing of a “construction and operation” contract for the antenna around e

April 1960 allowed both JPL and WRE to begin making major moves toward c

struction of a NASA deep space tracking station at Woomera. WRE initiated the ro

buildings, power generation, and foundation work. JPL began shipping antenna c

ponents and the electronics for the station.

The antenna was finally built at a site known locally as “Island Lagoon,” so named 

the nearby dry lake which appeared to have an island at the center. Working und

JPL contract with supervisor Floyd W. Stoller, Blaw-Knox began assembling and er

ing the antenna in May 1960. By August, the antenna was complete and an electro

team began installing the radio and tracking equipment, most of which had been s

plied by Collins Radio Company. When NASA built the second and third 26-m anten

in Woomera, Australia, and Johannesburg, South Africa, the task of integrating the 

antennas with their electronics equipment and bringing the two new stations into o

ation fell to Richard “Dick” Mallis.

Richard Mallis was an outgoing individual, easy to work with, sociable, and much resp

ed by his colleagues. He was an excellent manager with good communications 

technical skills and an appreciation for the different institutional environments at 

three antenna locations. When he went to JPL in 1955 to work on radio guidance 

tems for the Army’s Sergeant missile program, native Californian Richard K. Mallis t

with him a degree in mechanical engineering from the University of Southern Califo

and a Navy background. Caught up in the changes that swept JPL into the space p

gram in 1958, he assisted with the construction of the first 26-m antenna at Goldsto

and later implemented the down-range tracking station in Puerto Rico to cover 

launches of the Army’s two Pioneer lunar probes.

Uplink-Downlink: A History of the Deep Space Netw

20
Together with Goldstone, the three stations of the Deep Space Instrumentation Fac

finally formed a worldwide network. With these completed in time to support JPL’s 

Ranger lunar missions, Mallis returned to JPL to take up a staff position in Renze

new Communications Engineering and Operations Section. He was responsible 

Operations, regulating the way the Network carried out its day-to-day tracking fu

tions. In this role, he set-up a Network-wide logistics and repair program, a freque

and timing standards program, a documentation system, and a training program 

operations and maintenance personnel. This essential infrastructure remained the b

for all operations, maintenance, quality control, and configuration management proc

es as the worldwide Network expanded in size and capability through the years. 

integrated the first commercial contractor, Bendix Field Engineering Corporation, 

the DSIF as the operations and maintenance service provider for the Goldstone fa

ty. In later years, as his responsibilities expanded to include the Space Flight Operat

Facility at JPL in addition to the DSN, he became Manager of the Operations Divis

Eventually he transferred elsewhere in JPL to further his professional career. Howe

because of his unique experience with service contract management, he was freque

called upon to assist the DSN in evaluating new contract proposals when existing s

ice contracts expired. He retired in 1993 after 37 years of service at JPL and later t

up residence in Australia.

In a final spectacular exercise on 3 November 1960, the Woomera station demonst

ed its operational status by receiving voice and teletype messages transmitted from Goldst

via reflection from the Moon. The JPL onsite manager, Richard K. Mallis, depa

Woomera four days later, after turning the new facility over to WRE for its future m

agement and operation. The Australian engineers soon demonstrated their ability 

handle the technical complexities of the new “space age” facility for which they 

accepted operational responsibility. In a repeat of the “Moon bounce” experiment on 

February 1961, during the official opening formalities, the station passed a congrat

tory message from NASA Deputy Administrator Hugh Dryden in Washington to Austra

Minister of Supply Alan Hume at Woomera over a “Moon bounce” communicat

link.

The photograph of the completed Woomera Tracking Station in Figure 1-6 shows 

26-meter-diameter antenna, the electronics equipment building, and service and fac

structures. Island Lagoon is visible at the horizon to the left of the antenna structu

The first overseas station of the Deep Space Instrumentation Facility (DSIF) was re

to enter operational service. Designated DSIF 41, Woomera, it would see eleven y

of valuable service before being superseded by new stations at Tidbinbilla, near Canbe

Genesis: 1957–1961
in southeast Australia. The Woomera station ceased operations on 22 December 19

as part of a NASA program to consolidate overseas station facilities. Initial proposal

move the antenna to a new, more accessible location where it could be used for Austra

radio astronomy purposes were not successful because the Department of Supply de

mined that the cost of transporting the antenna was excessive. Eventually, it was disman

and sold for scrap despite the vigorous protests of several prominent members of 

Australian scientific community.

Uplink-Downlink: A History of the Deep Space Netw

22

Figure 1-6. The 26-meter antenna and tracking station (DSIF 41), Woomera, Australia, 19
JOHANNESBURG, SOUTH AFRICA

The requirements for continuous tracking coverage of deep space probes outlined in 

JPL proposals for a worldwide network dictated that the third element in the netw

should be located in the longitude band which included Spain and South Africa. Altho

a site in Spain was preferred by NASA/JPL, the political complexities associated w

existing international treaties with Spain caused NASA/JPL to look to South Africa 

a suitable site. South Africa also offered many advantages. The South African gov

ment was anxious to participate with NASA in the new space venture, the language 

familiar, and a great deal of technical expertise was already available in that coun

Also, and most importantly, the flight path of all deep space probes launched from C

Canaveral would pass over or near the station within an hour or so of launch. T

meant that the downlink from the space probe could be first “acquired” close to 

point at which the spacecraft would be injected into its planetary trajectory. During 

period, mission controllers depended on telemetry and navigation data from the 

acquiring tracking station to make critical decisions very early in the mission, when 

rective action is necessary. Supplemented with the mobile tracking station that wo

be moved from Puerto Rico, an 85-foot antenna at this site would provide the D

with an excellent “initial acquisition” capability in addition to the normal tracking c

bility of the station.

The site that was chosen lay near the Hartebeestpoort Dam about 40 miles north 

Johannesburg, on government-owned property intended for use as a radio research f

ity. As had been the case at Woomera, a NASA Minitrack station and a Baker-N

camera were already operating in the vicinity. An earlier site survey confirmed that 

Hartebeestpoort site also satisfied the antenna site-selection criteria.

Although site surveys conducted in mid-1958 had confirmed the suitability of the 

for the antenna, it was not until September 1960 that an agreement between the g

ernments of the United States and the Union of South Africa permitted NASA to i

a contract to the South African Council for Scientific and Industrial Research for 

construction, management, and operation of the station. NASA wanted the station 

be completed by July 1961 in time to support the first launch of new Ranger miss

to the Moon. Time was truly “of the essence.” To prepare the site, erect the anten

install and test the equipment, and train personnel in its operation, under the pres

of a high profile mission like Ranger, posed a formidable challenge for everyone invol

Work began in earnest in mid-January 1961, as soon as the foundation for the an

na was ready. Antenna structural components travelling by ship, train, and truck f

Genesis: 1957–1961
Philadelphia had arrived a few days earlier. The erection team arrived from JPL a 

days later. Erection of the antenna finally began on 16 January and was completed 

days later on 25 March. The JPL team—Don Meyer, Dick McKee, and Howard Olse

completed installation of the electronics in early June and spent the next few w

conducting the necessary tests, checkouts, and calibrations. The station was ready 

operation by 1 July 1961. Provided with teletype equipment and communication 

cuits by the South African Department of the Postmaster General, the new station 

able to participate in the first operational readiness test for the Ranger missions late

July, as originally planned.

A photograph of the Johannesburg Tracking Station soon after its completion in 1

is shown in Figure 1-7.

Uplink-Downlink: A History of the Deep Space Netw

24

Figure 1-7. The 26-meter antenna and tracking station (DSIF 51), Hartebeestpoort, So

Africa, 1961.
JPL and South African officials discussed the possibility of holding a public even

mark the formal opening of the station as had been done for the Woomera stat

There was, however, some reluctance on the part of NASA Headquarters to pub

recognize a cooperative project with South Africa in light of the United States’ attit

toward the political situation then emerging in that country. Eventually, the South Afr

government held its own opening ceremony without formal NASA representation. So

years later, this issue would intensify and ultimately lead to the closure of the statio

a part of the Deep Space Network.

Nevertheless, the new station, designated DSIF 51, Johannesburg, played a vital rol

the early NASA missions to the Moon and planets. In that role, it served the DSN w

distinction for 13 years until DSN operations at that site were terminated in June 19

Soon after, NASA transferred the antenna and equipment to the South African Natio

Institute for Telecommunications Research (NITR) where it was used successfully fo

least another 25 years, as an instrument for radio astronomy research.11

The completion of the Johannesburg station marked the fulfillment of the world 

work initiatives proposed years earlier by JPL, carried forward under ARPA, and brou

to fruition under NASA. Together with a small launch monitoring facility at C

Canaveral, the three 85-foot antennas at Goldstone, Woomera, and Johannesburg bec

known as the Deep Space Instrumentation Facility (DSIF). The DSIF had becom

separate facility of the NASA Office of Space Operations. It was managed, technic

directed, and operated by the Jet Propulsion Laboratory (JPL) for the California Insti

of Technology (Caltech), a prime contractor for NASA’s Solar System Exploration p

gram, in Pasadena, California. Within a few years, the DSIF would change its nam

the Deep Space Network (DSN) and rapidly increase in size, complexity, and capa

ty to a level unimaginable to its founders. But that lay in the distant future. In 

immediate future lay the first operational challenge for the new network—the Ran

missions to the Moon and the first Mariner missions to Venus. It was to be a b

future. The Mariner Era was about to begin.

Genesis: 1957–1961
Endnotes

1. N. A. Renzetti et al., “A History of the Deep Space Network from Inception 

1 January 1969.” JPL Technical Report TR (September 1971): 32–1533.

2. William R. Corliss, “A History of the Deep Space Network” (Washington, D

National Aeronautics and Space Administration CR-151915, 1976).

3. R. Cargill Hall, Lunar Impact: A History of Project Ranger (Washington, D

National Aeronautics and Space Administration, 1977).

4. Homer E. Newell, Beyond the Atmosphere; Early Years of Space Science (Washing

DC: National Aeronautics and Space Administration SP-4211, 1980).

5. E. Rechtin and R. Jaffe, “The Design and Performance of Phase-Lock Circu

IRE Transactions on Information Theory (March 1955).

6. Andrew J. Butrica, To See the Unseen, A History of Planetary Radar Astron

(Washington, DC: National Aeronautics and Space Administration SP-42

1996): 42.

7. Jet Propulsion Laboratory, “Az-El Move and Reinstallation,” JPL Space Progr

Summary 37-13 (Vol. III, 1 October 1962): 9–13.

8. Jet Propulsion Laboratory, Description of World Network for Radio Tracking of Sp

Vehicles (Pasadena, CA: JPL Publication No. 135, 1 July 1958).

9. E. Rechtin, H. L. Richter, Jr., and W. K. Victor, “National Ground-Based Surveilla

Complex.” JPL Technical Memorandum TM 39-9 (15 December 1958).

10. Support for NASA facilities in Australia, South Africa, and Spain was provi

under cooperative international agreements between the United States and th

sovereign countries. The diplomatic, political, and administrative complexitie

the negotiations that culminated in those agreements is beyond the scope of 

history of the Deep Space Network. Readers interested in pursuing those details 

find useful material in the JPL and NASA Archives.

Uplink-Downlink: A History of the Deep Space Netw

26
11. A more detailed account of many of the topics discussed in this chapter is contai

in the unfinished and unpublished notes on the early (prior to 1962) history of 

Deep Space Network compiled by Craig Waff at JPL in 1993. The Waff notes 

held in the JPL Archives.

Genesis: 1957–1961
Chapter 

The Mariner Era: 1961–1974

2
THE MARINER ERA MISSION SET

The worldwide network, envisioned by Rechtin in 1958, became a reality betwee

July 1959 and July 1961. In that hectic two-year period, funding was proposed an

approved, international agreements were negotiated, suitable sites were found, equi

ment was procured and shipped overseas, roads and facilities were built, and JP

contractors erected antennas and installed equipment. The Deep Space Instrumentatio

Facility now consisted of a real network of 26-meter-diameter antennas located 

intervals of approximately 120 degrees of longitude around the globe. Two such ante

nas were located at Goldstone, California, and one each at Johannesburg, South Afric

and Woomera, Australia. A world view of the DSIF as it existed at that time is show

in the figure below.

30

Uplink-Downlink: A History of the Deep Space Networ

Figure 2-1. World view of the Deep Space Instrumentation Facility, 1961. Although the loc

tions of future sites, near Canberra, Australia, and near Madrid, Spain, are also shown on th

diagram, they had not been established at that time.
Teletype and telephone circuits linked the stations to a rudimentary flight operatio

control center at JPL. In the 1961 photograph of the operations control center 

JPL shown in Figure 2-2, the presence of rotary telephones, mechanical calculatin

machines, wall boards, and mechanical status displays is a poignant reminder of th

pre-digital age. 

At JPL and at each of the tracking stations, highly motivated crews of operators an

engineers were trained to operate and maintain the complex, state-of-the-art equipme

that JPL had designed and tested, but not yet demonstrated, to communicate with d

tant spacecraft. 

At the same time, DSIF planners knew that in the years ahead, the network would 

called upon to support much more complex missions to the Moon, missions to fly b

and possibly even orbit Venus and Mars, and heliocentric probes to measure fields an

particles and the solar wind in interplanetary space. At the extreme limit of possibili

lay spacecraft encounters with Jupiter and Saturn.

3

The Mariner Era: 1961–1974

Figure 2-2. Flight operations control center, JPL, 1961.
To appreciate the magnitude of the challenge facing the embryonic DSIF at that tim

it is instructive to arrange this inventory of future missions into a mission set in th

following way:

Deep Space Mission Set for the Mariner Era

Program Type Launches Missions First Launch Last Launch Span

Ranger Lunar Photo 9 3 Aug 61 Mar 65 4 yrs

Mariner Venus, Mars flyby 0 7 Jul 62 Nov 73 11 yrs

Pioneer Interplanetary 4 4 Dec 65 Nov 68 3 yrs

Jupiter 2 2 Mar 72 Apr 73 1 yr

Apollo Piloted 2 7 Test Nov 67 Dec 72 5 yrs

Lunar 14 6 Landers

Surveyor Lunar Lander 7 5 May 66 Jan 68 2 yrs

Lunar Orbiter Lunar Orbiter 5 5 Aug 66 Aug 67 1 yr

As this table makes clear, all launches did not necessarily result in successful mission

Failures were a common feature of the early programs but the failure rate greatly improv

as time went on. The Ranger program is an example. The launch span, the time betwee

the first and last launches of individual programs, is an indicator of the program’s impa

on the DSIF. Many launches in a short span affected the level of tracking activity f

the DSIF but did not require significant new technology between launches. Lunar Orbit

and Surveyor were such programs. The reverse was true for programs with a long laun

span like Pioneer and Mariner.

In terms of influence on the growth and technical development of the network, th

Mariner program exceeded all of the other programs in both complexity and laun

span. It did not produce the longest duration missions, however. The Pioneer progra

would still have viable missions in flight long after the last Mariner mission ended 

1974. Nevertheless, the Mariner program drove the early development of new capab

32

Uplink-Downlink: A History of the Deep Space Networ
ity for the DSIF to a greater extent than any other program and, at a time before th

public and scientific palate had become jaded with a surfeit of “solar system science

it produced many of NASA’s most spectacular scientific results. For that reason, th

period of DSIF history that began with the disastrous launch of the first Ranger in 196

and ended with the hugely successful Mariner 10 spacecraft in orbit around Mercu

and Venus in 1974, is identified here as the “Mariner Era.” 

Of the five projects included in the Mariner Era mission set, three, the Ranger, Marin

and Surveyor projects, were fully managed by JPL. The Ames Research Center in Mounta

View, California, directed the Pioneer Program, while Lunar Orbiter was directed by th

Langley Research Center in Hampton, Virginia.

DSN participation in the Apollo program was directed by the Goddard Space Flig

Center, Greenbelt, Maryland. Because these later projects were not controlled by JP

the different management styles and demands for new standards of performance th

they brought to the DSIF led to far-reaching changes in the DSIF arrangements f

supporting non-JPL or “outside” flight projects. It was the sum total of these ofte

conflicting influences that shaped the character and capability of DSIF during th

Mariner Era. 

In a real sense, the DSIF began its effective operational life as a complete operation

network with the Ranger program, an ambitious JPL mission to land a spacecraft o

the surface of the Moon, in August 1961. 

The Ranger Lunar Missions1

While one stream of activity in JPL had, over the past several years, been focused o

the problems associated with approving, designing, and implementing the DSIF, th

principal effort had been devoted to developing the first spacecraft specifically design

to reach the surface of the Moon. Designated the Ranger Program, this project ha

been assigned to JPL by NASA in December 1959 and was to be completed with

36 months. 

The Ranger spacecraft were much more complex than the earlier Pioneer-type probe

In particular, the Rangers were to be attitude stabilized to keep their high-gain rad

antennas pointed toward Earth and the three antennas of the DSIF. This also allow

the solar panels, which provided power for the spacecraft electronics, to remain poin

ed at the Sun during flight.

3

The Mariner Era: 1961–1974
The battery powered Pioneers had been simply spun like an artillery shell to mainta

their spatial orientation during flight. In addition to attitude stabilization and mo

advanced radio communication systems, some of the spacecraft would carry an ejectab

capsule. This capsule would descend to the lunar surface on a small retrorocket an

thereafter right itself to transmit data on local radio activity and moonquakes. Lat

models were to carry high definition video systems to return detailed pictures of th

lunar surface prior to impact.

The original Ranger program comprised five spacecraft, the first two of which were 

be test flights ejected into an elliptical orbit around Earth. These would be essential

engineering flights to check out the new capabilities of attitude stabilization and sol

power for the spacecraft and, for the DSIF, the all important telecommunication desig

The remaining three spacecraft would consist of a basic spacecraft “bus” with an ejectab

capsule containing a science instrument package and the retrorocket to set it on th

lunar surface. During the flight to the Moon, these spacecraft were to make fields an

particle science measurements and, during the final moments of approach before impac

take close-up vidicon pictures of the lunar surface.

In retrospect, this appeared to be an ambitious plan indeed for a fledgling technolog

as later events proved. However, at the time, it was perceived as the appropriate maj

step forward that was needed to reestablish the prestige and forefront position of America

scientific endeavor, so adversely affected by the Russian success with Sputnik and Lun

some years previously.

Although all five of the first Ranger flights were unsuccessful due to launch vehicle an

spacecraft system failures, the excellent performance of the DSIF proved that the worl

wide network concept of tracking stations managed and controlled from a central locatio

was not only feasible but would be an essential element of future space missions to oth

planets and the Moon.

The Ranger flights demonstrated the value of continuous communication betwee

the spacecraft and the network stations. This provided the Mission Operation team

back in the Flight Operations Control Center with immediate information abo

the status and condition of spacecraft and operating systems during the entire fligh

This included engineering and scientific data. Ironically, this capability allowed th

spacecraft controllers to estimate the reason for all of the Ranger failures attribute

to the spacecraft.

34

Uplink-Downlink: A History of the Deep Space Networ
Following a soul-searching evaluation of the causes of failure of the first five Rang

missions, and some consequent reorganization of technical responsibilities at JP

the program resumed in January 1964. The Ranger team redefined its objectives 

the sole task of securing close-up television pictures of the lunar surface, ostensib

to aid in the design of two more sophisticated lunar missions then under study b

NASA, namely the unpiloted Surveyor landers and the piloted Apollo program

Although the instrumented science capsule had been removed, the mission remaine

very ambitious for those days, as it included a launch into Earth-parking orbit fo

lowed by a second burn of the launch vehicle to transfer the spacecraft into a lun

trajectory. Attitude control maneuvers then followed to orient the solar panels 

the Sun and the spacecraft antenna toward Earth. Further midcourse and termin

maneuvers were required to be correctly executed before the Ranger vidicon drive

cameras could view the lunar surface for the brief period before final impact. Durin

that time, the precious video data would be transmitted to the DSN stations whe

it would be processed and delivered to the Ranger team in the Operations Contr

Center at JPL.

With the reputation of JPL on the line, the first of the final group of four Rangers w

launched in January 1964. Despite the political pressure to demonstrate success after th

poor results from the first group of five launches, Ranger 6 was also a failure. It pe

formed perfectly until the last 10 minutes before lunar impact, at which point th

spacecraft television system should have turned on to start transmitting pictures to th

Goldstone station. There was no indication that this happened, and no pictures we

sent. The cause of this failure was attributed to high voltage “corona discharge” in th

camera’s electrical insulation and appropriate changes were made to the TV subsyste

on the remaining three spacecraft.

Six months later, the fortunes of the Ranger program changed dramatically. Ranger 

launched in July 1964, was a resounding success and radioed 4,300 high-resolution pi

tures of the lunar surface back to Earth. Immediately after lunar impact terminated th

flight, President Johnson called JPL and told Director William Pickering that Ranger 

was “a magnificent achievement.” On behalf of the whole country he congratulat

NASA, JPL, and NASA contractors, saying, “This is a basic step forward in our orde

ly program to assemble the scientific knowledge necessary for man’s trip to the Moon

News conferences and presentations at the White House followed as soon as the film

arrived at JPL from Goldstone and could be processed. The mood at NASA was el

tion, the Ranger team at JPL was ecstatic.

3

The Mariner Era: 1961–1974
The final flights of the Ranger program in February and March 1965 added to the su

cess of Ranger 7. Thousands more pictures of the lunar surface were returned by missio

8 and 9, and the reputation of JPL as a leader in the field of space exploration w

established to worldwide acclaim.

No less delighted than those who were directly involved in the mission was the lun

science community, which, for the first time, had over 17,000 close-up pictures of th

lunar surface for study and analysis. In addition, engineers and scientists designing th

Surveyor and Apollo missions, soon to follow Ranger to the Moon, had a greatly improv

basis for their designs.

In his History of Ranger project, Cargill Hall wrote, “No longer a liability, the Rang

program had vindicated American space policies and presaged accomplishments yet 

come.” It had indeed, and they would not be long in coming.

Mariner Planetary Missions2

Important as it was, Ranger was not the only program demanding the attention of th

DSIF in 1962. By midyear, the first Mariner spacecraft, designed by JPL for planeta

missions as distinct from lunar missions, were on their way to the launch pads at Cap

Canaveral, Florida (later renamed Cape Kennedy). 

Unlike lunar missions, planetary missions have only a very limited opportunity for launc

or “launch window,” which occurs every few years. For missions to Venus, 1962 w

one such year, and the next opportunity for launch would not occur until 1964. NAS

and JPL could not wait that long for a first planetary mission. The attempt to send 

spacecraft to Venus would have to be made in 1962. 

Since the time between the NASA go-ahead and the opening of the Venus launch wi

dow was less than a year, much of the Ranger technology, including the radio subsystem

was utilized for the Mariner spacecraft. For the DSIF, this meant a continuation of th

L-band uplink and downlink support and the possibility of competition with Rang

for the attention of DSIF tracking stations when both Ranger and Mariner spacecra

would be in view at the same time.

This situation, which first appeared in the Ranger/Mariner Era, was to become of immen

importance in the years ahead as the number of flight missions increased. Conflicts f

use of the DSN antennas when view periods of different spacecraft overlapped were 

36

Uplink-Downlink: A History of the Deep Space Networ
frequent occurrence. In the onrush of preparing the Mariners for launch the proble

was deferred.

In addition to the existing 26-meter stations at Goldstone, Woomera, and Johannesbur

the DSN had, at the time of the first Mariner launches, grown to include a Laun

Station at Cape Canaveral identified as DSIF 0, and a Mobile Tracking Station (DS

1), which was located near the Johannesburg station in South Africa. 

It was the purpose of DSIF 0 to track the spacecraft as it lifted off the launch pad ato

the launch vehicle, by manually pointing a small two-meter diameter dish antenna 

the rapidly disappearing launch vehicle/spacecraft combination. This was not a job f

the fainthearted, since the distance between the tracking antenna and the launch p

was necessarily short to ensure that the spacecraft signal was received continuously f

as long as possible after liftoff. This period, seldom more than a minute or two, pr

vided vital engineering information for the DSN regarding the status of the downlin

as the spacecraft started its long journey around the world to reappear over South Afri

at the next tracking station, DSIF 5.

There, the small 3-meter antenna of the Mobile Tracking Station rapidly acquired th

spacecraft and used its pointing information to direct the large 26-meter antenna to th

spacecraft. Once acquired, the spacecraft downlink was tracked and the data it carri

was processed, recorded, and returned to JPL by airmail, a process which at that tim

could, and usually did, take seven days.

Mariner 1962

The first two Mariner spacecraft were essentially long-range versions of the Ranger spac

craft. They carried instruments to make scientific measurements in interplanetary spa

while moving along its trajectory between Earth and Venus. On arrival, they wou

measure the radiation and magnetic fields while the microwave and infrared radiom

ters analyzed Venus’ atmosphere. The spacecraft used the same type of radio syste

(L-band) as had been carried by the Ranger spacecraft.

Two complicated, inflight operations were to be carried out after launch. The first 

these was the midcourse maneuver to correct the trajectory to aim it more precise

at Venus. The second maneuver would point the science instruments to scan the Ven

surface as the spacecraft flew by. The commands to carry out the maneuvers wou

be sent from the tracking stations. The science data would be transmitted by the spac

craft’s three-watt transmitter to the DSN antennas, by then 58 million kilometers fro

3

The Mariner Era: 1961–1974
the spacecraft. Data would “trickle” across those millions of miles of interplaneta

space at just over eight data bits per second. Apart from the tremendous scientif

value of the science data itself, this was regarded as a major technological achieveme

at that time.

Mariner 1 was launched in July 1962, but was destroyed by the Range Safety when 

ran off course shortly after liftoff. However, Mariner 2 injected into a Venus trajecto

by an Atlas-Agena launch vehicle the following month, performed exactly as intende

Following a perfect liftoff, DSIF 0 followed the spacecraft until it disappeared over th

horizon. The spacecraft appeared over South Africa some 28 minutes later and w

acquired by DSIF 1 with no problem. Within three minutes, the big, 26-met

Johannesburg antenna had found the spacecraft and began receiving engineering data 

verify the spacecraft had survived the stresses of the launch environment.

The midcourse maneuver was carried out successfully and, after some further commandin

to correct a temperature problem, reached Venus in mid-December. After passing Ven

at a range of 40,000 miles, the spacecraft continued in orbit around the Sun until 

fell silent on 2 January 1963. The DSN stations searched the empty airwaves for se

eral days trying to find some sign of life from the first planetary spacecraft but non

was found. In its brief lifetime, Mariner had transmitted 11 million data bits of scien

and engineering data back to Earth.

As a consequence of experience with the first Ranger and Mariner missions, the DS

began work to improve its capability so that engineering and science data could 

relayed back to JPL as it was received from the spacecraft, that is to say in real tim

Automatic monitoring of the DSIF stations would be added to permit the engineerin

experts at JPL who had designed the station equipment originally to aid the remote st

tion staff in troubleshooting and problem identification. Even greater emphasis was 

be placed on good engineering practices, conservative design, and thorough testing 

minimize equipment failures in the field. Techniques to acquire the spacecraft downlin

as early in flight as possible were studied. Small wide-beam antennas for “initial acqu

sition” were added to the network antennas and the accuracy of flight path predictio

was improved.

The experience gained from these early flights also led to a new approach to DS

telecommunications link design, in terms of receiver sensitivity and transmission pow

of the ground tracking station. Combined with similar considerations for the spacecra

radio system, the basic concepts of uplink and downlink performance became firm

38

Uplink-Downlink: A History of the Deep Space Networ
established as the methodology for all future deep space communications engineerin

design.

Mariner 1964

A “launch window” for Mars only opens every 25 months, and such an opportuni

occurred in late November 1964. To take advantage of this situation, NASA chose 

Mars-1964 project based on JPL’s experience with the earlier Venus missions. Thr

spacecraft were to be built, two for flight, with one as backup that operated at the the

new S-band frequency.

The Mariner 3 and Mariner 4 missions were to be supported with the existing DS

26-m stations at Goldstone, Johannesburg, and Woomera, plus a new station in Austra

which had been built at Tidbinbilla near Canberra. The stations at Woomera an

Johannesburg that retained the old L-band receiving equipment were fitted with co

version equipment, which enabled them to receive the S-band signals from the Marin

spacecraft. In addition, the R&D station at the Goldstone Venus site, which by the

had acquired a high-power, 100-kW transmitter, was to provide backup for the 10-kW

transmitters at the other stations in the event spacecraft problems required a more pow

erful uplink for commanding purposes.

These first Mars flights also coincided with very significant improvements in the cap

bility and operational management structure of the Ground Communications Facili

(GCF) and Space Flight Operations Facility (SFOF) at JPL. The SFOF was a large dat

handling machine, albeit housed in a barely finished new building at JPL, where da

arriving from the tracking stations was processed in real time and distributed to th

DSN and Flight Project Operations Control Groups for action and to Science Grou

for analysis. The simple control room of the Ranger and early Pioneer days with a fe

desks, teletype machines, and display boards was “history.”

Although the first of the Mariner 1964 missions failed due to a launch vehicle pro

lem, the second, Mariner 4, was launched successfully on 8 November 1964. A litt

more than seven months later, it reached Mars. On 14 July 1965, in response to com

mands from the Johannesburg tracking station, the Mariner 4 spacecraft turned on 

cameras, tape recorders, and scientific instruments in preparation for the first close-u

look at Mars. As the encounter point approached, the Mariner 4 cameras focused o

Mars and took a 25-minute sequence of pictures of the Martian surface before the spac

craft trajectory took it behind the planet. The pictures were stored on the spacecra

3

The Mariner Era: 1961–1974
tape recorder. Playback to Earth began when the spacecraft came into view of the trac

ing stations, about an hour later.

It must be pointed out here that although the many millions of data bits in the pi

ture images could be recorded almost instantly by the spacecraft, it would take man

days to return the recorded data back to Earth, due to the limited capability of th

downlink. The first pictures of Mars took ten days to playback. This would chan

radically in the years ahead, but at the time of Mariner 4, the downlink capabili

between Mars and Earth for the 26-m antennas of the DSIF was limited to on

8.33 bits per second.

40

Uplink-Downlink: A History of the Deep Space Networ

Figure 2-3. First close-up picture of Mars. Returned from Mariner 4 on 14 July 1965. The ph

tograph shows the Phelgra region and Mars horizon from a distance of approximately 10,500 mile
After a second playback of images and science data, Mariner 4 continued along its orb

around the Sun, sending back more science and engineering data until the downlin

was inadvertently “lost” about two and a half months later.

Scientifically, the mission was judged to be a great success, affording humankind th

first close-up views of the Martian surface. Crude as they appear now, those first image

transmitted laboriously at about 8 bits per second over millions of miles of deep spac

were hailed with tremendous enthusiasm by the public at large. A composite image 

the Phelgra region of Mars, taken by the Mariner 4 spacecraft, was proudly display

in the Main Lobby of the Engineering Building at JPL, where for many years, it serv

both as a reminder of the humble beginnings of the planetary program and as the poi

from which to gauge the astonishing progress that would take place over the next fe

years. The original picture is reproduced in Figure 2-3.

For some time after the downlink signal was lost by the DSIF stations, the R&D Ven

station at Goldstone continued to search for it. Eventually the signal was recovered an

used to check out and calibrate the new 64-meter antenna at Goldstone. It was al

planned to use Mariner 4 in conjunction with Mariner 5 to perform radio science expe

iments in interplanetary space from three vantage points: two spacecraft and Eart

However, the spacecraft supply of attitude control gas was exhausted during enginee

ing tests in this extended phase of the Mariner 4 mission. After three years of operatio

in space, and 1,119 passes by the DSN tracking stations, the mission was terminated

Mariner 1967

NASA chose to use the 1967 planetary launch window for a second mission to Venu

The spacecraft for this mission would be the one remaining spacecraft from the thr

that had been built for the 1964 Mars missions. Fitted with a different set of scien

instruments, including a photometer, radiometer, and plasma probe, the spacecraft wou

further explore the dense, optically opaque Venusian atmosphere. 

The tracking and data acquisition requirements for support of Mariner 5 were comp

cated by the DSN desire to involve Mariner 4, which had since been recovered, 

simultaneous radio science experiments in interplanetary space. In addition, new telem

try and command processing equipment added to the Network, between the Marin

4 and Mariner 5 launches, further complicated the technical and operational interfac

between the DSN stations and the flight project organization at the SFOF. The spac

craft was more complex, too. It carried, in addition to the standard lunar ranging system

a newly developed system of ranging for its first flight evaluation. The Tau system, 

4

The Mariner Era: 1961–1974
it was called, was designed to extend the DSN ranging capability beyond the limit 

the lunar distance. 

At Goldstone, Mariner 5 would be supported by the two 26-m stations (Echo an

Pioneer) and the new 64-m Mars station. In Australia, it would be Woomera and th

new 26-m station at Tidbinbilla that would be used. Johannesburg and another ne

26-m station at Robledo, near Madrid, Spain, would complete the DSN support f

this mission. At the SFOF, a new 7044 computer system would see its first operation

use on Mariner 5 and demonstrate the capability to process Mariner 4 and Mariner 

data simultaneously, even though the data streams came from different DSN station

To handle so many data streams from the increasing number of tracking stations, 

newly installed communications processor in the SFOF used computer switching 

direct all communications throughout the DSN.

Launched on 14 June, the spacecraft was first placed in an Earth parking orbit befo

being injected into a final trajectory to Venus. Before reaching the limit of its capab

ity, the DSN lunar ranging system followed the spacecraft to a distance of 10 millio

km, making Mariner 5 the first spacecraft to be ranged beyond lunar distance. The ne

Tau ranging system was activated about two weeks before success in tracking the spac

craft to the Venus encounter and beyond, to about 75 million km. Together with Doppl

and angle data, ranging data became a standard type of radiometric data generated b

the DSN and greatly enhanced the orbit determination process for the navigation 

future spacecraft. With the downlink running at 8.33 bits per second and encount

activities proceeding smoothly, Mariner 5 made its closest approach to Venus on 1

October 1967, at a range of 3,946 km. The science return satisfied the mission obje

tives and the DSN continued to track the spacecraft until it passed out of radio ran

at about 160 million km.

Mariner 1969 

In discussing the background to the Mariner 1969 missions Corliss wrote, “Earlier prob

to Venus and Mars had indicated that Mars was the most likely planet in the solar sy

tem to support life. The richly detailed and cratered surface of the planet revealed b

Mariner 4 had surprised planetologists and made them anxious for more photos. Ma

thus became NASA’s prime planetary target. The Mariner Mars 1969 mission, therefor

concentrated on TV imaging of the planet’s surface, and experiments that might aid th

design of future missions, particularly those looking for life. Besides the TV camera

the two new Mariner-type spacecraft assigned to the mission carried an ultraviolet spe

trometer, an infrared spectrometer, and an infrared radiometer.”

42

Uplink-Downlink: A History of the Deep Space Networ
For the DSN, the Mariner 1969 missions were of special importance because they inclu

ed the first flight demonstrations of the new DSN high rate telemetry system. Previous

with downlinks limited to just over 8 bits per second, playback of telemetry data fro

spacecraft at the range of Mars or Venus was measured in days or even weeks. With th

DSN’s new block-coded telemetry system running at 16,200 bits per second, rough

two thousand times faster than the former system, low resolution pictures could be se

in real time from Mars. The new high rate telemetry did not replace the existing lo

rate system. It was an addition to the DSN’s rapidly increasing capability for planeta

exploration. Corliss continued, “The DSN was ready for the much greater distances an

higher rates required (for planetary exploration). The various technical advances and ne

facilities just described had begun years before the new missions left their launch pad

As usual though, the new DSN capabilities, which had seemed perhaps unnecessari

ambitious when proposed, were quickly absorbed by the new mission designers.”

Tracking and data requirements for the Mariner 1969 missions (Mariners 6 and 7

included not only the existing 26-m stations, but the new 64-m antenna at Goldston

as well. The downlink would carry telemetry data at either 8.33 or 33.33 bits per se

ond for normal spacecraft operations during the cruise period. When the spacecra

reached Mars, the new high rate telemetry experiment would be turned on. Of cour

telemetry reception at 16,200 bits per second would be possible only when the spac

craft was in view of Goldstone, where the big 64-m antenna was required to enhan

the downlink sufficiently to carry data at this rate.

Orbit determination requirements for the very precise navigation needed to fly the spac

craft close enough for a Mars encounter would be based on standard radiometric dat

including an improved version of the Tau planetary ranging system.

Both Mariners 6 and 7 were launched successfully in February and March 1969. F

the first time, NASA had successfully launched a pair of spacecraft. Both spacecraft we

on target and, from a DSN viewpoint, both were in the same part of the sky. Th

meant that both spacecraft would be in view of a given DSN site, although not wit

in a single antenna beamwidth, simultaneously. Tracking both spacecraft simultaneous

required two antennas and two telemetry data processors, one for each downlink. At th

same time, there were the Pioneer spacecraft and backup support for the first Apol

missions to be considered as well. The “loading” on the DSN antennas had begun 

reach the point of saturation, and the resource allocation system was hard pressed 

service all of its customers. 

4

The Mariner Era: 1961–1974
As Mars began to draw near towards the end of July, encounter operations began wi

Mariner 7 only five days behind Mariner 6. Corliss describes what happened nex

“All seemed to be going well until about six hours before the Mariner 6 encounte

when Johannesburg reported that the signal from Mariner 7 had disappeared. It w

an emergency that came at the worst possible time. The Robledo, Spain[,] antenn

discontinued its tracking of Pioneer 8 and began to search for the lost spacecraft. Whe

Mars came into view for Goldstone, the Pioneer 26-m antenna joined the searc

while the Echo 26-m antenna continued tracking Mariner 6. It was decided to sen

a command to Mariner 7 to switch from the highly directional high-gain antenna 

its omnidirectional low-gain antenna. The spacecraft responded correctly, and sudden

both the Pioneer station and the Tidbinbilla station began receiving low-rate telem

try from the recovered spacecraft. Something had happened to the spacecraft but n

one knew just what.”

While the DSN was committed to support one Mariner at a time in a mission-critic

phase, this situation presented one spacecraft approaching encounter and a second on

with a serious and unknown problem. To deal with it, the DSN applied its main effo

to the ongoing Mariner 6 encounter, while a special team at JPL studied the Marin

7 anomaly.

Fortunately, the Mariner 6 encounter events executed without any problems. Many pi

tures of Mars were taken and successfully returned to Earth using both the high-ra

and normal low-rate telemetry systems. The special “Tiger Team” at JPL was able 

overcome the Mariner 7 attitude problem by using the real-time high-rate telemet

sight, the TV cameras on Mars, in time to carry out a very successful encounter.

For both encounters, the new High-Rate Telemetry System (HRT) proved its wort

not only in recovering from the Mariner 7 emergency, but also in providing a mu

faster channel for playing back TV and other high-rate science from Mars to Earth. 

all, 202 pictures covering almost 20 times the area covered by Mariner 4 were return

to Earth by the Mariner 6 and 7 missions.

Following the formal end of the mission in November 1969, both spacecraft, still ope

ating perfectly, were used to perform radio science experiments in relativity, astronomic

constants, and electron densities in interplanetary space.

44

Uplink-Downlink: A History of the Deep Space Networ
Mariner 1971

We turn again to Corliss for a view of these missions: “The logical follow-on missio

to Mariner-Mars 1969, using the lunar program analogy, would be picture-taking orbite

around Mars. The next Mars opportunity was in the spring of 1971, and two Marine

class spacecraft were prepared accordingly. The new Mariners drew heavily upon th

technology of the 1969 mission. Instrumentation was very similar, with emphasis aga

on photography. The primary objectives were the search for evidence of life and th

gathering of data that would aid Mars landers. After mapping as much of the surfa

as possible, scientists wanted more data on the density and composition of the Martia

atmosphere. A 90-day orbital mission for each spacecraft was planned. These spacecra

would be the first terrestrial satellites of another planet.”

The requirements levied upon the DSN for these missions were even more extensi

than those of the 1969 missions. This was due to the precise navigation and maneuve

needed to inject the spacecraft into orbit around Mars and to the DSN antenna cove

age required for 90 days of orbital operations for two spacecraft simultaneously.

During the intervening two years between the Mars opportunities, DSN capabiliti

expanded considerably. The Multimission Telemetry System had been inaugurated o

the 1969 flights, and for the 1971 mission. The experimental HRT, which had bee

demonstrated so successfully in 1969, was fully operational. Pictures and science cou

be transmitted back from Mars to Goldstone much more rapidly. A 50,000 bit per se

ond wideband communications link was available to carry two 16,200 bits per secon

(16.2 kbps) data streams simultaneously between Goldstone and JPL. In effect, the DS

now had a downlink capable of delivering two simultaneous 16.2 kbps data stream

directly from Mars to JPL in real time. Of course the Mars station at Goldstone w

the only 64-m antenna in operation at that time, but the high speed readouts of th

Mariner 71 tape recorders were planned to take place only when DSS 14 had Mars 

its view. Another important capability of the DSN, which was planned for use on the

missions, was the ability of a single DSN antenna to simultaneously handle two spac

craft located in the same beamwidth.

The Mariner 71 flights began inauspiciously with a failure of the upper stage (Centau

of the Atlas-Centaur launch vehicle which resulted in the loss of Mariner 

Investigation of the Centaur problem delayed the next launch to 30 May whe

Mariner 9 lifted off on a direct ascent trajectory for Mars with an arrival in mi

November 1971. Although the loss of one spacecraft placed the burden 

4

The Mariner Era: 1961–1974
responsibility for the entire mission on Mariner 9, it reduced the burden of trac

ing for the DSN to a single spacecraft.

After a perfect midcourse maneuver in June and a nominal cruise to the planet, Marin

9 was injected into Mars orbit on 14 November. Unfortunately, just at the time 

Mariner 9’s arrival, the planet was covered by a huge dust storm, which precluded an

useful photography. Mariner 9 continued to make its regular 12.567 hour orbits wh

the scientists waited for the dust to settle. While the spacecraft waited in orbit, the oth

instruments were busy and pictures of Mars’s moons Phobos and Deimos were taken

By 3 January 1972, the dust storm had cleared sufficiently for the 90-day mission 

begin. Soon, the pictures came by the thousands to reveal, for the first time, deep fl

vial channels, possibly cut by water, and evidence of ice action in the polar region

Detailed maps of the Martian surface, needed to plan the Viking landings to come 

few years later, were being drawn even as the Mariner 9 cameras covered more and mo

of the surface of the planet.

Because the spacecraft was still operating so well at its nominal end date in April, NAS

extended the mission to re-examine some specially interesting areas and observe sol

occultations as the spacecraft moved through the shadow of Mars twice per day. Despi

its rigorous and longer than planned mission, Mariner 9 survived until 27 October 197

Mariner 1973

The launching of Mariner 10 in November 1973, on the first mission to Venus an

Mercury, marked the end of the Mariner spacecraft era. Immensely successful as it wa

the Mariner 1973 Venus-Mercury mission was the last to use the so-called Mark III-7

network model which had supported the previous Mariner missions to Mars in 196

and 1971 and the later Pioneer missions to Jupiter.

High-rate telemetry, wideband communication circuits connecting all complexes to JP

and 64-m antennas at all three sites formed the basis for the DSN support of the Marin

10 mission. However, the spacecraft carried a redesigned imaging system that requir

the DSN to provide a downlink capability from Mercury of 117.6 kbps to fully explo

the new imaging system capability. This data rate greatly exceeded the operational cap

bility of the existing DSN high rate telemetry system of 16 kbps.

Responding to pressure from the Project, the DSN had proposed a substantial numb

of improvements to the existing DSN downlink capability to increase the mission da

46

Uplink-Downlink: A History of the Deep Space Networ
return and enhance its science value. These improvements included 1) the installatio

of a developmental supercooled maser and ultra cone at DSS 43; 2) the installation 

an S/X-band dichroic plate and feed cones at DSS 14; 3) the implementation of a sp

cial 230-kbps wideband data transmission circuit from Goldstone to JPL for real-tim

picture transmission and a 28.5-kbps circuit from Australia and Spain to JPL for tran

mission of recorded data; 4) the redesign of the telemetry and command processor (TC

computer software to handle the data rates as high as 117 kbps; and 5) the installatio

of a Block IV receiver-exciter at DSS 14 for the S/X-band Radio Science Experimen

As the mission extended into a second encounter with Mercury in 1974, the increasin

Earth-spacecraft range introduced further losses into the telecommunication path. T

compensate for this additional loss, the DSN implemented a new signal enhanceme

technique, previously developed and demonstrated by Spanish engineers at the Madr

Complex in 1969 and 1970. In this technique, the spacecraft signals from several DS

stations were added together at a central point so that their combined signal streng

would be greater than that of a single station. The new “antenna arraying and sign

combining” technique was implemented, this time at Goldstone, using stations DS

14, DSS 12, and DSS 13. Tests with the spacecraft demonstrated an improvement 

downlink performance of 0.7 dB. In September 1974, the new technique was used f

the first time by the DSN, with good results, as a fully operational capability to su

port the second Mariner 10 Encounter of Mercury. 

The Mariner 10 data return statistics were impressive. At its conclusion, it had return

to Earth over 12,000 images of the planets Venus and Mercury. In terms of scienti

cally useful pictures, this exceeded the combined total of the Mariner 6 and 7 missio

to Mars by a factor of almost 15.

The time Mariner 10 had spent in deep space, short though it was, had been very even

ful. Years later, Bruce Murray, who at the time was leader of the Mariner 10 Imagin

Team, expressed his view of the scientific worth of the mission, “The economy cla

Mariner flyby of Venus and Mercury was one of the most productive space science expe

iments ever carried out.”3

On 24 March 1975, shortly after its third flyby of the planet Mercury and exactly 50

days after its launch in November 1973, the last of the Mariner series of planetary spac

craft fell silent. With its attitude control gas supply exhausted, Mariner 10 started 

slowly tumble out of control, and controllers at the Jet Propulsion Laboratory in Pasaden

California, sent a command to turn off its transmitter to avoid contaminating the de

space environment with an unwanted source of radio emissions.

4

The Mariner Era: 1961–1974
From the DSN point of view, the Mariner 10 Mission to Venus and Mercury was ass

ciated with a long list of “firsts.”

The Mariner 10 mission was the

• first multiplanet gravity assist mission,

• first spacecraft to photograph Venus,

• first spacecraft to fly by and photograph Mercury,

• first spacecraft to have multiple encounters with a target planet,

• first JPL spacecraft to transmit full-resolution pictures in real time from planetary d

tances,

• first mission to use dual-frequency radio transmission, and 

• first mission to use arrayed ground station antennas to improve signal-to-noise rati

For the DSN, the Mariner 10 mission to Venus-Mercury provided a fitting conclusio

to the Mariner Era. During that era, there had been many other important missio

sharing the attention of the DSN, which will be discussed later. Nevertheless, it was th

Mariners that influenced the future capabilities of the DSN for the longest time and 

the most significant way, as is evident in the summary of the Mariner missions co

tained in the following table (on the following page). 

Pioneer Interplanetary Missions4

Unlike the short missions of the five earlier Pioneer lunar probes, the second gener

tion of Pioneer spacecraft consisted of long duration missions designed to measure th

interplanetary fields and particles environment along trajectories that placed the spac

craft in heliocentric orbits ranging between 0.7 and 1.2 AU. They were sometim

described as interplanetary weather stations. The four spacecraft, Pioneers 6–9, were ea

launched approximately one year apart, starting in December 1965 with Pioneer 6 an

ending in November 1968 with Pioneer 9.

All four spacecraft transmitted continuous streams of scientific data from vario

orbits around the Sun. This meant that the DSIF was required to provide almo

continuous tracking for first one, and eventually four Pioneers, to ensure that all 

the rapidly changing science data were captured. Furthermore, instead of dying aft

the first year or so of operation as was expected, all four Pioneers continued to ope

ate actively in deep space for many years. At the end of the Mariner Era they we

still going strong and had become a permanent feature of the DSIF routine trac

ing schedules.

48

Uplink-Downlink: A History of the Deep Space Networ
Summary of the Mariner Planetary Missions: 1962–73

Mission; Objective Science Max. Data Rate

Launch Date Result Return at Encounter

1, Venus; Flyby, None None

Jul 62 Failure

2, Venus; Flyby, Scanned Venus surface 8.33 bits/sec

Aug 62 Success at encounter

3, Mars; Flyby, None None

Nov 64 Failure

4, Mars; Flyby, First close-up photos 8.33 bits/sec

Nov 64 Success of Mars surface

5, Venus; Flyby, Science data on Venus 16.33 or 8.33 bits/sec

Jun 67 Success surface environment

6, Mars; Flyby, High-res. photos of Mars’ 16,200 bits/sec

Feb 69 Success equatorial region

7, Mars; Flyby, High-res. photos of Mars 16,200 bits/sec

Mar 69 Success southern hemisphere

8, Mars; Orbiter, None None

May 71 Failure

9, Mars; Orbiter, Mapped whole Mars surface 16,200 bits/sec

May 71 Success photos and data from Mercury

10, Venus/ Flyby, UV photos of Venus, 117,600 bits/sec

Mercury; Orbiter, close-up photos and

Nov 73 Success data from Mercury

The new Pioneer program was directed by the NASA Ames Research Center (ARC) 

Mountain View, California, and thus it became the first major non-JPL or “off-La

flight project to require support from the DSIF. In addition, ARC wanted to exerci

mission control functions from Mountain View rather than from the mission contr

center at JPL in Pasadena. These and other requirements, related to enhanced downlin

capability, presented a new situation for the DSN and forced it into broadening its ma

agement structure to deal with flight projects other than those directed by JPL. In d

course, special positions were created in the DSN Office to deal with the unique requir

ments of each new flight project. This unique position was given the title of “DS

Manager for Project . . . .”

4

The Mariner Era: 1961–1974
Like other flight projects in these early years, the Pioneer Project provided the trac

ing stations with a set of unique Ground Operational Equipment (GOE) for u

when the station was tracking its particular spacecraft. The stations were obliged 

take on the onerous tasks of accommodation, installation, maintenance and oper

tion. The GOE provided real-time telemetry data processing and spacecra

commanding functions, which could not be handled by the existing DSIF equi

ment because the Pioneer spacecraft design differed from that of the current JP

spacecraft. Eventually, the Madrid engineering staff developed new software for th

DSN’s Multiple Mission Telemetry and Command Processor that emulated the GO

functions and interface signals, thereby avoiding the need for the special Pionee

unique equipment in the Network.

For the most part, the DSIF used the network’s 26-m antennas to support the Pione

missions. However, as the Pioneers reached the threshold of detection capability for th

26-m antennas, improvements in downlink sensitivity became necessary to the conti

ued life of the missions. DSN engineers made systematic improvements in the S-ban

maser sensitivity, microwave equipment, and receiver “tracking loop” performance an

advanced demodulation hardware, while Madrid engineering staff developed special co

volutional decoding software for Pioneer 9. As a result of these improvements, the thresho

of performance for Pioneer on the 26-m antennas was extended from 0.4 AU in 196

to 1.5 AU by 1969. Although it was driven by the enduring performance of the Pionee

the improved downlink capability was, of course, of great benefit to later missions an

the to the DSN in general.

Inevitably, as the Pioneers moved steadily deeper into space, the strength of their dow

link signals dropped below the detection capability of the enhanced 26-m antenna

Now, fully compatible with the Network’s multiple mission capabilities, the Pione

spacecraft were transferred to the new 64-m antennas which were, fortuitously, just com

ing into service in the network. With the great increase in downlink capability that th

64-m antennas brought to the Network, the communication range of the Pioneers w

extended significantly into, and even beyond, the next era.

Pioneer Jupiter Missions

Much smaller than the JPL-designed Mariner-class spacecraft, the interplaneta

Pioneers were simple and rugged and, being spin-stabilized, avoided the complexiti

of three-axis attitude control used by the Mariners. The efficacy of their design ha

been amply demonstrated by four years of continuous deep space operation when, 

1969, NASA selected the “third generation” Pioneers for the first missions to Jupite

50

Uplink-Downlink: A History of the Deep Space Networ
Although the Jupiter Pioneers were technically more advanced than the previous spac

craft, the design philosophy was much the same. This project was directed as befor

by ARC. 

The spacecraft were instrumented to carry out fields and particles measurements throug

out the entire mission. At Jupiter they were to explore the Jovian system, obtain th

first spin scan images of the planet, and investigate its enormous magnetosphere. To te

new technologies for future missions into this previously unexplored region of deep spac

where sunlight was too weak for satisfactory operation of solar cells, the spacecraft we

powered by Radioisotope Thermal Generators (RTGs). Instead of a mast-type of ante

na, the new Pioneers carried 2.75-m parabolic dish antenna for communications wi

the DSN. They were, for their time, very advanced spacecraft.

Pioneer 10 finally left the launch pad on 3 March 1972, and made its closest approac

to Jupiter 21 months later, on 4 December 1973, at a distance equal to 2.86 Jupit

radii, 302,250 km from the center of the planet. Science data from the encount

instruments confirmed the complexity of the Jupiter system. For the first time, clos

up photos of the planet surface were obtained and an atmosphere was detected on th

satellite Io. The giant planet’s magnetosphere was found to be disk shaped and bigg

than the Sun itself.

DSN support for the Pioneer 10 Jupiter mission was complicated by serious conflic

for the 26-m and 64-m antennas by the Mariner 10 mission to Mercury and Venus an

by the need for Goldstone 64-m radar surveillance of possible Viking-Mars landing site

The multiplicity and complex nature of these overlapping view periods presented th

DSN with a problem it had not encountered up to this time, but which loomed om

nously in the years ahead. A Network Allocation Working Group was established 

resolve the conflicts by mutual compromise between the conflicted projects. The DS

had moved from an age when it could assign antennas for the exclusive use of a sing

flight project to an age when it would be necessary to assign missions to antennas o

a day to day, or even hour to hour, basis. Thus was born the DSN scheduling system

which soon became a permanent feature of daily DSN activity.

By the close of the Mariner Era, eleven DSN stations had provided 2000 tracking pas

es for Pioneer 10 between April 1972 and January 1974, the equivalent of 21,000 hou

of tracking time. During this time the spacecraft distance from Earth varied from 2

million to 890 million kilometers. During the 60-day Jupiter encounter period, ov

17,000 commands were sent to control the complex spacecraft sequences.

5

The Mariner Era: 1961–1974
Except for a sling-shot (later called a gravity-assist) encounter with Jupiter, the Pione

11 mission was essentially the same as that of Pioneer 10. It was launched on 6 Ap

1973 and reached Jupiter at the end of the year. 

Building on the success of the Pioneer 10 encounter with Jupiter, the ARC mission co

trollers retargeted Pioneer 11 in flight in such a way that, at its encounter with Jupit

in December 1973, trajectory was altered to eventually intercept the ringed planet Satur

Pioneer 11 went on to pass within 20,000 kilometers of Saturn’s main outer ring sy

tem on 1 September 1979, and became the first spacecraft to do so. The remarkab

success of Pioneer 11, discussed further in the chapter on the Voyager Era, paved th

way for the Voyager spacecraft to later pass Saturn. 

Surveyor Lunar Lander Missions5

Originally the objectives of the Surveyor Lunar Lander program, complemented by Lun

Orbiters, were primarily scientific in nature. After Apollo became a national goal, th

objectives of the Surveyor program were redirected somewhat towards determining wheth

a human could land safely on the surface of the Moon. The Surveyor program was ma

aged by JPL and controlled from the Space Flight Operations Facility (SFOF) whi

had replaced the simple mission control center of the early days. 

The DSN felt the impact of Surveyor in a number of ways. These stemmed from a ne

(to the DSN) concept that Surveyor planned to use to control its spacecraft once th

landed. The spacecraft had few automatic features and depended almost entirely on rea

time commands for its operation on the lunar surface. This concept of interactive contr

of a distant spacecraft was based on real-time video and other data displays of the cu

rent state of the spacecraft. These data would be used by spacecraft controllers to ma

decisions regarding the desired future state of the spacecraft. Commands transmitt

from the DSN stations would control the actions of the spacecraft accordingly. To ma

this possible, video data streams from the tracking stations, 4,400 bits per second fro

Goldstone, 1,100 bps from the overseas stations, were first transmitted via the Groun

Communications circuits to the SFOF. There the data was converted to television d

plays for operational decisions by the spacecraft controllers, and to photographic imag

for scientific interpretation by the project scientists. 

Obviously this level of operational decision making was completely dependent upon th

reliability of the communications circuits between the DSN sites and JPL. To ensu

the integrity of the overseas communication circuits for Surveyor, all DSN traffic wa

for the first time, carried on a high-quality satellite channel provided by NASCOM.

52

Uplink-Downlink: A History of the Deep Space Networ
As was the case for Pioneer, the Surveyor Project provided special mission-depende

equipment in the form of a Command and Data Console (CDC), for installation 

each of the DSN stations, that would support the missions. The CDCs were operat

and maintained by project people who were resident at the stations, pending the tran

fer of responsibility to the DSN. In the event of a loss of communications between 

DSN station and mission control at the SFOF, these personnel would be capable 

controlling the spacecraft to ensure its safety until the situation was corrected.

In the period prior to launch of the first Surveyor, lengthy and elaborate simulatio

were carried out to prepare the DSN and Surveyor operations teams for the scenari

they would likely face in interacting with the spacecraft on the lunar surface. 

Using its new Atlas-Centaur launch vehicle, NASA launched seven Surveyors betwee

May 1966 and January 1968. The success of all seven launches demonstrated the re

ability of the new high-energy Centaur upper stage, a potent liquid-hydrogen-fuell

booster rocket which had recently been developed at NASA’s Lewis Research Cent

The Centaur subsequently came into general use as an upper stage for deep space m

sion launches, until the program was discontinued in 1986 as a consequence of th

Space Shuttle Challenger disaster. 

Landing sites for the Surveyor spacecraft had been chosen primarily for their interest 

the future Apollo program and four of the spacecraft soft-landed successfully at, or ne

these sites and returned large quantities of engineering and scientific data. Two of th

spacecraft failed to reach the lunar surface. Surveyor 7, the final spacecraft of the serie

was targeted to land in the more scientifically interesting lunar highlands. After a su

cessful landing it demonstrated the advantages of real-time control and manipulato

capability by carrying out a number of experiments that involved digging trenches, mo

ing rocks, and even recovering an alpha-scattering experiment that had failed to depl

correctly after touchdown. The effort that went into the pre-launch simulation effor

clearly proved to be worthwhile.

Despite the complexity of the Surveyor program, DSN support for all seven flights w

deemed to be excellent due in no small measure to the exhaustive testing and trainin

program that preceded the first launch. The table below, which summarizes the da

returned from each of the Surveyor missions, attests to the quality of the DSN da

retrieval support. 

5

The Mariner Era: 1961–1974
Summary of Surveyor Lunar Lander Missions

Mission; Launched Spacecraft Operations on the Lunar Surface

1; 1966; 30 Mar Soft landing, operated for 2 lunar days. Returned 13,000 pictures,

received 108 commands.

2; 1966; 20 Sep Spacecraft became unstable, destroyed itself in flight.

3; 1967; 17 Apr Soft landing, operated for 1 lunar day. Returned 10,000 pictures,

received 63,000 commands.

4; 1967; 14 Jul Lost radio contact touchdown.

5; 1967; 11 Sep Soft landing, operated for 2 lunar days, 118 hours of alphascatter experiments. Returned 27,000 pictures, received 123,000

commands.

6; 1967; 7 Nov Soft landing, operated for 1 lunar day, 30 hours of alpha-scatter

experiments. Returned 45,000 pictures, received 170,000 commands.

7; 1968; 7 Jan Soft landing, operated for 1 lunar day, 100 hours of alphascatter, many surface sampler experiments. Returned 28,000 pictures, received 150,000 commands.

Note: One lunar day is equivalent to approximately 27 Earth days.

Lunar Orbiter Missions6

Although an orbital lunar mapping mission had been originally conceived by JPL as a

adjunct to the Surveyor lander program, NASA eventually assigned the development an

management of the Lunar Orbiter project to the Langley Research Center in Hampto

Virginia. 

The main objective of the Lunar Orbiter project was to obtain high-resolution phot

graphs of potential Apollo landing sites on the Moon to complement those made b

Surveyor on the actual surface. From its continuous orbit about the Moon, it wou

also make a detailed photographic survey of the entire lunar surface. To accomplish th

task, the spacecraft carried a complex wide-angle camera and film processing packa

which employed facsimile transmission techniques to return the images to Earth via th

tracking stations of the Deep Space Network. There were five identical spacecraft in th

Lunar Orbiter program, all launched on Atlas-Agena vehicles in one year, beginnin

August 1966. All five missions were successful. Each of the missions orbited the Moo

at a different inclination to the lunar equator and was therefore able to scan a differe

section of the lunar surface. The combined result of all five missions amounted to a su

54

Uplink-Downlink: A History of the Deep Space Networ
vey of almost 99 percent of the entire lunar surface. By the time the project ende

Lunar Orbiter had surveyed the entire front surface of the Moon and most of the ba

surface, in some 2,000 individual high-definition, photographic images. 

A standard S-band network of three deep space tracking stations was used to suppo

the five Lunar Orbiter missions. Like the Pioneer and Surveyor projects, the Lun

Orbiter project provided these stations with special purpose mission-dependent groun

reconstruction equipment (GRE), as well as personnel to operate them. The Lunar Orbit

missions were conducted concurrently with the Surveyor and Mariner-Venus mission

This multiple-mission environment heavily taxed the resources of the DSN and, b

requiring precise scheduling of the activities of all three projects and a high degree 

cooperation and coordination between them, presaged the later establishment of th

Network Resources Allocation Working Group.

The Lunar Orbiter missions provided the DSN with the first opportunity to evalua

its new “turnaround” lunar ranging system in actual flight operations. Prior to this tim

Earth to spacecraft range had been estimated by electronically processing the Doppl

tracking data, a method that was cumbersome and prone to errors from “slipped cycles

The Lunar Orbiter spacecraft carried a ranging transponder, which, after detecting a sp

cial code carried on the uplink, would retransmit the code along with telemetry da

on the downlink back to Earth. At the DSN tracking station, special ranging equi

ment compared the downlink code with uplink code to calculate the time it took th

range code to travel out to the spacecraft and back. After proper calibrations and co

rections were applied, spacecraft navigators used these data to obtain a very precise val

for the spacecraft range (distance between tracking station and spacecraft). So succes

ful were these inflight demonstrations that turnaround ranging, in various more refin

forms, soon came into regular use along with Doppler data as the standard types 

radiometric data generated by the DSN for all lunar spacecraft navigation purposes. 

In addition to refining the new turnaround ranging system, DSN engineers extend

its use to improve the time synchronization between DSN stations throughout the worl

This enabled a more accurate determination of the spacecraft orbit about the Moo

which in turn yielded more and better information about the geophysical properties 

the Moon itself. In addition to purely scientific interest, these data also provided val

able background information for the design of the Apollo piloted missions to the Moo

which were about to begin.

After the Lunar Orbiter program ended, scientists at JPL continued to analyze the weal

of DSN ranging and other radiometric data that had been generated during the Lun

5

The Mariner Era: 1961–1974
Orbiter missions. The outcome of this work greatly improved our understanding of th

radius, orbit, and gravitational field of the Moon. It also led to the discovery of hit

erto unknown anomalies in the lunar gravitational field due to unexpected concentratio

of mass, or “mascons” as they came to be called, lying beneath the lunar surface. 

Apollo Missions7

Just as NASA had assigned tracking and data acquisition responsibility for the planeta

program to JPL, it assigned tracking and data acquisition responsibility for the Apol

program to the Goddard Space Flight Center (GSFC), Greenbelt, Maryland. And, ju

as JPL built the DSN for its planetary program, GSFC built the Manned Space Flig

Network (MSFN) for supporting Apollo. The MSFN comprised two types of trackin

networks. The first consisted of a large number of 9-m stations to handle the Apol

spacecraft during Earth-orbit operations, while the second network consisted of thr

26-m stations to handle the translunar and lunar phases of the flights. For obvious re

sons, the 26-m stations of the MSFN were located near the DSN stations at Goldston

Canberra, and Madrid. 

Although the MSFN provided the prime network for tracking and data acquisition su

port for the Apollo flights, the DSN also contributed a great deal of technology an

facility support to Apollo. The DSN provided the MSFN with S-band receiving, tran

mitting and ranging equipment and computer software for lunar trajectory orb

determination purposes. Also, because the MSFN stations were (intentionally) very sim

ilar in design to the DSN stations, it was decided to equip one DSN station at ea

longitude (DSS 11, DSS 61 and DSS 42) with sufficient MSFN equipment to act 

backup for the prime MSFN 26-m stations at the same site, or one nearby. These becam

known as the “mutual” stations. Corliss has described this aspect of the JPL/DSN ro

in Apollo in his account of the history of the Piloted Space Flight Network (MSFN

A second control room called the MSFN wing was added to each DSN station an

connected via a microwave link to the nearby prime Apollo station. The MSFN win

housed the special Apollo transmitting and receiving equipment, the MSFN electroni

and recorders, and the switching connections that allowed the single DSN 26-m ante

na to be used for tracking either deep space or Apollo spacecraft. 

By mutual agreement between JPL and GSFC, Apollo mission operations at both th

DSN mutual station and the MSFN prime station were directed by a single coordin

tor provided by the MSFN at each complex. This operational arrangement proved 

56

Uplink-Downlink: A History of the Deep Space Networ
be so effective that it was used without change for all the Apollo flights, beginning wi

the Apollo 4 test flights in 1967 until the program concluded with Apollo 17 in 197

Following the success of the early test flights, DSN support for the Apollo progra

expanded to include the Goldstone 64-m antenna as backup for special events and eme

gencies. To make this possible, equipment was added to the receivers at the 64-m antenn

to allow the Apollo downlink signals to be transferred several miles via microwave lin

to the prime MSFN station for processing and onward transmission to the Apollo Missio

Control Center in Houston. Furthermore, during Apollo tracks, the 64-m antenna wou

have to be driven by computer generated pointing data derived from Apollo spacecra

trajectory information provided by the MSFN. 

These new interfaces, implemented and tested in great haste, were completed just in tim

for the first piloted lunar orbit flight on Apollo 8 in 1968. The then new 64-m ante

na at Goldstone was called upon to provide backup support for the 26-m MSFN antenn

for receiving television signals for public broadcast while the spacecraft was en route 

and from the Moon and in orbit around the Moon. The arrangement worked perfect

and from then on the Goldstone 64-m antenna was used on a regular basis to provi

critical and, in some cases, emergency (Apollo 13) support for all Apollo missions.

Apollo 13 was the third piloted mission with the Moon as its destination, and a landin

and return to Earth as its objective. The mutual stations of the DSN, together with th

big Mars antenna (DSS 14) at Goldstone, had been scheduled to provide the backup co

erage for the MSFN prime stations as was normal practice by the time of Apollo 13.

After the Saturn V launch from Cape Kennedy on 11 April 1970, the mission pr

ceeded “nominally.” The DSN stations commenced to follow the detailed tracking schedu

developed to minimize impact to the Mariner 1969 Mars spacecraft, then in its exten

ed mission. All went well until Apollo 13 was making its third pass over Goldstone o

14 April. At that point, about 55 hours into the mission, the unthinkable happenedæa

explosion in an onboard oxygen tank rendered the Lunar Service Module, with all 

redundant systems, useless. All mission objectives, except return to Earth, were aba

doned. While the mission controllers at Houston set about trying to recover the cre

all tracking stations were placed on high alert for the spacecraft emergency. The Goldston

Mars antenna was immediately requested to extend its tracking coverage of the curre

and all subsequent Apollo 13 passes, to the maximum possible, horizon to horizon. 

The unique capabilities of the 64-meter antenna were about to be demonstrated on

again. To conserve electrical power, the spacecraft began transmitting with low pow

5

The Mariner Era: 1961–1974
through its low-gain omnidirectional antenna, an emergency procedure which result

in a much weakened downlink. Because of its great receiving capability, DSS 14 w

the only tracking station able to maintain contact with the disabled spacecraft and 

crew during many parts of the aborted mission. Even when the 26-meter stations we

able to receive the downlink, the improved clarity of the astronauts’ voice channels whe

DSS 14 came into view was of great assistance and encouragement to those in dang

during the subsequent recovery efforts.

After the astronauts were safe and the mission concluded, the DSN received the fo

lowing appreciative message from the director of flight operations at Houston. “We wi

to commend the entire Network for their superior performance in support of Apollo 1

In the midst of this most difficult and critical mission, it was extremely reassuring 

have a Network with so few anomalies and one which provided us with urgently nee

ed voice and data to bring the crew back safely. We thank you for your outstandin

support.” Cognizance of the mutual stations passed to the DSN at completion of th

Apollo program in 1972, and much of the electronics technology from the wing st

tions was subsequently incorporated into DSN systems. 

58

Uplink-Downlink: A History of the Deep Space Networ
THE DEEP SPACE INSTRUMENTATION FACILITY (DSIF)

When the Mariner Era opened in 1961, the network, then known as the Deep Spa

Instrumentation Facility (DSIF), consisted of three stations—one at Goldstone, Californ

another at Woomera, Australia, in the desert 320 kilometers north of Adelaide; and 

third near Johannesburg, South Africa. In addition to its 26-m diameter dish antenn

each station had receive and transmit capabilities at a frequency of 960 MHz (L-band

and could process and record telemetry data at low data rates from the JPL-design

space probes. Telephone and teletype circuits linked each site to a simple control an

coordination center at JPL. These circuits were carried between continents via unders

cable, and by land line, or in the case of Johannesburg, by a high-frequency radio lin

to their ultimate destination.

At that time, the loose organizational structure of JPL allowed for a great deal of inte

action between the technical groups responsible for the spacecraft and its operation, an

the groups responsible for the development, implementation, and operation of the DSI

This was of prime importance in the area of telecommunications, where it was esse

tial that the spacecraft radio system was designed to be compatible with the radio system

installed at the tracking stations. While the spacecraft and tracking station design grou

each focused on their individual design issues, important questions of “telecommunic

tion compatibility” were responded to, informally, by the engineers involved. It was 

carryover from earlier times, when the spacecraft radio and DSIF radio systems had bee

designed and built in the same technical division at JPL. This situation soon change

however, and the question of telecommunications compatibility, with all its ramific

tions, became a major concern at JPL as the NASA space program gathered momentum

Mission Operations was another factor that dominated the planning processes for ear

deep space missions. Determining and controlling the flight path of a spacecraft, d

playing and analyzing the engineering and scientific data received from it, selecting an

issuing commands to the spacecraft, and coordinating the activities of the worldwi

stations of the DSIF and the communications links connecting them to JPL, are all pa

of Mission Operations. This specialized activity is conducted in a central location call

the Flight Operations Control Center.

As early as 1960, JPL had completed studies for a facility that could handle missio

operations not only for the forthcoming Ranger mission, but also for all future spa

missions. Plans called for a Space Flight Operations Facility consisting of the equipmen

computer programs, and groups of technical and operations personnel that would car

out these and all other functions required to fly the Ranger missions. The facility wou

5

The Mariner Era: 1961–1974
be located in a single building at JPL, and the same teams would work each of the m

sions to ensure continuity of experience and expertise.

In the short time available before the first Ranger launch, a temporary facility was esta

lished next to the existing computer room. Blackboards and pinboards to post curre

flight status lined the walls, desks, phones, calculating machines, and teletype machin

stood wherever space permitted. Later, a few console displays were added for closed c

cuit television display of printouts from the large mainframe IBM 7040 computers 

the adjacent computer room. A large static display board showed the status of the DS

stations and the communications links between them.

When it became obvious that the makeshift facility would be inadequate even for m

sions in the immediate future, planning and funding for the much larger permane

facility was accelerated. Designed specifically for spaceflight operations, the Space Flig

Operations Facility (SFOF) was completed and began supporting flight missions in 196

A separate control center for directing the expanded operational functions of the Netwo

occupied a large portion of the new SFOF as shown in Figure 2-4.

60

Uplink-Downlink: A History of the Deep Space Networ

Figure 2-4. Network Operations Control Center (NOCC) at JPL, 1969. Refurbished many tim

since then, and organized in several different ways to meet the expanding needs of the DSN, t

NOCC continued to perform that vital function through 1997. 
The Facility (DSIF) Becomes the Network (DSN)

In a memo to senior staff dated 24 December 1963, the Director of JPL, William H

Pickering, redefined the responsibilities of the DSIF to include “all mission-indepen

ent portions of the Space Flight Operations Facility,” in addition to the existing responsibili

for the tracking stations, the communications system linking them to JPL. The com

bined organizational structure was named the Deep Space Network (DSN) and wou

be directed by Eberhardt Rechtin, with the functional title of assistant laboratory dire

tor for tracking and data acquisition.

L-band to S-band

At this time also, a most significant engineering change was being made in the DSN

It concerned the change to a higher operating frequency for the uplinks and downlink

Mainly as a matter of convenience and expediency, the original receivers and transm

ters in the DSN had been designed in 1957 and 1958 to operate at a frequency of 96

MHz. In telecommunications terminology, 960 MHz lies within a narrow band of fr

quencies identified as L-band. The Ranger spacecraft radio system had to match th

frequency to be compatible so that it too operated at L-band. However, there are si

nificant advantages to the uplink and downlink performance to be had from operatin

at a much higher frequency of 2,200 MHz, or S-band. 

By 1963, the availability of new radio frequency amplifiers and transmitters, which wou

operate well at S-band, allowed the DSN to take advantage of the better uplink an

downlink performance at the higher frequencies. With an eye to the requirements 

future missions, the DSN set about converting all the tracking stations from L-band 

S-band. But where would that leave the Ranger program about to restart its lunar fligh

and how would it affect the recently approved Mariner missions to Mars? 

The solution devised by DSN engineers was to install S-band to L-band conversion equi

ment at the stations in parallel with the older L-band equipment. This would accommoda

the remaining four Rangers and the first two Mariner missions to Venus on L-band. 

could also provide for the later Mariner missions to Mars and the proposed Survey

missions, both of which would use the more efficient S-band uplinks and downlink

The L/S-band converter would remain in place until the end of the L-band missions, b

which time a new, fully S-band system would be in place. The L/S-band converters wou

then be removed and the conversion to the more efficient S-band operation would 

complete. All missions from then on would be on S-band. Of all the improvements 

the early years of the DSN, the move to S-band was probably the most significant. 

6

The Mariner Era: 1961–1974
Improvements for the Mariner Mars Missions 

The Mariner 1964 Mars missions were the first in which the DSN would use the new

implemented L/S-band capability to adapt the spacecraft S-band downlink to suit th

existing DSN L-band receivers. The capability to send commands to the spacecraft wou

be provided by 10-kW transmitters recently installed at Goldstone-Pioneer, Johannesbur

and Woomera stations.

In addition to the uplink/downlink improvements accruing from the change to S-ban

significant improvements to navigation accuracy were expected from the introduction 

atomic clocks throughout the DSN to replace the less stable crystal controlled oscill

tors. These rubidium frequency standards improved the quality of the radio Doppl

data provided to the spacecraft navigators by the DSN stations, enabling them in tu

to improve the trajectory determination process necessary to deliver the spacecraft to 

small aim point in the vicinity of Mars. 

Improvements in the NASA ground communications system (NASCOM), which co

nected the far-flung stations of the DSN to the Flight Control Center at JPL, ha

already taken place. Teletype links, voice, and high speed data circuits using a worl

wide network of microwave links, and undersea cables and radio circuits were connect

to a central communications center at the NASA Goddard Space Flight Center 

Greenbelt, Maryland. From there the circuits could be distributed to JPL and oth

NASA Centers scattered throughout USA, as required. The DSN could call o

NASCOM to bring up the communications necessary to support a particular mi

sion whenever needed. When the mission was completed, the circuits were turne

back to NASCOM to be used for some other NASA space mission, maybe at a d

ferent NASA Center. 

By the end of 1964, the primitive Flight Operations Control Center used for th

first Ranger missions had been superseded by the newly completed Space Flig

Operations Facility (SFOF). In a dual string computer arrangement, new IBM 709

computers performed the data processing for the Mariner 3 and 4 missions to Mar

while the Ranger processing was still carried out on a later version of the origin

7040 machines. This arrangement minimized the need for changes to the existin

Ranger software.

In the spacious facilities of the new SFOF building, a large high ceiling room in th

middle of the first floor housed the new Mission Control Center. An attractive entran

lobby with reception desk and space-related displays occupied the front of the buil

62

Uplink-Downlink: A History of the Deep Space Networ
ing, while offices and conference rooms for the various teams of flight project pe

sonnel surrounded a DSN Control Room on the other three sides. In the hu

basement below the Control Room, engineers in the DSN Communications Termin

monitored, coordinated, and routed the flow of voices and data between the station

the DSN Controllers above them, and the data processing computers on the secon

and third floors of the SFOF. An elaborate internal communications system enable

all the users of the SFOF to access and direct data to and from sources and des

nations as their duties and authority required during the mission. The Facility w

designed to run 24 hours a day, and incorporated a generator-driven “uninterrup

ible power supply” that would supply primary power if the commercial power faile

for any reason. During critical parts of a mission, the generators would be turne

on anyway to ensure that the SFOF would not suffer any kind of a “glitch” whi

critical mission operations were in progress. The muffled roar of the JPL generato

always informed the quiet neighborhood that something important was going on 

the Lab.

Over the course of thirty years, 1964 to 1994, the management responsibility for th

large data processing facilities in the SFOF passed back and forth several times betwee

the DSN and the Flight Project offices at JPL, depending on the current “financial c

mate” at NASA Headquarters. 

However, responsibility for the two DSN control functions, Network Control an

Ground Communications Control, always remained in the hands of the DSN. Th

consolidation of these vital functions, together with expansion of the Network itse

benefited from a continuum of long-term planning and management. As a result, th

DSN was perceived from time to time to have a “monolithic structure” by oth

organizations within the JPL and, indeed, even by NASA Headquarters. Good rel

tions with NASA were essential to the well-being of continued JPL involvement 

the planetary space program. Nowhere was this recognized more acutely than in th

Tracking and Data Acquisition Office at JPL, where the encouragement of freque

and open channels of communication between DSN personnel and NASA on DSN

related matters did much to improve working relationships and dispel the “monolithi

image of the DSN in those years. With the beginning of the S-band missions an

the advent of the SFOF containing the DSN Network and Communications Contr

Centers, as well as the Mission Operations Control Center and its data processin

facilities, the DSN began to assume the form, and much of the substance, of th

modern DSN.

6

The Mariner Era: 1961–1974
The Need for a Second Network 

To support the more sophisticated missions of the 1965 to 1968 period, the DSN re

ognized the need to expand and improve its communications, mission, and netwo

control capabilities. The two major lunar missions nearing launch readiness, Lunar Orbit

and Surveyor, would pave the way for the start of the Apollo program and would tran

mit data streams at thousands of data bits per second rather than the tens or hundre

of bits per second received from the Mariners and Rangers. The increased complexity 

the spacecraft would require expanded and faster monitor, control, and display facilitie

For the first time, the DSN began to find that the simultaneous presence of sever

spacecraft on missions to different destinations created new problems in network an

mission control. The vexing problem of DSN “antenna scheduling” began to arise 

several spacecraft began to demand tracking coverage from the single DSN antenn

available at each longitude. The difficulty of assigning priority among competing spac

craft whose view periods overlapped at a particular antenna site was to prove intractab

for many years. The problem was exacerbated by competition between flight projec

from NASA Centers other than JPL, each of which felt entitled to equal consider

tion, for the limited DSN resources. The DSN was placed in the impossible situatio

of arbitrating the claims for priority consideration. The regular “Network Schedulin

meetings conducted by the DSN often resulted in the establishment of priorities th

were determined more by the dominant personalities in the group than by the re

needs of the projects.

With all of these imminent new requirements in mind, NASA decided to embark o

a program to construct a second network of DSN stations. Arguments as to where th

stations were to be located were complicated not only by technical considerations, b

by political and international considerations. 

There were already two stations at Goldstone, one at the Pioneer site and a second 

the Echo site. Eventually, NASA decided to build two new stations, one at Robled

about 65 kilometers west of Madrid, Spain, and the other at Tidbinbilla, about 16 kil

meters from Canberra, Australia.

NASA looked to the Spanish Navy’s Bureau of Yards and Docks to design and co

struct the Robledo station. For its new facilities in Australia, NASA dealt with th

Australian Government Department of Supply through its representative, Robert A. Lesl

64

Uplink-Downlink: A History of the Deep Space Networ
As an Australian foreign national, Robert A. Leslie played a major role in shapin

the relationship between NASA-JPL and the Australian government, on whose goo

offices NASA depended for support of its several tracking stations in that countr

With family origins in the state of Victoria, Australia, and an honors degree in ele

trical engineering from the University of Melbourne (1947), Leslie had worked o

radio controlled pilotless aircraft for the military in both England and Australia f

fifteen years before he encountered NASA. He was a high-ranking officer with th

Australian Public (Civil) Service (an affiliation that he retained throughout his caree

when, in 1963, he became the Australian government’s representative for NASA

new deep space tracking facility being built at Tidbinbilla, near Canberra in sout

eastern Australia.

As might be expected, the success of a NASA venture in a foreign country depen

ed to a large extent on the personalities of the people who were directly involved o

each side of the international interface. The foundation for the success of what lat

became the Canberra Deep Space Communications Complex (CDSCC) was, in n

small part, due to Bob Leslie’s personal ability to “get along” with people at all le

els. In representing the Australian side of negotiations between NASA and JPL, Bo

Leslie was firm but gracious, capable, and friendly. His unassuming “paternal” ma

ner endeared him alike to counterparts at NASA, his colleagues at JPL, and his sta

in Australia. 

Along with a few key Australian technical staff members, Leslie spent a year at Goldston

assembling and testing the electronic equipment that would subsequently be reassem

bled at Tidbinbilla to complete the first 26-meter tracking station (DSS 42) at th

new site. He was the first director of the new Complex when it began service in th

Network in 1965. It was there that he established the procedures and protocols o

which all future DSN operational interactions between JPL and the Australian st

tions would be based. 

A few years later, in 1969, Leslie left the “hands-on” environment of the deep spa

tracking station to head the Australian Space Office, a branch of the Australian Governme

that, under various names and government administrations, would guide future expa

sion and consolidation of all NASA facilities in Australia. In that capacity, his charm

experience, and wisdom served the DSN well. 

Leslie’s build was stocky and solid, his appearance craggy, his attitude “laid back

Cheerful, sociable, easy to talk to, and blessed with a good sense of humor, he w

held in high regard by everyone he met, Australian or American. Tennis was his spor

6

The Mariner Era: 1961–1974
fishing his hobby, and “do-it-yourself” home building his passion. In his young

days, he actually excavated the ground with shovel and wheelbarrow and single-han

edly built the family swimming pool at his home in Canberra. Many a JPL engine

enjoyed a poolside barbecue at the Leslie home in the course of a technical visit 

the station.

Robert Leslie retired in 1983 and died in Canberra, Australia, in 1996.

By mid-1965, the two new stations were completed and declared operational. The DS

then had two stations in Australia, (Woomera and Tidbinbilla), one in Spain, and on

in South Africa. In addition, a permanent spacecraft monitoring station had been bu

at Cape Canaveral to replace the temporary facility with its hand-steered tracking ante

na. Impressive as this growth was, still greater changes were in progress.

Larger Antennas Are Needed

Consistent with the JPL vision for missions to more distant planets, and more powe

ful communications links to support them, the DSN had long recognized a need f

larger antennas, that is, larger than the existing 26-m antennas. Studies had shown th

a diameter of 64 meters was about the maximum practical limit to an antenna whi

would have sufficient stability and structural integrity for DSN purposes. Interest 

building a giant new antenna of that size, employing radical new design and constru

tion techniques, became a reality as early as 1962 at NASA and JPL. Feasibility stud

contracts for an advanced antenna had already been issued to numerous U.S. corpor

tions and, finally in January 1963, the Rohr Corporation was selected to build th

antenna at a suitable site a few miles from the existing Echo and Pioneer locations 

Goldstone. Since the advanced antenna was originally intended to support the first m

sions to Mars, the site was appropriately called “the Mars site.”

Design work began immediately (1963), and procurement and fabrication of ste

components started a year later. Roads, concrete foundations, alidade structure, an

diesel generator buildings were completed in 1964, followed by the control roo

and elevation bearings. The supporting framework for the antenna panels followe

next, and by mid-1966, the 64-meter Mars Antenna was ready for service. Althoug

the first signals from Mars—transmitted by Mariner 4—were detected in Marc

1966, a great deal of performance testing, personnel training, and calibration remaine

to be completed before the Mars antenna was considered a fully operational add

tion to the DSN.

66

Uplink-Downlink: A History of the Deep Space Networ
6

The Mariner Era: 1961–1974

Figure 2-5. Side elevation of the 64-meter azimuth-elevation antenna at Goldstone, 1966.

PRIMARY REFLECTOR STRUCTURE

ELEVATION WHEEL AND

BACK UP STRUCTURE

ANGLE-DATA SUBSYSTEM

PLATFORM

ELEVATION

BEARING ASSEMBLY

INSTRUMENT TOWER

ELEVATION DRIVE

ASSEMBLY

AZIMUTH RADIAL

BEARING

25.3 (83)

8.5 (28)

10.1 (33)

AZIMUTH DRIVE

ASSEMBLY

0.6 (2)

AZIMUTH HYDROSTATIC

NOTE: DIMENSIONS ARE IN METERS AND (FEET) CABLE WRAP-UP THRUST BEARING

PEDESTAL

PRIMARY REFLECTOR 

SURFACE

ALIDADE BUILDING

ALIDADE

SUBREFLECTOR

FEED SYSTEM

QUADRIPOD SUPPORT

FEED CONE HOIST

37.9 (124 ft, 2 3/8 in)
Designed to remain operating in wind speeds as high as 80 km per hour, the Ma

antenna was constructed of massive steel beams, which, together with its pedestal, weigh

about 33 million kilograms. At wind speeds exceeding 80 km per hour, the antenna w

stowed in a fixed position to protect it from permanent damage. In that position 

68

Uplink-Downlink: A History of the Deep Space Networ

Figure 2-6. The 64-meter antenna at Goldstone, 1966. The pickup truck parked to the rig

side of the pedestal gives an impression of the immense size of the antenna.
could withstand hurricane force winds. The dish, and its azimuth-elevation mountin

atop the pedestal, weighed nearly 13 million kg. The structure rotated in azimuth o

three flat bearing surfaces that floated on a pressurized film of oil, about the thickne

of a sheet of paper. The reflecting area of the dish surface was 3,850 square meters. 

could be pointed to a given position in space with an accuracy of 0.006 degree. Th

major structural components and dimensions of the 64-m antenna are evident in th

side elevation shown in Figure 2-5.

In a single, major step forward, the Mars antenna provided the DSN with mo

than six times the transmitting power and receiving sensitivity of the 26-meter ante

nas, and more than doubled their tracking range. This was a significant new capabili

indeed. But, important as it was, it was only one in a series of stepwise improv

ments that took place in the DSN in the mid-1960s. A photograph of the ne

64-meter antenna at Goldstone, taken soon after its completion in mid-1966, 

shown in Figure 2-6.

Most of the credit for the conceptual design of the Goldstone 64-m antenna, the first 

its kind ever built for tracking planetary spacecraft, went to a brilliant electrical engine

who had come to JPL originally in 1951 to work on missile tracking systems during th

Corporal and Sergeant tests at White Sands. His name was William D. Merrick. In 195

it was Bill Merrick who masterminded the design and construction of the first two 26-

antennas at Goldstone before taking up the job of project manager for the Advanc

Antenna System. The “Hard Core” Design Team that Merrick formed to carry out th

complex design and analysis task for the new 64-m antenna contained the best enginee

ing talent in the fields of servos, microwaves, mechanical, optical, structural, civil, electric

and hydraulic engineering, stress analysis and contract management that could be foun

at JPL or elsewhere. 

He managed his “Hard Core” team, and the contractors who eventually built the ante

na, in a somewhat unorthodox manner, but the on-time, in-budget and to-specificatio

end result demonstrated the efficacy of his management style.

Although he insisted on high standards of performance from his people, his propensi

for practical jokes and his sense of humor endeared him to those who worked on h

team. Those who needed to direct or limit his activities found him difficult. He thoug

of himself as a person who got things done regardless of obstacles such as budget co

straints, administrative orders, or alternative opinions that stood in his path. He cou

always find a way around them.

6

The Mariner Era: 1961–1974
When the Goldstone 64-m antenna was completed in 1966, it was regarded by man

who appreciated the effort that he put into it as a testament to Bill Merrick. After th

64-m antennas in Spain and Australia were completed, Merrick moved from the “hand

on” engineering, at which he excelled, to a staff position which offered little challen

for his special talents. 

Bill Merrick retired from JPL in 1984 to take up a position in industry, and died 

his home in Ventura, California, in 1997.

Incremental Improvements in the Network

Important as it was, the new 64-m antenna at Goldstone was only one of many improv

ments in technology and management that were added to the Network in the mid-1960

Like the 64-m antenna, each change represented an incremental increase in the over

capability and performance of the Network. As Corliss put it, “The DSN did not su

denly change from a lunar to a planetary network, or a low-bit-rate network to 

high-bit-rate network, or a network burdened with mission-dependent equipment to 

multi-mission network. The DSN was always being upgraded, some of the steps we

small, some of the others were big.” Although there were many changes in many area

some small, some large, among the most important at this time was the improveme

in the DSN ranging system.

The technique of measuring the range (distance) from a reference point on Earth, to 

spacecraft at lunar distance, to an accuracy of a few centimeters was one thing. To d

the same thing for a spacecraft at planetary distance required a significant new tec

nique for measurement of range. A Lunar Ranging system, known as the Mark I, w

already in place in the mid-1960s. Although it was designed for the lunar missions, 

had successfully tracked Mariner 5 out to nearly ten times the distance of the Moon

Planetary ranging, however, would require a hundredfold increase in capability. This cou

be achieved with new and more complex range codes transmitted to the spacecraft on th

uplink, and new methods of detecting and decoding the range code retransmitted fro

the spacecraft on the downlink. More precise methods for calibrating the system, and f

measuring time, would also be required. Two planetary ranging systems were developed 

this period, one by Robert C. Tausworthe, the other by Warren L. Martin. The two sy

tems were aptly named the “Tau” and the “Mu.” In Tausworthe’s design, the time del

between a pseudo-random code transmitted on the uplink and returned on the downlin

was used to measure the range of the spacecraft. Martin’s design used a sequential bina

code, assisted by a Doppler rate-aided function to carry out the decoding, for range mea

70

Uplink-Downlink: A History of the Deep Space Networ
urement. This design also automatically produced a type of data called DRVID, f

Differenced Range versus Integrated Doppler, which allowed the range data to be co

rected for the effects of charged particles along the path between spacecraft and trackin

station. Together these improvements extended the performance of the Mu system to th

point where high-precision ranging measurements were possible out to a range of 2.6 AU

The Mark I, and a later Mark IA version, was used for the Lunar Orbiter and Survey

missions in 1966 and 1967. The Tau planetary ranging system saw its first operation

use on Mariner 5 in 1967 and 1968, and an improved and more stable version of th

Tau system was used from 1969 to 1971 for Mariners 6 and 7. Later still, the Mu ran

ing system appeared in the Network and was used for relativity experiments on th

extended missions of Mariners 6 and 7 in 1970. 

For the accurate ranging required by the Lunar Orbiter mission, the electronic cloc

at the various tracking stations had to be synchronized to within 50 microseconds 

the master clock at Goldstone. In the early days, the DSIF had to rely on radio si

nals from WWV for station time-keeping purposes. The most accurate measurement 

the time was in milliseconds rather than microseconds. Later, transportable cesium atom

ic clocks from the National Bureau of Standards offered improved accuracy for statio

time synchronization. However, this method proved to be too expensive and inconve

ient for operational use. A more operationally convenient method of time synchronizatio

using the spacecraft itself was eventually implemented for Lunar Orbiter and improv

the accuracy to 20 microseconds.

As usual though, the DSN was looking for something better. It showed up in 196

as the “Moon-bounce Time Sync” scheme. This depended upon the propagation del

of a precision timed X-band signal which was transmitted from the Goldstone Ven

station to each of the overseas stations during their mutual lunar-view periods. Th

Goldstone Venus station acted as master timekeeper and timing signals reached th

desired stations via the Moon. By 1968, the DSN was setting its clocks to an acc

racy of 5 microseconds using this technique, which had been adopted for operation

use throughout the Network.8

Driven by the rapidly increasing data rates being transmitted by the new spacecraft com

ing into the DSN, the capability of the ground communications system had to 

expanded to permit the tracking stations to return data to JPL as rapidly as possib

More stations needed more operational voice and teletype traffic to control them

Consequently, in 1967, a new computer-based teletype communications switcher w

7

The Mariner Era: 1961–1974
installed in the Com Center in the SFOF and the high-speed data circuits were upgra

ed to carry 2,400 bits per second.

The SFOF, too, felt the pressure to keep up with the ever-increasing requirements for hig

er data rates on the uplinks and downlinks for the new missions. The SFOF data processin

capability was expanded to three computer strings, each comprising an IBM 7044 an

large disk memory for input/output processor functions, followed by an IBM 7094. Th

7094 was used as the primary processor for the complex calculations related to orbit dete

mination; it generated antenna pointing and receiver tuning predictions used for init

acquisition, calculated the parameters needed for spacecraft maneuvers, and manipulat

the spacecraft tracking data generated by the DSN stations. In addition, a special syste

was developed to display monitor and performance data for the DSN station controlle

Flight Project Requirements Become Formalized

By 1967, the interactions between the DSN and new flight projects needing DSN su

port had become very formalized. No longer were all the missions managed by JPL, whe

loose interdepartmental agreements would suffice to commit funds and resources to me

a specific JPL objective. Now, other NASA Centers were responsible for the spacecra

and its scientific payload, and the function of JPL was to provide the tracking and da

acquisition support using the resources of the DSN. Even within the JPL institution, th

changing management organization at NASA Headquarters was reflected in entirely se

arate funding channels for the flight project and the DSN organizations. This situatio

resulted in a very formal process for the presentation of flight project requirements to th

DSN, and the acceptance (or rejection) of these requirements by the DSN. 

NASA Headquarters insisted that these negotiations be set out in detail in two form

documents, the Support Instrumentation Requirements Document (SIRD) for the flig

projects, and the NASA Support Plan (NSP) for the DSN. Before any flight proje

could begin to effectively design its mission, it not only had to have a signed SIR

from one office of NASA Headquarters but a signed NSP from another. With these 

hand, a newly approved flight project could truly begin. In the years ahead, the rel

tionship between the DSN and all flight projects would always be a reflection, for bett

or for worse, of the SIRD/NSP negotiations.

Finally, the DSN was beginning to use computer assistance to resolve mounting conflic

for station time, not only for spacecraft tracking purposes but also for station maintenanc

implementation of new hardware and software, and testing time. Also, the stations we

becoming much more complex, and consequently required more time for calibration, co

72

Uplink-Downlink: A History of the Deep Space Networ
figuration and check-out prior to the start of each tracking pass. In addition, the flight pro

ects were becoming less tolerant of station outages which depleted their hard won trackin

time allocation. The persistent issue of tracking time allocations would never go away; 

was ameliorated somewhat as techniques to manage it improved, but it never went awa

This was the state of the DSN when, within a very short period it found itself dea

ing with more spacecraft than any of its people could have imagined a few sho

years earlier.

The DSN Becomes a Multimission Network

Referring to this period in the history of the DSN, William Corliss wrote, “The NAS

lunar exploration program absorbed the bulk of the DSN support capability during th

1966-1968 period. Surveyor, Lunar Orbiter, and the backup support provided to th

first Apollo flights combined to utilize the DSN almost fully. The lunar program at th

time consisted of short-lived missions, a few days long, and the DSN was able to dive

some of the support necessary for the Mariner 5 shot to Venus and also accord som

support for Pioneers 6–9, which kept on operating long after the ends of their nomin

missions. Mariner 4 was also picked up again and became another example of an exten

ed mission. The new 64-meter Mars antenna was called upon to support almost all 

these missions, although not always as a prime station. The DSN during this perio

was not yet a multimission network, although it was supporting many missions simu

taneously. The DSN stations were still crowded with mission-dependent equipment an

this situation was the very antithesis of a multimission philosophy.”

These and other issues related to the general problem of data return from deep space a

discussed by Hall, Linnes, Mudgway, Siegmeth, and Thatcher9 and an excellent descri

tion of the growth of the DSN from inception through 1969 is given by Renzetti et al

To simplify the increasing problem and cost of accommodating the many differe

kinds of special telemetry and command processing equipment appearing at the trac

ing stations to support the various missions, the DSN developed a “multi-missio

philosophy. 

Instead of each flight project bringing its own equipment (and people to operate it) 

the stations, the DSN would provide a generic set of equipment capable of operatin

over a wide range of parameters at each station. Future projects would have to desig

their uplinks and downlinks to fall within the capability of the equipment provided b

the DSN. That way, all flight projects could use the same set of ground support equi

7

The Mariner Era: 1961–1974
ment, and operations costs and complexity could be reduced. With some modificatio

this concept has been preserved to the present time.

Its success has been largely due to the DSN policy of advanced development, in kee

ing the DSN capability well ahead of the flight projects’ demands to use it. The DS

was able to do this by basing its long term planning on judicious forecasting of futu

mission requirements.

By the early part of 1968, the Lunar Orbiter and Surveyor Lander missions had bee

concluded. Spectacularly successful, they had returned an avalanche of lunar surfa

and other science data, which was assimilated into the design studies for the Apol

piloted missions. 

It was not realized at the time that a DSN mission would not view the Moon aga

for nearly twenty-five years. In December 1992, a remarkable picture of the Moon 

orbit around Earth would be captured by a spacecraft called Galileo, outbound on 

mission to Jupiter and its satellites. By then, the DSN and the environment in whi

it functioned would be very different indeed.

The missions to follow over the next six years (1968–1974) would focus the DSN

attention outward to even more distant planets and to the Sun. During these years, th

DSN made enormous improvements in its operational capability to meet the requir

ments of the new planetary missions.

New telemetry and command systems with true multimission features were added throug

out the Network. Not only were these additions multimission in nature but their abili

to run at higher data rates on the uplink and downlink had been increased to 16 kil

bits per second for telemetry and 32 bits per second for the command link. New form

of coding the downlink data to improve the quality of the science data delivered to th

flight project had also been developed. 

The speed of identification and correction of problems in the Network was improv

by giving station controllers better tools to monitor and control the configuration, st

tus, and performance of remote tracking stations.

The Doppler and ranging data generated by the tracking stations and used by the flig

projects for spacecraft navigation purposes was improved in accuracy and extended in rang

Studies were made to better understand the disturbing effect of charged particles on th

radio path between the spacecraft and the DSN antennas. Thrown off by the Sun, the

74

Uplink-Downlink: A History of the Deep Space Networ
particles introduce delays in the radio path and consequent inaccuracies in the navigatio

data. Ways of calibrating out these undesirable effects were found and put into effect.

To create a realistic operational environment to train DSN operators prior to the sta

of a real mission, the DSN uses a Simulation System. Electrically generated signals ca

be programmed to simulate a real spacecraft under a variety of flight conditions. Artific

faults can be introduced and the operations personnel can be trained in the proper rea

tions. With an increasing number of more complex spacecraft coming into the Netwo

in the early 1970s, a Simulation Center was established at JPL to carry out the sim

lation tasks for all missions. Conversion assemblies at the stations allowed the individu

stations to interact with the “SIM Center” to suit their individual training needs.

The addition of “wideband” circuits that could handle data at 50 kilobits per second betwe

the Goldstone Mars station and the SFOF, and 28.5 kilobits per second to Spain an

Australia, gave the Ground Communications Facility (GCF) as it was now called, a cap

bility to deliver the increased volume of data from the now enhanced DSN to the SFO

Because the existing high speed circuits, operating at 4800 bits per second, could hand

much of the traffic formerly handled by teletype, the teletype services were phased out.

It had become obvious that the SFOF itself would not be able to cope with the deman

of the future flight projects for data processing and handling. The data streams plann

for the future Mariner and Viking missions to Mars would overwhelm the data-ha

dling capability of the old IBM 7040/7044 generation of computers. An Advanced Da

System study group recommended a completely new design for the new Mark III SFO

which involved, among other things, replacing the old machines with new IBM 360/75

No longer an appendage to the DSN, the SFOF became an autonomous organizatio

with full responsibility for supporting the flight missions. DSN responsibility in th

SFOF was redefined to cover only Network control and the data processing necessa

to carry out that function.

Openings and Closings

The tremendous improvement (a factor of six times over a 26-meter station) in uplin

and downlink performance, afforded by the 64-meter antenna at Goldstone, was offs

somewhat by the limitation of a single antenna at only one longitude. To provide th

continuous coverage with high performance required by the new missions, similar ante

nas in Spain and Australia would be needed. The viability of the 64-meter design h

already been established by the Mars station experience, and by June 1969, the Colli

7

The Mariner Era: 1961–1974
76

Uplink-Downlink: A History of the Deep Space Networ

Figure 2-7. Composition of the Deep Space Network, 1974. 
Radio Company of Richardson, Texas, had been selected to build two more 64-met

antennas. To simplify logistics and support facilities, the new antennas would be bu

near the existing 26-meter sites at Canberra, Australia, and Madrid, Spain.

Construction of the Australian antenna began soon after and was completed in thr

years, without significant delays, in mid-1972. Electronics were installed and tested an

after a period of calibration, operator training, and performance demonstration trac

ing, the station reached full operational status in April 1973. 

Although work on the Spanish antenna encountered some problems along the way, 

followed a similar pattern and was declared operational in September 1973. By this tim

a second 26-meter antenna had been added to each of the complexes at Madrid an

Canberra.

The DSN now had two networks of 26-meter antennas plus a complete network of 6

meter antennas. They would be numbered so as to indicate the areas in which th

antennas were located; 11 to 19 for Goldstone, 41 to 49 for Australia and 61 to 69 f

Spain. Thus the DSN would consist of Deep Space Station 14 (DSS 14) at Goldston

DSS 63 at Madrid, and DSS 43 at Canberra, plus the six 26-meter stations, which we

similarly identified.

At each location, the number and types of antennas continued to increase. Larger buil

ings were built to house the hundreds of racks of electronic equipment required 

control the antennas, and to transmit, receive, record, and process the spacecraft da

before it could be fed to the NASCOM communication circuits for transmission ba

to JPL. Instead of a single antenna and a modest Control Room at each longitude, the

were now several antennas, a Signal Processing Center, power station, cafeteria, labor

tory, workshops, offices, and supporting facilities. The entire establishment had becom

a Deep Space Communications Complex (DSCC)—GDSCC for Goldstone, CDSC

for Canberra, and MDSCC for Madrid.

The new complexes at Canberra and Madrid now provided the support formerly give

by Woomera and Johannesburg, both closed by NASA: Woomera for economic reason

Johannesburg for diplomatic reasons. The composition of the Network as it existed 

1974 after these closings had taken place is tabulated in Figure 2-7.

7

The Mariner Era: 1961–1974
LOOKING BACK

Born out of the challenge to the prestige of American technology created by the appea

ance of the Soviet satellite Sputnik in October of 1957, by 1974 the DSN had evolv

into the world’s largest and most sensitive radio communications and navigation netwo

for unpiloted interplanetary spacecraft engaged in the exploration of the solar system. 

From a loose collection of remote transmitting and receiving stations maintained and ope

ated by essentially dedicated engineering personnel from JPL, the DSN had matured in

a fully integrated global network of operational tracking stations, maintained and opera

ed by competent nationals of the cooperating countries in which the sites were located

It had become a worldwide organization of tracking stations, located on three con

nents and connected by high quality communications satellite and cable links to a Contr

Center in Pasadena, California. From there, a web of phone, teletype, and modem c

cuits distributed scientific data in various forms to the science community in resear

centers and universities throughout the U.S. and to several experimenters at locatio

in other countries. 

Fifteen or so years after inception, the Pioneer, Ranger, Surveyor, Lunar Orbiter, an

Mariner spacecraft had carried out scientific missions to the Moon, Sun, Mercury, Venu

Mars, and Jupiter with great success. These spacecraft were spread out in all directio

and distances throughout the solar system. During these years, the DSN was frequen

ly called upon to track as many as six such spacecraft simultaneously, the limit to th

requirements being set by the number of antennas in the DSN itself. 

Two big Voyager spacecraft were being built for 1977 missions to Jupiter. Two amb

tious Viking missions to Mars, even though they would not be launched for anoth

year, were demanding and getting most of the DSN attention.

Yet, this was the era of the Mariners. As it drew to a close, the DSN was moving towa

a new phase of development. It would be simultaneously involved with several lar

flight projects directed not by JPL, as had been the case in the Mariner program, b

by other NASA Centers or by foreign space agencies. We will refer to this period of th

DSN history as the Viking Era.

78

Uplink-Downlink: A History of the Deep Space Networ
Endnotes

1. R. Cargill Hall, Lunar Impact: A History of Project Ranger, NASA History Seri

(Washington, DC: NASA SP-4210, National Aeronautics and Spa

Administration, Scientific and Technical Information Branch, 1977).

2. William R. Corliss, “A History of the Deep Space Network,” NASA CR-15191

1976.

N. A. Renzetti, “Tracking and Data Acquisition Support for the Mariner Venus 6

Mission,” JPL Technical Memorandum TM 33-85, Vols. I–III, September 1969.

N. A. Renzetti, “Tracking and Data Acquisition Support for the Mariner Mars 196

Mission,” JPL Technical Memorandum TM 33-474, Vols. I–III, September 1971

R. P. Laeser, et al., “Tracking and Data Acquisition Support for the Mariner Ma

1971 Mission,” JPL Technical Memorandum TM 33-523, Vols. I–IV, March 197

E. K. Davis, “Mariner 10 Mission Support,” Deep Space Network Progress Repo

PR 42-27, March/April 1975, 15 June 1975, pp. 5–9.

3. Bruce C. Murray, Journey Into Space (New York: W. W. Norton, 1989).

4. Richard O. Fimmel and Earl J. Montoya, “Space Pioneers and Where Are Th

Now” (Washington, DC: NASA EP-264, Educational Affairs Division, Nation

Aeronautics and Space Administration, 1987). 

N. A. Renzetti, “Tracking and Data Acquisition Support for Pioneer Project,” JP

Technical Memorandum TM 33-426, Vols. I–IV, November 1970.

A. J. Siegmeth, “Pioneer Mission Support,” JPL Technical Report TR 13-1526, Vo

III, 15 April 1972, pp. 8–15. 

5. N. A. Renzetti, “Tracking and Data Acquisition Support for Surveyor Project,” JP

Technical Memorandum TM 33-301, Vols. I–V, December 1969.

6. J. R. Hall, “Tracking and Data System Support for the Lunar Orbiter (Project),” JP

Technical Memorandum TM 33-450, Vol. I, 15 April 1970.

7

The Mariner Era: 1961–1974
7. William R. Corliss, “Histories of the Space Tracking and Data Network (STADAN

Piloted Space Flight Network (MSFN) and NASA Communications Netwo

(NASCOM),” NASA CR-140390, June 1974.

P. S. Goodwin, “Apollo Mission Support,” The Deep Space Network, Spa

Programs Summary SPS 37-56, Vol. II, 31 March 1969, pp. 35–42. 

R. B. Hartley, “Apollo Mission Support,” JPL Technical Report TR 32-1526, Vo

X, 15 August 1972, pp. 41–48.

R. B. Hartley, “Apollo 13 Mission Support,” The Deep Space Network, Spa

Programs Summary, SPS 37-64, Vol. II, 31 August 1971, pp. 7–11.

8. Jet Propulsion Laboratory, “The Deep Space Network,” Space Program Summar

Vol. III, SPS 37-43, SPS 37-45, SPS 37-53, 1966–1968. 

9. J. R. Hall, K. W. Linnes, D. J. Mudgway, A. J. Siegmeth, J. W. Thatcher, “Th

General Problem of Data Return From Deep Space,” Space Science Reviews 8 (1968

595–664; Dordrecht-Holland: D. Reidel Publishing Co.

10. N. A. Renzetti, “A History of the Deep Space Network From Inception to Janua

1969,” JPL Technical Report TR 32-1533, Jet Propulsion Laboratory, Pasaden

California, September 1971.

80

Uplink-Downlink: A History of the Deep Space Networ
CHAPTER 

The Viking Era: 1974–1978

81
THE VIKING ERA MISSION SET

The tracking and data acquisition requirements of the Viking Mission to Mars dom

nated the engineering and operations resources of the DSN during the years 1974 throug

1978. Obviously, there were also many other missions during this period, all of the

demanding and receiving the attention of the DSN as they moved through the vario

phases of their respective missions. The Deep Space mission set for that period is show

in Figure 3-1 with the relative importance of each noted.

Figure 3-1. The Viking Era mission set.

Primary Missions are those in the prime mission phase of their project. Secondary Missio

are those that have completed their prime mission objectives and are in an extend

mission phase. Future Missions are those which, although not yet launched, have si

nificant prelaunch support demands on DSN attention and resources. Figure 3-1 al

shows the spacecraft that were moving through these mission phases during this arb

trarily defined Viking Era. Mariner 10, for example, was engaged in multiple encounte

with Venus and Mercury. Pioneers 6-9 were observing interplanetary fields and charg

particle phenomena from solar orbits inward and outward of Earth orbit. Pioneers 1

and 11 were making the first encounters with the planet Jupiter.

Secondary Misions

Future Missions

1979

1978

1977

1976

1975

1974 Mar10 P6-9 P10,11 He1 Vk1 Vk2 He2 Vg2 Vg1 P12 Pm/p

Primary Missions

Viking Era

Viking Era

Deep Space Network Mission Set

82

Uplink-Downlink: A History of the Deep Space Networ
Also during this era, two Helios spacecraft from the Federal Republic of Germany (We

Germany), the first of the non-NASA spacecraft to be supported by the DSN, we

launched, then traveled on helio-centric orbits around the Sun. The long-awaited gran

tour of the solar system was also inaugurated with the launch of the two JPL Voyag

spacecraft. Voyagers 1 and 2 would also become dominating influences on DSN oper

tions and engineering and establish an era of their own. Toward the end of the Vikin

Era, two other missions would revisit Venus: the Pioneer Venus Orbiter for remote sen

ing, and the Pioneer Multiprobe to determine the composition and structure of the Venusia

atmosphere.

As the Viking Era opened, the Viking project was replanning its previously cancell

1973 Mars Lander missions for two launches in 1976. Strongly managed by the Langl

Research Center in Hampton, Virginia, Viking was to dominate the DSN scene befor

during, and after the rather short Prime Mission, and for that reason it seems appr

priate to consider these years as the Viking Era.

It would be the tracking and data acquisition requirements for the new missions in th

Viking Era Mission Set that would provide the rationale for DSN Operations an

Engineering activity in the years 1974 through 1978.

8

The Viking Era: 1974–1978
THE NETWORK

The DSN moved from the Mariner Era into the Viking Era with one complete su

network of 64-meter antennas and two complete subnetworks of 26-meter antenna

The 64-meter antennas at DSS 14 Goldstone (Mars), DSS 43 Canberra (Tidbinbilla

and DSS 63 Madrid (Robledo) had come into operational service in 1966, 1973, an

1974, respectively. Each station could transmit and receive on S-band. In addition 

S-band, DSS 14 could receive on X-band.

At the Canberra and Madrid Complexes, one of the 26-meter antennas was colocated wi

the 64-meter antennas at the Tidbinbilla and Robledo sites, while the second 26-met

antennas were located at the Honeysuckle and Cebreros sites. Goldstone 26-meter ante

nas were at separate sites (Pioneer and Echo). The 26-meter antennas at Goldstone, Canberr

and Madrid (DSS 11, 42, and 61) became operational on S-band in 1964, 1965, an

1965, respectively, while DSS 12, 44, and 62 became operational in 1965, 1974, an

1966, respectively. All 26-meter antennas had S-band receive-and-transmit capability.

Operations control and signal processing for DSS 43/42 and DSS 63/61 were conduct

from a single control facility at each site. For this reason, these stations were called conjoi

stations. The remaining stations were operated and controlled by individual control cente

By the end of the Viking Era in 1978, work was in progress to convert one 26-met

subnet (DSS 12, 42, 61) to 34-meter, S/X-band capability. The first station in the serie

DSS 12, had been completed in October and was supporting inflight operations wi

its new capability in November. A block diagram of the DSN as it appeared toward th

end of 1978 is shown in Figure 3-2.

The Viking Era would see many significant changes in the structure, technical capab

ities, and operational management of the DSN.

The spacecraft and mission control functions for the inflight projects would be conduct

from a facility now called the Mission Control and Computing Center (MCCC). Th

MCCC would be a completely separate entity from the DSN. Located in Building 23

at JPL, the former Space Flight Operations Facility (SFOF), it would house the Missio

Director and his mission operations teams, as well as the computers and data processin

facilities needed to process, distribute, and display the real-time mission data as th

arrived from the DSN tracking stations. A clear, manageable interface for the transfer 

data between the DSN and MCCC had been defined, and all DSN data were deliver

by the Ground Communications Facility (GCF) to that interface in accordance with pr

established specifications regarding the quality, quantity, and validity of the data.

84

Uplink-Downlink: A History of the Deep Space Networ
8

The Viking Era: 1974–1978

Figure 3-2. Functional block diagram of the Deep Space Network, 1978.

DSS 14

64-METER

DSS 43

64-METER

DSS 42

26-METER

DSS 44

26-METER

DSS 63

64-METER

DSS 61

26-METER

DSS 62

26-METER

COMM = GROUND COMMUNICATIONS

DS = DEEP SPACE

DSS = DEEP SPACE STATION

NASCOM = NASA COMMUNICATIONS

POCC = PROJECT OPERATIONS CONTROL CENTER

SPC = SIGNAL PROCESSING CENTER

DSS 12

34-METER

DSS 11

26-METER

Ts/Rs, Rx

Ts/Rs, Rx

Ts/Rs

Ts/Rs

Ts/Rs, Rx

Ts/Rs

Ts/Rs

Tx/Rs, Rx

Ts/Rs

GOLDSTONE

SPC 10

MARS

SPC 40

TIDBINBILLA

SPC 60

ROBLEDO

COMM

COMM COMM

JPL CENTRAL

COMM TERMINAL

JPL

MISSION CONTROL

AND

COMPUTING CENTER

OTHER POCC’S

OTHER CENTERS

GSFC

NASCOM

CANBERRA

HONEYSUCKLE CEBREROS

MADRID

JPL

NETWORK OPERATIONS

CONTROL CENTER

ECHO

PIONEER
As individual flight missions were completed, they moved out of the MCCC and ne

missions took their place. Some flight projects, notably Pioneer and Helios, elected 

establish Project Operations Control Centers (POCCs) at their own institutions. In the

cases, the GCF routed the DSN data directly to the POCCs.

The operations control and management functions for the Network were conduct

from a facility now called the Network Operations Control Center (NOCC). It, to

was located in the SFOF Building at JPL and housed the DSN Operations Teams an

the hardware and software necessary to generate and transmit the data products such 

predicts, sequence of events, configurations, and schedules needed by the stations to co

duct real-time spacecraft tracking operations. At the NOCC, station controllers coordinat

activities with the remote site operations personnel. The controllers acted as a sing

point of contact for the flight Project Mission Operations people in the MCCC (

POCC) and the DSN on matters concerning real-time flight operations.

All data passing to and from the Deep Space Stations (DSSs) and the MCCC also pass

in parallel through the NOCC. There it was monitored, validated for quality and com

pleteness, recorded, and eventually transferred to the flight project in the form of 

digital tape called an Intermediate Data Record (IDR). A very extensive communic

tions, monitoring, and display capability was provided in the NOCC to allow the DS

real-time operations staff to perform all of these functions.

The operations control and communications circuit coordination functions for the GC

were carried out in the Central Communications Terminal (CCT), also located in th

SFOF Building at JPL. In the basement of the SFOF resided the complex terminal an

switching equipment for the worldwide network of communications circuits on whi

the DSN depended for its voice, high-speed, and wide-band data communications wi

the remote tracking stations of the DSN. Working closely with the NOCC real-tim

operations teams, the GCF Operations Teams performed similar functions of monito

ing and coordinating the activities of the NASA Communications Division (NASCOM

of the Goddard Space Flight Center, which provided the intercontinental circuits, th

local short-haul line carriers, and the communications supervisors at the DSSs.

All communications traffic between the DSSs and the NOCC/MCCC first passed throug

the CCT, where it was routed to its prescribed destination. This function, originally ca

ried out by established line-switching methods, would be replaced by more flexible an

reliable message-switching techniques by the end of the Viking Era. By that time als

new capabilities for automatic detection and correction of short line outages and da

block errors would ensure continuous and error free communications support for rea

time flight operations.

86

Uplink-Downlink: A History of the Deep Space Networ
NETWORK OPERATIONS

The Helios Mission

As the urgency of the NASA space program of the mid-1970s carried the DSN forwa

into the Viking Era of 1975–1977, it was not an American but a German spacecra

that vied with the NASA missions for DSN attention. 

Conceived in 1966 as a cooperative project between NASA and the Federal Repub

of Germany (West Germany), the Helios Mission would eventually consist of two sol

probes launched toward the Sun—one in each of calendar years 1974 and 1975—

achieve a perihelion distance (point of closest approach) from the Sun of approximat

ly 0.3 AU (Astronomical Unit; the mean distance between Earth and Sun, approximate

150,000,000 kilometers or 93,000,000 miles).

Each spacecraft would carry ten scientific experiments to perform field and particle mea

urements in the region between Earth and the Sun. The target perihelion distance 

0.3 AU was chosen because it bounded a previously unexplored region of interplan

tary space and was within the estimated limits of the high-temperature capability of th

solar cells necessary to generate power for the spacecraft. As viewed from Earth, th

Helios trajectory took the form shown in Figure 3-3. 

It would provide unique opportunities for high-value scientific observations during th

repeated periods of perihelion (closest approach), aphelion (farthest approach), and sol

conjunctions (spacecraft obscured by Sun).

The spacecraft carried two 20-watt S-band transponders, both of which operated on th

same uplink and downlink frequencies. The transponders provided a capability for cohe

ent or non-coherent operation, turnaround ranging, and ground command of the spacecra

The Helios spacecraft employed one telemetry channel to transmit both science an

engineering data back to Earth. Both data types were convolutionally encoded and mo

ulated on to a single 32.768-kilohertz subcarrier, which in turn was phase-modulat

onto the S-band downlink. The combined science and engineering information data ra

could be varied from 8 bits per second to 4,096 bits per second in steps of two.

Ground command capability was provided by two actively redundant receiver/comman

detector chains; one connected permanently to the low-gain (omni) antenna, the oth

to the medium-gain antenna system. Separate command subcarrier frequencies perm

8

The Viking Era: 1974–1978
ted ground control to select either chain, regardless of spacecraft orientation. The com

mand data rate was Manchester-coded 8 symbols/second, which phase-modulated eith

the 448- or the 512-hertz subcarrier.

The first Helios spacecraft (Helios 1) was launched on a Titan-Centaur launch vehic

from Cape Canaveral, Florida, on 10 December 1974.

On 15 March 1975, 96 days after launch, Helios 1 reached its first perihelion at 0.3

AU (see Figure 3-3). Although the perihelion was the focal point of scientific intere

88

Uplink-Downlink: A History of the Deep Space Networ

Figure 3-3. Heliocentric orbit of Helios 1.

REGION OF SOLAR

OCCULTATION

FIRST APHELION

190 DAYS AFTER 

LAUNCH

FIRST PERIHELION

96 DAYS AFTER 

LAUNCH

SECOND PERIHELION

288 DAYS AFTER 

LAUNCH

180

210

240

120

SUN

270

90

300

30

60

120

150

210

240

300

330

1.0 AU

0.8 

0.6

0.4

0.3

0.2

330

390 360

90

DEGREE

270

DEGREES
for the project, the period of 25 days about perihelion was also fascinating to inves

gators. During this period, the spacecraft would traverse hitherto unexplored regions 

the inner solar system and collect scientific data that would increase our understandin

of the Sun’s influence on Earth and its surroundings.

Planning and scheduling the supporting stations (DSS 12, 14, 42, 44, and 62) to cov

this event were enormously complicated by the conflicting requirements for DSN su

port generated by the Mariner 10 mission (then making its third Mercury Encount

on 16 March 1975) and support for Pioneer 11, which was completing encounter ope

ations at Jupiter at the same time. To further complicate the problem, the Viking an

the Pioneer Venus projects were also demanding attention for pre-launch testing an

training activities. Because of this situation, Helios was unable to obtain some of th

prime 64-meter antenna support and much of the redundant 26-meter station covera

it desired. Nevertheless, by a process of pass-by-pass negotiation, and a willingness b

all flight projects involved to adapt tracking schedules to real-time changes, the DS

commitment to provide continuous tracking coverage throughout this phase of the Heli

mission was largely satisfied.

Throughout 1975, the Helios 1 spacecraft continued along its predetermined path aroun

the Sun, as shown in Figure 3-3. Perihelion, aphelion, and superior and inferior co

junctions continued to afford unique opportunities for science data observations, whi

in turn led to special requirements for DSN support by the 64-meter stations when th

Sun-Earth-Probe (SEP) angle was small (less than 7 degrees).

Plans for launching a second Helios spacecraft in December 1975 were formally com

pleted by the project at a Joint Working Group meeting in Munich in May 1975. Th

second Helios mission (Helios 2) would closely parallel that of Helios 1 and provide th

scientists with three high-interest, perihelion crossings during the course of the missio

However, initial launch and early phases of the new mission would be controlled in 

markedly different manner.

The Helios 2 launch phase would be controlled from the German Space Operatio

Center (GSOC) at Oberpfaffenhofen near Munich rather than from the Mission Operatio

Control Center at JPL, as it was for Helios 1. This decision, which marked a significa

advance in the confidence and capability of the newly established German space agen

to manage deep space mission operations, would eventually create a resource of gre

assistance to NASA in general and the DSN in particular. However, a backup spacecra

operations team would be located at JPL during the critical launch period to deal wi

8

The Viking Era: 1974–1978
any unforeseen emergency. The DSN would continue to provide standard tracking st

tion support, subject to availability of resources, throughout the mission.

Realizing that it would be unable to meet all of the demands for tracking station su

port in 1976, the DSN managers had, in 1975, negotiated an agreement with th

Spaceflight Tracking and Data Network (STDN) for its stations in Goldstone and Madr

to provide a limited receiving-and-analog tape recording capability for the Helios 1 an

2 spacecraft telemetry signals. These tapes were to be shipped to the STDN station 

Merritt Island, Florida (MIL 71), where they would be converted to digital recording

which could then be replayed to JPL via the NASCOM communications circuits. A

JPL, the digital telemetry data were merged into the Helios Master Data Record an

delivered to the Helios Mission Control Center in Germany in the same manner us

for a normal DSN telemetry record.

Beginning in January 1976, this rather cumbersome operational arrangement suppor

ed Helios 1, while the DSN focused on the launch of Helios 2. Throughout 1976 an

1977, “STDN cross-support,” as it was called, was used extensively to recover Heli

scientific data that would otherwise have been lost due to the over-subscription of DS

tracking resources in those years.

The Helios 2 spacecraft was launched on 15 January 1976, with initial acquisition occu

ring over DSSs 42 and 44. Primary control of the Helios 2 postlaunch activities w

carried out by the GSOC with a backup team at JPL. The spacecraft successfully ca

ried out the maneuvers necessary to establish its correct orientation for the life of th

mission and began its long journey around the Sun. During its perihelion passage 

mid-April 1976, it would pass three million kilometers closer to the Sun than did Heli

1 (0.29 AU versus 0.31 AU). Helios 1 and 2 traveled similar trajectories, and the obse

vations from Helios 2 could be correlated with those of Helios 1 to improve the det

and precision of the data.

The primary mission for the Helios 2 spacecraft ended in May 1976 as the first sol

conjunction approached. Despite the degraded downlink as the SEP angle fell below 

degrees, the solar conjunction period continued to be of great interest to the Rad

Science Team. They continued to gather Faraday Rotation and Celestial Mechanics da

from the spacecraft downlink as the radio path from the spacecraft to the Earth approach

ever closer to the solar disk and eventually entered solar occultation. In this period (

small SEP angles), the sequential ranging technique of the Mu-2 ranging machine prov

superior to the standard DSN planetary ranging system in generating good ranging da

in the presence of increasing solar noise.

90

Uplink-Downlink: A History of the Deep Space Networ
In May 1976, the Helios project announced a plan to modify, by the end of the ye

the German Telecommand Station at Weilheim to include a telemetry data receivin

capability for Helios. The additional coverage afforded by a dedicated German statio

coupled with the spacecraft capability to store data for transmission during a later trac

ing pass, lessened the advantages of the cross-support mode with its attendant losses an

time delays. The Helios requirement for STDN cross-support was therefore withdraw

at the end of the Helios 2 prime mission.

The DSN managers decided, however, to continue engineering tests to evaluate the u

of a microwave link between a STDN and a DSN station for real-time telemetry pr

cessing and commanding.

Helios 1 and Helios 2 spacecraft, while in their extended mission phase, rated equal p

ority with Pioneer 10 and 11 for DSN support. With Viking preparations for the fir

landing on Mars approaching their climax, only limited DSN tracking support f

Helios could be expected. Unlike the JPL spacecraft whose lifetime depended critica

ly on a supply of inert gas to power the attitude stabilization systems, the Heli

spacecraft were spin-stabilized like the early Pioneers and not dependent on a limit

gas supply. They could therefore continue to orbit the Sun and return science data 

long as the uplink and downlink with the Earth tracking stations (DSN and Weilheim

remained operable.

Supported by the DSN at a low level of effort, the Helios mission continued to retu

a wealth of science data relative to the Sun and its environment until the mission w

terminated in 1985.

Long before that point was reached, however, the focus of DSN attention had shift

to other missions.

It was June 1976, and the Viking Mars Lander Mission was about to move into th

spotlight and demand the full resources of the DSN and a great deal of attention fro

the media.

The Viking Mission

Any way you looked at it, the Viking Mars Lander project was big. Big in concep

scale, price, success, and big in impact on the DSN.

9

The Viking Era: 1974–1978
Like the successful Lunar Orbiter project some years earlier, the Viking project w

managed for NASA by the Langley Research Center (LaRC) in Hampton, Virgini

The Project Manager was James S. Martin, Jr. However, JPL had two roles to pl

in the Viking project. One was to design and build the Orbiter that would carry th

Lander into Mars Orbit and the other was to provide the tracking and data acqu

sition support required by both Orbiters and both Landers, simultaneously. Langl

would provide the Lander. The launch and mission operations would be conducte

by a joint LaRC/JPL mission operations team led by a Mission Director appointe

by LaRC.

The concept was to deliver an instrumented space vehicle to Mars orbit from whe

it would be released to descend softly to a preselected landing site, there to searc

for signs of extraterrestrial life, and make in situ observations of the local surface fe

tures and weather. Two such vehicles would be built and launched in the 1975 launc

opportunity. The cost of the Landers and Orbiters was estimated at about $620 m

lion (1977),1 an enormous amount for a single project in the 1970s. The heav

combined Orbiter/Lander spacecraft weighed 3,500 kilograms and required the mo

powerful launch vehicle combination then available, the Titan/Centaur, to boost 

to the Red Planet.

Viking held the unique promise of finding an answer to a question that had ta

talized the thoughts of humans throughout the ages: “Does life, in any form, exi

anywhere outside our own planet Earth?” At that time, the science communit

although not unanimous in its opinion, held that the most likely candidate was th

planet Mars.

Viking was a very high profile mission which demanded, and expected to get, all of th

DSN resources that were available. It also demanded significant new capability that th

DSN did not have, but was requested to implement specifically for Viking. The hig

er levels of DSN management that had for so long been used to accommodating JP

missions, did not at first respond well to this off-lab method of doing business. Th

were not ready to accept requirements for support, particularly those requiring new deve

opments, with equanimity. They felt entitled to challenge the need for the stated suppo

conduct an independent ground/space telecom link trade-off analysis and evaluate alte

nate approaches. This was the very antithesis of the kind of response that the Vikin

Project Management Team could accept, and it took a long time and many harsh word

with appeals to higher authority, before the two sides found a workable solution. Pa

of the problem arose from the fact that the Viking Project Office was on the other si

of the country from California.

92

Uplink-Downlink: A History of the Deep Space Networ
DSN representatives became involved in negotiations for DSN services and resourc

far from their home office, with a project office that expected on-the-spot agre

ments. The Viking people could not understand why this was not always possibl

The reason lay in the difference between the single-minded management style of th

Viking Project Office, where everything was focused on and controlled by the pro

ect, and the Tracking and Data Acquisition Office at JPL, where the DSN was manag

somewhat along the lines of “the greatest good for the greatest number.” At th

stage, despite a plethora of formal NASA documentation, the DSN process for wor

ing with off-lab projects had not matured to the point where there was well establishe

procedure for negotiating and approving new flight project requests for DSN su

port and resources.

Eventually, the DSN office produced a large, new document that specified all of its cap

bilities and the technical details associated with them. It was titled the Deep Space Netwo

to Flight Project Interface Design Handbook and was assigned the number 810-5.2 In th

future, new flight projects seeking DSN support for their missions would be expect

to use this technical interface document as a “shopping list” to identify their requir

ments on the DSN for support. To a large extent, this avoided the difficult bargainin

experienced in the Viking negotiations.

The scientific background to Viking stemmed from the Mariner missions to Mars 

1964–65, 1969, and 1971–73. In 1965, Mariner 4 was the pioneering flight to Ma

providing a few television pictures of its cratered surface and defining the physic

parameters of its atmosphere in a fast flyby mission. In 1969, Mariners 6 and 7 co

ducted more extensive approach and flyby imaging, acquired spectral data o

atmospheric composition, and did initial thermal mapping. Mariner 9, placed in orb

about Mars in 1972, surveyed the entire surface at various image resolutions and pe

formed extensive spectral, thermal, and gravitational studies. A landing mission w

the next logical step.

The concept of the Viking project involved two Viking spacecraft, each consisting of a

Orbiter and a Lander, boosted by a Titan/Centaur launch Vehicle into a Mars traject

ry at the 1975 launch opportunity. On arrival at the planet, each spacecraft was to 

placed in orbit. Then, following a mapping survey and landing-site verification, th

Lander capsule was to separate from its Orbiter, and descend through a complex lan

ing sequence to the Mars surface. The configurations of the Viking Orbiter and Vikin

Lander are shown in Figure 3-4. Figure 3-5 depicts uplink/downlink telecommunic

tions among the DSN, the Viking Orbiter, and the Viking Lander on Mars.

9

The Viking Era: 1974–1978
Figure 3-4. Configurations of the Viking Orbiter (top) and Viking Lander (bottom).

94

Uplink-Downlink: A History of the Deep Space Networ

S-BAND HIGH-GAIN

ANTENNA (DIRECT)

MAGNIFYING MIRROR

RADAR ALTIMETER

ELECTRONICS No. 1

MAGNET AND CAMERA

TEST TARGET

SEISMOMETER

RADIO-ISOTOPE THERMOELECTRIC

GENERATOR POWER SOURCE (2)

(INSIDE COVER)

ULTRAHIGH FREQUENCY

ANTENNA (RELAY)

RADIO-ISOTOPE

THERMOELECTRIC GENERATOR

WIND COVER (2)

S-BAND LOW-GAIN ANTENNA

ROLL ENGINE (4)

TERMINAL DESCENT

PROPELLANT TANK (2)

TERMINAL DESCENT

LANDING RADAR

(UNDERSIDE OF LANDER STRUCTURE)

LEG No. 2

GAS CHROMATOGRAPH

MASS SPECTROMETER PROCESSOR

METEOROLOGY

BOOM ASSEMBLY

METEOROLOGY SENSORS

CAMERA (2)

(NONFUNCTIONING IN

LANDED CONFIGURATION)

RADIO-ISOTOPE

THERMOELECTRIC GENERATOR

COOLANT LINES

PROPULSION FILL AND

N2 MAKE UP LINES

TERMINAL DESCENT

ENGINE (3)

18 NOZZLE CONFIGURATION

LEG No. 3

MAGNETS

COLLECTOR HEAD

FURLABLE BOOM

X-RAY FLUORESCENCE FUNNEL

BIOLOGY PROCESSOR

ATTITUDE CONTROL

GAS JETS

HIGH GAIN ANTENNA

VIKING LANDER

SOLAR ENERGY CONTROLLER

SOLAR PANEL

PROPULSION

MODULE

LOW GAIN ANTENNA

CRUISE SUN SENSOR

AND SUN GATE ORBITER BUS
9

The Viking Era: 1974–1978

Figure 3-5. Viking Orbiter, Lander, Earth Telecommunications System. This diagram, by Ez

and Ezell, shows the uplink and downlink between the Deep Space Network and the Viking Orbite

the uplink and downlink between the Deep Space Network and the Lander on Mars, and th

uplink data relay from the Lander to the Orbiter.
Although the primary science investigations would be carried out by the Lander on th

Mars surface, a significant science return would be obtained from the experiments co

ducted by the Orbiter and by the Lander during its descent through the Mars atmospher

At its inception in the late 1960s, the Viking project was intended to be launched 

the 1973 opportunity, making use of the Mariner 69 and Mariner 71 Orbiter desig

and operations experience, and their data on the planet. Viking 73 would complete th

Mariner-Mars orderly sequence of planetary exploration by soft landing a package of sc

entific instruments on the surface of the planet. To increase mission reliability and scientif

scope, two launches were planned. Precise navigation data would be required to achie

the desired landing accuracy, and large quantities of scientific and engineering data we

to be telemetered from the two orbiting and two Lander craft. Preliminary Tracking an

Data System planning was undertaken on this basis. 

Construction of the 64-meter antenna subnet of the DSN was just then getting unde

way after a few years of successful operation of the initial advanced antenna system at DS

14 at Goldstone, California. A contractor had been selected to build and install the 6

meter antennas at the overseas sites in Australia and Spain, and these facilities were schedul

to be ready to support the 1973 Viking missions. In addition, during this period, oth

new elements of the Tracking and Data Acquisition (TDA) system destined for Vikin

support were being demonstrated, such as high-rate telemetry, high-power transmitte

and the Differenced Range versus Integrated Doppler (DRVID) navigation technique.

At the beginning of 1970, funding considerations created far-reaching changes in th

Viking project and resulted in an alteration of the flight schedule from a 1973 to 

1975 launch opportunity. The revised launch date permitted a more thorough asses

ment of the TDA support requirements and capabilities, and an increased level 

commitment from what would have been possible for a 1973 mission.

By the end of 1973, the planning phase was essentially complete. The design had mature

and key capabilities and interfaces had been defined. In addition, the network of 6

meter antennas was operational, and the implementation of new capabilities needed f

Viking had begun. Initial design compatibility testing with breadboard models of th

Orbiter and Lander radio systems had begun in the Compatibility Test Area 21 (CTA2

at JPL. Known as “DSN Compatibility Testing,” this practice had become standard b

1977 for all spacecraft with which the DSN was involved, and was indeed part of th

agreement with the flight projects seeking tracking and data acquisition support fro

the DSN. The DSN had established two compatibility test facilities, one at JPL call

Compatibility Test Area 21 (CTA 21), and the other on Merritt Island at Cape Canaver

96

Uplink-Downlink: A History of the Deep Space Networ
(MIL 71). Except for the actual large DSN antennas, both facilities were equipped wi

hardware and software representative of, and generally identical with, that which w

installed at the DSN tracking stations around the world. Radio frequency uplinks an

downlinks at S-band, X-band, and small (2-meter) calibrated antennas and radio fr

quency (RF) attenuators were used to accurately simulate the signal paths between th

inflight spacecraft antennas and Earth station antennas. Following these tests, simulat

spacecraft data were input to CTA 21 to verify the design of the end-to-end groun

data link, beginning with the radio frequency data from the spacecraft and ending wi

data displays in the Mission Control Center. In progressive stages, these simulated ope

ations were built to represent the maximum mission load conditions; system integratio

and data compatibility were demonstrated during mid-1974.

A succeeding series of ground data system tests, using actual tracking stations and te

models of the Viking Orbiter and Lander provided training for the personnel of th

Flight Operations System who would actually conduct the mission, as well as the DS

and Mission Control Center personnel who would support it.

Because there were to be two Viking launches close together, the DSN would be call

upon to track two Viking spacecraft en route to Mars simultaneously. When they reach

Mars, each spacecraft would separate into an Orbiter and a Lander, so that then fo

Viking spacecraft would be supported at various times by the DSN stations. Althoug

only one Lander at a time would require a direct link back to Earth, this multiple spac

craft task would refire all the tracking stations in the DSN to handle it.

One set of 26-meter stations was required to provide support for the launch and crui

period of both Vikings until limiting uplink and downlink conditions necessitated th

use of the large 64-meter stations. The second set of 26-meter stations was required 

back up the first set if necessary, and to take over some of the tracking load when th

Helios solar mission needed the services of the first set during its launch period later 

the year. All four uplinks and downlinks of the Viking Orbiters and Landers would u

the standard DSN S-band frequency channels, except that the Orbiters also carried X

band downlinks. These were intended to demonstrate the advantages of the higher frequen

X-band channels for deep space communications, an advance in technology that th

DSN proposed to introduce into the Network in the years ahead. It was expected th

the increase in DSN capability would be even greater than that which resulted from th

change to S-band several years before.

The DSN capabilities required to support the 1975 Viking Missions to Mars are show

in the following table.

9

The Viking Era: 1974–1978
Deep Space Station Capabilities for Viking (1975)

26-Meter Antenna Stations

Deep Space Stations (DSS) 11, 42, 61, 12, 44, and 62

One low-rate, plus one medium-rate telemetry data stream

S-band ranging, shared at DSS 11, 42, 43, 61, and 63

S-band Doppler at each station

One high-speed ground communications channel

Digital original data record with automatic total recall

Analog original data record with station replay

64-Meter Antenna Stations

Deep Space Stations (DSS) 14, 43, and 63

Single command uplink, 20 kilowatt prime, 100 kilowatt/400 kilowatt

backup

Up to six low-, medium-, and high-rate telemetry data streams

S- and X-band ranging

S- and X-band Doppler

One high-speed and one wideband ground communications channel

Digital original data record with automatic total recall

Analog original data record with station replay

S- and X-band occultation data, receive and record

S-band very long baseline interferometry data receive and record at DSS

14 and 42 only

Ground Communications Facility 

50 kilobit per second wideband channel DSS 14 to JPL (GCF Central

Communications Terminal)

27.6 kilobit per second wideband channel DSS 43 and 63 to JPL

4800 bits per second high-speed channels to/from all stations and JPL

Circuit performance monitoring and error detection

Network Operations Control Center 

Automatic total recall capability

Intermediate data record production

Network system performance monitoring, display, and data system

validation

Tracking performance monitoring

Network operations control

98

Uplink-Downlink: A History of the Deep Space Networ
Mars Planetary Radar (Goldstone)

X-band transmit and receive

Up to 400-kilowatt transmit power desired

Use of developmental (rather than operational) hardware and software 

Individual uplinks and downlinks, each with its own particular parameters and critic

data path, would present an operational challenge at every level to all elements of th

DSN. The complexity of the mission is reflected in the downlink telemetry capabiliti

of each of the two simultaneous Viking spacecraft (see the following two tables).

Viking Orbiter Telemetry Channels

Channel Data Type Data Rate Subcarrier 

(bits per second) (kilohertz)

Low Engineering 8 1/3 or 33 1/3 24

(uncoded)

High Science 1k, 2k, 4k, 8k, 16k 240

(block-coded, 32, 6)

Science 1k, 2k, 4k 240

(uncoded)

Viking Lander Telemetry Channels

Channel Data Type Data Rate Subcarrier 

(bits per second) (kilohertz)

Low Engineering 8 1/3 or 33 1/3 12

(uncoded)

High Science 1k, 2k, 4k, 8k, 16k 72

(block-coded, 32, 6)

Science 250, 500, 1000 72

(uncoded)

9

The Viking Era: 1974–1978
Four Vikings (two Orbiters and two Landers), together with the other inflight m

sions being supported at the same time, were about to stress the DSN multimissio

concept to its limits. At the outset, it was recognized by both the DSN and the pro

ect that the most severe operational challenge lay in the successful establishment an

manipulation of multiple communication and data links with the four spacecraft, tw

Orbiters and two Landers. A very extensive series of engineering “compatibility” tes

were planned to demonstrate the integrity of the uplinks and downlinks. Realistic m

sion sequences were simulated to train the operations personnel, and comprehensi

exercises of increasing complexity were used to measure the proficiency of the com

bined DSN and Viking flight operations teams. At the same time, similar test an

training exercises were being carried out within the huge organization associated wi

the actual Titan-Centaur launch itself.

Eventually, all the prelaunch readiness criteria were met, the final launch readine

review was held and the approval for launch was given, and the countdown bega

Unfortunately, both launches were delayed by technical problems that could not 

corrected on the launch pad and that necessitated removal of the spacecraft from th

Titan-Centaur launch vehicle. Reassembly and testing further delayed the liftoff. Final

Viking 1 was launched on 20 August, followed by Viking 2 on 9 September 197

Both launch vehicles performed perfectly to inject their payloads into Mars traject

ries with arrival times at Mars of 19 June and 7 August 1976, respectively.

In both cases, the Australian 26-meter stations performed the initial acquisition sequenc

precisely as planned—a tribute to the careful planning and intensive preflight testin

and personnel training that preceded it. Both Viking spacecraft survived the stressf

launch conditions without incident, and the “cruise” phase of the Viking mission 

Mars began.

During the next few months, each spacecraft would move continuously along its ind

vidual trajectory, gradually crossing the region of deep space between the injectio

point on the orbit of Earth (around the Sun) to its final injection point on the orb

of Mars (around the Sun). It would be performing maneuvers to correct its traject

ry for small errors, carrying out scientific experiments in deep space, checking an

calibrating the science instruments that the Orbiter would use to make observatio

from Mars orbit, and checking the condition of the all important Lander and th

instruments it would use to carry out experiments on the Mars surface.

The DSN would maintain continuous uplinks and downlinks to communicate wi

both Vikings, generate radiometric tracking data for spacecraft navigation purpose

100

Uplink-Downlink: A History of the Deep Space Networ
and evaluate the performance of the new X-band downlink. The DSN would also 

completing implementation of the new and extended capabilities required for the Ma

“Orbiter operations” phase and “Lander operations” phase. Expansion was required 

almost every area. The quality of the Doppler data used for spacecraft navigation ha

to be improved, and the data rates for the Orbiter telemetry had to be increased, 

did the capability of the tape recorders used to record it at the Complexes. New har

ware and software was needed to provide monitor and control functions for the ne

equipment. Earlier, the Viking project determined that in the event of adverse lan

ing attitude conditions, the standard DSN 20-kilowatt transmitter power would n

be sufficient to uplink commands to the lander to work around the situation. 

demanded the newly installed 100-kilowatt transmitters which had not been prove

for support of regular network operations, let alone critical support of the type su

gested. Furthermore, because of greatly increased emphasis on the evaluation of alterna

Mars landing sites, a request was made for the assistance of an experimental 400-kil

watt X-band transmitter that was being used at Goldstone for the study of planeta

surfaces using radar techniques. At one stage, over 400 major change items were wor

ing their way through the DSN change control system to meet the Viking schedul

Engineering and operations staff were augmented to cope with the work and ong

ing operations-everyone seemed to be working on Viking.

Nevertheless, the changes and additions were made and tested, and the DSN was read

when the first Viking arrived at Mars.

On 19 June 1976, Viking mission controllers started the 28-minute retro-engine bu

that slowed Viking 1 down from its approach speed of 14,400 kilometers per hour 

10,400 kilometers per hour to allow it to be captured into Mars orbit. Later, aft

evaluation of the navigation data, the retro-engine was burned again, this time f

132 seconds, to adjust the orbit slightly to bring it over the prime landing site. Th

spacecraft was now in a 24.6-hour orbit, corresponding to the length of a Martia

day. The landing site would be viewed by the Orbiter on each subsequent revolutio

near the lowest part of the orbit. With the completion of orbit insertion and trim

the “cruise” phase of the Viking 1 mission had been completed.

In the days that followed, the analysis team evaluated the Orbiter pictures and th

Goldstone radar data to the last possible detail to arrive at consensus regarding th

best (or rather, least risky) place to land consistent with meeting the principal scien

objectives of the Mission. The range of possible landing sites was constrained not on

by the surface features, which could pose a threat to the safety of the lander as 

10

The Viking Era: 1974–1978
descended, but also by the need for a biologically promising area, which would 

indicated by the possible presence of water in some form.

The science teams searched long and hard for an agreement, and finally selected “alph

site” in the large central basin, at 22.5 degrees north latitude and 47.5 degrees west lo

gitude. Once the decision to land had been made, the necessary planning follow

rapidly. At 10:30 p.m. on 19 July, after calling for readiness reports from each of th

major elements of the project, the project manager announced the “Go” for separatio

of the lander from the Orbiter. The separation and descent sequences were initiated an

all events followed exactly as planned.

With the Orbiter low on its radio horizon, DSS 43 transmitted the Lander separatio

“Go” command to the Orbiter at 07:47:18. The Orbiter released the Lander about a

hour later, and began sending relay data from the Lander as it descended through th

Mars atmosphere to the surface. By 09:20, the Orbiter was beginning to set over th

Australian Complex, and control was passed from Canberra to Madrid where DSS 6

continued to receive the Lander descent data and forward it to JPL. Back in the Missio

Control Center at JPL, the Viking flight team anxiously watched the Lander telemet

data as the tension mounted. The Lander Team Leader called off the radar-altimet

readings and the critical events as they were executed in perfect sequence by the Land

Finally, at 05:11:43 Greenwich Mean Time (GMT), came the announcement, “We ha

touchdown.” Knowing that several critical housekeeping chores remained to be carri

out before the first picture taking could begin, the jubilation in the Mission Contr

areas was rather restrained. The Lander appeared to be in a nearly nominal attitud

positioned in a stable, level landed configuration. The shutdown and reconfiguratio

tasks were accomplished without incident, and the first real-time imaging sequence bega

The first picture (Figure 3-6) appeared on the monitors in Mission Control half an ho

later. It showed the circular footpad at the end of one of the three legs of the Land

neatly settled on the Martian soil. A few light-colored deeply pitted rocks lay in th

foreground.

A second picture (Figure 3-7) soon followed. It showed a 300-degree panorama of wh

appeared to be a sandy plain covered with rocks of various sizes.

The quality of the first pictures from the surface of Mars astonished the flight team, th

hundreds of guests gathered at JPL to observe the event, and the national television aud

ence that saw the pictures a short while later. These images were humankind’s first close-u

view of Mars. Congratulations from the project manager, the NASA Administrator, an

President Gerald Ford soon followed.

102

Uplink-Downlink: A History of the Deep Space Networ
With one Lander on the surface, one Orbiter in orbit, and the Viking 2 spacecraft ra

idly approaching its Mars orbit insertion point, the tempo of activity by the Vikin

flight team and in the DSN reached an unprecedented level. While some of the sc

entists were anxious to initiate the biology experiments related to the search for lif

others were faced with the task of selecting the second landing site. The spacecraft co

10

The Viking Era: 1974–1978

Figure 3-6. First Viking close-up picture of Mars surface. Viking Lander 1 took this close-up ph

tograph of the Martian surface just minutes after its successful touchdown on the Plain of Chryse 

20 July 1976. The center of the image is about 1.4 meters (5 feet) from the spacecraft camera. 

portion of the Lander footpad is visible in the lower right corner of the picture. The spacecraft co

tinued to observe surface features and carry out numerous other scientific experiments on the Marti

surface and environment until it ceased operating on 13 November 1983.

Figure 3-7. First panoramic picture of the surface of Mars.
trollers were involved with managing Viking 2, then in Mars orbit, as well as opera

ing Lander 1 and Orbiter 1. The DSN was doing its best to keep up with the deman

for more and more tracking time, as well as with the avalanche of data from bo

Orbiters, now running at 16,000 bits per second.

Responding to commands from its controllers at JPL, Lander 1 scooped up the fir

samples of Mars soil on 28 July and carefully transferred them to its various scien

instruments for biological, chemical, and molecular analyses.

By mid-August, Orbiter 1 had been in orbit around Mars for 55 days making a com

prehensive photo reconnaissance of possible landing sites for Lander 2. Lander 1 ha

been on the surface for 24 days obtaining striking pictures of the Martian landscap

and making continuous observations of Mars weather, surface features, and comp

sition, as well as analysis of the Mars atmosphere. For the first time, the DSN cou

establish a direct radio link between its antennas on Earth and an antenna on th

surface of another planet. Radio scientists used this capability as a highly preci

instrument to refine existing knowledge about the physical properties of Mars an

its atmosphere.

The data from the Lander 1 biology instrument, which was analyzing the Martian so

samples, was indicating the possibility of a biological response. However, other possib

causes of the response were being considered and tested as the experiment continue

It was still much too soon to reach any conclusions regarding the existence (or none

istence) of Martian life.

Late in August 1976, a decision was made regarding the second landing site. Lander 

would land in the eastern end of the Plains of Utopia at latitude 48 degrees north, lo

gitude 226 degrees west. Once that decision was made, events followed a similar cour

to those of Viking 1. Touchdown would occur on 3 September. At 9 a.m. that day, th

Viking Flight team met for the “Go/no go” for separation decision. All systems repor

ed “Go” for separation. The commands were sent from DSS 14, and the separatio

sequence began to execute.

But there were some heart stopping moments to come before Viking mission contr

would know that Lander 2 was on the surface. Shortly after separation, Orbiter 2 ceas

sending the telemetry data it was relaying from the descending Lander. Swift action b

the spacecraft controllers at Mission Control and the station controllers at Goldston

determined that the spacecraft attitude stabilization system, on which it depended 

104

Uplink-Downlink: A History of the Deep Space Networ
keep its main antenna pointed toward Earth, had failed. Without the main antenna, th

Orbiter would not be able to transmit the Lander images to Earth.

In anticipation of such an eventuality, the Orbiter had been programmed to switch ov

to a small backup antenna and begin sending basic engineering data to aid in tro

bleshooting. Immediately, commands were sent to turn on the Orbiter tape recorder 

that the pictures from the Lander would be saved while the engineers figured out ho

to reestablish the main Orbiter to Earth radio link.

Using the downlink from the small backup antenna on the Orbiter to transmit a st

field map for reference, the spacecraft was commanded to slowly roll back to its orig

nal position and lock on to the celestial reference star, Vega. The main antenna w

activated, and to the great relief of all concerned, the downlink signal returned to no

mal. All subsequent sequences were executed as planned, and the first pictures fro

Lander 2 were received early in the morning of 4 September, nine hours later than ori

inally scheduled.

The first two pictures of the Utopia site were essentially similar to those taken by Land

1 in Planitia six weeks earlier. The first showed a footpad slightly embedded in sand

material with some debris flung around from the exhaust of the Lander retro-engin

The second picture revealed a barren rock-strewn plain, somewhat less rocky than th

corresponding picture from Lander 1. Following the landing, the science instrumen

began to gather data to complement the similar observations being made by Lander 

at Planitia.

For the next two months planetary operations continued at a furious pace. The flig

teams and DSN personnel and resources were fully extended. Problems arose, and we

corrected. Failures occurred and were worked around or backup systems were activate

Some data were lost, but very little. A few mistakes were made, but none which harm

any of the four active spacecraft. Within the Network, new operational procedures we

developed to overcome the difficulties of working with multiple spacecraft simultan

ously, and the multimission hardware and software held up to its arduous task of runnin

continuously at top speed.

Although the other experiments delivered a wealth of fascinating new scientific da

about Mars, the biology experiments continued to provide inconclusive results.

On 16 November 1976, the primary scientific objectives of the Viking Mission to Ma

had been achieved and, as planned, the “Prime Mission” was declared complete.

10

The Viking Era: 1974–1978
The scientific community began the task of analyzing the new Mars data and pu

lishing findings in science journals around the world. The findings of the biolo

experiment and its potential to reveal the presence of some form of life on Mars ge

erated particular public interest. The investigators needed to exercise extreme cautio

in reaching a conclusion on these results. One of the investigators told a press confe

ence, “Nobody wants to be wrong on a question as important as that of life on Mars

Efforts to explain the inconclusive results of the biology experiments continued, an

hopes of a nice crisp answer faded. An enormous amount of scientific debate ensu

over the following years, but eventually it was conceded that the three biology expe

iments did not provide conclusive evidence for the presence of living organisms o

Mars. Neither did it rule out the possibility. A NASA spokesperson declared, “No clea

unambiguous evidence of life was detected in the soil near the landing sites.” An

added, “The question of life on Mars, according to the Viking biologists, remains a

open one.” So the question remained unanswered.

Although the Prime Mission had officially ended, NASA decided to extend Mars pla

etary operations with the four active spacecraft for 18 months. By that same tim

interest and activity gradually moved to the events surrounding the rapidly approac

ing solar conjunction, the period of time when Mars moves behind the Sun as view

from Earth. Radio scientists would observe changes to the S-band and X-band dow

links as they slowly became intercepted by the solar disk. These effects would be interpret

to yield new information about the structure and composition of the solar corona an

the solar wind.

As Mars, with its four attendant spacecraft emerged from behind the Sun in late Novemb

1976, the spacecraft-to-Earth telecommunications links began to return to normal, m

sion operations activity increased, and the Viking “extended mission” began.

No one realized it at the time, but the Viking mission would continue in various form

for the next six years. Although the Landers were designed to operate for three mont

in the Prime Mission, one of them, Lander 1 would remain active until its last conta

with DSS 14 in mid-November 1982. The two Orbiters eventually depleted their at

tude stabilization gas supply and, without their antennas pointed toward Earth, we

unable to maintain an uplink or downlink. Lander 2 ceased operation in February 198

when its battery failed.

The extension of the Viking mission into 1977 continued to place heavy demands o

the DSN, not only because of the addition of radio science investigations to the orig

nal science experiments (except for biology, which had been completed in the Prim

106

Uplink-Downlink: A History of the Deep Space Networ
Mission), but also because the DSN was now engaged in replacing all its obsolete SD

computers with new MODCOMP minicomputers. Each of the nine tracking station

in turn, would have its old telemetry and command processors replaced with new machin

and software, and then be requalified to resume inflight support. It would be called th

Mark-III Data System (MDS) upgrade, and was to be accomplished without impact 

any of the inflight missions, including Viking (then running at its peak).

It was under these difficult circumstances that the focus of DSN attention moved 

another new flight project that would extend the capability of the DSN uplinks an

downlinks to even further limits. This new flight project was called Voyager.

The Voyager Mission

In its time, the Voyager project was one of the most ambitious planetary missions ev

undertaken. Voyager 1, which would encounter Jupiter in March 1979, was to inves

gate the planet and its large satellites; later, it would explore Saturn, its rings, and sever

of its satellites. Voyager 2 would arrive at Jupiter in July 1979. This spacecraft wou

also examine Jupiter and Saturn and their satellites, then it would be hurled on towa

an encounter with Uranus, which it would reach seven years later, in 1986. En rou

to these encounters, both spacecraft would make measurements of the interplaneta

medium and its interactions with the solar wind.4

10

The Viking Era: 1974–1978

Figure 3-8. Voyager trajectories to Jupiter, Saturn, and Uranus.

Jupiter

8/20/77

Jupiter

3/5/79

Each Voyager spacecraft follows a billion-kilometer path to

Jupter. Except for minor thruster firings to achieve small

trajectory corrections, each Voyager coasts from Earth to

Jupiter, guided by the gravitational pull of the Sun. At

Jupiter, the powerful tug of the giant planet deflects the

spacecraft and speeds them up, imparting an extra kick to

send them on their way toward Saturn.

Jupiter

7/9/79

Saturn

8/20/77

Saturn

11/13/80

Saturn

8/27/81

Uranus

8/20/77

Uranus

1/30/86

Earth

8/20/77

Earth

9/1/77 Mars

8/20/77

Sun

JupiterSaturnUranus

Voyager 1

Voyager 2
Except for minor adjustments to the trajectories made by the spacecraft thrusters, th

spacecraft would initially coast from Earth to Jupiter, guided by the powerful gravit

tional pull of the Sun. At Jupiter, the gravitational force of the planet itself would 

used to redirect the spacecraft toward Saturn.

Due to a problem that required the removal of Voyager 1 from the launch pad for repai

Voyager 2 was launched first. The launch from Cape Canaveral, Florida, in August 197

utilized the most powerful launch vehicle then available, the mighty Titan/Centaur. Voyag

1, launched sixteen days later on 5 September, on a shorter, faster trajectory, soon ove

took Voyager 2 and eventually reached Jupiter four months earlier than Voyager 2. 

To inject these heavy spacecraft into an Earth escape trajectory to Jupiter would requi

a five-stage rocket-motor burn sequence, two burns of the Titan, two burns of th

Centaur and a final single burn of the solid rocket motor in the spacecraft’s own propu

sion module. All these complex events were executed flawlessly on both occasions. Six

minutes after liftoff, the Voyager spacecraft were free of the influence of Earth’s gravi

coasting on their way to Jupiter at a speed of more than 10 kilometers per second.

The first DSN involvement with the Voyager spacecraft had taken place in the early mont

of 1977 when the spacecraft uplinks and downlinks had been subjected to a rigorous seri

of radio “compatibility” tests to ensure that spacecraft and DSN would be able to com

municate without problems after launch. For the Voyager tests, CTA 21 at JPL and M

71 at Cape Canaveral were each configured to simulate a 64-meter antenna station, an

each included both Block-III and Block-IV Receiver-Exciter Subsystems and the new MD

for telemetry, command, and radiometric data. The early tests at CTA 21 in March an

April were run with the spacecraft in the space simulator at JPL and established the vali

ity of the radio system design as represented by the spacecraft components being teste

The tests with the actual flight configuration spacecraft took place at MIL-71 in July an

August at Cape Canaveral. This was the last chance before launch to confirm beyond 

reasonable doubt that the Voyager-to-DSN uplink and downlink would function in spa

“as designed.” Both spacecraft passed the tests without reservation.

Sixty minutes after liftoff, separated from the Centaur and beginning its long jou

ney to Jupiter, Voyager 2 approached its second involvement with the DSN “initi

acquisition.”

“Initial acquisition” is the term used by the DSN to describe the chain of events th

take place at the first tracking station to observe, lock onto, and track the downlink si

nal after the spacecraft has separated from the launch vehicle and leaves Earth orbit 

108

Uplink-Downlink: A History of the Deep Space Networ
begin its planetary trajectory. A successful, two-way, initial acquisition is crucial to th

safety of the spacecraft and subsequent mission events. When completed, the data 

provides gives the mission controllers knowledge of the spacecraft condition via telem

try, the ability to control the spacecraft via the command uplink, and the capability 

determine the spacecraft orbit from the Doppler radiometric data generated by the DS

from the interaction of the coherent uplink and downlink.

Based on long experience of many launches of different spacecraft and different laun

vehicles, the DSN had refined the initial acquisition procedures by the time of th

Voyager launches to the point where the probability of success was related to two ma

factors. The first of these, dispersion errors in the powered flight part of the laun

sequence, affects exactly where and when the spacecraft will rise at the first viewing st

tion and, therefore, whether or not it will rise within the beamwidth of the DSN antenn

set to the predicted pointing angles. The second factor is the uncertainty in the pr

dicted downlink frequency at the time the spacecraft appears above the radio horizo

of the first acquiring station. This determines whether the spacecraft downlink will appe

in the bandwidth of the DSN receiver set to the predicted downlink frequency. Tim

is of the essence. Because all the uncertainties grow with time, the longer it takes 

acquire the spacecraft, the more difficult it becomes to accomplish.

When a spacecraft first appears over the radio horizon, its angular movement across th

sky is too great for the large 64-meter antennas to track. For this reason, the spacecra

is first acquired by the smaller, more agile, wide-beam 26-meter antenna. Much lat

when the trajectory has been well established and more accurate predicts become ava

able, the spacecraft can be transferred to the large 64-meter antenna. To further increa

the 26-meter antenna’s ability to view the spacecraft in the event of significant traject

ry dispersions, a small, wide-beam acquisition antenna is attached to the outer edge 

the 26-meter antenna and fed to a separate receiving and display device. Station ope

ators can use the acquisition antenna data to help point the 26-meter antenna to “lo

on” to the rapidly moving spacecraft.

The designated initial acquisition station for Voyager 2 was DSS 12 at Goldstone. Th

station had been configured according to the “Initial Acquisition Plan,” the necessa

prediction data for antenna pointing angles and rates had been loaded into the ante

na pointing system (APS) and the receiver frequencies and Doppler offsets had bee

updated based on the latest spacecraft frequencies measured just before liftoff. Simil

preparations had been made on board the NASA tracking ship Vanguard, which was o

station in the Indian Ocean, and the Goddard STDN tracking stations on Guam, Kwajalei

and Hawaii.

10

The Viking Era: 1974–1978
All of the Titan and Centaur powered flight events observed by the downrange trac

ing stations appeared to be “nominal.” About sixty minutes after liftoff, the spacecra

separated from the Centaur, burned its propulsion module engine for 45 seconds, an

was finally injected into a direct orbit for Jupiter. Within the next several minutes th

spacecraft carried out several pre-programmed maneuvers. After turning to point the ro

axis toward Earth, the science and RTG booms were deployed, and the spent propu

sion module was jettisoned. Then, with its S-band downlink transmitter turned “o

and its low-gain wide-beamwidth antenna pointed to Earth, it moved rapidly away fro

Earth orbit, passing high across the Indian and Pacific oceans toward the west coast 

the United States. In rapid succession, each of the antennas on Vanguard, Guam, Kwajalei

and Hawaii briefly acquired the downlink signal as the spacecraft rapidly passed throug

their field of view.

Finally, approximately 1 hour 14 minutes after launch, the spacecraft signal appeared 

the acquisition receiver at DSS 12. The receiver was immediately “locked up one-wa

on the spacecraft signal and the 26-meter antenna put into the auto-track mode. A fe

minutes later, the DSS 12 transmitter was turned “on” and the uplink frequency swe

across the spacecraft receiver rest frequency. Immediately, the spacecraft receiver lock

up on the DSS transmitter signal and, after a small readjustment of the downlink fr

quency, the DSS established two-way acquisition of Voyager for the first time.

Once the first tracking station had established an uplink and downlink with the Voyag

spacecraft, the telemetry, command, and radiometric data capabilities of the DSN becam

available to the Voyager Mission controllers. As the spacecraft continued to move aw

from Earth, its apparent eastward motion slowed and eventually reversed to the norm

westerly motion as Earth rotated beneath it. A few hours later, Voyager set at Goldston

and the spacecraft was transferred to the Canberra stations without incident. DSN su

port for Voyager had begun.

The powered flight and initial acquisition sequences for the Voyager 1 launch o

5 September 1977, followed essentially the same pattern of events as described abo

for Voyager 2, so that by early September 1977, the DSN had two additional planeta

spacecraft to deal with, both of them bound for Jupiter.

DSN support on the 26-meter Network for both Voyagers 1 and 2 during the last qua

ter of 1977 was fairly routine. The priority enjoyed by the project at that time was n

curtailed by scheduling conflicts with other inflight missions. The mission controllers we

involved with trajectory correction maneuvers, optical navigation imaging, analysis of spac

craft problems, and the calibration of various science instruments (the High-Gain Antenn

110

Uplink-Downlink: A History of the Deep Space Networ
and the S- and X-band communication links. During this time, the telemetry data ra

was running at 2,560 bits per second, and both spacecraft were operating well.

In November 1977, both spacecraft crossed the orbit of Mars to begin a nine-mon

crossing of the asteroid belt. By the end of the year on 15 December 1977, both spac

craft were more than 1 AU from Earth, with Voyager 1 having overtaken Voyager 

One-way radio communication time was 9 minutes 49 seconds for Voyager 1, and 

minutes 40 seconds for Voyager 2. Voyager 1 continued to increase its lead and wou

arrive at Jupiter in March 1979, four months ahead of Voyager 2.

In 1978, routine cruise operations continued normally on both spacecraft until ear

April. In the course of switching from primary to backup receivers on 5 April, it w

discovered that the backup receiver in Voyager 2 had developed a fault in its carrier trac

ing loop. Analysis by the project and DSN telecommunications engineers determin

that a capacitor in the receiver carrier tracking loop had probably shorted. Howev

soon after switching back to the prime receiver, it was found that it also had develop

a fault that proved to be permanent in nature. Since the spacecraft was unable to recei

commands from Earth on the now-permanently failed primary receiver, intense effor

were made by the DSN to develop a strategy that would permit commanding the spac

craft using the partially disabled secondary receiver, despite its failed tracking loop.5

The carrier tracking loop enables the spacecraft receiver to follow changes in the uplin

carrier frequency caused by the relative movement of the ground transmitter as Ear

rotates. This is the radio telecommunications equivalent of the well known Doppl

effect, and knowledge of its precise value is an essential element in the technique 

spacecraft interplanetary navigation. When no uplink is present, the spacecraft receiv

remains active at a frequency called its “rest frequency.” To activate an uplink and sen

commands, the uplink transmission must first be tuned to this rest frequency, after whi

the spacecraft receiver tracking loop will lock-on and follow the uplink frequency chang

due to Doppler throughout the tracking period.

The strategy that finally evolved from these efforts, to compensate for the inoperati

tracking loop, required the DSN to slowly change the transmitter uplink frequency du

ing a spacecraft tracking period in such a way that the frequency changes due to Doppl

as seen by the spacecraft receiver, would be cancelled out. The receiver could then lo

on to the DSN uplink at its rest frequency. No tracking loop action would be nece

sary and commands would be received by the spacecraft in the normal way.

11

The Viking Era: 1974–1978
On 13 April, the Voyager 2 recovery sequence, which was based on this strategy, w

initiated by DSS 63. In less than an hour it was confirmed that the first comman

had been received by the spacecraft receiver. Spacecraft controllers immediately sent 

large sequence of commands to suspend all but essential spacecraft activity; these com

mands would minimize any risk of losing the vital uplink while they set about evaluatin

the spacecraft condition and determining how to deal with it in the future.

Throughout the emergency, Voyager 2 had been tracked continuously by the 64-met

antennas with the cooperation of the Viking, Pioneer, and Helios projects, which we

also dependent on those antennas for their mission support. Only the 64-meter ante

nas could receive the low-power S-band signals that Voyager 2 had been transmittin

when the emergency occurred. As soon as possible, commands were sent to turn the 

band transmitter to high power so that the spacecraft could be tracked by the 26-met

antennas, thus relieving the pressure for 64-meter antenna support.

The Voyager 2 emergency placed an additional burden on the DSN operations organ

zation in terms of planning, tracking analysis, and real-time operations. It occurred durin

a period when there was a large number of very significant changes in progress throug

out the Network. These changes were associated with the MDS implementation, discuss

in more detail later. Suffice it to say here that in 1978 new telemetry, command, trac

ing, radio science, and data delivery systems were installed at all sites. DSS 12 w

withdrawn from operations and upgraded from a 26-meter, S-band station to a 34-met

S- and X-band station.

Apart from the actual installation and testing, all of these changes necessitated new pr

cedures and retraining of the Network operating personnel, while maintaining a hig

level of support for all of the inflight projects. Nevertheless, by using innovative oper

tional procedures to economize on station preparation time, and detailed negotiatio

and scheduling of the available resources, the DSN was able to maintain satisfacto

tracking and data acquisition support for all ten interplanetary missions in 1978.

Over the next few months, the Tracking-Loop-Capacitor (TLC) tuning sequence w

greatly refined and would eventually become a routine feature of DSN operational su

port for Voyager 2.

As a result of this timely recovery action, the Voyager 2 mission was able to resum

throughout 1978 with the high expectation of achieving all of its Jupiter missio

objectives.

112

Uplink-Downlink: A History of the Deep Space Networ
Both spacecraft continued to move through the 1978 cruise phase of the mission wit

out incident. Voyager support in the last few months of 1978 was reduced somewh

to allow the DSN to divert resources to support the Pioneer Venus and Multiprobe m

sions. Voyager 1 emerged from its crossing of the Asteroid belt in September follow

in October by Voyager 2. No events of any significance were reported. By the end 

the year, the project attention was focused on a new phase of the mission, due to beg

on 4 January 1979. It was called the “Observatory Phase” and would be the prelude 

the Jupiter encounters.

Pioneers 6–11

Since the start of the second-generation Pioneer program beginning with Pioneer 6 

1965, the DSN had introduced many modifications toward improving the thresho

capability of the Network for Pioneer telemetry support. Seven 26-meter stations we

equipped with improved masers, more efficient microwave equipment, linear antenn

polarizers, 3-Hertz receiver carrier tracking loops, advanced demodulation hardware, an

sequential decoding software (for support of Pioneer 9). By 1969, these systematic improv

ments had resulted in an extension of the Pioneer telemetry threshold on the 26-met

antennas from 0.4 AU (1965) to 1.5 AU (1969).6 The availability of the 64-meter st

tions increased the telecommunications link margins for the Pioneers so much that th

continued to be a significant presence in the DSN mission set throughout the Vikin

Era (Figure 3-1).

The Pioneer 10 and 11 missions to Jupiter were designed to investigate the interplan

tary medium beyond the orbit of Mars, the asteroid belt, and the near-Jupit

environment, hitherto unexplored regions of interplanetary space at that time. The spac

craft incorporated many technological advances over those in the interplanetary Pionee

6–9, although the design philosophy was the same and the same design team (NASA

Ames Research Center and TRW Systems) developed and built the spacecraft.7 Th

spacecraft were launched in 1972 and 1973, respectively, to solar system escape traje

tories. Pioneer 10 went on to become the first spacecraft ever to penetrate the astero

belt and, in December 1973, to obtain close-up images of Jupiter. Pioneer 11 reach

Jupiter one year later and was successfully retargeted for an encounter with Saturn 

September 1979.

The DSN supported both flights with the 26- and 64-meter stations, but there we

serious conflicts with the overlapping Mariner 10 mission to Mercury and Venus, du

ing 1973 and 1974, and the Viking requirements for prelaunch test time, and for Ma

radar observations from DSS 14 at Goldstone in 1975.

11

The Viking Era: 1974–1978
In March 1976, the Pioneer project was estimating a useful spacecraft life to 1983 f

Pioneer 10.

8 With the then-existing 64-meter station, the downlink telecommunicatio

limit at minimum bit rate (16 bits per second) would be reached in mid-1980 at 

range of about 22 AU, which is 2 AU beyond the orbit of Uranus.

Pioneer was already pushing the outer limits of long range deep space communicatio

links, but there was a strong motivation to push the uplinks and downlinks even fu

ther, hopefully to the point of matching the projected end of useful spacecraft lif

Downlink performance improvements were also of interest for the Pioneer 11 Satu

Encounter, where the highest data rate possible was desired to maximize the imagin

science data return. The predicted downlink telecommunications performance for Pionee

10 and 11 with both 26- and 64-meter antennas is shown in Figure 3-9.

At the time, there were a number of possibilities for improving the existing downlink pe

formance of the DSN antennas; these are listed in the table below. The table also gives t

factor by which the resulting telecommunications downlink margin would be increased (

decibels) and the multiplying factor by which the maximum range would be increased.

Possible Downlink Performance Improvements for Pioneers 10 and 11

Downlink 

Margin Increase Range Increase

Item Improvement (decibel) Factor

(1) Reduce receiver tracking 1.0 1.12

loop (BW = 3 Hertz)

(2) Improved low-noise 0.7 1.09

feed-cone (18.5 kelvin)

(3) Reshape the 64-meter 0.5 1.06

subreflector

(4) Increase 64-meter antenna 0.8 1.10

diameter to 70 meters

With the 1976 configuration of the 64-meter antenna, Pioneer 10 would reach the lim

of its telecommunications downlink at about 22 AU in mid-1980. This limit could 

extended to 24.6 AU, which the spacecraft would reach in early 1981, by using the 

Hertz receiver tracking loop bandwidth then available in the new Block IV receive

The improved S-band feed-cone would reduce the downlink system noise temperatu

114

Uplink-Downlink: A History of the Deep Space Networ
11

The Viking Era: 1974–1978

Figure 3-9. Downlink performance estimates for Pioneers 10 and 11.

PN-10 SUPERIORCONJUNCTIONJUNE 1978

PN-10 URANUSRANGE

PN-10 SUPERIORCONJUNCTIONJUNE 1979

PN-11 SUPERIORCONJUNCTIONSEPTEMBER 1979

PN-11 SUPERIORCONJUNCTIONSEPTEMBER 1978

PN-11 SATURNENCOUNTER

PN-11 SUPERIORCONJUNCTIONAUGUST 1977

PN-11 SUPERIORCONJUNCTION7 JUNE 1976

PIONEER 11

PN-10 SUPERIORCONJUNCTION25 APRIL 1976

PN-10 SUPERIORCONJUNCTIONMAY 1977

PN-10 SATURNRANGE

16

-170-169-168-167-166-165-164-163-162-161-160-159-158-157-156-155

32

64

128

256

512

1024

2048

1024

2048

RECEIVED CARRIER POWER AT 64-m ANTENNA DSS, dBmW

ROUND-TRIP LIGHT TIME, min256 512

350300250200150100500

-163-162-161-160-159-158-157-156-155-154-153-152-151-150-149-148

128

16 32

64

222120191817161514131211109876543210

22212019181716151413121110

9876543210

PIONEER 10

26-m ANTENNATELEMETRY BITRATES, bits/s

J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J ASOND J F M A M J J A S O ND J F M A M J J A S O N D

1975 1976 1977 1978 1979 1980

64-m ANTENNATELEMETRY BITRATES, bits/s

1. DOWNLINK SIGNAL LEVELS ASSUME ELA = 0 deg.2. BIT RATE THRESHOLDS ASSUME 0.001 DELETION RATE.

AU

GEOCENTRIC RANGE, AU

RECEIVED CARRIER POWER AT 26-m ANTENNA DSS, dBmW
to 18.5 kelvin and extend the potential range even further to 26.8 AU, which Pione

10 would reach at the end of 1981.

Although the last two items would have extended the maximum range to 31.3 AU 

early 1983, coincident with the projected life of the spacecraft, it was not thought 

the time that they could benefit Pioneer 10, not planned for Network implementatio

until after 1983. 

Over the course of time, these estimates turned out to be grossly pessimistic and, 

subsequent chapters will show, Pioneer 10 continued to maintain its downlink with th

DSN until it finally vanished on 31 March 1997. Pioneer 11 obtained some bene

from the low-noise feed-cone but not enough to enable it to achieve its desired dow

link telemetry rate of 1,024 bits per second.

Following their successful Jupiter encounters in 1973 and 1974, the Pioneer 10 and 1

spacecraft moved through the Viking Era, with two essentially trouble-free spacecraft o

solar system escape trajectories. Along the way, Pioneer 11 would return imaging da

from an encounter with Saturn in September 1979.

The Pioneer 10 and 11 missions would utilize every available enhancement to the DS

downlink capabilities to extend the life of the missions and to enhance their interpla

etary science return. The longevity of the spacecraft and this approach to mission desig

and planning would yield far-reaching results into the future, much further than cou

have possibly been foreseen in that era.

Pioneer Venus

Investigation of the planet Venus continued in 1978 with the launch of two spacecra

one of them a Venus Orbiter, the other a Venus Multiprobe. Managed by Ames Resear

Center as part of the very successful ongoing Pioneer program, the Venus Orbiter w

launched by Atlas-Centaur in May 1978, and the Venus Multiprobe in August 197

These two launches would also be noteworthy because they were last expendable laun

vehicles to be used for planetary launches before the newly developed Space Shuttle too

over all deep space launches in the 1980s. 

The Orbiter reached Venus on 4 December, followed five days later by the Multipro

on 9 December. After insertion into Venus orbit, the Orbiter mapped the Venus surfa

by radar, imaged its cloud systems, explored its magnetic environment, and observ

interactions of the solar wind. Advantage was taken of its many occultations to condu

116

Uplink-Downlink: A History of the Deep Space Networ
Earth-based radio science experiments to determine the refractivity, turbulence, and iono

pheric structure of the atmosphere.

On arrival at the planet, the Multiprobe spacecraft (bus) released four heat-resistant prob

to penetrate the Venus atmosphere at widely separated locations. Each probe contain

an S-band radio transmitter that continued to return telemetry measurements of atmo

pheric temperature, pressure, and density until it impacted the planet surface.

Both Pioneer Venus 1978 missions presented significant challenges to DSN engineerin

because they required a substantial amount of the new equipment and new technolo

then being installed as part of the MDS implementation program. In addition, th

Multiprobe mission presented unique operational problems because of the need to ra

idly acquire and simultaneously track all four probes as they were released into the Ven

atmosphere from the bus.

Shortly after arrival and insertion into Venus orbit, the Orbiter began a long series 

Venus occultations, during which the DSN conducted ninety S- and X-band radio sc

ence observations as the spacecraft alternately entered and exited obscuration by th

planet. Open-loop and closed-loop receivers together with wide- and narrow-band di

ital recorders were used to capture the S- and X-band radio science data on each occasio

Between occultations, normal telemetry data capture continued.

The initial occultations occurred only over DSS 14. The spacecraft periapsis passage w

allowed to move later each day until it reached the DSS 14/DSS 43 mutual view pe

od in January 1979. Thereafter radio science was conducted at both stations until passin

completely to DSS 43 later in 1979.9

Occultation radio science observations on the Orbiter were suspended for two da

on 8 and 9 December to allow the stations to give their full attention to the pro

entry event.

DSS 14 and DSS 43 had prime responsibility for the supporting probe entry events 

real time. They were to provide telemetry and Doppler data, and analog recordings 

the open-loop receiver outputs, and to establish and maintain an uplink to the lar

probe during the entry and descent period. After the probes had impacted the surfac

they were to support the bus until it, too, entered the atmosphere and was destroye

In conjunction with the stations of the STDN at Santiago, Chile, and Guam, th

would also provide recording for the Differential Long Baseline Interferometry (DLB

experiment.10

11

The Viking Era: 1974–1978
A special configuration had been implemented as part of the MDS at DSS 14 and DS

43 for the Pioneer Multiprobe mission to allow simultaneous reception of five carrie

and for the processing of four carriers in real time. For backup purposes, four ope

loop receivers with bandpass filters and analog recorders allowed for recording a wideban

spectrum around the anticipated carrier frequencies of the four entry probes. These da

could be played back in non-real time at CTA 21, and converted back up to S-ban

for reception and processing the Mark III-75 telemetry equipment.

DSS 11 and DSS 44 would support the bus during the entry period with comman

telemetry, and Doppler data while the 64-meter stations were tracking the four probe

DSS 42 would provide equipment for generating Doppler data from the third sm

probe. At DSS 14 and DSS 43, the operational complexity of dealing with ten sign

flow paths for the four probes and the bus gave cause for concern. Recalling that the

paths were all active simultaneously and that the time available for activating them on

the probes were released was about five minutes, it is not surprising that the operat

crews at the stations approached the Multiprobe entry event with some trepidation.

The fact that the entire event was supported perfectly, and resulted in the capture of 9

percent of the possible data from all four probes during the brief period (50–60 mi

utes) of their descent to the surface of Venus, attests to the care in planning, thoroughne

of the training, and the skill and dedication of all the DSN people involved.

118

Uplink-Downlink: A History of the Deep Space Networ
NETWORK ENGINEERING AND IMPLEMENTATION

The DSN Mark III System Design

The enduring design of the DSN Mark III Data System originated with a presentatio

by Walter K. Victor, N. A. Renzetti, J. R. Hall, and Douglas J. Mudgway to the Trackin

and Data Acquisition Organization and the Technical Divisions in October 1969. A

that presentation, Victor first proposed a radical new approach to the DSN archite

tural structure.11 It would be called the DSN Mark III-73 and would include the DSN

NOCC, GCF, and the MCCC. Due to institutional restructuring, the MCCC wou

be separated from the DSN in 1972, and thereafter was excluded from the scope of th

Mark III Data System.

Walter K. Victor deserved to be numbered among the founders of the DSN. Bringin

with him an engineering degree from the University of Texas (1942) and a brillia

mind, Victor came to JPL in 1953 to work on radio guidance systems for the Corpor

and Sergeant missiles then being developed for the Army. He was soon collaboratin

with a colleague, Eberhardt Rechtin, in developing more efficient receivers for trackin

very weak radio signals from distant missiles or space probes. Based on “phase-loc

tracking principles developed earlier by Rechtin and R. Jaffe of JPL, the “phase-lo

receiver” eventually became a key element of all deep space tracking stations. Walt Victo

association with the “phase-lock receiver” became legendary throughout the DSN.

When JPL made the transition to NASA in 1958, Victor became Manager 

Communications Systems Research in Rechtin’s Telecommunications Division. In th

years that followed, he moved to successively higher positions of authority within th

tracking and data acquisition organization. During that time, he directed many of th

major technical advancements that led to improvements in the performance, reliabili

and productivity of the Network. He left the Tracking and Data Acquisition Office 

1973 for higher responsibility elsewhere at JPL.

Tall, autocratic, and conservative in approach, Victor would not “suffer fools gladly.” A

one of his engineers described his meetings with Victor, “With Walt Victor, there w

no middle ground, no gray area. You were either right or wrong; you either knew, 

you did not know, the answers to his always detailed questions.” His penetrating min

breadth of experience, piercing gaze, and abrupt manner brought terror to many a

inadequately prepared engineer in the course of a technical presentation.

11

The Viking Era: 1974–1978
A very private man, not much given to socializing, Victor elicited great respect from h

coworkers, at both JPL and NASA Headquarters, by virtue of his unequivocal com

mitment to excellence in every problem, task, or project he addressed. He retired fro

JPL in 1987. 

As visualized by Victor, the DSN Mark III-73 Data System would comprise one su

net of 64-meter diameter antennas and one subnet of 26-meter diameter antenn

supplemented by an additional 26-meter subnet shared with the Manned Spaceflig

Network. Two launch support stations, one at Cape Canaveral (MIL 71) and one 

Johannesburg, South Africa (DSS 51), would provide near-Earth tracking coverage f

planetary missions, and a spacecraft-to-DSN compatibility test facility at JPL (CTA 2

would be used to verify the integrity of uplinks and downlinks before a spacecraft mov

to the prelaunch phase of activity. The station in South Africa was eventually dropp

from the plan for political reasons. Network control was to be exercised from a centr

facility at JPL (NOCC), which would have the necessary capability for the processin

display, and storage of network control data. (In its original form, the plan also inclu

ed a data processing facility for mission control, but this became irrelevant when th

MCCC was separated from the DSN.) The addition of a “simulation center” to th

DSN would provide simulated spacecraft data streams for use in end-to-end testing 

new installations at the tracking stations over real communications circuits, and trai

ing station personnel in new operational procedures.

Two important, new, and lasting basic concepts were introduced to form the basis f

future design of the Mark III data system: closed-loop control of major data systems 

minimize loss of data, and specific validation by the DSN of all spacecraft data deli

ered to the flight projects.

The first of these, “closed-loop control”, implied the development of a new capabili

that would continuously monitor the status of the Network and the real-time data stream

compare these to preestablished standards, and generate alarms when these values excee

ed specified limits. Immediate corrective action would follow. The new capability wou

become the DSN Monitor and Control System.

The “data validation” concept implied no alteration of, or delay to, the incoming spac

craft data by the validation technique. The validation process also included the abili

to determine the status of the DSN in real time, and to make these data available 

the flight projects.

120

Uplink-Downlink: A History of the Deep Space Networ
Finally, as a basic framework on which to design and manage the future Mark III Da

System, Victor identified a hierarchy of “systems and subsystems” for the Network an

its (then) three facilities: the SFOF, GCF, and DSIF. (As mentioned previously, the SFO

was later deleted from the plan and the DSIF became known as the DSS.)

The definition of the DSN Systems was logically based on the functions to be pe

formed, and became formalized as listed below:

DSN Tracking System

DSN Telemetry System

DSN Command System

DSN Monitor System

DSN Simulation System

DSN Operations Control System

A similar hierarchy was identified for each of the facilities based on its specific fun

tions as an element of the Network.

Because of its intuitive simplicity and inherent ability to create clear manageable inte

faces between them, the system hierarchy for the DSN, GCF, and DSS continues 

use today throughout the Network.

In a form substantially the same as originally proposed, the Mark III-73 Data Syste

was implemented in time to support missions in the closing years of the Mariner Er

and was soon followed by an upgrade to a Mark-III-74 model to support the maj

new missions of Pioneer and Helios. Then came the Viking mission to Mars.

Implementation for Viking

The process of DSN implementation to support missions in the Viking Era was esse

tially one of addition and modification. Except for the 64-meter stations in Austra

and Spain, which had come into service in 1973 and 1974, respectively, and the NOCC

all the facilities had been in existence and had supported many previous flight projec

in more or less the same form for several years.7 Further, the network configuratio

required for Viking launch and early cruise (up to February 1976) was substantially th

which already existed. The major increase in capability was not required for full plan

tary testing with the project until February 1976, well before the planetary encount

in June 1976. Therefore, the actual implementation was carried out in phases corr

sponding to the phase of the mission activity for which it was required.

12

The Viking Era: 1974–1978
Prior to March 1972, Network implementation plans had included the SFOF, since 

was at that time a part of the DSN. Following reorganization of the Offices of Trackin

and Data Acquisition and Computing and Information Systems in March 1972, th

SFOF was separated from the DSN, and the plans for a Network upgrade were rearrang

to encompass only the deep space tracking stations, compatibility test stations, groun

communications, and the NOCC. The former SFOF then became known as the Missio

Control and Computing Center (MCCC) to distinguish it from the NOCC, whi

resided in the same building (230) at JPL. The DSN and SFOF functions had orig

nally been conducted as a single entity under the control of the DSN. They were separat

in 1961 only to be recombined in 1963 and separated again in 1972.7

During 1972 and 1973, implementation activity related to Viking was relatively sma

partly because the Viking mission was being replanned from the cancelled launch 

1973 to a 1975 launch, and also because DSN attention was focused principally on th

Mariner Venus-Mercury mission.

By September 1973, however, implementation for the new CTA 21 had begun to mo

forward, and the longer range Viking implementation was finally planned. CTA 21 w

urgently needed to allow the all-important Viking multiple spacecraft testing to g

underway.

The implementation of CTA 21 made such good progress that a year later (Augu

1974) the Viking radio frequency and data system compatibility tests had been com

pleted using two Orbiter streams and one Lander stream simultaneously between CT

21 and the Mission Control Center. In the course of these tests, up to six data stream

had been passed across the interface and processed correctly, simultaneously with th

generation of two command links. This completed the implementation of CTA 2

Implementation at the STDN-MIL 71 site at Cape Kennedy and DSS 14 at Goldston

for support later in the year was in progress.

The end of 1974 saw the Block IV receiver installed at MIL 71 and the new statio

integrated with the NOCC. Block IV receivers for DSS 43 and DSS 63 were in pr

duction and expected to be installed before Viking launch, then projected for July 197

Construction of facilities for the overseas high-power transmitter installations were abo

complete at the Madrid site while an Australian contractor was about to begin work 

Canberra.

Despite the interruption for most of July to reconfigure for the Helios launch, and 

further diversion to cover the Pioneer 11 Jupiter Encounter in November 1974, th

122

Uplink-Downlink: A History of the Deep Space Networ
installation of the Viking planetary configuration was complete at Goldstone statio

DSS 14 and DSS 11 by January 1975. Testing of the new capabilities began immed

ately and soon indicated areas in which improvements were needed, particularly wi

regard to the analog and digital recording of original data records. Implementation 

the Viking planetary configuration at overseas stations in Madrid and Canberra we

slowed somewhat by the restrictions on configuration changes imposed during the Vikin

prelaunch test period.

Nevertheless, all implementation required for launch was completed by the time of th

first DSN-Viking Launch Readiness Review on 9 July 1975, and the DSN was declar

fully prepared to support both Viking launch and cruise operations.

DSN Mark III-75 Model

With the advent of full planetary operations on 20 July 1976, following the successf

landing of Viking Lander 1, the entire resources of the DSN were required to provi

simultaneous support for the two Orbiters and the Viking Lander.

In addition to Viking, the DSN was also being called upon to provide support f

Pioneers 6–11 and the Helios 1 and 2 solar missions. The extent of the coverage involv

can be adjudged from Figure 3-1, which shows all the missions in flight at the time

The support required by all of these users of the Network encompassed telemetry, com

mand and tracking support, error-free data transmission services from Madrid, Spai

Canberra, Australia; and Goldstone, California; as well as Network control and mon

toring and production of complete data records.

The resources included three 64-meter stations, six 26-meter stations, DSN an

NASCOM ground communications facilities, and the NOCC. The configuration of th

Network was then called the DSN Mark III-75.

The DSN Mark III-75 was, at this time, the latest in a progressive succession of co

figurations or models based on the original DSN Mark III Data System design beginnin

with the Mark III-73. Each Model represented a new increment of DSN capabilit

driven by the tracking and data acquisition requirements of the future missions (s

Figure 3-1). The key telemetry characteristics of each of the models through the per

od 1973–76 reflect the steady development of DSN capability in this period. As ca

be seen in the following table, additional telemetry characteristics were added to th

12

The Viking Era: 1974–1978
Mark III-73 Model and the result was the Mark III-74 Model, to which other cha

acteristics were added to create the Mark III-75 Model.13

Key Telemetry Characteristics for Mark III System Models 73 Through 75

Deep Space Network Mark III-73

• Multimission capability at each station for receiving and formatting

uncoded and block-coded telemetry.

• Special software for Pioneer convolutional coded telemetry.

• Centralized monitoring of Telemetry System performance by observation of project displays in the MCCC.

• Capability at each station for a single carrier, dual subcarrier, and formatting for high-speed and wideband communications.

• Recording of pre- and post-detection analog records with nonreal-time

playback.

• Production of digital Original Data Record (ODR) at each DSS and

playback via manual control or automatic response to project inputs.

• Real-time reporting of telemetry status at the station to the Monitor

and Control Subsystem.

Deep Space Network Mark III-74

• Multimission capability for sequential decoding of long constraint convolutionally coded telemetry data up to 4,000 bits per second using

the Fano algorithm, for both Pioneer and Helios.

• Real-time monitoring of Telemetry System performance at the NOCC.

Deep Space Network Mark III-75

• Capability at the 64-meter DSS to handle multiple carriers (up to

four) and multiple subcarriers (up to six) with decoding, ODR, and

formatting for communications circuits.

124

Uplink-Downlink: A History of the Deep Space Networ
• Centralized monitoring of Telemetry System performance at the

NOCC, and reporting via the DSN Monitor and Control System.

• Central logging (on a Network Data Log) of all data received at the

DSS, with gap accounting, and automated recall of missing data from

the DSS ODRs.

• Generation of a time-ordered, gap-free record of all received data

called an Intermediate Data Record (IDR) for delivery to the flight

project.

• Generation of Telemetry System predicts and configurations for transmission to each DSS for use in the manual control of system

elements.

The ground communications capability associated with the Mark III-75 model provi

ed for transmission of formatted telemetry data from each DSS to the NOCC an

MCCC. The communication circuits were furnished by NASCOM, and consisted 

one 4,800-bit-per-second high-speed line from each DSS, and one additional 28.

kilobit-per-second wideband line from each 64-meter DSS in Spain and Australia, wi

50 kilobits per second from Goldstone.

The 64-meter Stations

A functional block diagram of the DSN Mark III-75 configuration for the 64-met

stations (DSS 14 at Goldstone, DSS 43 at Canberra, and DSS 63 at Madrid) is show

in Figure 3-10.

Two Block III receivers and two Block IV receivers provided a redundant capability f

up to three radio frequency carriers simultaneously; e.g., two Viking Orbiters and on

Viking Lander. Block III receivers were capable of only S-band reception, while Blo

IV receivers could receive at either S-band or X-band. Two open-loop receivers provi

ed for radio science occultation and solar corona experiments.

Six subcarrier demodulators were connected by an extremely flexible switching matr

to associated block decoders symbol synchronizers, and data decoders which, togeth

with the telemetry and command processor, provided the capability to handle six simu

taneous data streams, or two subcarrier data streams per spacecraft.

12

The Viking Era: 1974–1978
The block decoders were used to decode the block-coded data streams from the Vikin

Orbiters at 16,000 bits per second and 1,000 bits per second from the Lande

Convolutionally coded data from Pioneer or Helios were handled by the data decode

at 512 bits per second and 4,096 bits per second, respectively. Uncoded data, up 

about 33 bits per second, could be handled directly by the telemetry and comman

processor in addition to its other command and telemetry data handling tasks.

The Data Decoder Assembly (DDA) and the Telemetry and Command Processor (TC

delivered the processed telemetry streams to the ground communications subsystems f

transmission via global NASCOM high-speed and wideband communication circuits 

the GCF terminal at JPL. From that point the data could be directed to the approp

ate Mission Control Center for flight project use and to the NOCC for monitoring an

validation and recording purposes. 

Under TCP control, two Command Modulation Assemblies and dual transmitter excite

afforded redundant paths to either a 20-kilowatt or 100-kilowatt transmitter for uplin

command purposes, one uplink at a time. At Goldstone only, a 400-kilowatt transm

ter could be used in place of the 100-kilowatt transmitter, if necessary.

Radiometric (Doppler and ranging) data were generated by the station tracking subsy

tem, which consisted of two Doppler counters and two Range Demodulation Assemblie

This arrangement, together with a Planetary Ranging Assembly, provided S- or X-ban

ranging simultaneously with S- or X-band Doppler. When tracking a spacecraft close 

the Sun, the Planetary Ranging Assembly could be replaced by the Mu-II Rangin

Machine, which embodied a different technology to give better ranging performance 

the presence of solar noise.

Digital data records were made by pairs of 9-track high-density tape recorders attach

to the DDA and analog records of baseband, and detected data were made by Amp

FR1400 analog tape recorders. Two high-performance Honeywell machines were ava

able for baseband playback at the stations when necessary.

Rubidium frequency standards were the basis for all station tracking and frequency re

erences. Interstation time synchronization to 20 microseconds was accomplished by mea

of an X-band Moon bounce link from the Madrid and Canberra stations to the Netwo

master clock at Goldstone.

The Mark III-75 Data System was designed to permit the maximum flexibility in switc

ing and interchange of assemblies in the telemetry, command, and tracking subsystem

126

Uplink-Downlink: A History of the Deep Space Networ
Figure 3-10. Functional block diagram of the DSN Mark III-75 configuration for 64-meter station

12

The Viking Era: 1974–1978

FPO

3 pg fold out of chart
128

Uplink-Downlink: A History of the Deep Space Networ

Figure 3-11. Functional block diagram of the DSN Mark III-75 configuration for 26-meter station

FPO

3 pg fold out of chart
This system also provided some degree of redundancy when stations were called upo

to support planetary operations for three spacecraft simultaneously. This approach enabl

the stations to be rapidly reconfigured to support the different needs of the Vikin

Pioneer, and Helios inflight missions.

The specific configurations needed for each mission were separately defined and cod

into a Network Operations Plan for use by the station operators in manually setting u

the station equipment.

The 26-meter Stations

A functional block diagram of the DSN Mark III-75 configuration for the six 26-met

stations (DSS 11 and 12 at Goldstone, DSS 42 and 44 at Canberra, and DSS 61 an

62 at Madrid) is shown in Figure 3-11.

Because DSS 42 and 61 shared the same control room and some of the same equi

ment as the 64-meter stations (DSS 43 and DSS 63), they were known as “conjoin

stations in the Viking Era.

Two Block III receivers provided a capability for receiving two S-band downlink car

ers if necessary. Generally, they were used for only one carrier with a backup receiv

since the two subcarrier demodulators that followed could accommodate only one low

rate (33 bits per second) and one medium-rate (2,000 bits per second) data chann

Block coding at 2,000 bits per second or less was accomplished in the data decode

feeding the symbol synchronizers.

Two XDS 920 computers, known as TCPs, performed the data processing functions f

two telemetry channels and two command channels. Each TCP could format and ou

put telemetry data to a single GCF high-speed communications line for transmission 

JPL. Each TCP could also deliver command data to a command modulation assemb

for modulating a single S-band exciter and 20-kilowatt transmitter for transmission 

commands to the spacecraft.

S-band ranging and differenced range versus integrated Doppler (DRVID), data ge

erated by the planetary ranging assembly was available only at DSSs 12, 42, and 6

At the conjoint stations, the ranging capability was shared with the 64-meter st

tions, so that either, but not both stations, could provide ranging support at an

time. Using their Block III Doppler extractors, all 26 stations could also generate 

band Doppler. The Tracking Data Handling (TDH) assembly was used to samp

12

The Viking Era: 1974–1978
and condition the radiometric data for transmission to JPL via the GCF high-spee

communication circuits.

Digital data were recorded at the output of the TCP. Baseband and detected analo

records were made at the input and output of the Subcarrier Demodulator Assembly

At the conjoint stations, a single crew was used to operate both stations from the on

control room. To reduce the demands upon these crews during operations, the statio

monitor and control functions were exercised from a newly developed Station Monit

and Control Assembly known as the SMC IIB. The SMC provided remote control 

some functions, such as receiver tuning, and, by bringing other monitoring functio

to a single console, permitted the station to be operated during periods of high activ

ty with fewer operators than would otherwise have been required.

High-Power Transmitter

To meet an early Viking requirement for simultaneous commanding to two spacecra

(Orbiter/Orbiter or Orbiter/Lander) from a single antenna, the DSN planned to provi

dual 10-kilowatt uplinks from a single 100-kilowatt transmitter.14, 15 In early 1973, th

dual carrier single transmitter scheme presented technical difficulties that were not resol

able at the time and a recommendation was made that separate antennas with comman

capability at the same longitude be used to meet the Viking requirements. However, fu

ther evaluation of the uplink performance of the Viking Lander under worst-case conditio

revealed that, irrespective of the dual-carrier requirement, there remained a need for 

100-kilowatt transmit capability at the two 64-meter stations (DSS 43 and DSS 63), an

in addition, a 400-kilowatt transmit capability at DSS 14 at Goldstone. These latt

enhancements would “avoid unacceptable risks and/or constraints to the Viking Land

operations, particularly Mission B.” Accordingly, these big new transmitters now becam

part of the Viking planetary configuration required at all the 64-meter stations.

Originally, the DSN stations included 10-kilowatt to 20-kilowatt S-band transmitters 

provide the command and tracking data uplink to the spacecraft. However, in 1970, a 10

kilowatt high-power S-band transmitter had been installed at the new 64-meter antenna 

Goldstone, and planning was initiated to provide similar transmitters at the other 64-met

antennas in Spain and Australia. Driven by the Viking requirement however, the plans we

accelerated to have the DSS 63 subsystem installed and transferred to operations for Vikin

support by July 1975, followed by the DSS 43 subsystem in mid-October 1975.16

130

Uplink-Downlink: A History of the Deep Space Networ
To save time, vendors shipped many of the components directly to the overseas site

Other components were sent to the high-power transmitter test facility at (DSS 1

Goldstone for testing before overseas shipment.

By June 1974, elements of the DSS 63 transmitter had been assembled into a test fi

ture to simulate other parts of the transmitter; they were run up to full power (1 megawat

for 24 hours. These tests assured sufficient wattage from the power supply group f

either a 100-kilowatt klystron (Varian X-3060) or a 400-kilowatt klystron, which w

being developed for the DSN at Varian but was not available at that time. In July, fo

technical personnel from Spain arrived at Goldstone for a short period of training pri

to dismantling and shipping the subsystem to Spain for installation on the 64-met

antenna. After following a similar procedure, technicians shipped the DSS 43 transm

ter to Goldstone in December 1974.

The construction of facilities for the new transmitter subsystem began in August 1974 

DSS 63. The facilities consisted of a building to contain the transformer/rectifier, a filt

choke and control junction box, and a set of concrete pads for mounting the 1,750-hors

power (1,300-kilovoltampere), 400-cycle-per-second motor generator set. Housing was al

required for the motor control center, auxiliary heat exchanger, the distilled water reple

ishing unit, and underground water tanks. The high-power klystron would be mount

in the tri-cone on the antenna itself and connected via waveguide couplings to the ante

na microwave system. High-voltage power supplies and control equipment were to 

mounted in the antenna pedestal, and a heat exchanger mounted in the alidade (no

tipping part of the antenna structure) would supply the klystron with distilled water coolan

As the facilities became available, equipment was assembled and installed, and chec

outs proceeded rapidly. Final overall and load testing was completed without incide

and the 100-kilowatt high-power transmitter at DSS 63 became operational and ava

able to support Viking in July 1975. Events at DSS 43 followed a similar pattern an

the 100-kilowatt transmitter became operational at DSS 43 in October 1975.

In April 1974, the high-power transmitter at DSS 14 was shut down for approximat

ly four weeks to install an experimental 500-kilowatt klystron that would raise the maximu

transmit power to 400 kilowatts as required for Viking.

Early in 1976, the klystron tube developed a short circuit in its filament assembly and h

to be returned to the manufacturer, Varian Associates, for repair. By that time, however, 

had been determined that the real advantages of the 400-kilowatt capability as compar

to the 100-kilowatt capability were slight, and the 500-kilowatt klystron was held as bac

13

The Viking Era: 1974–1978
up in the event of some unforeseen emergency.17 Fortunately, neither of the Viking Lande

for whose emergency support the backup was intended, ever had need to use it. Even 

the last Viking Lander fell silent in February 1983, an analysis of the telecommunicatio

link showed that at a transmitter power of 100 kilowatts nominal (actual power of 80 kil

watts), there was a 10- to 14-decibel margin for command with the Earth antenn

pointing-angle passing through the side lobes of the lander spacecraft antenna.18

Mars Radar

In contrast to the 1971 and 1973 Mars radar opportunities, which were conducted 

S-band frequencies, the 1975 Mars observations of the Viking landing sites were co

ducted at X-band. This was due in part to the availability of an experimental high-pow

(400-kilowatt) X-band transmitter at DSS 14, and in part to the increased emphasis o

an evaluation of the Mars landing site characteristics, particularly surface roughness.

The observations were due to commence in December 1975, while the Viking spac

craft were in the cruise phase of their missions.19, 20

At that time,21, 22 the experimental X-band transmitters included two, 250-kilowatt, Varia

VA949J klystrons in a four-port hybrid arrangement, which would combine the tw

individual outputs into a single waveguide to deliver a nominal output power of 40

kilowatts. Klystron failures and other hardware problems plagued the early attempts 

make successful radar observations, but in the last days of December 1975, two goo

observations were made at a power level of 165 kilowatts.

As the Earth-Mars range increased in the first months of 1976, intense efforts were ma

to increase the Mars radar transmitter power to its full 400-kilowatt rating. Varian Associat

contributed significantly to this effort by responding rapidly to DSN engineers’ calls f

modification or refabrication of klystron components. While this work was in progre

Mars radar data gathering continued as opportunity allowed. By the end of Februa

1976, problems in the crow-bar protective circuits, high-voltage power supply, and kl

stron body current had been identified and corrected, and the radar was delivering 

full rated output of 400 kilowatts at X-band. From that point on, all Mars radar trac

were conducted at full-power output.

By the end of April 1976, the strength of the radar signal returns from the planet h

fallen to about one-eightieth of their strength in December 1975, when Mars was clo

est to Earth. As a consequence, the data became too noisy for practical use, and th

data processing technique was changed from the range-gated technique to a continuo

132

Uplink-Downlink: A History of the Deep Space Networ
spectrum technique. This change resulted in less noise, but there was some loss in re

olution compared to the former technique.

During May and June 1976, the Mars radar facility at Goldstone continued to suppo

an intensified program of Mars observations. Also during this time, additional observ

tions of overlapping areas of coverage were provided by the Cornell Radio Astronom

Observatory at Arecibo, Puerto Rico.

By mid-June, the data had become too noisy for analysis and the X-band radar suppo

for Viking was concluded.

The planetary radar work continued to expand and improve in the years ahead to becom

a unique part of the DSN Science program. Eventually it became known as the Goldston

Solar System Radar (GSSR) and is discussed in more detail in later chapters. 

The Introduction of X-band

The improvement in uplink and downlink performance that could result from oper

tion at frequencies higher than S-band (approximately 2,000 to 3,000 MHz) had lon

been recognized in DSN engineering and planning. However, such improvements cou

not be realized without corresponding improvements in the microwave componen

which together comprise the antenna/microwave/receiver subsystem. Simply changin

the operating frequency alone would not be effective.

A considerable effort in research and development had been in progress during the ear

1970s to develop feed-cones,23, 24, 25 antenna surfaces, masers, and waveguide comp

nents that would operate effectively at X-band frequencies (approximately 8,000 to 9,00

MHz) in the operational Network environment.

By 1973, this work progressed to the point where the first inflight demonstration of a

X-band deep space telecommunications link could be carried out using the Mariner 1

(Mariner Venus-Mercury [MVM]) spacecraft to carry an S/X-band transponder.26 In add

tion to the standard S-band uplink and downlink, the spacecraft transponder wou

transmit an X-band downlink carrier signal that would be coherent with the normal 

band carrier. The X-band carrier would not carry telemetry but could be switched 

carry a range modulated signal. The demonstration was officially called an S/X-ban

experiment to distinguish it from the prime MVM mission objectives, and because th

outcome of the effort was far from certain.

13

The Viking Era: 1974–1978
There remained the problem of how to adapt the DSN 64-meter antennas to recei

X-band signals in addition to their existing transmit-and-receive capability on S-ban

The DSN’s Advanced Technology program provided the answer. Known as the “Dichro

Feed,” this complex microwave device is discussed in more detail in chapter 6 In co

cept, this would be accomplished by adding an ellipsoid reflector over the S-band fe

and a dichroic mirror over the X-band feed, with each feed-horn mounted in a sep

rate cone structure. The dichroic mirror would pass an X-band signal directly into th

X-band feed, but would direct an S-band signal on to the ellipsoid reflector. The elli

soid reflector would then refocus the S-band signal to enter the S-band feedhorn. 

The tri-cone on the 64-meter antenna at DSS 14 would be the first to be modifie

When this very complex installation was completed in early 1973, performance mea

urements attested to the excellence of the design. No signal degradation was observ

at S-band, and measured loss at X-band was less than 0.2 decibels. There was no war

ing or distortion of the structures, sometimes caused by thermal effects, when the S-ban

uplink was transmitting at full power.

The other components required for the S/X-band experiment, the new Block IV recei

er, the Block IV exciter, and a new S/X-band ranging system, were available by th

middle of 1973, and verified for compatibility with the onboard flight radio system.

During the early portion of the MVM mission, the S/X-band equipment experience

many problems with noise, instability, and Doppler cycle slips. Gradually, the pro

lems were identified and corrected, and by the Mariner 10 superior conjunctio

during May and June 1974, the DSN was able to provide dual frequency S/X-ban

Doppler, range, and open-loop receiver data for radio science support. This suppo

provided the first opportunity for spacecraft dual frequency analysis of solar coron

and gravity effects, and marked the first demonstration of X-band downlink cap

bility in the Network.

The MVM S/X experiment had demonstrated the viability of an X-band downlink an

the considerable advantages of an S/X-band for radio science; this experience was to 

carried a step further in the Viking mission.

Like Mariner 10 (MVM), both Viking Orbiter spacecraft were fitted with S/X-ban

transponders; i.e., they would receive an S-band uplink and would transmit an S-ban

downlink together with a coherent X-band downlink.

134

Uplink-Downlink: A History of the Deep Space Networ
For Viking support, both DSS 43 and DSS 63 were fitted with the dichroic plates an

the Block IV receivers and exciters necessary for S- and X-band receiving capability, 

had been done at DSS 14. Based on the results from the MVM mission, the Vikin

radio science and ranging requirements were much more stringent in terms of nois

stability, and cycle slips, than had been the case for Mariner 10.

Because of this new capability, the Radio Science experiments became an important pa

of the DSN support for Viking. Earth occultation, solar corona, and general relativi

experiments were carried out successfully using the DSN S/X facilities.

In late 1975, at the end of the Viking Prime Mission, the Viking Radio Science Tea

reported the following:

Since November 1975 when the X-band transponders on both Orbiters

were turned on, several hundred S- and X-band Doppler and ranging passes

of excellent data quality have been acquired during Mars planetary operations. These data were extremely useful in evaluating the new X-band system

performance, monitoring solar flares and solar corona noise, and for the

charged particle calibration of Doppler and ranging data. The data afforded

the first practical demonstration of the validity of the dual frequency calibration of charged particle effects in the interplanetary medium. Also, the

achievement of a 0.1 percent accuracy in the Viking general relativity experiment depended entirely upon the near simultaneity of the S-band and

X-band tracking of an Orbiter and the S-band tracking of a Lander.27

The DSN S/X-band capability had arrived and would form the basis for all radio sc

ence observations for all flight missions from this time forward. 

The 64-meter Antenna Problems

In mid-August 1976, the 64-meter antenna at DSS 14 (Goldstone) developed a pote

tially serious problem when it became difficult to maintain a satisfactory oil film heig

between the hydrostatic bearing and the azimuth bearing pads. The area of conce

lay between the 128- and 140-degree azimuth positions of the antenna. This parti

ular area of the hydrostatic bearing had been a problem since the antenna first cam

into service in 1966. The previous history predicted a failure condition arising abo

every three months, although the film height had been stable for several months 

that time. The last maintenance that had been carried out about three months ear

er (in June) used a shimming technique that had reached its limits and could n

13

The Viking Era: 1974–1978
longer be used for further maintenance. Further delay in correcting the problem wou

only increase the chance of a catastrophic failure of the antenna’s azimuth rotatio

bearing.

A new technique, which required an 18-hour downtime on seven successive days, h

been proposed but never tried out, and therefore carried with it some question as 

how effective the proposed “fix” might be. Occurring as it did at such a critical time 

the Viking mission, just before the second Mars landing, the situation and issues involv

were cause for great concern to the DSN.

Rather than proceeding with the “fix,” a plan was put into effect which require

daily monitoring and reporting of the oil film height against an established set 

safety criteria. In this way some warning of a deteriorating condition would becom

visible, permitting a reevaluation of the risk involved in continuing operations. It w

also decided that a firm work plan for refurbishment would be scheduled for 1

November 1976, or sooner if the bearing showed any sign of deterioration prior 

that time. This plan worked very well. The oil film height remained stable throug

5 November, at which time the operational usage of DSS 14 was such that the wo

was carried out on alternate weekdays and brought to a successful conclusion on 1

November 1976.

A further incipient problem had been known for some considerable time in the ball an

socket joint on the antennas at DSS 43 and DSS 63. An inspection carried out in la

1975 revealed that the ball joint that permitted the pad to rotate as it followed the co

tours of the hydrostatic bearing runner was frozen because of improper lubrication. 

cross-sectional diagram of the hydrostatic bearing and the ball joint assembly is give

in Figure 3-12.

Prolonged attempts to force grease into the joint under high pressure were unsu

cessful, so a spare unit was shipped to Canberra in January 1976. However, prior 

installation on site at Canberra, this unit was found to be defective and was return

to the United States. New units were ordered for both DSS 43 and DSS 63 on

since the DSS 14 units were satisfactory. Installation was postponed to coincide wi

the Viking solar conjunction period in November and December, and the statio

downtime for the MDS work in Australia. The installation was successfully comple

ed during that time. 

136

Uplink-Downlink: A History of the Deep Space Networ
DSN Mark III Data System Project

The concepts of the DSN Mark III Data System established by Victor in 1969 we

updated, refined, and developed into a Mark III Project Plan by Easterling in 1974.

Easterling’s fundamental objective in planning the Mark III project was to provide su

port to flight projects in the 1973–1978 period and establish a standard, easily manag

interface with the MCCC at JPL and with other remote POCCs. A key factor in accom

plishing this objective was seen to be the development of a Network Control System th

would be entirely separate from and independent of the hardware and software used b

the flight projects. The upgraded Network would include new technology in radiometr

data generation using two station radio-interferometry techniques, increased use of autom

tion throughout the Network, and real-time transmission of spacecraft video data from t

DSSs to the MCCC using a global network of wideband communication circuits.

The plan advocated a phased design approach to hardware implementation with form

reviews at the completion of each phase, culminating in acceptance tests and a form

13

The Viking Era: 1974–1978

Figure 3-12. Hydrostatic bearing and ball joint assembly.

ALIDADE STRUCTURE

BOLTED

INTERFACE

FILM HEIGHT

LAMINATED SHIMS

GROUND SHIMS

SOLE PLATE PEDESTAL

GROUT

HYDROSTATIC BEARING RUNNER

HYDROSTATIC BEARING PAD

WT ≈ 5600 kg

LUBRICATED

SURFACE

BALL AND

SOCKET JOINT

WT ≈ 2700 kg

CORNER WELDMENT

WT ≈ 1088 Mg
transfer to operations status. An efficient, cost-effective software design philosophy deve

oped by a software technology group would employ structured, top-down programmin

techniques to provide for simple interfaces, well-controlled development, and easily mo

ified programs. A phased design approach culminating in acceptance tests and transf

to operational status would be used in producing all DSN software programs. Aft

transfer, DSN software would be subject to a rigorous program of configuration co

trol and management, maintained by a centralized DSN Software Library.

The Network was defined to include five Network systems: Tracking, Telemetry, Comman

Monitor and Control, and Test and Training. Lower tier subsystems were defined for ea

of the three elements of the Network: Deep Space Stations, Ground Communication

and Network Control. The Network systems and subsystems are shown in Figure 3-1

The upgraded Network, which no longer included the SFOF, would be identified 

DSN Mark III-77 and is shown in Figure 3-14.

Working within this hierarchical framework, engineers developed key characteristics f

all systems and subsystems which reflected the known and anticipated requirements 

the NASA Mission Set through 1981.

138

Uplink-Downlink: A History of the Deep Space Networ

Figure 3-13. Mark III-77 Network systems and subsystems.

DSN MARK III NETWORK

NETWORK SYSTEMS (5)

• DSN TRACKING

• DSN TELEMETRY

• DSN COMMAND

• DSN MONITOR & CONTROL

• DSN TEST & TRAINING

GROUND COMMUNICATIONS

SUBSYSTEMS (5)

• HIGH SPEED DATA

• WIDEBAND DATA

• VOICE

• TELETYPE

• MONITOR & CONTROL

NETWORK CONTROL

SUBSYSTEMS (7)

• TRACKERS

• TELEMETRY

• COMMAND

• MONITOR & CONTROL

• TEST & TRAINING

• SUPPORT

• DISPLAY

DSS SUBSYSTEMS (12)

• ANTENNA MECHANICAL

• MICROWAVE

• RECEIVER/EXCITER

• TRANSMITTER

• FREQUENCY & TIMING

• TECHNICAL FACILITIES

• PRE/POST DETECTION

 RECORDING

• TRACKING

• TELEMETRY

• COMMAND

• MONITOR & CONTROL

• TEST & TRAINING
The telemetry system would take advantage of improved telecommunications capab

ity to handle data rates up to 115 kilobits per second at Jupiter distance. It wou

accommodate multiple data streams and perform the block decoding, sequential deco

ing, and maximum-likelihood convolutional decoding functions, using standa

techniques. The command range and command data rate would be extended and a

improved “store and forward” command transmission process would be introduce

Radiometric data types would then include long baseline interferometer data, as w

as planetary ranging and Doppler observables. The introduction of Hydrogen Mas

frequency standards in place of the older Rubidium Standards would improve the acc

racy and stability of all radiometric data types to improve the uncertainties in spacecra

navigation targeting parameters.

13

The Viking Era: 1974–1978

Figure 3-14. General configuration of the DSN Mark III-77 Network.

GOLDSTONE

CANBERRA

MADRID

DSS 12

DSS 11

26M

DSS 14

64M

DSS 43

64M

DSS 62

DSS 44

DSS 42

DSS 63

64M

DSS 61

MIL 71*

LAUNCH SUPPORT/

COMPATIBILITY

TEST STATION

REMOTE***

INFORMATION CENTER

REMOTE***

OPERATIONS CENTER

REMOTE MISSION**

OPERATIONS CENTER

TO/FROM SPACECRAFT

ASSEMBLY AND TEST

FACILITY

SPACECRAFT/DSN

DEVELOPMENT/

COMPATIBILITY TEST

AREA CTA 21

MISSION SUPPORT

AREA

• MISSION A

• MISSION B

• MISSION C

MISSION COMPUTING

AND CONTROL CENTER

MISSION OPERATIONS

CENTER

NETWORK CONTROL

SYSTEM

CONVERTED TO 64-METER

ANTENNA POST-1977

* OPERATED BY STDN

** INTERFACES WITH DSS

*** INTERFACES WITH MCCC

OTHER RANGE AND

NETWORK SUPPORT

C

O

M

M

C

O

M

M

D

S

N

G

R

O

U

N

D

C

O

M

M

U

N

I

C

A

T

I

O

N

S

A

N

D

N

A

S

C

O

M

C

O

M

M
Network operations would be conducted from an NOCC using dedicated facilities 

serve multiple missions at several locations simultaneously. It would also include a fo

malized DSN scheduling procedure based on a 7-day, 8-week, 52-week, and 5-ye

Network allocation plan.

Improved management of the operational interfaces between the flight projects and th

DSN would result from the newly defined DSN Monitor and Control, and Test an

Training capabilities.

The GCF capability for duplex high-speed data transmission would be raised from 4,80

bits per second to 7,200 bits per second, while the wideband capability would increase fro

28.5 kilobits per second to 50 kilobits per second from all sites to JPL. Up to 230 kilob

per second would be available from Goldstone to JPL. The GCF would create a GCF l

of all flight project data generated by the DSN and deliver it on a negotiated schedule.

The DSSs would be upgraded with S- and X-band downlink capability for tracking an

telemetry and for acquiring up to five spacecraft in one antenna S-band beam width

Finally, the plan proposed a management approach to carry out the Mark III-77 pro

ect. It included an overall Project Manager, as well as an Implementation Manager f

each of the Network Data Systems, and for Quality Assurance and Reliability. The ma

agers were to be supported by cognizant system and subsystem engineers. Guidelin

were also given for scheduling, and progress and problem reporting. 

It was early 1974, and the window of opportunity for implementation of these maj

changes in the Network was approaching. The window would open at the end of th

Viking Prime Mission (last quarter of 1976) and close just before the Pioneer Ven

Prime Mission started (second quarter of 1978). There was no time to lose. Implementatio

Task Managers were appointed for the data systems, and began to develop technic

requirements derived from the key characteristics contained in the plan, and schedul

based on the rapidly approaching window.

The largest of the tasks included several of the Network systems, and for that reaso

was called the Mark III Data Systems Implementation Task; it was established in Februa

1975 with Paul T. Westmoreland as Task Manager.

Paul T. Westmoreland started at JPL in February 1960 as one of the original enginee

in Renzetti’s Communications Engineering and Operations Section. Except for a tw

year lateral transfer to the Mission Control and Computing department in 1977, h

140

Uplink-Downlink: A History of the Deep Space Networ
rose through the DSN to become the assistant laboratory director for tracking and da

acquisition in 1997. Born and educated in California, Westmoreland received a B.S

in electrical engineering from USC in 1960, just prior to joining JPL, and a maste

degree in the UCLA Engineering Executive Program in 1968.

Westmoreland’s early work led to the introduction of digital computing techniques f

operational control of the Network in the mid-1960s. Based initially on Scientific Da

Systems (SDS) 910- and 920-type computers, and subsequently on Modcomp machine

and later still, on distributed computing techniques, this approach provided the oper

tional flexibility that was the key to the future success of the Network control process. A

the applications for digital technology proliferated in the Network, so did the requiremen

for software to drive the digital processes. In collaboration with Walt Victor, Westmorelan

introduced new and innovative software standards that provided management with insig

and control of the cost and status of formerly runaway software development processes

Later in his career, he directed the DSN Systems Engineering Office, where he was ul

mately responsible for the overall architectural design and growth potential of the Networ

In 1997, he was appointed director of the Telecommunications and Mission Operatio

Directorate. 

Paul Westmoreland was a pleasant though serious man for whom pride in his appea

ance complemented obvious pride in his achievements. His well-cut suits with fashionab

ties were notable among his more casually dressed coworkers. He was an expert ba

room dancer, and he cast gold costume jewelry as a hobby. He was highly respected 

JPL and at NASA Headquarters for both his technical judgment and his fiscal astut

ness. His management style owed much to his early years at JPL when Rechtin an

Victor held the positions that he would later hold. In a real sense, the Network’s ab

ity to support many of the major spacecraft-related projects described in this histo

owes much to the technical foresight and budgetary awareness of Paul Westmoreland

He retired from JPL in 1998.

Mark III Data System (MDS) Implementation

A plan for implementing the portion of the Mark III project that involved the pr

cessing and transport of all data within the Network was issued by P. T. Westmorelan

in February 1975.29 The “Westmoreland plan” was intended to embody the princip

features of project management, system and hardware design, and software design ph

losophy enunciated by Easterling in the Project Plan.30

14

The Viking Era: 1974–1978
This major Network-wide reconfiguration was called the DSN Mark III Data Syste

(MDS) implementation task and involved all stations of the Network in sequence, throug

out 1977 until completion, on schedule and under budget, in mid-1978.

In carrying out this task, the DSN would replace all its obsolete SDS-920 compute

with new MODCOMP II-25 minicomputers. Each of the nine tracking stations in tu

would have its old telemetry and command processors replaced with new machines an

software, and then be requalified to resume inflight support. The implementation ta

schedule, which was carefully planned to avoid impact with the inflight mission su

port activity and the launch of the new Voyager mission to Jupiter and beyond, is show

in Figure 3-15. 

Because of the size of the effort involved in this task, the basic implementation w

accomplished by an integration contract with Univac Corporation to provide for th

fabrication, test, and integration of the Modcomp and other assemblies to form st

tion-level configurations for onsite installation and test by traveling teams of DS

engineering personnel. Three basic station-level configurations were designated, on

for the 26-meter stand-alone stations (DSS 11, 12, 44 and 62), one for the 26/6

meter conjoint stations (DSS 42/43 and DSS 61/63), and a 64-meter configuratio

142

Uplink-Downlink: A History of the Deep Space Networ

Figure 3-15. DSN Mark III Data System implementation schedule, 1977.

• VIKING

• HELIOS 2

• PIO VENUS

• MUS 77

• CTA 21

• MIL 71

• DSS 12

• DSS 62

• DSS 44

• DSS 14

• DSS 42/43

• DSS 61/63

• DSS 11

1976

1st PERIHELION 2nd PERIHELION 3rd PERIHELION

ORBITER 

LAUNCH

GDS MOS LAUNCH

TWO-MONTHS DOWNTIME FOLLOWED BY

TWO-MONTHS TEST AND TRAINING AND FLIGHT SUPPORT

S/W DEV

PIO,

SUP HEL VIK

START OF 5-MONTHS DOWNTIME DSS 12

FOR S-X CONVERSION JULY 1, 1978

PRIME MISSION REL EXP EXTENDED MISSION-EARTH OCC EOM

1977 1978

AM J J A S O N D J FM AM JJAS O N D J FM A M
for DSS 14 and DSS 63, as well as for CTA 21 at JPL and MIL 71 at Merr

Island, Florida. Each configuration contained up to three of each of the followin

major assemblies:

• Telemetry Processor Assembly (TPA)-Assumed the telemetry functions

of the existing DSS Telemetry and Command Processor (TCP) by

replacing the older XDS-920 computers with new Modcomp minicomputer to form a separate Telemetry Subsystem. The existing

Symbol Synchronizer remained in place.

• Command Processor Assembly (CPA)-Assumed the command functions of the existing DSS Telemetry and Command Processor (TCP)

by replacing the older XDS-920 computers with new Modcomp minicomputer to form a separate Command Subsystem. The existing

Command Modulation Assembly remained in place.

• Metric Data Assembly (MDA)-Replaced the existing DSS Tracking

Data Handling Subsystem (TDH) and functioned as part of the DSS

Tracking System.

• Communications Monitor and Formatter (CMF)-Functioned as part of

the existing GCF to provide for input/output formatting of high-speed

data and wideband data between the MCCC and the CPA, MDA,

and TPA assemblies. It also carried out the function of making

Original Data Records (ODR).

• Digital Instrumentation Subsystem (DIS) to Mark III Interface

(DMI)-A non-minicomputer assembly that provided for the interconnection of the CMF, MDA, and TPA minicomputer assemblies, and

interfaced them with the existing DIS.

• Time Format Assembly (TFA)-A non-minicomputer assembly that

functioned as an extension of the existing Frequency and Timing

Subsystem (FTS) to provide Greenwich Mean Time (GMT) inputs

and various interrupt pulses to the TPA, CPA, MDA, and CMF.

• Data Systems Terminal (DST)-A non-minicomputer assembly that provided a central means of connecting associated Megadata terminals

14

The Viking Era: 1974–1978
(computer monitor displays) and G. E. Terminets (computer input terminals) to any two of up to seven minicomputer assemblies.

Each station-level configuration was designated an “MDS” and was based on the arrang

ment shown in Figure 3-16.

In total, the MDS assemblies and peripherals occupied 214 DSN standard size cabine

assembled into 87 individual modification kits, tested and shipped to the stations f

installation during the 2-year period of implementation.

As Viking conducted important relativity experiments with DSSs 14, 42, and 63, th

MDS implementation activity started at DSSs 12, 44, and 62. As each of these statio

was withdrawn in turn from Viking, Helios, and Pioneer support, the MDS reconfi

uration was carried out and the station was returned to operational status following a

appropriate period of testing and crew retraining.

144

Uplink-Downlink: A History of the Deep Space Networ

Figure 3-16. Basic organization of the Mark III Data System.

EXISTING

GCF

EQUIPMENT

DSS GCF AREA

CMF DMI MDA

CPA

TPA

DSS TRACKING SUBSYSTEM

DSS TELEMETRY SUBSYSTEM

DSS COMMAND SUBSYSTEM

TFA

DST

BCD GMT

BINARY GMT

1 PPS, 10 PPS,

100 PPS, 1K PPS

TO CMF, CPA,

MDA, AND TPA

TO CMF, CPA,

MDA, AND TPA

TO EXISTING

DIS EQUIPMENT
By mid-July 1977, DSSs 12, 14, and 62 had completed system performance testin

in their new configurations and resumed full operational support. Stations 42 an

43 were released from tracking support on July 15, began a ten-week period of reco

figuration and retest, and were returned to operation in mid-October. By the end 

January 1978, the work had been completed at DSSs 61 and 63 and the statio

returned to operations support. The last of the six stations, DSS 11, returned to ser

ice on 26 April 1978.

The accomplishment of this major reconfiguration throughout the entire Networ

in the midst of a heavy and demanding tracking support schedule that included tw

major launches (Voyagers 1 and 2), presented a formidable and exacting task. Th

it was carried out on schedule, without any significant problems, and without impac

ing the ongoing flight support was a credit to all the engineering and operatio

personnel involved.

DSN Mark III-77 Model

At the completion of the MDS implementation task in April 1978, the new DSN mod

Mark III-77 would have all the capabilities needed for support of the remaining m

sions in the Viking Era Mission Set (see Figure 3-1), plus future missions including th

(then-planned) 1983 Galileo mission to Jupiter. These missions include Pioneers 6–1

the Pioneer Venus and Pioneer Multiprobe, Helios, Viking, and Voyager.

The continued growth of the DSN capabilities, in response to flight project requir

ments, is obvious to anyone who examines the key characteristics of the telemetry system

The additional telemetry capabilities resulting from the MDS transformation of the Ma

III-75 model to the Mark III-77 model are listed below:31

1) High-rate X-band telemetry capability (up to 250 kilosymbols per second) at both a 34- and a 64-meter subnet in addition to S-band

telemetry at all subnets.

2) Maximum likelihood decoding (Viterbi algorithm) of short-constraintlength convolutional codes at all DSSs. Deletion of block decoding

after completion of the Viking mission.

3) Replacement of the TCP with a dedicated processor, the TPA, for

telemetry.

14

The Viking Era: 1974–1978
4) Precise measurement of received signal level and system noise temperature.

5) Simultaneous reception of five carriers at a selected DSS for Pioneer

Venus Multiprobe (to be deleted after the mission).

6) Replacement of the Data Decoder Assembly by incorporating its functions into the TPA.

7) Formatting of all decoded data for high-speed or wideband transmission to the NOCC and MCCC via the GCF.

8) Real-time arraying of signals received from two stations at the same

longitude.

DSN Mark III-77 Telemetry System

A simplified block diagram of the telemetry system for the DSN Mark III-75 mod

is shown in Figure 3-17.

Prediction messages are initially generated at the NOCC for transmission by a hig

speed data line (HSDL) to the DSSs for the purpose of establishing the prop

telemetry modes and configurations. Such messages consist of predicted frequencie

data rates, signal levels, and tolerances.

At the DSS, the radio frequency spacecraft signal is collected by the antenna, amp

fied by the Antenna Microwave Subsystem and passed to the Receiver-Exciter subsystem

The radio frequency (RF) carrier is tracked by the receiver, and the telemetry spe

trum is routed to the Subcarrier Demodulation Assembly (SDA) where the subcarri

is regenerated, and the symbol stream is demodulated. The resulting demodulate

symbol stream is passed to the Symbol Synchronizer Assembly (SSA) where it is di

itized. The digitized stream for convolutional encoded data is then routed to th

Maximum Likelihood Convolutional Decoder (MCD) for decoding of short-co

straint-length convolutional codes, or to the TPA for decoding of long-constraint-leng

codes, or uncoded data. The digitized symbol stream for block encoded data is se

to either the TPA or the Block Decoder Assembly (BDA) depending on the da

rate. All the data are formatted by the TPA for transmission by high-speed or wid

band data line to the NOCC and MCCC.

146

Uplink-Downlink: A History of the Deep Space Networ
14

The Viking Era: 1974–1978

Figure 3-17. Functional block diagram of the DSN Mark III-77 Telemetry System. 

ANTENNA

MECHANICAL

SUBSYSTEM

ANTENNA

MICROWAVE

SUBSYSTEM

DSS TEST &

TRAINING

SUBSYSTEM

TESTSIGNALS

CONTROL FROM

DSS MONITOR

& CONTROL

SUBSYSTEM

RECEIVER

ASSEMBLIES

SIGNAL VIA MICROWAVEFROM OTHER DSS REAL-TIME ARRAY

SUBCARRIER

DEMODULATOR

ASSEMBLIES

PRE-POST

DETECTION RECORDING

SUBSYSTEM

NONREAL-TIME

PLAYBACK DSS MONITOR & CONTROL

SUBSYSTEM

PREDICTS

FREQUENCY & TIMING

SUBSYSTEM

RECEIVER-EXCITER SUBSYSTEM

DSS TELEMETRY SUBSYSTEM

SYMBOL

SYNCHRONIZER

ASSEMBLIES

DECODER

ASSEMBLIES

TELEMETRY

PROCESSOR

ASSEMBLY

HIGH-RATE

ODR NOISE TEMP.

SIGNAL LEVEL

STATUS

GCF HIGH-SPEED DATA ANDWIDEBAND SUBSYSTEMS

LOW-RATE

TELEMETRY

DATA &

PARTIAL

STATUS

COMM

MONITOR &

FORMATTER

ASSEMBLY

ERROR

DETECTION &

CORRECTION

ASSEMBLY

ODR

STATION

HIGH-SPEED

DATA

ASSEMBLIES

STATION

WIDEBAND

DATA

ASSEMBLY

CENTRAL

WIDEBAND

DATA

ASSEMBLY

CENTRAL

HIGH-SPEED

DATA

ASSEMBLY

HIGH-SPEED

SWITCH

ASSEMBLY

NETWORK LOG

PROCESSOR

ASSEMBLY

NETWORK

DATA LOG

DATA RECORD

ASSEMBLY

TELEMETRY

IDR

NETWORKDATA PROCESSINGTERMINAL

NC DISPLAY

SUBSYSTEM

NETWORKDATA PROCESSINGAREA

NDPA COMM

PROCESSOR

NC TELEMETRY

SUBSYSTEM

NC SUPPORT

SUBSYSTEM

SYSTEM

PERFORMANCE

RECORD

MCCC AND REMOTE

PROJECT INTERFACE

NETWORK OPERATIONS CONTROL

AREA DISPLAYS AND I/O

WIDEBAND

HIGH SPEED

NOCC GCF DSS

STATUS PREDICTS

TIMING

CONTROL & PARTIALSTATUS

HIGH-RATE TELEMETRYDATA & PARTIALSTATUS
At each DSS, an ODR of the decoded data is written in GCF blocks by either th

TPA for high-rate data or the Communications Monitor and Formatter (CMF) f

low-rate data. The data are passed to a high-speed or wideband buffer dependin

on the data rate, and then transmitted to the MCCC at JPL or in some cases to 

Remote Mission Operations Control Center (RMOC), as in the case of Pione

(ARC) or Helios (GSOC) and, in parallel to the NOCC for network control an

monitoring purposes.

At the NOCC, a limited amount of decommutation of engineering telemetry da

is performed to analyze system performance and to obtain certain spacecraft param

eters useful in controlling the Network. The NOCC also receives and displays DS

Telemetry System parameters.

All the data received by the NOCC either in real time or by recall from the OD

are written to the Network Data Log by the Network Log Processor. The Da

Records Assembly provides for the recall of any missing data by activating the OD

after each station pass to complete the NDL. It uses the NDL as a source to cr

ate the IDR for delivery to the flight project. The IDR is a complete, time-ordere

record of all spacecraft data received at each DSS during a spacecraft tracking pas

DSN Telemetry System performance is displayed and validated in the NOCC by 

comparison of the telemetry system monitor data, which are transmitted from th

DSS, with preset standards and limits for the particular configuration being used

DSN Mark III-77 Command System

In the DSN Mark III-75 Command System model, the DSS command processin

function shared the same computer (XDS-920) as the telemetry processing functio

In the Mark III-77 model, the command function resided in a new dedicated com

puter (MODCOMP II-25) to be known as the CPA. The CPA provided high

reliability, greater processing speed, and more core memory for the command fun

tion. The increased processing speed allowed the DSN to support higher spacecra

command data rates. In the TCP XDS-920, the 8-bits-per-second command bit ra

used by Helios was near the upper limit of the Mark III-75 Command System

Voyager required a command rate of 16 bits per second, and the new CPA wou

accommodate this and even higher bit rates anticipated for future missions.32, 33

Later, in 1978, using the increased data storage capability of the CPA, a new com

mand technique known as “store and forward” was introduced. This technique allowe

148

Uplink-Downlink: A History of the Deep Space Networ
14

The Viking Era: 1974–1978

Figure 3-18. DSN Mark III Command System, 1978.

DEEP SPACESTATIONS (DSS)

NETWORK OPERATIONSCONTROL CENTER (NOCC)

ANTENNAMECHANICALSUBSYSTEM

MICROWAVESUBSYSTEM

TRANSMITTERSUBSYSTEM

TRANSMITTER,EXCITER SWITCHASSEMBLY(ESA)

EXCITER ASSEMBLY

COMMANDSWITCH ASSEMBLY(CSA)

COMMANDMODULATOR ASSEMBLY(CMA)

COMMANDPROCESSOR ASSEMBLY(CPA)

STARSWITCHCONTROLLER(SSC)

COMMUNICATIONSMONITOR &FORMATTER(CMF)

HIGH-SPEEDDATA LINES(HSDL)

ERRORDETECTIONCORRECTION(EDC)

HIGH-SPEEDSWITCH(HSW)

NETWORKLOGPROCESSOR(NLP)

NETWORKCOMMUNICATIONSEQUIPMENT(NCE)

STARSWITCHCONTROLLER(SSC)

EDC HSW NLP NCE

SSC

DISPLAY SUPPORT NCD RTM

NOCCDISPLAYSUBSYSTEM(NDS)

NETWORKSUPPORTCOMPUTER(NSC)

NCD REAL-TIMEMONITOR(RTM)

NETWORKOPERATIONSCONTROLAREA (NOCA)

NETWORK DATAPROCESSINGAREA (NDPA)

JPL MISSION CONTROL ANDCOMPUTING CENTER (MCCC)ARC PIONEER MISIONOPERATIONS CENTER (PMOC)

SPACECRAFTCOMMANDS TO DSS;STATUS FROM DSS

HSDL

HSDL

HSDL CMF

SSC

SHARED STRING

DSS 11,12, 44, 62 (*DSS 12 IS 34-m)

DSS 14DSS 43, 63DSS 42, 61 (*TO BECOME 34-m IN 1980)

SUPPORTSUBSYSTEMSALL STATIONS

SSC

SSC

CMF

HSDL SSC

CPA CMA

CPA CMA

CPA CMA

CPA CMA

CPA CMA

CPA CMA

CPA CMA

BLOCK III

100 kW

20 kW

BLOCK IV

20 kW ESA CSA BLOCK III

400 kW BLOCK IV

20 kW ESA CSA BLOCK III

64-m

26-m μ

WAVE 

μ

WAVE 

64-m μ

WAVE

20 kW 26-m

BLOCK III

μ

WAVE 

FTS DMC

FREQUENCY& TIMINGSUBSYSTEM(FTS)

DSS MONITOR& CONTROLSUBSYSTEM(DMC)

CMF

NOCC COMMAND SUBSYSTEM (NCD)

RECEIVEREXCITERSUBSYSTEM

DSS COMMANDSUBSYSTEM (DCD)

GCF HIGH-SPEED DATA SUBSYSTEM

GCF CENTRALCOMMUNICATIONSTERMINAL (CCT)
the mission operations controllers to prepare large files of spacecraft commands 

advance and then forward them to the DSS at the beginning of a spacecraft trac

ing period. At the DSS, the files were stored on the CPA disk and placed in a queu

for radiation in the specified order at the designated time.

The DSN Command System as it existed after the MDS reconfiguration and su

sequent enhancements is shown in Figure 3-18.

In addition to these improvements, the overall Network command capability w

further enhanced by an increase in the uplink transmitter power at DSS 12 an

DSS 62 from 10 to 20 kilowatts to meet the Network standard. 

DSN Mark III-77 Tracking System

The art of spacecraft navigation is based upon the three types of radiometric da

generated by the DSN Tracking System. The radiometric data types are S- and X

band Doppler, S- and X-band range, and antenna tracking angles. Doppler an

range in various combinations are the most powerful data types, and are used direc

ly in the spacecraft orbit determination process. The Mark III-75 Tracking Syste

had provided these data types for Pioneer, Helios, and Viking. To support Ven

and Voyager, additional new capabilities were needed, and these were provided 

the Mark III-77 model.34

By improving the DSS frequency stability by two orders of magnitude, the ne

Hydrogen maser frequency standards that replaced the older Rubidium frequen

standards extended the precision range and Doppler capability of the DSN Trackin

System to beyond 20 AU to meet the long-range navigation requirements for Voyage

Radiometric data could now be time tagged to the 10-nanosecond level relative 

the DSN master clock.

Calibration of the DSN radiometric data for the effects of the tropospheric an

ionospheric media along the transmission path between spacecraft and Earth w

made possible by a new Meteorological Monitor Assembly that measured these da

at the stations and transmitted them via the new GCF to the Network users.

At the DSSs, all of the old hardware and software associated with the Trackin

System was replaced with new units based on the MODCOMP computers. Th

planetary ranging capability was improved for operation when the line of sight 

the spacecraft passes close to the Sun, and a new unit called the MDA carried o

150

Uplink-Downlink: A History of the Deep Space Networ
all metric data handling functions and controlled the interface with the upgrade

GCF. 

At the NOCC, improvements were made in the generation of tracking data pr

dicts based on a long span of trajectory data supplied by the flight project. Th

display, real-time monitoring, and data validation functions were upgraded to su

plement the DSS and GCF improvements in the Mark III-77 model.

DSN Mark III-77 Ground Communications

For the Mark III-77 model, the GCF capability that provided for transmission 

formatted telemetry data from each DSS to the NOCC and MCCC was also increase

The high-speed data line rate from all stations was increased from 4,800 to 7,20

bits per second. The wideband capacity from each 64-meter DSS in Spain an

Australia was raised from 28.5 to 56 kilobits per second with a capacity of 230 kil

bits per second being available from Goldstone.

End-to-end encoding with new 22-bit error polynomials provided automatic err

detection and correction to significantly reduce the possibility of undetected hig

speed transmission errors. With this correction scheme the DSN was able to approac

nearly 100 percent delivery of real-time data, and cut down on the station time an

personnel effort previously required for post-track replay of missed telemetry dat

These capabilities as they were set up for Viking and the later missions of the Vikin

Era, are shown in Figure 3-19.

In mid-1978, the GCF high-speed-data subsystem was converted from the older lin

switching method of routing messages that had been used for Helios, Viking, an

earlier missions, to programmable message switching capability. The upgrade al

included changes to the NOCC and MCCC interfaces with the GCF. However, th

line switching interface for Viking was maintained until March 1979. By then, me

sage switching was standard for all missions.35

DSN Mark III-77 Arraying Capability

As part of the Mark III-77 capability for Voyager, a two-station arraying capability w

to be provided at each complex. The combining function was to be carried out at th

subcarrier level using the subcarrier spectrum outputs from a 64-meter station and a 3

meter station to provide a single output for telemetry processing. The arraying was 

accommodate subcarrier frequencies of 24 to 500 kilohertz and symbol rates from 2 

15

The Viking Era: 1974–1978
152

Uplink-Downlink: A History of the Deep Space Networ

Figure 3-19. DSN-GCF-NASCOM ground communications, 1976–78.

AUSTRALIA

TIDBINBILLA

DSS 42/432 VOICE3 HSD1 WB

DSS 442 VOICE1HSD

CANBERRANASCOMSWITCHINGCENTER

MADRIDNASCOMSWITCHINGCENTER

NASCOMPROVIDEDCOMMTERMINAL

HSD = HIGH-SPEED DATA

MCCC = MISSION CONTROL AND COMPUTING CENTER

TTY = TELETYPE

WB = WIDEBAND

GCF 20COMMTERMINAL

DSS 112 VOICE1 HSD1 MICROWAVECHANNEL

GOLDSTONE,CALIF

GOLDSTONE,CALIF

DSS 122 VOICE1 HSD

PASADENACA

JPL

DSS 142 VOICE2 HSD2 WB1 MICROWAVECHANNEL

GREENBELTMD

GSFCNASCOMSWITCHINGCENTER

GSFC

VOICE-HSD-TTY-WB

HONEYSUCKLE

SPAIN

JPL, PASADENA

MCCCOPERATIONS/SIMULATIONAREAS

NETWORKOPERATIONSCONTROLCENTER

VK-75MISSIONSUPPORTAREAS

DENVER, COLORADO

VOICE-HSD

DSS 61/632 VOICE3 HSD1 WB

DSS 622 VOICE1 HSD

VIKING 75REMOTE INFORMATIONCENTER1 VOICE1 HSD
250 kilosymbols per second. The combining process was to introduce less than 0.2 dec

bel degradation and to operate at a received signal-to-noise ratio as low as 0.8 decib

from a 64-meter DSS and -5.2 decibels from a 34-meter DSS. This capability wou

find its first operational application as the DSN entered the Voyager Era and the Voyag

spacecraft approached its first encounter with Jupiter.36

DSN Mark III-77 Decoding Capability

To accommodate the decoding requirements of the Viking Era mission set the DSN Ma

III-77 model provided for the following three types of telemetry channel decoding:37

• Viking-Block Codes 32:6; biorthogonal codes handled by the BDA at

the 64-meter DSS at data rates up to 16,000 bits per second. At other

DSS, the block decoding is performed by the TPA software at rates

limited to 2,000 bits per second.

• Pioneers 6–11 and Helios-Long-Constraint Length Convolutional

Codes (32:1/2); Sequential decoding by the Fano algorithm using TPA

software at output rates limited to 4,000 bits per second.

• Pioneer Venus, Voyager, and future missions-Short-Constraint-Length

Convolutional Codes (7:1/2); maximum likelihood decoding by the

Viterbi algorithm using the MCD at output rates up to 250,000 bits

per second.

The block decoding functions for Viking were not substantially affected by the tran

tion to the Mark III-75 model. The long-constraint-length, convolutional decodin

functions for Pioneer and Helios were also essentially unaltered except that they we

now carried out within the TPA by a separate processor that interfaced to the ne

MODCOMP II-25 computers. 

However, the short-constraint-length, convolutional decoding function required b

Pioneer 78, Voyager, and future missions was an entirely new capability. This new decod

was called a Maximum Likelihood Convolutional Decoder (MCD) and utilized th

Viterbi decoding algorithm operating on short-constraint-length codes (K=7) to provi

a gain of about 5 decibels over uncoded data at data rates from 10 to 250,000 bits p

second. The obvious bit rate advantage of maximum likelihood decoding is due to th

fact that a large part of the computations can be performed in parallel, rather than 

sequence, as in sequential decoding.

15

The Viking Era: 1974–1978
The MCD was a special purpose digital computing device that received coded, qua

tized symbols from an SSA and output decoded data to the TPA for formatting an

transmitting to the Mission Control Center at JPL. The functional requirements for th

MCD and the factors used in their selection had been the subject of a great deal 

study, development, test, and evaluation within the DSN for several years prior to the

implementation in the MCD.

The salient features of the MCD are described below:

1) Short-constraint-length (K=7) provided simplified encoder design, adequate decoding performance, and reasonable computational load.

2) Minimum node synchronization time (grouping of incoming symbols

into pairs for rate 1/2 are triplets for rate 1/3).

3) Code rates of 1/2 and 1/3 are provided to satisfy Voyager and provide

growth capability for future requirements. (Note: For a given symbol

rate, rate 1/3 provides about 0.3-decibel improvement over rate 1/2,

but at the expense of reduced data rate.)

4) Maximum data rate of 250,000 bits per second was chosen to be

about double the maximum SSA capability to allow for future increase

in SSA capability.

5) Decoder bit-error rate performance represented a state-of-the-art capability and is given as a function of the ratio of energy-per-bit (Eb) to

noise-spectral-density (No) as shown below:

Energy-per-bit/Noise-spectral Density

Bit-Error Rate Code (7:1/2) Code (7:1/3)

10(-3) 3.0 2.7

10(-4) 3.8 3.5

10(-5) 4.5 4.2

10(-6) 5.2 4.9

154

Uplink-Downlink: A History of the Deep Space Networ
For a comprehensive discussion of the theory and application of telemetry channel enco

ing and decoding by Joseph Yuen, and other experts in that field, the reader is referr

to the book “Deep Space Telecommunications Systems Engineering.”38

The 26-meter Antenna S-X Conversion Project

In consonance with the Mark III-77 project guidelines, a study group was forme

early in 1975 to prepare an implementation plan and budget estimates for upgra

ing the 26-meter antennas to larger diameter and adding an X-band downlin

capability. It was called the 26-Meter S-X Conversion Project. Trade-off studies usin

telecommunication link design parameters for the Pioneer Venus S-band missio

and the Voyager S/X-band mission showed that the optimum diameter for the ne

antennas would be 34 meters. Following a review at NASA Headquarters in Decembe

it was decided that the stations to be modified would be DSS 12, DSS 44, an

DSS 62 and that they would be completed on the following schedule: DSS 1

(Goldstone), 1 December 1978; DSS 44 (Canberra), 1 April 1980; and DSS 6

(Madrid), 1 October 1980.39

The implementation plan issued by N. A. Renzetti on 1 July 1976, called for exte

sive changes in the existing Antenna Mechanical Subsystem, the servo and antenn

pointing control mechanisms, the Antenna Microwave Subsystem, and the Receive

Exciter Subsystem. These changes were to be made on a negotiated schedule 

minimize conflict with the ongoing flight missions.40

The aperture increase from 26-meters to 34-meters required extensive modificatio

of the existing antenna structure. These changes, together with changes to th

microwave elements of the antenna, are shown in Figure 3-20.

The new X-band masers for the 34-meter S/X-band stations would have the sam

basic amplifying portion and cryogenics as the existing operational masers on th

64-meter antennas, but would be provided with superconducting magnets for improv

gain and stability. These X-band masers were also repackaged to make a more com

pact and easily maintained unit, and they were supported by much improve

instrumentation. In particular, the microwave switching control system for the ne

S/X-band waveguide assembly was completely redesigned to be compatible with th

centralized station control and monitoring facilities, and included a graphics displ

of each selectable microwave configuration.41

15

The Viking Era: 1974–1978
The addition of the X-band receive capability at the new 34-meter stations al

required the addition of a fourth harmonic filter to the transmitter subsystem. Th

purpose of the filter was to suppress the fourth harmonic output from the S-ban

transmitter klystron amplifier, which otherwise could cause interference with the X

band signals in the X-band maser receiving pass band.

In order to provide sufficient long-term frequency stability for outer planet navigatio

and potential interferometry applications, an upgrade to the existing 26-meter freque

cy standards was required. For this purpose, two high-grade Cesium standards we

provided, which could be referenced to the hydrogen maser frequency standards at th

nearby 64-meter stations.

156

Uplink-Downlink: A History of the Deep Space Networ

Figure 3-20. Structural changes to the 26-meter antenna for extension to 34-meter diamet

REFLECTOR EXTENSION

REFLECTOR BACKUP STRUCTURE

REINFORCEMENT (WELD JOINTS)

COUNTERWEIGHTS

CABLES, TRAY AND

HYDRAULIC LINES

(RAISE AND ELONGATE)

TO CONTROL ROOM

AREAS OF CHANGE FROM 26-meter

LADDER - EXTENSION

RAISED PEDESTAL

FOUNDATION

COUNTERWEIGHTS

REFLECTOR PANELS NEW

ON EXTENSION

S-X CONE SHELL

DICHROIC

ELLIPSOID

APEX, QUADRIPOD

SUBREFLECTOR

REFLECTOR PANELS - (RESETTING)
The most cost-effective way of providing receivers to complement the X-band maser fro

end was to first down-convert the X-band maser output to S-band, and then feed the 

band signals to the existing Block III S-band receivers. To maintain uplink and downlin

frequency coherence, the reference frequency for the downconverters was obtained throug

appropriate frequency multipliers and dividers from the transmitter-exciter frequency sourc

When completed, the 34-meter S/X-band antennas were required to have the followin

RF performance:

S-band: Transmit: 2,110 (±10) megahertz

Gain: 55.3 (±0.7) decibels

S-band: Receive: 2,285 (±15) megahertz

Gain: 56.1 (+0.3/-0.9) decibels

System Noise Temperature: 

Diplexed, 27.5 (±2.5) degrees kelvin

Listen only, 21.5 (±2.5) degrees kelvin

X-band: Receive: 8,420 (±20) megahertz

Gain: 66.9 (+0.3/-0.9) decibels

System Noise Temperature: 

Diplexed, 25 (±3.0) degrees kelvin

The first station in the series, the Goldstone 26-meter antenna at DSS 12, was decom

mitted from flight project support in June 1978 to undergo the upgrade to 34-met

S/X-band. The work was carried out in the period June through September 1978. Syste

and subsystem tests were conducted at the station, in October 1978, to verify that th

antennas met the design specifications. A period of extensive crew training was follow

by ground data system tests and demonstration tracks on Voyager before being declar

available for full operational support in November 1978. A photograph of DSS 12 aft

its conversion to the 34-meter S/X-band configuration is shown in Figure 3-21.

The large concrete blocks on which the antenna pedestal stands were required to pr

vide sufficient ground clearance for the increased antenna diameter. At the 34-meter sit

in Australia and Spain, large, concrete-lined trenches were formed in front of the ante

nas as an alternative method of providing the necessary ground clearance.

Following the completion of DSS 12, effort on the 26-meter S-X conversion proje

was transferred to the two overseas sites; they were completed in the Voyager Era, b

15

The Viking Era: 1974–1978
by that time the original plan had been changed. Rather than convert the 26-meter st

tions at Cebreros and Honeysuckle as originally planned, the conjoint stations, DSS 4

and DSS 61, were upgraded to 34-meter diameter. DSS 44 and DSS 62 faced an unce

tain future and were eventually retired.

158

Uplink-Downlink: A History of the Deep Space Networ

Figure 3-21. Goldstone Station, DSS 12 antenna after conversion to 34-meter, S-X-ban

Configuration, October 1978.
OVERVIEW

Dominated by Viking and driven by the requirements for tracking and data acquisitio

support for the other major new planetary missions of Helios, Voyager, and the lat

Pioneers, DSN capabilities expanded in the years of the Viking Era, 1974 through 197

Competition between the flight projects for antenna tracking time led to a much mo

formalized approach to forecasting and allocation of these finite DSN resources. Wh

the initial approach left much to be desired, it was continually refined on the basis 

experience and became more effective as time went on. The introduction of a forma

ized architecture for the individual stations of the Network in the form of an integrat

assemblage of interactive systems did much to enhance the manageability of furth

improvements and new implementation in the Network as a whole. The Mark III Da

Systems Project that preceded the Mark III-77 model of the Network is a prime exam

ple. New technology in low-noise X-band receivers, arraying of multiple antennas, an

advanced coding techniques were combined to push the limits of downlink sensitivi

to new levels to match the demands for higher data rates at ever increasing distance

Advances such as these were augmented with improvements to existing resources su

as the conversion of the existing 26-meter antennas to 34-meter diameter and retr

fitting them with X-band receivers.

Although it was not apparent at the time, the launch of the Pioneer multiprobe spac

craft to Venus in December 1978 marked the beginning of the longest hiatus in planeta

spacecraft launchings in the history of NASA. For the next ten years, until the launc

es of Magellan and Galileo in 1989, the DSN would be involved in supporting th

deep space missions already in flight and supporting new and existing Earth-orbitin

missions. It is to these events that we now turn in that period of the history of th

DSN dominated by the remarkable Voyager spacecraft—the Voyager Era.

15

The Viking Era: 1974–1978
Endnotes

1. Edward C. and Linda N. Ezell, On Mars: Exploration of the Red Planet, 1958–197

NASA SP: 4212 (Washington, DC: NASA 1984), p. 452.

2. Jet Propulsion Laboratory, “Deep Space Network to Flight Project Interface Desig

Handbook,” DSN Document Number 810-5, Latest Revision, 1995.

3. D. J. Mudgway and M. R. Traxler, “Tracking and Data Acquisition Support for th

Viking 1975 Mission to Mars,” JPL Technical Memorandum TM 33-783, Vol. I (1

January 1977), pp. 5, 35, 123. 

4. David Morrison and Jane Sanz, Voyage to Jupiter, NASA SP-439 (Washington, DC

NASA, 1980), p. 25.

5. J. E. Allen and H. E. Nance, “Voyager Mission Support,” DSN Progress Report P

42–49, November/December 1978 (15 February 1979), pp. 29–33. 

6. N. A. Renzetti, “A History of the Deep Space Network From Inception to Janua

1969,” JPL Technical Report TR 32-1533 (September 1971), p. 41.

7. William R. Corliss, “A History of the Deep Space Network,” NASA CR-15191

(Washington, DC: NASA, 1976), pp. 92, 194.

8. R. B. Miller, “Pioneer 10 and 11 Mission Support,” DSN Progress Report PR 4

33, March/April 1976 (15 June 1976), pp. 21–25.

9. T. W. Howe, “Pioneer Venus 1978 Mission Support,” DSN Progress Report PR 4

51, March/April 1979 (15 June 1979), pp. 19–30.

10. R. B. Miller, “Pioneer 1978 Venus Mission Support,” DSN Progress Report PR 4

31, November/December 1975 (15 February 1976), pp. 11–14.

11. W. K. Victor, N. A. Renzetti, J. R. Hall, and D. J. Mudgway, “DSN Mark III Da

System Development Plan, Oct-Nov 1969,” presentation given at JP

21 October 1969, Deep Space Network Records, Jet Propulsion Laborato

Archives. 

160

Uplink-Downlink: A History of the Deep Space Networ
12. R. Cargill Hall, Lunar Impact: A History of Project Ranger, NASA History Serie

NASA SP-4210 (Washington, DC: NASA, 1977), pp. 91, 23.

13. M. L. Yeater, “DSN System Requirements: DSN Telemetry System 1977 Throug

1982,” DSN Document 821-2: Rev. B (15 September 1978).

14. D. A. Bathker and D. W. Brown, “Dual Carrier Preparations for Viking,” JP

Technical Report TR 32-1526, Vol. XIV: January/February 1973, (15 April 1973

pp. 178–199.

15. D. A. Bathker and D. W. Brown, “Dual Carrier Preparations for Viking,” JP

Technical Report TR 32-1526, Vol. XIX: November/December 1973, (15 Februa

1974), pp. 186–92.

16. J. R. Paluka, “100Kw X-band Transmitter for FTS,” JPL Technical Report TR 3

1526, Vol. VIII: January/February 1972 (15 April 1972), pp. 94–98.

17. D. J. Mudgway and M. R. Traxler, “Tracking and Data Acquisition Support for th

Viking 1975 Mission to Mars,” JPL Technical Memorandum TM 33-783, Vol. 

(15 March 1977), pp. 94, 125, 137, 208.

18. D. J. Mudgway, “Tracking and Data Acquisition Support for the Viking 197

Mission to Mars; May 1980 to March 1983,” JPL Publication 82-107 (15 M

1983), pp. 3–13.

19. G. S. Downs, R. R. Green, and P.E. Reichley, “A Radar Study of the Backup Martia

Landing Sites,” DSN Progress Report PR 42-36, September/October 1976 (1

December 1976), pp. 49–52.

20. M. A. Gregg and R. B. Kolby, “X-band Radar Development,” DSN Progress Repo

PR 42-20, January/February 1974 (15 April 1974), pp. 44–48.

21. C. P. Wiggins, “X-band Radar Development,” JPL Technical Report TR 32-152

Vol. XII, September/October 1972 (15 December 1972), pp. 19–21. 

22. R. L. Leu, “X-band Radar System,” JPL Technical Report TR 32-1526, Vol. XIX

November/December 1973 (15 October 1973), pp. 77–81.

16

The Viking Era: 1974–1978
23. R. W. Hartop, “X-band Antenna Feed-Cone Assembly,” JPL Technical Report T

32-1526, Vol. XIX: November/December 1973 (15 February 1973), pp. 173–17

24. P. D. Potter, “Improved Dichroic Reflector Design for the 64-m Antenna S-and X

band,” JPL Technical Report TR 32-1526, Vol. XIX: November/December 197

(15 February 1973), pp. 55–62.

25. D. L. Trowbridge, “X-band Travelling Wave Maser Amplifier,” JPL Technical Repo

TR 32-1526, Vol. XVII: July/August 1973 (15 October 1973), pp. 123-30.

26. E. K. Davis, “Mariner Venus/Mercury 1973 Mission Support,” JPL Technic

Report TR 32-1526 Vol. XIV, January/February 1973 (15 April 1973), pp. 5–13

27. D. J. Mudgway and M. R. Traxler, “Tracking and Data Acquisition Support for th

Viking 1975 Mission to Mars,” JPL Technical Memorandum TM 33-783, Vol. I

(1 September 1977), p. 105.

28. M. F. Easterling, “DSN Data System Development Plan, Mark III Project,” DS

Document 803-1, Rev. A (15 March 1974).

29. P. T. Westmoreland, “Technical Requirements Document for DSN Mark III Da

Systems Implementation,” JPL Technical Requirements Document, TRD 338-30

Rev. B (7 February 1975).

30. D. C. Preska, “DSN Standard Practices for Software Implementation,” DS

Progress Report PR 42-29, July/August 1975 (15 October 1975), pp. 119–30. 

31. E. C. Gatz, “DSN Telemetry System Mark III-77,” DSN Progress Report PR 42-4

September/October 1977 (15 December 1977), pp. 4–12.

32. W. G. Stinnett, “Mark III-77 DSN Command System,” DSN Progress Report P

42-37, November/December 1976, (15 February 1977), pp. 4–11.

33. Thorman, H. C., “DSN Command System Mark II-78,” DSN Progress Report P

42-49, November/December 1978 (15 February 1979), pp. 11–18.

34. W. D. Chaney, “DSN Tracking System Mark III-77,” DSN Progress Report PR 4

40, May/June 1977 (15 August 1977), pp. 4–13.

162

Uplink-Downlink: A History of the Deep Space Networ
35. M. S. Glen, “DSN Ground Communications Facility,” DSN Progress Report P

42-36, September/October 1976 (15 December 1976), pp. 4–12.

36. E. C. Gatz, “DSN Telemetry System Mark III-79,” DSN Progress Report PR 42-4

November/December 1978 (15 February 1979), pp. 4–10.

37. J. H. Wilcher, “A New Sequential Decoder for the DSN Telemetry Subsystem

DSN Progress Report PR 42-34, May/June 1976 (15 August 1976), pp. 84–87.

M. E. Alberda, “Implementation of a Maximum Likelihood Decoder in the DSN

DSN Progress Report PR 42-37, November/December 1976 (15 February 1977

pp. 176–83.

J. W. Layland, “Convolutional Coding Results for the MVM 1973 X-ban

Telemetry Experiment,” DSN Progress Report PR 42-48, September/October 197

(15 December 1978), pp. 18–21.

38. Joseph H. Yuen, “Deep Space Telecommunications Systems Engineering,” JP

Publication 82-76, Jet Propulsion Laboratory, California Institute of Technolog

(July 1982), pp. 220–47.

39. V. B. Lobb, “26-meter S-X Conversion Project,” DSN Progress Report PR 42-3

March/April 1977 (15 June 1977), pp. 157–67.

40. N. A. Renzetti, “DSN Data System Development Plan, 26-meter S-X Conversio

Project,” DSN Document 803-7 (1 July 1976).

41. H. R. Buchanan, “S-X 34-meter Conversion Receiver and Microwave Performance

DSN Progress Report PR 42-50, January/February 1979 (15 April 1979), p

219–25.

16

The Viking Era: 1974–1978
CHAPTER 

The Voyager Era: 1977–1986

16
THE VOYAGER ERA 

From the overall DSN point of view, the transition from the Viking Era to the Voyag

Era was not marked by a clearly defined change in activity or objectives. Rather, dri

en by the press of real-time mission events, the focus of DSN attention merged gradual

from Viking-related matters to those of Voyager.

It began with the successful launches of two large planetary spacecraft in 1977 and 197

For almost the next decade, the two Voyager spacecraft repeatedly astonished the wor

with a flood of dazzling science data and images as they transmitted their data fro

Jupiter, Saturn, and Uranus. At the same time, many other inflight missions vied wi

Voyager for the support of the tracking stations of the Deep Space Network. The appea

ance of a new class of mission, the Earth Orbiters, to the DSN “inventory” furth

complicated the situation in this period.

DSN resources were stretched to the limit, not only by the number of simultaneo

missions but by the requirements for new and enhanced capabilities to support the mu

tiplicity of missions and the ever-extending uplinks and downlinks from the two Voyage

For the purpose of giving an account of DSN history between the Voyager launches 

1977 and the first appearance of Galileo in 1986, this period may be identified as th

Voyager Era, and it is to this era that we now turn our attention.

The scale of Network activity during the Voyager Era is best appreciated in the conte

of the Deep Space and Earth-orbiting missions which were then of concern to the DSN

The chart shown in Figure 4-1 depicts the situation.

This workload, together with engineering and implementation of upgrades to the cap

bilities of the Network, is the subject of the discussion that follows.

Deep Space Missions

Except for the activity associated with the receiver problem on Voyager 2, the Voyag

launches and early cruise events in 1977 and 1978 were “nominal.” DSN Operatio

resources were dominated more by the multiple spacecraft requirements of the Vikin

mission and the complexities of the Pioneer Venus missions during that period. Th

Mark III Data System (MDS) implementation effort, together with the start of the 2

m to 34-m antenna upgrade and the S/X-band conversion tasks, fully occupied DS

engineering and implementation personnel.

166

Uplink-Downlink: A History of the Deep Space Networ
However, by the beginning of 1979, the focus of DSN attention was rapidly changin

The Mark III Data System implementation task had been completed, the new capab

ities required for the Voyager Jupiter Encounter were in operation throughout the Networ

and operations teams were trained in their use. The Viking mission had been extend

through May 1978 and then further continued through February 1979. Both Pione

Venus missions had been successfully completed in 1978, and both Voyager spacecra

were approaching Jupiter and were expected to carry out a full program of science expe

16

The Voyager Era: 1977–1986

Figure 4-1. Voyager Era Deep Space mission set, 1977–86. Each of the vertical bars in th

chart represents a deep space or Earth Orbiter mission which was in the DSN “inventory” duri

the Voyager Era. During the period shown on the vertical scale, all missions passed through va

ous phases of their lives. Future missions were in the planning stage, primary missions were 

flight, and secondary missions had already completed their primary missions and were being track

by the DSN stations on a lower priority basis as “extended missions.” The number and phase 

the missions in any year represents the relative level of activity in the Network at that particu

time. For example, from mid-1977 through 1980, the Network handled five, and for a short tim

six, primary missions simultaneously with four secondary missions and three missions, includi

Earth Orbiters, in the planning stages.

Voyager Era

Deep Space Network Mission Set

1987

1986

1985

1984

1983

1982

1981

1980

1979

1978

1977

P6-9 P10 He1 Vk1 Vk2 He2 Vg2 Vg1 P12 Pm/p Ulys GII HEO VB-P

Secondary Missions

Future Missions

Primary Missions

Voyager Era
iments and imaging sequences during their brief encounters with the planet in Mar

and July 1979.

For approximately two years, the Voyagers moved along separate trajectories to equal

spectacular and scientifically rewarding encounters with Saturn in 1980 and 1981. Fro

there, Voyager 2 would be retargeted to Uranus for an encounter in 1986, leaving Voyag

1 to continue along an inevitable path toward the outer reaches of the solar system. A

Uranus, Voyager 2, because of its remarkable longevity, would be retargeted yet again—

this time for an encounter with Neptune in 1989.

For their success, each of the Voyager encounters depended not only upon operab

spacecraft, but also upon ever greater significant enhancement of the uplink and dow

link DSN capabilities of the Network. At the same time, a heavy expenditure of DS

operational resources in personnel, training, and facilities was required simply to mai

tain a viable science data return from existing missions.

As the mission set in Figure 4-1 clearly shows, there were as many as ten inflight, de

space missions throughout the solar system, supported at various times during this perio

A closer look at the chart also shows that there were no new planetary launches aft

the Pioneer Venus missions in 1978. To a large extent this hiatus was due to debat

within NASA about the objectives and funding for the Lunar spaceflight progra

using the Space Shuttle, and the robotic space exploration programs using expendab

launch vehicles.1

Galileo was the new flight project most affected by this situation. As the vertical bar 

Figure 4-1 shows, Galileo remained in “new mission” status for ten years. Between 197

when the original plan for a 1982 launch was approved, and 1987, when the final pla

for a launch in 1989 was approved, the Galileo launch vehicle was changed four time

Each change to the launch vehicle necessitated a complete redesign of the mission wi

corresponding changes to the requirements for tracking and data acquisition suppo

With each change, the DSN responded with a plan for new or modified capabiliti

and schedules. Change was the name of the Galileo game in those years.2

The Ulysses mission also remained in a state of suspension during the Voyager Er

Ulysses was a joint NASA/ESA mission to study the poles of the Sun and interplan

tary space both above and below. As part of the joint effort, NASA had committed 

Shuttle launch to ESA for the purpose of deploying the Ulysses spacecraft into Ear

orbit. From there, Ulysses would use a solid motor Inertial Upper Stage (IUS) to inje

168

Uplink-Downlink: A History of the Deep Space Networ
it into a trajectory toward Jupiter. The gravitational field of Jupiter would redirect Ulyss

out of the plane of the ecliptic and into a heliocentric orbit passing over the poles 

the Sun. First planned for launch in 1983, Ulysses finally made it to the launch pad 

October 1990 after two postponements, one in 1983 and one in 1986. The design 

the mission and its requirements on the DSN were not affected by the delays in th

Shuttle program.

Toward the end of the Voyager Era, a truly international cooperative mission made 

appearance. The Venus-Balloon mission in mid-1985 involved the Soviet, French, an

United States space agencies. Although of very short duration, it presented a compl

engineering and operational challenge for the DSN. Its successful completion establish

a basis for future relationships between these agencies in the area of tracking and da

acquisition support for deep space missions.

Earth-Orbiting Missions

The DSN began the Networks Consolidation Program, which expanded the cap

bility of DSN tracking and data acquisition support to include support for high-Ear

orbiting (HEO) missions as distinct from Deep Space (DS) missions in 1980. HE

missions were defined to be those which were beyond the capability of the new

developed NASA space network called the Tracking and Data Relay Satellite Syste

(TDRSS). The HEO class of missions would have orbits with an apogee in exce

of 12,000 km, and would be supported by the 26-m and 9-m networks added 

the DSN as part of the Networks Consolidation Program. Mainly through the pe

sistent efforts of W. R. Martin, this criterion was eventually modified to allow th

DSN to provide support, in the near-Earth region below 12,000 km, for a who

new class of non-NASA missions known as “reimbursables.” Under the reimbursab

arrangement with NASA, foreign space agencies were able to employ the services 

the DSN for part or all of their missions, subject to compliance with DSN techn

cal and resource conditions. NASA would be reimbursed at a standard hourly ra

for the antenna time provided to the foreign space agency. Within a few years, th

term “HEO” fell out of common usage and became simply “Earth Orbiter (EO)

to include these latter missions.

DSN support for Earth-orbiting missions began in 1984 with ICE (International Cometa

Explorer). Under a different name, ICE had been placed into a heliocentric orbit by 

Delta launch vehicle in 1978. As a cooperative mission with ESA, it was to monit

solar phenomena. Later, the name was changed to ICE and its orbit was changed 

encounter the Comet Giacobini-Zinner in September 1985. It was soon joined by th

16

The Voyager Era: 1977–1986
Active Magnetospheric Particle Explorer (AMPTE) series of missions. Designed to stud

the transfer of mass from the solar wind to the magnetosphere from an Earth orb

above 100,000 km, these missions were also a cooperative effort between NASA, th

United Kingdom, and the Federal Republic of Germany.

DSN support for ICE and AMPTE continued through the entire Voyager Era, su

ported a number of short duration reimbursable missions, and reached a peak 

thirteen in 1985.

Since 1984, support for Earth-orbiting missions in the form of cooperative, reimbursab

or NASA projects has become a permanent feature of the DSN purpose in the Unit

States space program.

170

Uplink-Downlink: A History of the Deep Space Networ
NETWORK OPERATIONS

Prime Missions

Voyager at Jupiter

The Voyager Project was the ultimate realization of a much earlier NASA plan to sen

two robotic spacecraft to visit all of the outer planets of the solar system in the lat

years of the 1970s. As early as 1969, even as Congress was approving funds for the fir

exploratory missions to Jupiter (Pioneers 10, 11), NASA was making grand plans f

future planetary exploration.

Based on a report from the United States National Academy of Sciences, which foun

that “exceptionally favorable astronomical opportunities occur in the late 1970s for mu

tiplanet missions,” this “mother of all missions” came to be known as the Grand Tou

An additional report, published in 1971, concluded with a specific recommendatio

“that Mariner-class spacecraft be developed and used in Grand Tour missions for th

exploration of the outer planets in a series of four launches in the late 1970s.” At lea

in theory, this unique juxtaposition of the planets would allow a passing spacecraft 

use the gravitational pull of one planet to alter its trajectory in such a way as to red

rect it toward a flyby of the next planet. The process could be repeated, as required, 

make a complete tour of all the outer planets. The technical challenges of such a m

sion were enormous. Amongst them were precise celestial navigation and deep spa

communications, both primary functions of the DSN.

In its original form, the NASA plan for the Grand Tour encompassed dual launches 

Jupiter, Saturn, and Pluto in 1976 and 1977, and dual launches to Jupiter, Uranus, an

Neptune in 1979. A total cost, over the decade, was about $750 million.3 Later, how

ever, political and budgetary constraints forced NASA to scale back the original plan 

two missions to Jupiter and Saturn, with an option for an encounter with Uranus. Th

total cost of the new missions was to be $250 million, a more acceptable figure in th

fiscal climate of the early 1970s.

Congressional approval was soon forthcoming and the official start of the Voyager m

sion was set for 1 July 1972. NASA designated JPL as the Lead Center and Edward C

Stone, a distinguished expert on magnetophysics from Caltech, as Project Scientist. Becau

the new mission was based on the proven, JPL-designed Mariner spacecraft, it was in

tially named MJS, for Mariner Jupiter-Saturn; the name became Voyager in 1977 b

most of the early documentation retained the original name. At JPL, Raymond L. Heaco

17

The Voyager Era: 1977–1986
became Project Manager with Richard P. Laeser as his Mission Director, and Esker K

Davis as Tracking and Data Systems Manager, representing the DSN. Although the

names changed several times as the mission progressed over the next twenty-five yea

the functions always remained the same.

In both concept and execution, the Voyager Project was one of the most ambitious pla

etary space endeavors ever undertaken. The Voyager 1 spacecraft was to investigate Jupit

and several of its large satellites, and Saturn and its rings and large satellite, Titan. Voyag

2 was also to observe Jupiter and Saturn and several of their satellites after which it w

to be redirected toward an encounter with Uranus in 1986. After their final encou

ters, both spacecraft would eventually cross the boundary of the solar system into interstell

space. Each spacecraft would carry instrumentation for conducting eleven scientific inve

tigations in the fields of imaging science, infrared radiation, ultraviolet spectroscop

photopolarimetry, planetary radio astronomy, magnetic fields, plasma particles, plasm

waves, low energy charged particles, cosmic ray particles, and radio science. A new onboa

computer system gave the Voyagers greater independence from ground controllers an

more versatility in carrying out complex sequences of engineering and scientific oper

tions than on the Mariners earlier.

On each spacecraft, uplink communications with the DSN were provided by two 

band radio receivers while downlink communications used four 25-watt transmitte

two of which operated at S-band and two at X-band. Each spacecraft carried a larg

3.7-meter diameter, high-gain antenna (HGA) in addition to a smaller, low-gain ante

na intended for use as backup. Combined with the HGA, the X-band downlink w

designed to deliver telemetry data up to 115.4 kilobits per second to the DSN 64-

antennas from the distance of Jupiter.

That was the plan and the basis for the Voyager project requirements for DSN trac

ing and data acquisition support for the first part of the overall mission—namely th

launch phase, cruise phase, and with the Jupiter Encounter.4 The Network respond

to these requirements with the DSN MDS. The MDS and the events associated wi

the Voyager launch and cruise phases marked the closing stages of the Viking Era. Even

associated with the approach of the two Voyager spacecraft to Jupiter, toward the en

of 1978, soon showed that transition to the Voyager Era had already begun.

As the year 1979 opened, the space drama unfolding at JPL and featuring Voyager 1 

Jupiter had begun to attract the attention of space scientists and observers througho

the world. Excerpts from “Voyage to Jupiter”5 describe the mounting interest. “In mi

January, photos of Jupiter were already being praised for ‘showing exceptional details 

172

Uplink-Downlink: A History of the Deep Space Networ
the planet’s multicolored bands of clouds.’” “By early February, Jupiter loomed too lar

in the narrow-angle camera to be photographed in one piece.” Sets of pictures call

mosaics were necessary to cover the entire planet body. A spectacular movie coverin

ten Jupiter days and displaying the swirling vortices of the upper atmosphere would 

assembled from thousands of images transmitted from the spacecraft as it approach

the planet. These images, transmitted at the rate of about one image per 90 secon

over the X-band downlink at 117 kilobits per second, required 100 hours of contin

ous DSN coverage to complete.

The Voyager 1 spacecraft reached its point of closest approach to Jupiter at 4:42 a.m

PST, on 5 March 1979, at a distance of 350,000 km from the planet center and 66

million km from Earth. The governor of California was present at JPL, and a spec

TV monitor was set up in the White House for President Carter to witness this h

toric event. A short time before the closest approach to Jupiter, Voyager had begun a

intensive sequence of observations of Io. Much of the data, taken during the Canber

pass, was stored on the spacecraft tape recorder and played back later over the Goldston

stations so that it could immediately be transmitted to JPL.

Typical examples of the many images of Jupiter and Io taken by Voyager 1 are show

in Figures 4-2 and 4-3.

The passage of Voyager 1 through the Jupiter system is shown in Figure 4-4.

The entire event, from the time it crossed the orbit of Callisto inbound to the time 

recrossed it outbound, took only 48 hours. In that short time, equal to two comple

passes around the DSN, Voyager made observations on a major planet, Jupiter, and fi

of its satellites—Amalthea, Io, Europa, Ganymede, and Callisto. Never before had 

planetary encounter yielded such a wealth of new and unique scientific data. It was tru

a major milestone in the history of planetary exploration. In his essay, “Voyager: Th

Grand Tour of Big Science,”6 Andrew Butrica noted, “Voyager is planetary exploratio

on a grand scale.” The mission was only just beginning.

As Voyager 1 receded from Jupiter, it continued to work through the carefully plann

post-encounter mission sequences, and accelerated on to a new trajectory that took 

to an encounter with Saturn in November 1980.

Voyager 2, four months behind Voyager 1, moved into the Jupiter observatory phase an

took imaging sequences for another time-lapse movie and activated its UV and fiel

and particles instruments.

17

The Voyager Era: 1977–1986
For the next several months, DSN operations activity would be dominated by these tw

high profile planetary missions. Voyager 1 post-encounter activities were kept at a lo

level so that the majority of the support facilities could be devoted to preparation f

the Voyager 2 encounter. The Doppler tracking loop problem in the Voyager 2 rad

receiver complicated each DSN tracking pass by requiring a continuous change in th

uplink frequency to compensate for the Doppler shift at the spacecraft. This chan

could now be predicted and included in the computer driven predicts, but it was al

necessary to monitor the spacecraft telemetry to detect any drift in receiver rest fr

quency and modify these predicts in real time to maintain the spacecraft receiver in loc

174

Uplink-Downlink: A History of the Deep Space Networ

Figure 4-2. Voyager 1 image of Jupiter, 13 February 1979, at a distance of 20 million kilom

ters, showing Io (left) and Europa (right) against the Jupiter cloud tops. One of the most spectacu

planetary photographs ever taken was obtained on 13 February 1979, as Voyager 1 continued 

approach Jupiter. By that time, at a range of 20 million kilometers, Jupiter loomed too large to 

within a single narrow-angle imaging frame. Passing in front of the planet are the two Galilean sat

lites. Io, on the left, already shows brightly colored patterns on its surface, while Europa, on the rig

is a bland, ice-covered world. The scale of all of these objects is huge by terrestrial standards. Io a

Europa are each the size of our Moon, and the Great Red Spot is larger than Earth.
Despite these difficulties, all transmitted command sequences were accepted by the spac

craft, and uplink and downlink communications were maintained successfully.

As Voyager 2 closed with Jupiter, the returning images showed clear evidence of the gre

changes that had taken place in the Jovian atmosphere since the Voyager 1 encounter 

March. In passing through the Jupiter system, Voyager 2 would be able to fly by th

same satellites as Voyager 1. It would “see” different faces of Callisto and Ganymede an

pass much closer to Europa and Ganymede. Unfortunately, it would pass much furth

away from the volcanic satellite Io. Although it was not realized at the time, the da

from the closer pass to Europa and the further pass from Io would be of great signi

cance when the Galileo spacecraft returned to Jupiter seventeen years later. Some of th

Voyager sequences were changed as a result of the Voyager 1 experience, but in gener

they followed the same pattern.

The Jupiter Encounter occurred at 3:29 p.m. PDT, on 9 July 1979, amid great excit

ment as new data on the satellites and the planet itself poured in and were released 

17

The Voyager Era: 1977–1986

Figure 4-3. Voyager 1 image of Io, 4 March 1979. Taken at a distance of 400,000 kilomete

the picture shows the giant volcano Pele and strangely colored deposits of surface material.
the public in the daily press conferences. A new satellite of Jupiter, Andastra, was d

covered and a ring quite unlike those of Saturn was observed for the first time. Th

NASA Associate Administrator for Science, Thomas A. Mutch, was moved to rema

that “such events are clearly read into the record. And I submit to you that when th

history books are written a hundred years from now . . . the historians are going to ci

this particular period of exploration as a turning point in our cultural, our scientif

our intellectual development.”7

During and after the encounter, there was some concern about the effects of the Jupit

radiation environment on the spacecraft radio receiver. This caused more rapid drift 

frequency than expected and actually resulted in loss of the uplink connection with th

spacecraft on the day after encounter. By sending repeated commands at various fr

quencies, the DSN operators were finally able to find a frequency at which the spacecra

receiver would accept the commands, just in time for the commands needed to fire th

thrusters for the trajectory correction maneuver that would enable the spacecraft to ma

the turn for Saturn.

176

Uplink-Downlink: A History of the Deep Space Networ

Figure 4-4. Voyager 1 trajectory through the Jupiter system, 5 March 1979.

Launch date = 9/5/77

Jupiter arrival date = 3/5/79

Earth

occultation Sun

occultation

Voyager 1 trajectory

Satellite closest approach

Io

Periapsis

Amalthea

2 hr

Europa

Callisto

Ganymede
While Voyager 2 added considerably to the volume of science delivered by Voyager 1, 

also added to the number of unanswered questions about the “King of Planets.” Th

answers would be a goal for Galileo, the next Jupiter mission, which lay many years 

the future. At that time, however, the next exciting goal for both Voyagers lay less tha

two years away. It was the planet Saturn.

The demand for contiguous support for Voyager and the Pioneer Venus Orbiter in 197

had forced the DSN to consider economies in the use of tracking station time for pr

track preparation, i.e., the configuration and calibration of the station hardware an

software needed for an upcoming spacecraft tracking pass. Prior to this time, the DS

had generally been able to assign a complete station to a flight project in a critic

encounter phase, to the exclusion of all other users. In this situation pretrack prepar

tion times of as much as six to eight hours were normally used. Time needed for essent

station maintenance consumed additional time. Early in 1979 this was no longer po

sible because of end to end Voyager and Pioneer view periods of 8 to 10 hours each 

the same 64-m sites. To contend with this situation, DSN operations devised a ne

strategy for pretrack preparation. Pretrack and post-track activities for both spacecra

were drastically shortened and carried out during a single allocated time period.8 “Qui

turnaround” reduced the time allowed between the end of one track and the start 

the next to the time required to reposition the antenna and to mount new tapes. 

addition, time for routine station maintenance was based on a new formula which ensur

an essential, monthly minimum number of hours for each type of antenna.

From this time on, the DSN was under constant pressure to increase the amount 

tracking time available for flight project use, often at the expense of reducing or eve

eliminating, essential maintenance time with consequent risk to station reliability. Ov

the years, the basic rules devised in 1979 for allocation of pretrack and post-track prep

ration time have served the DSN well in striking a balance between conflicting deman

for maximum antenna tracking time and maximum station reliability.

Voyager at Saturn

In terms of uplink and downlink capability, the requirements of the Voyager missio

to Jupiter had been met by the DSN Mark III-77 Data System described in detail 

the previous chapter. In fact, several years earlier, the Voyager requirements for telem

try, command, and radiometric data had been one of the principal drivers for that maj

upgrade to the Network capability and the schedule on which it was carried out (s

chapter 2). When completed in April 1978, it provided the Voyager missions with a

X-band, high-rate (up to 115 kilobits per second) telemetry downlink at Jupiter ran

17

The Voyager Era: 1977–1986
from all three 64-m stations. Radiometric products, in the form of two-way Doppl

and ranging data, provided for precise navigation and the S-band, 20-kilowatt, tran

mitters were more than adequate for command purposes at Jupiter range.

However, to support the Voyager spacecraft at Saturn, double the range of Jupiter, an

possibly even Uranus, four times the Jupiter range, substantial enhancements to the Ma

III-77 capability, particularly in the detection of weak signals, were required. Becau

the downlink signal strength diminishes as the square of the spacecraft distance fro

Earth, the signals reaching the DSN antennas when the spacecraft reached Saturn wou

be only one-fourth of those received from Jupiter, one-fourth less again when the spac

craft reached Uranus.9

These and other issues related to DSN operational support for Voyager were routin

topics on the agenda of the weekly Voyager project meetings at JPL. Led by the pro

ect manager or the mission director, project meetings were the established JPL foru

for negotiation of all requirements and interactions between the DSN and all flight pro

ect organizations. Once the actual mission began, the agenda of the regular proje

meetings was expanded in scope (and duration) to include status and progress repor

ing, as well as future requirements on the DSN. The meetings comprised representativ

from each of the institutional organizations involved with that particular flight projec

of which the DSN was one. Marvin R. Traxler represented the DSN to the Voyag

project. The DSN appointed similar representatives to each of the flight projects to spe

on DSN matters.

It should be pointed out that negotiations between the flight projects and the DSN

which involved the design and implementation of new DSN capabilities, were com

pleted as much as five years prior to the “time of need,” due to the long lead tim

required for the DSN approval, funding, contractual, implementation, testing, and ope

ational training processes. In some cases, even five years proved to be insufficient tim

That is the reason for the long planning periods represented by future missions in th

charts of the DSN mission sets for the various eras (see Figure 4-1 for the Voyager Era

A formal set of top level documentation conveyed the project “requirements” and th

DSN “commitments” to the two Program Offices at NASA Headquarters, the Office 

Space Science (OSS) and Tracking and Data Acquisition (OTDA), for formal, top-lev

approval. Lower tier documents within the project and the DSN disseminated the ne

essary technical and operational detail to the implementing organizations. These ste

infrequently occurred in serial fashion. Rather, driven by the always-pressing flight pro

ect schedules, work proceeded on the assumption that the necessary formalities wou

be eventually completed. Interactions between the flight projects and the DSN were ite

178

Uplink-Downlink: A History of the Deep Space Networ
ative in nature; as space communications technology advanced, the technical requir

ments of deep space missions advanced to justify the implementation of the new technolo

in the Network, and vice versa.

Such was the case for Voyager. Even as the two Voyager spacecraft left their launch pa

bound for Jupiter in 1977, engineers in Robertson Stevens’s Telecommunications Divisio

at JPL had turned their attention and considerable talents to the enhancements th

would be needed for the existing Network capabilities to support the Voyager spacecra

if and when they reached Saturn, Uranus, or even Neptune. Of course these enhanc

ments would benefit all deep space missions; NASA insisted that they be multimissio

in nature, and so they were, although they were generally attributed to the first missio

to make use of them.

Ultimately, the flight project requirements that had been approved for implementatio

in the Network were published in the form of a plan, jointly signed by project an

DSN representatives. The referenced DSN Preparation Plan for Voyager is typical 

those prepared for all flight projects which used the Network at various times.10

The final plan to meet the Voyager project requirements for DSN support of the tw

Saturn encounters included the addition of major new or improved capabilities, to th

existing Network, in the following technical areas:

1. S-band and X-band antennas: Capability to receive both S-band and X-band dow

links at three 34-m stations and three 64-m stations. All 64-m antennas were optimiz

with X-band, low-noise masers for improved downlink performance, and with sp

cial microwave feeds for radio science experiments during encounter.

2. Downlink signal enhancement: Two-station arraying at each Complex using the 34-

and 64-m antennas and the Real-Time Combiners to improve the signal margin b

about 1.0 dB (approximately 25 percent) compared to the 64-m antenna alone. Th

would allow the downlink telemetry rate to run as high as 44.8 kilobits per second

3. Precision navigation: Up to six different kinds of radiometric data to enhance spac

craft navigation and radio science experiments by allowing for the removal of charg

particle effects in the interplanetary media. These data types consisted of vario

combinations of S-band and X-band Doppler and ranging data. Besides basic improv

ments in the accuracy of the ranging system, the DSN Tracking System also includ

automatic uplink frequency tuning to compensate for the failed frequency trackin

loop in the Voyager 2 transponder.

17

The Voyager Era: 1977–1986
4. Radio science augmentation: New precision powered monitors, spectrum signal ind

cators, open-loop receivers and multiple-channel, wideband, digital recorders togeth

with appropriate software were installed at DSS 63 Madrid, the prime radio sc

ence station designated by Voyager for covering the occultation and Saturn rin

experiments during the Voyager 1 encounter. Later, some of this equipment w

moved to the Canberra site and installed at DSS 43 to cover the Voyager 2 encount

This equipment measured changes to the inherent radio frequency characteristi

(polarization, phase delay, spectral spreading, scintillation, etc.) of the Voyager rad

signal as it grazed the Saturn atmosphere or passed through the rings. Later anal

sis of wideband recordings of these data provided significant new scientific data o

the composition of the atmosphere and the structure of the rings.

The manner in which this work, together with other project-related activity, was carri

out during the Voyager Era is described in a later section on Network engineering an

implementation.

Following their highly successful encounters with Jupiter in 1979, both Voyager spac

craft commenced the Jupiter-Saturn cruise phase of the mission. The Saturn trajectori

had been established as the spacecraft passed Jupiter and, in the months that followe

both spacecraft carried out routine engineering, science, test, and calibration activitie

While these routine activities were in progress, the spacecraft carried out a number 

special activities.

In February 1980, a delicate cruise science maneuver, which involved turning the spac

craft away from the Earth pointing direction, was performed. The maneuver went w

and the spacecraft reacquired the uplink after the antenna came back to Earth poin

The scan platform was calibrated in March, and the Canopus star tracker sensitivity w

checked in April. Numerous navigation cycles were carried out to refine the radiome

ric data used for spacecraft orbit determination. A navigation cycle consists of on

continuous uninterrupted pass around the Network. Radiometric data, consisting 

Doppler, ranging, and a new data type called Delta Differential One-way Ranging (Delt

DOR), are generated by each of the participating stations in turn, as the spacecraft pass

through each longitude.

While the real-time operations elements of the Network were supporting all of the

Voyager related activities, other parts of the DSN operations organization were also bus

preparing for the upcoming Saturn Encounter.

180

Uplink-Downlink: A History of the Deep Space Networ
In March 1980, operations and engineering representatives from the stations in Spa

and Australia arrived at Goldstone for training in the installation and operation of 

new device called a Real-Time Combiner (RTC). The RTC enabled the signals fro

two or more separate antennas to be combined electronically to produce a single ou

put of considerably greater strength than either of the input signals alone. When us

in this manner, the antennas were said to be arrayed. The RTC had been used earli

in a two-station array at Goldstone during the Voyager 2 Jupiter Encounter, with encou

aging results. The X-band downlink signals from the DSS 14, 64-m antenna had bee

combined with the signals from the new DSS 12, 34-m antenna to give a telemetry si

nal gain of 1.1 dB relative to the 64-m antenna alone. This result, obtained und

real-time operational conditions, agreed well with the theoretical, predicted value of 1

(±0.2) dB. There was great interest in adding a similar capability at the two other 6

m sites where the 26-m to 34-m antenna upgrades were just being completed. Aft

completing the classroom courses and receiving operations experience, the trainees wou

return to their home sites to replicate the Goldstone installations.

The overseas sites, Deep Space Station 42 (DSS 42) in Australia and DSS 61 in Spai

were being requalified for operational support following the upgrade of their antenn

from 26-meter to 34-meter diameter. In May, DSS 14 (Goldstone) and DSS 62 (Spai

were returned to operational status after requalification following antenna downtime f

replacement of the subreflector at DSS 14 and repair of the antenna drive gear box

at DSS 62.

All of the DSN upgrades and modifications to hardware planned for the Voyager Satu

Encounter had been completed and declared operational by mid-1980. In addition, seve

new software packages needed for the antenna, communications, command, radiome

ric, meteorological, occultation, and planetary ranging systems were installed througho

the Network and certified for operational use. The DSN was ready for the first Voyag

Saturn Encounter.11

Voyager 1 began its concentrated observations of Saturn on 22 August 1980, just 82 da

before its closest approach to the ringed planet. At that time, the spacecraft was trave

ling with a heliocentric velocity of 45,675 miles per hour, at a distance of 67.6 millio

miles from the planet. The radio signals from the DSN antennas were taking 80 mi

utes to travel the distance of 901 million miles from Earth to the Voyager spacecraft.1

The DSN began a series of navigation cycles around the Network to provide preci

orbit determination data on which the spacecraft Navigation Team would base the param

eters for the final trajectory correction maneuver to fly close by, but not impact, Tita

18

The Voyager Era: 1977–1986
In addition, the unique geometry of the Saturn Encounter, zero declination, requir

highly accurate ranging measurements from two stations simultaneously to provide radi

metric data from which the declination of the spacecraft orbit could be determined. 

Earlier, the spacecraft had experienced some minor hardware problems in the Canop

star tracker and the scan platform supporting the cameras, but neither was expected 

pose a serious problem to the planned Saturn Encounter activities.

The Canopus star tracker helped stabilize the spacecraft and keep it properly orient

by tracking Earth, the Sun, and a reference star, normally Canopus. A backup star trac

er was available for use if needed. The scan platform supported the imaging camer

and other science instruments, and under certain conditions of operation had shown 

slow drift which could be compensated for, if necessary.

By making use of the 28 percent gain in downlink signal power that would result fro

using the DSN 34-m and 64-m antennas in the arrayed mode at all three complexe

the Voyager mission controllers planned to run the spacecraft downlink at a telemet

data rate of 44.8 kilobits per second. Without arraying, the maximum data rate pos

ble from Saturn would have been only 29.9 kilobits per second. By contrast, the da

rate at the Jupiter Encounter had been 115.2 kilobits per second due to the much shor

er spacecraft to Earth range of 413 million miles.

The onboard planetary radio astronomy experiment had been used to determine the rot

tion rate of Saturn with greater precision than was possible with Earth-based measuremen

and cyclical bursts of nonthermal radio noise had been detected. Daily scans of the pla

et by the ultraviolet spectroscopy instrument were searching for hydrogen sources, an

fields and particles instruments were constantly monitoring the interplanetary mediu

near Saturn. Hundreds of photographs were being taken by the imaging system to com

pile a full color “time-lapse” movie as the Voyager spacecraft zoomed in on the plane

One of the spectacular pictures from this period is shown in Figure 4-5. At the time th

picture was taken, Voyager 1 was 80 days from Saturn Encounter at a distance of 66 m

lion miles. In addition to the planet itself, three satellites could be seen, and the inn

and outer rings, separated by Cassini’s division, were clearly visible. The imaging data w

transmitted from the spacecraft over DSS 43 at a data rate of 44.8 kilobits per secon

Before the spacecraft reached Saturn, it passed behind the Sun as viewed from Eart

During this period of solar conjunction, from 3 September through 6 October, the ang

defined by the Sun, Earth, and Voyager became 15 degrees or less, and the radio noi

emitted by the Sun gradually degraded the radio downlink to the DSN tracking st

182

Uplink-Downlink: A History of the Deep Space Networ
tions. However, these conditions provided a unique opportunity for the radio astron

my observations of the Sun and heliosphere as the radio signals from the spacecra

passed through the solar corona. At each of the Deep Space Communications Complexe

the radio science equipment had been upgraded with new and improved hardware an

software in anticipation of these imminent events.

Following the solar conjunction period, the uplink and downlink performance return

to normal as the spacecraft continued to rapidly approach the planet.

By 24 October, 19 days before encounter, the field of view of the narrow angle came

could no longer cover Saturn in one frame. It took four pictures to image the enti

planet. Ten days later, the Saturn image was larger still and more mosaic pictures we

needed to cover it. Attention was then focussed on more detailed examination of th

18

The Voyager Era: 1977–1986

Figure 4-5. Voyager 1 image of Saturn and its rings, August 1980. Taken on 24 August 198

80 days before closest approach at a distance of 66 million miles, this image shows the Saturni

satellites Enceladus, Dione, and Tethys.
planetary features. The extraordinarily complex structure of the Saturn ring system w

shown in a mosaic of two images taken on 6 November from a distance of 4.9 millio

miles. (See Figure 4-6.)

On 11 November 1980, twenty-six hours before reaching the point of closest approa

to the planet, the spacecraft began executing the encounter sequences which had bee

preprogrammed into its onboard computers months earlier. Downlink telemetry rat

varied between 19.2 kbps and 44.8 kbps as the spacecraft automatically switched throug

various formats to return imaging, general science, and playback data in rapid succe

sion. Taking high-resolution pictures as it went, the spacecraft would first pass clo

(7,000 km) by the haze-covered satellite Titan before dipping below the ring plane 

it accelerated toward the point of closest approach. Eighteen hours later, on 12 Novemb

1980, Voyager 1 reached its closest point to Saturn, 184,000 km from the center an

124,000 km above the cloudtops of the shadowed southern hemisphere.

184

Uplink-Downlink: A History of the Deep Space Networ

Figure 4-6. Voyager 1 image of Saturn and its rings, November 1980, shows approximate

95 individual concentric rings.
Some 100 minutes after closest approach, the spacecraft passed behind Saturn and remain

obscured from Earth for 90 minutes. During this time, and at entrance and exit fro

occultation, DSS 43 and DSS 63 carried out valuable radio science measurements rela

ed to an understanding of the structure and composition of the Saturn atmosphere an

ionosphere. At this point the radio signal from the spacecraft was taking four and on

half hours to reach the Earth-bound antennas of the DSN.

Voyager 1 continued to observe the planet and its satellites through December 15, 

which time the Saturn post-encounter phase ended and a new phase of scientific da

collection began. For as long as the DSN could maintain an uplink and a downlin

with the spacecraft it would continue to observe the planetary medium, participating 

celestial mechanics and solar experiments with other spacecraft travelling through th

solar system. It was now on a solar system escape trajectory that would take it out 

the plane of the ecliptic, the plane of Earth’s orbit around the Sun. Someday, Voyag

1 and other planetary spacecraft will reach the heliopause, the outer edge of the sol

system. The DSN will continue to track these spacecraft, each going in a different dire

tion to try to determine the size of this invisible region of our solar system. It w

expected that Voyager 1 would cross the heliopause in about ten years, 1990, at a d

tance of 40 AU.13

Voyager 1 had completed its primary mission of planetary exploration. There were n

other planets along its new path nor could its path be changed even if there wer

Eventually, it would exit the solar system altogether, climb above the ecliptic towar

the constellation Ophiacus, and chase but never catch it for all time.

The attention of the Voyager project returned to Voyager 2, now seven months aw

from its encounter with Saturn in August 1981.

During the encounter phase of the Voyager 1 mission, the mission operations activi

on Voyager 2 had been relatively quiet, with most of the DSN tracking support bein

provided by the 26-m network, while Voyager 1 dominated the 64-m and 34-m ne

works. Beginning in February 1981, however, the pace on Voyager 2 picked up as th

DSN raced to complete several major new capabilities needed to support the Voyager 

Saturn Encounter.

The equipment used for the Voyager 1 radio science observations had to be moved fro

DSS 63 in Spain to DSS 43 in Australia, the prime viewing site for Voyager 2 solar co

junction. This equipment, which included the four-channel narrow band and wide ban

receivers and associated digital recording assemblies, had to be integrated with new so

18

The Voyager Era: 1977–1986
ware in the Occultation Data Assembly and tested while operational procedures we

developed and crew training progressed in parallel.

The receiver problem on Voyager 2, described earlier, had now become a “fact of lif

with which the DSN had to deal. To this end, the DSN had developed new softwa

to automatically control the Digitally Controlled Oscillator (DCO) which drives the fr

quency of the uplink transmitter. The DCO would be programmed to compensate f

the inability of the Voyager 2 spacecraft receiver to acquire and track the uplink fr

quency transmitted by the DSSs, because of its failed tracking loop. It would reside 

the Metric Data Assembly (MDA).

There was, however, a complication introduced by spacecraft internal temperature chang

It had been determined that various spacecraft activities would cause compartment tem

perature changes, which would in turn cause the center frequency of the spacecra

receiver to drift in an unpredictable manner. This would make it very difficult or impo

sible for the DSN to set the transmitter frequency to the exact Best Lock Frequen

(BLF) needed to track the spacecraft receiver. To provide background data on the fr

quency offset and drift caused by spacecraft temperature variations, the DSN had bee

supporting a special tracking procedure known as “adaptive tracking.” In an “adapti

tracking” sequence, the 34-/64-m station carries out a series of uplink frequency ram

estimated to pass through the BLF. By observing the spacecraft receiver reaction to th

uplink frequency ramps, a real-time determination of the correct value of the BLF an

its drift can be made. These data can then be used to program the DCO to keep th

uplink frequency centered in the slowly drifting receiver pass band.

The DSN would need to use “adaptive tracking” during the Voyager 2 Near Encount

period to ensure rapid and reliable acquisition of the spacecraft receiver for uplink com

mand purposes. The key to this new capability was the new MDA software which dro

the DCO.

This software was installed at all sites by midyear. After the operations crews were train

in its use, it was verified for encounter operations by conducting demonstration trac

with the live spacecraft.

Early in 1981, the DSS 12 antenna, upgraded to 34-m in time for the Jupiter Encount

was decommitted from support operations for six weeks for further upgrade work 

improve its radio efficiency. The two outer rows of antenna surface panels were replac

and reset, and the subreflector surface was replaced with one designed for better ill

mination of the primary antenna. The controller for the subreflector was also upgrade

186

Uplink-Downlink: A History of the Deep Space Networ
The net result of this work was an improvement of 0.7 dB in antenna gain, demo

strated on the first operational pass when the antenna returned to service in April. Th

DSS 12/14 array would also benefit during encounter operations.

On 5 June 1981, the observation phase of the Voyager 2 Saturn Encounter began. Th

first activity was the movie sequence, which started over the Madrid Complex with De

Space Stations 61 and 63 (DSS 61 and DSS 63) tracking the spacecraft, and was co

cluded on 7 June over the Canberra Complex with tracking support by DSS 42 an

DSS 43. During the movie phase, the arrayed 34-/64-m configuration was used at 

complexes to enhance the received imaging telemetry data. The performance of th

arrayed stations was well within the predicted tolerances and resulted in excellent pi

ture data quality.

While the spacecraft team conducted a sequence of scientific observations somewhat sim

ilar to those conducted by Voyager 1, the DSN completed the remaining hardware an

software items needed for encounter, and enhanced the proficiency of the DSS crew

with Operational Verification Tests.

Beginning with the passes over DSS 61 and DSS 63 on 13 August, and continuin

around the Network for several days, high rate imaging data were obtained by the DSN

The 34-m and 64-m stations were arrayed for this support and the real-time data we

received at 44.8 kbps with playback data at 29.8 kbps. These images, which were take

under better lighting conditions and at a better approach angle than had been possib

on Voyager 1, were later used by the project to compile a Saturn rings movie.

A final pre-encounter trajectory correction maneuver on 18 August was supported ov

DSS 12 and DSS 14. During the maneuver sequence, the spacecraft antenna was plac

off Earth point for over an hour resulting in loss of the downlink for that time. DS

14 reacquired at the proper time and the telemetry data indicated that the trajecto

correction had been performed correctly.

In preparation for the extensive radio science activities which would occur over DSS 4

during this encounter, a final radio science Operational Readiness Test was conduct

with the Canberra Complex on 19 and 20 August. All of the encounter equipment w

operational, and the actual operational sequence was used for the test. With the su

cessful completion of this test, the DSN was declared ready to support the secon

Voyager encounter of Saturn.14

18

The Voyager Era: 1977–1986
The Near Encounter Mission phase started on 25 August 1981. Recording of celest

mechanics data in the form of closed-loop Doppler and ranging data had begun ear

er and was continued through the encounter period. High-rate imaging data of th

closest approach sequences from the narrow-angle camera was obtained at 44.8 kbps 

the arrayed mode. Image reception in the arrayed configuration was excellent and n

images were lost due to DSN operations. With most of its Saturn observations com

pleted, Voyager 2 passed within 63,000 miles (101,000 km) of the Saturn cloudtops, 

9.50 p.m. (Earth Received Time), 25 August 1981. Still to come were observations 

the dark side of the planet and southern hemisphere, the underside of the rings, an

several satellites.

Shortly after 10 p.m. PDT, the imaging sequence ended and the spacecraft began to d

appear behind the disk of Saturn. For the next 90 minutes, it would remain occult

by the planet. As it entered occultation, and again as it exited, the DSN radio scien

System at DSS 43 recorded open-loop and closed-loop receiver data. The data wou

yield information regarding the Saturn atmosphere and ionosphere and the microwav

scattering properties of the rings.

When the spacecraft exited occultation and the DSS 43 downlink was reestablishe

telemetry data indicated that the scan platform had not carried out its programm

pointing sequences while it was behind the planet. Only black sky image frames we

being received. Playback of the tape recorder data from the spacecraft indicated th

the scan platform had functioned properly while the spacecraft was occulted and th

fault had occurred just prior to egress. Investigation of the problem by the proje

resulted in restoration of the scan platform capability some days later and the Satu

imaging sequences resumed. Throughout all of this action, the DSN continued to pr

vide Network support and accommodate numerous schedule and sequence changes 

the situation required.

A trajectory correction maneuver on 29 September refined the Voyager 2 flight path 

Uranus with a swing-by assist toward Neptune.

Preliminary science results from Voyager 2 revealed that subtle changes had taken pla

in the Saturn atmosphere since the Voyager 1 visit nine months earlier. Voyager 2 sa

more detail in the atmosphere and much more detail in the rings, which could be num

bered in the thousands. Voyager 2’s trajectory took it on a wide arc through Saturn

magnetic field, exploring different regions and adding to the data obtained by Pione

11 and Voyager 1. On its passage through the Saturn system, Voyager 2 passed closer 

188

Uplink-Downlink: A History of the Deep Space Networ
some of the satellites, further away from others, than did Voyager 1, and it returned 

magnificent set of images of the planet and all its major satellites.

DSN support of the Voyager 2 Near Encounter activities at Saturn was accomplish

without any significant problems. Radio science played a major part of the encount

operations at DSS 43. During the closest approach period, DSS 43 generated 10 med

um-band and 40 wide-band Digital Original Data Records (DODRs) for radio scienc

These were used to produce 484 radio science intermediate data records (IDRs). A

DSN Near Encounter operations were conducted in the arrayed mode. The quality 

telemetry imaging data was excellent and no images were lost. 

Even with the scan platform problem, it was considered that the Voyager Saturn m

sion objectives had been met.

The DSN contributed to this success in two most significant ways. First, the successf

operational use of “adaptive tracking” mode enabled the DSN to accommodate th

uplink problems created by the failed spacecraft receiver tracking circuit, and secon

the excellent performance of the Network in using the “arrayed” configuration to enhan

the downlink performance to the point where 44.8 kbps real-time telemetry data 

Saturn range became a reality for the first time ever.

By the end of August 1981, Voyager 2 had completed nearly half of its three-billio

mile journey to Uranus, measured from the launch in August 1977 to Uranus Encount

in January 1986. Then four years old, the spacecraft was in good condition except f

the radio receiver problem discussed above and some difficulty with the scan platfor

pointing sequences which stuck, shortly after closest approach to Saturn on 25 Augu

Since then, the anomaly had been thoroughly analyzed and understood, and the sca

platform had been maneuvered successfully several times. Prospects for a successful Uran

Encounter appeared to be good.

Nevertheless, at the final press conference for the Saturn 2 Encounter, several of th

speakers, including Ed Stone, the Imaging Team Leader, and Bruce Murray, the JP

Director, reminded those present of the long hiatus in deep space missions that l

ahead. It would be five years before the DSN would see the launch of another de

space mission, and that would be Galileo—or so they thought.

18

The Voyager Era: 1977–1986
Venus Balloon/Pathfinder

In the period between 1983 and 1985, as international relations between the Sovi

Union and the United States began to improve, the first signs of scientific collaboratio

in space-related endeavors appeared in the form of a cooperative project involving sc

entists of the Soviet, French, and American space agencies. It would be called call

Venus Balloon/Pathfinder. As Bruce Murray observed, “This technical partnersh

between the United States, Europe, and Russia came about despite the absence of an

formal relations between NASA and the Soviet Union. The original U.S.-USSR bila

eral space agreements of 1972 (which facilitated, among other endeavors, the Apollo-Soy

handshake in space in 1975) expired in 1982. Renewal became a casualty of U.S. ho

tility to the USSR, triggered by the Soviets’ suppression of the Solidarity movement 

Poland and their invasion of Afghanistan.”15

On 11 and 15 June 1985, the Soviet VEGA 1 and VEGA 2 spacecraft released tw

instrumented balloons into the atmosphere of Venus. The VEGA spacecraft continu

past the planet on their way to a rendezvous with Comet Halley in March 1986. Driftin

with the Venus winds at an altitude of about 54 km, the balloons travelled one-thi

of the way around the planet during their 46-hour lifetimes. Sensors carried by the ba

loons made periodic measurements of atmospheric pressure and temperature, vertic

wind velocity, cloud particle density, ambient light level, and frequency of lightning. Th

data were transmitted to Earth and received at the DSN 64-m antennas and at sever

large antennas in the USSR. Approximately 95 percent of the telemetry data were su

cessfully decoded at the DSN complexes and in the Soviet Union, and were provid

to the international science community for analysis.16 These data would supplement cu

rent knowledge of the Venus atmosphere obtained by earlier Soviet Venera spacecra

and the NASA Pioneer Venus Probes.

Ground-based tracking support for the Venus balloon experiment involved an intern

tional network of about a dozen radio astronomy antennas organized by the Fren

space agency, CNES, a more limited internal Soviet Network and the three 64-m ante

nas of NASA’s Deep Space Network.17

Consequent upon the negotiation of appropriate diplomatic and technical agreemen

in Moscow, Paris, and Washington, the DSN managers determined the trajectories 

both the VEGA 1 and 2 bus spacecraft during the Venus flyby phase to recover telem

try from the balloon signal and, as part of the international network, to acquire VLB

data from each balloon/bus pair while the two were within the same antenna beamwidt

190

Uplink-Downlink: A History of the Deep Space Networ
To meet these commitments, the DSN would employ, as far as possible, existing cap

bilities normally used for planetary spacecraft navigation, radio science, and radio astronom

However, there were some special requirements connected with the Soviet spacecraft’s 

band downlink and telemetry system.

To deal with the downlink, JPL engineers designed, built, and installed L-band fee

horns and low noise amplifiers at all three 64-m antennas. An L-band to S-ban

frequency-up converter provided an S-band signal spectrum to the radio science an

receiver-exciter subsystems for subsequent extraction and recording of telemetry spectr

one-way Doppler and the essential DDOR and very long baseline interferometry (VLB

data. The telemetry system was not so straightforward. The peculiarities of the Ven

Balloon telemetry system required the development of special software to extract th

telemetry data burst from an open-loop recording of the L-band spectrum transmitt

by the balloon. Owing to the somewhat unusual nature of this mission, the normal JP

software development resources were not available to the DSN which had, therefore, 

seek help elsewhere. The necessary help and expertise needed to produce the softwa

came from Spain in the form of a software development team led by Jose M. Ure

and the engineering staff of the Madrid complex.18

Jose M. Urech was director of the Madrid Deep Space Communications Complex 

Robledo from 1981 until his retirement in 1999. Prior to becoming Director, he h

served for fifteen years as servo engineer and station analyst for NASA’s 26-m station 

Cerebros near Robledo. At retirement, he had been associated with NASA tracking st

tions as a foreign national for thirty-three years.

Dr. Urech had roots in Madrid, Spain, and was educated in both Spain and France pri

to earning a doctorate in engineering from the Polytechnic University of Spain in 1969

Quiet-spoken, courteous, and low-key in manner, with a partiality for good food an

wine, he engendered confidence in all who dealt with him, at whatever level, in NAS

business. His social graces, technical ability, and leadership skills were of great help 

integrating his team of Spanish engineers into the American-oriented methodology 

the space program, and in minimizing the inevitable effect of cultural differences 

resolving issues that occasionally arose between the two.

In addition to carrying out his management responsibilities, Jose Urech made time 

pursue his technical interests. In 1969 and 1970, he first developed and demonstrat

the concept of combining the output of two antennas to improve telemetry receptio

This experiment, the first of its kind in the DSN, arrayed two antennas, 20 km apa

19

The Voyager Era: 1977–1986
to enhance the downlink signal from Pioneer 8. In 1985, Jose Urech led a team of eng

neers from the Madrid station in the development of the special software needed 

process the telemetry signals from the Venus Balloon mission. He also contributed 

that mission by coordinating the various technical efforts of participants from JPL/NASA

CNES (France), and IKI (USSR).

Throughout his career, Urech was highly regarded by JPL as a valuable consultant an

additional resource that could be, and frequently was, called upon to address technic

questions related to the performance and productivity of the tracking stations.

He retired from NASA/INTA in 1999 to pursue his interests in active outdoor activ

ties, music, and science, and to assist his wife with her business ventures.

The success of the Venus Balloon experiment depended on two new, very precise orb

determination techniques—Delta differential one-way ranging (DDOR), which was us

for the Voyager planetary spacecraft navigation by the DSN, and the VLBI, which w

used by radio astronomers for determining the position of extra-galactic radio source

The DSN would use DDOR and one-way Doppler techniques to determine the ma

spacecraft (bus) trajectory, for a two-week period, around the time of Venus flyby. Balloo

position and velocity would be obtained from VLBI measurements between the ma

spacecraft and the balloon, taken by an international network of ground-based rad

astronomy antennas, which included the three 64-m antennas of the DSN, over a pe

od of approximately two days near each Venus Encounter, when both bus and balloo

were in the same DSN antenna beamwidth.

The DDOR navigation technique employed by the DSN for very precise determin

tion of spacecraft orbits required a measurement on a nearby extra-galactic radio sour

(EGRS). To find EGRS suitable for VEGA orbit determination, the DSN first had 

make measurements of the L-band correlated flux density of 44 potential EGRS take

from the existing JPL radio source catalog of 2.3 GHz and 8.4 GHz sources.19

During the actual encounter period, the DSN performance in all three areas of suppo

was satisfactory. Balloon telemetry data obtained by the DSN were provided to the sc

ence teams on computer-compatible magnetic tape in the form of original record

spectra and in the form of demodulated and decoded data streams. Most of the deco

ed telemetry data was provided from MDSCC where Spanish engineers succeeded 

adaptively adjusting their data processing software to compensate for the totally une

192

Uplink-Downlink: A History of the Deep Space Networ
pected wind conditions on Venus that created Doppler rates up to fifty times great

than the predicted values on which the software designs were based.

Only seven of the ninety-two balloon telemetry transmissions were missed, mainly d

to downlink signal variations caused by the balloon itself.20

During the fifteen-day period of Venus Encounter observations, the DSN succeeded 

obtaining good DDOR data on 85 percent of the attempts. These data formed the ba

for the VEGA flyby orbit determination. The DSN also obtained good VLBI data o

sixty-seven of the sixty-nine balloon transmissions. These data, in conjunction with th

VEGA orbit data, were used to estimate balloon position and velocity. 

The end of the Venus Balloon experiment did not, however, spell the end of DS

involvement with the two VEGA spacecraft. Nine months later, in early 1986, the DS

would again be providing DDOR data from the VEGA spacecraft in support of Pathfind

operations for the Giotto mission to Comet Halley.

DSN support for these missions took place as the DSN moved into the Galileo E

described in the next chapter.

Voyager at Uranus

The Downlink Problem

As the excitement associated with the successful Saturn encounters in 1980 and 198

subsided and the two Voyager spacecraft began to move along their new trajectorie

Voyager 1 toward the edge of the solar system and Voyager 2 toward Uranus, the Voyag

Project and the DSN began negotiations for even more enhanced tracking and da

acquisition support than that provided for Saturn. At a distance of 20 AU from Eart

double the range of Saturn, with the downlink signal correspondingly reduced to 2

percent of its strength, the Voyager requirements for Uranus posed a further challen

to the ingenuity, innovation, and expertise of JPL’s Telecommunication Division, whi

provided engineering support to the DSN. Basically, the problem was that of compe

sating for the loss of downlink due to increased spacecraft range (at Uranus) with increas

signal gathering capability on the ground.

In the early 1980s, the DSN had adequate technical capability to support the planeta

missions then in the mission set, at distances of 5 to 10 times the Earth-Sun distanc

5 to 10 Astronomical Units (AU). It was not until the successful Saturn Encounter 

19

The Voyager Era: 1977–1986
August 1981 that a Uranus Encounter at 20 AU in 1986 became a real possibility. Th

DSN antennas did not then have the additional 4 to 6 dB of downlink capability th

would be required to support the desired imaging data rate from Voyager 2 at the d

tance of Uranus.21

The NASA planetary program was entering the hiatus period of the 1980s and, other tha

Voyager 2 at Uranus and possibly Neptune, there were no future missions in view th

would justify additional, large, new antennas. However, earlier DSN studies had draw

attention to the significant improvement in downlink performance that could be obtain

from an array of existing antennas.22 Furthermore, it was (theoretically) possible, by th

use of data compression techniques in the spacecraft, to increase the efficiency of th

telemetry data stream itself. By combining the improvements derived from DSN arrayin

with the improvements resulting from spacecraft data compression, the downlink cap

bility required to obtain the desired science data return at Uranus could be realized.

Voyager 2 at Uranus in 1986 could not be regarded as merely a five-year extension 

the 1981 Voyager Jupiter-Saturn mission, for it was indeed a new mission from a DS

point of view. It had been renamed the Voyager Uranus Interstellar Mission.

To this end, a comprehensive study of DSN options for employing arraying techniqu

to enhance DSN downlink performance for Voyager encounters of Uranus and pos

bly Neptune was undertaken in 1982. The study was not limited to DSN antennas an

therefore included a survey of all known large antenna facilities, including those 

Australia, England, Germany, Japan, Italy, and Russia. The “Interagency Array Stud

Team was led by J. W. Layland and published its recommendations in April 1983.23

In considering arrangements for interagency arraying, the study recommended that pe

manent ties should be sought with other space agencies such as Japan’s Institute f

Space and Aeronautical Science (ISAS), but that for shorter term goals, such as suppo

of Voyager at Uranus, a radio astronomy observatory seemed more appropriate. In th

context, the array of the Canberra Deep Space Communications Complex (CDSCC

with the 64-m antenna of the Australian Commonwealth Scientific and Industrial Resear

Organisation (CSIRO) radio astronomy observatory at Parkes, New South Wales, w

recommended as most viable DSN configuration for support of the Voyager at Uranu

A photograph of the 64-m antenna of the CSIRO radio astronomy observatory at Parke

New South Wales, Australia, is shown in Figure 4-7.

194

Uplink-Downlink: A History of the Deep Space Networ
The downlink performance of all the DSN arrayed complexes and the enhanceme

that would be provided by the addition of the Parkes antenna to the CDSCC array 

shown in Figure 4-8, which is taken from this study.

In addressing the specific needs of Voyager at Uranus, the study had started with th

Voyager project requirement for an imaging science data return of 330 full frame imag

per day, with about 30 to 50 images per day in the few months preceding encount

Coupled with this requirement was a possible improvement in the efficiency of the spac

craft telemetry data transmission system resulting from the use of new coding and da

compression techniques in the spacecraft Flight Data Systems. The new spacecraft cap

bility would be implemented by inflight reprogramming of the two redundant Flig

Data System processors to function as a dual parallel data processor. This enabled th

spacecraft to transmit the science telemetry at lower data rates than would otherwi

have been possible.

19

The Voyager Era: 1977–1986

Figure 4-7. Parkes 64-m radio astronomy antenna.
An assessment of the imaging science data return resulting from this new spacecraft cap

bility and the link performance shown in Figure 4-19 concluded that the combin

capability of all three DSN complexes, supplemented at CDSCC with the Parkes Antenn

would be able to return 320 full frame images per day under optimum conditions.

Although there were some qualifications to that estimate relating to spacecraft tape record

strategy and telecommunications link uncertainties, these were understood and accep

ed. The requirement was very close to being satisfied in a feasible and cost-effective wa

196

Uplink-Downlink: A History of the Deep Space Networ

Figure 4-8. Enhanced link performance for Voyager 2 at Uranus. The figure predicts how t

telemetry data downlink between the Voyager spacecraft at Uranus and the DSN antennas on Ea

would vary as Earth rotated. The vertical scales depict the maximum sustainable rates at whi

science data could be transmitted over the downlink (right) with their equivalent signal-to-no

ratios (left). The rotation of Earth is represented on the horizontal scale in terms of GMT. The low

curves represent the situation for arrayed antennas at each of the DSN sites in Goldstone, Californ

Canberra, Australia; and Madrid, Spain. The upper-center curve shows the greatly enhanced pe

formance that would result from coupling the DSN arrayed antennas at Canberra with the Australi

radio astronomy antenna at Parkes.

GDSCC +

PARKES

GDSCC

64, 34, 34

CDSCC

64, 34, 34

MDSCC

64, 34

29.9

21.6

19.2

14.4

8.4

7.2

19 20 00 04 08 12

GMT HOURS

DATA RATE - 

KILOBITS / SEC

90% CONFIDENCE

PD/NO,

DB Hz

49

48

47

46

45

44

43

42

41

40
and planning to support Voyager at Uranus with each Complex fully arrayed with on

64-m and two 34-m antennas (only one 34-m at Madrid) supplemented with the 6

m antenna at Parkes, went forward.

This would be the first time that interagency support had been provided for a maj

planetary encounter, and as such the Parkes-Canberra Telemetry Array (PCTA) wou

be a “pathfinder” for further applications of this technology. And much sooner than w

foreseen at the time, interagency arraying would become established as an alternate resour

for DSN support of many NASA and non-NASA deep space missions.

It would be a busy time for Director Tom Reid and his staff engineers as impleme

tation of the PCTA and preparations for the Voyager Uranus Encounter played o

simultaneously at the Canberra Complex. Nevertheless, it was a situation Reid had exp

rienced on several occasions in the past. In fact, most of the major expansion of th

tracking facilities at the Canberra Deep Space Communication Complex (CDSCC), 

Tidbinbilla near Canberra, took place during Tom Reid’s directorship of the Comple

In that eighteen-year period, the 64-m antenna was built and later increased in size 

70 m; the 26-m antenna was enhanced to 34 m; a new, high-efficiency, 34-m antenn

was built; and X-band uplinks and downlinks were added. Their successful integratio

into the Network and subsequent record of outstanding service to NASA spaceflig

programs owed much to his cooperation.

A native of Scotland and an electrical engineering graduate of the University of Glasgo

Reid served in both the Royal Navy and the Australian Navy before taking charge 

telemetry services for the Australian Weapons Research Establishment’s rocket test ran

at Woomera in 1957. His association with NASA began in 1963 with radar support f

the Gemini program, at the Red Lake site near Woomera. In 1964 he took charge 

the NASA tracking station at Orroral Valley, moved to Honeysuckle Creek in 1967, an

in 1970 he was appointed to succeed R. A. Leslie as Director of the Tidbinbilla Statio

His crisp management style and penchant for clear lines of authority, particularly in h

relations with JPL and NASA personnel, made a visit to “his” Complex a memorab

experience for many Americans. He ran the station in a disciplined, formally organiz

way that attracted and retained the best technical staff available. As a direct result 

their teamwork and his leadership, the CDSCC played a critical role in all of NAS

deep space missions in the years 1970 to 1988.

At the time of his retirement in 1988, his wife, Margaret, represented the Australia

Capital Territory as a senator in the Australian Parliament.

19

The Voyager Era: 1977–1986
The design and operational use of the arraying system would be based on the succes

ful demonstration of arraying techniques in a DSN operational environment that h

been observed during the Jupiter and Saturn encounters, and the additional new DS

capabilities that were becoming available as part of the Mark IVA implementation effo

Unlike the DSN antennas, which were colocated at each Complex, the Parkes antenn

was some 280 kilometers CDSCC. In addition, it required completely new receivin

and telemetry equipment to make it compatible with the Voyager downlink. The desig

and implementation of the PCTA was a joint effort of JPL, CSIRO, and the Europea

Space Agency (ESA).24 ESA became involved because of an existing arrangement wi

CSIRO to support an ESA mission to Comet Halley called Giotto, in 1987, short

after the Voyager Uranus Encounter.

In summary, CSIRO was to provide a new feedhorn and antenna with upgraded su

face for X-band operation, ESA was to provide the X-band maser and down convert

and JPL was to provide an interfacing microwave assembly, 300-MHz receiver, forma

ting and recording equipment and a baseband data interface to the 280-km intersi

microwave link supplied by the Australian Department of Science.

Together, these facilities provided the critical elements of a real-time combining syste

similar to that used at Goldstone for the Saturn Encounter with DSS 14 and DSS 1

However, in this case a special, long-baseline, baseband combiner would be required 

CDSCC to compensate for the much longer delay on the baseband signal path betwee

Parkes and CDSCC. At CDSCC, baseband signals from DSS 14, DSS 42, and DS

45 would be combined first, before being combined with the Parkes baseband signal 

the long-baseline combiner. In addition, the new Mark IVA monitor and control fac

ities provided greatly improved conditions for correctly operating these very compl

configurations in a critical real-time environment. A functional block diagram of th

Parkes-CDSCC telemetry array configuration is shown in Figure 4-9.

Because of the critical role of CDSCC and Parkes in the Uranus Encounter strateg

both sites were provided with pairs of Mark IVA digital recorders to back-up the rea

time system with baseband recordings, at both sites.

Arrangements at the Goldstone and Madrid complexes were similar, but simpler. A

Goldstone, the baseband signals from DSS 14 and the two 34-m antennas, DSS 12 an

DSS 15, were combined in the new Mark IVA Baseband Assembly (BBA) which, 

addition to the baseband combining function, carried out the functions of subcarri

demodulation and symbol synchronization. These two latter functions had been carri

198

Uplink-Downlink: A History of the Deep Space Networ
19

The Voyager Era: 1977–1986

Figure 4-9. Functional block diagram of the Parkes-CDSCC telemetry array for Voyager Uranus Encounter, January 1986.

64 m

FRONTEND

RECEIVER

34 m

FRONTEND

RECEIVER

34 m

MARK IVA DEN

ESA PARKES

PCTA CDSCC

PCTA PARKES

TESTSIGNAL

ESA PARKES

CSIRO PARKES

CSIRO PARKES PCTA PARKES

OPERTERM

ARRAYCONTROLLER

BBINTERFACE

BB SIGNALS

BBINTERFACE

TEST SIGNALS

ARRAYCONTROLLER

OPERTERM

OPERTERM FTS

TSA TO CDSCC FEA’S

DSA 1

DSA 2

DSA 2

BBA 1

DSA 1

MCD/TPA

BBA2

MCD/TPA

PARKESCDSCCDATA•SNR•CDSCCDATA•SNR

PARKESSNR

VOICE

DATA

300 MHzRECEIVER

CONVANDFORMATTER

MARK III DATMARK III DAT

BBCOMBINER

RT

LONGBASELINEBBCOMBINER

RT

FORMATTER

DEFORMATTERDEFORMATTER

NRTNRT

DEFORMATTERDEFORMATTER

TELECOM PCTA CDSCC

FREQUENCY AND TIMING

MARK IVA DSN

ANT.SERVO

RCVD CARRIER LEVELS

FREQUENCY AND TIMING

FACILITIES

POINTING PREDICTSPOINTING STATUS

FRONTEND

RECEIVER

64 m

FEED DUAL TWMS DOWN CONVS

B8 TEST SIGNALS

SYSTEM TEMP

CONFIG INDIC

YFACTOR
out by separate assemblies in the former Mark III system. At Madrid the array consis

ed of just the 64-m antenna and the 34-m standard antenna at DSS 61.

In addition to its downlink capability, a further item of great concern in connectio

with the Uranus Encounter was the pointing capability of the DSN antennas.25 To avo

degrading the downlink signal from the spacecraft significantly, it was determined th

the DSN antennas must be pointed to less than 0.16 of the antenna half-power beamwidt

This corresponded to less than six one-thousandths (6/1,000) of a degree or 6 millid

grees (mdeg) for the 64-m antennas, and 11 millidegrees for the 34-m antennas. Th

new Mark IVA antenna pointing system contained new computers and new equipmen

all of which required new calibrations and procedures for making the calibrations.

There were two ways of pointing the DSN antennas. In “blind pointing,” an antenn

pointing prediction program derived from the spacecraft ephemeris, the antenna com

puters are fed data for necessary corrections before sending pointing signals to the serv

to drive the antenna. This method did not rely on any downlink signal from the spac

craft, and was used during radio astronomy occultation observations and spacecra

acquisitions. In “conical scanning” (conscan) the antenna was moved in a conical sca

ning motion about the approximate direction of the spacecraft. Error signals, deriv

from a comparison of the downlink signal strength at opposite parts of the scan pa

tern, were used to drive the antenna to a “null” position. The “conscan” mode th

enabled the antenna to sense the apparent direction of the spacecraft radio signal. Th

method was useful in the absence of accurate predictions, or for searching for a “lo

spacecraft” signal.

During the pre-encounter period, a process for initial pointing calibration of the Ma

IVA antenna system was developed at the Madrid Deep Space Communications Compl

(MDSCC), using radio stars as distant target points of known position. After a seri

of radio star observations, the data were reduced to pointing angle offsets and used 

produce a systematic pointing error model. These data then provided the correctio

needed by the antenna predicts program for “blind pointing.” Typical accuracies obtain

from these observations were less than 4 mdeg for the 64-m antennas and less than 

mdeg for the 34-m antennas.

However, radio stars near the 23-degree south declination of the Voyager 2 spacecraft we

not available. For that declination, “conscan” offset data from live Voyager tracking pass

were used. Comparison of the apparent direction of the spacecraft signal given by consca

with the direction given by the corrected predict program, was the conscan offset. To t

extent that the conscan properly sensed the apparent direction of the spacecraft signal, t

200

Uplink-Downlink: A History of the Deep Space Networ
conscan offsets determined the total system pointing errors. Using this method on a lar

number of tracks at Goldstone, it was determined that the conscan defined axis and t

actual antenna beam axis were coincident within 1 to 2 millidegrees. Subsequent tests 

Goldstone verified that the downlink signal level was not significantly affected by the metho

used to point the receiving antenna. With this basic information in hand, the CDSCC ca

ried out an extensive program of blind pointing exercises in preparation for support of t

radio science events connected with the Uranus encounter.

These investigations substantially improved DSN confidence in the ability of its ante

nas to support the outer planet missions without incurring significant downlin

degradation due to pointing errors, and laid to rest the initial concerns about antenn

pointing errors relative to the imminent Voyager Uranus Encounter.

The regular weekly Voyager project meetings provided a forum for discussion an

resolution of the issues and concerns described above. Based on these discussion

Voyager and DSN representatives gradually developed a mutually acceptable plan f

DSN support of what was by then called the Voyager Uranus Interstellar Mission.

Marvin R. Traxler continued to represent the DSN in these negotiations, while th

project was represented by George P. Textor, the newly appointed Mission Direct

for the Voyager project.

The DSN plan for Uranus met the project requirements for downlink telemetry at 

maximum data rate of 29.9 kilobits per second, improved the quality of radiometr

data for spacecraft navigation purposes, and further improved and expanded the rad

science data gathering capability of the Network. Antenna arraying techniques, based o

past experience with the Jupiter and Saturn encounters, and including the new, 34-met

high efficiency antennas and the Parkes radio astronomy antenna in Australia, were us

to enhance the downlink signal power received by the DSN stations, while the Ma

IVA-1985 model of the Network provided the new capabilities required to provide telem

try, command, radiometric, and radio science services for Voyager 2 at the Uranus encount

Both of these initiatives represented major increments in Network capability and we

subsequently used to great advantage not only by Voyager 1 and 2, but by all of th

other ongoing missions. The engineering and implementation particulars of these co

current streams of activity and the sensitive task of bringing them into service to me

the Voyager need date (mid-1985), without disruption to the routine operational su

port of the ongoing missions, are discussed later this chapter.

20

The Voyager Era: 1977–1986
Uranus Encounter

On 4 November 1986, 81 days before Voyager 2 was due to flash by the outer plan

Uranus, the Voyager flight team began continuous, extended observations of the Urania

system at better resolution than possible from Earth. The one-ton spacecraft was the

travelling at nearly 15 km per second (relative to Uranus), and radio signals travellin

at the speed of light were taking 2 hours and 25 minutes to reach the DSN antenn

on Earth, 2.88 billion km away. Uranus lay 103 million km ahead. This was the sta

of the observatory phase during which the spacecraft and DSN would be fine-tuned 

prepare for the close encounter observations. A pictorial diagram of the Voyager 2 m

sion including all its planetary encounters is given in Figure 4-10.

Two weeks earlier, the Voyager Flight Team had conducted a Near Encounter Test (NET

to validate the readiness of all elements of the project, including the DSN Flight Tea

and Science Team, to commence the Uranus Encounter operations depicted in Figu

202

Uplink-Downlink: A History of the Deep Space Networ

Figure 4-10. Pictorial diagram of Voyager 2 mission.
4-22. DSN participation in the NET demonstrated that while the DSN had the bas

capability to support the Near- Encounter phase, additional operational proficiency wou

be needed to reach the level deemed appropriate for those critical operations. This w

in large part attributable to the schedule slips that had occurred in the Mark IVA impl

mentation project. Hampered by budget changes and software problems, completion 

the implementation tasks had consumed the time that was originally planned for ope

ational training and proficiency activity.

On 5 November 1986, the DSN reviewed its status and responded to the deficie

cies that had shown up in the NET. Arraying, radio science, and operator trainin

were the principal areas of concern. The review found that, with the help of specia

ist engineering personnel supplementing the station operations crews during critic

periods, the DSN was ready to support the observatory phase. Further, the observ

tory phase would provide sufficient additional operational experience to enable th

stations to deal with the Far- and Near-Encounter phases. With this proviso and se

eral hardware and software liens against various elements of the new Mark IVA system

the DSN prepared to meet what was possibly its greatest challenge yet, the Voyager 

encounter of Uranus.

The spacecraft made its closest approach to the planet on 24 January 1986. Despi

the earlier anxiety about its scan platform, onboard computers, and one remainin

active radio receiver, the Voyager spacecraft performed perfectly. A final trajectory co

rection maneuver scheduled for 19 January was canceled since the flight path w

deemed satisfactory without further refinement. After travelling an arc of nearly 5 b

lion km to Uranus, the Navigation Team estimated that the spacecraft passed with

20 km of the aim point. This astonishing navigational accuracy had been achieved b

the use of spacecraft optical navigation to complement the Doppler, ranging and Del

differential one-way ranging (DDOR) data types provided by the DSN. Navigatio

accuracy is critical to the success of crucial science observations that depend not on

on knowledge of the spacecraft position but also on proper, accurate pointing of th

instruments aboard the steerable scan platform. The spacecraft executed these com

plex sequences without incident. The science data return quickly grew to avalanch

proportions as each of the science instruments carried out its preprogrammed obse

vations. Previously unknown facts about the planet, its atmosphere, rings, magnetospher

winds, and satellites were soon being presented to the “happily bewildered” scientis

Typical of the many beautiful imaging science results is the striking picture of Mirand

one of the inner moons of Uranus, shown in Figure 4-11.

20

The Voyager Era: 1977–1986
At a distance from Earth of two billion km (1.212 billion mi) and traveling at 65,00

km (40,000 mi) per hour, Voyager 2 passed within 31,000 km (19,000 mi) of Mirand

surface. Image motion compensation prevented smearing of the image during the lon

exposure times necessitated by the low lighting conditions at Uranus. The clarity of th

image amply demonstrates the capability of the Voyager imaging system combined wi

the benefits of image motion compensation and the excellent performance of the DS

downlink communications channel.

The new Mark IVA systems all worked well throughout the encounter period. At 

sites, array performance, including the Parkes element at Canberra, was close to pr

dicted values. The complex and lengthy radio science sequences at CDSCC were execut

without significant loss of data. The new Mark IVA Monitor and Control System cr

ated some difficulty at first, while the operations crews adjusted to the concepts 

centralized control in a critical operational environment.

204

Uplink-Downlink: A History of the Deep Space Networ

Figure 4-11. Voyager 2 image of the Uranus satellite Miranda.
For the DSN, the Voyager Uranus Encounter in January 1986 had been a challenge 

deep space communications and operations complexity. To meet the Voyager requir

ments for science data return, the DSN had designed, implemented, and put into operatio

a complex system of arraying all the DSN antennas at each longitude. At Canberra, th

array had been supplemented with a non-DSN 64-m antenna, 280-km distance, belon

ing to a foreign agency. On the project side, a risky but successful inflight reprogrammin

of onboard computers had increased the efficiency of the telemetry data stream to com

plement the DSN improvements in the downlink performance. Special uplink tunin

sequences were required to compensate for the Voyager spacecraft receiver problem.

At the same time, the DSN had completed a Network-wide upgrade of the entire da

system to increase its overall capabilities and decrease operations costs by introducin

centralized control to station operations.

Together, the new technology, new methodology and limited time, created a difficu

position for the DSN in the weeks prior to encounter. Responding to this situatio

DSN operations and engineering personnel in Pasadena, Goldstone, Canberra, and Madr

were able to meet the challenge and the science returned from the Voyager Uran

Encounter attests to their success.

In the Voyager Uranus Encounter, three major advances in DSN capability, represen

ed by the Mark IVA Data System, antenna arraying, and centralized operations contro

had been successfully demonstrated under the most critical operational conditions. The

capabilities would carry the DSN forward into the Galileo Era, where once again th

Voyager mission would stretch the DSN downlink capability to its limits—the ne

time at Neptune.

20

The Voyager Era: 1977–1986
EXTENDED MISSIONS

Helios

The two Helios spacecraft successfully completed their prime missions in mid-1976 an

with both spacecraft in good operating condition, continued to orbit the Sun and retu

prime scientific data during repeated perihelion and superior conjunction periods f

many years. The DSN continued to support Helios as an extended mission by provi

ing tracking support as resources became available, mainly on the 26-m Network. Th

support was supplemented by the German tracking station, DSS 68 at Weilheim. Und

these conditions, the supportable downlink data rate was 64 bps.

In March 1980, the downlink transmitter on the Helios 2 spacecraft failed, and despi

numerous attempts by the DSN to restore communications with the spacecraft, no us

ful data could be recovered. On 8 January 1981, a command was sent to turn the Heli

2 spacecraft transmitter off to prevent it from becoming an uncontrolled source of rad

interference.

Helios 1, however, continued to operate normally and, supported primarily by a ne

work consisting of the two DSN 26-m stations, DSS 11 (Goldstone) and DSS 4

(Honeysuckle), and the German station DSS 68 (Weilheim), it participated in impo

tant collaborative experiments with Voyager, Pioneer, and ISEE-3 to study scientif

phenomena in the inner solar system.

When time became available on the 64-m subnetwork in December 1981, Helios 1 w

able to obtain continuous 64-m coverage for a six-day period coincident with the sol

conjunction period following the fourteenth perihelion passage. During this time, th

DSN radio science equipment was used to make measurements of Faraday rotation fro

a Sun-Earth-Probe (SEP) angle of 4.1 degrees on entry, to an SEP on exit of 3.8 degree

To carry out this type of experiment, the 64-m stations had been equipped with rota

able, microwave, linearly polarized feeds and closed loop polarimeters to automatical

and precisely measure the orientation of the linearly polarized downlink sign

Measurement of the Faraday rotation caused by passage of a radio signal through th

solar corona provides important scientific information about electron density and th

solar magnetic field.

Helios 1 continued to perform functions of this kind for several more years into th

Voyager Era, supported mainly by the 34-m antennas at low data rates (8–256 bps). A

the power from the solar generators weakened, the spacecraft could be operated only f

206

Uplink-Downlink: A History of the Deep Space Networ
a few months in each orbit. Eventually, both spacecraft receivers ceased to operate, an

without an uplink command capability to send correcting signals, the high-gain ante

na gradually drifted off Earth “point.” The downlink from Helios 1 was last seen at DS

43 Canberra on 10 February 1986, nearly 12 years after its launch in 1974. It was pr

dicted that, with diminished power available, the spacecraft would automatically sh

down its transmitters soon after.27

Viking at Mars

In June 1978, NASA gave approval to continue the Viking Extended Mission for a fu

ther Martian year (1.88 Earth years). This period of the Viking mission was called th

Viking Continuation Mission (VCM). Its purpose was to replace Orbiter imaging da

that had been lost or degraded during Sun occultation periods, to gather radio scien

data including near simultaneous Lander Orbiter ranging measurements, and to co

tinue to make occultation and gravity fields observations. Both of the Viking Lande

were placed in an automatic mode of operation to reduce the work load needed to ma

age Lander operations.

At the beginning of the VCM, management of the Viking project was transferred fro

the Langley Research Center to the Jet Propulsion Laboratory. The original flight tea

was reduced from about 800 personnel to 150, and DSN support for Viking missio

operations was cut from 168 to 40 hours per week. The operational workload was fu

ther reduced by placing both Landers in an automatic mode of operation to elimina

the need for daily attention by ground controllers. These economies in resources allow

DSN personnel to redirect their efforts to support the more critical mission phases 

the Voyager and Pioneer Venus flight projects.

The depletion of expendable attitude control gas had started to take its toll on th

Viking Orbiters. Although Viking Orbiter 1 (VO-1) was still performing normally, Vikin

Orbiter 2 (VO-2) continued to be plagued by intermittent gas leaks in the yaw-axis co

trol jets. On 25 July 1978, the transmitter on VO-2 ceased operating and the spacecra

was presumed to have finally lost attitude control capability. By the end of the ye

both of the S-band transmitters on VL-2 had also failed, leaving the Lander depende

on the relay link via VO-1 for returning its data to Earth. Nevertheless, both Lande

continued to collect meteorology and imaging data from the Mars surface and return 

to Earth either directly or via the relay through VO-1. Throughout the year, VO

remained in good condition and returned excellent radio science, imaging, and gener

relativity data.

20

The Voyager Era: 1977–1986
DSN support for the two Landers and the one remaining Viking Orbiter was curtail

even further in 1979 to make resources available for the Voyager Jupiter encounte

VO-1 was placed in a housekeeping mode in March and transmitted only spacecra

engineering data. The science systems were deactivated and new operating and prote

tion instructions were stored on the spacecraft to make it as self-sufficient as possib

Daily contact was not required, but the spacecraft was interrogated every two weeks 

check on its status.

In late 1979, VL-1 became a separate mission called the Viking Lander Monitor Missio

operated autonomously by command sequences stored in the Lander onboard compu

er. At the same time, VO-1 was designated as the Orbiter Completion Mission an

DSN support for it was increased.

Resuming its normal operating mode, VO-1 began returning high-resolution phot

graphic coverage of areas of the Martian surface that had not previously been obtain

or adequately covered in the earlier phases of the Viking mission. Included in this co

erage were possible landing sites for future Landers. (The Mars Pathfinder mission 

1997 used these images.) Frequent occultation events provided opportunities for rad

science observations of Mars atmospheric fluctuations, correlation of ionospheric plasm

temperature with solar activity, and improved knowledge of Mars topographic featur

and gravity anomalies. Both VL-1 and VL-2 remained in the automatic mode, pe

forming repetitive observations on 37-day cycles. VL-1 ranging data obtained direct

from the surface of Mars was collected to aid in improving the existing models of th

ephemeris of the planet. Meteorological data and imaging data were also returned pe

odically, as well as data from the inorganic analysis of the final sample of Mars soil.

In July 1980, the Office of Public Information at JPL issued the following press releas

“After more than four years exploring Mars, NASA’s Viking Orbiter 1 has almost reach

the end of its mission. The Orbiter has used most of its attitude-control gas, which kee

its solar panels pointed to the Sun and the antenna aimed at Earth. When the gas w

exhausted, about 23 July, controllers at JPL sent commands to turn off Viking Orbiter 

to end its long and productive mission.

“Meanwhile, Viking Lander-1 is programmed to operate unattended on Mars into 199

perhaps even into 1994 . . . . As long as it survives, Viking Lander-1 will continue 

collect photos and weather data from Mars and, on command from Earth, transm

them on approximately a weekly basis.”

208

Uplink-Downlink: A History of the Deep Space Networ
And so it was that at 20:15 GMT on 7 August 1980, a command from DSS 61 

Spain turned off the S-band and X-band transmitters on VO-1. This would preve

them from becoming an uncontrolled source of radio interference. Viking Orbiter 

would continue to silently orbit Mars for many decades until its decaying orbit wou

lead it to destruction in the upper reaches of the Mars atmosphere.

The Viking Orbiter Project Scientist compiled the following statistics of general inte

est for the Viking Orbiter missions.

Viking Orbiter Statistics of General Interest

Item VO-1 VO-2

Days from launch to end of mission 1,814 1,050

Orbits of Mars 1,488 706

Pictures recorded in orbit 36,622 16,041

Data bits played back from the tape recorders 358x109 161x109

Distance of tape travel across recorder heads (km) 2,955 1,397

Total number of commands sent by DSN 269,500

Tracking passes provided by DSN 7,380

Hours of tracking time provided by DSN 56,500

The Viking Orbiter 1 mission to Mars ended after five years of continuous DSN ope

ational support. The demise of the last Orbiter also deprived Viking Lander 2 of 

Earth relay capability and its mission, too, was ended.

The last of the Vikings, Lander 1, which was located in Chryse Planetia, had been ope

ating in an automatic mode since March 1979 transmitting stored engineering, imagin

and meteorological data on command from one of the DSSs. During the first exten

ed mission, one of the two spacecraft radio receivers failed, leaving the other receiv

permanently connected to the Lander high-gain antenna. Since that time, the Land

had been operating quite successfully but was completely dependent for its uplink an

downlink communications on a long-term antenna pointing program, previously stor

on the spacecraft, and was valid through 1994.

Managed and controlled by fewer than thirty people at JPL, this was to be the Vikin

Monitor Mission and hopes were high for a low-cost, long-lived science observation po

on Mars. Radio science, meteorology, and comparative time-lapse imaging were to 

20

The Voyager Era: 1977–1986
the principal mission objectives. These goals were achieved, over the next two yea

using whatever time became available in the busy DSN tracking schedules.

Despite the steady flow of good science data in 1982, all was not well with Lander 

Early in the year, three of the four nickel-cadmium storage batteries showed signs 

losing their energy storage capacity. For several months, the normal recharging sequenc

failed. Finally, in an attempt to extend the life of the batteries, advice was sought fro

experts in this field all over the country. These reviews led to recommendations for 

new battery charging strategy which would be incorporated into new Lander sequenc

and uplinked to the Lander on 19 November 1982 from DSS 43.

After the uplink was transmitted to the Lander, the station searched for the expect

downlink, but could find no sign of an S-band carrier signal. Shortly thereafter, th

spacecraft controllers realized with horror that the new battery-charging sequence h

been inadvertently written to the memory locations occupied by the Lander high-ga

antenna pointing program.

It followed that the high-gain antenna was no longer pointing to Earth and that un

the situation could be corrected by giving the high-gain antenna the correct Earth poin

ing instructions, communication with the spacecraft was no longer possible. In the mont

that followed, strenuous efforts were made to get commands into Lander 1 to retrie

control of the high-gain antenna but to no avail. Telecommunications link analyses show

that with the 100-kW DSN transmitters sending commands there was sufficient sign

strength at the Lander to reach the receiver even through a side lobe of the high-ga

antenna. Other failure modes were proposed, tried, and failed to produce a downlink

Finally the Mission Director decided that no further effort was warranted and, in Mar

1983, the Viking Lander Monitor Mission was terminated.

During the course of the Viking mission, a substantial contribution to the field of rad

science was made by investigators using the Orbiters, or Landers, or both. Based o

these results, scientific papers were published in the areas of general theory of relativi

solar-wind scintillation, dynamics shape and gravity of Mars, gravity waves, solar grav

ty, solar-wind electron density, and improvement in the Mars ephemeris.

Observations from the VL-1 meteorology sensors provided major insight into many Ma

atmospheric processes such as frontal systems, annual climate variations, and dust storm

210

Uplink-Downlink: A History of the Deep Space Networ
The VL-1 cameras were programmed to view each Martian scene periodically with th

same camera parameters, including pointing. In this way, comparative imaging could 

used to observe for dust, condensation, or erosion over a period of time. Until the m

sion was terminated, several imaging frames showing these processes were obtained.

The Viking Lander 1 was eventually renamed the “Thomas A. Mutch Memorial Station

Dr. Thomas A. Mutch was the Viking Project Scientist who disappeared while on 

climbing trip in the Himalayas in 1980.

The world press noted the passing of the last Lander with many tributes and accolade

For nearly twenty years, the Viking presence on Mars had provided a topic for a co

tinuous stream of articles and reports of fact and speculation. In May 1983, the Ne

York City Tribune published an article by international science writer J. Antonio Huneeu

which recognized the Viking endeavor quite succinctly: “Together the two Landers too

more than 4,000 photos of the Martian surface, while the Orbiters took over 50,00

photos. They mapped 97 percent of the Mars’ surface with a resolution of 25 mete

More than three million Martian weather reports were received between the two Lande

and a number of other experiments were conducted.

“However, what received most publicity at the time were the experiments designed 

search for ‘evidence of living organisms and organic molecules on the Martian surfac

Again, it was the first, and so far only, time that such an experiment had been co

ducted on another planet. Although some scientists had high hopes that the experime

would reveal important principles about extraterrestrial life processes, the results we

inconclusive.

“In NASA’s own words, ‘no clear, unambiguous evidence of life was detected in the so

near the landing sites.’ But the space agency adds that, ‘the question of life on Ma

according to Viking biologists, remains an open one.’ ”

And that is where it remained for the next twenty years until the new Mars initiati

opened in 1997, with the spectacular appearance of Mars Pathfinder on the world’s spa

scene. It, too, was renamed to memorialize one of its strongest advocates. The new st

tion became the “Carl Sagan Memorial Station.”28

Pioneers 6, 7, 8, 9

The Pioneer 6, 7, and 8 spacecraft remained in an orbit around the Sun similar to th

of Earth, varying between 0.8 and 1.2 AU. All three spacecraft remained in good ope

21

The Voyager Era: 1977–1986
ating condition as they continued to be supported as extended missions, through th

Voyager Era. They provided field and particle data individually and in conjunction wi

other solar wind measuring spacecraft when conditions of alignment were favorable.

The last successful DSN acquisition of Pioneer 9 took place on 18 May 1983. Un

that time, the spacecraft had been tracked periodically as schedules permitted, but o

the last scheduled track in October, a downlink could not be detected. Over a span 

several years, commands were sent to configure the spacecraft into all possible comb

nations of receivers, decoders, transmitters, and antennas in an effort to reestablish th

downlink. The SETI multispectral analyzer at Stanford was used to try to detect a we

signal, but with no success. In all, eighteen separate attempts were made to revive th

spacecraft to no avail. The Pioneer Project Office declared the end of the Pioneer 9 m

sion on 5 March 1987.

Pioneers 10, 11

The Pioneer 10 spacecraft, launched in March 1972, reached Jupiter in December 197

and continued on a path 2.9 degrees above the ecliptic that would eventually take 

out of the solar system. Throughout the Voyager Era, it continued to maintain an uplin

and a downlink with the DSN while returning a continuous stream of particle and fie

science data, and participating in several collaborative experiments with other spacecra

in different parts of the solar system.

The Pioneer 11 spacecraft was launched in April 1973 and reached Jupiter in Decemb

1974. Using the strong gravitational field of Jupiter to redirect its trajectory, Pioneer 1

reached Saturn in September 1979. Throughout the long cruise time between Jupit

and Saturn, the spacecraft remained in excellent condition with few system problem

During this period, the DSN provided routine tracking and data acquisition suppo

while the mission was controlled from the Pioneer Mission Operations Control Cent

at Ames Research Center (ARC) in Mountain View, California. The heliocentric geom

etry of the Pioneer 10 and Pioneer 11 trajectories are shown in Figure 4-12.

After its Saturn Encounter, Pioneer 11 escaped the solar system travelling a directio

opposite that of Pioneer 10, which was already on a solar escape trajectory. It was expec

ed that Pioneer 11 could be tracked by the DSN through 1987.

The DSN prepared to support the Pioneer 11 Saturn Encounter with new S-band mase

in all three 64-m stations. Additional downlink performance would be obtained for 

few days, during the closest approach, by operating the 64-m stations in the receiv

212

Uplink-Downlink: A History of the Deep Space Networ
only mode to gain an extra 0.7 dB. Because of the extensive uplink command activi

required, the uplink would be provided by the 26-m stations consisting of DSS 44 an

DSS 62 and the recently completed 34-m antenna at DSS 12.

To further enhance the downlink capability during the 14-day encounter period, an expe

imental arraying technique would be used at Goldstone to combine the signals from th

34-m antenna at DSS 12 with those from the 64-m antenna at DSS 14 in a real-tim

combiner. An improvement in signal to noise ratio of 0.4 dB to 0.5 dB was predict

at antenna elevations above 13 degrees. This would be verified by demonstration trac

using live spacecraft data at 1,024 b/s (coded) over DSS 12 and DSS 14 prior to encount

Because the closest approach distance would be less than two Saturn radii from the ce

ter of the planet, the rate of change of the S-band Doppler frequency at encounter wou

reach as high as 70 Hz per second. This would be too great for the DSN receivers 

track unaided. This fact, coupled with the low downlink signal level resulting from th

21

The Voyager Era: 1977–1986

Figure 4-12. Pioneer 10 and 11 heliocentric trajectories, September 1979.

URANUS

SATURN JUPITER

SUN

EARTH

1

1

P - 10 OUTBOUND

ASYMPTOTE 2.9 deg

ABOVE ECLIPTIC

P - 11 OUTBOUND

ASYMPTOTE 12.6 deg

ABOVE ECLIPTIC

1. P - 10 JUPITER ENCOUNTER DECEMBER 4, 1973 2. P - 11 JUPITER ENCOUNTER DECEMBER 3, 1974 3. P - 11 SATURN ENCOUNTER SEPTEMBER 1, 1979

2

3
extreme Saturn range, necessitated the use of preprogrammed receiver tuning at the st

tions that would observe the closest approach event of the encounter. The receivers at DS

12, DSS 14, and DSS 63 would be automatically tuned to ramp out the rapid change 

Doppler as the spacecraft swung by the planet. In the absence of an automatic tunin

capability, relays of operators were employed to manually tune the receivers at DSS 6

To assist the spacecraft receiver in tracking the uplink frequency changes, similar arrang

ments at DSS 12 and DSS 62 would control the DSN transmitter exciter frequency.

During the seven-day period on either side of closest approach, the DSN efforts to su

tain a 1,024 bps data rate to support the imaging polarimeter met with various degre

of success. On occasions, problems with the Goldstone array, with telemetry decod

performance, Canberra weather, and some radio interference from a Russian satelli

forced the project to reduce the data rate to 512 bps. The net result was a return 

approximately twenty pictures better than Earth-based resolution instead of the for

pictures that would have been possible had the 1,024 bps data rate been sustained f

the entire period. Even so, the science data return was still very extensive, leading th

Pioneer Imaging Team to estimate that the scientific data return from the Pioneer 1

Saturn Encounter exceeded that from both the Pioneer 10 and Pioneer 11 encounte

of Jupiter.

In addition to imaging and field and particle science, several radio science experimen

were carried out during the encounter period. The ring plane crossing on 1 Septemb

the Saturn occultation shortly afterwards, and superior conjunction beginning on 1

September afforded opportunities for radio science observations.

Following its Saturn encounter on 1 September 1979, Pioneer 11, too, began to mo

along an endless path above and out of the ecliptic in the opposite direction to Pione

10 and at a considerably steeper angle. All systems aboard the spacecraft were perform

ing normally. Like Pioneer 10, it would remain a fully operating spacecraft, collectin

fields and particle data and participating in collaborative experiments, as its signal slow

ly weakened with increasing range.

Managed from the ARC Mission Control Center in Sunnyvale, California, both spac

craft would remain a presence on the DSN tracking support schedules throughout th

entire Voyager Era.

Performance estimates, based on measured performance in 1980, indicated that the 6

m stations using the 18.5-kelvin low-noise S-band receivers would be able to suppo

the Pioneer 10 spacecraft at a data rate of 16 bps through 1989, 4 years and 13 A

214

Uplink-Downlink: A History of the Deep Space Networ
greater than previous estimates. By 1990, the distance from Earth would be 7 billio

km, the DSN radio transmissions would be taking over 13 hours to travel to Pione

10 and back, and the signal level received at the 64-m DSN antennas would be 17

dB below 1 milliwatt (-172 dBm). At the same time, the Pioneer 11 distance would 

4.5 billion km and its data rate would be 32 bps. The life of both spacecraft wou

ultimately be determined by the life expectancy of their Radioisotope Thermoelectr

Generator (RTGs) power sources, rather than the downlink telecommunication lim

of the DSN antennas.30

Pioneer 12 (Venus Orbiter)

Pioneer 12, the orbiting spacecraft of the two Pioneer Venus missions of 1978 (the oth

was a Venus atmospheric entry multiprobe) continued to operate normally through th

Voyager Era, collecting a wealth of new information about Venus. In 1980, the fir

detailed radar maps of Venus were compiled using data returned from Pioneer 12. A

the shape of its 24-hour orbit gradually changed, Pioneer 12 observed the bow sho

and the ionospheric tail of Venus in 1983 and 1985. Making use of its ultraviolet spe

trometer, Pioneer 12 observed Comets Encke in 1984, Giacobini-Zinner in 1985, an

Halley in 1987, as well as several other comets.

Although the spacecraft used an S-band uplink and downlink for regular communic

tions with the DSN, it also carried a 750-milliwatt, X-band transmitter intended specifical

for carrying out radio science experiments during occultation periods. The DSN su

ported numerous radio science experiments with Pioneer 12 using this capability. Celest

mechanics experiments determined irregularities in the Venus gravitational field and du

frequency (S- and X-band) occultation experiments provided new data about the Ven

atmosphere.

Still active in its prime mission phase, Pioneer 12 was supported regularly on the 64-

network through the entire Voyager Era.

21

The Voyager Era: 1977–1986
HIGHLY-ELLIPTICAL EARTH ORBITERS

International Cometary Explorer (ICE)

The ICE spacecraft started life as the International Sun Earth Explorer (ISEE) and spe

the first five years of its life in heliocentric orbit observing solar wind effects in th

region between Earth and the Sun. During this period, tracking support was provid

by the 26-m stations of the Ground Spaceflight Tracking and Data Network (GSTDN

In 1983, ISEE-3 was retargeted to intercept Comet Giacobini-Zinner on 11 Septemb

1985, and renamed the International Cometary Explorer (ICE). The Spacecraft to Ear

distance at comet encounter would be 0.47 AU. On its new trajectory, ICE soon excee

ed the tracking capability of the 26-m antennas and, in January 1984, became the fir

of the highly elliptical Earth-orbiting satellites to depend on DSN 64-m antennas f

tracking and data acquisition support.

Designed for use in a near-Earth orbit of about 0.01 AU, the ISEE-3 downlink wou

be reduced in strength by a factor of 2,500 when the spacecraft, as ICE, encounter

the comet. Not only would the DSN 64-m antennas be required, but significant, inn

vative enhancements to the existing DSN receiving and telemetry data processing capabiliti

would also be necessary to support a telemetry data rate of 1,024 bps from ICE 

comet encounter.

The ICE spacecraft carried two identical, S-band, 5-watt transmitters that could be us

interchangeably to carry telemetry or ranging data. One transmitter operated at 2,27

MHz, the other at 2,217 MHz. To overcome the problem of downlink signal margi

the DSN proposed to transmit telemetry on both downlinks simultaneously and to com

bine the separate signals at the DSSs before feeding the combined signal to th

demodulation, synchronizing, and decoding processors. In addition to the two dow

links from a single 64-m station, single downlinks from nearby 34-m stations could 

added to the combiner, to further enhance the downlink prior to data processing.

Earlier studies had evaluated the feasibility of this approach and estimated that, und

optimum conditions, this arrangement could provide an improvement of 3 to 4 d

compared to the use of a single 64-m antenna and a single downlink.

Implementation of the scheme, however, proved to be very difficult. Simultaneous rece

tion of the two downlink carriers on a single 64-m antenna required the addition 

new wide-bandwidth masers, which initially experienced problems with gain and ban

216

Uplink-Downlink: A History of the Deep Space Networ
width stability. Special multiport resistive combiners were built and installed at each 

the DSCCs.

Several hundred hours of link performance on the ICE data were accumulated and eva

uated in mid-1985 as the encounter time approached. The marginal signal power availab

from the spacecraft at this range made it essential to account for every 0.1 dB of telem

try performance that could be extracted from the combined downlinks.

The large radio astronomy antenna at Arecibo, Puerto Rico, was also scheduled to su

port the ICE for a short time during the crossing of the comet tail. For this purpos

new receiving and telemetry equipment for the 2,270 Mhz downlink was provided b

GSTDN.

Additional support near the Australian longitude was to be provided by the Japane

64-m antenna at Usuda, Japan. Under a joint NASA-ISAS agreement, the station wou

be implemented with the necessary low-noise maser amplifier and telemetry processin

equipment by the DSN. The high aperture efficiency of the Usuda antenna, togeth

with the low-noise maser configuration, resulted in a downlink performance almost equi

alent to the DSN 64-m dual channel configuration.32 A block diagram of the DS

configuration for support of the ICE encounter with comet Giacobini-Zinner is show

in Figure 4-13.

Configuration testing, resolution of problems, and intensive crew training continued 

all sites right up to the actual encounter time. ICE passed through the tail of Com

Giacobini-Zinner on 11 September 1985. The three sites having view of the even

Madrid, Goldstone, and Arecibo, successfully acquired the spacecraft and reported goo

downlink performance at or above the predicted level. Telemetry data was sent via hig

speed data line to the ICE Principal Investigators at GSFC from all three sit

simultaneously. The Madrid Complex sent arrayed data from the 64-m antenna and on

34-m antenna, while the Goldstone Complex sent data from its 64-m antenna and tw

34-m antennas. The Arecibo site sent data from one downlink during the overlap 

the Madrid and Goldstone view periods. The multiple data streams allowed the missio

controllers at GSFC to choose the best data stream for delivery to the investigators f

scientific analysis.

The return of telemetry data at 1,024 bps, from this historic first encounter with 

comet, was made possible to a large degree by the application of DSN analysis, eng

neering, and operations expertise to refinement of the ICE downlink.

21

The Voyager Era: 1977–1986
218

Uplink-Downlink: A History of the Deep Space Networ

Figure 4-13. DSN configuration for ICE encounter of Comet Giacobini-Zinner, 11 September 1985. 2-PORT COMBINER 3-PORT COMBINER 4-PORT COMBINER 3-PORT COMBINER 2-PORT COMBINER

DSS 63 DSS 61 DSS 15 DSS 12 DSS 14

STRING

1

STRING

2

STRING

3

STRING

2

STRING

1 ODR

ODR

ODR

ODR ODR

ODR

56K 9.6K

ARECIBO,PUERTO RICO

56K

ARA

ODR 56K

ARA

PRIME B/U

TLMSTRING

ODR

ODR ODR

ODR

STRING

1

PRIME

ODR

STRING

3 ODR

STRING

2

B/U

ODR ODR

56K

NOCC ECS

CDSCC GDSCC MDSCC

DSS 42 DSS 43

ARA

DRG

STRING

2

STRING

1

GSFCMSOCCAND TIPIT USUDA, JAPAN
For the rest of the Voyager Era, the DSN would track ICE as schedules permitted wh

it continued to return science data, generally at a lower data rate, as it pursued its hig

ly elliptical Earth orbit around the Sun.31

Active Magnetospheric Particle Tracer Explorer (AMPTE)

The AMPTE spacecraft consisted of three separate satellites: Charge Composition Explor

(CCE) provided by the U.S., Ion Release Module (IRM) provided by the Federal Repub

of Germany, and the United Kingdom Satellite (UKS) provided by the U.K. From hig

ly elliptical Earth orbits, the three satellites would engage in an international, cooperati

study of the interaction of the solar wind with Earth’s magnetosphere. The prime m

sions would last about one year for the IRM/UKS, and four years for the CCE. Proje

management was exercised by Goddard Space Flight Center (GSFC), for NASA, 

cooperation with DFVLR.

Following launch from Cape Kennedy by a single Delta 3924 launch vehicle in Augu

1984, all three satellites were placed in highly elliptical Earth orbits by onboard propu

sion units. The final orbit for CCE was 1,148 km by 7.78 Earth radii (Er), while th

of the IRM and UKS was 407 km by 17.7 Er.

All S-band uplinks and downlinks for telemetry, command, and ranging communic

tions provided by the spacecraft were compatible with the capabilities of both ESA an

DSN ground tracking stations.

The AMPTE would be the first Highly-elliptical Earth Orbiters (HEO) to be suppor

ed by the DSN following completion of the Network consolidation project. Beginnin

in August 1984, the three 26-m antennas recently transferred from GSFC (DSSs 1

46, 66), would supplement the DSN 34-m standard antennas to provide coverage f

the CCE. The 34-m standard antennas would support all three spacecraft. The thr

64-m antennas would be required to support critical downlinks only. The ESA trackin

stations provided additional support for the IRM/UKS satellites.

Following a critical period from August 1984 through April 1985, when daily 8-ho

passes were required, tracking coverage was reduced to two-hour tracks, twice daily, f

CCE spacecraft tape recorder data dumps and radiometric data support.

Downlink telemetry data rates for the CCE varied from 3.3 kbps (real time) to 105

kbps (playback). Uplink command data rate was 125 bps. Radiometric data consist

of standard DSN ranging data only. Telemetry data was provided to the project at GSF

21

The Voyager Era: 1977–1986
in the form of digital Original Data Records (ODRs). Telemetry data from the 26-

stations were provided in the form of analog recordings.

The AMPTE missions introduced the DSN to the new HEO mission types which we

to become a very significant part of the total DSN effort in ensuing years. Althoug

the IRM/UKS satellites ceased to be of concern to the DSN in mid-1985, the CC

continued to require support as an extended mission through 1989.

220

Uplink-Downlink: A History of the Deep Space Networ
REIMBURSABLE MISSIONS

By 1984, the reputation, maturity, and unique capabilities of the Deep Space Networ

as well as the international value of the dollar, had made the DSN attractive to man

non-NASA and foreign space agencies as a viable alternative to their own facilities f

tracking and data acquisition support of Earth-orbiting missions. In this environmen

NASA had begun to explore the possibilities of providing DSN support for non-NAS

programs on a reimbursable basis, in addition to that which it already provided to no

NASA missions on a cooperative basis. Representatives of the NASA Office of Trackin

and Data Acquisition (OTDA), supported by the technical staff from the DSN, bega

to establish working relationships with several other national space centers and foreig

space agencies to explore the possible use of DSN resources for non-NASA, Earth-orb

ing missions, on a reimbursable basis.

As a result of these actions, requirements for support of non-NASA missions began 

appear, along with those for NASA missions, in the standard DSN documentation 

the period.33 Suddenly, the DSN was involved, not only with a new class of Eart

orbiting missions, known generically as “reimbursables,” but also with many new foreig

space agencies, some of which are listed below.

1. Europe: European Space Agency (ESA)

2. Italy: Agencia Spaciale Italiana (ASI)

3. Germany: Deutsche Forschungs-und Versuchsanstalt fuer Luft und Raumfahrt (DFVLR

4. Germany: Bundesministerium fuer Forschung und Technologie (BMFT)

5. Japan: National Space Development Agency (NASDA)

6. Japan: Institute of Space and Aeronautical Science (ISAS)

7. Spain: Instituto Nacional de Technica Aeroespacial (INTA)

8. France: Centre Nationale d’Etudes Speciale (CNES)

9. Russia: (Former Soviet Space Agency) Astro Space Center (ASC)

22

The Voyager Era: 1977–1986
Prior to the formalization of the reimbursable process in 1991, interactions betwee

those taking part in the interagency negotiations were rather informal. Joint technic

Working Group Meetings initiated by the DSN usually alternated between the vario

foreign agencies and JPL, and were used to plan support for upcoming missions, d

seminate information of mutual interest regarding DSN current status and future plan

and assess potential DSN support for future reimbursable missions. Science consider

tions for these missions were not a topic at these meetings. Where technical and operation

support by the DSN was the subject of discussion, Robert M. Hornstein, or anoth

associate, represented NASA Headquarters, while R. J. Amorose, or one of his ma

agers, spoke for the DSN.

It was the joint Working Group Meetings that afforded a medium for the definitio

discussion, and approval of the detailed technical and operational interfaces between th

DSN and the non-NASA user agency. Later, these interfaces would be published in th

appropriate interface control documents. Quite frequently these activities were takin

place while the formal approvals were still in progress. It, too, was an iterative proce

which, since NASA looked to the DSN for an estimate of the costs involved, neces

tated a thorough understanding of the prospective user’s requirements before the desir

support could be formally approved. These meetings were a necessary precursor to th

formal request to NASA for reimbursable support.

Generally, the DSN appointed a Tracking and Data Systems Manager (TDSM) to co

vene the meetings, represent it in the negotiations, and be responsible for all aspects 

DSN support once the mission began. The TDSM for the reimbursable missions, 

which there were several in progress at any one time, was also accountable for the DS

antenna time and other resources which were expended in support of the mission, an

for reconciling with the original estimates on which the support had been based.

In a directive issued in 1991,34 the Director of Ground Networks, Robert M. Hornstei

set out a “NASA policy covering the use and reimbursement of the NASA ground ne

works by non-NASA users.” This document applied to the Deep Space Network, 

addition to the two other NASA ground networks, the Spaceflight Tracking and Da

Network (STDN), and the Wallops Tracking and Data Facility. It identified the ava

able, standard services, which included tracking, radiometric data for orbit determinatio

acquisition of telemetry data, transmission of commands, radio science data recordin

prelaunch support planning, and documentation and delivery of the data to a NAS

Communications Network (NASCOM) gateway. Other special services, unique to pa

ticular missions, were also identified. It was, in short, a “full service” policy.

222

Uplink-Downlink: A History of the Deep Space Networ
Requests for service were to be provided “36 months before the requested service da

for NASA’s assessment and determination if the service could be provided.” Users we

required to “submit a letter of intent, together with an earnest money deposit to ini

ate planning activities leading to the provision of services.” Work could not begin un

a reimbursable arrangement describing, “the support to be provided, the schedule f

the support activities, the cost estimate, the progress schedule and any necessary term

and conditions for the support,” had been completed.

The costs for reimbursable services were based on “the number of actual support hours pr

vided by each antenna multiplied by an appropriate rate schedule,” which was revised b

NASA each fiscal year. To this were added miscellaneous costs for Headquarters and DS

technical staff, travel and administration, software modification, DSN navigation suppo

documentation, testing, and support from other elements of the ground network.

A NASA Management Instruction (NMI), issued in 1991, conveyed the essence of th

policy to all NASA Field Centers, including JPL. The NMI included specific conditio

and procedures by which non-NASA organizations could request DSN support. With

the DSN, these instructions were translated to the working level for the guidance of th

technical and administrative staff that would implement reimbursable mission operatio

in the Network.35

The costs and number of reimbursable missions in the DSN Mission Set varied co

siderably over the years following their first appearance in 1985. The hourly cost for 

26-m or 34-m antenna from 1985 through 1990 was $920 per hour. By 1992 this h

risen to $1,100 per hour. The hourly rate for the 64-m antennas was double those rate

In 1993, this rate, which was then adjusted annually to reflect the current operatin

costs of the Network rose to $2,825 per hour for the 26-m and 34-m antennas, an

$5,650 per hour for the 70-m antennas.

Reimbursable missions made their first appearance in the Network toward the end 

the Voyager Era, with four television broadcast satellites, TV-SAT (German), TDF

(French), and BS-2B and MS-T5 (Japanese). DSN support for each of them was of re

atively short duration (days to weeks) and involved only the 26-m and 34-m antenn

with existing capabilities. From this modest beginning in 1985, the number of “reim

bursables” in the total DSN mission set would steadily increase to become a major effo

as the DSN moved into the Galileo Era.

22

The Voyager Era: 1977–1986
NETWORK ENGINEERING AND IMPLEMENTATION

New 34-meter High-Efficiency Antennas

With the success of the DSN 26-m to 34-m antenna conversion program fresh 

mind, the earliest design for the NCP/MK IV program was predicated on upgra

ing the 26-m GSTDN antennas which had been moved to the DSN sites as part 

the Consolidation program, to 34-m. These antennas were, however, X-Y mou

design and not at all suitable for DSN, deep space tracking applications. Furth

reconsideration and cost versus performance studies led to a decision to build a s

of completely new antennas, based on a design study on larger antennas versus mu

tiple antenna arrays, which had been made for the DSN by Ford Aerospace in th

mid-1970s. The new antennas were to be built as 34-m array elements having receiv

only capability. There would be no transmitter and the common aperture feed wou

be optimized for X-band at the expense of S-band performance. DSS 15 and DS

45 were funded in FY 1981 to meet the immediate need of Voyager at Uranus, an

funding for DSS 65 was deferred until FY 1984. By that time, the future Magella

requirements for an X-band uplink were in part responsible for the completion 

DSS 65.36

The high-efficiency antennas, so-called because the aperture efficiency at X-band w

relatively high (approximately 70 percent), were intended to supplement the 34-

standard antennas and the 64-m antennas in an arrayed ensemble of antennas. Th

differed from the standard 34-m antennas mainly in having an azimuth-elevatio

(Az-El) wheel and track mount rather than an Hour-Angle-Declination (HA-DEC

mount. They had a single, common feedhorn for both S-band and X-band and n

transmitter. A Block II maser, transferred from the 64-m stations, provided for X

band reception and a cooled Field Effect Transistor (FET) was used for S-ban

reception.37

The antenna structure was designed to maximize stiffness, minimize distortion, and pr

vide accessibility for maintenance. It was mounted on a four wheel azimuth turntab

consisting of a square platform with self-aligning wheels, rotating on a circular, machin

track. The Az-El wheel and track mounting structure can be clearly seen in this pho

(Figure 4-14) of the first HEF antenna to be completed, DSS 15 at Goldstone.

The main reflector surface was shaped by the contiguous positioning of individual pa

els to present a homologous paraboloid for improved microwave efficiency. The quadripo

and apex structure was designed to limit aperture blockage to five percent. The al

224

Uplink-Downlink: A History of the Deep Space Networ
minum subreflector was constructed from six individual panels overlaid with aluminu

tape to form a continuous conducting surface. The subreflector three-axis positionin

mechanism served to minimize microwave performance loss due to gravity deformatio

of the antenna primary structure, quadripod, and primary reflector when the antenn

was operating at various elevation positions.

The antenna drive system was integrated with the Mark IVA configuration in th

SPC via interconnecting microprocessor computers. Antenna position control signa

trajectory prediction data, systematic error correction tables, transformation of coo

22

The Voyager Era: 1977–1986

Figure 4-14. 34-meter high-efficiency (HEF) antenna: DSS 15, Goldstone.
dinates, and monitor data were handled by drive and control equipment located o

the antenna, and by the pointing computers in the SPC. Microwave subsystem co

figuration control was also exercised from the SPC. No operators were required 

the antenna site.

When completed, the high-efficiency antenna cost about $4,800,000 (1986 U.S. do

lars) each.38

Typical microwave performance parameters are given below:

Parameters X-band (8,400 GHz) S-band (2,300 GHz)

Antenna Gain (dB) 68 56

System Noise Temp.

(kelvin) 20 40

The parameters given in the table above are intended for illustration only. Under ope

ational conditions these values changed significantly, depending on the microwa

configuration in use, the specific low-noise front-end amplifier, the antenna elevatio

weather, etc. These effects were important factors to be taken into account in designin

uplinks and downlinks, and were given, explicitly for that purpose, in the “Deep Spa

Network to Flight Project Interface Design Handbook.”39

The first HEF antenna at Goldstone, DSS 15, was brought into service with th

Mark IVA and SPC 10 in October 1984, followed by DSS 45 at SPC 40, Canberr

in December 1984. The HEF antenna at the Madrid Complex, DSS 65, becam

operational with SPC 60 in April 1987 with the additional capability of a 20 kW

X-band transmitter to support the Galileo and Magellan missions. The added X

band uplink transmit capability was retrofitted to DSS 45 and DSS 15 in 1987 an

1988.

The 64-meter to 70-meter Antenna Extension

Nowhere in the Deep Space Network was the ardent pursuit of refinement in the uplin

and downlink more apparent than in the 70-meter antennas. They were the single mo

obvious structure to draw and hold the attention of the thousands of people who v

ited the complexes in Australia, Spain, and California each year. Technical an

nontechnical visitors alike were fascinated by the huge, gleaming white structures th

readily conveyed the sense of deep space communications links with spacecraft in d

tant parts of the solar system. These were not fragile laboratory instruments continuous

226

Uplink-Downlink: A History of the Deep Space Networ
nurtured by white-suited laboratory technicians. These instruments were rugged eng

neering marvels that were designed to run continuously, exposed to all kinds 

environmental conditions, from the searing heat of a Mojave Desert summer, to th

driving winds and freezing rain of a Canberra winter, while maintaining a mechanic

and electrical performance equivalent to the most sophisticated of laboratory instrumen

Their size was deceiving. Seen alone against the natural contours of the surroundin

country, the size of the antennas did not appear to be their most striking feature. It w

the intricate complexity of the structure that impressed the viewer. But seen against 

human figure at the base or on the antenna, or a truck or building, the visitor was co

founded by the size of the structure. Taller than a 20-story building and over one ac

in surface area, the antenna itself was impressive even when stationary. When it was 

silent motion, slewing from the horizon position of a setting spacecraft to acquire th

downlink from another spacecraft, rising like a planet from the opposite horizon, th

sense of awe was complete.

Impressive though the external appearance of the 70-meter antenna was, the exquisi

design and engineering that allows it to function as a major element in the uplink an

downlink between Earth and the distant spacecraft could not be seen from outsid

Indeed most of it could not be seen at all, for it lay embedded in the technical deta

of the electrical and mechanical performance specifications that were associated with a

operational 70-m antenna of the Deep Space Network.40

It was no accident that this “jewel in the crown” of the DSN looked and perform

as well as it did, for it represented the culmination of a process of continuous deve

opment, refinement, and operational experience extending over twenty years since th

first 64-meter antenna became operational at Goldstone, in 1966. From that tim

until 1987, the network of three 64-m antennas served the DSN well in supportin

the mission sets of the Mariner, and Viking, and Voyager Eras described in this an

earlier chapters.

By 1982, however, interest in enhancing the capability of the 64-m antennas had reach

the point where the chief engineer of the Tracking and Data Acquisition Office, Robertso

Stevens, would recommend “that we embark on a program to design and impleme

the full technical performance potential of the 64-meter antennas.” He went on to gi

performance and cost predictions for several options.

For Robertson Stevens, JPL was his first, and only, employer. Hired straight after co

lege graduation (1949) with a master’s in electrical engineering from the University 

California at Berkeley, Robertson (Bob) Stevens remained with the DSN throughout h

22

The Voyager Era: 1977–1986
working life. With a family background associated with Naval aviation, Bob Steven

education path moved through San Diego, Sacramento, and the Naval Academy, gat

ering qualifications before reaching Berkeley.

Stevens’s career began with antennas and communications systems for the Corporal an

Sergeant missiles, during JPL’s Army period. By 1960, the start of the Ranger perio

Stevens had become head of the Communications Elements Research Section in Rechtin

Telecommunications Division. While Stevens concerned himself with developing the el

ments of communications systems; antennas and amplifiers, masers and microwave

transmitters and timing systems, Walt Victor’s Communications Systems Research Sectio

focussed on research at the protoype systems level. In due course, Stevens followed Vict

to become manager of the Telecommunications Division. Most of the significant advanc

in communications technology that eventually found their way into the operational Netwo

were made in that division, under his direction.

A great believer in physical fitness, Bob Stevens rode his bicycle five miles to and fro

JPL each day across the busy Pasadena city streets. On the job, he always seemed to 

around to encourage or help his engineers when the going was rough, sleepless li

everyone else during all-night tests at Goldstone, or calm and confident in the Netwo

Control Center at JPL, wearing his good-luck red vest during a launch or critical pla

etary encounter. Together with Mahlon Easterling, who introduced the DSN 

block-coding as an enhancement for the Surveyor downlink, this author and Bob Steve

appeared regularly with his flute or guitar to play carols at midday Christmas parti

around the “Lab” in the freewheeling days when that was permitted. Tousled dark ha

a ruddy complexion, a ready smile, and a hearty laugh were typical of the man. Steven

casual, slightly ruffled appearance and somewhat shy manner belied the intensity of th

attention that he brought to bear on matters that concerned him. He had a wonderf

ability to resolve issues between upper management, who often did not understand th

technicality of the issues before them, and engineers, who did not appreciate the co

straints those technicalities an issue. Later, as chief engineer for the Telecommunicatio

and Data Acquisition Office, he applied his many talents to the role of “troubleshoo

er” for the office.

He retired from JPL in 1991. As Stevens saw it, the “full potential of the 64-m ante

nas” would only be realized by the “Ultimate” option described by the performance an

cost parameters shown below. And that, he said, was his recommendation. It was a pow

erful statement, and on that basis the project went forward.

228

Uplink-Downlink: A History of the Deep Space Networ
Options for Upgrading the 64-Meter Antenna

Cost per

Upgrade Option X-band Perf. S-band Perf. Antenna X-band Valu

Increase Increase (FY 1982) in $M/dB4

Ultimate1 1.9 dB 1.4 dB $6,000,000 3.2

Intermediate2 1.4 dB 1.4 dB $3,300,000 2.4

Gravity3 Compn. 0.3 dB 0.0 $330,000 1.1

1. Ultimate: Extend 64-m to 70-m; shaped precision reflectors; gravity

compensation.

2. Intermediate: Extend 64-m to 70-m; shaped reflectors; gravity

compensation.

3. Gravity compensation: Braces and Y-axis correction to 64-m or 70-m

tipping structure.

4. For comparison, the arrayed addition of one new 34-m antenna to a

standard 64-m antenna provides approximately 1.3 dB performance

increase for a cost of $6.0M, as installed and equipped for X-band

reception only. The equivalent value is $4.6M/dB. However, the added

34-m antenna would provide a capability for simultaneous multiuser

support which is not given by the single, upgraded 64-m antenna

option.41

The 64-meter Antenna Rehabilitation and Performance Upgrade Project was establish

in September 1982 with D. H. McClure as project manager. The guidelines to the pro

ect manager were to “increase the technical performance of the 64-m antennas in term

of gain, efficiency, and reduced (radio) noise,” and to “carry out the rehabilitation 

the 64-m subnet.”

The following account of the execution and successful accomplishment of this task 

an abridged version of an unpublished report on the project by D. H. McClure an

F. D. McLaughlin.42

Overall program management was under the cognizance of the NASA Office of Spa

Operations. Responsibility for project management was assigned to the Office 

Telecommunications and Data Acquisition at JPL. Implementation responsibility w

22

The Voyager Era: 1977–1986
assigned by that office to the manager for the project, D. H. McClure. The personn

required to carry out the project consisted primarily of JPL employees with support fro

contractor personnel for some engineering, administrative, and documentation function

Major technical areas were monitored by cognizant specialist engineers assigned to th

project.

The project consisted of two main initiatives, rehabilitation and upgrade. The rehabi

tation task included repair of the hydrostatic bearing and replacement of the rad

bearing, at the Goldstone 64-meter antenna, and investigation and determination of th

cause of the tilt on the 64-m antenna at Canberra. The performance upgrade task involv

increasing the existing 64-m antenna diameter to 70-m, improving the stiffness of th

structure by modifying the structural braces, and improving the subreflector focus cap

bility by adding automatic Y-axis focussing. This latter task was eventually carried o

as part of the Mark IVA task.

In summary, the project costs were $3.8 million for the rehabilitation task and $4.1 m

lion for the upgrade task.

The rehabilitation task was completed at Goldstone by June 1984 and the DSS 43 t

investigation was completed in early 1985.

The upgrade task was completed and the (now) 70-m antennas returned to missio

operations service with 70-m performance as follows: DSS 63, July 1987; DSS 4

October 1987; DSS 14, May 1988.

Rehabilitation of DSS 14 Pedestal

The “hydrostatic bearing” assembly, which forms part of the azimuth rotation system

was a key feature of the 64-m antenna design. In this design, the 13.2-million-kilogra

rotating structure was supported by a film of high pressure oil approximately 0.25 m

limeter thick. The oil film formed the load-bearing medium between each of three “pad

that carried the entire rotating structure, and a large, horizontal circular steel “runne

bearing on which the shoes rotated in azimuth. The runner bearing had a finely machin

upper surface to support the pads and was itself supported by a massive circular co

crete pedestal. Between the upper surface of the concrete and the lower surface of th

runner lay a thick layer of grout which was supposed to provide a stable, imperviou

interface between the steel bearing and the concrete pedestal. The dimensions of th

components of the hydrostatic bearing were impressive. Each pad was approximately 

meter wide, 1.5 meter long, and 0.5 meter deep. The runner bearing was 24.4 mete

230

Uplink-Downlink: A History of the Deep Space Networ
in outside diameter, 1.12 meters wide, and 12.7 cm thick. The walls of the pedest

were more than one meter thick and were topped by a massive “haunch” 2.1 mete

high and 1.8 meters thick. The haunch provided the foundation for the grout and th

runner. A cross-section showing the hydrostatic bearing components, and the portion 

the concrete pedestal that was removed and replaced during the year-long rehabilitatio

task at Goldstone, is shown in Figure 4-15.

Throughout the life of the 64-m antennas, deterioration of the grout and the concre

had resulted in variations in the clearances between the pad and runner surfaces as th

pads moved around the runner during azimuth rotation of the antenna. On numero

occasions, the film height reached minimum value and the antenna was automatical

halted, bringing mission operations to a stop. The antenna was then out of service un

the faulty section of the runner could be repaired by jacking it up and inserting lon

tapered shims between the grout and the runner, or even replacing the grout itse

23

The Voyager Era: 1977–1986

Figure 4-15. Rehabilitation of the DSS 14 hydrostatic bearing and pedestal concrete, June 198

June 1984.
During the twenty-month period between January 1981 and August 1982, 12,500 hou

of effort were expended in maintaining the grout. By this time, the antenna was ope

ating with film heights at or near the alarm level (0.005 inch).

During the Voyager 2 Encounter with Saturn in August 1981, the unevenness in th

runner surface reached the safety limit. It was only by posting an engineer on the ante

na to personally monitor the film height that DSS 14 was able to complete its fin

tracking pass with Voyager. It was a very close call. After that, the antenna was out 

service for several weeks while temporary repairs were made. Had this problem occurr

a few weeks earlier, the Saturn Encounter would have been significantly affected. Reliab

operation of the antenna was essential to support not only the ongoing flight projec

but the also the Voyager 2 Encounter with Uranus in January 1986. It was clear th

drastic remedial measures were called for.

Over the years since the hydrostatic bearing problem first appeared, a great deal of stud

and analysis of the problem had been carried out in an effort to determine the fund

mental reasons for the failure of the load-bearing grout. This work led to the discove

in 1983 that the principal cause of the problem was not the grout but the concrete 

the pedestal region beneath the grout. Briefly, it was determined that the pedestal co

crete had deteriorated due to a chemical reaction between the aggregate and the cemen

The aggregate reacted with the alkali in the cement to form silica gel, which in tu

absorbed moisture, expanded, and caused microcracks in the concrete. The net resu

was a decrease in the stiffness of the concrete to the point where it was no longer ab

to provide the proper support for the hydrostatic bearing. Based on this and previo

engineering analyses, the decision was made to remove all the concrete in the haun

at DSS 14 and replace it with concrete of a new type of mix which would not be su

ject to the former aggregate problem.

In June 1983, the antenna was removed from service and repair of the pedestal an

refurbishing of the hydrostatic bearing had begun. The six-million-pound rotating stru

ture was raised and placed on temporary supporting columns to allow the hydrostat

bearing and the runner to be removed for rework. All the concrete in the pedestal haun

was then removed one section at a time by a four-person crew with jackhammer an

drills. Because of the enormous amount of reinforcing steel embedded in the concret

it took the crew about five days to remove a 40-foot-long section. As each section w

removed, the new concrete was poured and allowed to cure. When the new “haunc

was completed, the radial bearing was replaced and the hydrostatic bearing componen

installed and aligned. Final tests on the new type of concrete showed that the origin

232

Uplink-Downlink: A History of the Deep Space Networ
specifications for stiffness had been met or exceeded. Various phases of this work as 

progressed are shown in Figure 4-15.

The DSS 14 antenna was returned to service almost exactly one year after it was take

down for the pedestal rework. Raising the six-million-pound antenna, placing it on 

temporary support structure, removing the hydrostatic bearing and runner and remo

ing and replacing 450 cubic yards of high-strength concrete had been a monument

task. The task was completed on schedule, within budget, and without a lost-time acc

dent. As a result of this work, the DSS 14 pedestal was expected to provide excelle

support for the hydrostatic bearing for many years.43

DSS Azimuth Radial Bearing

While the work described above was in progress, another key element of the antenn

azimuth rotation system was also being repaired. This was the radial bearing.

The radial bearing consisted of a 30-foot-diameter steel ring surrounding a concrete co

lar at the top of the pedestal. A vertical wearstrip was attached to the runner to provi

a track for three wheel assemblies equally spaced and attached to the rotating alida

structure. The wheel assemblies, bearing on the vertical wearstrip and runner, maintain

the correct vertical axis of rotation for the entire antenna.

In the twenty years after the antenna was built, the grout behind the radial bearing ru

ner and wearstrip had deteriorated to the point where the risk of failure in the enti

radial bearing assembly was unacceptably high. Failure of this bearing would result 

many months of downtime for repair. Accordingly, the decision was made to take adva

tage of the current downtime to repair the radial bearing as well as the hydrostat

bearing. A new runner and wearstrip were fabricated and installed. It took several wee

to adjust and align the runner and wearstrip to be concentric with the center of th

antenna foundation. New grout was placed and cured for two weeks for maximu

strength. The wheel assemblies were removed and shipped to a contractor for refu

bishing. Despite some problems with correct realignment of the wheel assemblies durin

the reinstallation process, the work was completed successfully, on time, to support th

first rotation of the antenna on the new pedestal.

DSS 43 Pedestal

The final item in the rehabilitation task concerned the pedestal tilt at DSS 43 in Canberr

This had been discovered in 1973 and later attributed to nonuniform loading on th

23

The Voyager Era: 1977–1986
pedestal. When it was decided to expand the 64-m antennas to 70-meter diameter, 

special analysis was made with new data to determine the cause of the tilt and the pote

tial impact of the increased weight on the foundation. The ensuing report conclud

that the tilt was due to the presence of softer supporting soil and bedrock at the sou

side of the pedestal, compared to that which supports the pedestal on the north sid

The report further concluded that the soil had compressed to its maximum amoun

and that the proposed additional weight would not increase the tilt enough to be cau

for concern.

Antenna Performance Upgrade

The concept of enhancing the performance of the 64-m antennas had been studied f

many years. There were a number of options and alternatives available, each with 

own advantages in terms of performance, cost, and viability. Chief amongst the su

porters of this initiative was Robertson Stevens, a significant partner in the developme

and implementation of the original 64-m antenna at Goldstone in the mid-1960s. H

report on the evolution of large antennas in the DSN traces the course of these stu

ies from 1958 to the 1982 recommendation to proceed with the 70-m extension program

By 1983, with a solution to the problem of supporting Voyager 2 at Uranus (20 AU

in 1986, the DSN addressed the next question of how to support the mission at eve

greater distance, namely at Neptune (30 AU) in 1989. Using a metric called an ape

ture unit (Ap.U.), equivalent to the effective aperture of a DSN 64-m antenna with 

system noise temperature of 25 kelvin at X-band, Stevens showed that for the Neptun

Encounter, 10.92 Ap.U. would be required. The Uranus configuration had provid

only 5.25 Ap.U., 4.45 Ap.U. from an array of DSN antennas, and 0.8 Ap.U. from th

Parkes antenna. Where would the shortfall in downlink performance come from?

Drawing on a background of previous engineering studies, Stevens proposed to increa

the DSN contribution from 4.45 Ap.U. to 6.45 Ap.U. by upgrading the existing 64-

antennas for a gain of 1.65 Ap.U., and by adding a new high-efficiency antenna 

Madrid for an additional 0.35 Ap.U. The balance of 4.47 Ap.U. would be contribut

by non-NASA facilities consisting of the Parkes, Australia, 64-m radio astronomy ante

na, the very large array antennas of the U.S. National Radio Astronomy Observatory 

New Mexico, and the 64-m antenna of the Japanese Space Agency in Usuda, Japa

This approach was considered viable and cost-effective, and with the Voyager Neptun

encounter as the driving motive, planning for upgrading the three existing 64-met

antennas to 70-meter diameter, on that basis, went forward.

234

Uplink-Downlink: A History of the Deep Space Networ
Performance analysis studies had predicted that in terms of gain improvement relati

to the 64-m antennas, 0.6 dB would come from the microwave feed system, 0.5 d

from the precision surface of the subreflector and main reflector, and 0.8 dB from th

increased diameter, for a total of 1.9 dB or about 55 percent. Overall performance 

S-band would be about 0.5 dB less due to the fact that the reflector surface refineme

had little effect at the lower frequency.

Notwithstanding its importance to the Voyager Neptune Encounter, upgrading th

64-m antenna had many other technical advantages. The additional antenna gain appli

to the uplink as well as the downlink, affording a considerable enhancement of com

mand capability under adverse conditions. In a new navigation technique called ve

long baseline interferometry (VLBI), which involved two 70-m antennas alternate

tracking a spacecraft and a natural radio source such as a quasar, the increased sen

tivity of the 70-m antenna allowed a much wider choice in the selection of rad

sources that were suitable for this purpose. In arraying with smaller antennas, the si

nal from the larger antenna could be used to aid the carrier tracking of the sign

from the smaller antenna at or near signal threshold. Furthermore, while the cost 

extending the 64-m antennas to 70-m diameter was about the same as building a ne

34-m antenna, the cost per aperture unit was only about 60 percent as much. Final

estimates of the maintenance and operations cost for an additional 34-m antenn

amounted to $200,000 per year, while the costs for maintenance and operation of th

existing 64-m antennas were not expected to increase significantly by their enlarg

ment to 70-m diameter.

When the project began, it was estimated that modification of the 64-m antennas 

70-m would require about 12 months for each antenna, or three years if they were mo

ified in sequence. However, the demand for the antennas to support ongoing missio

was such that the time period for the entire job had to be reduced to fit the 18-mon

period following the Galileo launch scheduled for mid-1986, and the Galileo Pro

release scheduled for the end of 1987. This 18-month window was the only period 

the foreseeable future when the antennas could be taken out of service without signi

cant impact to in-flight missions. The challenge became one of finding a way to comple

the implementation in half the time it would take under normal circumstances.

Normally, an implementation task of this type would be done by a single contract

who would be responsible for the design, fabrication, erection, and testing. The le

time for this approach would run into many months. Instead, to save time, the desig

was done by JPL engineers with assistance in detail design from TIW Systems of Sunnyva

California. Except for the Australian antenna, JPL acted as the prime contractor for th

23

The Voyager Era: 1977–1986
major items on a build-to-print basis. In Australia, the fabrication of the structural el

ments and the quadripod and the erection work were contracted locally. In addition 

this time saving strategy, it was planned to return each 70-m antenna to service with 

gain performance at least equal to the 64-m antenna, and to perform the final fine-tu

ing to reach predicted 70-m performance later as the opportunity provided. 

For various reasons associated with the support of ongoing missions, particularly Voyag

and the upcoming Galileo launch, urgency of the work at Goldstone, the seasonal weat

er conditions at each site, and availability of subcontractors and equipment, it was decid

to carry out the antenna expansion work in this order: Spain, Australia, and Goldston

The way the plan eventually worked out is shown in the following table.

Summary of 64-m to 70-m Antenna Expansion Start and Finish Dates

Location Start Date Return to Operations with 70-m Performance

Madrid 1 Aug 1986 29 July 1987

Canberra 1 Feb 1987 21 Oct 1987

Goldstone 1 Aug 1987 1 June 1988

The loss of the Shuttle Challenger in January 1986 caused a delay in the launch of Galile

and as a result the eighteen-month downtime constraint was removed. This left the Voyag

Neptune Encounter in August 1989 as the next scheduled mission constraint. Howev

the project elected to hold to its June 1988 completion date for the last antenna at th

expense of some overlapping downtime between the Madrid and Canberra antennas.

Microwave Design Considerations

Working within the constraints of antenna diameter (70 m), existing feed location, an

existing 64-m antenna rib shape, DSN engineers designed a microwave optics syste

that would optimize each of these constraining parameters. An asymmetrically shap

subreflector of approximately 25 feet in diameter would optimally illuminate the ne

high-precision, shaped surface of the 70-m main reflector. Microwave energy, focuss

by the subreflector, would enter a single hybrid-mode horn, to feed the existing low

noise X-band maser. The choice of microwave feed was based on an existing, prove

design, and offered a performance and cost advantage over either the S/X-band fee

236

Uplink-Downlink: A History of the Deep Space Networ
horn designed for the 34-m high-efficiency antennas or the dual hybrid-mode ho

which had been used on the 64-m antennas.

The single hybrid-mode horn, mounted on the X-band Receive Only (XRO) con

would provide the ultimate in X-band receive performance. S-band receive and tran

mit capability would be provided by the existing dichroic plate and reflex fe

arrangement on the S-band Polarization Diversity (SPD) cone, while the third con

carried an X-band/K-band Receive (XKR) feed, used principally for radio and rad

astronomy purposes.

Measurements of RF efficiency and system temperature were made at each 64-met

antenna before it was taken out of service and again before it was returned to servi

after upgrade to 70 meters. That design objectives were met is plainly obvious from th

results given in the table below.

Summary of Measured Antenna Gain Before and After Upgrade

Gain DSS 14 DSS 43 DSS 63 All Ants.

(dBi) X-band X-band X-band S-band

64-m 72.33 71.94 71.91 61.40

70-m 74.17 74.10 74.28 63.34

Improvement +1.84 +2.16 +2.37 +1.94

The reasons for the differences between stations would be understood and corrected 

time progressed. But, as the project ended, the gain improvement of 1.9 dB had be

realized and all three antennas were back in service in time to meet the immedia

requirements of the Voyager 2 Neptune Encounter in August 1989.45

Kicker Braces

Before the 70-m expansion work on the two overseas 64-m antennas could begin, 

was necessary to install additional structural bracing or “kicker braces” on each ante

na. This additional bracing was required to mitigate the effects of gravitational deflectio

with consequent radio performance loss, as the antenna was moved in elevation. Th

modification that involved replacement of two short, existing knee braces with very su

stantial steel members, had proven very effective on the Goldstone 64-m antenna.

The modification to the Australian antenna was started in October 1984 and complet

six weeks later. S-band performance measurements on the antenna in January 1984 show

23

The Voyager Era: 1977–1986
a gain versus elevation curve which was similar in shape but 0.4 dB lower than the co

responding Goldstone data. The reason for the discrepancy was not clear. When the Spani

antenna was modified some months later, its gain versus elevation curve also differed fro

those of both DSS 43 and DSS 63. It was decided to defer any further investigation 

these discrepancies until after the 70-meter extension work had been completed.

Subreflector

The shaped subreflector for the 70-m antenna was almost 8 meters in diameter, about tw

meters deep, and 1.6 cm thick. It was constructed of six, cast aluminum panels, weld

together to form two large pieces, and then bolted together for machining. At the time, 

was probably the largest cast aluminum structure that had ever been built. It required stat

of-the-art casting, welding, and machining technology to achieve the desired asymmetric

surface shape, with an accuracy of 2.54 millimeters (mm). The three subreflectors were ca

and machined by specialty contractors in Spain. However, the Spanish contractors soon r

into technical problems with the casting and machining processes, and the resulting dela

to the work were compounded by transportation, economic, language, and cultural dif

culties. Early estimates of subreflector fabrication time changed from 27 weeks to 40 wee

and directly threatened the completion schedule for the Australian antenna.

A contingency plan involving fabrication of a reinforced plastic subreflector of the sam

weight, diameter, and mounting configuration as the aluminum subreflector, was p

into effect. The plastic unit, which had a surface of revolution rather than a shaped su

face, was covered with a fine, expanded aluminum mesh. Although its performan

would not be as good as that of the full aluminum subreflector, it would suffice to allo

work to be completed to the 64-m performance level at DSS 43. The plastic subrefle

tor was fabricated in California in two halves, shipped to the antenna site near Canber

and installed without incident.

Until the aluminum subreflector for DSS 63 arrived, a concrete weight was installed 

its place so that servo tests and counterweight adjustments could proceed on schedu

The subreflector eventually arrived in time for the RF testing to take place as schedule

Surface Panels

The surface of the 70-m antenna was over 4,185 square meters in area and was co

structed of 1,272 individual aluminum panels of 17 different sizes. Each panel could 

adjusted individually to conform to the desired antenna surface shape which, when com

plete, was accurate to 0.6 mm (root-mean-square) over the entire surface. The pane

238

Uplink-Downlink: A History of the Deep Space Networ
were made by a special new facility in Italy, using a metal-bonding process to produ

the high-precision panels to an rms tolerance of 0.1 millimeter. Apart from some cu

rency problems in 1987 caused by devaluation of the U.S. dollar, the work proceed

smoothly, and all three sets of panels were delivered to the sites on time.

Madrid Site Implementation

With the necessary scaffolding and a 500-ton crane in place, disassembly of the DS

63 antenna began on 1 August 1986. Spanish contractors had already fabricated an

delivered the quadripod and all the new structural elements needed to replace the o

ribs and extend the diameter to 70 m. Reinforcing for the antenna backup structu

and elevation wheel was to be welded in place. Additional counterweights would 

needed to balance the added weight of the new subreflector, quadripod, and prima

reflector. Three months into the job, the contractor advised JPL that the downtim

would have to be extended by eight weeks due to various accumulated delays in th

work. Efforts to recover the lost time proved futile. Since the antenna conversions we

planned to be done in serial fashion, this delay would seriously affect completion of th

Canberra and Goldstone antennas. It was decided to start the DSS 43 downtime on 

February 1987, as originally planned, even though this would mean that two 64-

antennas would be out of service simultaneously until DSS 63 was completed. At th

same time, the Canberra and Goldstone schedules were extended from six to eight mont

based on the Madrid experience. This decision was soon vindicated when the Challeng

accident in January 1987 resulted in a three-year delay to Galileo, leaving the Voyag

Neptune Encounter in August 1989 as the main driver for project completion.

The structure was complete and the 1,272 panels installed in mid-December 198

Alignment was delayed due to some of the worst winter weather in Europe in 100 yea

Using the concrete dummy weight for the subreflector, the counterweight was balanc

and the antenna servo systems tested and calibrated.

The aluminum subreflector finally arrived in March, and was installed on the quad

pod so that RF gain measurements could be made. The first set of results indicated 

serious deficiency in antenna performance. All 1,272 panels were readjusted with eve

worse results. This was a grave situation which had to be understood before the alig

ment work on the Canberra antenna could begin. An intense effort, called in DS

parlance a “Tiger Team,” set about analyzing the problem. The “kicker braces” we

tightened and another panel alignment was carried out using a new measurement tec

nique called holography. These actions were successful in assuring that the 70-m antenn

exceeded the performance of the 64-m by 2.1 dB.

23

The Voyager Era: 1977–1986
On this basis, the antenna was returned to service on 27 July 1987, with a plan to com

plete the final, more detailed measurements at a later date.

Canberra Site Implementation

Working under a somewhat different funding arrangement from the other two sites, 

was Australian rather than American contractors who provided the new rib trusses, rei

forcing steel, quadripod, counterweight, and services for erection of the Canberra antenn

With all material and equipment in place, the downtime started on 1 February 198

as scheduled. Work proceeded smoothly despite some loss of time due to misalignme

of the truss modules and a problem with mounting some of the surface panels.

Because the reason for the anomalous performance on the Madrid antenna had not bee

determined by the time the contractors were ready to start panel alignment on th

Canberra antenna, it was decided to set that antenna using holography for the fin

alignment settings. Although this time consuming effort added three weeks to the com

pletion date, DSS 43 was returned to service with 70-m performance on 21 Octob

1987. Although the measured antenna performance was somewhat less than that mea

ured at Madrid (attributed to the use of the plastic subreflector), it met the 70-

performance specifications and remained in operational service for over two years befo

finally being replaced by the aluminum version in December 1989.

Goldstone Site Implementation

The implementation of the 64-m to 70-m antenna extension at DSS 14 benefitt

immeasurably from the DSN experience at the other two sites. The U.S. contracto

had the structural material on site, ready for installation at the start of the downtim

set for 1 October 1987. There were no problems in aligning the trusses at Goldston

and the installation of quadripod, rib modules, and panels was quickly accomplished 

planned. The aluminum subreflector from the Spanish contractor finally arrived on-si

in February 1988. Since the “Tiger Team” had not resolved the Madrid antenna pe

formance anomaly by that time, it was decided to set the panels as had been done 

Canberra, with a rough setting first, followed by a holograph-aided procedure.

As a result of the experience gained in Spain and Australia, the final panel settings an

the gain and efficiency measurements were conducted without problems, enabling th

DSS 14 antenna to be returned to service with 70-m performance on 29 May 198

two days ahead of schedule. Various aspects of the antenna work described above a

shown in Figure 4-16.

240

Uplink-Downlink: A History of the Deep Space Networ
So ended the 64-m Antenna Rehabilitation and Performance Upgrade Project. When 

was finished, the DSN had a complete subnetwork of 70-m antennas whose perform

ance met or exceeded the design values under all conditions and whose serviceabili

had been vastly improved as a result of many years of continuous operational expe

ence. It met the mission support requirements of the Voyager 2 encounter of Neptun

in 1989 and would enhance the downlink and uplink for all flight projects thereaft

Nevertheless, this antenna would be the final chapter in the DSN relationship with lar

antennas. Studies had shown that larger antennas were associated with diminishing retur

in cost per/dB of performance gain.

The path to future enhancement of the downlink lay in the array of smaller, higher ef

ciency antennas, and the pursuit of other avenues of telecommunications technology, 

future events would show.

24

The Voyager Era: 1977–1986

Figure 4-16. Work in progress on the 60-m-to-70-m antenna extension at DSS 14, Goldston

December 1987.
NETWORKS CONSOLIDATION

In the past, the DSN managed by JPL provided tracking and data acquisition suppo

for NASA deep space planetary missions. Managed by Goddard Space Flight Cent

(GSFC), a similar service was provided for NASA Earth-orbiting missions by a worl

wide network of tracking stations known as the Spaceflight Tracking and Data Netwo

(STDN). GSFC had for some time been developing a replacement for the STDN whi

would consist of three geostationary satellites with a capability for tracking and rela

ing, to a single ground station, data from Earth-orbiting satellites with a periapsis of le

than 15,000 km. This new facility, called the Tracking and Data Relay Satellite Syste

(TDRSS), but known in general terms as the Space Network, became operational 

1984. The few remaining satellites with Highly Elliptical Earth Orbits (HEEO), whi

lay outside the TDRSS zone of coverage, were serviced by a portion of the STDN call

the ground network or GSTDN. Since the HEEO missions to be supported by GSTD

would have operational parameters that were in many respects similar to deep space m

sions supported by the DSN, the question naturally arose as to whether there was an

combination of GSTDN and DSN that could result in a more economical way of su

porting those missions that could not be supported by the TDRSS.

To address this question, NASA Headquarters commissioned a study to be carried o

jointly by representatives from its Office of Space Tracking and Data Systems (OSTDS

JPL, GSFC and the overseas Complexes. Known as the Networks Consolidation Workin

Group, this body first met in May 1979 and completed its study in October 1979.4

In this study, a consolidated network comprised of various elements from the prese

DSN and the GSTDN showed significant cost savings and greater capability than th

sum of the separate networks. This option was planned around the then-existing pla

for the next generation of DSN improvements called the Mark IVA Model, augmen

ed with GSTDN facilities and resources to support HEEO missions. A top-level overvie

of the DSN and GSTDN Network Facilities that would eventually comprise th

Consolidated Network is shown in Figure 4-17.

In January 1980, a Networks Consolidation Program (NCP) office was established, 

the Tracking and Data Acquisition (TDA) Office at JPL, as a consequence of NAS

approval of the recommendations of the Networks Planning Working Grou

Simultaneously, program offices were established at GSFC and in OSTDS at NAS

Headquarters. JPL and GSFC management and technical counterparts were identifie

and monthly working sessions were initiated. Based on the work of these groups, a ma

agement plan, transition plan, mission support plan, and a contingency plan were develop

242

Uplink-Downlink: A History of the Deep Space Networ
and published in 1981.47 Budgetary considerations, changes in requirements, the pote

tial mission set, antenna cost trade-offs, staffing, and implementation schedules becam

matters of great concern as the requirements and constraints of the Network Consolidatio

program were integrated with those of the Mark IVA program.

The major elements of the GSTDN and DSN which were to be consolidated were th

tracking antennas and their associated support facilities. The current location of these el

ments at Goldstone, Canberra, and Madrid is shown in Figure 4-13. In the existing Ma

III DSN, and also in the GSTDN, each antenna was associated with its own suppo

facilities and control room. (At the overseas complexes, the two stations share the sam

operations and control building.) In the Mark IV DSN, the fundamental elements 

each consolidated DSCC would consist of multiple antennas operated and controll

from a single Signal Processing Center (SPC). As far as economically possible, all ante

nas at each complex were to be colocated with the 64-m antenna to permit unattend

operations. Data output from each of the three complexes is routed from the SPC v

the GCF to the Central Communications Terminal (CCT) at JPL. The data are distri

24

The Voyager Era: 1977–1986

Figure 4-17. Elements of the DSN and GSTDN, 1982.

DSS 14

64M

DSS 11

26M

10.7 km

9 km DSS 12

34M

GDS

GSTDN

26M

9M

GOLDSTONE,

CALIFORNIA

10,600 km

DSS 42

34M

CONJOINT

STATIONS CONJOINT

STATIONS

CANBERRA,

AUSTRALIA

ORR GSTDN

26M

9M

5 km

DSS 44

26M

20 km

DSS 43

64M

MADRID,

SPAIN

DSS 62

26M

DSS 61

34M

GSTDN

26M

9M

MAD

DSS 63

64M

10 km

8,400 km

5 km
uted from JPL to the Network Operations Control Center (NOCC), the Mission Contr

and Computing Center (MCCC), and other Project Operations Control Centers (POCC

The 1981 Mission Support Plan considered the mission set for the years during whi

the Network Consolidation-Mark IVA Implementation Task would take place (1982–198

in the following way:

Deep Space Missions Earth Orbiter Missions

Active Missions Active Missions

Viking Lander International Comet

Pioneer 10, 11, 12 Explorer (ICE)

Voyager 1, 2

Planned Missions Planned Missions

Galileo Planned Missions Active Magnetosphere Particle

Tracer (AMPTE)

This set of missions would form the basis for the schedule and sequence in which th

huge implementation task would be carried out.

To minimize the impact to ongoing missions and to protect the critical mission read

ness dates for future missions, a set of “ground rules” was established. Implementatio

for both the consolidation effort and the Mark IVA effort would have to be plann

around these constraints. The “ground rules” included coverage for the Shuttle and Ear

satellites, and set the conditions under which a 64-m antenna or a 34-m antenna cou

be taken out of service for modification. This meant that both projects had to be accom

plished with no interruption of service to the flight projects. To satisfy these constrain

three separate and parallel streams of activity were planned:

First, an interim configuration would be implemented around the 34-m subnetwo

between March 1983 and February 1984 to support the two HEEO missions, AMPT

and ICE, beginning in March 1984. During this period, DSSs 12, 42, and 61 wou

be configured in sequence.

In parallel, a consolidation configuration would be implemented between March 198

and January 1985. In this period the actual consolidation aspects of the task would 

accomplished.

244

Uplink-Downlink: A History of the Deep Space Networ
Finally, while this work was in progress throughout the Network, the stream of activi

directed to completing the final Mark IVA configuration by mid-1985, in time to su

port the Voyager 2 encounter of Uranus in the following January, would be moving ahea

It began in June 1983 at Goldstone. All the existing Mark III equipment was install

in the DSS 12 Control Room to create an interim configuration. Ongoing mission ope

ations were conducted from there. Similar rearrangements of the equipment at DSS 4

and DSS 61 were made to create interim configurations at the overseas sites. This pr

vided one full subnetwork of antennas in the interim configuration to support ongoin

mission operations round the Network.

Under the Consolidation plan, the first antenna to be moved would be the 26-m ante

na from the GSTDN station at Honeysuckle Creek near Canberra (DSS 44). Startin

in March 1983, it would be dismantled and re-erected near the 64-m antenna on th

DSN Complex site at Tidbinbilla where it would be identified as DSS 46. GSFC wou

provide the necessary electronics equipment to support a single uplink and downlin

The data and communications circuits from DSS 46 would be routed through NASCOM

direct to the POCC at GSFC. The relocation was complete by January and Syste

Performance Tests verified the integrity of the station in July, and readiness to suppo

AMPTE in August 1984.

The 26-m antenna, DSS 16 at Goldstone, did not need to be moved. Microwave, an

later fiber-optic, links would be used to connect it to the new Signal Processing Cent

on the Goldstone Complex. The existing equipment would be reduced to a single uplin

and downlink with communications direct with the POCC at GSFC.

In January 1984, the second relocation of a 26-m antenna would begin. It was to 

moved from the GSTDN site at Fresnadillas, Spain, to a site near the 64-m antenna o

the DSN Complex at Robledo and identified as DSS 66. GSFC provided the electro

ics to support a single uplink and downlink, and communications circuits were rout

via NASCOM directly to the POCC at GSFC. The relocation was completed in Octob

and System Performance Tests verified the integrity of the station in January 1985.

With this move completed successfully, the tasks related to the Networks Consolidatio

phase were now accomplished.48

24

The Voyager Era: 1977–1986
MARK IVA IMPLEMENTATION

To accommodate the new Signal Processing Center (SPC10) at Goldstone, the existin

control room at DSS 14 had to be enlarged and modified. This work began as soon 

the interim configuration at DSS 12 had begun supporting mission operations. Wh

SPC 10 was under construction, DSS 14 was taken offline for repair work on the hydr

static bearing and repair work on the concrete pedestal. (Note: The existing contr

rooms at the two conjoint stations were already large enough for their SPC and no si

nificant modifications were needed.) A few weeks later, construction work began on DS

15, a new, 34-m high-efficiency (HEF) antenna, at a site close to both the DSS 1

antenna and the new SPC. Later that year work began on the construction of a sim

lar antenna—DSS 45 at the Canberra Complex.

The old DSS 11 Control Room at the Goldstone Pioneer site was reactivated as a mi

imum hardware test bed and called the Network Test Facility (NTF). It was used as 

staging area to assemble the equipment, get it turned on, and get the connections wi

the Local Area Network (LAN) working. This was the first time the DSN had used 

LAN, and there was some concern about moving from the familiar (but now obsolet

star-switch controller system and going into a new, unproven, LAN-based system.

A key factor in the Implementation Plan required each set of complex equipment to 

assembled and tested by the people who were going to use it. Teams from the Madr

and Canberra complexes arrived at Goldstone for this purpose. They were the ones wh

were going to install it and they had to understand it and learn how to use it. Th

were not reticent in expressing their opinion of the so-called “user-friendly” design. Th

Australian Team thought “user-surly” would be more appropriate.

By October 1984, DSS 15 had been completed and equipment installed, the Mark IV

design had been validated, and SPC 10 was completed. System Performance tests wi

DSSs 14, 15, and 16, and SPC 10 were started.

At the Canberra Complex, DSS 45 was completed, the Mark-IVA equipment install

in SPC 40, and System performance tests with SPC 40, DSS 43, and DSS 45 we

completed by January 1985. A photograph of the Canberra Deep Space Communicatio

Complex, taken in early 1985, is shown in Figure 4-18. The Signal Processing Cent

(SPC 10), 64-m antenna (DSS 43), 34-m standard antenna (DSS 42), recently com

pleted 34-m HEF antenna (DSS 45), and the re-located 26-m X-Y antenna (DSS 4

are clearly seen.

246

Uplink-Downlink: A History of the Deep Space Networ
A 34-m high-efficiency antenna at the Madrid Complex was not planned for this tim

and with the relocation of DSS 66 at the end of 1984, implementation of the Ma

IVA equipment into SPC 60 could begin immediately. System Performance Tests wi

SPC 60 and DSS 63 were completed in May 1985.

All that remained to complete the Mark IVA configuration throughout the Network w

to upgrade DSSs 12, 42, and 61, all still in the interim configuration, to the Mark IV

status. With these three stations added to those already integrated with the new SPC

the Mark IVA upgrade task would be completed.

The final configuration of the Mark IV Model DSN, which includes the antennas an

capabilities provided by the consolidation program, is shown in Figure 4-19.

24

The Voyager Era: 1977–1986

Figure 4-18. Canberra Deep Space Communications Complex, January 1985.
248

Uplink-Downlink: A History of the Deep Space Networ

Figure 4-19. The DSN Mark IVA-85 configuration.

DSS 1234-METER

DSS 1464-METERDSS 1534-METERDSS 1626-METERDSS 4364-METER

DSS 6364-METER

DSS 6134-METER

DSS 6626-METER

DSS 4234-METERDSS 4534-METERDSS 4626-METER

(DS/HEO)(DS)(DS)(HEO)

(DS)(DS/HEO)(DS)(HEO)

GOLDSTONE

SPC 10

CANBERRA

SPC 40

MADRID

SPC 60

(DS)(DS/HEO)(HEO)

NETWORK OPERATIONS

CONTROL CENTER

OTHER POCC’S

OTHER CENTERS

JPL CENTRAL

COMM TERMINAL

LEGEND:COMM - GROUND COMMUNICATIONS

DS - DEEP SPACE

DSS - DEEP SPACE STATION

HEO - HIGH EARTH ORBITER

POCC - PROJECT OPERATIONS CONTROL CENTER

SPC - SIGNAL PROCESSING CENTER

MISSION CONTROL

AND

COMPUTING CENTER

COMM

COMM

EARTH ORBITER

LINK

EARTH ORBITER

LINK

EARTH ORBITER

LINK

NASCOM TO/FROM GSFC

NASCOM TO/

FROM GSFC

COMM
There were four other elements of the DSN, which although not directly involved 

consolidation tasks were deeply involved in the Mark III to Mark IV transition. The

were the Ground Communications Facility (GCF), the Network Operations Contr

Center (NOCC), and the two test facilities, CTA 21 at JPL and MIL 71 at KSC. Th

transition plan for the GCF allowed the GCF to simultaneously support the existin

Mark III and the gradually evolving Mark IVA configurations. As the Mark IVA upgrad

were completed at the complexes the GCF communications channels were switched ov

to the Mark IVA GCF, and the old Mark III equipment was deactivated.

A similar approach was used for the NOCC, due to the need to support a hybr

arrangement of Mark III/Mark IVA, while the interim configuration was current in th

Network. Cut over to the Mark IVA NOCC was effected as each Complex came in

service in the Mark IVA configuration.

Both CTA 21 and MIL 71 contained single string Mark III equipment. At CTA 2

this was adequate for spacecraft compatibility testing, and hardware or software deve

opment associated with the interim configuration. In early 1985, when the validatio

and testing of the Mark IVA equipment at Goldstone was complete, one of the ne

Mark IVA strings from SPC 10 replaced the obsolete Mark III equipment. At MIL 7

the Mark III equipment would be used to support the AMPTE launch. Later, it wou

be replaced by Mark IVA equipment.

Inevitably, there were delays to the original schedule and changes to the original pla

Throughout its entire life, the Mark IVA project was adversely affected by attrition 

the original budget.

A typical 1982 budget profile against which the progress of the Mark IVA and Networ

Consolidation programs would be measured is illustrated in the table below:

Typical Budget Profile (1982)

Fiscal Year 1981 1982 1983 1984 1985 Total

Networks

Consolidation ($M) 6.5 21.5 20.4 16.1 5.3 69.8

Mark IVA ($M) 10.0 19.5 22.1 21.9 14.9 88.4

Total ($M) 16.5 41.0 42.5 38.0 20.2 158.2

Under constant pressure from the 1980 Reagan Administration, the NASA budget w

cut several times during the course of the NCP/Mark IVA program. These reductio

24

The Voyager Era: 1977–1986
inevitably impacted the funding available for the work in progress, resulting in programmat

changes, deferment of some tasks, and schedule delays. The DSN could only deal wi

this continuing condition by deleting planned capabilities from the original design.

Despite these setbacks, the program was completed in time to support the Voyag

Uranus Encounter in January 1986. There were many liens outstanding against the sy

tem and little time left for operations verification testing. It was mainly due to the hero

efforts and dedication of the operations and engineering people at the three complex

that the Mark IVA worked so well at the time it was needed.

It was the perception of those who were in the best position to know that the ultima

cost of the Mark IVA project, including the Consolidation elements, was 10 to 20 pe

cent less than the overall cost estimated in 1982. This, however, resulted from mandat

budget cuts met by deleting capabilities, rather than from DSN management or eng

neering processes.

Although there were some questionable features of the internal design, particularly 

the subsystem operation, the overall goal of centralized control was met and amp

demonstrated in the years that followed. The main purpose of the Mark IV Netwo

upgrade to centralized control was to reduce operations costs by reducing the numb

of operators required to operate each antenna. That this goal was successfully achiev

is shown graphically in Figure 4-20.

In retrospect, the conversion of the DSN Mark III Data System to the Mark IVA Mod

was considered, at the time, to be the most complex implementation project underta

en in the DSN since its inception, surpassing even the MDS effort of five years earli

Initiated in 1980, the objective of the Mark IVA project was to reduce operations cos

improve reliability and maintainability, and to increase telemetry reception capability f

the Voyager Uranus encounter and all subsequent planetary missions.

That these immediate goals had been achieved soon became evident in the successf

Uranus Encounter and the events that soon followed. The validation of the long-ter

goals became apparent as the DSN moved through the remaining decade and a half 

the century. Additions to the Mark IVA were made as the increasing mission set require

but the original concepts on which this major undertaking were based gave no cau

for reconsideration. It could well be said the Mark IVA-85 model was indeed the for

runner of the “modern” DSN.49

250

Uplink-Downlink: A History of the Deep Space Networ
Signal Processing Centers

The three Deep Space Communications Complexes (DSCCs) that composed the Ma

IVA DSN were located at Goldstone, California; Tidbinbilla near Canberra, Austral

and Robledo, near Madrid, Spain. There was one Signal Processing Center (SPC) an

four antennas at each of the DSCCs. (The fourth antenna, a 34-m high-efficiency typ

was added to the Madrid DSCC in 1987.) High-speed and wideband communicatio

circuits linked each complex to the Network Operations Control Center (NOCC) 

JPL. The necessary communications terminal and data transmission facilities at ea

Complex and at JPL were included in the Mark IVA DSN, shown in completed for

in Figure 4-19 on page 263.

Each antenna within a Complex had some locally mounted equipment—antenna dri

and control equipment, low-noise amplifiers, receiver front ends, and transmitters. Th

antenna pointing equipment, microwave instrumentation, transmitter control, receiv

and metric data were located at the SPC. The SPC also contained the equipment whi

could be assigned to any of the designated antenna “links,” such as the telemetry, com

mand, radiometric, radio science, and interferometry processing equipment. Nonassignab

equipment such as that required for frequency and timing, test and training, and glo

al communications was also located in the SPC. Equipment associated with the 26-met

25

The Voyager Era: 1977–1986

Figure 4-20. DSN antenna operating costs, 1980–2000. The data shows that the Mark IV

Network upgrade reduced antenna operations costs from over $3,000 per hour in 1980, when 

operators per antenna were required, to $2,400 per hour in 1990, when only 4 operators we

required. Further economies in operations costs lay in the future.
Earth-Orbiter link was not controlled from the SPC until a few years later when it, to

was integrated with the SPC.

In the Mark IVA Model, the Signal Processing Center at each DSCC was configur

to support the operation of each antenna individually, or to array any combination 

the antennas. A simplified block diagram of an SPC is shown in Figure 4-21.

Within each SPC, the equipment could be grouped into three “links” by operators wor

ing from the Link Monitor Console. Each “link” comprised the equipment necessary 

support one spacecraft with a downlink and uplink as required by the particular m

sion sequence. This included the antenna and equipment associated with the trackin

receiver, telemetry, command, radiometric, radio science, monitoring and communic

tions functions. Each “link” was then assigned to a particular spacecraft/mission by a

operator working from the Complex Monitor Console according to an established sche

ule. Other subsystems provided test support, frequency and timing, maintenance, et

252

Uplink-Downlink: A History of the Deep Space Networ

Figure 4-21. Signal Processing Center, Mark IVA configuration.

34-METER

34-METER

64-METER

ANTENNA

ANTENNA

POINTING

FREQUENCY

AND

TIMING

OPEN-LOOP

RECEIVER

RECEIVER COMBINER

SIMULATION

DATA

LOG

RADIO 

SCIENCE

VLBI

DATA

LOG

TELEMETRY

TRANSMITTER EXCITER COMMAND

RADIO

METRIC

COMM

DATA

LOG

LOCAL AREA NETWORK

LINK

MONITOR

CONSOLE

COMPLEX

MONITOR

CONSOLE

MONITOR AND CONTROL

DATA
Interactions between the two monitor consoles and the hardware and software com

prising the “links” were carried by an extensive Local Area Network.

Compared to the former Mark III configuration, this arrangement resulted in a ve

significant reduction in the number of personnel required to conduct continuous m

sion operations at each Complex. Improvements in operability, reliability, maintainabili

and the ability to reconfigure rapidly to work around anomalous situations, were soo

apparent. The objectives of the Mark IVA project had certainly been achieved.

The control and data processing equipment for the 26-m Earth Orbiter tracking station w

not integrated into the SPC. With the exception of the telemetry equipment which was upda

ed, the equipment remained as it was when the stations were transferred from the GSTD

to the DSN in 1983. These stations could support only one uplink/downlink at a time, b

a cross-support connection with the SPC enabled a spacecraft link through the 26-m ante

na to be processed by one of the “links” at the SPC. Likewise, a spacecraft link through t

34-m standard antenna at the SPC could be connected to the Earth Orbiter station for da

processing. Either of these operational arrangements was known as the “cross-support” mod

Mark IVA Network Operations Control Center

The Network Operations Control Center (NOCC) at JPL, was also upgraded as part 

the Mark IVA project. The NOCC Mark IVA configuration is shown in Figure 4-22

Data from the SPCs was transported by the GCF to the Central Communicatio

Terminal. There, the data was switched to the JPL Mission Control Center (for JP

missions) or to a remote Project Operations Control Center (for non-JPL Mission

The data was also routed in parallel to the NOCC, where data monitoring and ne

work control functions were performed. The data monitoring functions were perform

in the real-time monitor processors which were retained from the Mark III model b

upgraded with Mark IVA compatible software.

Mission support data products such as DSS tracking schedules, mission sequence of even

prediction data for antenna pointing, and setting uplink and downlink parameters, we

also generated in the NOCC and provided to the SPCs as required for mission suppo

The Network was controlled from the NOCC by station controllers who were provi

ed with suitable displays to enable them to carry out these functions. During the Ma

IVA period the physical arrangements in the NOCC were greatly improved by subs

tuting convex shaped monitor consoles for the original circular consoles. The

25

The Voyager Era: 1977–1986
254

Uplink-Downlink: A History of the Deep Space Networ

Figure 4-22. Network Operations Control Center, Mark IVA.

DATA

DATA

LOCAL AREA NETWORK

LOCAL AREA NETWORK

ERROR

CORRECTION

AND

SWITCHING

DATA

LOG

MONITOR

AND

CONTROL

WIDEBAND DATA

VLBI

HIGH SPEED DATA

REAL-TIME MONITOR PROCESSORS

MONITOR AND CONTROLDATA PATHS

• CCT = CENTRAL COMMUNICATIONS TERMINAL• NOCC = NETWORK OPERATIONS CONTROL CENTER

JPL

MISSION

OPERATIONS

NETWORK

COMM

EQUIPMENT

MONITOR

AND 

CONTROL

TRACKING TELEMETRY COMMAND

RADIO 

SCIENCE

VLBI

SPARE PREDICTS DISPLAY DISPLAY

NETWORK

PREDICTS

OPERATIONS

TO REMOTEMISSION OPERATIONSCONTROL CENTERS/PROJECT OPERATIONSCONTROL CENTERS
accommodated larger monitor screens (14-inch) arranged in two tiers of five, provid

better viewing conditions and increased the work capacity and physical comfort of th

individual controllers.

Mark IVA Ground Communications Facility

The communications links between the SPCs and the Central Communications Termin

(CCT) at JPL were also upgraded as part of the Mark IVA project.50 The GCF Ma

IVA model permitted a more cost-effective utilization of available circuits without lo

ing the flexibility to protect critical data. At each SPC, new communications processo

were now capable of multiplexing data from all of the antennas on the Complex (da

links) on to a single 224 kbps circuit for transmission to JPL. In addition, critical da

could be transmitted on a single 56 kbps circuit with error detection and correctio

from the Complex to JPL. Complete, error-free and gap-free records of all data tran

mitted from the SPC would be generated automatically by the Data Records Subsyste

residing in the Central Communications Terminal at JPL. This Intermediate Data Reco

tape file would be the end product, deliverable to each flight project as a permane

record of the data captured from each spacecraft during each tracking station pass. Futu

plans called for a modular expansion of the transmission data rate capability to 1,54

kbps, enabling error correction on all data transmitted from the complexes.

At Goldstone, new microwave links were required to connect DSS 12 to the new SP

10 now located 21 km away. Networks Consolidation added the former STDN statio

DSS 16, to the DSN and necessitating the construction of a new fiber-optic link, 

miles in length, to bring its baseband data to the Goldstone GCF communications te

minal for transmission to JPL.

Consistent with the future introduction of packetized telemetry, plans were made 

expand GCF capability to accept variable size data blocks which would be sized to mat

the characteristics of the data stream being transmitted. This capability would furth

contribute to Network efficiency by minimizing the amount of data conditioning nee

ed for ground transmission by the older Mark III system.

DSN Mark IVA System Upgrades

Mark IVA Telemetry

At the Deep Space Communication Complexes (DSCCs), the DSN Telemetry Syste

was changed in two major ways as a result of the Mark IVA implementation project

25

The Voyager Era: 1977–1986
First, the addition of baseband combining equipment allowed for the arraying of u

to seven antennas at each Complex. Arraying the 64-m antenna with two 34-m ante

nas in this way would provide a gain of 1.84 dB relative to the gain of a single 64-

antenna. The enhanced downlink performance derived from arraying was driven by th

Voyager project requirement for support during the Uranus Encounter where the DS

antenna array at CDSCC was supplemented with the 64-m antenna at the Parkes Rad

Astronomy Observatory.

Second, the telemetry system was configured to support up to three missions simult

neously, with one or two of them being highly elliptical Earth-orbiting (HEO) mission

In addition to these major changes in capability, the Mark IVA telemetry system pr

vided for demodulation of Manchester-coded data modulated directly on the carrier wi

coded data rates up to 211.2 kilosymbols per second (ksps). This capability would 

used by many of the HEO missions. For planetary missions, maximum likelihood deco

ing of short-constraint length convolutional codes and sequential decoding 

long-constraint length codes was provided. Precise measurement of received signal lev

and system noise temperature, was available to all DSN users.

At each Complex, new features oriented towards improved DSN operations includ

centralized control and real-time status reporting by the Mark IVA Monitor and Contr

System. Original data records produced by each of the four telemetry groups could 

played back to the NOCC when necessary by local manual control or by automat

response to GCF instructions from the Central Communications Terminal at JPL.

The principal features of the Mark IVA telemetry arrangement at a DSCC are show

in Figure 4-23.

At each Complex there was one 64-m antenna and two 34-m antennas. The 64-

antenna and 34-m standard antenna could receive an S-band and an X-band carri

simultaneously. The 34-m high-efficiency antenna could receive one X-band carrier on

The high system noise temperature at S-band made it unsuitable for deep space rece

tion at S-band. The telemetry data processing equipment was arranged in four group

each of which contained two data channels. Each channel could process one data strea

from either an HEO or deep space spacecraft depending on its capability. Hardware 

Groups 1 and 2 closely resembled the Mark III model. Hardware in Groups 3 and 

contained the new Baseband Assembly (BBA), which was a new design incorporatin

the baseband combiner, subcarrier demodulator, and symbol synchronizer functions. 

functional block diagram of the new BBA is shown in Figure 4-24.

256

Uplink-Downlink: A History of the Deep Space Networ
25

The Voyager Era: 1977–1986

Figure 4-23. Principal features of the DSCC Mark IVA Telemetry Subsystem.

2-CHANNELRECEIVER(1 S-BAND AND1 X-BAND)

BASEBAND PATCH PANEL 2-CHANNEL RECEIVER (1 S-BAND AND 1 X-BAND)

SUBCARRIERDEMODULATORASSEMBLY 1(SDA1)

SYMBOLSYNCHRONIZERASSEMBLY 1(SSA1)

SYMBOLSYNCHRONIZERASSEMBLY 2(SSA2)

UNCODED

UNCODED OR LONG-CONSTRAINT CODED

CHANNEL 2 - UNCODED

BASEBAND SIGNAL SELECTION

TELEMETRY GROUP 1

TELEMETRY GROUP 2

(SAME AS GROUP 1)

TELEMETRY GROUP 3

TELEMETRY GROUP 4

(SAME AS GROUP 3)

TELEMETRY SUBSYSTEM

Fig. 1. Telemetry System: DSCC block diagram

LONG-CONSTRAINTCODED OR UNCODED

MAXIMUMLIKELIHOODCONVOLUTIONALDECODERASSEMBLY (MCD)

SHORTCONSTRAINTCODED

TELEMETRYPROCESSORASSEMBLY(TPA)

TELEMETRYPROCESSORASSEMBLY(TPA)

ODR

ODR

SUBCARRIERDEMODULATORASSEMBLY 2(SDA2)

MAXIMUMLIKELIHOODCONVOLUTIONALDECODERASSEMBLY (MCD)

BASEBANDASSEMBLY(BBA)

SHORTCONSTRAINTCODED

CHANNEL 1

CHANNEL 1

CHANNEL 2CHANNEL 1

CHANNEL 2

1-CHANNELRECEIVER(1 S-BAND AND1 X-BAND)

RECEIVER/EXCITERSUBSYSTEM

64-mANTENNAXMIT/RCV34-mANTENNASTANDARD34-mANTENNAHIGHEFFICIENCY
In addition to performing the functions required to format the decoded data for tran

mission to JPL via the GCF, the Telemetry Processor Assembly (TPA) carried out th

functions required by the centralized Monitor and Control system.

The key characteristics of the Mark IVA 1985 Telemetry System are tabulated 

Figure 4-25.

Mark IVA Command

The existing Mark III store and forward command functions were carried forward in

the Mark IVA system. This design allowed mission operations controllers at JPL or oth

Mission Operations Centers to prepare large files of spacecraft commands in advan

and to forward them to the DSCC at the beginning of a spacecraft track for transm

sion at designated times. The system design provided elaborate and well-proven procedur

to protect command data file integrity during transfer to the DSN station as well 

bit-by-bit confirmation of proper radiation from the DSN transmitter.

In the Mark IVA model, the DSCC Command System utilized elements of the upgra

ed antenna, microwave, transmitter, receiver-exciter and monitor, and control subsystems

These capabilities were configured, controlled, and driven by the new Mark IVA Comman

Subsystem as shown in Figure 4-26.

Four identical strings of command processing equipment, each containing a com

mand processor assembly (CPA) and command modulator assembly (CMA), cou

258

Uplink-Downlink: A History of the Deep Space Networ

Figure 4-24. Functional block diagram for Mark IVA Baseband Assembly (BBA).

FROM 64-m

FROM 34-m

STANDARD

FROM 34-m

HIGH

EFFICIENCY

SPARE

BASEBAND

COMBINER

SUBCARRIER

DEMODULATOR

SYMBOL

SYNCHRONIZER

SUBCARRIER

DEMODULATOR

CONTROLLER

UNCODED OR

LONG CONSTRAINT

CODED DATA

UNCODED DATA

SHORT

CONSTRAINT

CODED 

DATA MCD

TPA

MONITOR AND

CONTROL SIGNAL

SYMBOL

SYNCHRONIZER

BASEBAND ASSEMBLY
25

The Voyager Era: 1977–1986

Figure 4-25a. DSN Mark IVA Telemetry System key characteristics. RF reception characteristics.

Parameter

Frequency Range, MHz

S-band 2270–2300 2200–2300 2200–2300X-band 8400–8440 8400–8500 8400–8500

Gain, dBi

S-band 61.7 56.1 55.8X-band 72.1 66.2 67.3

System Noise Temperature, KZenith

S-band with maser

Diplex 18.5 ± 3 27.5 ± 2.5Listen-only 14.5 ± 2 21.5 ± 2.5

S-band with FET

Diplex 130 ± 10Listen only 115 ± 10

X-band with maser 20 ± 3 25.0 ± 2.5 18.5 ± 2

Antenna

34-meter 34-meter 64-meter Standard High-Efficiency

+0.3-0.4

+0.3-0.7

+0.0-0.5

+0.6-0.6

+0.6-0.6

+0.5-0.8
260

Uplink-Downlink: A History of the Deep Space Networ

Figure 4-25b. DSN Mark IVA Telemetry System key characteristics. DSCC Telemetry Subsystem Channel (Groups 1, 2).

Functions Channel 1 Channel 2

Baseband Combining N/A N/ASubcarrier Demodulation 100 Hz to 1 MHz, 100 Hz to 1 MHz,

squarewave or sine wave squarewave or sine wave

Symbol Synchronization 6 s/s to 268.8 ks/s 6 s/s to 268.8 ks/sData Format NRZ-L, NRZ-M, Bio-L NRZ-L, NRZ-M, Bio-LSequential Decoding

K=24 or 32; 

R=1/2; N/A

frame length selectable;16 s/s to 20 ks/s

Maximum Likelihood

K=7; 

R=1/2 or 1/3 N/A

Convolutional Decoding 10 b/s to 134.4 kb/sUncoded 6 b/s to 268.8 kb/s* 6 b/s to 268.8 kb/s2* Record only with non-real-time playback above 250 kbps.
26

The Voyager Era: 1977–1986

Figure 4-25c. DSN Mark IVA Telemetry System key characteristics. DSCC Telemetry Subsystem Channel (Groups 3, 4).

Functions Channel 1 Channel 2

Baseband Combining Up to seven basebands N/ASubcarrier Demodulation 10 kHz to 2 MHz, 10 kHz to 2 MHz,

squarewave or sine wave squarewave or sine wave

Symbol Synchronization 4 s/s to 4 Ms/s 4 s/s to 4 Ms/sData Format NRZ-L, NRZ-M, Bio-L NRZ-L, NRZ-M, Bio-LSequential Decoding K=24 or 32; R=1/2; N/A

frame length selectable;16 s/s to 20 ks/s

Maximum Likelihood K=7; R=1/2 or 1/3 N/AConvolutional Decoding 10 bps to 250 kbps*Uncoded 4 bps to 500 kbps* 4 bps to 500 kbps** Record only with non-real-time playback above 250 kbps.
262

Uplink-Downlink: A History of the Deep Space Networ

Figure 4-26. DSN Command System Mark IVA, 1985.

FRONT-END AREA (FEA) SIGNAL PROCESSING CENTER (SPC)

DEEP SPACE COMMUNICATIONS COMPLEX (TYPICAL)

ANTENNAMECHANICALANDANTENNAMICROWAVESUBSYSTEMS

64-m

34-m STD

34-m HEF

26-m

400 kW20 kW20 kWS-BAND20 kWX-BAND(PLANNED)10 kWS-BAND

TRANSMITTERSUBSYSTEM

RECEIVEREXCITERSUBSYSTEM

DEEPSPACES-BAND

DEEPSPACE/EARTHORBITERS-BANDDEEPSPACEX-BAND

EARTHORBITERS-BAND

SPACECRAFTCOMMANDENCODER

26-m CONTROL CENTER

DSCC COMMAND SUBSYSTEM

COMMANDSTRING 4

LINK M&C

LINK M&C

LINK M&C

EXCITERSTATUS

TRANSMITTERSTATUS

COMMANDSTRING 2COMMANDSTRING 3

COMMANDMONITORANDCONTROL

AREAROUTINGASSY

CENTRALCOMMTERM.

ODR

DIGITALCOMMUNICATIONSUBSYSTEM

GROUNDCOMMUNICATIONSFACILITY (GCF)

FLIGHT PROJECTMISSION OPERATIONSCENTERS (MOC)

NOCCCOMMEQPT.

DISPLAYSUBSYSTEMCOMMANDSUBSYSTEMMONITOR &CONTROLSUBSYSTEM

SUPPORTSUBSYSTEM

NETWORKOPERATIONSCONTROLTEAM

NETWORK OPERATIONSCONTROL CENTER (NOCC)

COMMANDSTRING 1COMMANDPROCESSORCOMMANDMODULATOR

DISC

COMMAND

SWITCH 1 COMMAND

SWITCH 2

S-BAND
be connected via a switch assembly to the exciters of any of the S-band transmitte

associated with the 64-m or 34-m antennas as shown in Figure 4-26. At the prop

time for radiation, validated command data files previously stored on disk by th

CPA would transfer to the CMA for subcarrier modulation before being passed 

the appropriate exciter for generation of the command-modulated S-band carrier f

radiation by the selected transmitter. Suitable interfaces with the monitor and co

trol system provided for real-time status and configuration monitoring. Although th

DSN command system was limited by the available transmitters to S-band uplin

transmissions only, the need to provide an uplink on X-band for future missions w

recognized, and development work to that end was already in progress in the eng

neering sections.

Mark IVA Tracking

In 1980 and 1981, the DSN Tracking System Mark III-79 model had been extensive

modified to improve its performance, operability, and adaptability to support anomalo

spacecraft conditions (notably, the Voyager 2 uplink tuning problem).53 The addition 

a new microprocessor-based exciter frequency controller or Digitally Controller Oscillat

(DCO) in place of the former programmed oscillator (POCA) to the receiver-exciter su

system, provided a large repertoire of precision, time-dependent frequency ramp

controlled via the Metric Data Assembly or a computer terminal. Under the control 

the Metric Data Assembly, the DCO would generate the special uplink tuning necessa

to accomplish the special uplink tuning required to support the Voyager 2 spacecraft, 

well as standard tuning for all other spacecraft uplink operations.

The Meteorological Monitor Assembly transmitted non-real-time meteorological data 

the NOCC for use in calibrating radio science and VLBI observations.

The quality of ranging data generated by the Planetary Ranging Assembly, as the ang

lar separation between a spacecraft and the Sun decreases, was improved by the additio

of selectable higher frequency components to the range code and better filters to decrea

waveform distortion.

In the NOCC, older software used to generate frequency and pointing predicts for th

stations, based on a Probe Ephemeris Tape supplied by the flight projects. It was red

veloped to make better use of the capabilities of the Sigma V computers in the NOC

Support Subsystem (NSS).

26

The Voyager Era: 1977–1986
In the Mark IVA implementation, further improvements were made to most of the el

ments of the Tracking System, and all of them were integrated with the new DSC

Monitor and Control Subsystem (DMC) to provide centralized control for all subsy

tems and collection and distribution of the monitor data required by each subsystem

At the NOCC, a new, Digital Equipment Corporation VAX 11/780 processor w

added to perform two, key Tracking System functions. The first was an orbit dete

mination function, similar to that carried out by the JPL flight projects, but intend

specifically for DSN support of the new cooperative and reimbursable missions. Th

other was the predicts generation and distribution function previously carried out 

the Sigma V-based NSS. Using radiometric data generated by the tracking station

the NOCC Navigation Subsystem (NAV) could generate orbit data files and state ve

tors for use by the NSS, or for dissemination to flight project navigation teams, 

on a reimbursable basis to external users such as the European Space Operations Cent

located in Darmstadt, Germany; the German Space Operations Center 

Oberpfaffenhofen, Germany; and the Japanese Tracking and Control Center locat

at Tsukuba, Japan.

More than any of the other DSN systems, the Tracking System reflected the impact 

changes to existing hardware and software and procedures introduced by the Mark IV

implementation. The quality and quantity of the S-band and X-band radiometric da

being delivered to the flight projects, especially Voyager, in the immediate post Ma

IVA period was not satisfactory. In March 1985, a special team was formed to mon

tor performance and recommend changes to improve radiometric data delivery prior 

the Voyager Uranus Encounter in January 1986. Many changes to improve the ope

ability of the Mark IVA Tracking System were proposed and implemented over th

following months. By January 1986, the usable data return had improved to an accep

able level to meet the Voyager 2 encounter navigation requirements. The excellent quali

of the radiometric data provided by the DSN was considered to have been a strong co

tributor to the remarkable targeting accuracy of the satellite Miranda, as Voyager 

transmitted the Uranian system.

Over the next few years, several major new capabilities would be added to the DS

Tracking System. These would include an X-band uplink, Media Calibration Subsystem

the Sequential Ranging Assembly, and a real-time interface between the radiometric an

navigation delivery systems.

264

Uplink-Downlink: A History of the Deep Space Networ
AN ABRUPT TRANSITION

Unlike the gradual transition between the Viking Era and the Voyager Era, the tran

tion from the Voyager Era to the Galileo Era was marked by an abrupt and trag

event—the Space Shuttle Challenger disaster in January 1986. At that time, both th

Ulysses and Galileo missions had been included in the DSN mission set for the Voyag

Era for several years (see Figure 4-1). Both spacecraft were to be launched by the Spa

Shuttle using a high-energy, liquid-hydrogen fueled, Centaur G upper-stage combin

tion. They would be the first spacecraft to be launched from the Shuttle in this mann

Since both spacecraft were bound for Jupiter, both launches were planned to take adva

tage of the May 1986 Jupiter launch opportunity. The Ulysses launch window open

on 15 May, and the Galileo launch window opened on May 20. Agreements betwee

the two flight projects had been made for the resolution of conflicts for launch prio

ty (in case of launch pad delays) or overlap of view periods at the DSN tracking station

The DSN planned to support both missions with the recently completed Mark IV

network configuration, 64-m antennas, 34-m standard antennas, 34-m high-efficien

antennas and the newly consolidated 26-m antennas.

In January 1986, both spacecraft were well advanced in their prelaunch preparations 

Kennedy Space Center. At each of the DSN complexes, however, attention was focus

on the critical Voyager Uranus Encounter operations then in progress. At the same tim

a team from the DSN Operations Office at JPL was en route to each of the comple

es to discuss support for the Galileo and Ulysses launches later in the year. They h

reached Madrid when the news came. Two days later the Voyager spacecraft made 

closest approach to Uranus.

Although the weeks that followed were a period of great uncertainty and confusion 

NASA and the Galileo and Ulysses projects, DSN was not immediately affected. Voyag

and other inflight missions continued to receive DSN attention. Then, on 12 Februa

1986, both flight projects were informed that the planetary missions would not 

launched in May 1986, and they were directed to work towards the next Jupiter laun

opportunity in June 1987. The change for the missions affected the DSN much mo

significantly than was realized at the time, as subsequent events would show.

For various reasons, the launches did not take place. The reasons for the further defe

ment of the launches, their effect on the DSN, and the eventual accomplishment 

Ulysses and Galileo missions are discussed in chapter 5, “The Galileo Era.”

26

The Voyager Era: 1977–1986
Endnotes

1. Bruce C. Murray, Planetary Report XVII (Number 3, May/June 1997): 14.

2. Bruce C. Murray, Journey into Space (New York: W. W. Norton, 1989).

3. David Morrison and Jane Sanz, Voyage to Jupiter, NASA SP-439 (Washington, DC

NASA, 1980).

4. E. K. Davis, “Deep Space Network Preparation Plan for Mariner Jupiter Satu

1977,” Document 618-706, Jet Propulsion Laboratory, Mariner Jupiter Satu

Project Office (15 December 1976).

5. David Morrison and Jane Sanz, Voyage to Jupiter, NASA SP-439 (Washington, DC

NASA, 1980), pp. 58, 60.

6. Andrew J. Butrica, “From Engineering Science to Big Science,” chapter 11, NAS

SP-4219 (Washington, DC: NASA, 1998), pp. 251–56.

7. David Morrison and Jane Sanz, Voyage to Jupiter, NASA SP-439 (Washington, DC

NASA, 1980), p. 108.

8. J. E. Allen and H. E. Nance, “Voyager Mission Support,” TDA Progress Report P

42-53, July-August 1979 (15 October 1979), pp. 4–5.

9. N. A. Fanelli and H. Nance, “Voyager Mission Support,” TDA Progress Report P

42-54 September/October 1979 (15 December 1979), pp. 19–23.

10. M. R. Traxler, “Deep Space Network Preparation Plan for Voyager (Saturn)

Document 618-706, Jet Propulsion Laboratory, Voyager Project Office; Rev. A (2

March 1980).

11. N. A. Fanelli and H. Nance, “Voyager Mission Support,” TDA Progress Report P

42-61 November/December 1980 (15 February 1980), pp. 22–26.

12. Jet Propulsion Laboratory, Voyager Project Office, “Voyager Bulletin; Mission Stat

Report No. 52” (27 August 1980).

266

Uplink-Downlink: A History of the Deep Space Networ
13. Jet Propulsion Laboratory, Voyager Project Office, “Voyager Bulletin; Mission Stat

Report No. 57” (7 November 1980).

14. N. A. Fanelli and H. E. Nance, “Voyager 1 Mission Support (I), Voyager 2 Missio

Support (II),” TDA Progress Report PR 42-66, September/October 1981 (1

December 1981), pp. 24–29.

15. See endnote 2.

16. C. T. Stelzried, “The Venus Balloon Project,” TDA Progress Report PR 42-8

January-March 1986 (15 April 1986), pp. 191–98.

17. R. A. Preston and J. H. Wilcher, “The Venus Balloon Project,” TDA Progre

Report PR 42-80, October-December 1984 (15 February 1985).

18. J. M. Urech, A. Chamarro, J. L. Morales, and M.A. Urech, “The Venus Balloo

Project Telemetry Processing,” TDA Progress Report PR 42-85, January-Marc

1986 (15 April 1986), pp. 199–211.

19. K. M. Liewer, “Selection of Radio Sources for Venus Balloon-Pathfinder DDO

Navigation at 1.7 GHz,” TDA Progress Report PR 42-87, July-September 1986 (1

November 1986), pp. 279–84.

20. See endnote 16.

21. R. Stevens, “Implementation of Large Antennas for Deep Space Mission Support

TDA Progress Report PR 42-76, November/December 1983 (15 February 1984

pp. 161–69.

22. C. T. Stelzried and A. L. Berman, “Antenna Arraying Performance for Deep Spa

Telecommunications Systems,” TDA Progress Report PR 42-72, Octobe

December 1982 (15 February 1983), pp. 83–88.

23. J. W. Layland et al., “Interagency Arraying Study Report,” TDA Progress Report P

42-74, April-June 1983 (15 August 1983), pp. 117–48.

24. D. W. Brown et al., “Parkes-CDSCC Telemetry Array; Equipment Design,” TD

Progress Report PR 42-85, January-March 1986 (15 May 1986), pp. 85–110.

26

The Voyager Era: 1977–1986
25. R. Stevens, R. L. Riggs, and B. Wood, “Pointing Calibration of the Mark IVA DS

Antennas (for) Voyager 2 Uranus Encounter Operations Support,” TDA Progre

Report PR 42-87, July-September 1986 (15 November 1986), pp. 206–39.

26. Jet Propulsion Laboratory, Voyager Project Office, “Voyager Bulletin; Mission Stat

Reports Nos. 72-81.” See reports beginning 4 November 1985.

27. A. L. Berman and C. T. Stelzried, “Helios Mission Support,” TDA Progress Repo

PR 42-67 November/December 1981 (15 February 1982), pp. 18–24.

28. W. E. Larkin, “Tracking and Data Acquisition Support for the Viking 1975 Missio

to Mars; June 1978 to April 1980,” Jet Propulsion Laboratory Publication 82-1

(15 April 1982). D. J. Mudgway, “Tracking and Data Acquisition Support for th

Viking 1975 Mission to Mars; May 1980 to March 1983,” Jet Propulsio

Laboratory Publication 82-107 (15 May 1983).

29. R. E. Nevarez, “Pioneer 10 and 11 Mission Support,” TDA Progress Report PR 4

61, November/December 1980 (15 February 1981), pp. 17–21. D. Lozier, “Pione

Spacecraft,” personal communication, 1 August 1997.

30. G. M. Rockwell, “Pioneer 11 Saturn Encounter Support,” TDA Progress Report P

42-53, July/August 1979 (15 October 1979), pp. 10–20. R. B. Miller, “Pioneer 1

Saturn Encounter Mission Support,” Tracking and Data Acquisition (TDA

Progress Report PR 42-52, May/June 1979 (15 August 1979), pp. 4–7. R. B. Mille

“Pioneer 11 Saturn Encounter Mission Support,” TDA Progress Report PR 42-5

September/October 1979 (15 December 1979), pp. 24–27.

31. J. W. Layland, “ICE Telemetry Performance,” TDA Progress Report PR 42-8

October-December 1985 (15 February 1986), pp. 23–213. N. A. Fanelli and D

Morris, “ICE Encounter Operations,” TDA Progress Report PR 42-84, Octobe

December 1985 (15 February 1986), pp. 176–85.

32. J. P. Goodwin, “Usuda Deep Space Center Support for ICE,” TDA Progress Repo

PR 42-84, October-December 1985 (15 February 1986), pp. 186–96.

33. Jet Propulsion Laboratory, “Deep Space Network Mission Support Requirements

JPL Document D-787, Rev. O (July 1987).

268

Uplink-Downlink: A History of the Deep Space Networ
34. National Aeronautics and Space Administration, Office of Space Operation

“Reimbursable Policy for the Use of Ground Network Facilities,” Ground Networ

Division, Internal Document (19 April 1991).

35. National Aeronautics and Space Administration, Office of Space Communication

“Obtaining Use of Office of Space Communications (OSC) Capabilities for Spac

Suborbital and Aeronautical Missions,” NASA Management Instruction, NM

8430.1C (31 December 1991).

36. R. J. Wallace, personal interview with D. J. Mudgway (13 August 1997).

37. P. L. Parsons, “Antenna Microwave Subsystem (Mark IVA)” TDA Progress Repo

PR 42-79, July-September 1984 (15 November 1984), pp. 165–69.

38. M. F. Pompa, “The New 34-Meter Antenna,” TDA Progress Report PR 42-8

January-March 1986 (15 May 1986), pp. 127–38.

39. Jet Propulsion Laboratory, “Deep Space Network to Flight Project Interface Desig

Handbook,” DSN Document 810-5, Module TCI-30 (1997).

40. D. H. McClure and F. D. McLaughlan, “64 Meter to 70 Meter Antenna Extension

TDA Progress Report PR 42-79, July-September 1984 (15 November 1984), p

160–64.

41. R. Stevens, “Report on Maintenance, Rehabilitation, and Upgrade of the DSN 6

meter Antennas,” TDA Office Internal Memo (22 March 1982). B. Wood, “Repo

on the Mechanical Maintenance of the 70-Meter Antennas,” DSN Document 89

257, Jet Propulsion Laboratory, p. 5; Document D-10442 (31 January 1993).

42. D. M. McClure and F. D. McLaughlin, “64-m Antenna Rehabilitation an

Performance Upgrade Project Report,” private communication (13 August 1997)

43. D. M. McClure, “Repair of DSS-14 Pedestal Concrete,” TDA Progress Report P

42-81, January-March 1985 (15 May 1985), pp. 136–48. H. McGinne

“Rehabilitation of the 64-m Antenna Radial Bearing,” TDA Progress Repo

PR 42-65, July-August 1981 (15 October 1981), pp. 151–61.

44. See endnote 21.

26

The Voyager Era: 1977–1986
45. See endnote 42.

46. M. L. Yeater and D. T. Herrman, “Networks Consolidation Program,” TDA Progre

Report PR 42-59, July/August 1980 (15 December 1980), pp. 83–84. M. L. Yeate

and D. T. Herrman, “Networks Consolidation Program,” TDA Progress Report P

42-65, July/August 1981 (15 October 1981), pp. 19–24.

47. M. L. Yeater et al., Jet Propulsion Laboratory, Deep Space Network, “Networ

Consolidation Program Plans and Mark IVA Implementation Plans,” DS

Document 803-008, Vol. I, Management Plan (9 October 1980); Vol. II, Transitio

Plan (15 June 1981); Vol. III, Mission Support Plan (15 December 1981); Vol. I

Mark IVA Implementation Plan (15 May 1984); Vol. V, NCP Contingency Stud

(15 August 1981); Vol. VI, Mark IVA Contingency Plan (15 June 1983).

48. D. D. Gordon, “Mark IVA 26-Meter Subnet,” TDA Progress Report PR 42-7

July-September 1984 (15 November 1984), pp. 152–59.

49. R. J. Wallace and R. W. Burt, “Deep Space Network Mark IVA Description 1986

TDA Progress Report PR 42-86, April-June 1986 (15 August 1986), pp. 255–69.

50. R. A. Crowe, “The GCF Mark IV Implementation and Beyond,” TDA Progre

Report PR 42-82, April-June 1985 (15 August 1985). M. R. Traxler, Jet Propulsio

Laboratory, “Deep Space Network Preparation Plan for Voyager (Uranu

Interstellar Mission,” DSN Document 870-19 (1 April 1984).

51. D. L. Ross, “Mark IVA DSCC Telemetry System Description,” TDA Progre

Report PR 42-83, July-September 1985 (15 November 1985), pp. 92–100.

52. H. C. Thorman, “DSN Command System Mark IV-85,” TDA Progress Report P

42-84, October-December 1985 (15 February 1986), pp. 135–42.

53. J. A. Wackley, “The DSN Tracking System,” TDA Progress Report PR 42-6

March-April 1981 (15 June 1981), pp. 8–14. J. A. Wackley, “The Deep Spa

Network Tracking System, Mark IVA, 1986,” TDA Progress Report PR 42-8

January-March 1986 (15 May 1986), pp. 139–46.

270

Uplink-Downlink: A History of the Deep Space Networ
CHAPTER 

The Galileo Era: 1986–1996

271
THE GALILEO ERA 

A Defining Moment

Unlike the transition from the Viking Era to the Voyager Era, the transition to th

Galileo Era was clearly defined by the aftermath of a tragic event of great significan

to NASA in general and to the Deep Space Network (DSN) in particular. On 28 Janua

1986, 73 seconds after a perfect lift-off from the Cape Kennedy launch pad, the Spa

Shuttle Challenger exploded in full view of a worldwide television audience. The inve

tigation that followed would forever change the course of DSN support for the tw

major deep space missions of that time, Ulysses and Galileo.

At the time of this disaster, both the Galileo and Ulysses spacecraft were at Cape Kenned

being prepared for separate launches in May 1986, from the Challenger. After deplo

ment in Earth orbit by the Shuttle, both spacecraft would be injected into their individu

mission orbits towards Jupiter by NASA’s high-energy liquid hydrogen-fuelled Centa

booster rockets.

Both Ulysses and Galileo had been carried by the DSN as future missions for several yea

and DSN plans to support the May launches were well advanced. After reaching Jupit

Ulysses was to swing up and out of the plane of the ecliptic to enter a solar orbit pas

ing over the poles of the Sun. En route to Jupiter, Galileo would release an atmospher

Probe targeted to enter the Jupiter atmosphere at the same time as the spacecraft arrive

On arrival, Galileo would be inserted into an orbit around Jupiter from which it wou

first return the telemetry data from the atmospheric Probe before making imaging an

other science observations from numerous close encounters with the Jovian satellites.

Bruce Murray1 describes what happened next: “A presidential commission to investiga

Challenger’s demise was immediately formed. Chairman William Rogers soon conclu

ed that ‘the decision to launch was flawed.’ By then, a sobered NASA had alread

acknowledged that Galileo could not be launched in May 1986. Galileo and Ulyss

would have to slip at least thirteen months more, to June 1987, when Earth and Jupit

next would be in favorable locations” for a Centaur-based planetary launch. Meanwhi

based mainly on crew safety considerations, objections to the use of Centaur as a Shuttl

borne upper stage were increasing. In June 1986, the NASA Administrator canceled th

Centaur as a Shuttle payload. Without the Centaur, the 1987 missions were not pos

ble. The only option for an upper stage injection vehicle left to Galileo and Ulysses w

the much lower energy solid motor booster developed by the Air Force, called the Inert

Upper Stage (IUS).

272

Uplink-Downlink: A History of the Deep Space Networ
Ultimately, both Galileo and Ulysses were rescheduled for launching by the Shuttle 

October 1989, using the solid motor IUS as an upper stage injection vehicle. Exce

for dates, the Ulysses mission was not altered by this change; however, the Galileo m

sion was significantly changed in ways that materially affected the DSN. It became 

new mission. It would be referred to as the Venus-Earth-Earth-Gravity-Assist (VEEGA

Galileo mission, and it was planned for launch in October 1989, with Jupiter arrival 

December 1995. In April 1991, just over a year into the mission, an intractable pro

lem with the spacecraft high-gain antenna led to a complete redesign of the missio

once again. The timely DSN response to this potentially disastrous situation was a maj

factor in the ultimate recovery of the Galileo mission objectives.

Mission Set

These momentous events would cause the Galileo project to follow a path that wou

affect DSN engineering, implementation, and operations in a major way for the next t

years. For historical purposes, therefore, it is convenient to designate the period 1986–199

as the Galileo Era. The DSN mission set for the Galileo Era is shown in Figure 5-1.

Figure 5-1. Galileo Era Deep Space mission set.

Galileo Era

Deep Space Mission Set

1998

1997

1996

1995

1994

1993

1992

1991

1990

1989

1988

1987

1986

P6-9 P10 Vg2 Vg1 Uls GII Mgn MO MGS MP Cas LP HEO ICE NR GR RA Gio

Secondary Misions

Future Missions

Primary Missions

Galileo Era

27

The Galileo Era: 1986–1996
The following paragraph gives an overview of the Galileo Era mission set and missio

that it included. 

Overview 

Following successful flybys of Venus in 1985, the Vega 1 and Vega 2 spacecraft conti

ued on to close encounters with Comet Halley in March 1986. Renamed Pathfind

they relied on DSN tracking support to refine the orbit of Comet Halley for use b

Giotto and several other comet-bound missions in 1986. DSN support for all the fo

eign missions to Comet Halley in 1986 was provided on the basis of cooperative 

reimbursable agreements. 

Using radar techniques to penetrate the dense Venusian atmosphere, the Magellan missio

to Venus in 1989 observed and mapped the surface features of the entire planet. At th

end of its long extended mission, it gathered information on aerobraking techniques whi

would be of great value in the design of the future Mars Global Surveyor mission.

Mars Observer was launched in September 1992 and reached the vicinity of Mars 

August 1993. Three days before it was to be inserted into orbit for a Mars mappin

mission, the downlink was lost. Despite persistent efforts by the DSN, communicatio

with the spacecraft could not be restored. It was suspected that the spacecraft had bee

destroyed by an explosion in the retro-propulsion system.

Reflecting a renewal of scientific interest and a substantial constituency for Mars, tw

new Mars missions were launched in 1996. Both launches used expendable launch veh

cles. Mars Global Surveyor, a similar mission to the ill-fated Mars Observer, was launch

in November 1996. On arrival at Mars in August 1997, it was to use aerobraking tec

niques derived from the Magellan data to trim the initial orbit to the correct shap

before beginning a full global surface mapping mission.

Mars Pathfinder, launched in December 1996 was the first of the “faster, better, cheape

class of missions, which was to characterize the Cassini Era and the missions of the ne

millennium. Using a unique inflated “bouncing ball” system, its landing on the Mars su

face in August 1997 was to be the first since the Viking Landers’, twenty years earlier.

Towards the end of the Galileo Era, the first asteroid mission was launched. The p

mary objective of the Near Earth Asteroid Rendezvous (NEAR) mission was to orb

the near-Earth asteroid Eros in a 50-km orbit for the purpose of determining the gro

physical properties, mineralogical composition, and morphology of the asteroid surfac

274

Uplink-Downlink: A History of the Deep Space Networ
Launched in February 1996, it would arrive at Eros in January 1999 after an Ear

swingby in January 1998.

Throughout the Galileo Era, the DSN continued to support Voyagers 1 and 

International Cometary Explorer (ICE), and Pioneer 10 as extended missions.

By 1990, the number of Earth-orbiting missions for which the DSN was given respo

sibility had increased to the point where they were managed in the DSN schedulin

system as a unique class, termed high-Earth orbiter (HEO) missions. Mostly, these we

inflight missions which were more suited to the ground-based network of the DSN tha

to the space-based network of the Tracking and Data Relay Satellite System (TDRSS

At about the same time, the number of non-NASA spacecraft for which the DSN pr

vided tracking and data acquisition services on a reimbursable basis to NASA began 

increase significantly. These also were defined uniquely as “reimbursables” and were ma

aged within the DSN, independent of the deep space missions. From this point o

DSN resources were assigned according to predetermined priorities to the deep spac

HEO, and reimbursable missions.

We turn now to examine in more detail the remarkable events that took place in th

Galileo Era and the DSN involvement in all of them. The DSN transition to the Galil

Era began with its continuing support for the foreign missions to Comet Halley. 

27

The Galileo Era: 1986–1996
NETWORK OPERATIONS

Deep Space Prime Missions

The Comet Halley Missions

In “Journey into Space,” former Jet Propulsion Lab Director Bruce Murray describes h

intense efforts to interest NASA in a U.S. mission to Comet Halley in late 1985 an

1986. It would, he pointed out, be seventy-six years, the year 2061, before anoth

opportunity arose. Murray started lobbying early, in 1980, right after President Reaga

had taken office and media interest in JPL was still sparked by the stunning visual pro

ucts of Voyager’s encounter with Saturn. 

“Where is the United States headed in space?” Murray was asked. 

“Halley,” Murray replied. What Murray had in mind was a Halley Intercept Missio

(HIM), a NASA spacecraft that would intercept the comet’s path and photograph an

make scientific observations of the structure and composition of the Halley nucleu

Murray pushed hard for the support of Reagan’s new NASA administrator James Begg

presenting HIM as a “unique, affordable opportunity for NASA and the United States

At NASA Headquarters, the arguments went back and forth for months. Central to th

debates were the costs and scientific merit in light of other foreign missions alread

planned, and the rising demands of the Shuttle program for limited NASA funds. 

was all to no avail. In September 1981, NASA Headquarters officially directed JPL 

cease all further activity associated with the HIM. JPL would have to settle for th

United States mission then flying near Halley, ICE, or those observing from afar, Pionee

and for DSN support of the foreign missions. 

In discussing the DSN role in the Comet Halley missions in 1986, Charles Stelzrie

Leonard Effron, and Jordan Ellis wrote, “In man’s continual quest to explore and unde

stand the nature and origin of the solar system, 1985 through 1986 may well be not

as the ‘Year of the Comet.’ The first in-situ measurements of a comet occurred on 1

September 1985, with the passage of the International Cometary Explorer (ICE) throug

the tail of Comet Giacobini-Zinner, 7800 kilometers down-stream of the nucleus. Th

unprecedented encounter was followed six months later by the spectacular rendezvo

of a fleet of five spacecraft in the vicinity of Comet Halley during the four-day lon

period March 9-13, 1986. The Halley armada included Japan’s Sakigake (MS-T5) an

Suisei (Planet-A), the Soviet Union’s Vega-1 and Vega-2, and ESA’s Giotto. Twelve da

later, ICE also passed within Halley’s sphere of influence. In addition to the aforeme

276

Uplink-Downlink: A History of the Deep Space Networ
tioned six spacecraft, two other interplanetary explorers turned their instruments in th

direction of Comet Halley in 1986. The long-lived Pioneer 7 and the Venus-orbitin

Pioneer 12 contributed to the library of space-based measurements made during th

Halley exploration period . . . . It was also an unprecedented period in the arena 

international cooperation between national space agencies and the worldwide scientif

community.”2

Together with two other national space agencies, the European Space Agency (ESA) an

the National Space Development Agency (NASDA) of Japan, NASA (through the DSN

was a major contributor to the Comet Halley mission initiatives. The DSN provid

telemetry, command, and navigation support for Giotto in the near-Earth phase and f

the comet encounter. The DSN also provided telemetry, command, and navigation su

port for the near-Earth phase of the Japanese missions, as well as for the short perio

around the actual comet encounter. Following the completion of their Venus Pathfind

missions described in the previous chapter, the Soviet Vega-1 and Vega-2 spacecraft, 

order to improve their encounter orbit determination, made use of the Very Long Baselin

Inteferometry (VLBI) techniques that the DSN had used for the Giotto mission. Th

Comet Halley observations made by ICE, Pioneer 7, and Pioneer 12 were carried o

as part of the continuing DSN support for these missions.

Giotto

DSN support for the Giotto mission to Comet Halley in 1986 was provided on th

basis of a reimbursable agreement between the European Space Agency (ESA) and NASA

The Giotto spacecraft was a spin-stabilized vehicle that used S-band and X-band dow

links and an S-band uplink to communicate with the DSN antennas. The DSN committ

to providing telemetry, command, and navigation support for the near-Earth phase an

for the Comet Encounter. The uplinks and downlinks were fully compatible with DS

telecommunication standards, and there were no special or additional implementatio

requirements imposed on the DSN by the Giotto mission. It was recognized that th

late cruise and encounter periods in February and March 1986 would coincide with th

Uranus Encounter period of Voyager 2 and that schedule conflicts for DSN antenn

time were to be expected.

Giotto was launched aboard an Ariane-1 launch vehicle from Kourou, French Guian

on 2 July 1985, and it was injected into a heliocentric orbit by the spacecraft’s onboa

propulsion system the following day. DSN support began with DSS 46 at Canberr

Australia, as the initial acquisition station. For the next seven days, continuous suppo

was provided by the 26-m subnet and the telemetry and radio metric data was rout

27

The Galileo Era: 1986–1996
to the European Space Operation Center (ESOC) at Darmstadt, Germany, via JPL an

the NASA Communications (NASCOM) switching center in Madrid, Spain. After tha

DSN support was reduced to one pass per day on a 34-m antenna, DSS 12 or DS

42. Over a two-week period in mid-September 1985, the DSN participated with ES

in the first of several Navigation Campaigns to validate the radio metric data collect

by the ESA tracking stations. Radio metric data (two-way Doppler and ranging) fro

the station pairs DSS 12/42 and DSS 61/42 was provided in the form of Orbit Da

Files for comparison with the ESA data taken during the same passes. 

Preparations for encounter with Halley began in October with an extensive series 

rehearsals using Giotto as a data source and the actual sequences that would be us

during encounter. As the test progressed, anomalies were identified and corrected, an

the procedures and techniques were refined. Some changes were made to the data flo

paths for delivering the Madrid and Canberra data to ESOC. All Giotto data from the

sites would be routed to NASCOM at the Goddard Space Flight Center in Greenbe

Maryland, rather than to JPL. NASCOM would transmit the data directly to ESO

via satellite link. Because this configuration reduced the transmission path by 6,00

miles, it was expected to make a significant reduction in the number of transmissio

errors at the high encounter data rate of 46 kbps. The rehearsals and Navigation Campaig

passes continued right up to the start of the encounter.

The DSN responded to a Giotto spacecraft emergency in late January by making DSS 

available for support. However, the downlink from the distressed spacecraft was too we

for reliable telemetry data acquisition, and the project requested support from the Goldston

64-m antenna. DSS 14 was released from Voyager 2 support of Uranus encounter by neg

tiation between the Voyager and Giotto Project managers. Although this was its first suppo

of Giotto, the station was able to acquire the downlink signal and flow the telemetry eng

neering data to ESOC within 37 minutes for analysis. After it was determined that t

spacecraft antenna was mispointed, the ESA station in Carnarvon, Australia, was used 

transmit a corrective command when the spacecraft came into view at that longitude.

Three days of continuous support by the 64-m subnetwork to cover Halley’s Com

encounter events started on 11 March 1986 and was accomplished without inciden

Two seconds before the time of closest approach, the downlink signal was lost due 

mispointing of the spacecraft high-gain antenna. This was attributed to nutation of th

spacecraft spin axis induced by comet dust particles impacting the spacecraft. Althoug

nutation dampers on the spacecraft slowly compensated for this effect, 34 minutes 

close-encounter, real-time, telemetry data was lost. Some of this was later recovered fro

the digital recordings made at the tracking stations.

278

Uplink-Downlink: A History of the Deep Space Networ
Nevertheless, the project reported that the overall encounter results were spectacular an

that pictures had been obtained to within about 1,500 kilometers of the nucleus befo

the downlink was lost.3

Analysis by ESOC, using radio metric data from the DSN and the ESA Deep Spa

Tracking System (DSTS), augmented with the Vega-1 and Vega-2 Halley observatio

(described in the previous chapter) indicated a miss distance of 610 kilometers with a

uncertainty of 40 kilometers. 

An independent estimate of the spacecraft arrival time and position at Halley was deriv

at JPL from DSN radio metric data obtained during the final Navigation Campaig

(just prior to encounter). A predicted comet miss distance of 610 kilometers was obtain

with an uncertainty of 138 kilometers. The times of closest approach agreed to with

two seconds.

It was suggested that differences in the comet ephemerides and spacecraft attitude info

mation used by DSN and ESA could easily account for the small disagreement in th

miss distance solutions.4

Phobos

After a hiatus of some ten years following the Mariner and Viking missions to Ma

scientific interest in exploration of that planet resumed in 1988 with the Soviet Union

Phobos 88 missions. The USSR Space Research Institute (abbreviated IKI in Russia

in Moscow was the mission planning organization. More than a dozen countries we

involved in putting together the scientific payload. It would be the first internation

deep space initiative of any scope since the successful Halley flyby missions, Vega an

Giotto, in March 1986.

The mission was to be devoted to studying the planet Mars and its environment, pa

ticularly its natural satellite Phobos, which was thought to be an asteroid captured b

Mars. The study of Phobos was the prime scientific objective of the mission and w

to be conducted by means of two Landers on the Phobos surface. One of them, a lon

term automated Lander (abbreviated DAS in Russian), would carry celestial mechani

experiments, spectrometers, seismometers, and cameras. The other lander, called a “Hoppin

Lander” or “Frog,” was fitted with a jumping mechanism to allow it to move from pla

to place, analyzing the chemical composition and physical and mechanical properties 

the surface at each location.

27

The Galileo Era: 1986–1996
The Landers were to be deployed to the surface of Phobos from a “bus” spacecra

whose orbit had been carefully adjusted to be synchronous with that of Phobos. Th

bus would remain in synchronous orbit for about a month, making topographic

studies of Phobos before initiating the approach and Lander descent sequences. Th

bus was to descend to within 50 meters of the surface before releasing the Lande

to make individual, controlled descents to the surface. Once on the surface, th

Landers would begin their automated science missions, the DAS from a single fixe

location, the Frog from various locations determined by its 20-meter jumps. The b

would return to its circular orbit, from which it would observe Mars, the Sun, an

the interplanetary environment for a few months. The total duration of the missio

was to be fifteen months.

Communications with the spacecraft were planned for every five days during cruise an

every three days in the orbital phase. In the interval, data were to be recorded on boa

the spacecraft. The link with the DAS was to be established three times per day, on

during each orbit of Phobos, and last 20 to 40 minutes. The Frog would transmit 

data directly to the “bus” for recording and later retransmission to Earth.

The main receiving station was at Eupatoria in the Soviet Union. From there, data w

transmitted to IKI in Moscow for processing and distribution to the experimenters v

the French Space Agency, Centre National d’Etudes Spatiales (CNES), in Toulouse, Franc

DSN involvement in Phobos followed naturally from its involvement with the Vega an

Halley missions two years previously. Of particular interest to the DSN was the oppo

tunity that the Phobos DAS Lander provided for refinement of the ephemerides of Ma

and Phobos, and for improving the accuracy of the existing radio-to-planetary frame-t

measurements.5

Ranging measurements between Earth and the DAS Lander were to be used to dete

mine very precisely the orbit of Phobos around Mars. They would also improve curre

knowledge of the orbit of Mars, which had been most accurately determined prior 

this by the ranging measurements of the two Viking Landers from 1976 to 1978. Togeth

these measurements should allow the Mars orbit to be determined to an accuracy 

about 5 nanoradians, relative to the orbit of the Earth around the Sun. This was mu

better than the then-current level of knowledge of the “planetary reference frame.”

In addition to the Mars ephemeris improvement, the Phobos mission would also pr

vide a rare opportunity for delta VLBI measurements, which could be used to tie togeth

the “planetary” and “radio” reference frames used for interplanetary navigation.

280

Uplink-Downlink: A History of the Deep Space Networ
Each Lander had a “VLBI broadcast mode,” consisting of two coherent tones spac

14.71425 MHz apart on the downlink frequency of 1.7 GHz (C-band). In this mod

delta-VLBI measurements between a Lander and a nearby compact radio source in th

sky would locate the Lander, and therefore Phobos, in the “radio” frame. The rangin

measurements described above would be used to tie the positions of Phobos and Ma

together, so that the delta-VLBI data effectively placed Mars in the “radio frame,” ther

by completing the “planetary to radio” frame tie. It was on the strength of this argumen

and its importance to future JPL navigation technology, that the DSN went forwa

with plans to support the Phobos missions.

Apart from the problem of finding suitable compact radio sources for the delta-VLB

observations, no significant additional effort was required to meet the Phobos requir

ments for celestial mechanics. However, in two other areas, a very considerable effo

was required.

The Soviet-designed Phobos Landers were complex spacecraft capable of receiving com

mands, transmitting telemetry, providing two-way range and Doppler and supportin

delta VLBI measurements. Spacecraft-to-Earth communications were carried by a 1.

GHz (L-band) uplink and a 5.01-GHz (C-band) downlink.

During each Phobos-Earth view period, the Lander telemetry data was transmitted 

2,048-bit frames encoded in one of three different modes. One of these modes (co

volutional code, K = 6, r = 1/2) could be decoded using the standard DSN MC

capability. To accommodate the other two modes, special software was developed 

Madrid as a logical follow-on to the Venus-Balloon experience. This was then integra

ed into a Phobos telemetry data processor.6

Since neither the uplink nor the downlink frequencies were compatible with the DS

standard operating frequency bands, it was necessary to design and implement a spec

dual-frequency feed to handle simultaneous two-way communications with the Lande

The dual-frequency feed was composed of an L-band feedhorn enclosing a coaxial

mounted C-band surface-wave antenna.7 This feed geometry provided greater than 3

dB of isolation between the C-band uplink and the L-band downlink, and it could saf

ly handle 15 kW of uplink C-band transmitter power. The concept for this design w

derived from the L-band feedhorn that had been implemented at all 64-m antennas f

the earlier Vega and Halley missions.8 The way in which the horn was positioned in th

antenna to correctly illuminate the subreflector is shown in Figure 5-2. 

28

The Galileo Era: 1986–1996
Following the pattern of previous Soviet space projects, the Phobos mission compris

two nearly identical spacecraft. Each spacecraft was launched on a Proton launch veh

cle in July 1988 from Baikonour in the Soviet Union. Phobos-1 was disabled by a groun

control error before reaching Mars orbit. Phobos-2 completed the Earth-Mars transf

phase and was successfully inserted into an elliptical Mars orbit in January 1989. 

Using Soviet and French onboard imaging data supplemented with two-way Doppl

and VLBI data provided by the DSN, the complex process of changing the elliptic

spacecraft orbit to be circular and “synchronous” with the orbit of Phobos began. O

21 March, the spacecraft entered a nearly circular orbit with a period of 7.66 hou

which kept it close (about 275 km) to Phobos. On 27 March, without prior warnin

all communications with the Phobos-2 spacecraft were lost. Extended efforts to reesta

lish contact with the spacecraft were unsuccessful.

Despite the premature termination of the mission, all was not lost. A useful body 

Phobos frame-tie data had been obtained before the spacecraft was lost. The data co

sisted of two passes of VLBI observations of the Phobos-2 spacecraft and angularly nearb

quasars. The data was recorded with the DSN wide-channel bandwidth VLBI system

during an hour of observing passes on Goldstone-Madrid and Goldstone-Canberra bas

lines on 17 February and 25 March. Sparse though this data was, its subsequent reductio

and analysis yielded satisfying results for the “frame-tie” experiment. Prior to 1989, th

282

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-2. Phobos L-band feedhorn mounted on the 64-m antenna.

INCOMING SIGNAL

QUADRIPOD

SUBREFLECTOR

(REF)

INCOMING SIGNAL

L-BAND HORN

ASSEMBLY

XRO CONE

ASSEMBLY

TRICONE

ASSEMBLY

(REF)

PRIMARY

REFLECTOR

(REF)
planetary and radio source reference frames had been aligned with an accuracy of appro

imately 250 nanoradians. The analysis of the Phobos data reduced this uncertainty 

20 to 40 nanoradians, depending on direction.9

Background for Magellan

By the time the Galileo Era began, Venus was one of the most visited planets in th

solar system. Since the early 1960s, no less than twenty spacecraft from the United Stat

and the Soviet Union had carried out missions to Venus. Despite all that attention, the

existed only a sketchy, general knowledge of the planet’s surface because the dense, co

stant cloud cover precluded surface observations by conventional optical means. In th

late 1970s and early 1980s, the Pioneer Venus (U.S.) and Venera (USSR) spacecraft h

used radar to image its surface. Earth-based radar, too, had been used to penetrate th

clouds and provided valuable surface data, but this coverage was limited by the fact th

Venus always presented the same hemisphere to Earth view. Although these endeavo

had provided answers to many intriguing scientific questions and disclosed most of Venu

large-scale geography, they raised many more questions that remained unanswered.

To pursue these questions further, NASA planned to launch a new radar imaging spac

craft called Venus Orbiting Imaging Radar (VOIR) from the Space Shuttle in 198

The program was subsequently modified to defer the launch to 1988, and the missio

name became Venus Radar Mapper (VRM). The Challenger accident in 1986 forced 

further deferment of the launch to April 1989. The new Mission was called Magellan

The plan was for Magellan to arrive at Venus in August 1990, spend eight months 

orbit about the planet, and map most of surface at a resolution nearly ten times bett

than the resolution of existing surface maps. On arrival, the spacecraft’s rocket propu

sion system would be fired to inject the spacecraft into an elliptical orbit around Venu

After establishing the correct orbital conditions and checkout of the radar systems, th

science acquisition phase of the mission would begin. This phase would last 243 Ear

days or one Venus day, the time required for Venus to make one complete rotatio

under the elliptical orbit of the spacecraft. During the part of each orbit when the spac

craft was near the planet surface, the spacecraft would be oriented so that the high-ga

antenna pointed slightly to one side of the ground track, and the radar was turned o

The surface return data would be recorded on the spacecraft tape recorders until th

radar was turned off at the end of the mapping sequence about 30 minutes later. Altimet

and radiometer data were also to be taken during this period. 

28

The Galileo Era: 1986–1996
As the spacecraft moved further away from the surface toward apoapsis, it would be reo

ented to point the HGA toward Earth and the stored radar and spacecraft engineerin

data would be transmitted to the DSN. Playback, at a downlink data rate of 268.8 kil

bits per second, would take place in two periods of about one hour each, with an interruptio

of 14 minutes between them for a gyro star calibration. Data-taking on the succeedin

revolution would start about 10 minutes after completion of playback. 

These data-taking and playback cycles were to be repeated on each orbit, at regular inte

vals of three hours and nine minutes. Figure 5-3 shows these extremely busy orbit

activities and highlights the small margin of time between them.

On each successive orbit, the radar would scan a new swath of surface as the plan

rotated under the spacecraft orbit. Based on a very precise knowledge of the position 

the spacecraft determined from two-way and three-way Doppler data, the Synthet

Aperture Radar (SAR), altimetry, and radiometry data would be processed into imag

and maps for scientific study.

284

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-3. Magellan Venus orbit mapping profile. 

PLAYBACK

(57.1 MIN;

268.8 KBPS)

MOMENTUM

DESATURATION

DSN LOCKUP

(1.0 MIN)

STARCAL

(11.0 MIN)

PLAYBACK (64.8 MIN; 268.8 KBPS)

DSN LOCKUP (1.0 MIN)

TURN (6.0 MIN)

+80°

IDLE TIME ON

NORTH SWATH

(4.7 MIN)

IDLE TIME ON SOUTH 

SWATH (4.7 MIN)

+66°

PERIAPSIS

SOUTH SWATH

MAPPING RECORD

(37.2 MIN;

806.4 KBPS)

NORTH SWATH

MAPPING RECORD

(37.2 MIN; 806.4 KBPS)

APOAPSIS

ANGLES ARE TRUE ANOMALIES

ORBIT PERIOD = 3.15 HRS

PERIAPSIS ALT = 250 KM

TURN (5.0 MIN)

-80° -95°

SEQUENCE START

MARGIN (6.4 MIN)
Magellan Mission to Venus

The Magellan spacecraft was powered by two Sun-tracking solar panels and stabilized 

three axes using gyros and a star sensor for attitude reference. The spacecraft carried 

solid rocket motor for Venus orbit insertion, as well as a small hydrazine system for tr

jectory correction maneuvers and certain attitude control functions. Low-gain an

medium-gain antennas and a 3.7-m high-gain antenna (HGA) rigidly attached to th

spacecraft provided S-band and X-band uplinks and downlinks with the DSN. Th

HGA also functioned as the SAR mapping and radiometer antenna during orbital ope

ations. A separate horn antenna, for the radar altimeter, was fixed to the side of th

main body structure. A diagram of the Magellan spacecraft is shown in Figure 5-4. 

The capabilities of the DSN Mark IVA systems in 1989 were adequate to meet th

tracking and data acquisition requirements of the Magellan mission. However, the requir

ments for 70-m antenna time could not be fully met due to conflicting requiremen

from other high-priority missions such as Galileo, Ulysses, and Voyager 2. In such cas

where the 70-m antenna conflict could not be resolved through scheduling, Magella

was downloaded to an arrayed configuration of two 34-m antennas at the same loc

tion. Further economy in antenna usage was effected by making a small modificatio

to one of the two receivers at all 70-m and 34-m standard antennas, which allow

28

The Galileo Era: 1986–1996

Figure 5-4. Diagram of Magellan spacecraft in cruise configuration.

ALTIMETER HORN

EQUIPMENT BUS

(FROM VOYAGER)

STAR-48 SOLID ROCKET

MOTOR (PAM-D)

SOLAR ARRAY

(2 EACH)

PROPELLANT TANK

(FROM SHUTTLE)

FORWARD EQUIPMENT

MODULE

HGA (FROM VOYAGER)
both of the Magellan subcarriers to be received through a single X-band receiver cha

nel. Since Pioneer 12 was also in orbit about Venus, the second receiver channel at th

same antenna could then be used to pass the S-band Pioneer 12 signals.

The downlink coverage of important events associated with the launch and initi

acquisition sequence were the subject of an immense amount of planning and coo

dination by the DSN in the year or two preceding launch.10 DSN responsibility, 

this so-called “near-Earth” phase of the mission, was profoundly changed by the NAS

decision to use the Space Shuttle rather than the former expendable launch vehicl

for all future planetary launches. The original “near-Earth” planning for Shuttle launc

es was related to Galileo, since at that time, Galileo was to be the first of the planeta

spacecraft to use the Space Shuttle as a launch vehicle.11 As it turned out, Magella

became the first planetary spacecraft to use a Shuttle launch, and the successful trac

ing coverage, data flow, and generation of predicted data products during th

“near-Earth” phase of the first Shuttle-based launch would validate the thoroughne

of DSN planning. The interagency agreements, interfaces, and communication co

figurations developed for Magellan were used on all subsequent planetary launche

beginning a few months later with Galileo. 

The Magellan mission to Venus began on 4 May 1989, eleven years after the launch 

Pioneer Venus, the last planetary spacecraft to use an expendable launch vehicle. Magella

thus became the first planetary spacecraft to be launched from a reusable space vehic

and it was for JPL the first planetary mission since Voyager 1 in September 1977. 

After deployment from the Space Shuttle Atlantis cargo bay, the IUS/Spacecraft comb

nation coasted to the correct point for injection. At that point, the two-stage IUS inject

the spacecraft into an Earth-Venus transfer orbit with an arrival date of 10 August 199

The spacecraft then separated from the spent IUS, and initial acquisition of the Magella

downlink was accomplished without incident by the first viewing, using DSN 26-m an

34-m antennas at Canberra.

Mapping began in September 1989 and continued for three cycles of 243 days eac

During this period, Magellan mapped over 98 percent of the Venus surface. The sta

tling detail produced by the Magellan SAR data is obvious in the image of an impa

crater in the Atalanta Region of Venus, reproduced in Figure 5-5.

In January 1992, partway into Magellan’s third cycle, one of two telemetry modulators o

the X-band downlink from spacecraft transmitter A failed, leaving the spacecraft unable 

transmit the high-rate mapping data. The S-band downlink and telemetry performance we

286

Uplink-Downlink: A History of the Deep Space Networ
not affected. In an effort to continue the mapping mission, the project switched back 

transmitter B. However, transmitter B, which had been used earlier in the mission, had 

history of generating spurious signals and noise which severely degraded its normal use f

transmitting the mapping data. Various schemes to continue the transmission of the ma

ping data at lower data rates were tried with varying degrees of success. Finally, mapping w

ended on 14 September 1992, and the radar was turned off on the fourth cycle. Transmitt

B continued to provide low-rate engineering data on the X-band downlink, and the S- an

X-band Doppler data were used to obtain a high-resolution global gravity field map.

Between cycles 4 and 5, the existing elliptical orbit necessary for radar mapping was mod

fied to near circular for gravity studies by aerobraking and propulsive maneuvers. This w

the first time an interplanetary spacecraft had used a planet’s atmosphere to significant

change a spacecraft orbit. The then-new technique was used very effectively until almost t

years later, when a new generation of lightweight spacecraft began to arrive once more 

Mars. Repeated aerobraking maneuvers rapidly reduced the orbital period from over 3 hou

to 94 minutes, and its apoapsis altitude from 8,469 kilometers to 542 kilometers. With t

near-circular orbit, Magellan could collect high-resolution gravity data over the poles, an ar

28

The Galileo Era: 1986–1996

Figure 5-5. Magellan SAR image of an impact crater in the Atalanta Region of Venus. 
for which there was no previous data. A gravity field map covering 95 percent of the glo

resulted from the fifth and sixth cycles. In addition to the gravity field measurements, du

ing several occultations that occurred during this period, Magellan performed bistatic rad

experiments to measure the specular reflection of the radio signal from the surface, and rad

science experiments to determine the characteristics of the atmosphere, ionosphere, and inte

planetary medium. The DSN was an integral part of all of these activities.

Due to funding limitations that precluded continuing the mission further, Magellan w

intentionally destroyed by an aerobraking maneuver that caused the spacecraft to ent

the atmosphere on orbit number 15,032, near the end of the sixth cycle. All subsy

tems remained functional to the end, albeit with some loss of redundancy. The la

confirmed downlink contact with Magellan was made by DSS 65, Madrid, at 10:04:3

UTC on 12 October 1994. This was almost five and a half years after the first dow

link contact with the DSN following its launch in May 1989. 

In retrospect, the Magellan mission was an enormous success, returning more data tha

all other planetary missions combined. Despite difficulties with the X-band downlin

toward the end of the mission, the mapping data return from the mission far exceed

the primary mission objectives. Over 98 percent of the planet was imaged at resolutio

as small as 75 meters, and a high-resolution gravity map covering more than 95 pe

cent of the planet surface was generated.12 

Voyager at Neptune

The year 1989 was a most notable year for space exploration in general and the DS

in particular. The notable events of 1989 began in January with the arrival of the Sovi

spacecraft Phobos-2 at Mars. In February, the third and final satellite in the new Trackin

and Data Relay Satellite System (TDRSS) was placed in geosynchronous Earth orbit. Th

Magellan launch in late April marked the first new planetary spacecraft launch in the 1

year period since the 1 launch in 1977. It was also the first planetary spacecraft to 

launched on the Space Shuttle. In June, the Voyager Neptune Encounter period bega

The spacecraft made its closest approach to the Neptune surface in August, and the prim

mission continued through September. The second Space Shuttle launch of a planeta

spacecraft took place in October with the Galileo spacecraft bound for Jupiter. The ye

ended with the long-awaited launch of the Hubble Space Telescope in December. Th

DSN was involved to a greater or lesser extent in all of these events. Here, we discu

the Voyager Neptune Encounter, in which the DSN was involved in a major way.

288

Uplink-Downlink: A History of the Deep Space Networ
The Neptune Encounter would be Voyager 2’s closest encounter with any of the plan

tary bodies in its twelve-year journey through the outer solar system. The close flyb

had been designed to maximize science observations of the planet’s magnetic field, charg

particles, and deep atmosphere, as well as to bend the flight path close to Triton, wh

limiting the risk of radiation damage to the spacecraft. Figure 5-6 shows the Neptun

Encounter geometry. 

While the previous Uranus Encounter took place at a spacecraft-to-Earth range of abo

20 AU, the distance to Earth would be about 30 AU for the Neptune Encount

Although the spacecraft would be 1.6 billion kilometers (1 billion miles) further fro

the antennas of the DSN, it was necessary to keep the downlink telemetry rates abo

the same as were used at Uranus in order to return the vast amount of science data th

was expected from this very unique event. How was this to be accomplished?

28

The Galileo Era: 1986–1996

Figure 5-6. Encounter geometry for Voyager 2 at Neptune.

Voyager 2’s closest approach to Neptune on August 25 (GMT) will be about 3,000 miles

above the planet’s cloudtops. Five hours later, the spacecraft will fly within about 23,900

miles of the moon Triton.

VOYAGER 2 AT

NEPTUNE

CLOSEST

APROACH

NEPTUNE

EARTH AND SUN

OCCULTATION

ZONES

VOYAGER 2 AT

TRITON

CLOSEST

APPROACH

TRITON SUN

AND EARTH

OCCULTATION

ZONES

EARTH AND SUN

-3H

-2H

-1H

+1H

+3H

+5H

+7H
Two techniques were to be employed—data compression on the spacecraft, and ante

na arraying in the DSN.

In the spacecraft, the telemetry data was modified by editing and compression tec

niques to reduce the number of data bits needed to transmit a full-size image witho

loss of resolution. This improvement in the efficiency of information content of the da

stream was carried out in the Flight Data System before the telemetry signal was tran

mitted from the spacecraft.

On Earth, the signal-gathering sensitivity of the DSN had been significantly increased b

the enlargement of the 64-m antennas to 70-m antennas in 1987. Further improveme

could be obtained by arraying 34-m antennas with the 70-m antenna at each Comple

The Uranus encounter had demonstrated the efficacy of adding the 64-m Parkes ante

na to the CDSCC array in order to enhance the DSN capability even further at th

longitude. The Neptune Encounter required all of that and more. Plans were made 

supplement the 70-m/34-m Goldstone array with the 27 (25-m) antennas of the Nation

Radio Astronomy Observatory’s (NRAO) Very Large Array (VLA) facility in Socorr

New Mexico. In addition, the 70-m antenna of the Institute for Space and Astronautic

Science (ISAS) at the Usuda Observatory in Japan was to collect radio science data 

sync with the DSN stations and the Parkes Radio Astronomy antenna in Australia. Th

would happen during the periods when the spacecraft passed behind the rings, Neptun

and Triton as viewed from Earth. The telemetry modulation was to be turned off du

ing these complex occultation sequences to provide maximum power in the S-band an

X-band downlinks to enhance the quality of the radio science data. 

By August 1988, the Goldstone-VLA link had been installed and progressively check

at the maximum general science and engineering data rates of 14.4 kbps and 21.6 kb

that would be required during Encounter operations. System performance tests with th

new in-flight software verified the design parameters, and gave confidence that the co

rect downlink signal-to-noise ratios, error rates, and signal margins were being achieve

Much remained to be done before the DSN was fully ready for encounter, but a revie

of the Ground Data System in February of that year found that progress to that poi

was satisfactory.

At the beginning of 1989, Voyager 2 was 4.36 billion km (2.71 billion miles) fro

Earth—299 million km (186 million miles) from Neptune. The Radio Science Tea

was completing an eight-week period of solar occultation observations, and both th

DSN and Voyager Operations Teams were engaged in intensive testing and training exe

cises to ensure maximum readiness for the encounter events. Bright cloud features h

290

Uplink-Downlink: A History of the Deep Space Networ
begun to appear on the Neptune images and, with the exception of the well-understoo

receiver problems, the spacecraft was in good health.

In April, a large dark spot rotating round the planet in 17 to 18 hours was detected 

the growing detail of the Neptune images by the Imaging Team.

The readiness of all elements of the DSN to support the encounter was reviewed agai

in depth, on 1 June. The review included the Canberra, Madrid, and Goldstone Complexe

the NOCC, GCF/NASCOM, Very Large Array, Parkes Radio Telescope, and the Usu

Deep Space Station. It was determined that with minor exceptions, all the new cap

bilities were in place and had been demonstrated, including the new interagency capabiliti

and interfaces. The review also found that appropriate arrangements were in place f

dealing with personnel or equipment contingencies and protecting the sites against rad

frequency interference, and that the operations crews had demonstrated an acceptab

level of operational competence. The DSN was declared ready.

As defined by the Mission Plan, the Neptune Encounter period began on 5 June 198

81 days before closest approach. The first 62 days were called the “observatory phas

and consisted of continuous observations of the Neptune system combined with nume

ous pre-encounter checkouts and calibrations of the science instruments. By the tim

the “far encounter” phase began on 6 August, the spacecraft had reached the point whe

the image of the planet and the rings required at least two narrow-angle camera fram

to cover them. Detailed ring and satellite imaging began, and infrared observations 

Neptune were made. As Voyager 2 approached the planet, imaging scientists were ab

to track the features in the clouds to determine wind speeds.

The “Near Encounter” period, from 24 to 29 August, contained the highest value Neptu

science data. It included a close swing over Neptune’s north polar region, a flyby of th

satellite Triton, a view of distant Nereid, numerous magnetic field measurements, an

searches for other possible rings and satellites. Voyager passed 4,900 kilometers (3,00

miles) above the cloudtops of Neptune and, five hours later, passed within 40,000 kil

meters (25,000 miles) of Neptune’s largest moon, Triton. 

The five-day “near encounter” period was covered by all three of the DSN complex

at various times. The complicated arrayed antenna configurations at VLA-Goldston

(VGTA) and Parkes-Canberra (PCTA) both operated perfectly to return the high-vo

ume engineering and science data at the desired downlink data rates of 14.4 and 21

kilobits per second.

29

The Galileo Era: 1986–1996
292

Uplink-Downlink: A History of the Deep Space Networ

The remarkable images of Neptune and Triton reproduced in Figures 5-7, 5-8, and 5

are typical of the period. They were made possible by (among other things) the prec

sion of the Voyager navigation and the high quality of the telemetry downlink. Both 

these depended on the DSN for their realization.

Voyager 2 discovered six new moons and a number of rings at Neptune. It found an ama

ing assortment of icy terrains and a form of ice volcanism on the surface of Triton. Rad

science occultation data from the DSN, Parkes, and Usuda antennas were used to chara

terize the atmospheres and ionospheres of Neptune and Triton and to investigate the structu

of the rings system. Celestial mechanics determined the gravity field of the planet and t

Figure 5-7. Voyager 2 views three most prominent features of Neptune. Although Neptune 

the smallest of our solar system’s four gaseous planets, its volume is nearly 58 times that of Ear

Three of the most prominent features in Neptune’s atmosphere are captured in this photogra

reconstructed from two images taken by Voyager 2. At the north (top) is the Great Dark Spot. 

the south of the Great Dark Spot is the bright feature “Scooter,” so-named because it rotat

around the globe more rapidly than the other features. Still further south is the feature called “Da

Spot 2,” which has a bright core. 
masses of its satellites. National Geographic described the Neptune Encounter events as “Voyage

Last Picture Show”13 and the Voyager mission as the “Voyage of the Century.”14

Once past Neptune, Voyager 2 continued to observe the Neptunian system on a contin

ous basis for five more weeks until early October 1989. Observations of the dark side 

Neptune and calibrations were carried out during the post-encounter period. Although th

was Voyager 2’s last planetary encounter, the spacecraft continued to return data on ma

netic fields and particles and to make other science observations in space as it joined Voyag

1 and Pioneers 10 and 11, moving toward the edge of the solar system and beyond, in

interstellar space. It would now be known as the Voyager Interstellar Mission and wou

remain a presence in the DSN “inventory” of deep space missions for many years to com

29

The Galileo Era: 1986–1996

Figure 5-8. Voyager 2 views south polar cap of Triton. Triton, Neptune’s largest moon, is abo

two-thirds the size of Earth’s Moon and orbits Neptune at about the same distance as the Mo

orbits Earth. Nearly two dozen individual images were combined to produce this comprehens

view of the Neptune-facing hemisphere of Triton. The large south polar cap at the bottom of t

image is highly reflective and slightly pinkish in color.
The Neptune Encounter was over, and the DSN was changing its focus once again 

the beginning of a new planetary mission to follow where Voyager 2 had gone ten yea

earlier. It was the long-delayed Space Shuttle launch of the Galileo mission to Jupite

Background for Galileo 

Carried forward by the dramatic successes of the Viking Mars Landers and the Pione

and Voyager flybys of Jupiter in the mid-1970s, JPL proposed an ambitious mission 

Jupiter for the 1980s. Known as Jupiter Orbiter Probe (JOP), the spacecraft combin

a powerful orbiter with an atmospheric entry probe and would be launched directly 

Jupiter by a Titan-Centaur expendable launch vehicle. However, late in 1975, NAS

decreed that all new planetary missions would use the Space Shuttle, and at the tim

of its approval by Congress in 1977, JOP was to be the first mission to do so. In Janua

294

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-9. Voyager 2 views Neptune and Triton. This dramatic view of the crescents of Neptu

and its largest moon Triton was acquired by Voyager 2 about three days after its closest approa

to Neptune. The spacecraft was then 4.86 million kilometers (3.01 million miles) from Neptune, a

5.22 million kilometers (3.24 million miles) from Triton. The smallest details discernible are appro

imately 90 kilometers (60 miles) in size.
1978, JOP became officially known as the Galileo Mission to Jupiter and was sche

uled for launch in January 1982 on the thirtieth Shuttle flight. For a direct flight 

Jupiter, the Galileo spacecraft would need the high-energy, liquid hydrogen-fuelled Centa

as an upper stage. The spacecraft, with attached Centaur, would be deployed into Ear

orbit by the Shuttle. At the proper time, the Centaur would be fired to inject Galil

into a direct trajectory towards Jupiter. That was the plan, but it never materialized

Over the next six years, the Galileo project became reluctantly involved in a series 

NASA changes to the Shuttle launch schedule and performance, as well as changes 

the availability of a suitable upper stage. Each of the changes, none of them due 

the Galileo spacecraft itself, necessitated a change to the mission design, with cons

quent impact on the supporting services required, including the DSN. Despite th

de-moralizing effects of so many changes on the technical design teams at JPL, th

tenacity of Galileo Project Manager John Casani held the critical elements of the pro

ect together. In that period alone, the Galileo mission was redesigned three times befo

reaching the final version destined for a May 1986 launch. This version would use th

Centaur upper stage to achieve a direct ascent trajectory to Jupiter, with arrival tw

years later in August 1988.15 

That plan, too, never materialized. The Galileo spacecraft had been shipped from JP

to Cape Kennedy in December 1985, while preparations for its planned Shuttle-Centa

launch the following July were in progress. In January 1986, the Space Shuttle Challeng

exploded shortly after launch and, in the aftermath of the ensuing enquiry, Centa

was cancelled as a Shuttle payload. For the fourth time, the Galileo mission had to 

redesigned. 

What emerged from this effort was to be called the Galileo Venus-Earth-Earth-Gravit

Assist (VEEGA) mission. VEEGA would be launched in October 1989 with a lower-ris

but also lower-energy upper stage called an Inertial Upper Stage (IUS). Since the ene

gy available from the IUS was insufficient to take Galileo directly to Jupiter from Ear

orbit, VEEGA would take advantage of the gravitational fields of Venus and Earth 

make up the deficit. After leaving Earth orbit, Galileo would fall inward towards th

Sun to intercept Venus in February 1990. The Venus flyby was designed to accelera

Galileo back toward a close Earth flyby in December 1990. A similar maneuver wou

use Earth’s gravitational field to accelerate Galileo into a wide orbit round the Sun f

a second and final gravitational assist from Earth two years later, in December 199

Then, Galileo would finally be moved in the right direction and with sufficient ene

gy to reach Jupiter in December 1995, six years after leaving Earth. The convolute

VEEGA trajectory is shown in Figure 5-10.

29

The Galileo Era: 1986–1996
The Galileo spacecraft was to consist of an Orbiter and an atmospheric Probe arrang

as a composite unit as shown in Figure 5-11. 

The Probe would enter the Jupiter atmosphere for the purpose of determining the com

position and structure of the atmosphere as it descended through the various clou

layers. The Orbiter was to be inserted into Jupiter orbit for the purpose of making obse

vations of the Jupiter system, including its satellites, during the 22-month prime missio

Though there were grand plans for the original Galileo mission to Jupiter, the actu

mission, due to unforeseen circumstances, was carried out in quite a different way, 

we shall see. From the time of its launch in October 1989 until the planned HG

deployment in April 1991, the Galileo spacecraft relied on S-band (2.3 GHz) uplin

and downlinks for its telecommunications support by the DSN. These links were us

for telemetry, command, navigation, and radio science. After the HGA deployment, th

mission was to have used the X-band (8.4 GHz) capabilities of both the spacecraft an

the DSN to provide the additional telecommunications link performance margin requir

to meet all of the mission objectives at maximum Earth to Jupiter range.

296

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-10. The Galileo Venus-Earth-Earth-Gravity-Assist (VEEGA) Trajectory.

FLYBY (1)

DEC 8, 1990 FLYBY (2)

DEC 8, 1992

LAUNCH

OCT 18, 1989

AUG 27, 1991

GASPRA

OCT 29, 1991

ASTEROID

BELT

PROBE

RELEASE

JUPITER

IDA

AUG 28, 1993

FLYBY

FEB 10,

1990

VENUS

ARRIVAL

DEC 7, 1995

LAUNCH

VENUS E 1 E 2 PROBE

RELEASE

TIME TICKS, days

SPACECRAFT 30

EARTH 30

VENUS 30

JUPITER 100

IDA

JUPITER

10/18/89 2/10/90 12/08/90 10/29/91 12/08/92 8/28/93 12/07/95 11/07/97

GASPRA
However, when the antenna was unlatched in April 1991, the unthinkable happene

The antenna failed to unfurl properly and, despite intensive efforts over the followin

two years to free what appeared to be a stuck element of the unlatching mechanism

the HGA remained unusable. The X-band downlink was useless.

In February 1993, a decision was made to redesign the mission using the available low

gain antennas (LGAs) to support the existing S-band uplinks and downlinks. DSN an

spacecraft engineers hastened to initiate design and implementation plans to provide th

new capability that would be needed to conduct orbital operations in 1996 and 199

on the S-band LGAs.

Five months before arriving at Jupiter, the Galileo Probe was released from the spac

craft to continue its trajectory directly to the point of entry into the Jupiter atmospher

A few days after releasing the Probe, the Orbiter carried out a deflection maneuv

29

The Galileo Era: 1986–1996

Figure 5-11. The Galileo spacecraft cruise configuration. In the composite spacecraft diagra

the high-gain antenna (HGA) is shown in its unfurled position. At launch, the antenna is stowed in 

“furled” position, rather like a closed umbrella. At a suitable point in the mission, when gravitation

forces and solar conditions are appropriate, a latching mechanism is released to allow the HGA 

slowly unfurl into the parabolic shape required for it to perform as an antenna. This antenna is a k

element in the spacecraft’s X-band downlink communication channel to the DSN 70-m antennas 

Earth. Without it, an X-band downlink is not possible. Without an X-band downlink, the High Ra

Telemetry Data Channel, on which the entire mission depended for its prime science data return, 

not possible.

LOW-GAIN

ANTENNA

NO. 1

ENERGETIC

PARTICLES

DETECTOR

HIGH-GAIN ANTENNA

(COMMUNICATIONS AND

RADIO SCIENCE)

PLASMA-WAVE

ANTENNA

LOW-GAIN

ANTENNA NO. 2

PROBE RELAY ANTENNA

JUPITER ATMOSPHERIC PROBE

RTG

SCAN PLATFORM, CONTAINING:

PHOTOPOLARIMETER RADIOMETER

NEAR-INFRARED MAPPING SPECTROMETER

SOLID-STATE IMAGING CAMERA

ULTRAVIOLET SPECTROMETER

SUN SHIELDS

STAR SCANNER

THRUSTERS

RADIOISOTOPE

THERMOELECTRIC

GENERATOR (RTG)

ABOVE: SPUN SECTION

BELOW: DESPUN SECTION

DUST DETECTOR

PLASMA SCIENCE

MAGNETOMETE

SENSORS

RETROPROPULSION MODULE
to place it on a trajectory that would overfly the Probe during its entry and descen

When the Probe reached that point, it entered the Jovian atmosphere. After survi

ing the deceleration forces and deploying a parachute, it descended through th

atmosphere, making scientific observations as it passed through the cloud layers. Th

data was transmitted on an L-band radio link to the Orbiter, which was in view 

the Probe as it descended through the cloud layers. The Orbiter relayed a small sam

ple of this data directly to Earth as it was received from the Probe during its descen

To ensure that the critical Probe data was preserved, the Orbiter also recorded th

full set of Probe data for later retransmission to Earth. After the Probe relay sequen

had been completed, the Orbiter used its retropropulsion engine to insert itself in

permanent Jupiter orbit. A diagram of the complex arrival sequence is shown 

Figure 5-12.

With the successful recovery of the full set of Probe data, the first set of mission obje

tives had been accomplished. The remainder of the Galileo mission was directed towa

the accomplishment of the second set of mission objectives, namely, the study of th

Jupiter system including its satellites.

298

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-12. The Galileo Orbiter and Probe arrival at Jupiter, 7 December 1995.

EUROPA ORBIT

9.5 RJ

IO ORBIT

5.9RJ

PROBE TRAJECTORY

ORBITER TRAJECTORY

EARTH

RELAY

JUPITER

46m JOI

45m

75m

4h

SUN
Jupiter orbital operations began in December 1995, immediately following Jupiter Orb

Injection (JOI). For approximately the next two years, the Orbiter would make scie

tific observations of the Jupiter system, including imaging from eleven close encounte

with the Jupiter satellites Ganymede, Callisto, and Europa. The modifications and improv

ments that had been made to the S-band downlink as a consequence of the failed X-ban

antenna were fully validated. The new science data returned by the spacecraft exceed

the most optimistic expectations of the scientists.

The Galileo prime mission officially ended in December 1997, with the spacecra

in fully operable condition. By that time, a proposal to extend the mission for a

additional two years to further study Europa had been approved. DSN capabiliti

required to support the extended mission were somewhat less than those required f

the prime mission, and on this basis, the Galileo Europa mission went forward in

the Cassini Era.

Galileo Mission to Jupiter

This was to be the second deep space mission to use the Space Shuttle as the laun

vehicle (Magellan was the first). The Shuttle-Centaur launch in May 1986 would ha

placed Galileo on a direct ascent trajectory to Jupiter, with arrival two and a half yea

later in December 1988. The change from the former expendable type of launch veh

cle to the Space Shuttle necessitated major changes to the procedures and data flo

configurations used by the DSN to provide the project with telemetry and comman

links with the spacecraft during the launch and Earth-orbit period. This was largely d

to the events associated with the Shuttle onorbit phase and the direct launch involv

ment of additional NASA Centers, including Johnson Space Center in Texas and Lew

Research Center in Ohio.16

The DSN planned to support the 1986 Galileo mission with the Mark IVA confi

uration described in the previous chapter. The Galileo downlinks would be on S-ban

and X-band, and all complexes could support the downlink telemetry rates from 4

bits per second to 134 kilobits per second. The normal uplink would be on S-ban

with 20-kilowatt transmitters at the 34-m stations and 125-kilowatt transmitters 

the 64-m stations. However, the DSN planned to demonstrate the then-new X-ban

uplink technology for command, Doppler, and ranging purposes by means of 20-kil

watt X-band transmitters located at the high-efficiency (HEF) antennas only. Th

command data rate for S- and X-band would be 32 bits per second. The Netwo

planned to support the launch and cruise phases of the Galileo VEEGA mission wi

the configuration shown in Figure 5-13.

29

The Galileo Era: 1986–1996
Network loading studies had identified many conflicts for Network support in 1988 an

1989. These conflicts were due to the combined requirements of Galileo at Jupit

Voyager at Neptune, and Ulysses in solar orbit, together with requests for extended 6

m support from ICE and Pioneers 10 and 11. It was anticipated that these would 

resolved as the mission progressed. In addition to long-term conflicts, the ESA spac

craft, Ulysses, was also at the pad preparing for a Shuttle-Centaur launch. Resolution 

the Ulysses and Galileo competing requirements for launch priority had been documente

In January 1986, the Network stations were completing tests to verify the operation

configurations of hardware and software that would be required for the forthcomin

Galileo mission. The new and complicated inter-Center interfaces needed to deliv

spacecraft telemetry to the project at JPL through the Shuttle phase were being va

dated. The spacecraft radio system had been checked for full compatibility with th

DSN frequencies, receivers, and transmitters. The DSN was ready to proceed to th

final prelaunch phase.

300

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-13. Network configuration for Galileo launch and cruise, 1989.

DSS 14

70 m

DSS 12

34 m

DSS 15

34-m HEF

DSS 16

26 m

DSS 17

9 m

DSS 43

70 m

DSS 42

34-m STD

DSS 45

34-m HEF

DSS 46

26 m

TS, RS, RX

TS, RS, RX

TX, RX

TS, RS

TS, RS

TS, RS, RX

TS, RS, RX

TX, RX

TS, RS TS, RS

TX, RX

TS, RS, RX

TS, RS, RX

MIL 71

DTF 21

NOCC

OTHER POCCs

OTHER CENTERS

MGDS

DSS 66

26 m

DSS 65

34 m

DSS 61

34 m

DSS 63

70 m

EARTH ORBITER

LINK

COMM = GROUND COMMUNICATIONS

MIL 71 = MERRIT ISLAND LAUNCH AREA

(FLORIDA) POCC = PROJECT OPERATIONS CONTROL CENTER

NOCC = NETWORK OPERATIONS CONTROL CENTER

GSFC = GODDARD SPACE FLIGHT CENTER

DTF = DEVELOPMENT AND TEST FACILITY

TS = TRANSMIT S-BAND

RS = RECEIVE S-BAND

RX = RECEIVE X-BAND

TX = TRANSMIT X-BAND

NASCOM = NASA COMMUNICATIONS

EARTH ORBITER

LINK

CANBERRA

SPC 40

COMM

EARTH

ORBITER

LINK NASCOM

TO/FROM

GSFC

NASCOM

TO/FROM

GSFC

GOLDSTONE

SPC 10

COMM

JPL CCT

COMM

MADRID

SPC 60
Following the Challenger accident, the DSN suspended further effort on Galileo-relat

tasks except for technical support to the mission design team. The project desperate

searched for an alternate way of delivering the heavy Galileo spacecraft to Jupiter wit

out the high-energy Centaur launch vehicle. The search ended in August 1986 with th

discovery of the 1989 VEEGA trajectory, which was adopted as the new mission bas

line design.

While the new trajectory satisfied the limited injection capabilities of the IUS upp

stage, it carried with it several drawbacks of great significance to the DSN. One w

the flight time of six years; another was that the spacecraft would arrive at Jupiter 

maximum Earth-Jupiter range with a southerly declination of -23 degrees rather tha

minimum range with a northerly declination of +18 degrees, as would have been th

case for the 1986 launch. The maximum range translated into minimum downlink si

nal strength. In addition, the southerly declination meant that the most favorable locatio

for tracking Galileo at Jupiter would be the single site at Canberra, Australia, in th

southern hemisphere, rather than from two sites, Goldstone and Madrid, in Earth

northern hemisphere.

With a 1989 launch, an arrival in 1995, and a two-year orbital objective, it would 

1997 when the mission ended. The DSN was being asked to commit to a capabili

almost ten years in advance. This was an unprecedented degree of commitment f

NASA Headquarters to approve, considering that it had not been a simple matter 

get approval for even much shorter-term agreements.

Quite apart from that, by 1995, the spacecraft RTG power system would no longer 

adequate to run the spacecraft X-band transmitters at full power. They would have 

run at low power. This fact, combined with the adverse effect of increased range, mea

that the downlink signal power available to the DSN receivers would be about one-fif

of the original design value. This was nowhere near enough to capture the huge amou

of high-rate science data called for in the original mission design.

Having come this far with the mission, the designers were not inclined to reduce the

requirements, and there was no way to find a solution before launch, now less than tw

years away. It would be up to the DSN to find a solution to the problem, commit 

implementing it, and have it in full operational readiness when Galileo arrived at Jupit

on 7 December 1995.

The DSN plan to address this situation is illustrated in Figure 5-14 which shows the effe

of Galileo arrival at a southerly declination on the available downlink telemetry data rate

30

The Galileo Era: 1986–1996
As the figure shows, the Probe data relay of paramount scientific importance would ta

place in view of the southern hemisphere stations, where the view periods would be long

The fully arrayed 70-m and 34-m antennas at Goldstone and Canberra could suppo

the high-rate telemetry for all of this period. However, the less vital but still importa

Io encounter events would occur in the downlink telemetry “gap” between the settin

Madrid stations and the rising Goldstone stations. It was imperative that this gap 

filled or significantly reduced in order to capture the Io Encounter data.

In June 1987, a combined Galileo/DSN team of telecommunications engineers present

John Casani, then Galileo Project Manager, with a proposal for improving downlin

telemetry performance by 1 dB. The plan was to add a new convolutional decoder 

302

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-14. Galileo 1989 VEEGA mission: predicted X-band downlink performance Jupit

arrival, 7 December 1995. The horizontal scale in the figure shows the UTC time on 7 Decemb

1995, (this is also called Earth Received Time or ERT) at which the downlink telemetry data rat

shown in the upper vertical scale would be available at each of the Deep Space Communicati

Complexes. The lower vertical scale depicts the available downlink power margin relative to t

maximum data rate of 134 kilobits per second.

134

115

80

67

28

4

2

0

-2

-4

-6

Io ENCOUNTER PROBE DATA RELAY

JOI BURN

CANBERRA

GOLDSTONE

VLA

MADRID CANBERRA

TIME FROM Io CLOSEST

APPROACH (HOURS)

ERT (UTC) 7 DECEMBER 1995

134.4 KBPS TELEMETRY

MARGIN (DB)

HIGHEST AVAILABLE

DATA RATE (KBPS)

-12 -8 -4 0 4 8

8:00 12:00 16:00 20:00 24:00 4:00

ADVERSE PERFORMANCE, ARRAYED

STATIONS, 90% CONFIDENCE

CONVOLUTIONAL CODER

ENHANCEMENT (1 DB)

VLA ENHANCEMENT (3 DB)
type (15, 1/4) (see chapter 7 for an explanation of convolutional coding) to the exis

ing (7, 1/2) convolutional coder on the spacecraft Telemetry Modulation Unit (TMU)

A suitable switch would allow the TMU to be commanded to select either one. A

improvement of 1 dB in downlink telemetry performance would narrow the data g

during the Io Encounter as shown in Figure 5-4. The increase in science data retu

would be of great value to the Galileo project. However, because the decoders in th

DSN Mark IVA telemetry system were designed to handle the existing 7, 1/2 code, a

entirely new, very large decoder would be needed for the 15, 1/4 code. The DSN unde

took to develop such a machine and have it operational in the Network by 1995. Th

costs were estimated at about $1M for Galileo and about $3–4M for the DSN.18 

Furthermore, the DSN proposed that the downlink “gap” could be closed even furth

by combining the Galileo high-rate telemetry obtained by the DSN with a similar strea

of recorded data from the Very Large Array (VLA) antennas of the National Rad

Astronomy Observatory (NRAO) in Soccoro, New Mexico. Also, the VLA would pr

vide a valuable backup in the event that weather or a technical failure disabled th

Goldstone 70-m antenna at the critical time of Io Encounter. The possible addition 

the VLA to the Galileo Ground Data System had been under study for some time b

a special team led by James W. Layland, a telecommunications specialist in the TD

Planning Office. The team had identified a number of technical problems for whi

solutions were not available prior to launch.19

Encouraged by the successful demonstration of VLA support for the Voyager Neptun

Encounter, which would take place in August 1989, the DSN was confident that a sol

tion to the problems related to VLA support for Galileo data would be found befo

Galileo reached Jupiter, and planning proceeded on that basis.

Convinced by the arguments of the telecommunications engineers, Casani agreed to ad

the new convolutional coder to the spacecraft telemetry system. This was complet

shortly before launch, just in time for the DSN engineers to verify the decoding alg

rithms on which the design of the new DSN decoder would be based. This compl

device was to be developed by JPL’s Communications Systems Research Section, whe

the engineer responsible for the task, Joseph I. Statman, dubbed it the Big Viterbi Decod

(BVD). The goal was to deliver a demonstration model at Goldstone in May 1991, an

fully operational versions at Goldstone, Madrid, and Canberra by May 1995.

By November 1988, a DSN support plan for the 1989 mission had been approved b

NASA. Galileo would be supported by the 34-m standard antennas, the 34-m hig

30

The Galileo Era: 1986–1996
efficiency antennas and the 70-m antennas which had been upgraded from 64-m diam

ter in 1987–88.

In order to capture the high-rate (134 kilobits per second) telemetry data at maximu

Jupiter range, the DSN planned to use its full arraying capability of 70-m and 34-

antennas supplemented for critical Io Encounter period by the VLA. The VLA data w

to be recorded and delivered to JPL for non-real-time combining with the recordin

of the DSN arrayed data. 

The S-band uplinks would be provided by 400-kW transmitters at the 70-m antennas an

by 20-kW transmitters at the 34-m antennas. In addition, 20-kW X-band transmitte

were installed at each of the three 34-m HEF antennas and would be used to demo

strate the viability of X-band uplink technology in a critical operational environment.

For spacecraft navigation purposes, the DSN would generate the standard Mark IVA rad

metric data types, together with the necessary media calibration data. In addition, to me

the Galileo navigation requirement for angular measurement accuracy of 50 nanoradia

(1 sigma), the DSN Very Long Baseline Interferometry (VLBI) system would process th

special tones provided on the spacecraft S-band and X-band downlink radio carriers.

Radio science data generated by the Mark IVA Radio Science System during solar co

junctions and Jupiter occultations was to be supplemented with data for two oth

unique experiments.20 The Faraday Rotation Experiment required the DSN to reco

the right hand and left hand polarization signals at the output of the S-band orthomo

feed on the 70-m antennas. The data would later be used by the Radio Science tea

to determine the rotation of the plane of polarization (Faraday rotation) of the line

polarized S-band downlink as it passed through the magnetic field in Jupiter’s ion

sphere. Investigators would use this data to study the magnetic field of Jupiter at low

altitudes than was previously possible.

The objective of the other experiment was to detect the presence of gravitational wav

in the interplanetary medium. The success of this experiment was critically depende

on the sensitivity and stability of the two-way Doppler frequency measuring system

Two-way X-band Doppler was now available at the 34-m HEF antennas and the ne

essary frequency and phase stability had been designed into the microwave an

receiver-exciter subsystems for these antennas. Although the fractional frequency stab

ity of the X-band RF carrier signals remained to be verified after launch, expectatio

were high that the desired level, at least 5 parts in 1015 (5 x 10-15), would be achieve

304

Uplink-Downlink: A History of the Deep Space Networ
and that the hitherto undetected gravitational waves would be observed during the sol

oppositions in April 1994 and June 1995. 

NASCOM was to provide wideband digital communications circuits with a maximu

capacity of 224 kbps between all Complexes and the Mission Control and Computin

Center (MCCC) at JPL. This would be sufficient to transport the 134 kbps telemet

plus ancillary data in real time from the sites to JPL. To enable the German Spa

Operations Center (GSOC) to support Galileo cruise operations, provisions were al

made for low-rate data, voice, and teletype services from the GSOC at Weilheim, German

to the MCCC at JPL. 

In the weeks preceding launch, the scene at Cape Kennedy was colored by the activ

ties of a group of environmentalists protesting the use of radioisotope thermoelectr

generators (RTGs) as a prime power source for Galileo, despite the assurances of NAS

that the risk of endangering the environment or the population was minimal. NAS

asserted its confidence in the detailed risk analysis studies that had been made for th

and several earlier planetary spacecraft carrying similar RTG power sources, and th

launch went ahead as planned.

Because this was a combined STS/IUS launch, a high degree of coordination and tec

nical interfacing with other NASA Centers was involved. In the last few weeks befo

launch, the DSN participated in integrated simulation tests with the Kennedy Spa

Center (KSC), Johnson Space Center (JSC), and the Air Force Consolidated Space an

Test Center (CSTC). In these tests, state vectors were received from CSTC and process

by the DSN Navigation Team to produce predictions for eventual use by the init

acquisition station in making first contact with the spacecraft. Data was correctly tran

ferred across the various interfaces and delivered in a timely manner to the corre

destinations. Following a final “Operational Readiness Test,” the DSN was declared read

for launch on 17 September.

STS-34, carrying the Galileo spacecraft bound for Jupiter, was finally launched fro

Cape Kennedy on 18 October 1989. The launch was perfect and the subsequent deplo

ment of the IUS and Galileo spacecraft from the Shuttle cargo bay on the fifth Ear

revolution was completely normal. Following deployment, all the critical events leadin

to initial acquisition of the spacecraft downlink, first by the 26-m antenna at Goldston

and shortly after by the 34-m antenna at DSS 12, played out as exactly as planned. Th

success of the initial acquisition sequence testified to the excellence of the inter-Cent

coordination described above. Galileo was on its way to Jupiter via a close encount

with Venus in February 1990 and Earth flybys in December 1990 and December 199

30

The Galileo Era: 1986–1996
Over the next few weeks, as the Earth-to-spacecraft range continued to increase, th

downlink signal level reached the point where the 70-m antennas were needed to pr

vide the telemetry data required for spacecraft management and control. This creat

severe conflicts for other DSN users whose needs were, of necessity, of lesser priori

than those of Galileo. The situation was exacerbated in mid-December when the 70-

antenna at Madrid became immobilized due to a failed elevation bearing. The DS

responded immediately, and a team of JPL engineers arrived at DSS 63 two days lat

to start repair work. Under intense pressure because of the rapidly approaching Ven

encounter, and working under extremely difficult winter conditions, the team was ab

to replace the massive bearing and return the antenna to operations on 25 January, f

teen days before Venus Encounter.

The Galileo closest approach to Venus occurred on 9 February 1990, during the mut

al view of DSS 43 and DSS 63. Playback of the first images of Venus began over DS

14 on 13 February. Three hours into the Galileo pass, the Goldstone antenna had to 

shut down because of exceptionally high winds at Goldstone. Despite the resulting lo

of data, reports from the Galileo science team commented favorably on the high qua

ty of the downlink data delivered by the DSN. The Galileo Navigation Team used th

Doppler and ranging data generated by the DSN to confirm that the gravity assist fro

the flyby resulted in the expected equivalent velocity increase of 2.2 km per second.

Within a few days of Venus Encounter, the sustainable downlink telemetry data rate o

even the 70-m antennas had fallen to 40 bps, and by March it had fallen still furth

to 10 bps. This was due to an unfavorable pointing angle of the spacecraft low-ga

antennas used for transmitting the downlink signal to the DSN. During the first ye

of its orbit, the spacecraft was oriented with the spin axis pointed towards the Sun. 

this attitude, the Sun shields would protect the spacecraft and the furled X-band hig

gain antenna from damaging solar thermal radiation, and the spacecraft would depen

on its low-gain antennas for uplink and downlink. When the spacecraft orbit pass

beyond the Earth orbit (1 AU), solar heating would no longer be a problem. The spac

craft would be oriented toward Earth, the big high-gain antenna would be deployed an

the X-band uplink and downlinks could be used. Until then (April 1991), the S-ban

low-gain antennas would have to suffice.

Following repair of the DSS 63 elevation bearing, it was decided to inspect and car

out a bearing maintenance program on all three 70-m antennas to assure their integ

ty for the rest of the Galileo mission. This work, which required three weeks of downtim

at each antenna, was started in May 1990 and completed successfully at DSS 43 

306

Uplink-Downlink: A History of the Deep Space Networ
January 1991. Fortunately, during most of this time, the spacecraft was approaching th

first Earth flyby and the need for 70-m support was considerably reduced.

As the spacecraft began to approach Earth in August, the DSN intensified its effort 

deliver high-quality Delta Differential One-way Ranging (DDOR) for use by the spac

craft navigation team in refining the spacecraft targeting parameters for the first Ear

Encounter.

The 26-m and 34-m stations at Canberra, Madrid, and Goldstone supported th

operationally intense four-hour period of Earth-1 Encounter activity of 8 Decemb

1990 without incident. During this period, very high downlink signal levels we

able to sustain telemetry data rates of 134 kilobits per second to provide the pro

ect with 100 percent of the desired science data. Closest approach to Earth occurre

at an altitude of 960 kilometers over the Caribbean Sea and out of view of the DSN

between Madrid set and Goldstone rise. The effort expended by the DSN on th

DDOR campaign prior to Encounter was well justified when the Galileo Navigatio

Team estimated that the improved targeting errors resulting from the use of th

DDOR data translated into a spacecraft fuel savings of approximately 6 kilogram

an important factor for consideration in the eventual design of the Jupiter satelli

tour, still five years in the future.

The geometry of the first Earth flyby is shown in Figure 5-15. A dramatic picture 

Antarctica taken by the Galileo spacecraft camera several hours after the Earth flyby 

a distance of 200,000 km (124,000 miles), is seen in Figure 5-16. The downlink da

from which this picture was constructed was received at the Goldstone 34-m antenn

DSS 12 at 134 kbps a few hours after closest approach on 8 December 1990.

In the immediate post-Encounter period, the project took advantage of the prevailin

downlink performance to return all of the Earth Encounter science data at high da

rates. However, as the Earth spacecraft range increased, the downlink performance ma

gins rapidly decreased, and by the end of January 1991, the telemetry data rate w

back to about 40 bps. By then, all three 70-m antennas were available due to compl

tion of elevation bearing work. 

One of the final events in the Venus to Earth-1 portion of the Galileo mission w

to be the unfurling of the high-gain antenna (HGA) in April 1991. At that tim

the danger of solar heating was past and the spacecraft could be safely oriented towar

Earth to point the big HGA directly at the DSN antennas. The X-band uplink an

downlink would become the prime telecommunication channels. The command 

30

The Galileo Era: 1986–1996
unfurl the HGA had already been transmitted to the spacecraft and verified for com

pleteness. It lay resident in the spacecraft computers waiting for the correct time 

execute, and that time had finally arrived. A new phase of the Galileo mission w

about to begin.

However, when the command to unfurl the HGA was activated, the redundant deplo

ment motors ran for eight minutes before automatically switching off. A normal deployme

should have taken three minutes. Several hundred trials had been successfully comple

ed beforehand, but the spacecraft spin changed by less than was expected with a fu

deployment, and the Sun sensors indicated some partial obscurement. Something w

drastically wrong with the HGA.

The rest of the spacecraft appeared to be completely normal, and the mission conti

ued on S-band while the HGA “anomaly” was investigated. The conclusion was th

three of the eighteen ribs in the HGA structure had remained stuck in the stowed 

furled position, and the “anomaly” now became the “problem” of how to recover th

HGA. It took the HGA Recovery Team two years to solve this problem as they su

jected the antenna structure to repeated heating and cooling cycles and “hammerin

shocks from the antenna drive motors. 

308

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-15. Geometry of the Galileo first Earth flyby.
Galileo requirements for DSN operations coverage of the lengthy heating and coolin

cycles were greatly increased, and conflict resolution for DSN antenna time became 

major effort. The immediate impact of the HGA problem on DSN implementatio

plans was loss of the Big Viterbi Decoder demonstration, planned for May and Jun

when the X-band downlink should have been available. The X-band uplink demo

stration at DSS 15 during the solar opposition in March as part of the Gravitation

Wave Experiment was also a casualty.

Meanwhile, the spacecraft continued outward bound towards the apoapsis of its tw

year orbit around the Sun (see Figure 5-10). On the fringe of the asteroid belt 

October 1991, it would make a close pass by the Asteroid Gaspra before returnin

to Earth for its final gravity-assist flyby in December 1992. By mid-1991, Optic

Navigation (OPNAV) data, because of its potential for extreme angular precisio

had become a key data type for the Galileo Navigation Team. In this scheme, th

target image, the asteroid Gaspra, is photographed against a known star backgroun

from which the precise angular position of the target can be determined. Using th

DDOR data to determine the spacecraft position enables the spacecraft to be ta

geted very precisely to the desired position for a close flyby. Because the downlin

30

The Galileo Era: 1986–1996

Figure 5-16. Galileo image of Earth: Antarctica. 
performance was now in the 10 bps to 40 bps range, it was not possible to recov

the images in real time. The strategy that was employed involved recording the imag

on the spacecraft tape recorder and then transmitting the playback data to the DS

at whatever data rate the downlink could sustain. Recovery of the necessary imag

was, therefore, very time-consuming for 70-m antennas. The DSN expended near

400 hours of 70-m antenna time in recovering the OPNAV data for the Gasp

Encounter alone.

Closest approach to Gaspra occurred on 29 October 1991 as the spacecraft passe

within 1,600 km of the asteroid, a very precise maneuver indeed, and an impre

sive demonstration of the power of OPNAV. Playback of all the Gaspra science 

10-40 bps occupied many months following the actual encounter and was not com

pleted until November of the following year, 1992, just prior to the second Ear

Encounter.

The second Earth Encounter took place on 8 December 1992, with near-perfect ta

geting results. The altitude at closest approach was only 303 km on this occasion an

occurred over the south Atlantic Ocean, again out of view of any DSN tracking st

tion. Because the gap in DSN coverage would be about two hours in duration, a

elaborate arrangement of smaller antennas in Santiago, Chile; Perth, Australia; and Okinaw

Japan, was set up to cover the gap. They would accomplish this by recording the dow

link Doppler signal and returning it to JPL via the NASA Tracking and Data Rel

Satellite System (TDRSS). The purpose of this effort was to search for the occurrenc

at closest approach, of an orbit anomaly, possibly associated with fundamental gravit

tional or general relativity theory. Although high-quality data was provided from all 

the sites, no orbit anomaly was found.

The targeting precision for the second Earth flyby was near-perfect. Galileo passed wit

in one kilometer of its intended path, one-tenth of a second ahead of its predicted tim

This, the last of the three gravity assists, added 3.7 km per second to the spacecraf

speed in its solar orbit. Galileo was finally on an elliptical path to intersect the orbit 

Jupiter, 780 million km from the Sun, on 7 December 1995. As the spacecraft depar

ed the environs of Earth on 16 December 1992, it captured the unique picture of Ear

and the Moon shown in Figure 5-17. 

Except for the HGA problem, and that was a very big exception, the success of th

Galileo mission to this point had been extraordinary. But the primary mission cou

not begin until the spacecraft reached Jupiter, and that lay three years ahead. Wi

the downlink getting weaker every day, and no sign of progress in recovering th

310

Uplink-Downlink: A History of the Deep Space Networ
HGA, the question of what could be done to save the mission was receiving a gre

deal of attention. Because of the long lead time involved in implementing new cap

bility in the DSN, it was now necessary to make a decision as to whether to acce

the loss of the HGA as inevitable and redesign the mission for S-band only, or 

continue with the original X-band design in the hope that the HGA would event

ally be recovered.

In announcing his decision in February 1993, Galileo Project Manager William J. O’Ne

declared: 

31

The Galileo Era: 1986–1996

Figure 5-17. Earth and Moon from Galileo, December 1992. 
We are now proceeding to implement the Galileo mission using the LGA

(S-band). We are absolutely confident of achieving at least 70 percent of

our primary objectives including 100 percent of the Probe mission and several thousand of the highest resolution images of Jupiter ever planned. All

the instruments will make their most important observations, and we will

monitor the Jupiter magnetosphere virtually continuously, albeit at low data

rate. The success of Galileo without the HGA at Jupiter will be a technological triumph. Developing the extensive, new spacecraft flight software and

ground software and hardware, including state[-]of[-]the[-]art enhancements

in the Deep Space Network, is a big challenge to complete in just three

years. The project and the DSN are fully up to this challenge. Galileo will

indeed fulfill its promise and be a magnificent mission at Jupiter.21

The new course was set, and the DSN moved forward upon it.

While attempts to free the antenna were in progress, Galileo and DSN engineers explor

the possibility of continuing the mission using only the existing S-band capability an

the low-gain antennas (LGAs) on the spacecraft. Earlier studies had shown that improv

ments in the coding and efficiency of the telemetry downlink, combined with a substant

enhancement in DSN receiving capability at S-band and suitable data processing at JP

could indeed produce a viable S-band mission.22 It was estimated that as much as 7

percent of the original mission objectives could be achieved. 

The DSN began design and development work almost immediately, and by Februa

1993, when the decision to commit the Galileo mission to S-band was made, the DS

had already made substantial progress toward meeting the new requirements. The DS

continued to support the ongoing mission at low data rates consistent with the existin

S-band capability, while moving toward the new configuration that would be requir

for orbital operations in December 1995, as the new hardware and software for the ne

DSCC Galileo Telemetry (DGT) subsystem became available.23 The development of th

DGT is discussed later in this chapter.

Two key elements in the design of the S-band mission were related to new spacecra

flight software. These would be transmitted to the spacecraft to reprogram its compu

ers in two phases. The Phase 1 set of flight software would compensate for the fact tha

without the HGA, the all-important Probe entry data could not be returned to Ear

in real time. It would have to be recorded on the spacecraft tape recorder for later pla

back at the low data rates now determined by the LGA mission design. The spacecraf

redundant command and data system memory would be used to provide data stora

312

Uplink-Downlink: A History of the Deep Space Networ
backup for the tape recorder in case the critical Probe data got “lost” during its deli

ery to the project.

Once that data was safely received by the DSN, the Phase 2 flight software could 

sent to the spacecraft for reprogramming its onboard computers. The Phase 2 softwa

would provide programs to condense the huge amount of science data collected by th

Orbiter during its two-year orbital mission, without losing any of the scientifically impo

tant information. That data could then be transmitted to Earth at a data rate consiste

with the capabilities of the S-band downlink.

Without these enhancements, the data transmission rate via the LGA at Jupiter wou

be limited to 8–16 bps. When coupled with the DGT and the fully arrayed config

ration of the DSCCs, including the Parkes Radio Astronomy antenna at Canberra, th

data rate could be increased by as much as a factor of 10, up to 160 bps.

Although the original X-band HGA mission design had been based on a downlink da

rate of 134,000 bps, most of the science investigations had been adapted to the low

data rates, and, with the exception of the Jupiter atmospheric circulation observation

few of the science experiments planned for the original mission had to be abandone

Through most of 1993, the Galileo S-band downlink was able to sustain a telemet

data rate of 40 bps on the 70-m antennas, but as the Earth-to-spacecraft range conti

ued to increase, the data rate fell to 10 bps by the end of the year. The most notab

event in 1993 was the close flyby of another asteroid named Ida. Because the optic

images being used by the Navigation Team to target the asteroid required 30 hours 

70-m antenna time to retrieve at the low data rate, few images were provided. Neverthele

they were sufficient to satisfy the targeting specifications, and good imaging of the aste

oid was obtained during the August 1993 encounter sequence. Only five of the I

images could be played back in 1993. The remainder were played back over a perio

of four months in the following year when the data rate returned to 40 bps. One 

the images contained the interesting view of Ida with its own tiny satellite, shown 

Figure 5-18. The image was taken 14 minutes before closest approach on 28 Augu

1993, at a range of 10,870 km. 

In general, the Galileo mission moved through 1994 in the cruise mode with preva

ing downlink conditions similar to those of the previous year. In July, the Galileo spacecra

was in a unique position to observe the Shoemaker-Levy Comet impacts on Jupiter. Fi

of the eleven science instruments onboard the spacecraft were able to make observation

31

The Galileo Era: 1986–1996
which were stored on the spacecraft tape recorder for later playback at 10 bps as th

necessary antenna time became available during the rest of the year. 

Toward the end of 1994, the first prototype models of several of the components of th

DGT became available for engineering demonstration tests with live spacecraft data

The new Block V Receiver (BVR) was used in downlink acquisition and tracking tes

with a live signal from the spacecraft. This was a special software-based receiver design

to track the suppressed carrier downlink the spacecraft would transmit when it activa

ed the Phase 2 flight software, in the orbital operations phase, in March 1996. Performan

tests of the Full Spectrum Recorder (FSR) showed excellent agreement with theoretic

predictions for signal-to-noise-ratio, harmonic contribution, and tracking loop capabi

ty. Galileo data that had been acquired simultaneously at DSS 14 and DSS 15 an

recorded earlier in the year were successfully combined using a prototype of the Fu

Spectrum Combiner (FSC). The mean combining gain achieved with the experiment

data was within 0.02 dB of the gain expected from perfect combining. Later demo

strations of intercontinental combining, using Galileo data from DSS 43 and DSS 1

gave equally impressive results.

314

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-18. Asteroid Ida and its moon.
Verification of the operational performance of the DGT continued in 1995 as the insta

lations progressed at each of the DSCCs. By September 1995, the BVR had been ful

implemented and demonstrated at all 70-m stations, and the Galileo spacecraft was switch

to the suppressed carrier downlink mode of operation that, together with the BVR 

the 70-m stations, would be standard for the rest of the mission.

The Galileo S-band downlink was able to sustain a data rate of 8 to 16 bps throug

out 1995, as the most critical events of the entire mission approached. As a precautio

against the occurrence of problems with the 70-m antennas during these periods, ea

of the antennas was taken out of service for a few weeks for hydrostatic bearing an

subreflector maintenance. DSN and Galileo mission operations personnel rehearsed th

time-critical sequences and verified the data flow paths and configurations. In Februar

the new Phase 1 flight software had been uplinked to the spacecraft. The long com

mand sequences were received correctly by the spacecraft, were loaded into the compute

and began operating in March. All was ready as the time for Probe release approache

The Probe release sequence began on 5 July 1995. After a system status check, the Pro

transferred to its own internal power supply and the “umbilical” cable connecting Pro

to Orbiter was disconnected. The spacecraft turned to the correct attitude for pointin

the Probe towards Jupiter, and, in response to a “GO” command, the Probe was releas

at 10:07 p.m. PDT, 12 July, to travel the rest of the way on its own. Nothing mo

would be heard from the Probe until it established its uplink relay to the Orbiter as 

descended through the Jupiter atmosphere. That would be the last 60 minutes of its lif

Three weeks later, the Orbiter executed a deflection maneuver to change its trajecto

slightly so that it would not enter the Jupiter atmosphere on arrival, but would arri

at the correct point for Jupiter Orbit Insertion (JOI).

Both the Orbiter and the Probe arrived at Jupiter during the overlapping view perio

of DSS 43 and DSS 14 on 7 December 1995. In the final hours of its approach 

Jupiter, the Orbiter was able to capture some images of distant Io as it crossed the orb

of the satellite. Limited by the capabilities of the S-band mission, the Io images were 

far cry from the finely detailed pictures that the original mission design would have pr

duced. Nevertheless, they were adequate to show the changes that had taken place sin

the Voyager flyby 17 years before. 

The Orbiter made its closest approach to Jupiter at 2:46 p.m. PST, and the Pro

started transmitting its science data to the Orbiter thirteen minutes later. Althoug

the Probe data was not being sent to Earth in real time, telemetry from the Orbit

31

The Galileo Era: 1986–1996
verified that the L-band signal from the Probe was being received and recorded b

the Orbiter, much to the relief of everybody concerned. By 4:14 p.m., recording 

the Probe data was complete and the spacecraft was prepared for the next major even

insertion into Jupiter orbit. This was accomplished with great precision by the 40

Newton retropropulsion engine, built by Messerschmicht-Bolkow-Blohm (MBB) an

provided by Germany as a partner in the Galileo project. The first orbit of Jupit

began. Preliminary indications were that 57 minutes of Probe data had been receiv

and recorded by the Orbiter prior to loss of Probe signal—a most remarkable feat 

mission design and spacecraft technology. Actual tape playback of the Probe scien

data would begin at the end of January 1996 and was expected to take about tw

months to complete at 10 to 16 bps. The Phase 1 software had proved its worth.

From the DSN perspective, support for all the events of the critical Probe entry and JO

sequence had been very nominal. The BVR receivers had continued to track the dow

link signal throughout the retroengine burn, and all desired telemetry and radio metr

data products had been delivered. There were no anomalies or problems to be reporte

In each of the three years after Galileo entered its final Earth to Jupiter cruise phase 

1992, the DSN had supported a major scientific event, two asteroid encounters and th

Comet Shoemaker-Levy observations. A solar conjunction and a solar opposition h

provided good data for radio science observations. Gravitational wave observations, 

conjunction with Ulysses, had also been supported. An emergency control center f

Galileo had been established at Goldstone and could have supported all operations h

the Mission Control Center at JPL been unavailable for any reason.

Many resource scheduling problems that appeared intractable early in 1993 were eve

tually resolved by DSN scheduling to fully meet Galileo requirements for 70-m trackin

time in each of the three years. The 34-m Network was used only for test purposes du

ing this time. The BVR had reached maturity and was now a standard operation

component of the almost-completed DGT. Over the period of January 1993 to Decemb

1995, the DSN maintained an average downlink telemetry data capture rate of 98

percent. In the same time, it correctly transmitted over 220,000 uplink commands 

the Galileo spacecraft.

With the completion of the Probe and JOI events just described, the mission entered th

final phase: the orbital operations phase. During the next two years, the spacecraft wou

make several close encounters with three of the Jupiter satellites, using the gravity ass

technique to move from one orbit to another in sequence. The first encounter would 

316

Uplink-Downlink: A History of the Deep Space Networ
with Ganymede in June 1996, following an adjustment of the spacecraft orbit to avo

repeated exposure to the Jupiter radiation environment at each periapsis passage. 

By the beginning of 1996, all the components of a single-antenna version of the DG

were onsite and being tested.25 After a successful Ground Data System operations demo

stration in May, using simulated Phase 2 flight software, this version was put online f

live Galileo support. A short time later, inflight loading of the real Phase 2 softwa

began. It took over sixty-five continuous hours to transmit the program to the spac

craft, the longest command sequence ever transmitted by the DSN Command System

There were no transmission errors. After verifying that both computers on the spac

craft had been correctly loaded and the data properly processed by the ground da

system, the spacecraft was commanded into the new mode of operation. It immediat

ly began transmitting the new downlink packetized telemetry at 32 bits per second f

processing by the new DGT at the DSN stations. 

The DGT single-antenna version was used to support the first Ganymede Encounter 

June 1996. At this phase of the mission, the single-antenna DGT, in conjunction wi

the new downlink telemetry format, could support 40 bits per second over DSS 14 an

DSS 63, and 80 bits per second over DSS 43, already a substantial improvement ov

the former performance of the downlink. The science data could be played back in da

rather than weeks, enabling the first Ganymede data to be presented at a press confe

ence on 10 July, just two weeks after closest approach.

A second Ganymede Encounter in September was supported by the single-antenn

DGT configuration in a similar way, with equally satisfactory results. In September an

October, the DSN had been engaged in end-to-end ground data system testing of th

DGT in its full operational arraying mode. At SPC 40 in Canberra, the Galileo dow

link was processed through the multiple-antenna version of the DGT, with signals fro

DSS 14 in Goldstone being combined, in real time, with signals from DSS 43, DS

42 at Canberra, and DSS 49 at Parkes. After processing at SPC 40, the resultin

enhanced telemetry stream was sent to JPL via the GCF for delivery to the projec

During the tests, the spacecraft was run at all data rates up to 160 bps, the highest b

rate available. These rates required full arraying capability to recover the data but we

demonstrated successfully. The demonstrations revealed a number of configuration an

procedural problems that were rapidly corrected. There were no anomalies related 

the design of the DGT.

Now confident in its capability to support encounter operations in the fully array

mode, the DSN used the DGT for the Callisto Encounter in November with very sa

31

The Galileo Era: 1986–1996
isfactory results. Although the introduction of arrayed operations into the Galileo dow

link sequences resulted in increased operational complexity, it provided almost tenfo

increase in the downlink data rate that would otherwise have been possible. 

Based on the operational performance of the DGT in supporting the Callisto Encount

and on confidence in the DSN ability to deal with the increased operational comple

ity of fully arrayed operations, the Project Manager elected to schedule every Galil

pass from then to the end of the mission in that mode. A functional block diagram 

the DSN in the full array configuration is shown in Figure 5-19.

The Europa Encounter in December 1996 and the six remaining satellite encounters 

the Galileo prime mission in 1997 were all conducted in the array mode. As it work

through these events, DSN experience in handling the complex operational process

involved in real-time arraying, rapidly improved to the point where intercontinental ope

ations became routine. The DSN had reached a new level of competence in a ve

complex operational environment. A typical data rate profile for the Galileo downlin

in 1997 routine array operations is shown in Figure 5-20.

318

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-19. The DSN in full array configuration for Galileo Jupiter orbital operations. 
As it moved towards the conclusion of the Prime Mission in 1997, Galileo provid

its sponsors with a cornucopia of imaging and other scientific riches. Typical of th

imaging results is the striking photo of the surface of Europa shown in Figure 5-2

This image was recorded by the spacecraft during the Europa Encounter on 20 Februa

1997. It was downlinked as part of the total Europa science data playback sequen

at 40 to 80 bps during subsequent DSN array passes over the following five weeks

The quality of this image and the many others like it that followed is a tribute to th

innovative ideas of the DSN and to the Galileo engineers who were involved in th

effort to recover a viable downlink for the mission after the loss of one of its key el

ments, the HGA.

Background for Ulysses

In 1977, NASA and ESA agreed upon a joint mission to study the surface of the Su

and other solar phenomena. It would be called the International Solar Polar Missio

(ISPM) and would comprise two spacecraft travelling on separate trajectories passing ov

31

The Galileo Era: 1986–1996

Figure 5-20. Full DSN array operations for Galileo: typical downlink data rate profile.
opposite poles of the Sun. One spacecraft would be built by ESA, the other by NASA

who in addition would provide the launch vehicle. Both spacecraft would carry a com

plement of experiments drawn from science communities in the United States and Europ

ISPM was a natural successor to the Helios mission of a decade earlier. Helios h

explored the solar environment from an equatorial orbit around the Sun. ISPM was 

make similar observations from a polar orbit over the Sun. To create an orbit passin

over the poles of the Sun, however, was much more difficult than creating an orbit lyin

entirely in the plane of the ecliptic. To accomplish this, mission designers planned 

make use of a high-velocity gravity assist from Jupiter to change the plane and dire

tion of the spacecraft trajectory to the extent necessary to achieve the desired north an

south polar passages.

The solar polar trajectory that was eventually initiated by the single spacecraft laun

of 1990 is shown in Figure 5-22. In the original plan, there were to have been tw

spacecraft orbiting the Sun in opposite directions.

320

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-21. Galileo image of icebergs on the surface of Europa.
In keeping with the NASA policy at the time of the original agreement, ISPM wou

use the Space Shuttle as the primary launch vehicle. A single launch was planned f

1983. The two spacecraft would be mounted in tandem on a single injection vehic

After burnout and separation from the upper stage, each spacecraft would be inject

into its individual trajectory towards Jupiter.

In 1980, because of NASA difficulties with development of the Space Shuttle, the laun

was delayed to 1985. A year later, due to NASA problems with funding, the NAS

spacecraft was canceled, and the launch of the remaining ESA spacecraft was furth

delayed to 1986. At the time, the circumstances surrounding the launch delays and ca

cellation of the NASA spacecraft raised a storm of protest at ESA, the aftermath 

which persisted for many years in the European science community. Eventually, the ES

spacecraft was completed and placed in storage, and the ISPM mission was approp

ately renamed Ulysses, after the legendary Greek hero who, after his return from th

Trojan wars, set out to explore “the uninhabited world beyond the Sun.”

32

The Galileo Era: 1986–1996

Figure 5-22. Ulysses solar polar trajectory. 
In 1987, in the aftermath of Challenger, NASA and ESA jointly agreed that Ulysses wou

be launched in October 1990, following the Magellan and Galileo launches in 1989.26

The Ulysses spacecraft had a mass of 370 kg and was radiation-resistant and spin-stab

lized. The flight configuration is shown in Figure 5-23. Prominent features included th

1.65-m high-gain antenna (HGA), the Radio Isotope Thermoelectric Generator (RTG

and the 5.5-m radial boom, which provided an electromagnetically clean environme

for certain experiments. A 72-m dipole wire boom and a 7.5-m axial boom served 

antennas for the Unified Radio and Plasma-wave experiment.

The main platform of aluminum honeycomb provided a mounting surface for all th

electronic units and for the Reaction Control Equipment and its hydrazine fuel tan

Science instruments other than those mounted on the radial boom were also mount

in the body of the spacecraft. 

The spacecraft carried redundant transponders, each of which included S-band receive

and 5-watt transmitters, and redundant 20-watt X-band transmitters. Located on th

322

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-23. The Ulysses spacecraft inflight configuration. 

HIGH GAIN ANTENNA

RADIOISOTOPE

THERMOELECTRIC

GENERATOR

REACTION CONTROL

EQUIPMENT (RCE) TANK

RCE THRUSTER CLUSTER

AXIAL BOOM

WIRE

BOOM

DRIVE

WIRE BOOM

COSMIC RAYS/SOLAR

PARTICLES

LOW ENERGY

IONS AND

ELECTRONS

SOLAR X-RAY/COSMIC

GAMMA BURST

MAGNETIC

FIELDS

UNIFIED RADIO

AND PLASMA

WAVES

RADIAL

BOOM

COSMIC

RAYS/SOLAR

PARTICLES

SOLAR WIND-ION

COMPOSITION

HIDDEN IN THIS CONFIGURATION VIEW:

ENERGETIC PARTICLE COMPOSITION

AND INTERSTELLA GAS COSMIC DUST
spin axis of the spacecraft, the HGA permanently pointed toward Earth to provide 

band uplink and downlink and X-band downlink communications with the DSN. Tw

low-gain antennas (LGAs) provided hemispherical coverage in the forward- and rea

ward-looking directions for S-band only, and omnidirectional uplink and downlin

communications when the spacecraft was in the early phases of the mission.

Two fully redundant tape recorders supplemented the telemetry system to ensure co

tinuous collection of scientific data throughout the mission. When contact with the DS

was not available, data was recorded on the spacecraft for later playback when DSN co

erage became available. A variety of selectable downlink data rates between 128 bits p

second and 1,024 bits per second were provided for recorded or real-time data.26, 27

The Ulysses spacecraft carried nine scientific experiments, all related to the investigatio

of a wide range of fields and particles phenomena of the Sun and its environment. 

addition, two radio science experiments making use of the spacecraft and DSN uplin

and downlinks were to be carried out. The solar corona experiment would study th

density, velocity, and turbulence spectrum of the coronal plasma near the Sun. Th

Gravitational Wave Experiment (GWE) would search for low-frequency gravitation

waves. The GWE experiments would be correlated with similar observations made b

Galileo in order to confirm the detection, and determine the directional characteristic

of any gravitational wave that might be detected.

Ulysses’s requirements on the DSN for tracking and data acquisition support were com

paratively modest in comparison to those of Galileo and other JPL flight projects.28 Th

Mark IVA 70-m antenna upgrades and the two 34-m subnets had been completed b

the time of the Ulysses launch, so the DSN was able to meet most of Ulysses’s requir

ments with one 34-m subnet while Galileo and Magellan (in extended mission statu

were accommodated on the 70-m and remaining 34-m antennas. For a few weeks du

ing solar conjunctions and oppositions, radio science experiments, including the Gravi

Wave Experiment, were conducted on the 70-m antennas at the rate of one or two pas

es a day.

The DSN configuration for Ulysses support was similar to that shown for Galileo 

Figure 5-13. Within the SPCs, the Mark IVA telemetry, tracking, command, radio sc

ence, and monitor and control systems were fully capable of handling all the Ulyss

uplink and downlink requirements. Telemetry data and S-and X-band radio metric da

were delivered to the project at JPL via the Mark IVA GCF. Navigation requiremen

for VLBI data were handled by the NOCC Navigation Subsystem. There were no requir

ments for arraying. 

32

The Galileo Era: 1986–1996
Ulysses Solar Mission

Placed into a 300-kilometer Earth orbit by a perfect Space Shuttle launch on 6 Octob

1990, Ulysses was powered into a trajectory towards Jupiter by a combined Interim Upp

Stage (IUS)/Payload Assist Module (PAM) injection vehicle. About 30 minutes after th

PAM burnout, the spacecraft S-band downlink was acquired by the 26-m and 34-

antennas at Canberra, and the Earth-Jupiter phase of the Ulysses mission began. Th

first of several large trajectory correction maneuvers (TCMs) to target the spacecraft 

the Jupiter aim point was carried out over a four-day period in mid-October. 

In early November, shortly after deployment of the Axial Boom, the spacecraft X-ban

antenna beam unexpectedly developed an oscillatory motion called nutation. Althoug

the resulting variations in downlink signal threatened future use of the X-band dow

link, the nutation effect gradually disappeared as the Axial Boom became shadowed fro

solar thermal effects by the spacecraft, whose attitude slowly changed to keep the HG

pointed toward Earth. Radio science observations made during the first solar oppositio

in December 1990 showed no deleterious effects from HGA nutation. A small TCM

carried out in July 1991 brought the trajectory within 250 kilometers of the desir

Jupiter aim point. 

Moving very rapidly along the corrected trajectory, and with uplink and downlink ope

ating normally, Ulysses reached the Jupiter aim point on 8 February 1992. DSN rad

metric data confirmed that the closest approach to Jupiter was 6.31 Jupiter radii (R

as expected. Note: The Galileo spacecraft made its closest approach to Jupiter at 4.0 

in 1995 with special protection to withstand the Jupiter radiation environment.

Ulysses began moving in a new orbital plane, and, for the first time, a planetary spac

craft was travelling out of the plane of the ecliptic. The trajectory took it on a big loo

back toward the Sun, passing under the south polar region of the Sun, back across th

equator, and over the north polar region. It was these two regions, around 80 degre

south and north latitude, that would be of greatest scientific interest.

Throughout 1992 and 1993, all spacecraft, science, and routine antenna pointing ope

ations were performed without incident. DSN support on the 34-m antennas was routin

with 70-m passes being scheduled for special events.

On 26 June 1994, at 70 degrees south latitude, the spacecraft entered what scientis

consider to be the south polar region of the Sun. For the next four months, the spac

craft collected science data on the complex forces at work in that region. Whe

324

Uplink-Downlink: A History of the Deep Space Networ
possible, DSN schedules were adjusted to accommodate the demand for increas

tracking time.

In August, the spacecraft moved into the Sun-Earth region, where the spacecraft’s Ax

Boom was again illuminated by the Sun. It was known from earlier experiences durin

the mission that this illumination would cause uneven heating of the Axial Boom, whic

in turn, caused a slight wobble in the attitude of the spacecraft. The wobble was co

trolled by an onboard control system that maneuvered the spacecraft to keep the HG

pointed to Earth. Ground controllers in constant contact with the spacecraft carried o

this technique and allowed the onboard system to detect and correct unwanted motio

The European Space Agency’s tracking facility at Kourou, French Guiana, was modifi

and brought online to help the DSN antennas in Canberra provide 24-hour covera

of the spacecraft for this purpose.

The spacecraft reached its most extreme latitude of 80.2 degrees south in mid-Septemb

and Ulysses mission scientists began reporting important discoveries in the structure an

composition of the Sun’s solar wind and magnetic field at a science conference in Noordwij

Netherlands. 

In February 1995, as the spacecraft approached a position in back of the Sun as view

from Earth (opposition), the spacecraft S-band transmitter was turned on to compl

ment the X-band transmitter in conducting the solar corona radio science experimen

During the “opposition period,” the DSN Radio Science System would record chang

to the S-band and X-band spectra induced by passage through the solar corona. Th

Ulysses Radio Science Team would use these data to measure the electron content 

the Sun’s corona.

Ulysses recrossed the Sun’s equator (ecliptic) at a distance of 1.3 AU on 12 March 199

With all systems in good operating condition, it headed toward the north polar regio

When it reached 70 degrees north latitude on 19 June 1995, the second and final pha

of the primary mission began. Over the Sun’s north polar region, Ulysses continued 

observe such solar phenomena as the speed of the solar wind, the rate of loss of mat

rial from the Sun, the outward pressure of the solar wind, its impact on the shape 

the heliosphere and coronal structure, and the entrance or repulsion of high-energy co

mic rays at these high latitudes. This period of high science activity was supported b

the Canberra, Madrid, and Goldstone stations at a rate of 16 hours per day. The obse

vations continued through September, until the spacecraft left the high-latitude regio

of the north solar pole. 

32

The Galileo Era: 1986–1996
On 29 September 1995, five years after it began, the end of the Ulysses primary m

sion was reached. Ulysses then began the long journey back out to the orbit of Jupit

making fields and particles observations as it progressed. On reaching the giant plane

distance of 5.4 AU on 17 April 1998, the spacecraft would once again head back on 

second high-latitude trajectory to reach the vicinity of the Sun in September 2000. 

diagram of the second Ulysses polar orbit of the Sun is shown in Figure 5-24. 

The DSN continued to provide 34-m antenna support for the “routine phase” of th

Ulysses extended mission, at a level of about 10 hours per day through 1996 and 199

With the spacecraft in good condition and sustaining requirements minimal, the DS

expected to support Ulysses through a second solar passage in the years 2000 and 200

Background for Mars Observer

Mars Observer was to be the next step in NASA’s long involvement with exploration 

the Red Planet, which had begun thirty years before with the Mariner 4 spacecraft an

the first crude pictures of the planet’s cratered surface. The last spacecraft to visit Ma

326

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-24. Ulysses second polar orbit.
had been the twin Viking Orbiters and Landers in 1976, on a mission to search f

signs of life from the distant past. The primary objectives of the Mars Observer missio

were to identify and map the chemical and mineral composition of the surface, mea

ure the topography of the surface landforms, define the gravitational field, and sear

for a planetary magnetic field. It was also intended to study the carbon dioxide, wat

and dust in the Martian atmosphere. The mission was to last approximately one Ma

year, equivalent to about two Earth years. The spacecraft carried seven science instr

ments designed to accomplish these objectives. 

Mars Observer also carried a radio-receiver package provided by the French space agenc

Centre National d’Etudes Spatiales (CNES). It was intended that the data from sever

penetrators and experiment packages, which were to be placed on the surface by th

Russian Mars 94 spacecraft toward the end of the mission, would be relayed to Ear

by this equipment. 

The mission was lost three days before it was due to enter Mars orbit to begin its p

mary mission. When the downlink fell silent at approximately 6 p.m. PDT on 21 Augu

1993, the spacecraft had traveled almost eleven months into the cruise phase of the m

sion with no problems and had taken its first and only photograph of Mars.

For months after the loss of the downlink, ground controllers tried to reestablish com

munication with the spacecraft but were unsuccessful. NASA quickly established a

independent review board to determine the most likely cause for the failure and bega

to lay plans for a new mission to return to Mars.

Mars Observer Mission

The Mars Observer spacecraft was the first JPL “all X-band spacecraft.” It represented th

final transition of X-band technology to full operational status in the DSN. Ironically, 

also carried with it an experiment to demonstrate the next generation of telecommunic

tions technology, the use of Ka-band for space communications. Equipped with an X-ban

uplink and two X-band downlinks, the spacecraft used a high-gain antenna and a low

gain antenna for transmitting and two low-gain antennas for receiving the X-band uplin

The new DSN 34-m HEF antennas with X-band uplink and downlink capability we

selected to provide most of the daily communications with the spacecraft. While Ma

Observer benefited from the general upgrades to the Mark IVA, several specific improv

ments were made to support the mission. These improvements included the Standa

Format Data Unit (SFDU) headers for all data types except command; the Reed-Solomo

32

The Galileo Era: 1986–1996
decoders at each Complex; and the X-band acquisition aid antenna, mounted on th

26-m antenna at Canberra, to ensure the initial acquisition of the X-band downlink 

first view after launch. 

By agreement with the Multimission Operations Systems Office (MOSO) and the Ma

Observer project, all DSN data, with the exception of radio metric data, was to be rou

ed to the project data base via the new Advanced Multimission Operations Syste

(AMMOS). Radio metric data would be routed to the DSN Multimission Navigatio

Team for preprocessing before delivery to the project.29

The Mars Observer launch marked a change in NASA launch policy back to expen

able launch vehicles for interplanetary launches, after ten years of Space Shuttle-bas

launch policy. For the DSN, this resulted in some simplification of prelaunch interfac

and data flow paths compared to those required by Shuttle-based launches, but it al

meant that new interfaces and agreements had to be negotiated, and data flow pat

verified, before launch.

Mars Observer was placed into Earth orbit on 25 September 1992, by a Titan III firs

stage vehicle launched from the Cape Canaveral Air Force Station, Florida. A Transf

Orbit Stage (TOS) booster later injected the spacecraft onto a direct ascent trajecto

to Mars. Initial acquisition of the X-band downlink via the spacecraft low-gain ante

na was rapidly accomplished by the Canberra 26-m and 34-m antennas, and the spacecra

settled into routine cruise activity, supported by the DSN 34-m subnet. After the fir

30 days of continuous tracking, the DSN planned to support the cruise portion of th

mission at a rate of one or two passes per day until the end of July, when full 34-

support on the HEF antennas would again be required for orbital operations. Scien

instrument calibration and checkout was completed, and the instruments began retur

ing data. 

In January 1993, the spacecraft switched to the high-gain antenna with no problem

and a downlink telecommunications experiment using a low-power Ka-band transm

ter on the spacecraft was carried out. The Ka-band Link Experiment (KABLE) w

designed by the DSN to test the capabilities of Ka-band (9-millimeter wavelength) rad

ation for use in future downlink telecommunications. The DSN research and developme

station, DSS 13 at Goldstone, was provided with the necessary antenna and receivin

equipment to perform the tests.30 Excellent results were obtained, and the plan was 

repeat the experiment periodically throughout the cruise period. 

328

Uplink-Downlink: A History of the Deep Space Networ
During the cruise period, over a span of three weeks, Mars Observer participated in 

gravitational wave search with Ulysses and Galileo. The X-band Doppler data was deli

ered to the Radio Science Team for later analysis.

Reports from the Flight Team indicated that all spacecraft subsystems and instrume

payload were working well. The first picture of Mars was taken on 26 July, on

month before the spacecraft was due to arrive at the point of Mars Orbit Insertio

(MOI). As the flight teams began preparing for MOI and the start of orbital ope

ations, the DSN increased its tracking support to a full three passes per day on th

34-HEF subnet.

MOI was programmed to start on 24 August with a 29-minute burn of the spac

craft propulsion system. On Saturday, 21 August, as part of the pre-programmed orb

insertion sequence, the spacecraft downlink was turned off to protect the transmitt

tubes from possible shock effects as the propellant fuel tanks were pressurized. Th

spacecraft was programmed to turn the downlink back on after pressurization ha

been completed.

The expected downlink never appeared. A declared spacecraft emergency condition ga

Mars Observer first priority in use of DSN antennas for downlink recovery efforts. Th

spacecraft failed to respond to repeated uplink commands to turn the transmitter o

to switch to the low-gain wide-beam antenna, switch to a backup timer, and vario

other actions related to possible failure scenarios. 

All three DSN complexes responded to the emergency with continuous commandin

sequences and closely-monitored receiver and signal detection searches. As the days passe

each possible failure scenario was explored, but to no avail. At the end of Septemb

an attempt was made to activate the radio beacon on the CNES radio package in th

hope that its weak (1-watt) downlink might be detected to gave some indication of th

location and condition of the spacecraft. The Jodrell Bank radio telescope in Englan

was enlisted to aid the DSN 70-m antennas in the search. Again, no signal was detec

ed after several days of searching. 

Soon after the loss of downlink occurred, an independent review board was establish

by NASA to determine the most likely cause of the failure. This anomaly investigatio

was augmented by a special technical review board set up by JPL. The findings of bo

boards were generally consistent and pointed to a rupture in the pressurization system

If this were the case, Mars Observer would have tumbled out of control until the pre

surant and fuel were completely exhausted. Then, electrically damaged beyond recover

32

The Galileo Era: 1986–1996
the spacecraft would have overshot Mars to become a mass of space debris in a pe

petual elliptical orbit around the Sun. 

Deep Space Extended Missions

The Pioneer Missions

The Pioneer program was officially terminated by NASA Headquarters on 31 Mar

1997. For thirty-two years, since the launch of Pioneer 6 in 1965, the family of Pione

spacecraft had maintained a presence as prime or extended missions on the DSN trac

ing schedules. 

Pioneers 6 through 9 were launched from 1965 through 1968 into heliocentric orb

to make particles and fields measurements inward and outward from these orbits. In th

later years, they were also used to observe the ultimate longevity and failure modes 

aging flight components such as solar panels, Sun sensors, data handling systems, an

radio transmitters and receivers. Pioneer 9 was last tracked by the DSN in May 198

The DSN continued to maintain downlinks with Pioneers 6, 7, and 8 until the Pione

program was terminated in 1997. Although Pioneers 7 and 8 had developed problem

by then, Pioneer 6 was still operating normally. An unofficial attempt to reestablish co

tact with Pioneer 6 was made from DSS 63 in July 1997. Responding to a sequence 

commands to switch to its backup transmitter, the spacecraft activated a coaxial swit

and turned on the backup Traveling Wave Tube (TWT) amplifier for the first time 

30 years. Although the signal received by the DSN was weak (-165), and the signal 

noise ratio was poor (3 dB), a small amount of Plasma Analyzer data was received. Th

DSN continued to monitor the spacecraft from time to time for the engineering inte

est it provided on long-duration deep space missions.

Pioneers 10 and 11 were launched in 1972 and 1973 to explore Jupiter and Saturn. Th

planetary encounters were used to place them on trajectories that would take them towa

the edge of the heliosphere and eventually out of the solar system. Pioneer 11 reached 

distance of 44.1 AU before its downlink was lost on 30 September 1995. It was su

mised that Earth had moved out of the spacecraft high-gain antenna beam after th

spacecraft could no longer be oriented to keep it pointed in the right direction. Th

downlink from Pioneer 10 was still active when the program was terminated in 1997. A

with Pioneer 6, DSN interest in the longevity and performance of the downlink promp

ed an attempt to contact the spacecraft from DSS 14 on 31 July 1997. The spacecra

downlink was detected at a signal level of -178 dbm, and good two-way S-band Doppl

was obtained. At that time the spacecraft was estimated to be at a distance of 68.65 AU

330

Uplink-Downlink: A History of the Deep Space Networ
For most of their long lives, the Pioneer 10 and 11 spacecraft were able to benefit fro

the periodic enhancements to DSN downlink capability which were driven not by th

Pioneers but by the requirements of other spacecraft. In that sense, they never becam

obsolete and never reached the predicted limit of the DSN capability to maintain a

uplink and a downlink with them.

Pioneers 12 and 13 were Venus Orbiter and Venus Multiprobe missions, respective

Launched about three months apart, they both reached Venus in December 1978. Pione

13 was destroyed on atmospheric entry, but Pioneer 12 remained active in Venus orb

for 14 years. Over the years, the orbit gradually decayed to the point where it could n

longer be raised to prevent aerodynamic damage to the spacecraft. The mission end

when no downlink was detected by the DSN after periapsis passage on 9 October 199

These pioneering spacecraft paid enormous scientific dividends over the more than th

ty years of their diverse explorations of the solar system. Relatively inexpensive by planeta

spacecraft standards, the Pioneer spacecraft established a basis for further exploration b

more complex, more costly spacecraft.31 Furthermore, they amply demonstrated the val

of simple, highly reliable design principles in producing long-lived spacecraft downlin

for deep space communications. 

International Cometary Explorer (ICE)

Following its successful passage through the nucleus of the Comet Giacobini-Zinner 

September 1985, the ICE spacecraft continued to move along its highly elliptical orb

around the Sun as the DSN moved from the Voyager Era into the Galileo Era. Its scie

tific objective was to gain knowledge of how the Sun controls Earth’s near-space environmen

Throughout the Galileo Era, ICE remained on the DSN tracking schedules as an exten

ed deep space mission, supported on the 34-m subnet for a few passes per week 

tracking time became available. Although the spacecraft transmitted no telemetry, th

downlink carrier was recorded by the DSP during each short duration pass, and th

data was delivered to the Radio Science Investigator for analysis.

Voyager Interstellar Mission

The Voyager Interstellar Mission (VIM) began in October 1989, right after the Voyag

2 Encounter of Neptune, and included both Voyager spacecraft. The objectives of th

prolonged mission were to sample the interplanetary medium, conduct ultraviolet ste

lar astronomy, and search for the heliopause, the region where the Sun’s magnetic influen

33

The Galileo Era: 1986–1996
wanes and interstellar space begins. The spacecraft were expected to operate for anot

er twenty-five to thirty years, after which the supply of electrical power generated b

the RTGs would drop too low to operate the science instruments.

Voyager 1 was exiting the solar system at the rate of 525 million km per year on a hea

ing 35 degrees above the ecliptic plane. By late 1992, it was more than 50 AU fro

Earth. At the same time, Voyager 2, diving below the plane of the ecliptic at a 48 degr

angle, had reached a position more than 38 AU from Earth. All seven science instr

ments needed for the VIM were operating well; others designed for the earlier planeta

mission had been turned off in 1990 to conserve power.

After the Neptune Encounter, the level of DSN support for Voyager was reduced 

periodic contact on the 34-m antennas consistent with the new requirements of th

VIM and the availability of antenna tracking time. 

With the exception of the Plasma instrument on Voyager 1, all instruments on bo

spacecraft continued to collect science data and return it to the DSN. The condition 

the radio subsystems on both spacecraft remained unchanged after the initial failures 

1978, and the workarounds developed to cope with them had since been improved an

become normal operating procedure. 

In 1997, the Voyager project developed a plan to extend the Voyager Interstellar Missio

(VIM) for the next twenty-five to thirty years.32 It was estimated that by about the ye

2020, the spacecraft would no longer be able to generate sufficient electrical power f

continued operation of the science instruments. Until then, both spacecraft had th

potential to maintain their present capability for acquiring fields, particles, and wave sc

ence data in the interplanetary and possibly the interstellar regions.

A completely new sequencing strategy was required for spacecraft operations to provi

for acquiring the desired science data, dealing with spacecraft anomalies, and maintai

ing each spacecraft’s high-gain antenna continuously pointed toward Earth.

Not only were the VIM sequence designers constrained by the limited available onboa

computer memory (1,700 words total), but the duration of the VIM introduced man

considerations of special interest to the DSN.

The baseline sequence was stored in the spacecraft computer memory; it contained, 

addition to a continuously executing set of spacecraft operating instructions, the HG

pointing information required to maintain the uplink and downlink with the DS

332

Uplink-Downlink: A History of the Deep Space Networ
through the year 2020. All of the spacecraft events that required 70-m coverage f

best downlink telemetry data return were planned to occur over the Goldstone Compl

for Voyager 1 and over the Canberra Complex for Voyager 2. The timing of spacecra

events had to be adjusted by the onboard sequence to keep them synchronized wi

station view periods. It was also necessary to avoid designated station quiet periods—

Thanksgiving, Christmas, and New Year’s Day—and to allow for the steady increa

in one-way light time of approximately one half-hour per year of flight. For a sho

mission, these were trivial matters, but in terms of a potential thirty-year mission, th

became very significant. 

In September 1997, both spacecraft had been operating in deep space for twenty yea

Voyager 1 was 68 AU from the Sun; Voyager 2 was 53 AU from the Sun. Traveling 

the speed of light, the radio signal from the spacecraft took nine hours to reach th

DSN antennas on Earth. The DSN receiving capability had improved over these yea

to the point where the new 34-m antennas could support a downlink data rate of 16

bps at these great ranges. Return of the recorded plasma-wave data was possible at 7

kbps from Voyager 2, and 1.5 kbps from Voyager 1 on the 70-m antennas using the hig

power X-band transmitters on the spacecraft. Most of the Voyager support was ther

fore carried on the 34-m subnet. In a typical week in 1997, the DSN scheduled 60 

80 hours of antenna time for each Voyager spacecraft, only 5 percent of which was pr

vided by a 70-m antenna. 

Earlier in their missions, Voyagers 1 and 2 had revealed the scientific beauty of Jupit

Saturn, Uranus, and Neptune. In doing so, they challenged the DSN to match th

spacecraft’s ability to capture the data with a capability to receive it. As both spacecra

slowly stretched the existing communications links toward the boundary of the solar sy

tem, the DSN faced the same challenge. The Voyager Interstellar Mission afforded th

DSN its first opportunity to demonstrate uplink and downlink communications “to th

edge”—and beyond. 

Earth Orbiter Missions

General 

In 1986, the DSN carried nine Earth Orbiter missions on its tracking schedules. Tw

of these missions were of the reimbursable type, one French and the other German 

origin. All the Earth Orbiters were supported on the single 26-m subnet, which ha

become a DSN responsibility under the Networks Consolidation program of 1983–8

By 1997, the number of Earth Orbiter missions on the DSN schedules had increas

33

The Galileo Era: 1986–1996
to twenty-three, seven of which were the reimbursable type of Japanese, German, 

French origin. All missions were divided among the 9-m, 26-m, and 34-m networ

as appropriate.

The growth of DSN involvement with Earth orbiting missions is shown in the tab

below. The number of deep space missions being tracked by the DSN in the same tim

period is included for comparison.

Growth of Earth Orbiter Missions Supported by the DSN, 1986–97

Missions 1986 1988 1990 1992 1994 1995 1996 1997

NASA

Earth 

Orbiter 7 5 4 4 9 19 16 23

Non-NASA

Earth

Orbiter 2 5 7 3 1 5 3 4

Deep Space 12 11 13 13 12 10 9 10

Under the terms of a reimbursable agreement, the space agency owning the spacecra

was charged an hourly fee by NASA for the use of the DSN antennas. In the ear

agreements, the costs for antenna time, supporting services, technical management, an

travel were detailed separately. Later, these costs were combined into a standard fee bas

on the antenna type. 

The reimbursable rate for the 26-m or 34-m antennas was established in 1993 at $2,82

(U.S.) per hour. By 1995, the rate had been reduced to $2,080 and further reduced 

$1968 by 1997, due to economies in manpower required for station operations fun

tions. The reduction in human resources required for DSN operations reflected th

greatly expanded capabilities of improvements in the Mark IVA DSN Monitor an

Control System. Corresponding hourly cost (in U.S. dollars) for the 70-m antennas w

$5,650 in 1993, reduced to $4,160 by 1995 and to $3,936 by 1997.

The NASA strategic plan of 1995 called for the “transfer of operational activities, as fe

sible, to other federal agencies or commercial operators.” In response, the Telecommunicatio

and Mission Operations Directorate (TMOD) conducted a study to estimate the ec

nomic viability of using a commercial service as an alternative to NASA-provided trackin

and data acquisition services for low-Earth orbiter (LEO) and high-Earth orbiter (HEO

334

Uplink-Downlink: A History of the Deep Space Networ
missions. The results of the study were presented to the NASA Space Operations Offi

(Code O) in October 1995 and included a recommendation that the DSN 26-m subn

be closed by the end of fiscal year 1997. The antennas were to be decommissioned, an

the equipment not needed by JPL was to be declared “surplus property” and disposed 

appropriately. Procurement action for commercial services equivalent to those provided b

the 26-m subnet was initiated with a target transfer date of September 1997.

Before these recommendations were implemented, however, a new proposal for a more cos

effective solution to the disposition of the 26-m network was evaluated by TMOD. Th

resulted in a final recommendation that the 26-m subnet be automated and utilized to su

port low- and high-Earth orbiting missions through the year 2001. By that time, suppo

for low-Earth orbiters was to be provided by commercial services and support for the hig

Earth orbiters would continue to be provided by the fully automated 26-m subnet.

With the authority of the new Space Operations Management Organization (SOMO), dire

tives to this effect were issued to the Mission Services Managers at JPL and other NAS

Field Centers in March 1997 by the Space Operations Data Services Manager. Within JP

this directive provided TMOD with the formal instructions it needed to proceed with autom

tion of the DSN 26-m subnet and the eventual transfer of low-Earth orbiting missions 

a commercial service. Planning toward these objectives began to move forward. 

Emergency Mission Support 

The introduction of the Tracking and Data Relay Satellite System (TDRSS) from 1983 

1985 as an alternative to ground-based stations for tracking satellites in low-Earth orb

required that provision be made for emergency support in the event of failure of the TDRS

satellites, or failure of the ground station at White Sands, New Mexico. In 1983, a DS

study had shown that for a nominal cost, the 26-m subnetwork of antennas being tran

ferred to the DSN under the Networks Consolidation program could be utilized to provi

the necessary support for a limited set of emergency situations.33 After approval of the co

cept by the NASA Office of Tracking and Data Acquisition (OSTDS), the necessary interfac

and operational procedures were developed to allow timely notification of an emergency s

uation by the Flight Projects Directorate at GSFC, and a prompt response by the DS

Operations organization at JPL. The procedures provided for the exchange of informatio

needed by the DSN stations to point the antennas, acquire the uplinks and downlink

transmit commands, and record and deliver the desired telemetry and ranging data. 

The original list of eight Earth-orbiting missions approved for emergency DSN suppo

under this agreement included the Hubble Space Telescope, the Space Shuttle, and th

33

The Galileo Era: 1986–1996
TDRSS satellites. Through the next decade, Hubble, Shuttle, and TDRSS remained o

the DSN schedules as “emergency support only” missions, while changes and additio

to the original list brought the total to twelve by 1997.

Except for the coverage provided by the Goldstone 9-m and 26-m antennas for eme

gency Shuttle landings at Edwards Air Force Base at Mohave, California, the need f

emergency support under the terms of this agreement occurred only once or twice p

year in the twelve years after its inception. Shuttle support was phased out of the 2

m schedules in 1997.

Beginning in 1995, international agreements for providing emergency support for low

Earth orbiting spacecraft were negotiated among NASA (U.S.), NASDA (Japan), CNE

(France), and DLR (Germany). Under these agreements, the various space agencies agre

to provide emergency support for foreign spacecraft on the antennas of each othe

tracking networks, as appropriate to the particular situation.34 Emergency support w

defined to be a period of unscheduled tracking, telemetry, and/or command suppo

necessary for spacecraft survival in the event of a spacecraft emergency. The suppo

would be provided by existing resources on a best-efforts basis, would be of short dur

tion, and would involve no exchange of funds or liability. Only S-band uplinks an

downlinks would be used for spacecraft communications, and the support would be lim

ited to satellites launched for peaceful purposes only. A key element of the agreemen

was a listing of the mission sets for which emergency support might be requested. Th

DSN antennas designated for this type of service included DSS 16 and DSS 27 

Goldstone, DSS 46 at Canberra, and DSS 66 at Madrid. 

Lower level agreements in the form of Interface Control Documents (ICDs) were deve

oped to manage the technical interfaces, communication configurations, protocols, operation

procedures, and delivery of data products. The reciprocal exchange of telecommunicatio

services between the agencies was viewed by the parties to the agreement as mutually be

eficial. At the time of this writing, there have been no calls for support of this kind. 

336

Uplink-Downlink: A History of the Deep Space Networ
NETWORK ENGINEERING AND IMPLEMENTATION 

The 70-meter Antennas

Reporting on the maintenance, rehabilitation, and upgrade of the DSN 64-meter antenn

in March 1982,35 the DSN chief engineer, Robertson Stevens, focused attention on the h

tory and status of the hydrostatic azimuth bearings and azimuth radial bearings, particular

those at DSS 14 and DSS 43. He also recommended a plan for continuing repair or replac

ment of components and the continuing upgrade of maintenance and operating procedure

The report also argued convincingly that it was indeed practical to enlarge the antennas 

70-meter diameter and to extend the useful operating frequency for these antennas.

Over the next several years, while the Network continued to support all flight m

sions described in the previous chapter, these recommendations were implemente

This work included the three 70-m upgrades, the last of which was completed at DS

14 in May 1988.

By 1989, the Goldstone antenna had been in continuous operation for 23 years, and t

overseas antennas had been in operation for 16 years. The specified design life for par

subject to wear was 10 years. The antennas had been specified and designed more than 2

years earlier. They had performed remarkably well, but with a resurgence in the number 

planetary missions planned for the Galileo Era, even more was to be demanded of them

To this end, a DSN Antenna Rehabilitation Team36 was established in March 1989 

identify the resources needed to maintain the new 70-m antennas past the year 200

The team recommended five high-priority tasks it believed would, if promptly impl

mented, extend the useful operating life of the antennas for the next twenty-five yea

The tasks were to develop a trend analysis program to provide early detection of inci

ient failures; to provide a means of lifting the antenna in the event that a pad or b

joint needed to be replaced, as had occurred in Spain and Australia in 1976; to repa

or replace aging structural and mechanical elements of the antenna before further det

rioration took place; to rehabilitate the elevation and azimuth gearboxes, since the ge

drive assemblies ranked next to the hydrostatic bearing in the number of problems exp

rienced over the years; and to replace the subreflector positioner and controls becau

these had been a longstanding source of trouble.

The hydrostatic bearings at Spain and Australia were believed to be in good conditio

and were not expected to require any special attention in the foreseeable future. Howev

33

The Galileo Era: 1986–1996
there was less confidence in the future of the hydrostatic bearing at Goldstone. It w

hoped that existing procedures to inhibit rust formation would be successful and th

major rework would not be necessary. Only time would tell.

It was the opinion of the team that the basic design was sound and that, under no

mal operating conditions, the structure was not subjected to high stress levels. At th

time, cyclic stresses were considered to be infrequent and of a low level, so fatigue 

catastrophic failure was thought to be unlikely.

Elevation Bearing Failure 

About the time that the 70-m Rehabilitation Team was publishing these findings (Novemb

1989), the Galileo spacecraft was reaching the point where it became dependent on conti

uous support from the 70-m antennas to sustain the downlink telemetry data rate of 1,20

bps needed for its rapidly approaching Encounter with Venus on 9 February 1990. Close

approach would occur during the DSS 43 overlap with DSS 63, and full 70-m covera

was essential to the success of this first gravitational-assist event in the Galileo mission 

Jupiter. On 13 December 1989, in the midst of this intense 70-m activity, the right-si

inboard elevation bearing on the DSS 63 antenna failed, and the antenna was immobilize

The failure occurred about 9:00 a.m. (local time) while the antenna was being used 

investigate some anomalous Doppler problems at low elevation angles. It appeared th

one or more of the rollers in the roller bearing race that supported the right inboa

elevation bearing had cracked. The bearing sustained further damage when the antenn

was driven back to the zenith position for safety. The extent of the damage can be appr

ciated by the photograph of the damaged bearing shown in Figure 5-25.

Obviously, a very serious antenna bearing problem now existed. The situation was exa

erbated by pressure from Galileo, the approaching holidays, and arduous working conditio

due to inclement winter weather in Spain.

The DSN immediately dispatched several antenna engineers to Madrid to investigate t

problem. Dale Wells, one of the engineers involved in the mechanical maintenance of 

three large antennas since they were first built, remained on site to direct the repair wor

while other technical staff at JPL coordinated the shipment of spare bearings and other par

The unusual nature of the repair work required special tooling, much of which was fa

ricated on site. The right side bearing, carrying two million pounds of antenna weigh

was lifted with hydraulic jacks, and removal of the damaged bearings began. This prov

338

Uplink-Downlink: A History of the Deep Space Networ
to be extremely difficult and was eventually accomplished by flame-cutting some of th

retaining bolts and sections of the damaged race. Once the old bearing parts were remove

installation of the new bearings proceeded rapidly, and the antenna was tested and return

to service on 25 January, fifteen days before the Galileo encounter with Venus. The br

ken bearing was carefully reassembled and returned to JPL for evaluation. 

An Elevation Bearing Failure Team was formed in January to investigate the DSS 6

failure and to oversee any remedial action that might be needed at the other 70-m ante

nas. The team first decided to return the broken bearing to SKF for a bearing failu

analysis. There, it was determined that the failure had been caused by fatigue of th

inner bearing rollers, which, over the years, had caused metal particles to flake off an

damage the surfaces of other rollers in the bearing. This progressive action ultimate

led to complete lockup of one roller, and eventually to failure of the entire bearing rac

Following the DSS 63 return to service, the elevation bearings on all the 70-m ante

nas (including those at DSS 63) were inspected in sequence for signs of wear. Som

signs of wear were found, but none that warranted a change of the bearing races at th

33

The Galileo Era: 1986–1996

Figure 5-25. Cracked bearing rollers and inner race, DSS 63, December 1989.
time. It was decided to continue with regular analysis of bearing for detection of met

particles. This work, requiring only two days of antenna downtime at each site, was ca

ried out during April and May of 1990. 

The team also directed that the loads on each of the inboard and outboard elevatio

bearings on all three antennas be equalized to correct the additional, unequal loading th

resulted from the 70-m upgrade. This work was sufficiently important to require 21 da

of antenna downtime, beginning immediately at DSS 63. It was fortuitous that the Galil

spacecraft was approaching its first Earth fly-by around this time, and consequently 

need for 70-m support was minimal. The work was completed at DSS 14 in Janua

1991. In some cases, before the load equalization adjustment, the inequality of load sha

ing between the inner and outer bearings was as much as 80 percent to 20 percent. Wi

the work completed, this was reduced to, typically, 55 percent to 45 percent or better

Finally, the Team recommended that the original roller bearings, which were manufactur

with 3/4-inch axial holes to facilitate the heat treatment process, should be replaced wi

solid roller bearings. Orders for new bearings were placed, and the work of replaceme

began in May 1991 at DSS 63. Using their experience and tooling from the previous bea

ing replacement effort, the engineers completed the work in just 17 days. To economize o

antenna downtime, replacement of the elevation bearings at DSS 43 and DSS 14 was ca

ried out in 1993 and 1994, in conjunction with the upgrade of the elevation gearboxes

Gearbox Rehabilitation

The primary motive power to drive the huge 70-m antennas in the azimuth and el

vation directions is provided by hydraulic motors activated by computer-controlled serv

systems. The high-speed output shafts of the hydraulic motors are connected to the va

ious low-speed gears (pinions) and quadrants. These physically rotate the antenna b

using reducer gearboxes—four for the elevation drive and four for the azimuth drive

Ever since the antennas were first built, persistent problems with the gearboxes had be

constant cause for concern and led to expensive and antenna-time consuming repair effor

Until about 1984, most of the gearbox problems were related to lubrication matters, b

in 1985, a significant increase in the wear patterns on all antenna drive components, pa

ticularly the gearboxes, became evident. This was attributed to the introduction of th

1985 Mark-IVA servo modifications described in the previous chapter. The new serv

drove the antennas at maximum velocity between the “stow” and “track” positions, an

vice versa, causing additional wear and even inducing oscillations in the overall system

In addition, the increasing DSN tracking schedule in that period called for more rap

340

Uplink-Downlink: A History of the Deep Space Networ
changes between multiple spacecraft; also, VLBI, clock synchronization, and Star Catalog

passes required frequent and rapid slewing of the antennas, with fast starts and stops.

By 1986, the situation had become serious enough on the DSS 14 antenna to warrant a

examination and evaluation of wear on the elevation bull gear and pinion by a profe

sional consultant from the University of California at Berkeley. On the basis of this evaluatio

the elevation pinion gears at DSS 14 and DSS 43 were replaced with specially harden

gears in 1987 as part of the 70-m upgrade. Gear replacement was not required at th

time at DSS 63. In April 1988, an expert consultant specializing in gear train systems w

sought to examine and report on the condition of the gearboxes themselves. The two sp

cific recommendations called for replacing the drive train gearbox components wi

case-hardened and precision-ground gears, and adding magnetic particle detectors to t

lubrication systems to remove wear debris. DSN engineers responded with a contract 

the Philadelphia Gear Company in 1990 for a completely new set of components 

upgrade or replace the existing 24 gearboxes on all three 70-m antennas. The new desig

incorporated the experts’ opinion and the DSN engineers’ experience with the origin

design, which had provided approximately thirty years of continuous operational servic

Installation of the new gearboxes began with DSS 43 in March 1993 and proceed

around the Network as downtime could be scheduled, to DSS 14 in September 199

and DSS 63 in June 1994.

Subreflector Drive Problems

The considerations that led the 70-m Antenna Rehabilitation Team in 1989 to recom

mend complete replacement of the subreflector suspension and drive systems result

from the inadequate design of the 70-m components. Constrained in many ways by th

design of the former 64-m components, they simply were not robust enough to hand

the much larger and heavier subreflector used on the 70-m antennas. Frequent failur

and problems occurred, and several modifications and temporary work-arounds we

necessary to keep the antennas in operation. Because the estimated cost of the work w

3.6 million dollars, budget constraints at the time prevented the recommendations fro

being implemented immediately, and the matter was deferred.

However, before anything more could be done in this regard, nature itself intervene

On Sunday 28 June 1992, just as the DSS 14 antenna was being rotated to the ho

zon in preparation for a Pioneer 10 spacecraft track, the Goldstone area was hit by tw

severe earthquakes within a few hours of each other. 

34

The Galileo Era: 1986–1996
In the shaking that followed, the 24,000-pound subreflector broke loose from the thre

axis drive shaft and impacted the quadripod suspension structure. The cast aluminu

subreflector was severely damaged, and its precision-contoured surface was cracked an

holed. All antennas at Goldstone were halted while damage was assessed. As it turned ou

only DSS 14 had sustained permanent damage, and repair started immediately. At first 

was thought that the subreflector would have to be replaced, and action was started 

ship the fiberglass subreflector that had been used several years earlier at DSS 43. Howev

it was eventually decided that the subreflector and its drive system should be repaired 

place, over 71 meters above the ground, with the antenna at zenith. Over the next thr

weeks, all the damaged parts of the subreflector and its three-axis drive system were eith

repaired or replaced, and the antenna was returned to full operation on 22 July 199

After necessary mechanical and optical realignment adjustments were made, it was es

mated that the loss of RF gain attributable to damage inflicted by the earthquake (an

subsequently repaired) was no greater than 0.06 dB at X-band. This small performan

loss was within acceptable limits, and the antenna was approved for full operational us

On 1 July 1992, right after the earthquake occurred, an Engineering Analysis and Correcti

Actions Team was formed to analyze the damage, assist with the return to service action

and recommend corrective action to improve the protection of the 70-m antennas fro

future earthquake damage. In 1995, as a result of the team’s findings, new earthquak

resistant subreflector positioners were designed, built, and installed on all 70-m antenna

The 70-m antenna mechanical specifications were changed to better match an earthquak

prone environment, and future antenna designs reflected the need for seismic protectio

Seismic monitoring procedures were established for the Goldstone antenna using accelerom

eter sensors located at strategic points in the base and apex areas of the antenna.

There have been no further earthquake incidents in the DSN as of this writing.

Toward the end of the Galileo Era, the funds available for antenna maintenance we

significantly affected by overall reductions in the DSN budget. Out of this situatio

yet another review board emerged to report on the physical condition of the 70-m an

34-m antennas. Based on these findings, the board was to recommend cost-effecti

measures that would assure their continued reliable operation in the forthcoming pe

od of diminished resources. 

The board was chaired by Richard P. Mathison, then chief engineer, and included se

eral experts from the National Radio Astronomy Observatory (NRAO) with experien

in large antennas, and some with knowledge of telescope (Keck) mounting structure

342

Uplink-Downlink: A History of the Deep Space Networ
In late 1996, the board inspected the antennas at each of the three sites and close

examined specific onsite maintenance problems with the engineers involved.

The board concluded that the condition of the antennas and the level of maintenan

at all sites was uniformly good. It expressed concern for incipient failures in several 

the steel and concrete elements of the 70-m structures and recommended a continuin

program of monitoring and inspection to establish trends in performance deterioratio

To reduce antenna maintenance costs, the board suggested that the DSN should clea

ly establish an absolute minimum level of maintenance required for reliable operatio

for all 70-m antennas. This would enable proper allocation of funding between th

requirements for minimum maintenance, preventative and corrective maintenance, an

the replacement and procurement of spare parts.

In 1997, it was generally believed that the 70-m antennas were in sound mechanic

condition, that their potential structural and mechanical weaknesses were well unde

stood and under control, and that with the recommendations of the Mathison Revie

Board in effect, they would continue to provide reliable uplink and downlink servi

well into the new century.

Interagency Arraying

Parkes-Canberra Telemetry Array

As early as 1981, advanced systems planners in the DSN had begun to evaluate the po

sibility of enhancing the downlink performance of the DSN 64-m antennas for speci

short-duration mission events of high science value, such as the future Voyager Encounte

with Uranus and possibly Neptune, by arraying other large, non-DSN antennas wi

those of the DSN. These ideas followed naturally from the DSN’s long history of arra

ing with its own 64-m and 34-m antennas, summarized in Figure 5-26. 

Because of its past associations with the DSN and reasonably close proximity to Canberr

the 64-m antenna of the Radio Astronomy Observatory in Parkes, New South Wale

Australia, was the first non-DSN antenna to be considered for this purpose. This fac

ity, owned and operated by the Australian Government’s Commonwealth Scientific an

Industrial Research Organisation (CSIRO), formed the basis for much of the early desig

work on the DSN’s own 64-m antennas twenty years earlier. 

After the necessary high-level agreements between CSIRO and NASA were complete

a technical design for a Parkes-CDSCC Telemetry Array (PCTA) was initiated.37 At th

34

The Galileo Era: 1986–1996
time, the PCTA was designed specifically to meet the downlink requirements of th

January 1986 Voyager Encounter with Uranus. It was estimated that the addition of th

64-m Parkes antenna to the CDSCC configuration of one 64-m antenna arrayed wi

two 34-m antennas could increase the downlink capability for the Voyager/Uran

Encounter by as much as 50 percent.

344

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-26. Twenty years of telemetry arraying in the DSN.

Location

Mission Datea of Antenna Combiners c

antennas types

Pioneer 8 1970 Spain 26-m + 26-m Passive BB

Mariner Venus-Mercury

(Mercury) Sept. ’74 U.S. 64-m + 2 (26-m) R&D BB

Voyager 1

(Jupiter) Mar. ’79 U.S. 64-m + 34-m RTC

Voyager 2

(Jupiter) Jul. ’79 U.S. 64-m + 34-m RTC

Pioneer 11

(Saturn) Sep. ’79 U.S. 64-m + 34-m RTC

Voyager 1

(Saturn) Aug. ’80 ALL DSCCs 64-m + 34-m RTC

Voyager 2

(Saturn) Aug. ’81 ALL DSCCs 64-m + 34-m RTC

International Cometary

Explorer (Giacobini-Zinner) Sep. ’85 ALL DSCCs 64-m + 34-mb Passive BB

Spain/U.S. 64-m + 64-m SSRC R&D

Australia/Usuda 64-m + 64-m SSRC R&D

Voyager 2

(Uranus) Jan. ’86 Spain 64-m + 34-m RTC/BBA

U.S. 64-m + 2 (34-m) RTC/BBA

Australia 64-m + 2 (34-m) RTC/BBA

+Parkes 64-m + LBC

+ SSRC R&D

Voyager 2

(Neptune) Aug. ’89 Spain 70-m + 2 (34-m) RTC/BBA

U.S. 70-m + 2 (34-m) RTC/BBA

+ VLA 27 (25-m) + VLBC

+ SSRC

Australia 70-m + 2 (34-m) RTC/BBA

+Parkes 64-m + LBC

+ SSRC

a Listing of month and year indicates encounter period. b The Spain and U.S. 64-m antennas also combined dual channels with passive BB. c BB = Baseband (symbol-modulated subcarrier).

LBC = Long Baseline Combiner (baseband at ~300 km).

RTC = Real-Time Combiner, first version (baseband at ~30 km).

RTC/BBA = Operational RTC—part of BBA (Baseband Assembly).

SSRC = Symbol-Stream Recording and Combining (non-real time).

VLBC = Very Long Baseline Combiner (baseband at ~1,000 km).
Prior to NASA’s becoming interested in seeking the support of CSIRO for the use 

the Parkes antenna for Voyager, the European Space Agency (ESA) had already com

pleted similar agreements for Parkes support of the Giotto mission to Comet Halle

The antenna had been in service for twenty years, and a major upgrade to its facilitie

computers, and servo and pointing capability had just been completed. Under this agre

ment, CSIRO would further upgrade the antenna for operation at X-band. Fortunate

for NASA, the ESA X-band configuration for Giotto was compatible with the confi

uration required for Voyager, and arrangements were made with CSIRO for the tw

agencies to share antenna equipment and tracking time from late 1985 through th

encounters with Uranus and Comet Halley in January and March 1986. 

The low-noise, X-band receiving equipment that was to be shared consisted of a fee

horn provided by CSIRO, a microwave assembly provided by JPL, and two masers bu

in the U.S. to the standard JPL design with funding provided by ESA. The front-en

equipment package was integrated with French designed down converters by ESA 

Darmstadt, West Germany. A video-grade microwave link, of Japanese manufacture, w

supplied by Telecom Australia, to transfer the Parkes data stream to the Canberra Comple

some 350 km distant, for combining with the DSN data stream. 

At first, DSN engineers, with their long history of successful in-house experience, view

the international flavor of the PCTA front-end package with some reservation. Howev

its performance under actual operational conditions left no room for skepticism, and 

performed well for many years afterward, with a minimum of problems.

The functional block diagram of the Parkes-CDSCC Telemetry Array shown in Figu

5-27 identifies the various areas of responsibility among the DSN, ESA/Parkes, Teleco

Australia, CSIRO/Parkes, and the PCTA at Parkes and CDSCC.

As might be expected, the transmission time delay on the 350-km microwave link fro

Parkes to Canberra introduced additional complexity to the combining process. Th

delay was found to be quite stable and equal to 1.2 milliseconds. The effect of this an

other more subtle dynamic delays was provided for by special circuits in the design 

the Long Baseline Combiner. 

Most of 1983 was occupied with negotiating the unique NASA-ESA-CSIRO agreemen

and developing interface design control specifications to ensure that all the elements 

the PCTA would work together when assembled end-to-end. In 1984, fabrication of th

individual elements, including implementation of the intersite microwave link, was 

progress. Testing and verification for compatibility with each other and with the Voyag

34

The Galileo Era: 1986–1996
346

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-27. Parkes-CDSCC telemetry array. In this diagram, the amplified X-band downli

signals from the antennas at Parkes and CDSCC were first changed down to the 300-MH

band to feed the receivers which delivered baseband (subcarrier plus data) signals at their ou

puts. The baseband outputs were treated differently at the two locations. At Parkes, the baseba

signals were digitally recorded at the Mark III Data Acquisition Terminals (DATs) while simult

neously being transferred to CDSCC via the Telcom Australia microwave link. At CDSCC, t

baseband signals from each of the three DSN antennas were first combined in the Baseba

Combiner. The combined composite signal then followed two parallel paths. In one path, su

carrier demodulation and frame synchronization functions were performed by a Demodulati

and Synchronization Assembly (DSA). After decoding and formatting, the data stream w

returned in real time to JPL. On the other path, the baseband signal fed both a DAT (simi

to the Parkes set-up) and a Long Baseline Baseband Combiner. It was in this latter comb

er that the Parkes and composite CDSCC signals were finally brought together for baseba

combining to provide the enhancement expected from the overall PCTA system. This oper

tion was followed by data handling processes identical to those just described. A study of t

diagram will show how the DATs allowed these same operations to be performed in non-re

time whenever the need arose.

64 m

FRONT

END RECEIVER

34 m

FRONT

END RECEIVER

MARK IVA DSN

ESA PARKES

ESA PARKES

CSIRO PARKES

PCTA CDSCC

PCTA PARKES

FORMATTER

DEFORMATTER

BB

COMBINER

BBA 1

RT

RT

DEFORMATTER

DEFORMATTER

DEFORMATTER

NRT

LONG

BASELINE

BB

COMBINER

DSA 1

DSA 2

DSA 1

BBA 2

DSA 2

TSA

FTS

FREQUENCY AND TIMING

OPER

TERM

OPER

TERM

ARRAY

CONTROLLER

ARRAY

CONTROLLER OPER

TERM

BB TEST SIGNALS

INTERFACE

BB

INTERFACE

BB SIGNALS

VOICE

DATA

TO CDSCC FEA’S

MCD/TPA

MCD/TPA

CDSCC

DATA

+

SNR

PARKES

+

CDSCC

DATA

+ 

SNR

PARKES

SNR

NRT

MARK III DAT

MARK III DAT

CONV AND

FORMATTER

300 MHz

RECEIVER

TEST YSIGNAL FACTOR

34 m

FRONT

END

64 m

FEED

ANT.

SERVO

FREQUENCY AND TIMING

FACILITIES

CSIRO PARKES PCTA PARKES

Fig. 2. Parkes=CDSCC Telemetry Arry, functional block diagram

TELECOM PCTA CDSCC MARK IVA DSN

DUAL TWMS DOWN

CONVS

BB TEST SIGNALS

SYSTEM TEMP

CONFIG INDIC

RCVD CARRIER LEVELS

POINTING PREDICTS

POINTING STATUS

RECEIVER
and Giotto spacecraft began in 1985. The Parkes antenna began supporting Voyager an

Giotto passes in September 1985, following a final set of system performance tests 

validate the end-to-end system and a few more weeks of operational verification testin

to refine operations procedures. By the time the Voyager spacecraft began its observ

tory phase in November 1985, the PCTA was running in full operational status an

providing the predicted downlink enhancement that was essential for the successful Voyag

Encounter of Uranus on 4 January 1986.

At the range of Jupiter, 5 AU from the Sun, the maximum downlink data rate fro

the Voyager spacecraft had been 115.2 kbps. By the time the spacecraft reached Satur

at a range of 10 AU, the maximum data rate had fallen to the range of 44.8 kbps 

14.4 kbps. When the distance doubled again to 20 AU at Uranus, the data rate wou

have been about one-fourth of that value, without the PCTA. The enhancement of th

downlink provided by the PCTA allowed the mission controllers to recover telemet

virtually error-free from the spacecraft at data rates of 21.2 kbps to 14.4 kbps. 

The demonstrated operational success of the PCTA during the Voyager Uranus Encount

confirmed the DSN’s confidence in interagency arraying as a viable adjunct to the DS

capability for planetary missions. The future would provide two important occasions o

which the DSN would have good reason to call on these techniques. The first wou

be to enhance an existing mission, Voyager at Neptune, the other to save a disabl

mission, Galileo at Jupiter.

About the time that the PCTA technical studies were being completed in 1982, a broa

er based study of interagency arraying as a potential benefit to DSN capability f

downlink support of planetary missions was initiated. Led by James W. Layland,38 th

study was directed toward determining “which other facilities might be feasibly and be

eficially employed for the support of Voyager at Uranus, and examining th

Voyager/Neptune Encounter and such other future events and options as might appear

In light of subsequent events connected with the Galileo mission to Jupiter ten yea

later, this proved to be a very prophetic vision.

At its conclusion in early 1983, the study recommended that the existing plans for su

port of Voyager at Uranus should be completed. This culminated in the PCTA describ

above. The study also recommended that the arraying configuration for the Voyag

Neptune Encounter should consist of the full array of DSN antennas, plus Parkes, pl

the Very Large Array (VLA) at Socorro, New Mexico. There were some qualificatio

to these recommendations related to budget matters, but they did not affect the cour

34

The Galileo Era: 1986–1996
of history. The comparative downlink performance data on which these recommend

tions were based are shown in Figures 5-28 and 5-29.

The recommendations from this study set the stage for the continuing DSN inte

est in interagency arraying and contributed materially to the success of the Voyag

Encounter with Neptune in 1989, and eventually to the Galileo Encounter wi

Jupiter in 1996.

VLA-Goldstone Telemetry Array

Sponsored by the National Science Foundation (NSF) and operated by the Nation

Radio Astronomy Observatory (NRAO), the Very Large Array (VLA) is a premier rad

astronomy facility located at Soccoro, New Mexico. It consists of 27 antennas, each 2

meters in diameter, arranged in the form of a “Y” with a 20-km radius. This was th

facility that, arrayed with the DSN antennas in Goldstone, California, would be know

as the VLA-GDSCC Telemetry Array (VGTA). 

348

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-28. Enhanced downlink performance at Uranus. 

49

48

47

46

45

44

43

42

41

40

29.9

21.6

19.2

14.4

8.4

7.2

CDSCC +

PARKES

GMT HOURS

GDSCC

64, 34, 34

CDSCC

64, 34, 34

16 20 00 04 08 12

PD/NO

DB Hz

DATA RATE

KILOBITS / SEC

MDSCC

64, 34
The VGTA and its Australian counterpart, the PCTA, would be the DSN key to th

Voyager Encounter with Neptune in August 1989.

By that time, the range to the spacecraft would have doubled again from 20 AU 

Uranus to 40 AU at Neptune. Before that point was reached, however, the DSN 64-

antennas would have been upgraded to 70-m diameter and this, together with the tw

34

The Galileo Era: 1986–1996

Figure 5-29. Enhanced downlink performance at Neptune. In these figures, each curve repr

sents one of the array options from the study. The left-hand scale represents the performance 

the downlink in terms of the ratio of data signal power (PD) to noise power (NO) expressed in d

The right-hand scale shows the Voyager downlink telemetry data rates that correspond to t

downlink performance values. These were the downlink data rates which theory predicted wou

be available 90 percent of the time when weather and other natural effects were taken into accou

The reduction in downlink data rate that results from a 6-dB loss in downlink performance, whi

in turn corresponds to a doubling of Earth-to-spacecraft range, is very evident. The beneficial res

of adding a non-DSN antenna to the existing DSN capability is represented by the performan

curves. The bottom time scale shows the GMT time at which the Voyager spacecraft would 

visible at each longitude during the respective encounters. These figures convey, in a very drama

way, the essential reason for the strong DSN interest in the technique of antenna arraying.

49

48

47

46

45

44

43

42

41

40

39

29.9

21.6

19.2

14.4

11.2

8.4

7.2

GMT HOURS

PD/NO

DB Hz

DATA RATE

KILOBITS / SEC

MDSCC

70, 34, 34

CDSCC

70, 34, 34

GDSCC

70, 34, 34

00 04 08 12 16 20 24

GDSCC

+

VLA CDSCC + PARKES
34-m antennas and the VGTA, would more than double the downlink capability 

Goldstone and offset the loss due to increased range. The PCTA would produce a sim

ilar result at the Canberra longitude. It was expected that these enhancements wou

support data rates at Saturn similar to those that had been used at Uranus, despite th

increased range penalty.

By early 1985, a Memorandum of Agreement and Management Plan for a joint JP

NRAO VGTA Project had been signed by NSF and NASA. The JPL TDA Engineerin

Office would have responsibility for overall planning and management, supported b

implementation and preparation managers at JPL and NRAO. The JPL effort was l

by Donald W. Brown, and the NRAO effort by William D. Brundage.39

Under the terms of these agreements, NASA agreed to bear the costs of installing low

noise, X-band amplifiers on all 27 VLA antennas, as well as the direct costs of preparin

and operating the VLA for Voyager/Neptune support. This would include at least for

monthly tests with Goldstone between late 1984 and early 1989, in addition to for

spacecraft tracks during the Neptune Encounter period in late 1989.

The onsite engineering, installation, test, and operation of the PCTA were managed, 

they had been for the Uranus Encounter, by the staff at the CDSCC in cooperatio

with the staff at Parkes. 

A high-level block diagram of the VGTA is shown in Figure 5-30. 

In the process of reaching the final operational configuration described above, a num

ber of technical problems that were unique to the VGTA design demanded considerab

attention before they were finally resolved.

The problems began with the low-noise front-end amplifiers for the VLA antennas. Th

baseline plan for the X-band low-noise receivers on the VLA antennas included cool

Field Effect Transistor (FET) low-noise amplifiers. By the time the first three receive

had been installed in 1985, new technology offered the promise of significant improv

ment in system noise temperature by the use of the High Electron Mobility Transist

(HEMT) low-noise amplifiers. This translated into an increase of 1.5 dB in the expec

ed overall sensitivity of the VLA. As the HEMT amplifiers became available beginnin

in 1986, tests confirmed the expected improvements, and ultimately all of the VL

antennas were equipped with HEMT amplifiers. It was calculated that when equipp

with HEMT receivers, the VLA would equal nearly three 64-m DSN antennas in term

of downlink performance, a valuable resource indeed.

350

Uplink-Downlink: A History of the Deep Space Networ
For the combining (summing) process to work correctly, the signals from the twent

seven separate VLA antennas must all be in phase with one another. By 1987, with th

aid of new, more powerful computers at the VLA, phase measurements on all antenn

baseline combinations could be made simultaneously. This allowed adjustments for pha

variations along the signal paths to each antenna, caused by fluctuations in the trop

sphere, to be made in near-real time. The resulting ability to track out the effects of th

troposphere, even in the severe summer thunderstorms characteristic of the VLA sit

35

The Galileo Era: 1986–1996

Figure 5-30. VLA-GDSCC telemetry array. In concept and operation, the VGTA closely resem

bles the PCTA described above. The essential features of the VGTA as eventually implement

were 1) X-band reception at the VLA and at GDSCC; 2) full-spectrum combining of 27 separa

signals at VLA; 3) carrier demodulation to baseband at both sites; 4) transmission of the baseba

signal from VLA to GDSCC via an Earth-satellite link; 5) standard baseband combining of one 7

meter and two 34-meter antennas at Goldstone; 6) baseband combining of the VLA and Goldsto

signals in the Very Long Baseline Combiner at GDSCC; 7) convolutional decoding, signal pr

cessing, and data transmission to GDSCC to JPL; and 8) symbol stream recording at both sit

to back up the real-time system and to allow for symbol stream playback and non-real-time com

bining at Goldstone.

25-METER

25-METER

27 ANTENNAS

LOW-NOISE

AMPLIFIER RECEIVER

LOW-NOISE

AMPLIFIER RECEIVER VLA

COMBINER RECEIVER

SATELLITE

TERMINAL

VERY LONG

BASELINE

COMBINER

SYMBOLSTREAM

COMBINER

SYMBOLSTREAM

RECORDER

SYMBOLSTREAM

RECORDER

GPS

RECEIVER FREQUENCY

AND TIMING

DSN VLA

FREQUENCY

AND

TIMING

GDSCC

NRAO VLA

70-METER

LOW-NOISE

AMPLIFIER RECEIVER

DSCC

COMBINER

GDSCC BASEBAND

LOW-NOISE

AMPLIFIER RECEIVER

70-METER

DEMODULATOR

VLA BASEBAND

SYMBOLS COURIER

DECODER

REAL

TIME

DATA 

TO 

JPL

NON-REAL

TIME

SATELLITE

TERMINAL

MONITORING

AND 

CONTROL

MONITORING

AND 

CONTROL

SATELLITE
was instrumental in keeping the signal combining procedure working efficiently even 

the worst summer weather experienced during the Neptune Encounter period.

An item of concern in the initial planning for use of the VLA for Voyager telemet

was the existence of a data gap in the signal output from each of the VLA antenna

The data gap was 1.6 milliseconds in length and occurred approximately 20 times p

second. During the gap period, vital monitoring and “housekeeping” information pass

between the VLA antennas and their remote control center.

Early studies (1982) of the effect of the “gap” on Voyager’s coding scheme indicat

that the error correcting capability of the outer Reed-Solomon code would bridge th

gap and yield error-free performance, comparable to standard performance with perha

0.5 dB loss in threshold level for the combined VGTA output. These estimates we

verified with simulated Voyager data and VGTA hardware and software during tests 

JPL in 1985 and 1986.

The procurement and installation of a fully redundant Earth satellite link with dedica

ed transponders and Earth stations at each site were carried out by a contractor. Followin

the resolution of initial start-up problems and frequency response adjustments at bo

ends of the link, the performance of the satellite link was found to be similar to th

of the microwave link associated with the PCTA.

During 1985, it became clear that the commercial power supplied to the VLA was to

unstable to meet the DSN standards for primary power. Frequent voltage transients an

outages occurred during inclement weather conditions. The operational deficiencies 

the existing commercial power system were overcome by installing two diesel generato

each of 1,400-kW capacity, to provide primary power for the facility. This was follow

by replacement of the deteriorating underground wiring that supplied power to th

antennas out to the limit of the 20-km “Y” arrangement.

While an availability requirement of 80 percent was imposed on the PCTA Uran

Encounter configuration, the favorable experience led to an implicit design goal on th

order of 90 percent for the entire VGTA for the Neptune Encounter. This required se

ting much higher reliability standards for the individual elements of the VLA system

including the twenty-seven individual antennas. In the beginning, it was not at all cle

that thirty antennas (three DSN plus twenty-seven VLA) could be sustained and ope

ated repeatedly with confidence in their reliability, given the diverse geographical an

organizational aspects of the array. Because of these concerns, system reliability was give

special attention throughout the implementation phase, and critical elements, such 

352

Uplink-Downlink: A History of the Deep Space Networ
an online computer and rubidium frequency standard, were provided by the DSN f

use at the VLA.

The majority of the equipment supplied by JPL was installed at the VLA and Goldston

in late 1988. As each major assembly was completed, it was tested at the system lev

before being shipped to VLA or Goldstone for integration with the onsite system

Monthly tests with the VLA and operational training at both sites continued throug

the year. These included demonstration tracks with all antennas on the Voyager spac

craft, where the array data was processed through the end-to-end system and deliver

to the Voyager project for evaluation of its quality.

By May 1989, the VGTA was ready to provide full operational support to the Voyag

mission as the spacecraft began its observatory phase of the mission. It was anticipat

that, from this point on, the resolution in the Voyager images would exceed that of th

best Earth-based observations. These expectations were completely fulfilled by the pe

formances of the VGTA and the PCTA as the mission progressed. Some examples 

the high-quality images that were downlinked at 21.6 kbps from Neptune were show

in Figures 5-7, 5-8, 5-9 of the Voyager section.

All of the careful, pre-Encounter preparations, enhanced by the proficiency of the NRA

and DSN operations personnel at the VLA and Goldstone, paid off handsomely du

ing the Neptune Encounter. Statistics for the period 26 April through 28 Septemb

1989 showed that during the forty Voyager Encounter passes supported in that perio

the VLA signal to the DSN at Goldstone was available 99.959 percent of the time. A

for the full VGTA and PCTA configurations which included the DSN antennas, da

for the same period showed that more than 99 percent of the data transmitted by th

spacecraft, from a distance of 40 AU, was captured by the Earth-based antennas of th

interagency arrays. 

The successful implementation and operation of interagency arrays in Australia and th

United States provided a downlink with the capability of supporting telemetry fro

Neptune at 21.6 kbps for the full view period when the Voyager spacecraft was ov

Goldstone and Canberra (at the standard DSN 90-percent weather confidence leve

Together with the expansion of the 64-meter antennas to 70 meters, interagency arra

ing had enabled a DSN downlink that effectively doubled the science data return fro

the Voyager Neptune Encounter.

35

The Galileo Era: 1986–1996
The X-band Uplink

The arguments that drove the DSN to move from S-band to X-band for operation 

their downlinks were not so compelling for the uplink. While the immediate improv

ment in downlink performance that followed directly from the frequency ratio of S-

X-band was of critical importance to the extension of DSN downlink capability to th

outer planets, there were other means by which the S-band uplink capability could 

extended. Prior to the early 1980s, improvement in uplink performance was achiev

by increasing the power of the DSN S-band transmitters, first from 10 kW to 20 kW

then to 100 kW, and finally to 400 kW. At the same time, the effective radiated pow

in the uplinks was enhanced by the increased gain that resulted from the addition 

new, larger antennas to the Network. Nevertheless, within the DSN Advanced System

Development Section, a small (but very effective) X-band transmitter development pr

gram had been in progress for many years. This program was directed specifically towa

supporting the DSN Planetary Radar program.40 X-band transmitters had also been us

to transmit timing signals from Goldstone to Canberra and Madrid by bouncing th

time synchronization signal off the Moon.41 These transmitters were designed for puls

operation where, although the peak power level was hundreds of kilowatts, the avera

power was on the order of tens of watts. As distinct from planetary radar, planeta

communications required continuous wave (CW) operation at the level of tens of kil

watts. The generation of tens of kilowatts of stable, CW, X-band power, and the pow

dissipation or cooling problems that were associated with it, was a challenging problem

The DSN needed a powerful rationale to embark upon such a task. It first appeared 

1978 with the gathering interest in the search for gravitational waves.

A proposal was made to detect gravitational waves by means of the Doppler signatu

imprinted on a CW, two-way radio link between Earth and a spacecraft crossing th

interplanetary medium.42 The key to success for such an experiment lay in the use 

1) a high frequency for the two-way radio path and 2) extremely high stability for th

frequency of transmission. Together, this amounted to a requirement for a 20-kW, CW

X-band transmitter with a frequency stability of one part in ten raised to the power 

fifteen (1 x 10-15).

Apart from the potential for collaborating in a major scientific discovery, the DSN w

highly motivated to gain the other benefits that were associated with a highly stable X

band uplink. These benefits related principally to improving the quality of the DS

radio metric data used for spacecraft navigation by effectively removing the transmissio

media effects. Improved accuracy of the DSN data would reduce the level of uncertain

354

Uplink-Downlink: A History of the Deep Space Networ
in the orbit determination calculations, on which the spacecraft navigators depended f

knowing the precise location of their spacecraft in interplanetary space.

The DSN undertook a phased development program in 1979 to add an X-band uplin

capability to the Network. In the first phase of this program, an experimental model 

an X-band transmitter and its associated equipment would be built and tested at DS

13, the DSN’s research and development station at Goldstone. In the second phase, 

coherent X-band transponder would be added to an existing spacecraft prior to launc

to be used as an inflight technology demonstration of the end-to-end X-band system

The add-on would not interfere with operation of the spacecraft’s normal S-band uplin

By early 1981, a prototype 20-kW X-band transmitter and a highly stable exciter to dri

it had been developed and were under test in the DSN labs at JPL. Also, arrangemen

were in place to add the X-band uplink to the NASA spacecraft, one of two spacecra

planned for the international Solar Polar mission to be launched in 1985.43 The oth

spacecraft was to be provided by ESA and would eventually be renamed Ulysses.

Despite the cancellation of the NASA spacecraft in 1981, development of the expe

mental X-band uplink continued. At DSS 13, a full-scale ground system, including th

Doppler extractors, X-band to S-band down-converter, and a Block III receiver, was s

up and intensively tested. It was then planned to carry out the inflight X-band tec

nology demonstration with the Galileo and Venus Radar Mapper (later called Magella

spacecraft in 1984, using DSS 13 as the single ground station for the experiment.44

In a 3 June 1982 memo to the Assistant Laboratory Director for Telecommunicatio

and Data Acquisition, the DSN Chief Engineer, Robertson Stevens, drew attention 

the progress that had been made in the development of a stable X-band uplink at DS

13. He also identified the advantages that would accrue from a move to X-band f

operational use in the DSN. Relative to S-band uplinks, Stevens cited, as example

improvements in range and Doppler measurements, immunity to signal distortion b

charged particles along the transmission path, improved telemetry threshold in the tw

way mode of Earth-to-spacecraft communications, and a tenfold improvement in comman

capability. Benefits not directly related to the uplink performance were to be found 

lower cost spacecraft implementation and testing, as well as relief from future radio fr

quency interference problems. 

He concluded by recommending that the operational Network should support the Galil

technology demonstration as a preamble to the initiation of a fully operational X-ban

uplink capability in the DSN.45

35

The Galileo Era: 1986–1996
As a result, the DSN system engineering offices began writing technical requiremen

for the antenna, microwave, receiver/exciter, and transmitter subsystems that would 

necessary to support the addition of an operational X-band uplink capability to the ne

34-m high-efficiency (HEF) antennas, then being planned for implementation in 198

Shortly thereafter, Galileo was postponed to 1986 and Magellan to 1988, and the pri

ilege of carrying out the first X-band uplink inflight demonstration fell to Galileo. 

Frank P. Easterbrook and Joseph P. Brenkle made persuasive arguments for a joi

Gravitational Wave Experiment (GWE) between Galileo (X-band) and Ulysses (S-ban

only), which provided the incentive needed to establish the GWE as a formal scient

ic endeavor,46 as well as a technology demonstration as envisaged by the DSN.

In a carefully worded agreement that reflected the uncertainty of the times with rega

to both budget and X-band operational performance, the DSN committed to impl

menting a 20-kW X-band uplink transmitter and three 34-m HEF antennas to suppo

a technology demonstration which would include Doppler, ranging, two-way radio lo

measurements, and commanding techniques.47 It was believed that particular attentio

to phase stability would achieve a fractional phase stability approaching 5 x 10-15 to pe

mit the detection of gravitational waves. The capability would be available in Canber

(DSS 45) in January 1987, at Goldstone (DSS 15) in July 1987, and in Madrid (DS

65) in January 1988. 

This plan was in process of being implemented when, as a result of the Challenger disa

ter in January 1986, both Galileo and Magellan were postponed to 1989, and Ulysses 

1990. In the aftermath of this affair, the HEF antennas were completed as planned, b

the installation of the X-band uplink was deferred for about three years to meet a new s

of requirements for the 1989 Galileo and Magellan missions. The new dates for the ava

ability of an X-band uplink in the DSN were to be DSS 15 in March 1991, DSS 65 

September 1992, and DSS 15 in January 1993. In the meantime, a method was foun

for controlling the frequency and phase stability of the X-band transmitters to meet th

stringent requirements imposed by the GWE.48 Implementation progressed rapidly. 

In fact, the X-band uplink at DSS 15 was completed and declared operational on 2

January 1990. By the end of the year, fully operational X-band uplinks were comple

at DSS 45 and DSS 65. Tests were run to prepare them for the start of Galileo X

band operations when the high-gain antenna was unfurled in April 1991 for immedia

support of Magellan. Ironically, Galileo never did get to use the X-band uplink becau

of the HGA failure as discussed earlier in this chapter. However, the spectacular su

356

Uplink-Downlink: A History of the Deep Space Networ
cess of the Magellan mission to Venus firmly established the X-band uplink as a pow

erful new DSN capability for Doppler, ranging, commanding, navigation, and rad

science applications. The stringent requirements for X-band frequency stability we

used to great advantage for very precise orbit determination and detection of gravi

anomalies on Venus.

The early planning in 1994 for the new 34-meter beam waveguide antennas had ma

provision for 20-kW X-band transmitters. Budget considerations required these tran

mitters to include major components that were surplus equipment from tracking statio

operated by the Goddard Space Flight Center. Subsequently, it was found that the effe

tive radiated power needed to meet the technical requirements of future flight missio

could be achieved with 4-kW, vis-à-vis 20-kW, transmitters on the new BWG antenna

Furthermore, the overall cost of installing new 4-kW transmitters was estimated to 

about the same as retrofitting the surplus 20-kW transmitters. On these grounds, it w

decided that the new BWG antennas would be implemented with 4-kW X-band tran

mitters and the work was re-directed accordingly.

By mid-1997, the X-band transmitters were complete at all three 34-m BWG ante

nas and, after a short period of operational testing, were put into service a few mont

later. The DSN could now operate two subnets of 34-m antennas with X-band uplin

capability. 

As the Galileo Era drew to a close in 1996, the X-band transmitters of the DSN we

providing uplinks for Mars Global Surveyor, Mars Pathfinder, and Near-Earth Astero

Rendezvous missions. In 1997, the giant Cassini spacecraft depended on X-band uplin

for its mission to Saturn. In 1998, Deep Space 1, the first of the New Millennium m

sions, and the Mars Surveyor Orbiter and Mars Surveyor Lander missions would also u

X-band uplinks. Further into the future, long-term plans within the DSN called for 2

kW X-band transmitters on the 70-m antennas in the first years of the new millennium

In 1997, 20 years had passed since the DSN, motivated by an interest in the search f

gravitational waves, had moved toward X-band for its uplinks. X-band uplinks had becom

a reality; the improvements cited by Stevens in 1982 had all been fully realized, but th

search for gravitational waves using this powerful medium for their detection remain

a challenge for the future. 

35

The Galileo Era: 1986–1996
Block V Receiver

The Block V Receiver (BVR) was an all-digital receiver that had been under develo

ment as the Advanced Receiver and was characterized by high phase stability and extreme

narrow tracking loop bandwidths, both highly desirable features for the Galileo and oth

weak downlink applications.49

The BVR first appeared for initial testing with the Galileo downlink at Goldstone 

February 1994. As a result of these tests, some design modifications were made. In 

further series of tests at the end of the year, the BVR successfully demonstrated its ab

ity to track the weak Galileo downlink at all modulation settings, including the ful

suppressed carrier mode. A telemetry data stream was flowed to JPL, and Doppler da

were extracted and delivered to the Metric Data assembly. Repeated tests with the Galil

downlink in early 1995 confirmed the BVR performance under full operational cond

tions and showed excellent agreement with the performance predicted by theory.

Compared to the existing DSN Block IV receiver, the BVR showed greatly reduc

high-frequency noise characteristics; it was virtually free of cycle slips even when th

antennas were pointed close to the Sun, and noise in the Doppler data was reduced b

at least a factor of three.

The role of the BVR in the development of the DSN Galileo Telemetry Subsystem (DGT

is described later. However, the new capabilities brought to the DSN downlinks by th

BVR were not limited to its Galileo application. Its ability to track downlinks in the su

pressed carrier mode; the extremely narrow bandwidth (about 0.1 Hz) of its carrier trackin

loop; rapid, automatic signal acquisition; and great stability and versatility made it a

obvious replacement for the older Block III and Block IV receivers throughout the Networ

The time was propitious for the DSN to make such changes. The number of antenn

in the Network had more than doubled in recent years, as had the number of simult

neous downlinks now handled by the DSN at each Complex. A separate receiver w

necessary for each link, and the existing analog-based Block IV receivers were near th

end of their lifespan. New receivers were needed, and the high-performance, multipl

function capability of the all-digital BVRs made them a logical choice for the new er

The 70-m antennas were equipped with BVRs in May 1995, followed by the 34-m HE

and 34-m BWG antennas a year later. A few of the old Block III and Block IV receive

were retained for use with the remaining SDA/SSA units on the 34-m STDN antenn

and the 26-m Low-Earth Orbiter antennas.

358

Uplink-Downlink: A History of the Deep Space Networ
The BVR not only performed residual carrier tracking, which was the only functio

performed by the Block III and Block IV receivers, but it also performed suppress

carrier tracking and carried out subcarrier and symbol demodulation functions. It ther

fore replaced not only the former Block III and IV receivers, but the former SDA/SS

and DSA units as well. In addition, it carried out the functions of signal estimatio

Doppler extraction and IF signal distribution, thereby replacing the signal precision pow

monitors, Doppler extractors and IF distribution equipment that had been an integr

part of the Mark IVA DSN.

The BVR accepted an S-band or X-band signal from a low-noise amplifier on the ante

na to which it was assigned by the station controllers and, after performing the functio

described above, distributed the following outputs for subsequent data processing:

1. two symbol streams to the assigned telemetry channel assemblies (TCAs) for deco

ing, frame synchronization, and telemetry data delivery;

2. two baseband outputs to the baseband assemblies (BBA) for combining with sim

ilar signals from other antennas;

3. two open-loop IF signals to other subsystems, such as radio science and VLBI, f

special signal spectrum processing; and

4. two range-modulated signals to the Sequential Ranging Assembly (SRA) for ran

ing measurements.

Local Area Networks provided for communication and control between the BVR an

other subsystems, and between the BVR and station controllers at the Link (LMC) 

Complex (CMC) Monitor and Control level.

The DSN Galileo Telemetry (DGT) Subsystem

As it gradually became apparent that the Galileo HGA problem might not be correc

ed in time to save the mission as originally designed, attention began to turn towar

viable options for continuing the mission in a modified form, using the spacecraft low

gain antenna (LGA).

In October 1991, the Telecommunications and Data Acquisition (TDA) Office at JP

chartered a thirty-day study to identify a set of options for improving the telemetry pe

formance of the Galileo downlink at Jupiter, using the LGA, in the event that the HG

35

The Galileo Era: 1986–1996
could not be recovered. The study team was led by Leslie J. Deutsch, Manager 

Technology Development in the TDA Office. 

The jobs of tuba player for a Dixieland jazz band and organist for a choir, church, an

synagogue might seem unlikely roles for the mathematician most responsible for lea

ing the DSN effort to recover the Galileo mission to Jupiter. However, all three rol

were at one time played by Dr. Leslie J. Deutsch. Born and raised in Los Angele

California, “Les” Deutsch spent much of his early professional life developing electro

ic music technology for his father’s Deutsch Research Laboratories. After earning a doctora

in mathematics from the California Institute of Technology in 1980, Deutsch join

JPL in the Communications Systems Research Section, the section originally led b

Walter K. Victor twenty years earlier. Deutsch became manager in 1986.

In 1989, he took charge of the Technology Development program in the Tracking an

Data Acquisition Office, and it was while there that he brought the considerable resourc

of that group to focus on the Galileo problem. The full scope of the research carri

out under that program is discussed separately in chapter 6. 

A pleasant man of medium build, Deutsch always appeared to be busy. He was as mu

at ease discussing an abstruse mathematical representation of some physical problem 

the DSN as he was executing a complex musical phrase on the pipe organ or tearin

off a tuba riff in a jazz band.

In an interesting sidelight to his involvement with Galileo, Deutsch was invited to accom

pany a small party from NASA and JPL to Padua, Italy, in 1997 to participate in 

“Three Galileos” conference. Sponsored jointly by the University of Padua, the Germa

and Italian space agencies, and NASA, the conference honored “Galileo, the Man

“Galileo, the Telescope,” and “Galileo, the Spacecraft.” Deutsch contributed a technic

paper50 on the Galileo telemetry recovery effort. He was also honored with an invit

tion to present an organ recital in the Basilica of St. Anthony at Padua that featur

music of Galileo’s time. Dr. Deutsch continued to manage the program of technolo

development for the DSN until 1998, when he transferred to another area of JPL 

study new technologies for planetary spacecraft.

Deutsch began by establishing a set of assumptions on which the team would base 

considerations. Because of the HGA problem, all telemetry was being transmitted fro

the spacecraft on an S-band carrier through the LGA. The design of the spacecraft pr

cluded the transmission of X-band telemetry through the LGA. If nothing was done 

improve the S-band downlink performance by the time the spacecraft arrived at Jupit

360

Uplink-Downlink: A History of the Deep Space Networ
in December 1995, the telemetry data rate would be only 10 bits per second, compar

to the rate of 134,000 bits per second that had been designed into the original X-ban

mission.

The question facing the team was, “What could be done by making changes to th

DSN or the spacecraft, or both, to improve this situation in the time available, and ho

much would it cost?”

Because the period of the study coincided with the Galileo Encounter with astero

Gaspra, technical participation from the spacecraft and mission design areas was lim

ed. Deutsch presented the team’s report on 5 November 1991.

Out of the eight options that were identified, the following four were recommended f

further evaluation: 

Arraying Antennas

Increase the effective aperture area of the DSN antennas by building new ones 

arraying existing DSN antennas with large, non-DSN antennas such as were the

in operation in Australia, Japan, Germany, and Russia. In addition, the S-band pe

formance of the existing 70-m antennas could be improved by installing spec

low-noise feeds called “ultra-cones.” 

Compression

Use data compression techniques on the spacecraft to increase the effective telemet

rate by reducing the number of data bits that needed to be transmitted for each imag

Coding

Improve downlink capability at low data rates by adding more advanced coding 

the existing coded telemetry data stream. This would require inflight reprogram

ming of the spacecraft computers. 

Modulation

Increase the effective power received by the ground antennas by changing the mo

ulation index at the spacecraft transmitter to fully suppress the S-band carrier. Th

36

The Galileo Era: 1986–1996
would have the effect of putting all the transmitted power into the subcarrier sid

bands that carried the information content of the downlink.

Estimates of the performance gain, cost, and uncertainty associated with each optio

were made and evaluated. The study concluded by emphasizing the urgent need for th

TDA and the Flight Project Office (FPO) to jointly develop a workable plan to impl

ment the necessary changes in the spacecraft and in the DSN in the limited time availab

The positive results of the largely TDA-driven, thirty-day Galileo Options study, alon

with its emphasis on the need for timely action, led to the chartering of a further stud

which would involve both TDA and the Flight Projects Office (FPO). It was to 

called the Galileo S-band Mission Study and would run from 9 December 1991 throug

2 March 1992. The co-leaders of the study group would be Leslie J. Deutsch, repr

senting TDA, and John C. Marr, Manager of JPL’s Flight Command and Data Manageme

Systems Section, representing FPO.

The objectives of that study were to

• assimilate and verify the information from the previous TDA Galileo Options Stud

• solicit additional ideas and assess their performance benefit and feasibility;

• create a conceptual design for the end-to-end telemetry system for the Galileo S-ban

mission;

• generate a rough cost estimate for this design for submission to the program offic

at NASA Headquarters which were responsible for funding TDA (Code O) and FP

(Code S) in time for the Fiscal Year 1994 budget cycle; and

• make specific recommendations for the implementation of an end-to-end data syste

and hand these over to the organizations that would perform the work.

Whereas the TDA study had addressed only the high-rate science telemetry downlin

this study included real-time, low-rate science and spacecraft engineering data, uplin

command and radio metric data, and navigation data. It also stipulated that no improv

ments to the downlink would be made until the important Probe science data had bee

successfully returned to Earth using the existing downlink capability.

362

Uplink-Downlink: A History of the Deep Space Networ
The basic conclusion of the study was that a viable Galileo S-band mission was inde

feasible, based on a design that could meet a somewhat reduced, but still very accep

able, set of science objectives. Such a design could be implemented in time for the sta

of the Galileo orbital mission, and the total cost to NASA would be about 75 millio

dollars spread over seven years.

The results of the study were presented at NASA Headquarters on 20 March 1992 b

Deutsch and Marr, supported by the Galileo Project Manager, William J. O’Neil, an

the Galileo Project Scientist, Torrence V. Johnson.51

O’Neil came straight to the point. There was no way of knowing whether the HG

would eventually be deployed, he said, and NASA should therefore prepare to comple

the Galileo mission with the spacecraft LGA. He said that a key design feature of th

new LGA mission would limit the data return from the tape recorder to one full tap

recorder load for each of the ten targeted satellite encounters. That feature, coupled wi

the proposed enhancement of the downlink by additions to the spacecraft and DSN

gave reason for great optimism that a worthwhile scientific endeavor could still be su

cessfully accomplished. 

In addressing the mission science objectives, Johnson demonstrated that the propose

LGA mission would, in effect, yield 70 percent of the science return expected fro

the original HGA mission. That new science, he said, would represent a major advan

beyond the current level of Jupiter knowledge based on the results of the Voyag

mission.

Marr described the reprogramming changes that would have to be made in the spacecra

computers to add the new data compression and encoding algorithms; he also described t

costs, risks, and implication of these changes in data format on Galileo mission operation

The four options recommended for enhancement of the downlink by the DSN we

essentially a refined version of those that had originated in Deutsch’s original stud

Suppressed carrier modulation would yield 3.3 dB improvement; advanced coding, 1

dB; ultracones for 70-m antennas, 1.6 dB; and antenna arraying, 0-4 dB depending o

which antennas were used. Together with the spacecraft modifications, these enhanc

ments would provide a capability in the DSN to return one full load of tape-record

data after each satellite encounter. They also satisfied the project requirements for recei

ing continuous engineering data and low-rate science data. The options for arrayin

antennas were not limited in this presentation to just the DSN. They included the co

36

The Galileo Era: 1986–1996
of adding the large antennas at Parkes (Australia), Bonn (Germany), and Usuda (Japa

to the DSN arrays.

Following the presentations, action items to study three alternative approaches were assigne

and the JPL team returned to Pasadena to prepare for a final decision meeting set f

10 April 1991.

The three alternative approaches related to when and how the various arraying optio

would be implemented in the DSN. This decision largely affected funding profile issu

that were of paramount importance in the NASA Headquarters view of the LGA missio

The final meeting was attended by the newly appointed JPL Director, Edward C

Stone, in addition to the NASA Associate Administrators for Space Communicatio

and Space Science.

While the previous meeting emphasized the technical aspects of the LGA mission an

addressed the costs in a rather general way, this meeting concentrated specifically o

costs and the time rate of expenditure that would be incurred by the three alternati

approaches previously identified. Since support of the LGA mission would require 

much 70-m antenna time at the expense of other ongoing and future missions, the iss

of DSN loading was also included in the DSN presentation.

The major cost drivers for the DSN were known to be the decoder and decompresso

the ultracones for the 70-m antennas, the signal combiners, communication links betwee

antenna sites, and the cost of renting time on whichever of the non-DSN antenn

would be chosen for arraying. Except for the latter, each of the costs was well unde

stood, easily identifiable, and bounded. The arraying costs were not.

At a breakfast meeting on the morning of the presentations, the new JPL director express

concern over the uncertainty associated with arraying costs and the rather overwhelm

ing number of options available to choose from. His concern prompted Deutsch 

propose a last-minute option that he had budgeted out during an impromptu lunchtim

session in a vacant office at NASA Headquarters. The “Deutsch” proposal limited 

arraying operations to the Canberra site. The Australian antenna at Parkes would be th

only non-DSN antenna used for arraying, and DSS 43 would be the only antenna f

ted with an ultracone. This approach offered a more manageable proposal on which 

base a decision and was included as part of the total DSN presentation. The total DSN

related cost was estimated to be 38.3 million dollars spread over the six fiscal years 199

through 1997, with the major cost impact in 1994. The spacecraft and mission oper

364

Uplink-Downlink: A History of the Deep Space Networ
tions costs were 31.8 million dollars over the same period. This strategy was successf

and was accepted as the way to recover the science data from Jupiter. Taken togeth

the spacecraft and ground system proposals would provide 70 percent of the origin

science data value at 1 percent of the original data rate for an overall cost increase 

less than 5 percent. 

The Galileo LGA mission as eventually approved by NASA satisfied most of the pro

ect requirements for real-time data and playback data return. It also provided for th

new spacecraft capability but delayed the DSN enhancements until late 1996. It inclu

ed DSN arraying centered on Canberra, as proposed by Deutsch. Software “hooks” we

to be inserted in the design for the possible later inclusion of arraying with Parkes 

Usuda, if funds could be identified.

The conceptual arrangement of telemetry proposed for DSN support of the Galileo LG

Mission is depicted in Figure 5-31.

Three types of receive antennas were to be used. These included the DSN 70-m ante

nas and the DSN 34-m antennas, with the non-DSN antenna at Parkes, Australia, 

an option. Each antenna was to be equipped with a low-noise amplifier (LNA). Th

DSN 70-m antennas and the Parkes antenna would be equipped with ultracones an

low-noise maser amplifiers, the others with cooled High Electron Mobility Transist

(HEMPT) amplifiers. 

36

The Galileo Era: 1986–1996

Figure 5-31. The concept of DSN telemetry for the Galileo LGA mission.

DSN 70M

DSN 34M

OTHER

APERTURES

LNA’S/

RECEIVERS

LNA’S/

RECEIVERS

LNA’S/

RECEIVERS

TAPE

TAPE

TAPE

REAL TIME

COMBINER

DECODE DECOMPRESS

DEMOD/

DETECT

REAL

TIME

COMM

LINKS
The LNAs were to be followed by receivers that would translate the incoming S-ban

signals to a lower frequency, filter out the uninteresting parts of the bandwidth, an

digitize the resulting signal. The digital signals would be recorded on tape and sent 

a central site for combining with the signals from the other antennas. There was al

an option to send the digitized signal to the central site in real time.

At the central site, the signals from each antenna would be aligned with one anoth

and combined (summed). The alignment would be accomplished by looking for the si

nature of the packet synchronization markers in the signals. The summed signal wou

then be demodulated. During much of the mission, there would not be enough sign

strength to perform any demodulation before this summation. In some cases, data cou

be lost in the aligning process. When this happened, post-processing of the tape-recor

ed signals would be used to recover the data.

Following demodulation, the composite signal would be decoded in two stages. Fir

the effective (14, 1/4) convolutional code would be decoded. Then the Reed-Solomo

code would be decoded. Finally, the effects of the two spacecraft compression algorithm

would be undone in two decompressors. Subsequent processing of the science data wou

be performed by the Galileo Mission operations organization and the Science Teams

From a technical point of view, the Galileo LGA Mission represented a remarkab

episode of conceptual design in the areas of spacecraft data systems, planetary missio

design, and DSN downlink engineering. However, before these concepts could becom

a reality, they had to be funded and implemented. While the NASA Headquarters pe

ple went off to wrestle with the funding problem on the short time scale required, th

JPL people returned to Pasadena to initiate the implementation tasks.

Although we are only concerned here with the DSN effort, it needs to be said for th

record that this evolution was an intensively interactive process. A satisfactory end resu

could only have been achieved by keeping all three elements—spacecraft, DSN, an

mission operations—focused on the end-to-end performance of the downlink, while th

implementation tasks proceeded as separate entities.

The task of implementing the DSN portion of the Galileo LGA mission was assigned 

Joseph I. Statman, whose previous experience with developing the Big Viterbi Decoder f

the original Galileo mission in 1989 was reported earlier. As Task Implementation Manag

Statman became responsible for transforming the conceptual ideas into hardware and so

ware and installing and testing this equipment at the three DSN sites around the globe

This task was to be accomplished within the cost estimates that had been presented to (an

366

Uplink-Downlink: A History of the Deep Space Networ
accepted by) NASA, and completed in time to support multiple Galileo Encounters wi

the satellites of Jupiter in less than forty-eight months. Although most of the technolo

was available, none of it had found practical application in this way, or on this scale, befor

Some arraying technology had been used in the earlier Voyager encounters with Uran

and Neptune, and better techniques had been the subject of continuous study since then

It had, however, been centered at Goldstone and had not involved intercontinental arra

ing between Goldstone and Canberra. The application of coding to enhance the performan

of telemetry downlinks was well established in the DSN, and an advanced version of co

catenated, convolutional coding had been added to the Galileo spacecraft downlink pri

to launch.54 This was intended for use at very high data rates (134 kbps) during the 

Encounter on the original X-band mission. Because it could not operate at the low da

rates (10–100 bps) which would be typical of the LGA mission, it was of no further us

Nevertheless, the studies that had gone into developing that coding system were to 

extended and applied in a new way to the LGA mission.55

Under the guidance of Statman, a comprehensive set of system and subsystem requir

ments and a cost breakdown for the DSN Galileo Telemetry (DGT) Subsystem, as 

came to be called, was prepared and presented to a DSN Review Board for approval o

3 December 1992. Five days later, Galileo made its second and final close flyby of Ear

and was on a direct path to Jupiter, just three years away. There was no time to lose

In the course of transition from conceptual form to physical form, the DGT had be

somewhat modified. Decompression of the received data function had become a Galil

mission operations function, and the arraying function had been limited to the one 7

m and three 34-m DSN antennas at Canberra. The combiner at CDSCC, however, w

to make provision for combining the signals from up to seven antennas. This would pe

mit a digitized signal from the DSN 70-m antenna at Goldstone to be added to th

Canberra array to create real-time intercontinental arraying during Goldstone-Canber

overlapping view periods. The use of non-DSN antennas was not considered in this revie

The form in which the DGT was implemented at CDSCC is shown in Figure 5-32

Although it was not considered part of the DGT, the Block V Receiver (BVR), show

in Figure 5-32, was an integral part of the DSN configuration for Galileo. Its prima

purpose was to track the fully suppressed carrier downlink from a single 70-m antenn

to extract telemetry and the two-way Doppler data essential for radiometric-based na

igation of the Galileo spacecraft. When multiple-antenna arraying was used, the BV

provided Doppler data only and the DGT provided telemetry as described above. I

implementation proceeded in parallel with, but a year ahead of, the DGT.

36

The Galileo Era: 1986–1996
368

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-32. Functional diagram of the DSN Galileo Telemetry Subsystem for the Canberra Deep Space Communications Complex. The S-band signals from each of the antennas were first stepped down by 300 MHz to feed the Full Spectrum Recorders (FSR). Afterrecording, the separate digitized signals were summed in a Full Spectrum Combiner (FSC) and delivered to a software receiver, wherethe detection and demodulation functions were carried out in a Buffered Telemetry Demodulator (BTD).56 The complex decoding operation on the inner and outer codes was performed by a special Feedback Concatenated Decoder (FCD)57 that delivered a decoded data

stream to the ground communications equipment for formatting and transmission to JPL via the GCF. A system controller performed all

the configuration and data management tasks via several local area networks. The arrangement at Goldstone was similar, except thatthere was no ultracone and no Full Spectrum Recorder. At Madrid, the arrangement was simpler still, consisting only of the decoderand system controller

70M

34M STD

34M HEF

34M BWG

ULTRA 

CONE

VLBI

D/C

VLBI

D/C

FULL SPECTRUM

RECORDER

BLOCK 5

RECEIVER

FULL SPECTRUM

RECORDER

FULL SPECTRUM

RECORDER

FULL SPECTRUM

RECORDER

FULL 

SPECTRUM

COMBINER

SOFTWARE

DECODER

RECEIVER

DSS-14

GCF

TO JPL

SUBSYSTEM CONTROLLER

VLBI

D/C

VLBI

D/C

EXISTING

EQUIPMENT
Repeated tests with the Galileo downlink in early 1995 confirmed the BVR perform

ance under full operational conditions and it was accepted for future Galileo S-ban

mission support. 

By May 1995, BVRs had been installed at all Complexes and soon demonstrated the

ability to track the Galileo downlink in the suppressed carrier mode, deliver telemetr

and extract Doppler data. 

In September 1995, based on these impressive results, the Galileo downlink was fina

ly switched to the suppressed carrier mode that, supported with the BVR, would becom

the standard mode of operation for the rest of the mission. Less than three months lat

Galileo arrived at Jupiter, relying on the BVR to track its low-powered S-band dow

link and recover the most important data of the entire mission, the Probe entry scien

data. Over the next several months, the BVR lived up to everyone’s expectations, an

in recovering all of the Probe playback data, it allowed the Galileo project to accom

plish its primary mission objective.

The tests conducted at Goldstone in early 1994 to demonstrate the BVR had also bee

used to demonstrate the proposed full-spectrum recording and full spectrum combinin

techniques58 using prototypes of each of these elements of the DGT. The Galileo dow

link signals from DSS 14 and DSS 15 were recorded simultaneously by the prototyp

FSR and were later combined with the prototype FSC.59 The results were well with

the predicted performance limits. Later experiments would verify similar performance 

combining the downlinks from the intercontinental array of DSS 43 with DSS 14.

Over the course of the following two years, the operational versions of these units we

built, installed, and tested at the Complexes. Since arraying was to be used only at Canberr

that was the only site where a full-spectrum combiner was installed. Also during this pe

od, an ultra-low-noise, receive-only feed system (ultra-cone) was added to the Canber

70-m antenna to reduce the S-band system noise temperature from its normal value 

15.6 kelvin (K) to 12.5 K. By reducing still further the noise on the downlink, this add

tion enhanced the performance of the downlink and increased the rate at which it cou

return data from the spacecraft. The DGT was rapidly taking real form and substance

Although the DSN had received approval (and funding) from NASA Headquarters f

the use of multiple-antenna arraying techniques to support the Galileo LGA mission, th

support was limited to DSN antennas only. As design studies matured, however, it becam

evident that, even with the already-approved downlink enhancements in the DSN, th

Galileo science data return would be especially low during the six-month period when th

36

The Galileo Era: 1986–1996
spacecraft was farthest from Earth, November 1996 through April 1997. This was the pe

od when four of the ten satellite encounters would occur. Galileo and DSN concern wi

this situation in March 1994 led the TDA Executive Committee to recommend that th

DSN array configuration planned for Canberra be augmented with the 64-m antenna 

the Australian radio telescope at Parkes. The cost of making the necessary modificatio

to the DSN, making additions to the Parkes antenna, and renting time on this antenn

was estimated at 4.3 million dollars. This would be met by funds transferred from th

Galileo project. The estimated enhancement in data return was about 10 percent. 

NASA approval was quickly followed by an Australian agreement to participate in the Galil

LGA mission, and the DSN began work on the changes needed to add Parkes to the Canber

array. Working arrangements with Parkes were quickly reestablished based on the agreemen

that had been made for Parkes support of the Voyager mission a few years earlier.

The DGT at Canberra supported the 70-m antenna, plus three 34-m antennas at CDSCC

plus the 64-m antenna at Parkes, in addition to the 70-m antenna at Goldstone whe

ever overlapping view periods permitted.

While DSN engineers had been focused on implementing the BVR and the DGT 

the Network, the Galileo project focused on the changes that were required in the spac

craft to make the end-to-end downlink work. At the same time, the project had to car

the mission forward to the point at which the new flight software could be transmitt

to the spacecraft. This point was reached on 13 May 1996, when the DSN began rad

ating a continuous series of commands to load the spacecraft computers with the ne

Phase II flight software. The continuous sequence was completed without incident nin

days later on 22 May, and the spacecraft was enabled to begin operating in the ne

mode the following morning.

By that time the DGT, including the FCD decoder, was in place at all three Complex

and ready to handle the new concatenated convolutional (14, 1/4) coded downlink 

all bit rates in the suppressed carrier mode. 

The Ganymede Encounter on 28 June 1996 was the first critical test of the new flight so

ware and the DGT ability to process it. Since it was not yet ready for full arraying, the DS

used single 70-m antennas to return the Encounter data. As the tape recorder playback da

began to arrive over the new downlink for the first time, the Galileo project manager declar

the images returned from the Ganymede Encounter to be “absolutely stunning” and a tri

ute to everyone involved in meeting the challenges of the LGA mission.60 The end-to-en

370

Uplink-Downlink: A History of the Deep Space Networ
design of the new downlink had been proven in critical flight operations conditions, and t

initial optimism for a successful conclusion to the Galileo Mission was fully vindicated.

The Callisto Encounter in November 1996 was the first occasion on which multiple ante

na intercontinental arraying at CDSCC was used in critical real-time operations. The fu

DSN array capability, augmented with the Parkes antenna, allowed the Galileo spacecra

data rate to be raised from 40 bps to 120 bps during overlap periods. This Encount

too, was extremely successful and demonstrated the full operational capacity of the DG

Based on the performance of the DGT in supporting the Callisto Encounter, the ens

ing recorded data playback, and confidence in the DSN ability to deal with the increas

operational complexity of full array operations, the DGT and associated array mode w

designated as the standard configuration for all subsequent Galileo operations in the DSN

The operational complexities and remarkable downlink performance resulting from this arrang

ment throughout the rest of the Galileo mission were discussed earlier in this chapter.

Beam Waveguide Antennas

The weekly edition of “Significant Events in the DSN” for 29 August 1997 reporte

“After successfully completing an extended series of mission verification tests on the X

band uplink and downlink capability, the 34-m beam waveguide antenna in Canber

(DSS 34), began operational tracking support this week. This antenna will now be ava

able to provide support [to] such missions as NEAR, Mars Global Surveyor, Mars Pathfind

and Cassini, in addition to continuing support for the Galileo array.” It further repor

ed, “System performance testing began on schedule this week on the new 34-m bea

waveguide antenna in Madrid (DSS 54). This will be followed by mission verificatio

testing prior to the antenna being scheduled for operational tracking support on 1 Octob

1997.” And so they were. 

Together with DSS 24 at Goldstone, which had been completed in February of 199

the completion of DSS 34 and DSS 54 gave the DSN a full subnet of three 34-m bea

waveguide (BWG) antennas, which represented a most significant increase in uplink an

downlink capability. 

Based on the successful design of the existing 34-m high-efficiency (HEF) antennas, th

new BWG antennas now extended the existing DSN uplink and downlink capabiliti

on S-band and X-band to include Ka-band (32 GHz). 

37

The Galileo Era: 1986–1996
The design of the 34-m BWG antennas embodied the most advanced principles of ante

na and microwave design. It also represented the culmination of nearly ten years of DS

engineering, research, and development, which began with a JPL report on Ka-band dow

link capability for Deep Space Communications by Joel G. Smith in December 1986.6

In advocating the extension of DSN downlink, and ultimately uplink, capability to K

band, Smith argued that, just as the move from L-band (0.96 GHz) to S-band (2

GHz) had offered a possible increase in performance by a factor of 5.74 (7.6 dB), an

the move from S-band to X band (8.4 GHz) a further increase of 13.5 (11.3 dB), th

move from X-band to Ka-band (32 GHz) offered a potential increase in performan

of 11.6 dB. These improvements were based on the theory that the capacity of a rad

link between two well-aimed antennas is roughly proportional to the square of the ope

ating frequency. In practice, the actual realizable gain is reduced by effects in the propagatin

media and losses in the various physical components of the link.

However, these latter effects could be controlled more easily at higher frequencies whe

microwave components, particularly the surface area of the antenna itself, could be sma

er, stiffer, and mechanically more precise. Furthermore, measurements had shown th

degradation of downlink reception at Ka-band, due to weather effects, was not as seve

as had previously been thought. 

Based on these considerations, Smith proposed a course of action which would culm

nate in an operational Ka-band downlink capability in the DSN by 1995. It began wi

the development of a new research and development antenna at Goldstone to “veri

the various approaches to be used in upgrading the existing 34-m and 64-m/70-m ante

nas to good efficiency at Ka-band.” 

As Smith pointed out, there were other reasons, independent of the Ka-band decisio

for building a new research and development antenna at Goldstone, but there was 

strong synergism between the two.

In a companion paper,62 Smith laid out all of the arguments for a new antenna, inclu

ing those related to Ka-band, and proposed a specific design based on the existing HE

antennas but modified to incorporate new beam waveguide technology for the transpo

of microwave energy at low level (receiving) or high level (transmitting) between th

antenna and the receiving or transmitting devices.

At that time, 1986, the beam waveguide concept had been around for several years, b

it had not been employed in the design of any DSN antennas. It had, however, bee

372

Uplink-Downlink: A History of the Deep Space Networ
used recently in the design of several major non-DSN antennas, most notably the 6

m antenna at Usuda, Japan, and the 45-m radio astronomy antenna at Nobeyama, Japa

R. C. Clauss had made an evaluation of these installations and became a strong adv

cate for the new technology.63

The supporting arguments included significant simplification in the design of high-pow

water-cooled transmitters and low-noise cryogenic amplifiers, improved accessibility f

maintenance and adjustment, and avoidance of performance degradation associated wi

the accumulation of rain and moisture on the feedhorn cover. Beam waveguide tec

nology allowed these systems to be located in a fixed, nonrotating area beneath th

antenna azimuth bearing. As a result, the long bundles of power and signal cables an

cryogenic gas lines that were required on the existing antennas could be replaced wi

short, fixed, nonflexing connections. Better frequency stability, higher reliability, an

improved performance could be expected.

A beam waveguide system is shown in conceptual form in Figure 5-33.

The flat reflectors were used to redirect the beam; the curved reflectors were used to ref

cus the beam. As the antenna rotated in elevation, or azimuth, the transmitting or receivin

beam of microwave energy was constrained to the beam waveguide path by the action 

the reflecting and refocusing surfaces. The various reflectors were enclosed by a large pr

tective tube or shroud along the beam waveguide path. Although this tube was a high

visible element of a BWG antenna, it played no significant part in the beam wavegui

transmission process.

Over the next two years, 1989 and 1990, a design for a new BWG research and deve

opment antenna at DSS 13 was completed; funding was obtained; and construction 

the new antenna commenced.64 It would be located about 300 feet south of the exis

ing 26-m antenna at the Venus site at Goldstone, and it was scheduled for completio

in mid-1990. It was intended to serve as the prototype for a whole new generation 

DSN antennas using the new BWG-type of antenna feed system.

The mechanical and microwave optical components in the BWG path are visible in th

diagram of the completed DSS 13 BWG antenna shown in Figure 5-34. 

From July 1990 through January 1991, the new BWG antenna was tested as part of 

post-construction performance evaluation. Antenna efficiency (gain) and pointing pe

formance measurements at X-band and Ka-band were carried out using unique portab

test packages installed at either of the two focal points, F1 and F3. Celestial radio sourc

37

The Galileo Era: 1986–1996
of known flux density were used in the calibration process. The values of peak efficien

of 72.38 and 44.89 percent, at X-band and Ka-band respectively, measured at the bea

waveguide focus, met the functional requirements for antenna performance and agre

well with the predicted design values.65 Further testing followed, as frequency stabili

noise temperature, and the G/T ratio were evaluated and optimized. 

Because system noise temperature is a critical parameter in deep space communicatio

systems, the system noise temperature of the new antenna was of special concern. 

the early tests, the system noise temperature was found to be higher than expected d

to the spill-over losses of the BWG mirrors having a greater effect than previously thought

374

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-33. Beam waveguide antenna in conceptual form. In this diagram, Reflectors 4 a

3, mounted along the elevation axis of rotation, brought the beam from the subreflector on t

main antenna down to the alidade structure. There, Reflectors 2 and 1, along the vertical ax

brought the beam to a stationary equipment room below the alidade that housed the transmitti

and receiving equipment. 

SUBREFLECTOR

PLANE REFLECTOR 4

ELEVATION AXIS

AZIMUTH AXIS

REFLECTOR 1

(CURVED OR FLAT)

REFLECTOR 2

(CURVED OR FLAT)

CURVED 

REFLECTOR 3

MAIN REFLECTOR 

VIRTUAL

FOCUS

FEED HORN

FEED NETWORK
New feedhorns were designed and tested and new methods for determining noise tem

perature in beam waveguide systems were developed.67

While the construction and testing of the prototype antenna at DSS 13 was in progre

submissions for funding for a fully operational version of a BWG at Goldstone (DS

24) were being made. At this time, the Galileo mission to Jupiter was progressing no

mally and the high-gain antenna had not been deployed. The planned close flyby of 

in December 1995 over Goldstone demanded the full X-band support of the 70-m an

HEF antennas at Goldstone, leaving little or no resources for other flight projects. Usin

this as justification, further funding for two more BWG antennas was requested fro

NASA Headquarters and, at the expense of some institutional compromises, was awar

ed. Now there was funding for a cluster of three BWG antennas at Goldstone, DSS 2

DSS 25, and DSS 26. These were placed on contract with an American constructio

37

The Galileo Era: 1986–1996

Figure 5-34. DSS 13 beam waveguide antenna.

TRIPOD

SHAPED-SURFACE

SUBREFLECTOR

34-m SHAPEDSURFACE

REFLECTOR

F1

CENTERLINE

BEAM

WAVEGUIDE

AZIMUTH

TRACK

PEDESTAL

ROOM

MICROWAVE

TEST

PACKAGE

F3

F2

SHROUD FOR

A BYPASS

BEAM-WAVEGUIDE

SYSTEM

REAR VIEW
376

Uplink-Downlink: A History of the Deep Space Networ

company, TIW Systems, Inc. All three antennas would be located in the Apollo Vall

at Goldstone, and work began immediately.

Figure 5-35. Design for operational 34-meter beam waveguide antenna. In the operational ve

sion of the 34-m beam waveguide antenna, the alternative bypass microwave system was eliminat

and the alidade structure was strengthened to add stiffness and to accommodate the addition

drive and ancillary services.

SIDE ELEVATION
By the time construction began, the original design for the DSS 24 antenna had be

modified to incorporate many of the lessons learned from the DSS 13 experience and th

intensive program of performance measurements that had been conducted on that ante

na. In particular, the antenna structure had been modified to improve its “gravity performanc

by controlling the antenna distortion for best fit to the ideal parabolic shape, as the ante

na moved through the full range of elevation angles. Other improvements related to th

azimuth cable wrap-up and to the substitution of nonmechanical “RF Choke” bearin

for the mechanical tube bearings used at the rotating junctions of the waveguide shrou

Also, the four large (30-inch diameter) wheels which supported the alidade structure o

the azimuth track had been “surface hardened” to improve wearability, based on oper

tional experience with the existing HEF antennas. After a short period of use, these whee

cracked and had to be replaced with “through hardened” wheels to stand up to the loa

and wear induced by continuous use under operational conditions. The design features 

the operational version of the DSN 34-m BWG antenna are illustrated in Figure 5-35

Construction of DSS 24 began in February 1992 with the blasting of a large hole, 3

feet deep and 60 feet in diameter, into solid bedrock to accommodate the pedestal roo

with its 24-ft- high ceiling. Because this was the first antenna to be built, it reveal

the presence of several unsuspected problems in design and planning and, acting som

what as a pathfinder for the others, was not completed until May 1994.

Microwave performance testing of the new antenna was carried out during the summ

of 1994 using the same techniques that had been employed at DSS 13. Antenna ef

ciency, pointing calibrations, and system noise temperature were all included at S-ban

X-band, and Ka-band.68 In addition, microwave holography was used to adjust the refle

tor panels on the main antenna for optimum efficiency. 

The values for gain and efficiency obtained from these tests are tabulated below:

DSS 24 Peak Gains and Efficiencies

Band, Frequency (GHz) Gain (dBi) Efficiency (percent)

S, 2.295 56.79 71.50

X, 8.45 68.09 71.10

Ka, 32.00 78.70 57.02

The results of these measurements confirmed the soundness of the basic design and th

improvements that had accrued from the modifications mentioned above. 

37

The Galileo Era: 1986–1996
Experience gained from the DSS 24 task enabled the remaining two antennas to 

built in a parallel fashion to save time. They were completed in July and August 199

respectively, about 18 months after construction started in 1994.

Unlike DSS 13, which was built for deep space communications research and develo

ment purposes, the other BWG antennas were intended for operational use in the Networ

Consequently, after the construction phase was completed, they were subjected to a

intensive program of testing under operational conditions before they were declared ope

ational and accepted for tracking flight spacecraft as an element in an array or in 

stand-alone mode. The “operational” dates for all the BWG antennas are given in th

table below, and they generally followed the completion of the antennas by several month

DSN plans for BWG antenna construction in Spain and Australia were significant

affected by the dramatic events, described earlier, that occurred on the Galileo spacecra

in April 1991. To save the mission, DSN and Galileo engineers had proposed an alte

native mission using the spacecraft’s S-band, Low-Gain Antennas and an array of S-ban

antennas in Australia. This situation provided the DSN with the high-profile justific

tion needed for adding a fourth BWG antenna at Canberra (DSS 34). With design an

specification details already available from the Goldstone task, funding for constructio

of this antenna was quickly approved.

International bidding was opened for the erection of a fourth BWG antenna in Austra

with an option for two more when funding became available. (It was recognized th

significant savings could be realized by building the antennas in groups of three). Th

contract was won by the Spanish firm Schwartz-Hautmont, and construction began 

the Canberra site in July 1994.

Initially, problems with water percolation in the large excavation for the pedestal room

along with difficulties with the contract and Australian unions, caused significant del

to the construction schedule. Eventually these problems were dealt with, work resume

and the antenna was completed in November 1996, very close to the original sche

ule. After a short period of operational testing, the antenna was accepted for operation

support and immediately began supporting Galileo on S-band as part of the Canber

array. Later, the X-band uplink was added, and after a period of mission verificatio

testing, it began operational tracking support with X-band uplink and downlink 

August 1997, as mentioned above. A photograph of the completed antenna is show

in Figure 5-36.

378

Uplink-Downlink: A History of the Deep Space Networ
Two years after the Galileo high-gain antenna problem changed the course of BWG h

tory in the DSN, another spacecraft event occurred which once again changed the cour

of the program.

In August 1993, eleven months after launch and three days before insertion into Ma

orbit, communication with the Mars Observer spacecraft was lost and never recovered. 

the aftermath of this loss, NASA hastily proposed and funded a new mission to Mars 

be called Mars Global Surveyor (MGS). Its arrival at Mars toward the end of 1997 wou

37

The Galileo Era: 1986–1996

Figure 5-36. DSS 34 BWG antenna at the Canberra Deep Space Communications Comple

Australia, 1996. 
be just in time to create a conflict for X-band uplink support over Madrid with th

Cassini spacecraft scheduled for launch in October of that year. Once again there was 

strong programmatic need for an additional BWG antenna in the Network, this time 

the Madrid site. But this time, there was no funding immediately available. Fortunate

the DSN was able to reprogram sufficient money saved from the contracts for the fir

and second groups of three antennas to fund the option for the fifth BWG antenna 

Madrid. The contractor, Schwartz-Hautmont, began construction in June 1995. Despi

a water problem similar to the one that had occurred during construction in Austral

the antenna was completed by August 1997. System and mission verification tests fo

lowed, and the antenna was accepted for operations support in October 1997. 

To a large degree, the disposition of S-band and X-band capability among the differe

BWG antennas was driven by the funding available for procurement of the necessa

electronics packages. Although all of the antennas were capable of operation at Ka-ban

the use of Ka-band for spacecraft telecommunications links, except for Cassini, had n

matured beyond the need for a demonstration capability at one BWG antenna by th

end of 1997. The need for a full subnet capability was expected to develop in the yea

ahead. A Ka-band downlink capability existed only at DSS 25.

In late 1994, two 34-m BWG antennas that had formerly belonged to the U.S. Arm

and were situated near the Venus site at Goldstone were transferred as surplus property 

JPL. On transfer to the DSN, they became identified as DSS 27 and DSS 28 and we

designated as High Speed Beam Waveguide (HSB) type. These antennas were azimuth/el

vation mounted and, before they could be put into service, had to be stiffened an

strengthened to meet DSN standards for reliability and stability under conditions of co

tinuous use. DSS 27 was equipped to provide backup for the one remaining 26-m 

Goldstone, DSS 16, and to supplement DSN capability for high-Earth orbiter missio

like Infrared Space Observatory (ISO) and Solar Heliospheric Observatory (SOHO). DS

27 thus became a 34-m BWG that had the performance of a 26-m S-band antenna wi

one multifunction receiver and a low-power, 200-W transmitter. Like DSS 16, it was ope

ated remotely from the SPC located some ten miles away from the antenna site. Activatio

of DSS 28 was postponed for later, when funding for suitable electronics would becom

available. The photograph in Figure 5-37 shows a cluster of three 34-m BWG antenn

at Goldstone in 1995.

The times at which the various BWG antennas came into operational service in th

Network and their uplink and downlink operating bands as of December 1997 are sum

marized in the table below.

380

Uplink-Downlink: A History of the Deep Space Networ
DSN 34-Meter Beam Waveguide Antennas

DSS In Service Uplinks Downlinks

13* July 1990 S, X, Ka S, X, Ka

24 Feb. 1995 S S, X

25 Aug. 1996 X X, Ka

26 Aug. 1996 X X

27 July 1995 S S

28 Oct. 2000 N/A N/A

34 Nov. 1996 S, X S, X

54 Oct. 1997 S, X S, X

* DSS 13 for research and development use only. 

N/A: Electronics not available as of January 1998.

38

The Galileo Era: 1986–1996

Figure 5-37. Cluster of three 34-m BWG antennas at Goldstone, 1995.
With the completion of DSS 54 in 1997, the DSN finally had a complete subnetwo

of three 34-m BWG antennas, all of which were capable of operation at S, X, and K

band. By then, the trend for future missions was towards shorter passes and higher da

rates, a natural application for Ka-band uplinks and downlinks, as Joel G. Smith poin

ed out in the 1988 papers described earlier. In this context, the DSN was well position

to cope with mission requirements in the immediate future. The possibility of a justi

cation for more antennas seemed unlikely, and in terms of antennas, the DSN h

reached a plateau that appeared to extend well into the foreseeable future. 

382

Uplink-Downlink: A History of the Deep Space Networ
SIGNAL PROCESSING CENTER UPGRADE TASK

Background

The progressive enhancement of uplink and downlink capabilities through the Ma

II, Mark III, and Mark IVA models of the DSN has been traced in previous cha

ters. By 1993, the major goals of the Mark IVA configuration had been achieve

New antennas had been added to the DSN, Networks had been consolidated, an

the Signal Processing Centers (SPCs) had been integrated. Centralized control w

emerging as the established process for conducting mission operations at the SPC

Spacecraft data received at the Deep Space Communication Complexes (CDSCC

could now be returned to JPL at higher data rates and with fewer errors, thanks 

complementary improvements in the NOCC and GCF. Fewer errors meant less nee

for lengthy data recalls and faster delivery of the final data records to the flight pro

ects. Despite a few remaining functional and operational problems associated wi

the introduction of these changes, the Network was running smoothly and at ma

imum capacity. 

In 1993, and for the remainder of the Galileo Era, implementation of new uplink an

downlink capability in the DSN proceeded more on the basis of individual tasks hig

ly focused on specific objectives, rather than as part of a general overall enhanceme

of the entire Network, as had been the case in the past. Three such tasks, the Galil

telemetry, Beam Waveguide Antennas, and X-band uplinks, are examples of this chan

in approach and have already been discussed. 

While these tasks were in progress, however, a fourth major task involving changes an

additions at the subsystem level in most of the major systems of the DSN was bein

carried out at the SPCs. It was called the SPC Data Systems Upgrade and covered th

period 1990 through 1993. 

Signal Processing Centers Upgrade 

The drivers for the SPC upgrade were the future Mars Observer and International Sol

Terrestrial Physics (ISTP) missions. Between them, these two future missions plac

heavy demands for 26-m support, for X-band uplinks, and for additional telemet

downlinks, which exceeded the capability of the existing DSN. 

38

The Galileo Era: 1986–1996
There were four main objectives for this task:

1. Upgrade the telemetry system to support data rates up to 2.2 Mbps and provide Ree

Solomon decoding capability at the SPCs.

2. Add the 26-m Earth orbiter antennas to the existing SPC capability for centraliz

monitor and control of all Complex subsystems.

3. Increase the number of telemetry and command links to five per complex and expan

the capability to control them by adding two more Link Monitor and Control (LMC

computers and consoles.

4. Replace the obsolete Modcomp II computers with new Modcomp 7845 machine

which had significant growth potential.

The scope of the SPC upgrade task is identified in the SPC configuration diagram show

in Figure 5-38.

384

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-38. Signal Processing Center configuration, 1993.

26-METER

34-METER

34-METER

70 METER

ANTENNA RECEIVER

TRANSMITTER

OPEN-LOOP

RECEIVER

FREQUENCY

AND

TIMING

ANTENNA

POINTING SIMULATION

LINK

MONITOR

CONSOLE

COMPLEX

MONITOR

CONSOLE

DATA

LOG

RADIO

SCIENCE

VLBI

TELEMETRY

RADIO

METRIC

EXCITER COMMAND

COMM

DATA

LOG

MONITOR

AND

CONTROL

DATA

SPC TASK

ELEMENT

GCF TASK

ELEMENT
In the planning and execution of this task, great care was taken to avoid impacting th

SPC ability to continue full-scale mission operations throughout the entire period. Th

constraint led to a phased implementation plan that began in 1990 and ended in 199

The SPC implementation plan was carefully integrated with similar and interlockin

plans for the GCF and the NOCC. However, other events soon overtook the origin

plans, so by 1993, the original objectives had been extended. It was not until abo

1995 that the task of upgrading the SPCs was completed. 

SPC Telemetry

As part of the SPC data systems upgrade, the DSN Telemetry System, which began th

Galileo Era with four groups (strings) of data processing equipment, was expanded 

five strings, each capable of handling two data streams from a single spacecraft at selec

ed data rates.69 Each group was configured, monitored, and controlled by a Group Controll

that set the spacecraft data channels, monitored their performance, logged the data, an

formatted it for transmission to JPL via the GCF.

Groups 1 and 2 were composed of the original Mark IVA assemblies, subcarrier demo

ulator (SDA), Symbol Synchronizer (SSA), Maximum Likelihood Convolutional Decod

(MCD), and Telemetry Processor (TPA). Their convolutional decoding capability w

limited to constraint lengths of 24 or 32 at rate 1/2 for sequential decoding at da

rates of 3 bps to 5 kbps, and a constraint length of 7 at rate 1/2 or 1/3 for data rat

10 bps to 134 kbps, for maximum likelihood decoding. Uncoded data in the range 

bps to 15 kbps was processed by the TPA.

These capabilities were expanded in Groups 3 and 4 by the addition of new functio

and more advanced assemblies. For combining signals from up to eight receivers simu

taneously, a baseband combiner assembly (BBA) was added. In addition to the combinin

function, the BBA also performed subcarrier demodulation and symbol synchronizatio

and various combinations of all three functions. A more advanced version of the MCD

MCD II extended the data rate for maximum likelihood decoding to 2.2 Mbps, wh

frame synchronization at the frame transfer level was performed by a new frame sy

chronizer assembly (FSA). For telemetry data streams employing concatenated codin

a Reed-Solomon decoder for data rates of 2 bps to 2.2 Mbps was provided. Contr

and monitoring functions for each Group were performed by a new TPA, which al

extended the upper limit for uncoded data from 15 kbps to 2.2 Mbps and carried o

sequential decoding functions on either channel in the range 3 bps to 5 kbps.

38

The Galileo Era: 1986–1996
With the exception of baseband combining, the capabilities of Groups 3 and 4 we

replicated in Group 5. 

Although the older Mark IVA assemblies in Groups 1 and 2 were eventually replac

with equipment which was equivalent to that in Group 5, the former data rates an

formats were retained in these two Groups.

Over the next several years, improvements were made as the need arose. Responding 

requests from the DSCCs, a self-test capability was added to the Telemetry Group Controll

(TGC) and Telemetry Channel Assembly (TCA) software in 1995 to reduce the tim

required by the station operators to carry out pre-track readiness checks. 

Following a long period of complex development and an exhaustive series of tests 

Goldstone, new Block III Maximum Likelihood Decoders (B3MCD) were added to th

telemetry subsystem at each Complex in 1997. The B3MCD could be selected as a

alternative to the standard MCD in one channel of each of telemetry Groups 3, 4, an

5. The B3MCD responded to the requirements of Mars Pathfinder and Cassini for ma

imum likelihood decoding of convolutional codes of constraint length 15 and rate 1/

in addition to the standard (K = 7, R = 1/2) decoding provided by the DSN. The add

tion of the B3MCD provided 1 dB to 2 dB improvement in bit signal-to-noise rat

compared to the existing (7, 1/2) MCD. 

The B3MCD represented not only a major increase in downlink capability, but also 

major accomplishment in new VLSI technology. It grew out of a 1988 concept by J. 

Statman for a powerful new decoding device for the long constraint length (15), hig

rate (1/4) convolutional code to be employed on the Galileo 1989 X-band mission f

returning Io Encounter science at a high data rate (134 kbps) from Jupiter.70 The ne

Big Viterbi Decoder (BVD) grew out of two contemporary developments in the DSN

Advanced Systems program—the successful search for a long constraint length code wi

a “2 dB additional coding gain,”71 and the burgeoning expertise in Very Large Sca

Integrated (VLSI) technology.72

Early progress was rapid, and by mid-1991 a prototype had been completed and ru

successfully. Using experience gained from the prototype and improved VLSI chips, 

new “single board” decoder was being constructed for actual implementation in th

DSN. The new BVD would be programmed to decode convolutional codes having co

straint length of 2 to 15 at rates of 1/2 to 1/6, and it would handle the highest Galil

telemetry data rate of 134 kbps.73

386

Uplink-Downlink: A History of the Deep Space Networ
But the great expectations that were held for the BVD would not be fulfilled. In th

wake of the Galileo HGA problem in 1991, further work on the BVD was suspende

and Statman was redirected to manage the DGT task in an effort to recover downlin

data from the Galileo S-band mission at data rates of 10 bps to 100 bps.

Later, the need for an improved decoder for the Telemetry System prompted the reviv

of the BVD concept. However, it was an entirely new development task using even mo

advanced VLSI technology that resulted in the design for Block 3 Decoders that we

eventually produced for implementation at all three complexes in 1997. 

This brought the DSS Telemetry Subsystem to the generic configuration shown in fun

tional form in Figure 5-39. 

The number of telemetry groups at each complex varied according to the number 

antennas to be supported, eight being the maximum, at Goldstone. A Baseband Pat

panel provided flexibility for switching or combining multiple inputs from up to twel

Block V receivers. Each group contained the assemblies necessary for performing th

telemetry-related functions of baseband or symbol stream combining, demodulation, b

and frame synchronization, and convolutional, Reed-Solomon, or sequential decodin

38

The Galileo Era: 1986–1996

Figure 5-39. DSN Telemetry Subsystem, 1997.

Baseband Inputs

from all (12)

Block V Receivers

Baseband Patch Panels

SPC Local Area Network

Telemetry Group Controller

DSS Telemetry Subsystem Group, (1 of 8)

Baseband

Assy

PSK

Demod

Bit

Synch

MCD

Block 2

MCD

Block 3

Symbol Stream Input

from

Block V Receiver

High Rate

Local Area Network

GCF

Transmission

System

Station

Communications

Processor

Data Return

to JPL

Frame

Synch

ReedSoloman

Decoder

Sequential

Decoder
Output data was delivered to a high-rate Local Area Network for transport to JPL v

the GCF. To form a link for a specific spacecraft pass, the elements of any group cou

be configured from a centralized control location via the SPC Local Area Network. 

By the time the DSN made the transition from the Galileo Era to the Cassini Era 

1997, the DSN Telemetry System had reached the functional form in which it wou

support the new missions of that era, Mars Global Surveyor, Mars Pathfinder, and Cassin

SPC Command

The DSN Command System also was improved to meet increased demands for mo

simultaneous uplinks with higher performance, as part of the SPC upgrade period 

the mid-nineties.74 Not only were the number of independent command channels increas

from four to five, but switching arrangements were added to allow station controlle

greater flexibility in switching any command channel to any exciter-transmitter comb

nation. Command data rates and subcarrier frequencies were increased, and provisio

was made for the command system to be operated directly from the NOCC or a remo

Mission Operations Center (MOC). 

At each complex, each of the five groups in the command subsystem comprised a Comman

Processor Assembly (CPA), Command Modulation Assembly (CMA), and Comman

Switching Assembly (CSA).

The CPA contained software that provided electrical interfaces with all other related su

systems in the Complex and with the NOCC and MOC. It accepted the seri

pulse-code-modulated (PCM) command data stream from the MOC and delivered 

to the CMA for modulation on to a subcarrier. 

The CMA generated the desired subcarrier in the frequency range of 100 Hz to 16 kH

and modulated it with the command data received from the CPA. Phase Shift Key

(PSK) or Frequency Shift Keyed (FSK) modulation was available at a command da

rate ranging from 1 bps to 2,000 bps. 

The CSA connected the command-modulated output of the CMA to a designated excit

for generating the S-band or X-band carrier, which was finally radiated by the tran

mitter and assigned antenna. These functions are shown in Figure 5-40, which illustrat

the DSCC Command System in 1996. 

388

Uplink-Downlink: A History of the Deep Space Networ
In 1997, an additional 34-m antenna, the BWG, with a 4-kW X-band transmitter, w

added to each complex and integrated with the command system by means of th

Command Switch Matrix.

In the upgraded SPC, assignment of command groups to specific exciters, transm

ters, and antennas was carried out by a single “complex” operator. The resultin

“uplink” was then configured by a “link” operator to support a specific spacecraft 

the next scheduled tracking and commanding period. After the correct configuratio

and operation of the link had been validated, it was turned over to the MOC f

use in transmitting the desired commands to the spacecraft. Because the DSN Comman

System had the potential to cause unintended, undesirable, or irreversible actions 

a spacecraft, particular care was taken to ensure that the command data radiated b

the transmitter was identical to the command data input to the CPA. This assuran

was provided by verification and confirmation functions as an integral part of th

command system.

After the final installation of CPA/CMA software in September 1995, each complex h

the capability to support five active command uplinks simultaneously, two of whi

38

The Galileo Era: 1986–1996

Figure 5-40. DSCC Command System, 1996.

DEEP SPACE STATIONS

ANTENNA MECHANICAL

AND ANTENNA 

MICROWAVE SUBSYSTEMS

SIGNAL PROCESSING CENTER

COMMAND SUBSYSTEM

COMMAND

PROCESSOR

ASSEMBLY

(CPA)

COMMAND

MODULATOR

ASSEMBLY

(CMA)

COMMAND 2

COMMAND 3

COMMAND 4

COMMAND 5 LINK 5

M & C

LINK 4

M & C

LINK 2

M & C

LINK 1

M & C

COMPLEX

M & C

ODR

LAN TO/FROM

NOCC/MOC

NOTES

AT GOLDSTONE THE SIGNALS

TO/FROM DSS 12 AND DSS 16

EXCITERS WILL BE VIA GCF

INTERSITE ANALOG COMMUNICATIONS SUBSYSTEM

FTS

GROUND

COMMUNICATIONS

FACILITY

DIGITAL

COMMUNICATIONS

SUBSYSTEM

LINK 3

M & C

DISK

70-METER

34-METER

STANDARD

26-METER

10 KW

SFL

20 KW

20 KW

20 KW X-BAND

DEEP

SPACE

S-BAND

C

O

M

M

A

N

D

S

W

I

T

C

H

M

A

T

R

I

X

20 KW

400 KW

TRANSMITTER

SUBSYSTEM

RECEIVEREXCITER

SUBSYSTEM

DEEP SPACE

AND EARTH

ORBITER 

S-BAND

DEEP

SPACE

X-BAND

EARTH

ORBITER 

S-BAND

70 KHz

34-METER

HIGH EFFICIENCY
could be on X-band. Any uplink could be assigned to any of the active antennas o

the complex and could (after proper validation by the DSN) be operated for the pu

pose of sending commands from a remote MOC (such as a NASA Center other tha

JPL, or an agency other than NASA).

SPC Tracking 

In addition to the telemetry and command subsystems discussed above, DSN plans f

upgrading the SPCs included the tracking subsystem. As a result of the Network conso

idation program some years earlier, the 9-m and 26-m antennas, formerly operated b

GSFC as part of the Spaceflight Tracking and Data Network (STDN), had become 

DSN responsibility. DSN plans in 1990 called for them to be added to the DSCC Trackin

Subsystem and integrated into the SPCs at all complexes by May or June of 1995.75

In a functional sense, the Tracking Subsystem consisted of four basic groups of equi

ment (hardware and software), one for each type of antenna—namely, 70-m, 34-m STD

34-m HEF, and 9-m/26-m—where the 9-m/26-m antennas were represented by a si

gle type. The principal application of the 70-m/34-m group was in tracking deep spa

or high-Earth orbiting spacecraft. The principal application of the 9-m/26-m group w

in initial acquisition of all spacecraft for which the DSN was to provide tracking an

data acquisition services, and in tracking low-Earth orbiting spacecraft.

All 70-m/34-m groups were identical and contained a Metric Data Assembly (MDA) an

a Sequential Ranging Assembly (SRA). Their primary functions were to generate radio me

ric data consisting of Doppler, range, differenced range versus integrated Doppler (DRVID

and uplink tuning data. Performance monitoring and data validation were secondary fun

tions. The primary functions were applied to S-band and X-band uplinks and downlin

as determined by the capability of the antennas to which they were assigned. Each grou

was permanently associated with a specific transmitter-exciter-receiver combination and, li

all other subsystems in the SPC, could be configured and controlled from the centra

located DSCC Monitor and Control (DMC) station via a Local Area Network.

With the exception of the MDA, which was replaced by a Metric and Pointing Assemb

(MPA), the composition of the 9-m/26-m groups was similar to the 70-m/34-m group

Their primary functions, however, were very different. The main purpose of the MP

was to point the 9-m/26-m antenna, a function which was carried out by a spec

Antenna Pointing Subsystem on the other antennas.

390

Uplink-Downlink: A History of the Deep Space Networ
Using trajectory data unique to its specific site and spacecraft of interest supplied by a

external entity (generally GSFC), the MPA generated spacecraft signal acquisition param

eters in the form of topocentric angles, Doppler frequency, and range delay. These da

were used to point the antenna in various modes of tracking and to validate the Doppl

and ranging performance of special ranging equipment used on these antennas for su

port of older Earth-orbiting missions. The MPA also used angle and acquisition data 

generate predictions for any colocated antenna. This capability was frequently used 

point the 34-m antennas during the initial downlink signal acquisition sequence fo

lowing a spacecraft launch, when the spacecraft trajectory was not known with sufficie

precision to point the narrow-beam 34-m antennas. The MPA controlled and mon

tored the SRA in a manner identical to the MDA. 

The functions just described for all four types of antennas are shown in block diagra

form in Figure 5-41.

39

The Galileo Era: 1986–1996

Figure 5-41. DSCC Tracking Subsystem, 1995.

DSS

70 M

ANT

S/S

LAN

TXR

UWV

34 M

(STD)

ANT

S/S

LAN

TXR

UWV

RCV

RCV

34 M

(HEF)

ANT

S/S

LAN

TXR

UWV

RCV

9 M/26 M

ACC TXR

UWV

SBE

MFR

DTK

DTK

DMD

DMC

SPC NOCC

NAV

SFOC

NAV TEAMS

EXTERNAL

AGENCIES

EXTERNAL

USERS

SRA

MDA

DTK

L

O

C

A

L

A

R

E

A

N

E

T

W

O

R

K

L

O

C

A

L

A

R

E

A

N

E

T

W

O

R

K

D

I

G

I

T

A

L

C

O

M

M

S

U

B

S

Y

S

T

E

M

DTK

MPA

SRA

RE NOTE:

NSS

NMC

NTK

PRIMARY DATA FLOW
In this figure, each group of the DSCC Tracking Subsystem is represented by the design

tor, DTK. A fifth group was added in 1997 to accommodate the new 34-m BWG antenna

Implementation of the new MDA at the SPCs in Madrid, Canberra, and Goldston

was completed in early 1993 without significant problems. This was followed a fe

months later by the MPA, so that by the end of the year, the DSCC Tracking Subsyste

as originally planned was in place and supporting mission operations. 

By that time, however, several major events had occurred that would materially affe

the just-completed DSCC Tracking Subsystems. These events were the failure of th

Galileo HGA and subsequent emergence of the DGT and BVR to support a Galil

S-band mission, encouraging results from development tests of an X-band exciter an

approval of plans for another set of 34-m antennas (BWG). The BVR would repla

the existing Block IV receivers, the new exciter would bring X-band uplinks to the DSN

and the BWG antennas would increase the number of tracking system groups to fiv

In all three instances, new MDA software and hardware was required.

Although an early version of the BVR appeared at Goldstone at the beginning 

1993 for testing with the Galileo downlink, it was not until May of 1995 that 

was implemented in full operational form at all complexes and ready to begin accep

ance testing with the new MDA software. These tests revealed problems with missin

Doppler data between the BVR and the MDA and required more changes to th

MDA software. The DSN was to switch to the BVR for Galileo downlink missio

operations on 18 September 1995. Also at that time, the Galileo downlink wou

be switched permanently to the suppressed carrier mode. Galileo was approachin

Jupiter, and good Doppler data was vital to the success of the Galileo Jupiter Orb

Insertion sequence. Under pressure of these impending changes, the new MDA sof

ware was developed; checked in the DSN test facility at JPL, DTF 21; tested 

Goldstone (DSS 14); shipped to the other complexes; and installed in eight week

It was soon followed by a new software package for the SRA, which, together wi

a new hardware board, allowed it to generate ranging data with the BVR. It was th

software that was used to support the highly successful Galileo mission operations 

Jupiter in December 1995. 

Subsequently, more changes were made to the MDA software to add operability enhanc

ments requested by the users at the Complexes, to improve the Monitor interfaces, an

to provide an interface to the Block V X-band exciter. Although this latter capabili

was not driven by Galileo, it would be required by other spacecraft: Mars Global Surveyo

Mars Pathfinder, and Cassini, all to be launched within the next year or two. 

392

Uplink-Downlink: A History of the Deep Space Networ
By 1997, when the new beam waveguide antennas came into operation, the DSC

tracking subsystem had been greatly expanded at each Complex to accommodate th

additional X-band uplink and downlink.

In addition to the DSCC Tracking Subsystem, there was another important comp

nent of the overall DSN tracking system located at each complex. This was calle

the DSCC Media Calibration Subsystem (DMD). The two principal functions of th

DMD were to make continuous measurements of ground weather parameters and 

make continuous measurements of ionospheric conditions at the site. These data we

formatted and transmitted to the NOCC for use by the Navigation Team in co

recting radio metric data for media effects before it could be used for orb

determination purposes.

The local ground weather observations were made by a meteorological monitorin

assembly and had gradually been improved over the years. However, the ionospher

data had for many years been supplied to the DSN by other agencies and were bas

on ad hoc observations of an aging Earth satellite (ETS-6) from several remote-obser

ing sites. This unsatisfactory method of determining total electron content (TEC) w

replaced in 1992 by a system that measured TEC continuously at the local site. Bas

on Global Positioning Satellite (GPS) technology, the new GPS Receiver/Process

Assembly (GRA) could automatically acquire and track at least four GPS space veh

cles when they were above the local horizon without requiring operator interventio

The GRA computed the differential group delay and differential phase delay betwee

the L1 and L2 carriers from the space vehicles and estimated the slant TEC. Th

DMD made provisions for monitoring, validating, and recording the TEC data pri

to its transmission to JPL.

Network Operations Control Center (NOCC)

Located at JPL, the NOCC furnishes coordination, control, and monitoring services 

the Network and serves as the single data and communications interface between th

Complexes and the external users of the DSN. Although these functions were not change

they were significantly affected by the SPC upgrade, and necessitated an upgrade 

existing NOCC capability.

Concurrent and interlocked with the upgrade of the SPC, the task of upgrading th

NOCC was directed toward complementing the new capabilities of the SPC and impro

ing the reliability and operating efficiency (operability) of the Center. The primary functio

of the NOCC—providing a control interface between the Complexes and external use

39

The Galileo Era: 1986–1996
such as the Flight Projects, and providing a central facility for the control and mon

toring of the DSN—were not changed.

The upgraded NOCC gave its operators better information with which to monitor th

performance and status of the tracking stations, resulting in a reduced need for verb

interaction with the station operators. The upgraded SPC gave the station operato

more information with which to identify and correct problems independently of th

NOCC operators. The new ability of the SPCs to perform frame synchronization an

decommutation of telemetry data and to calculate the deviation of actual performan

from predicted values was a key factor in this area. 

Other areas of activity in the NOCC saw similar benefits. A manual procedure f

reporting frequency and timing offsets was replaced by an automatic procedure, and th

need for a member of the radio science team to be present at a station during radio sc

ence activity was eliminated. Faster identification of operational errors and the reductio

of command, tracking, and monitor communications traffic between the NOCC an

the complexes led to significant improvement in the quality of the VLBI navigation da

generated by the Network. 

The NOCC upgrade was carried out as planned and, when completed in 1993, repr

sented a significant advance in the efficiency of centralized control of the Networ

Except for a change in its function as an interface between external users and the DSN

the NOCC continued to function as an integral part of the DSN without further mo

ification through the end of the Galileo Era.

Ground Communications Facility

In order to make the changes that were planned for the SPC, it was necessary to upgra

the existing communication facilities at the three Signal Processing Centers (SPCs), 

well as those at the Central Communication Terminal (CCT) at JPL. This became th

Ground Communication Facility (GCF) Upgrade Task, and it ran concurrently wit

and with the same constraints as, the other upgrade tasks.

Prior to the GCF upgrade, the interchange of data between the subsystems at eac

SPC was carried on a single Ungerman-Bass Local Area Network (LAN). To hand

the additional telemetry, command, and tracking equipment that came with the SP

upgrade, the GCF task provided two new LANs, each connected to a new Statio

Communications Processor (SCP). One LAN was linked to the old UBI LAN via 

“gateway” and was designated as the SPC LAN. The other was designated as the H

394

Uplink-Downlink: A History of the Deep Space Networ
rate LAN. Interactive traffic between the Complex/Link Controllers on the UBI LA

and the telemetry, command, and tracking subsystems on the SPC LAN flowed throug

the “gateway.” Traffic between these subsystems and the NOCC moved through th

SCP. The Hi-rate LAN handled only telemetry, transporting the output from all fi

telemetry channels to the SCP. The SCP provided digital recording and formattin

functions for the data on both LANs before transmitting it to the Centr

Communications Terminal (CCT) at JPL via wideband satellite and ground comm

nication circuits provided by NASCOM. 

The CCT at JPL was the terminal for all voice and data circuits between the NOC

and each of the complexes. Located at the CCT, the Central Communications Process

(CCP) could be viewed as a mirror image of the Station Communications Process

with the GCF transmission subsystem, and it included the far-reaching communic

tion channels of NASCOM, forming the link between them. A LAN connected th

CCP with a digital recording subsystem, a monitor and control subsystem, and thr

“gateways.” It was through these “gateways” that the GCF digital communications su

system connected the Complexes and the NOCC to the outside world. The NOC

gateway provided for all NOCC traffic. An “External User” gateway conducted tra

fic with remote Mission Operations Control centers such as GSFC or space agenci

in foreign countries, while the third “SFOC” gateway handled the data flow betwee

the SFOC* and the DSN.

A simplified diagram of the subsystems of the GCF as it was configured in 1992 

given in Figure 5-42. 

The Big Pipe and Little Pipe elements of the GCF transmission system were descri

tors for the NASCOM communication channels. They delivered data to the CCT 

672 kbps and 64 kbps, respectively, from Madrid and Canberra, and 1.2 Mbps and 22

kbps from Goldstone.

Implementation of these changes was to be phased in with incremental changes 

SPC capability and was in progress when further changes were imposed by the requir

ments of the Galileo mission redesign in 1993. To meet the arraying requirements 

39

The Galileo Era: 1986–1996

* At various times, the facility at JPL from which JPL inflight missions were controlled was known by differe

names that reflected the changing scope of its activities. Some of these names include the Space Flight Operatio

Facility (SFOF), the Mission Control and Computing Center (MCCC), the Space Flight Operations Center (SFOC

and the Multimission Ground Data System (MGDS). At the time of the GCF upgrade, it was called the SFO
396

Uplink-Downlink: A History of the Deep Space Networ

Figure 5-42. Ground Communications Facility, 1992. 

DSCC SUBSYSTEMS

DMCDTM

DGT

UBI/LAN

ODR

OFF LAB POCC

(GSFC, ISAS, ...)

GATEWAY

GCF

STATION COMM.

PROCESSOR

(SCP)

• FORMAT• SWITCH• RECORD

GDC/

GDR

GTM

• TRANSMISSION• BIG PIPE• LITTLE PIPE

GCF

MONITOR AND

CONTROL

(GMC)

GMC

CENTRAL COMM.

PROCESSOR

(CCP)

• FORMAT• SWITCH

GDC

EXTERNAL

USER

GATEWAY

(EUG)

GDC

GCF

RECORD

GDR

NOCC

GATEWAY

GDC

SFOC

GATEWAY

GDC

CCG

IDR

P80

LAN

MGDS(SFOC)

NOCC(NSS, RT)(NAV)(VLBI)

JPL/CCT

DSCCs

CTA 21

MIL 71

• GDC - GCF DIGITAL COMM. SUBSYSTEM• GMC - GCF MONITOR AND CONTROL SUBSYSTEM• GDR - GCF DATA RECORDS SUBSYSTEM• GTM - GCF TRANSMISSION SUBSYSTEM

REMARK:

OTHER GCF SUBSYSTEMS

• GVC - GCF VOICE SUBSYSTEM• GTY - GCR TELETYPE SUBSYSTEM

DSCC

LAN

SUBSYSTEM

(DLN)
the DGT, a special channel having a capacity of 400 kbps was established betwee

Goldstone and Canberra. This channel, which consisted of two standard intersite ci

cuits, was routed through the CCT for monitor and control purposes and was specifi

to require an error rate better than 2 x 10-7 with a 1-way, 2-hop delay that would n

exceed 0.75 second. 

As part of the original SPC upgrade, new capability had been added to all DSN su

systems to allow them to transfer data files among each other. This was extended 

1993 to include the SFOC by providing suitable hardware and software in the GC

digital communications subsystem for routing and monitoring non-real-time data fi

transfers. This service eventually came into regular use for automatic post-pass tran

fer (PPT) of data files between the complexes and the flight project mission contr

centers, and it proved to be of great value in streamlining the conduct of routin

DSN operations. 

39

The Galileo Era: 1986–1996
A SUCCESSFUL CONCLUSION

The successful conclusion of the Galileo Prime Mission in December 1997 brought th

Galileo Era to a close. The effort devoted to conducting mission operations, for bo

the spacecraft and the DSN, was scaled back but continued, at a much reduced lev

as the Europa Continuation Mission. By that time, the Galileo project had been on th

DSN “books” in various forms for nearly twenty years. Also, NASA had recently announc

a new initiative for “faster, better, cheaper” spacecraft. Cassini, the last of the planeta

“mega-spacecraft,” had already been launched and was on its way to Saturn. 

The Cassini Era was at hand.

398

Uplink-Downlink: A History of the Deep Space Networ
Endnotes

1. Bruce Murray, Journey Into Space (New York: W. W. Norton, 1989), pp. 227, 22

321.

2. C. Stelzried, L. Effron, and J. Ellis, “Halley Comet Missions,” TDA Progress Repo

PR 42-87, July-September 1986 (15 November 1986), pp. 240–42. 

3. C. T. Stelzried and T. Howe, “Giotto Mission Support,” TDA Progress Report P

42-87, July-September 1986 (15 November 1986), pp. 243–48. 

4. N. A. Mottinger and R. I. Premkumar, “Giotto Navigation Support,” TDA Progre

Report PR 42-87, July-September 1986 (15 November 1986), p. 249–62. 

5. R. Linfield and J. Ulvestad, “Source and Event Selection for Radio-Planetary Fram

Tie Measurements Using the Phobos Landers,” TDA Progress Report PR 42-9

October/December 1987 (15 February 1988), pp. 1–12.

6. K. M. Cheung and F. Pollara, “Phobos Lander Coding System: Software an

Analysis,” TDA Progress Report PR 42-94, April/June 1988 (15 August 1988), p

274–86.

7. P. H. Stanton and H. F. Reilly, Jr., “The L-/C-band Feed Design for the DSS 14 7

Meter Antenna (Phobos Mission),” TDA Progress Report PR 42-107, Jul

September 1991 (15 August 1991), pp. 364–83.

8. J. Withington, “DSN 64-Meter Antenna L-band (1688-MHz) Microwave Syste

Performance Overview,” TDA Progress Report PR 42-94 April/June 1988 (1

August 1988), pp. 294–300.

9. C. E. Hildebrand, B. A. Iijima, and W. M. Folkner, “Radio-Planetary Frame T

from Phobos-2 VLBI Data,” TDA Progress Report PR 42-119, July-Septemb

1994 (15 November 1994).

10. A. L. Berman, “Deep Space Network Preparation Plan for Magellan Project,” DS

Document 870-73, JPL D-4852 (Pasadena, California: JPL, 15 March 1989).

39

The Galileo Era: 1986–1996
11. A. L. Berman, D. J. Mudgway, and J. C. McKinney, “The 1986 Launch of th

Galileo Spacecraft via the Space Transportation System,” TDA Progress Report P

42-72, October-December 1982 (15 February 1983), pp. 186–99.

12. Jet Propulsion Laboratory, “Magellan Spacecraft Final Report,” Internal Repo

MGN-MA-011 (Pasadena, California: Martin Marietta Technologies, Inc., Janua

1995), pp. 50–51.

13. Rick Gore, “Neptune; Voyager’s Last Picture Show,” National Geographic Magazi

(August 1990): 35–64.

14. Bradford A. Smith, “Voyage of the Century,” National Geographic Magazine (Augu

1990): 48–65. 

15. W. J. O’Neill et al., “Project Galileo; Mission and Spacecraft Design,” JPL D-051

Jet Propulsion Laboratory, January 1983 (compilation of papers presented at AIA

21st Aerospace Sciences Meeting, Reno, Nevada, 10–13 January 1983).

16. A. L. Berman, D. J. Mudgway, and J. C. McKinney, “The 1986 Launch of th

Galileo Spacecraft via the Space Transportation System,” TDA Progress Report P

42-72, October-December 1982 (15 February 1983), pp. 186–99.

17. S. Dolinar, “A New Code for Galileo,” TDA Progress Report PR 42-9

January/March 1988 (15 May 1988), pp. 83–96.

18. D. J. Mudgway, Jet Propulsion Laboratory, Telecommunications and Da

Acquisition Office, interoffice memorandum to R. J. Amorose, from “Galil

Convolutional Coding Proposal,” 6 July 1987.

19. J. W. Layland et al., “Galileo Array Study Team Report,” TDA Progress Report P

42-103, July/September 1990 (15 November 1990), pp. 161–69.

20. T. K. Peng, J. W. Armstrong, J. C. Breidenthal, F. F. Donivan, and N. C. Ham

“Deep Space Network Enhancement for the Galileo Mission To Jupiter,” IAF-8

304 (Innsbruck, Austria: International Astronautical Federation, October 1986).

21. W. J. O’Neil, “The Galileo Messenger,” Issue 31 (Pasadena, California: Galil

Project Office, JPL, February 1993), p. 9.

400

Uplink-Downlink: A History of the Deep Space Networ
22. L. Deutsch and J. Marr, “Low Gain Antenna S-band Contingency Mission,” Galil

Project Document 1625-501 (Pasadena, California: JPL, 10 April 1992).

23. J. I. Statman, “Optimizing the Galileo Space Communication Link,” TDA Progre

Report PR 42-118 (15 February 1994), pp. 114–20.

24. P. E. Beyer, D. J. Mudgway, and M. M. Andrews, “The Galileo Mission to Jupite

Interplanetary Cruise; Post-Earth Encounter through Jupiter Orbit Insertion,” TD

Progress Report PR 42-125, March/April 1996 (15 May 1996), pp. 1–16. 

25. P. E. Beyer, B. G. Yetter, R. G. Torres, and D. J. Mudgway, “Deep Space Netwo

Support for the Galileo Mission to Jupiter: Jupiter Orbital Operations From Pos

Jupiter Orbit Insertion Through the End of the Prime Mission,” TDA Progre

Report PR 42-133, March/April 1998 (15 May 1998), pp. 1–23.

26. Willis G. Meeks and Ed. B. Massey, “Ulysses: An Investigation of the Polar Regio

of the Heliosphere,” personal communication, July 1997. 

27. European Space Agency, “The Ulysses Data Book,” European Space Agen

Document, ESA-BR 65 (Noordwijk, Netherlands: ESTEC, June 1990). 

28. D. M. Enari, “DSN Preparation Plan: Ulysses Project,” JPL Document D-150

(Pasadena, California: JPL, 1 August 1985).

29. M. R. Traxler, “DSN Support of Mars Observer,” TDA Progress Report PR 42-11

January-March 1993 (15 May 1993), pp. 118–22.

30. T. A. Rebold, A. Kwok, G. E. Wood, and S. Butman, “The Mars Observer Ka-ban

Link Experiment,” TDA Progress Report PR 42-117, January-March 1994 (15 M

1994), p. 250.

31. Earl J. Montoya and Richard O. Fimmel, “Space Pioneers and Where They A

Now,” NASA EP-264 (Washington, District of Columbia: NASA Education

Affairs Division, 1987).

32. Richard, P. Rudd, “Voyager Approach to Maintaining Science Data Acquisition f

a 30-Year Extended Mission,” Voyager Project Web site, http://jpl.nasa.go

voyager/30plan.html (Pasadena, California: JPL, November 1997).

40

The Galileo Era: 1986–1996
33. N. A. Fanelli, “JPL Emergency Support of TDRSS and Compatible Satellites,” TD

Progress Report PR 42-82, April-June 1985 (15 August 1985), pp. 120–24.

34. N. A. Fanelli to D. J. Mudgway, “Emergency Cross Support Agreements,” priva

communication, 11 November 1997.

35. B. Wood, “Report on the Mechanical Maintenance of the 70-Meter Antennas

DSN 890-257, JPL D-10442 (Pasadena, California: JPL, 31 January 1993

pp. 5, 207.

36. Donald H. McClure, “Rehabilitation of the DSN 70-Meter Antennas: The DS

Antenna Rehabilitation Team Final Report,” DSN Document 890-226 (Pasaden

California: JPL, 1 November 1989).

37. D. W. Brown, H. W. Cooper, J. W. Armstrong, and S. S. Kent, “Parkes-CDSC

Telemetry Array: Equipment Design,” TDA Progress Report PR 42-85, Januar

March 1986 (15 May 1986), pp. 85–110.

38. J. W. Layland et al., “Interagency Array Study Report,” TDA Progress Report P

42-74, April-June 1983 (15 August 1983), pp. 117-48.

39. D. W. Brown, W. D. Brundage, J. S. Ulvestad, S. S. Kent, and K. P. Barto

“Interagency Arraying for Voyager-Neptune Encounter,” TDA Progress Report P

42-102, April-June 1990 (15 August 1990), pp. 91–118. 

40. Andrew J. Butrica, To See the Unseen; A History of Planetary Radar Astronomy, NAS

SP-4218 (Washington, District of Columbia: NASA, NASA History Office, 1996

41. J. R. Paluka, “100-kW, X-band Transmitter for FTS,” Technical Report TR 3

1526, Vol. VIII, January/February 1972 (15 April 1972), pp. 94–98.

42. A. L. Berman, “The Gravitational Wave Experiment: Description and Anticipat

Requirements,” TDA Progress Report PR 42-46, May/June 1978 (15 August 1978

pp. 100–08.

43. T. A. Komarek, J. G. Meeker, and R. B. Miller, “ISPM X-band Technolo

Demonstration, Part 1. Overview,” TDA Progress Report PR 42-6

January/February 1981 (15 April 1981), pp. 50–62.

402

Uplink-Downlink: A History of the Deep Space Networ
44. J. G. Meeker and C. T. Timpe, “X-band Uplink Technology Demonstration at DS

13,” TDA Progress Report PR 42-77, January-March 1984 (15 May 1984), pp. 24–3

45. R. Stevens, Jet Propulsion Laboratory, Telecommunications and Data Acquisitio

Office, Interoffice Memorandum to P. T. Lyman, “X-band Uplink Experiment f

Galileo” (3 June 1982).

46. Frank B. Easterbrook, “Gravitational Wave Searches with Ground Trackin

Networks,” IAF-85-386 (paper presented at the 36th Congress of the Internation

Astronautical Federation, Stockholm, Sweden, October 1985).

47. D. J. Mudgway, “1986 Galileo Project NASA Support Plan,” JPL Document D-58

(Pasadena, California: JPL, 15 November 1983). 

48. R. M. Perez, “Improvements in X-band Transmitter Phase Stability Throug

Klystron Body Temperature Regulation,” TDA Progress Report PR 42-10

January-March 1992 (15 May 1992), pp. 114–20.

49. S. Hinedi, “A Functional Description of the Advanced Receiver,” TDA Progre

Report PR 42-100, October-December 1989, (15 February 1990), pp. 131–49.

50. University of Padua, “The Galileo Spacecraft: A Legacy for Future Space Fligh

(proceedings of the Three Galileos Conference, Padua, Italy, 1997).

51. Jet Propulsion Laboratory, Telecommunications and Mission Operatio

Directorate, “Galileo Low Gain Antenna S-band Contingency Mission,” present

tion to NASA Headquarters, JPL Document 1625-497 (20 March 1992).

52. J. I. Statman, “Optimizing the Galileo Space Communication Link,” TDA Progre

Report PR 42-116, October-December 1993 (15 February 1994), pp. 114–20.

53. J. W. Layland et al., “Galileo Array Study Team Report,” TDA Progress Report P

42-103, July/September 1990 (15 November 1990), pp. 161–69.

54. A. Mileant and S. Hinedi, “Overview of Arraying Techniques in the Deep Spa

Network,” TDA Progress Report PR 42-104, October-December 1990 (1

February 1991), pp. 109–15.

40

The Galileo Era: 1986–1996
55. S. Dolinar, “A New Code for Galileo,” TDA Progress Report PR 42-93, Januar

March 1988 (15 May 1988), pp. 83–96. 

56. H. Tsou, B. Shah, R. Lee, and S. Hinedi, “A Functional Description of the Buffer

Telemetry Demodulator (BTD),” TDA Progress Report PR 42-112, Octobe

December 1992 (15 February 1993), pp. 50–73.

57. S. Dolinar and M. Belongie, “Enhanced Decoding for the Galileo S-band Mission

TDA Progress Report PR 42-114, April-June 1993 (15 August 1993), pp. 96–11

58. S. Million, B. Shah, and S. Hinedi, “A Comparison of Full Spectrum and Comple

Symbol Combining Techniques for the Galileo S-band Mission,” TDA Progre

Report PR 42-116, October-December 1993 (15 February 1994), pp. 128–49.

59. T. T. Pham, S. Shambayati, D. E. Hardi, and S. G. Finley, “Tracking the Galil

Spacecraft with the DSCC Galileo Telemetry Prototype,” TDA Progress Report P

42-119, September/October 1994 (15 November 1994), pp. 221–35.

60. Jet Propulsion Laboratory, “The Galileo Messenger,” Issue 39, Galileo Proje

Office, JPL (July 1996).

61. J. G. Smith, “Ka-band (32 GHz) Downlink Capability for Deep Spa

Communications,” TDA Progress Report PR 42-88, October/December 1986 (1

February 1987), pp. 96–103.

62. J. G. Smith, “Proposed Upgrade of the Deep Space Network Research an

Development Station,” TDA Progress Report PR 42-88, October/December 198

(15 February 1987), pp. 158–63.

63. R. C. Clauss and J. G. Smith, “Beam Waveguides in the Deep Space Network

TDA Progress Report PR 42-88, October-December 1986 (15 February 1987

pp. 174–82.

64. T. Veruttipong, W. Imbriale, and D. Bathker, “Design and Performance Analysis 

the DSS-13 Beam Waveguide Antenna,” TDA Progress Report PR 42-10

March/April 1990 (15 May 1990), pp. 99–113. 

404

Uplink-Downlink: A History of the Deep Space Networ
65. S. D. Slobin, T. Y. Otoshi, M. J. Britcliffe, L. S. Alvarez, S. R. Stewart, and M. M

Franco, “Efficiency Calibration of the DSS 13 34-m Diameter Beam Wavegui

Antenna at 8.45 and 32 GHz,” TDA Progress Report PR 42-106, April-June 199

(15 August 1991), pp. 283–89.

66. M. S. Esquival, “Optimizing the G/T ratio of the DSS 13 34 m Beam Wavegui

Antenna,” TDA Progress Report PR 42-109 January-March 1992 (15 May 1992

pp. 152–61.

67. W. Imbriale, W. Veruttipong, T. Otoshi, and M. M. Franco, “Determining Noi

Temperature in Beam Waveguide Systems,” TDA Progress Report PR 42-11

October-December 1993 (15 February 1994), pp. 42–52. 

68. L. S. Alvarez, M. J. Britcliffe, M. M. Franco, S. R. Stewart, and H. J. Jackson, “Th

Efficiency Calibration of the DSS 24 34-Meter Diameter Beam Wavegui

Antenna,” TDA Progress Report PR 42-120 (15 February 1995), p. 174.

69. D. L. Ross, “DSCC Subsystem Functional Requirements; Telemetry Subsyste

1992–1995,” JPL Document D-6111, 824-35 (15 May 1989). 

70. J. Statman, G. Zimmerman, F. Pollara, and O. Collins, “A Long Constraint Leng

VLSI Viterbi Decoder for the DSN,” TDA Progress Report PR 42-95, Jul

September 1988 (15 November 1988), pp. 134–42.

71. C. R. Lahmeyer and K. M. Cheung, “Long Decoding Runs for Galil

Convolutional Codes,” TDA Progress Report PR 42-95, July-September 1988 (1

November 1988), pp. 143–52.

72. J. Statman, J. Rabkin, and B. Siev, “Big Viterbi Decoder Results for (7,1/

Convolutional Code,” TDA Progress Report PR 42-99, July-September 1989 (1

November 1989), pp. 122–23.

73. I. M. Onyszchuk, “Testing Interconnected VLSI Circuits in the Big Viter

Decoder,” TDA Progress Report PR 42-106, April-June 1991 (15 August 1991), p

175–82.

74. B. Falin, “DSCC Subsystem Functional Requirements: Command Subsyste

1992–1996,” JPL Document D-6395, 824-36 (1 August 1989). 

40

The Galileo Era: 1986–1996
75. Jet Propulsion Laboratory, “DSCC Subsystem Functional Requirements: DSC

Tracking Subsystem 1992–1996,” JPL Document D-7335, 824-38 (1 July 1990)

406

Uplink-Downlink: A History of the Deep Space Networ
Chapter 

The Cassini Era: 1996–1997

407
THE CASSINI ERA

Winds of Change

Throughout its life, the form of the DSN at any single point in time was shaped b

many forces acting on it simultaneously and often in different directions. These forc

included budget constraints from the NASA Office of Tracking and Data Acquisitio

(Code O), the requirements for support of new missions from the NASA Office 

Space Science (Code S), the drive of new technology, the pressure of real-time oper

tions, and the concerns of foreign agencies and competing requirements for limit

antenna time from radio astronomy and other space science constituencies. Dealing wi

these often conflicting currents had become a way of life at all levels within the DS

structure, and the remarkable progress recorded in the forthcoming pages attests to th

high degree of success that was achieved.

By 1995, however, the winds of change were blowing more strongly than ever befo

throughout NASA, and by 1997 their effect was being keenly felt in the DSN. Th

changes would affect the established purpose, scope, and functions of the DSN, an

408

Uplink-Downlink: A History of the Deep Space Networ

Figure 6-1. Cassini Era mission set, 1997.

Cassini Era Mission Set

Deep Space Missions (Launch) Earth-Orbiter Missions

Galileo (1989) ISTP-Soho

Voyager (1977) ISTP-Polar

Ulysses (1990) ISTP-Wind

Pioneer 10 (1972) ISTP-Geotail

N-E Asteroid Rndv. (2/17/96) IR Space Observatory

Mars Global Surveyor (11/7/97 ASTRO-D

Mars Pathfinder (12/04/96) TOMS-EP

Cassini (10/15/97) YOHKOH Solar-D

Space Tech. Res. Vehicle A

Radar Satellite

Roentgen Satellite

SURF Satellite-1

SSTI-Lewis

Hotbird-2,-3

HALCA
they first appeared in the Telecommunications and Mission Operations Directora

(TMOD) Implementation Plan for Fiscal Year 1998.1 This plan is discussed fully in 

later chapter.

This chapter will review the DSN and the missions it was supporting as the Galileo E

came to an end and the Cassini Era opened to an environment of change.

The Cassini Era Mission Set

A snapshot of the DSN operational tracking schedule in 1997 would have revealed th

portfolio of deep space and Earth-orbit missions shown in Figure 6-1. This represent

the DSN mission set for the first year or two of the Cassini Era. 

Except for Ulysses, which was an ESA mission, all of the deep space missions were 

NASA origin. Half of the missions, Galileo, Voyager, Ulysses, and Pioneer 10, were old

missions that had been in the DSN for many years and have been discussed in prev

ous chapters. The Near-Earth Asteroid Rendezvous, Mars Global Surveyor, Ma

Pathfinder, and Cassini missions were new in 1996 and 1997, and brought with the

new challenges and changes for the DSN. 

40

The Cassini Era: 1996–1997
DEEP SPACE MISSIONS

General

Through the end of the Galileo Era and the beginning of the Cassini Era, the ongoin

deep space missions, Galileo, Ulysses, Pioneer 10, and Voyagers 1 and 2, presented n

new challenges for the DSN. They continued to return science and engineering dat

each according to its own remaining capability, and were provided with minimal trac

ing station support, sufficient only to maintain their viability as scientific missions. Th

changes and upgrades that had been incorporated into the DSN since these missio

began had always maintained a capability to handle their diminishing requirements f

telecommunications and data acquisition support.

Galileo

Amongst the aging missions, Galileo was the most active. As described in the previo

chapter, Galileo had completed its primary mission in December 1997 and continu

at a much reduced pace to carry out further observations of Europa under the nam

Galileo Europa Mission. It remained entirely dependent upon arraying of the DSN 7

m/34-m antenna for its downlinks, since the Parkes antenna was no longer available 

support the arrayed configurations.

Ulysses

As the Ulysses spacecraft embarked on its second 6.2-year orbit over the poles of th

Sun, its science instruments continued to perform normally. The north and south pol

passes were planned for 2000 and 2001, respectively. On this orbit, the properties 

solar winds in high solar latitudes during the maximum of the solar activity cycle we

to be investigated. Through 1997, Earth-pointing maneuvers and instrument calibr

tions were made regularly, in preparation for observations during the fifth solar oppositio

in March 1998. Daily passes on the 34-m antennas at S-band or X-band, and telem

try running at 512 bits per second to 2,048 bits per second, were typical of this perio

Voyagers 1 and 2

The continuation of the Voyager 1 and 2 missions beyond the outer planets was call

the Voyager Interstellar Mission (VIM) and would continue through the year 201

Through 1996 and 1997, Voyager 1 and Voyager 2 maintained a presence on the DS

410

Uplink-Downlink: A History of the Deep Space Networ
tracking schedules with several passes per week for each spacecraft on the 34-m ante

nas, with occasional support on the 70-m antennas.

At approximately 2:10 p.m. Pacific time on 17 February 1998, according to VIM pro

ect manager Ed B. Massey, Voyager 1 reached an Earth-to-spacecraft range of 10.4 billio

km (6.5 billion miles), exceeding the record held by Pioneer 10 for 25 years, and becam

the most distant human-made object in space. Almost 70 times farther from the Su

than Earth (70 AU), with the radio signal taking 9 hours and 36 minutes to travel fro

the spacecraft to Earth, Voyager 1 was then at the very edge of the solar system. Th

downlink data rate was 160 bits per second or 600 bits per second on the 34-m ante

nas and could be increased to 1.4 kilobits per second on the 70-m antennas whe

required for tape recorder playback. At a smaller distance of 52 AU, Voyager 2 was bein

supported by the southern hemisphere stations in Canberra and could receive downlin

data at 7.2 kilobits per second.

JPL marked the event with a special press release,2 “Voyager 1 Now Most Distant Huma

Made Object In Space.” The article explained the scientific significance of this remarkab

achievement: 

Having completed their primary explorations, Voyager 1 and its twin Voyager 2

were studying the environment of space in the outer solar system. Although they

were beyond the orbit of all the planets, the spacecraft remained well within the

boundary of the Sun’s magnetic field, called the heliosphere. Science instruments

on both spacecraft sensed signals that scientists believed were coming from the

outermost edge of the heliosphere, known as the heliopause. The heliosphere results

from the Sun’s emission of a steady flow of electrically charged particles called the

solar wind. As the solar wind expands supersonically into space in all directions,

it creates a magnetized bubble—the heliosphere—around the Sun. Eventually, the

solar wind encounters the electrically charged particles and magnetic field in the

interstellar gas. In this zone, the solar wind abruptly slows down from supersonic to subsonic speed, creating a termination shock. Before the spacecraft travel

beyond the heliopause into interstellar space, they will pass through this termination shock. Dr. Edward C. Stone, Voyager project scientist and director of JPL,

said, “The data coming back from Voyager now suggest that we may pass through

the termination shock in the next three to five years. If that’s the case, then one

would expect that within ten years or so, we would actually be very close to penetrating the heliopause itself and entering into interstellar space for the first time.” 

41

The Cassini Era: 1996–1997
Reaching the termination shock and heliopause would be major milestones

for the mission because no spacecraft had been there before, and the Voyagers

would gather the first direct evidence of their structure. Encountering the termination shock and heliopause had been a long-sought goal for many space

scientists. Exactly where these two boundaries were located and what they were

like remained a mystery.

Although these were significant long-range telecommunications records for the DSN

uplink and downlink communications with both spacecraft remained routine matte

With plenty of performance margin still remaining, the DSN expected to be able 

support the VIM for the next twenty years.

Pioneer 10

After an active life of 25 years, the Pioneer 10 mission came to an end on 31 March 199

with the last track at DSS 63. Launched on 2 March 1972 and tracked by the DSN ev

since, Pioneer 10 support had almost become a permanent feature of routine DSN activ

ty. Although the downlink was still running at 8 bps, the signal was very weak, and it h

been determined that the science value of the data being returned was no longer sufficie

to justify further continuation of the mission. Pioneer operations had been conducted fro

the mission control center at the Ames Research Center in Sunnyvale, California, for man

years, and the mission had many notable scientific achievements to its credit. By 1983, 

had become the first spacecraft to travel beyond the orbits of Neptune and Pluto. Followin

a solar system escape trajectory away from the Sun, it continued to move further outwa

in search of the heliopause, the region of the solar system where the influence of the Su

itself finally ends and true interstellar space begins. Now, following a trajectory in the opp

site direction to that of Pioneer 10, the pursuit of that goal would be taken over by Voyag

In the immediate future, the Pioneer 10 spacecraft would be used by the DSN operatio

group at JPL to train new station controllers for future missions. 

Near-Earth Asteroid Rendezvous

The Near-Earth Asteroid Rendezvous (NEAR) mission was the first in NASA’s Discove

program of lower cost, highly focused planetary science missions. It was developed an

managed by the Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland

The primary objective of the NEAR mission was to inject a spacecraft into a 50-k

orbit around the near-Earth asteroid Eros for the purpose of making scientific observ

412

Uplink-Downlink: A History of the Deep Space Networ
tions to determine its size, shape, mass, density, and spin rate. It could also determin

the morphology and mineralogical composition of the surface.

Launched in February 1996, the NEAR mission used an Earth gravity-assist flyby 

early 1998 to deliver the spacecraft to the asteroid Eros in January 1999. Orbital ope

ations were to begin immediately following arrival and were planned to be about on

year in duration. In the early part of its mission, June 1997, NEAR flew by the aste

oid Mathilde. It found Mathilde to be composed of extremely dark material with numero

large impact craters, including one nearly six miles deep. 

DSN support for the NEAR mission in 1996 and 1997 was conducted primarily o

the 34-m HEF or BWG antennas, and the X-band uplinks and downlinks carryin

telemetry, command, and ranging data were well within existing capabilities. Initial acqu

sition and a trajectory correction maneuver in March 1997 were accomplished by th

DSN without incident. 

During the critical phases of the mission and mission operations at Eros, NEAR requir

continuous tracking support (three 8-hour passes per day) from the 34-m stations, wi

occasional use of the 70-m antennas. At other periods during the cruise phase, the trac

ing support was reduced to one or two passes per day.

In preparation for an Earth swing-by maneuver in early 1998, tracking support f

NEAR was increased to the level of three passes per day in December 1997.

Mars Global Surveyor

Mars Global Surveyor (MGS) was the first mission in a new program of Mars expl

ration called the Mars Surveyor Program. It was also the first of NASA’s new “fast

better, cheaper” family of missions. MGS was designed to deliver a single spacecraft 

Mars for an extended orbital study of the surface, atmosphere, and gravitational an

magnetic fields of the planet. A search for gravitational waves and a demonstration 

Ka-band downlink communications technology was to be conducted during the flig

to Mars. The spacecraft was to be launched during the November 1996 Mars oppo

tunity, using a Delta launch vehicle with a PAM D upper stage. The transit time 

Mars would be about ten months. MGS was to be the first U.S. spacecraft to orb

Mars since the Viking Orbiters twenty years before and the first to use aerobrakin

rather than propulsive maneuvers to adjust its orbit upon arrival. The use of aerobra

ing techniques had been demonstrated in mid-1993 during the final stages of the Magella

mission to Venus and was considered to be a promising technique for reducing th

41

The Cassini Era: 1996–1997
spacecraft fuel expended in circularizing the spacecraft orbit around a planet. Repetiti

observations of the Mars surface and atmosphere were to be carried out from a near

circular, low-altitude (378 km) orbit over a period of one Martian year (687 Earth day

An overview of the major components of the spacecraft is shown in Figure 6-2.

Like the earlier Mars Observer spacecraft, MGS uplinks and downlinks were both on X

band, and it also carried a Ka-band downlink beacon as a new downlink technolo

demonstration. The downlink telemetry would employ Reed-Solomon and convolution

(K = 7, R = 1/2) encoding and would range from 10 bits per second to 32 kilobits p

second for engineering data, and 4 kilosymbols per second to 85 kilosymbols per se

ond for Reed-Solomon encoded science data. In coding terminology, a symbol is essential

a Reed-Solomon encoded data bit. The MGS spacecraft transmitted 250 encoded b

to represent every 218 bits of its raw science data, a ratio of 1.147 to 1.0. 

414

Uplink-Downlink: A History of the Deep Space Networ

Figure 6-2. Mars Global Surveyor spacecraft in mapping configuration. The spacecraft w

built and operated by Lockheed Martin Astronautics, JPL’s industrial partner on the mission, 

Denver, Colorado.

Solar

Array

Propulsion

Module

Main

Engine

AACS Thruster

1 of 4

Solar

Array

High Gain Antenna

+Z

+Y

Nadir Deck

Equipment

Module

Drag

Drag Flap

Flap
The command uplink would operate at a nominal rate of 125 bits per second, althoug

several other rates were available. Radio metric data consisting of two-way Doppler an

sequential ranging data would be generated from the coherent X-band uplink and dow

link carriers, and a noncoherent signal from the spacecraft’s ultra-stable oscillator (USO

would be used to generate project data during the frequent occultation experiments.

The MGS mission required the tracking stations to be able to acquire the X-band dow

link and achieve telemetry “in-lock” within five minutes of spacecraft view at the statio

for data rates of 18.6 ksps or greater. Reacquisition of the telemetry signal following ea

Earth occultation during the mapping phase was to be accomplished within one minu

of spacecraft view. These requirements, which posed some problems for the DSN, cou

not be solved before launch but were satisfied by the time the spacecraft reached Mar

The DSN was required to deliver at least 95 percent of the science data transmitt

from the spacecraft during the mapping phase to the Advanced Multimission Operatio

System (AMMOS) at JPL. Because the Mars Orbiter camera instrument made exte

sive use of data compression, the imaging science data could not tolerate significant ga

in the “packets” of telemetry data delivered by the DSN. This produced a further requir

ment on the DSN to deliver science data “packets” containing no more than one pack

gap or error within 10,000 packets. This was equivalent to one error per 100 millio

bits (1 x 10-8) and would require some additional backup recording equipment in th

GCF to meet the stringent requirement.

Following initial acquisition of the downlink signal after launch by the 26-m antenn

at Canberra, the mission was to be supported by the 34-m HEF antennas, DSS 15, 4

and 65. The 34-m BWG antennas would also provide support as they became availab

in 1997. The 70-m antennas were to support the critical Mars Orbit Insertion sequen

and to be available to support any other situations which were declared to be “critica

by the MGS flight operations manager.

DSN readiness to support the launch and cruise phase of the MGS mission was pr

sented to a Telecommunications and Mission Operations Directorate (TMOD) Revie

Board in October 1996. For the first time, it was part of a broad-based review whi

included DSN and AMMOS as an integrated service of the TMOD. It was this int

grated service (which included its multimission operators) that would be used by th

MGS flight operations manager to conduct the mission after launch.

The DSN presentation satisfied the Review Board that it had verified telecommunic

tions compatibility with the spacecraft, had adequately trained its operations personn

41

The Cassini Era: 1996–1997
had developed an Initial Acquisition Plan covering all available launch windows, an

that all of the facilities necessary for launch and early cruise were in place. The uplin

and downlink requirements for MGS were well within the capabilities of the DSN sy

tems that had been implemented earlier under the SPC upgrade program. Because th

issues of downlink acquisition time and telemetry data accountability were related 

operations at Mars, they were not included in this review. The DSN, together wi

AMMOS, was ready to support the MGS launch.

At noon on 7 November 1996, Mars Global Surveyor lifted off launch pad 17A at Ca

Canaveral Air Station, Florida, on a three-stage Delta II launch vehicle bound for Mars. A

launch vehicle sequences were completed as planned and ended with separation from th

spacecraft about 50 minutes after launch. An anomaly that occurred during deployment 

the spacecraft solar panels was not a cause for concern at the time, since it was believed 

could be corrected the following day. About 70 minutes after launch, just after the spac

craft came in view of Canberra, the X-band downlink was very quickly acquired, first b

the 26-m antenna (DSS 46), and then by the 34-m HEF (DSS 45), using the offsets fro

DSS 46. The DSN settled into routine operations as MGS cruise support began. 

Over the next several weeks, spacecraft engineers continued to evaluate various solutio

to the problem created by the solar array anomaly, although it posed no immedia

threat to the mission. 

In January 1997, the spacecraft was turned to point its high-gain antenna toward Eart

and with a stronger downlink available, the spacecraft immediately began transmittin

telemetry at the higher data rates. During a period of low activity in May, a progra

of observations directed to the search for gravitational waves was carried out. This w

the long-awaited opportunity that had eluded the project investigators when the Galil

X-band mission failed. The high-stability X-band exciter and X-band uplink and dow

link were key factors in reaching the sensitivity needed to detect the presence of gravi

waves by their characteristic three-perturbation signature in the two-way Doppler dat

There was no immediate answer to whether the observations revealed the presence 

gravitational waves, since analyses of these data would take many months to complet

Ka-band technology demonstration passes with DSS 15 and DSS 13 were conduct

over a two-week period beginning on 21 July. The Ka-band downlink was received 

DSS 13 in a coherent mode with the X-band uplink from DSS 15. After a period 

good ranging data had been recorded, DSS 15 transferred its uplink to DSS 34 to ge

erate comparative data over the Goldstone/Australia path. 

416

Uplink-Downlink: A History of the Deep Space Networ
In July, with the spacecraft rapidly approaching Mars, mission controllers and DSN ope

ators engaged in several simulation exercises to prepare for orbital operations. Durin

the simulations, the spacecraft radio transmitter was turned on and off over the cour

of a six-hour period to simulate three actual orbits. Because capturing the project da

and acquiring the telemetry data under these rapidly changing conditions would be a

operationally demanding task for the tracking station operators and project team, the

simulations were used to familiarize them with the necessary operational procedures. 

About three weeks before the actual MOI, the DSN team reviewed its state of read

ness to support the rapidly approaching orbit insertion and orbital operations phase 

the MGS mission. As in the Launch Readiness Review, the review included the stat

of the AMMOS as well as that of the DSN.

The DSN team presentation focused on the steps that had been taken to meet th

telemetry delivery (data gaps) and acquisition (lock-up time) requirements that had bee

of concern to the DSN prior to launch. It was shown that the implementation of re

able network servers in the GCF and the correction of a known antenna-pointing anoma

at the BWG stations had accounted for most of the difference between actual measur

performance of the DSN and the performance required by the MGS specifications. Th

remaining errors would be attributable to data gaps induced by downlink data ra

changes on the spacecraft. Although lab measurements at JPL and past performance 

the stations confirmed that telemetry lock-up time would meet the requirement, som

uncertainty remained until the actual downlink became available and performance w

verified under fully operational conditions. An operations support plan for the MO

sequence; availability of the necessary antennas, communications, and facilities; and 

demonstrated level of crew training completed the DSN presentation. There were n

outstanding issues or concerns. The DSN’s Telecommunications and Mission Servic

(TMS) manager, John C. McKinney, assessed the status as Network-ready to suppo

the Mars Orbit Insertion and Aerobraking events.

The DSN configuration used to support Mars Global Surveyor orbit insertion and orbit

operations is shown in Figure 6-3.

The spacecraft executed the orbit insertion sequence perfectly, beginning with a 2

minute retro-engine burn on 11 September 1997, during the mutual view period 

Canberra and Madrid. Twelve minutes after the start of the engine burn, the first Ma

occultation occurred, providing the tracking station operators with their first opport

nity to demonstrate the benefits of the simulated acquisition training. When the spacecra

emerged from behind the planet four minutes after the retro-engine burn had been com

41

The Cassini Era: 1996–1997
418

Uplink-Downlink: A History of the Deep Space Networ

Figure 6-3. DSN configuration for Mars Global Surveyor. This was the standard DSN configuration for the Cassini Era and has been discussed earlier as part of the SPC upgrade task. It was used in various forms for all the missions in 1996 and 1997. 

70 Meter Antenna

34M HEF/BWG

X band

Transmitter

X band

Exciter SRA

Command

Matrix

Switch

Differential

Interface

Assembly

Command

Modulator

Assembly

Command

Processor

Assembly

From BVRFrom BVR

From BVR

LNA

X-band

MASER

BVR

LCCD SSK MCD2 FS RS

Sequential RangingAssembly (SRA)

TGC/TCA

DM

Bridge

Router

To/From JPL

DSCC

Monito & Control

(DMC)

SYMBOL

STREAM

DIST.

(SSD)

RCP

DSP-R

ICA

IF

Channel

Assy. (ICA)

BLOCK V RECEIVER

(BVR)

RF/IF

Down

conv.

RHCP

LHCP

Metric

Data Assy.

(MDA)

LNA

X band

MASER

Receiver

Control

Computer

(RCC)

Receiver

Channel

Processor

(RCP)

Telemetry

T

Processors(LCCD)

elemetry Processors

Level Converter & Clock Dist.(LCCD) Assy.

Telemetry

Command

Radiometric

Monitor

Station

Comm

Processor

(SCP)

LEGEND

SSK = Soft Symbol CombinerMCD = Maximum Likelyhood

Convolutional Decoder

FS = Frame SynchronizerRS = Reed-SolomonDM = Data Mover

Reliable

Network

Server

(RNS)

LCCD SSK MCD2 FS RS

TELEMETRY CHANNEL ASSEMBLY (TCA) 1

TELEMETRY CHANNEL ASSEMBLY (TCA) 2

Telemetry Group Controller

DM

DSCC

Spectrum Processor

Radio Science

(DSP-R)
pleted, the downlink was acquired within seconds. Doppler data indicated that the spac

craft had entered a highly elliptical orbit within one minute of the intended 45-ho

orbit. The spacecraft was about 250 km above the Martian surface (periapsis) and abo

56,000 km above the surface at the farthest point (apoapsis).

A few days after the spacecraft began orbiting the planet, the spacecraft magnetomet

detected the existence of a planet-wide magnetic field. This discovery was hailed by Vi

President Gore as “another example of how NASA’s commitment to faster, better, chea

er Mars exploration is going to answer many fundamental questions about the histo

and environment of our neighboring planet.” 

The first aerobraking maneuvers began with retro-engine burns at apoapsis on 1

20, 22, and 24 September. As each periapsis passage began to take the spacecraft in

the upper reaches of the Mars atmosphere, atmospheric drag provided additional ae

obraking effect. While the orbit slowly decreased, data taking progressed to the poi

where the MGS Science Team was able to hold a press conference at JPL on 

October to report their findings from all six science experiments. “The spacecraft an

science instruments are operating magnificently,” reported Dr. Arden Albee, the MG

project scientist at the California Institute of Technology, Pasadena, California. “Th

initial science data we’ve obtained from the walk-in phase of aerobraking are remar

able in their clarity, and the combined measurements from all of the instrumen

over the next two years are going to provide us with a fascinating new global vie

of the planet.”

Suddenly, during the fifteenth periapsis passage on 6 October, significant movement w

observed in the damaged solar array panel. On 12 October the orbit was temporari

raised to reduce the stress on the solar panel at each periapsis passage while the oper

tions teams at JPL and Lockheed Martin Astronautics investigated this potentially alarmin

situation. Two weeks later, with the spacecraft in a 35-hour orbit and closest approa

to the surface of 172 km, aerobraking was resumed at a much slower rate than befo

to avoid putting undue stress on the unlatched solar panel. This decision would exten

the aerobraking phase by eight to twelve months and would change the final mappin

orbit. However, it would not significantly affect the ability of MGS to accomplish 

primary mission’s science objectives.

Apart from the faulty solar panel, the spacecraft was operating perfectly, and with DS

support available from the BWG antennas, science data collection continued unabate

An image of the giant volcano Olympus Mons taken during this period is shown 

Figure 6-4.

41

The Cassini Era: 1996–1997
MGS completed its 100th orbit around Mars in January 1998. Assisted by the cal

state of the Martian atmosphere, aerobraking operations were proceeding satisfactori

The spacecraft had reached a 19-hour orbit around the planet, with a high point 

about 28,000 km and a low point of about 120 km.

The target date for the start of mapping operations was March 1999, and it was hop

that the duration of the mapping phase would still be one Martian year. The DSN w

providing support with the 34-m HEF antennas on a routine basis with typical dow

link data rates of 2,000 bits per second for engineering and 21,333 symbols per secon

for playback of science data.4

420

Uplink-Downlink: A History of the Deep Space Networ

Figure 6-4. Mars Global Surveyor image of Olympus Mons. Mars Global Surveyor obtain

this spectacular wide-angle view of Olympus Mons from an altitude of 900 km (500 mi) abo

the surface on its 263rd orbit around the planet on 25 April 1998. More than three times t

height of Mt. Everest, this giant volcano is almost flat, with its flanks having a gentle slope 

three to five degrees.
Mars Pathfinder

About one month after Mars Global Surveyor lifted off the launch pad at Canaveral A

Force Station bound for Mars, the second spacecraft in the Mars Discovery Progra

was launched from the same pad with the same destination, but with a different obje

tive. Mars Pathfinder (MPF) was primarily an engineering demonstration of k

technologies and concepts for eventual use in future missions to Mars employing sc

entific Landers. MPF also delivered a scientific instrument package to the surface 

Mars to investigate the elemental composition of Martian rocks and soil and the stru

ture of the Mars atmosphere, surface meteorology, and geology. In addition, MPF carri

a free-ranging surface Rover, which was deployed from the Lander to conduct techno

ogy experiments and to serve as an instrument deployment mechanism. At launch, th

mass of MPF was 890 kilograms, compared to 1,060 kilograms for MGS. MPF wou

arrive at Mars on 4 July 1997, seven months after launch, compared to 11 Septemb

1997, ten months after launch, for MGS.

The MPF spacecraft comprised three major elements: the cruise vehicle, the deceler

tion systems, and the Lander vehicle that contained the Rover.5

The cruise vehicle provided the major spacecraft functions of power generation, propu

sion, and attitude control prior to entry into the Martian atmosphere. The deceleratio

subsystem comprised an aeroshell, parachute, tether, retrorockets and inflatable airbag

The tetrahedral Lander structure enclosed the science instruments, the Rover, and th

engineering subsystems necessary for cruise and surface operations. The radio transpo

der and transmitter, along with attitude control and data handling electronics and softwar

were also located on the Lander and were connected to the cruise stage via a detac

able cable harness. The Lander structure was self-righting, with three side petals th

opened to establish an upright configuration on the surface from which the Rover cou

be deployed. Power was provided by solar arrays mounted on the surface panels. 

The MPF Lander with the Rover vehicle in a deployed configuration on the Mars su

face is depicted in Figure 6-5.

The duration of the primary mission was defined to be 30 days beginning at the tim

of landing. Pathfinder requirements for tracking and data acquisition lay within curre

(1997) DSN capabilities, and the Telecommunicatons and Mission Services (TMS) ma

ager Dennis M. Enari concluded that no special implementation was needed. Both uplin

and downlink for MPF were on X-band and would be used for command, telemetr

and generation of radio metric Doppler and range data. There were no requirements f

42

The Cassini Era: 1996–1997
project observations, although the DSCC project equipment would be used to reco

open-loop spectral data from the X-band downlink during the rapid and critical entr

descent, and landing sequence. Descent Doppler profiles and key engineering telemet

data would be reconstructed from this data after the event. Telemetry data rates wou

range from 40 bits per second in the cruise phase to 22,120 bits per second during su

face operations. All data would be convolutionally coded at either (R = 7, K = 1/2) 

(R = 15, K = 1/6). There would be no uncoded data. Command data rates rangin

from 7 to 500 bits per second would be used on the X-band uplink. 

During the entry, descent, and landing phase, both the 70-m and the 34-m HEF ante

nas at Madrid would be tracking the MPF spacecraft simultaneously. At other time

the tracking support would be provided by the 34-m HEF and 34-m BWG antenna

with occasional use of the 70-m antennas for the downlink only. The 26-m antenn

at DSS 46 and DSS 16 would provide support for the initial acquisition events only

422

Uplink-Downlink: A History of the Deep Space Networ

Figure 6-5. Pathfinder Lander deployed on the surface of Mars. 

Thermocouples

Wind Socks

Wind Sensor

Mars Pathfinder lander

Solar Panel

Low-Gain

Antenna

ASI/MET

Accelerometers

Rover

Solar Panel

Alpha Proton

X-ray Spectrometer

Instrument Electronics

Assemblies Solar Panel

High-Gain

Antenna

Imager for Mars

Pathfinder (IMP)

Atmospheric Structure Instrument

and Meteorology Package

(ASI/MET)
Mars Pathfinder blasted into space on 4 December 1996, the third day of its laun

window. The launch, ascent, orbital injection, and spacecraft separation events were 

normal. About 70 minutes after lift-off, the spacecraft made its first appearance over th

Goldstone radio horizon. Stations DSS 16 and DSS 15 quickly locked up their receive

on the downlink signal and, less than two minutes later, began flowing telemetry da

to the mission controllers at JPL. On the evidence of these data, the spacecraft tea

reported that all critical spacecraft systems, such as power, temperature, and attitude co

trol, were performing well. “Everything looks really good and we’re very happy,” sa

Tony Spear, Pathfinder project manager at NASA’s Jet Propulsion Laboratory.

An event of some significance to the DSN occurred on 18 January 1997 when the ne

Block 3 Maximum Likelihood Decoder (MCD3) was used for the first time to proce

live inflight data from DSS 15 Goldstone. 

The MCD3 grew out of the technology that had been used by Statman in developin

the Big Viterbi Decoder for the original Galileo X-band mission in 1989. Although th

effort was dropped when the spacecraft high-gain antenna problem forced a redesign 

the Galileo mission in 1991, the enhancement in downlink performance available fro

newer, more powerful convolutional codes remained viable. Although the encoding proce

in the spacecraft was a relatively simple process, the new codes required much bigg

and extremely complex decoders in the DSN to take advantage of the improvement 

performance. In the intervening years, DSN engineers had pursued the development 

such a machine and, by the time of the MPF mission, were ready to demonstrate th

first machine of its kind in a real, inflight situation. 

In this demonstration, the MPF telemetry downlink consisted of a convolutionally cod

(R = 15, K = 1/6) data stream, running at 4,070 bits per second. In light of the impo

tance of this machine to later MGS, MPF, and Cassini mission support, its first successf

demonstration under operational conditions was a matter of considerable satisfaction 

the DSN. 

The cruise phase passed quietly without the occurrence of any significant inciden

Spacecraft and science instrument status checks were made routinely, and several traje

tory correction maneuvers were successfully executed. The DSN operations team carri

out several rehearsals to improve proficiency in the procedures that would be used 

July for the entry, descent, and landing sequence in July.

On 30 June, with all spacecraft systems in excellent operating condition and com

manded by a sequence from its onboard computer, the MPF spacecraft began th

42

The Cassini Era: 1996–1997
entry, descent, and landing phase of its mission. On the morning of 4 July, an upda

of the MPF orbit based on the latest DSN Doppler and range data indicated th

MPF was heading straight for the center of its predetermined 60-mile by 120-m

landing ellipse and would enter the upper atmosphere at an entry angle just 0.7

degrees less than its original design value of 14.2 degrees. A few hours later, at 10:07:2

a.m. Pacific time, 4 July 1997, the MPF spacecraft landed successfully on the surfa

of Mars, marking NASA’s return to the surface of the Red Planet after more tha

twenty years. A low-power transmission from an independent antenna on one of th

petals confirmed the landing and indicated that the craft had landed on its base pet

in an upright position.

The first low-gain antenna transmission was received on schedule about four hours lat

It contained preliminary information about the health of the Lander and Rover; the o

entation of the spacecraft on the surface; the entry, descent, and landing; and th

temperature and density of the Martian atmosphere. This was soon followed by a hig

gain antenna transmission which contained the first images from the Lander. The ne

day, 5 July, after clearing a problem with the petal that the Rover needed as a ramp 

reach the surface and rectifying a Rover-to-Lander communication link problem, th

mission control team moved the Rover vehicle (named Sojourner) down the ramp und

its own power and onto the Martian soil. Images of the Rover from the Lander an

vice versa, plus engineering data from both, confirmed that both vehicles were in the

proper positions and in good operating condition. With the downlink telemetry da

rate set to 6,300 bps, science activities from the surface began in earnest.

During the first two weeks of surface operations, uplink and downlink communicatio

were interrupted several times due to Lander computer resets that unexpectedly switch

the low-gain and high-gain antennas, and to operational errors related to the timing 

the limited duration downlink sessions. Once these initial problems were cleared up, th

data rate was raised to 8,300 bps and the return of high-quality data from the MP

Lander became a matter of routine operation for the DSN. Downlink sessions with th

Lander were of short duration, generally about ninety minutes, during which about 6

megabits of science and engineering data were returned. By the time MPF had com

pleted its primary 30-day mission on 3 August, it had returned 1.2 gigabits of dat

including 9,669 images of the Martian landscape.

The designers of the spacecraft and the mission had every reason to be proud of the

efforts. “This mission demonstrated a reliable and low-cost system for placing scien

payloads on the surface of Mars,” said Brian Muirhead, Mars Pathfinder project ma

ager at JPL. “We’ve validated NASA’s commitment to low-cost planetary exploratio

424

Uplink-Downlink: A History of the Deep Space Networ
shown the usefulness of sending microrovers to explore Mars, and obtained significa

science data to help understand the structure and meteorology of the Martian atmo

phere, and to understand the composition of the Martian rocks and soil.”

The downlink telemetry data from Mars, delivered by the DSN stations to JPL in re

time were subsequently processed into images by the MPF scientists and made availab

to the media and on the World Wide Web. The images returned from both Lander an

Rover were remarkable indeed, but it was the robust, semi-autonomous Rover, Sojourn

that captured the imagination of the public. To accommodate the swell of public inte

est in following the mission via the World Wide Web, JPL engineers, in cooperatio

with several educational and commercial institutions, constructed twenty Pathfinder m

ror sites. Together, these MPF sites recorded 565,902,373 hits worldwide during th

period 1 July–4 August. The highest number occurred on 8 July, when a record 47 m

lion hits were logged, more than twice the number received by the official Web site f

the 1996 Olympic Games in Atlanta, Georgia.

42

The Cassini Era: 1996–1997

Figure 6-6. The MPF Lander camera views the Sojourner Rover in operation near Yogi Ro

on the surface of Mars, July 1997.
A typical high-quality MPF image transmitted from Mars to Earth over the DSN telem

try downlink is shown in Figure 6-6. The inherent capability of the DSN downlin

contributed to the remarkable detail observed in this and other MPF images.

Downlink communications with the Lander continued with no sign of trouble until 2

September, when DSS 15 at Goldstone was unable to detect the presence of a dow

link at the scheduled transmission time. Declaration of a spacecraft emergency by th

Pathfinder mission director authorized Enari to negotiate the release of the 70-m ante

nas from Galileo and MGS support to assist with DSN attempts to recover the MP

downlink. At the time, it was surmised that the downlink problems were most like

related to depletion of the spacecraft battery and uncertainties in the status of the onboa

clock. While the spacecraft team investigated various scenarios to explain what mig

have happened to the spacecraft, the DSN went into emergency mode on a daily ba

for all MPF passes.

While these downlink recovery efforts were going on, however, there was a great de

of excitement in the science community as the scientific results of the mission becam

available. A press release on 9 October 1997 reported that “Mars was appearing mo

like a planet that was very Earth-like in its infancy, with weathering processes and flow

ing water that created a variety of rock types, and a warmer atmosphere that generat

clouds, winds, and seasonal cycles.”

At an 8 October 1997 press briefing at JPL, Mars Pathfinder project scientist Dr. Matthe

Golombek observed, “What the data are telling us is that the planet appears to ha

water-worn rock conglomerates, sand, and surface features that were created by liqu

water. If,” he added, “with more study, these rocks turn out to be made of composi

materials, that would have required liquid water flowing on the surface to round th

edges in pebbles we see on the surface or explain how they were embedded in larg

rocks. That would be a very important finding.”

Golombek also stressed the amount of differentiation—or heating, cooling, and rec

cling of crustal materials—that appeared to have taken place on Mars. “We’re seeing 

much greater degree of differentiation—the process by which heavier elements sink 

the center of the planet while lighter elements rise to the surface—than we previous

thought, and very clear evidence that liquid water was stable at one time in Mars’

past. Water, of course, is the very ingredient that is necessary to support life,” he adde

“and that leads to the $64,000 question: Are we alone in the universe? Did life ev

develop on Mars? If so, what happened to it and, if not, why not?” 

426

Uplink-Downlink: A History of the Deep Space Networ
Despite the most intense efforts by the DSN and spacecraft controllers to detect th

presence of a downlink, however weak or off-frequency it may have been, no downlin

could be found. There was conjecture that, without the heat generated by the batter

powered transmissions, the spacecraft temperature would fall below its operating lim

and the spacecraft computer that controlled the spacecraft transmission times would n

longer operate correctly. Whatever the cause, the downlink was never recovered, and fu

ther efforts were discontinued in mid-October.

At the time of the last downlink, the Lander had operated for nearly 3 times its desig

lifetime of 30 days, and the Sojourner Rover had operated for 12 times its design lif

time of 7 days. After the 4 July landing, it returned 2.6 billion bits of data, whi

included more than 16,000 images from the Lander and 550 images from the Rov

as well as more than 15 chemical analyses of rocks and extensive data on winds an

other weather factors. All MPF requirements of the DSN for telecommunications an

data acquisition support had been fulfilled.

The cost of designing and building the Pathfinder had been $171 million; that of th

Sojourner Rover, $25 million. Together, their combined costs would have been a me

round-off error in the $3 billion (1997 dollars) cost of NASA’s previous mission to Ma

the Viking Landers in 1976. In that sense, the MPF mission had accomplished one 

its primary objectives. As Brian Muirhead, Mars Pathfinder project manager at JP

declared at the end of the mission, “This mission has demonstrated a reliable and low

cost system for placing science payloads on the surface of Mars. We’ve validated NASA

commitment to low-cost planetary exploration.” 

NASA seemed well satisfied. A few weeks later, NASA Administrator Daniel S. Gold

recognized the efforts of all involved with the mission in a formal press release: “I wa

to thank the many talented men and women at NASA for making the mission such 

phenomenal success. It embodies the spirit of NASA and serves as a model for futu

missions that are faster, better, and cheaper. Today, NASA’s Pathfinder team should ta

a bow, because America is giving them a standing ovation for a stellar performance.” 

At the same time that it was dealing with the highly visible Mars Pathfinder even

described above, the DSN was also handling the arrival and aerobraking maneuvers 

the Mars Global Surveyor and arrayed operations for the Galileo encounter with th

Jupiter satellite Callisto. While these dramatic events were unfolding at JPL and aroun

the Network, another deep space mission was being readied for launch at Cape Canaver

The Cassini Saturn Orbiter with the Huygens Titan Probe had been successfully mat

42

The Cassini Era: 1996–1997
with the Titan IV/Centaur at the Cape Canaveral Air Force Station, and launch w

planned for 13 October. 

Cassini

The Cassini mission to Saturn and Titan was a cooperative endeavor by NASA, th

European Space Agency (ESA), and the Italian Space Agency (ASI). Its genesis can 

traced to the early 1980s, when the international science community agreed upon 

combined Saturn Orbiter/Titan Probe mission as the next logical step in the exploratio

of the solar system, following the Galileo mission to Jupiter. It was seen as a follow-o

mission to the brief reconnaissance of Saturn, which had been carried out by the Pione

11 spacecraft in 1979 and the Voyager 1 and 2 encounters of 1980 and 1981. It wou

be an enterprise that would span nearly thirty years from its initial vision to its com

pletion in the year 2008.

The Cassini mission was designed to make a detailed scientific study of Saturn; its i

moons, magnetosphere, and rings; and the satellite Titan. Observations relative to th

first four science objectives were to be made by twelve science instruments carried o

an orbiting spacecraft (Cassini). The Titan observations would be made by six scien

instruments onboard a probe (Huygens), which would be carried to the vicinity of Satu

by Cassini before being released to descend to the surface of the satellite. In addition 

these experiments, the DSN Project System would be used to conduct at least thr

gravitational wave searches en route to Saturn and to carry out numerous occultatio

experiments with the planet, moons, and rings during the orbital phase of the missio

Scheduled for launch in October 1997 using a Titan IV/Centaur launch vehicle, th

spacecraft would require a unique set of four gravity-assist maneuvers to arrive at Satu

almost seven years later, in July 2004. The gravity-assists would be provided by clo

flybys of Venus in April 1998 and June 1999. It would then fly by Earth in Augu

1999 and Jupiter in December 2000. The Cassini interplanetary trajectory with the fo

gravity-assist maneuvers is shown in Figure 6-7.

To reduce costs, the development of many mission operations capabilities was deferr

until after launch. Except for the three gravitational wave experiments, there were n

plans to acquire science data during the cruise phase or gravity-assist maneuvers. Spacecra

operations during the interplanetary cruise would be centralized at JPL. During th

orbital phase of the mission, a system of distributed science operations would allow sc

entists to operate their instruments from their home institutions with the minimu

interaction necessary to collect their data.

428

Uplink-Downlink: A History of the Deep Space Networ
Cassini was a three-axis-stabilized spacecraft, the main body of which was formed by 

stack consisting of a lower equipment module, a propulsion module, an upper equi

ment module, and the HGA. The various science instruments were mounted on palle

and, together with the Huygens Probe and RTGs, were attached to the stack at appr

priate points. The spacecraft contained twelve engineering subsystems in addition to 

complement of twelve science instruments.

At launch, the combined weight of Cassini, the Huygens Probe, fuel, and the laun

vehicle adaptor was 5,712 kilograms, making it the heaviest interplanetary spacecra

ever launched by NASA. More than half of the launch weight was contributed by th

propellant needed for the 94-minute main engine burn that would inject Cassini in

Saturn orbit. The spacecraft stood 6.8 meters high, with a maximum diameter of 

meters due to the HGA. The major components of the spacecraft are identified in th

diagram shown in Figure 6-8.

The design of the Cassini spacecraft was the end result of extensive tradeoff studies th

considered cost, mass, reliability, the availability of hardware, and past experience. Movin

parts were eliminated from the spacecraft wherever possible. Science instruments an

the high-gain antenna, which replaced the deployable type of antenna used on Galile

were permanently attached to the spacecraft, their pointing functions performed b

rotation of the entire spacecraft. Tape recorders were replaced with solid-state recorde

42

The Cassini Era: 1996–1997

Figure 6-7. Cassini interplanetary trajectory.

Venus Swingby

23 June 1999

Venus Swingby

25 April 1998

Earth Swingby

17 Aug 1999

Sun

Launch

6 Oct 1997

Interplanetary Trajectory

Deep Space

Maneuver

20 Jan 1999

Jupiter Swingby

30 Dec 2000

Saturn Arrival

1 July 2004
and mechanical gyroscopes were replaced with hemispherical resonator gyros. The hig

gain antenna would be used for the short-duration (2.5 hours), S-band radio-relay lin

between Cassini and the Huygens Probe, as well as for the permanent radio link betwee

Cassini and Earth.

Uplink and downlink communications on X-band were provided by the Radio Frequen

Subsystem. A Radio Frequency Instrument Subsystem provided unmodulated RF car

ers on the Ka-band and S-band for project experiments only during the cruise and orbit

phases. The X-band uplink carried command data in the range 7.8 bps to 500 bps an

sequential ranging modulation. The Ka-band uplink was unmodulated. Both Rad

Frequency Subsystems included redundant Deep Space Transponders (DSTs). Original

developed as a joint DSN/Flight project task at JPL in 1990 for use on X-band on

the DST was first flown on the NEAR and Mars Pathfinder spacecraft in 1996.6 It w

430

Uplink-Downlink: A History of the Deep Space Networ

Figure 6-8. Cassini spacecraft with Huygens Probe.

High-Gain

Antenna

Magnetometer

Boom

Radio/Plasma

Wave Subsystem

Antenna (1 of 3)

Remote

Sensing Pallet

445-newton Engine

(1 of 2)

Radioisotope

Thermoelectric

Generator

(1 of 3)

Cassini spacecraft

Huygens

Titan

Probe

Fields

and

Particles

Pallet

Radar Bay

Low-Gain

Antenna

(1 of 2)
later upgraded to include Ka-band and was flown for the first time in that configur

tion on Cassini.

7

The X-band downlink carried telemetry data with a wide range of data rates, from 

bps to 249 kilobits per second. The telemetry data was encoded with Reed-Solomo

(255, 223) coding concatenated with Viterbi (7, 1/2) or (15, 1/6) coding prior to tran

mission. It could also be transmitted in uncoded form. In addition to telemetry, th

downlink carried ranging modulation. 

The versatile design of the DST provided X-band, Ka-band and S-band downlinks th

could be either coherent or noncoherent with the X-band uplink. The Ka-band dow

link could be coherent with, or noncoherent with, the Ka-band uplink. This allow

the downlinks to be optimized for the various project investigations under a wide ran

of conditions.

The Antenna Subsystem included the 4-meter-diameter, narrow-beam-width HGA th

was designed for transmitting and receiving on all four communication bands, and tw

wide-beam-width, low-gain antennas that could receive and transmit on X-band only

Working with Cassini mission designers, the Telecommunications and Mission Servic

(TMS) manager, Ronald L. Gillette, negotiated tracking and data acquisition services f

the mission that generally fell within the existing (1997) or planned (2002) capability 

the Network. The 70-m, 34-m BWG, and 34-m HEF subnets would be required sing

or arrayed at various times during the mission. The initial acquisition and early crui

requirements, when the spacecraft would be using its low-gain antennas, would be m

without the need for any new implementation. By 2001, however, the 20-kW X-ban

uplinks on the 34-m HEF antennas would not provide adequate uplink margin for com

manding and X-band transmitters, and exciters would be needed on the three 70-

antennas. The DSN agreed to provide this new capability. The DSN also agreed to pr

vide a Ka-band uplink and downlink at DSS 25 for the project experiments, particular

the first gravitational wave experiment of 40 days’ duration in 2001. Where the resear

and development installation at DSS 13 had been equipped with an 80-watt transm

ter, this first fully operational Ka-band capability in the Network would have a 4-kW

transmitter and provide simultaneous X-band and Ka-band downlink capability.

A new and innovative approach to orbital operations planning was expected to effe

economies in the scale of DSN coverage required to support this critical phase of th

mission. For the purposes of operational simplicity, DSN coverage was classified in

two categories: “high activity,” when science opportunities would be most intensive, su

43

The Cassini Era: 1996–1997
as targeted satellite flybys and Saturn periapses; and “low activity,” when fewer scien

opportunities would permit lower data return volume. The science community had agre

that a data volume return of 4.0 gigabits per day for high activity periods and 1.0 gig

bit per day for low activity periods would be adequate to accomplish their science objective

Because Saturn would be above the plane of the ecliptic during the period of orbit

operations (2004–08), the daily view periods for the DSN antennas in the southe

hemisphere would be of shorter duration, and the received downlink signal-to-noise rat

about 1.5 dB less, than they would be for the DSN antennas in the Northern Hemispher

For this reason, the DSN agreed to provide coverage, most of the time, for antennas 

the Northern Hemisphere, Goldstone, and Madrid. High-activity data return would 

accommodated by the 70-m antennas and 70-m/34-m arrayed antennas in the Northe

Hemisphere. Low-activity periods would be covered by the 34-m Northern Hemisphe

antennas or the 70-m and 34-m Southern Hemisphere antennas, if necessary. 

The sustainable data rates on the X-band downlink during Saturn orbital operations al

depended on the position of Earth in its orbit around the Sun and on the change 

elevation of the spacecraft as it made its daily pass over the tracking station. When 

these variables were considered, it was estimated that the downlink data rates would va

over the range 14 to 166 kilobits per second.

In a joint effort to reduce the complexity and cost of daily orbital operations, the fa

tors just described were used by the DSN and Cassini mission planners to develop 

data return strategy based on an average pass length of about 9 hours. This strate

optimized the downlink capability with the defined science activity period while lim

ing the data rate changes on the telemetry downlink to two or three per station pa

Once developed, each strategy would remain in effect for a fixed period, such as 9

days, during which time data rates and pass lengths would not be changed. This arrang

ment promised significant economies in mission planning and operations effort for bo

DSN and the Cassini projects.

After the White House gave approval to proceed, Cassini was launched without incide

from Cape Canaveral, Florida, on 15 October 1997. White House approval to laun

was required by presidential directive due to the use of RTG units to power the Cassi

spacecraft. This matter had been the subject of a number of environmental protest demo

strations at Cape Canaveral in the weeks immediately preceding launch.

The Titan IV/B and Centaur Launch Vehicle functioned perfectly. “Right on the money

observed Cassini program manager Richard J. Spehalski. The sequence of post-launch even

including initial acquisition of the downlink by Canberra stations DSS 46 and DSS 45, w

432

Uplink-Downlink: A History of the Deep Space Networ
executed precisely as planned. First reports from the Cassini mission controllers indicated th

the angular deviation of the trajectory from its design value was insignificant at better th

0.004 degrees. Mission plans had called for an expected adjustment in the post-launch tr

jectory of 26 meters per second, but flight data derived from the DSN radio metric data 

the first few hours of two-way tracking showed that a correction of only one or two mete

per second would be necessary to correct for the small injection error. Early DSN telemet

from CDSCC also showed that all subsystems on the spacecraft, including the solid-sta

recorder, were operating normally. “I can’t recall a launch as perfect as this one,” said Cassi

mission director Chris Jones; “everything we see is within predictions, with no failures.”

With the spacecraft high-gain antenna pointed toward the Sun and the X-band uplink an

downlink established through the low-gain antennas, the DSN began the first 30 days 

continuous tracking on the 34-m antenna subnet at the rate of 21 passes per week. Durin

this time, mission controllers took advantage of the high data rate (14.2 kbps) available o

the downlink, due to the short spacecraft-to-Earth range and the relatively quiescent (no sc

ence) state of the spacecraft, to carry out a series of engineering and science instrume

maintenance activities. These activities included a checkout of the Huygens Probe about o

week after launch. Because of the near-perfect post-launch injection conditions, the first tr

jectory correction maneuver on 9 November required only a 2.7-meters-per-second adjustme

in spacecraft velocity to fine-tune its flight path. Real-time telemetry at 948 bps from DS

54 allowed the spacecraft controllers to observe the 34.6-second main-engine burn in progre

and provided reassuring evidence that this critical subsystem was functioning correctly.

By early January 1998, the Cassini flight team had completed all spacecraft activities plann

for the early phase of the mission. Onboard software, stored in the command and da

subsystem, had been directing spacecraft activities as planned, and the spacecraft thruste

were maintaining the spacecraft in its correct attitude in space. For the next 14 month

Cassini would fly with the HGA facing the Sun to shield the spacecraft from the inten

solar radiation characteristic of the inner solar system. Throughout this period, the uplin

and downlinks with the DSN would be maintained through either of the two low-ga

antennas, depending on the relative geometry of Earth, the Sun, and the spacecraft. Downlin

data rates and weekly DSN tracking schedules were adjusted to meet the predefined, returne

data volume requirements. With all its subsystems working perfectly, and period

instrument maintenance and spacecraft housekeeping activities dominating its routine sche

ule, Cassini moved steadily around its orbit toward an appointment with Venus on 2

April 1998, the first milestone on its seven-year voyage to Saturn.8

43

The Cassini Era: 1996–1997
EARTH-ORBITING MISSIONS

General

By 1997, almost two-thirds of the missions that composed the total DSN mission s

were missions of the Earth-orbital type. These are listed in the mission set for the Cassi

Era, shown in Figure 6-1. Together with the Deep Space missions, these accounted f

a Network operations load of 30 to 35 mission events being handled by the NOCC 

a typical 24-hour period in 1997. In addition to the real-time mission events, a typic

operations day for the NOCC would include two to five data playback sessions wi

the complexes. 

Some of these spacecraft, like the Solar Heliospheric Observatory (Soho), Polar, Win

and Geotail, were part of the continuing International Solar and Terrestrial Physi

(ISTP) program and had been supported by the DSN for several years. Others, li

Hotbird, were supported by the DSN only for the launch and early orbit period, 

few days at most. Some were technology satellites; others were communications sate

lites; and some were solely for scientific purposes. Except for the cooperative Spa

VLBI mission HALCA and the reimbursable ESA mission Hotbird, all were NAS

missions. However, the cooperative and reimbursable options for DSN support 

future, non-NASA missions remained open. There were a number of other NAS

missions, not listed in this set, for which the DSN assumed responsibility for pr

viding tracking support in the event of a spacecraft emergency. Appropriate authoriti

and procedures to invoke support of this kind were permanently in place in th

NOCC.

Spacecraft in low-Earth orbit (apogee less than 12,000 km) were supported on th

26-m or 34-m antennas, depending on their requirements for downlink data rece

tion and handling. Those in high-Earth orbit usually required 34-m HEF or 34-

BWG antennas.

The HALCA spacecraft was a special case that warrants further discussion because 

the new technology associated with its entry into the DSN. It was developed for th

Japanese VLBI Space Observatory Program (VSOP) and was known by that name pri

to its actual launch. Following a successful launch in February 1997, it became HALC

and participated in an international cooperative Space VLBI program for which the DS

provided some of the Earth-based antenna support.

434

Uplink-Downlink: A History of the Deep Space Networ
Space VLBI Observatory Program

The Space Very Long Baseline Interferometry (SVLBI) program was a two-mission, coo

erative venture among NASA, Japan’s Institute of Space and Astronautical Sciences (ISAS

and the Russian Astro Space Center (ASC). NASA participated in both missions wi

funding for the DSN; the National Radio Astronomy Observatory (NRAO) Very Lon

Baseline Array at Socorro, New Mexico; and the NRAO tracking station at Green Ban

West Virginia. 

As early as 1983, Gerry S. Levy and his JPL associates had shown that the resolutio

of an array of Earth-based VLBI antennas could be greatly increased by means of a sp

cial spacecraft which would act as an extension of the Earth-based “radio baseline.”9 Th

SVLBI program applied and extended these basic ideas to improve the resolution 

radio-astronomy images of celestial radio sources by extending the use of VLBI tec

nology into space. The SVLBI missions therefore had a space component and a groun

component, both of which heavily involved the DSN.

DSN involvement in the space component of the SVLBI project included the impl

mentation of a new subnetwork of 11-meter antennas with Ku-band uplink and downlin

capability. This effort is described later in this chapter. DSN participation in the groun

component of SVLBI as a co-observer with the DSN 70-meter antennas is discussed 

the Radio Astronomy section of this book.

The space component of the SVLBI program was to consist of two spacecraft: the VSO

(VLBI Space Observatory Program), provided by ISAS and launched in 1997, and th

RadioAstron, provided by ASC and due to be launched several years later. Each spac

craft would carry a radio-telescope antenna and suitable receiving equipment for makin

radio-astronomy observations from a high-Earth orbit. The DSN’s 11-meter antenn

would provide continuous tracking support to supplement the limited tracking resourc

of the other participants in the program. 

The VSOP antenna was capable of receiving signals in the three standard radio astro

omy bands, L-band (1.6 GHz), C-band (5.0 GHz), and Ku-band (22 GHz). The digitiz

radio astronomy data, together with time synchronization signals, was to be transm

ted to Earth over a Ku-band downlink at 128 Mbps. A Ku-band uplink carried tim

and frequency reference signals derived from a Hydrogen-maser at the Earth-based recei

ing stations to the spacecraft for use as a frequency reference. Spacecraft command an

control functions and generation of radio metric tracking data used an S-band uplin

and downlink that was completely independent of the Ku-band link. These functio

43

The Cassini Era: 1996–1997
were exercised from the Kagoshima Control Center and were not part of the DS

responsibility.

The VSOP spacecraft was successfully launched on 12 February 1997, on the then-ne

ISAS Mark-V launch vehicle, from the Kagoshima Space Center in Japan.10 The sate

lite was renamed HALCA after launch. Following initial acquisition of the S-band downlin

by the 26-m station at Goldstone, the Ku-band uplinks and downlinks were activat

and communications were established with the 11-meter subnet consisting of DSS 2

(Goldstone), DSS 33 (Canberra), and DSS 53 (Madrid). Three perigee-raise maneuve

done from 15 to 21 February, were used to place HALCA in a high elliptical orbit wi

an apogee of 21,400 km, perigee of 560 km, and orbit period of 6.3 hours. This hig

elliptical orbit had in inclination of 31 degrees (the latitude of the Kagoshima Spa

Center) and would enable VLBI observations on baselines up to three times longer tha

those achievable with Earth-based antennas. First interference fringes between HALC

and ground telescopes were found at the Mitaka, Japan, correlator in May, and at th

Penticton, Canada, and Socorro, New Mexico, correlators in June 1997. 

Tracking station passes varied in length from 10 minutes to as much as 5 hours, depen

ing on the position of the spacecraft in its orbit at the time of the station pass. Th

short-period orbit provided two or three passes per day at each complex. The DSN w

not required to perform any processing of the downlink data. It was simply record

on special wide-band VLBI-compatible tapes and shipped to designated locations in th

United States, Japan, and Canada. Special wide-band correlators at these centers process

the spacecraft observations together with corresponding data from the ground observ

tories, including the DSN 70-meter antennas, to produce the desired images of celest

radio sources.

436

Uplink-Downlink: A History of the Deep Space Networ
THE NETWORK

Complexes and Antennas

By 1997, when the Cassini Era became a reality in the DSN, the total number of ante

nas operated by the DSN around the globe had increased to twenty-four, twelve 

Goldstone and six at each of the Madrid and Canberra Complexes. The DSN al

engaged in spacecraft mission operations with many other institutions around the worl

each of which had one or more antennas of its own. 

The sites of the DSN antennas and Signal Processing Centers were identified accordin

to their geographical location, as shown in Figure 6-9. The sites of related antennas su

as Weilheim, Germany; Usuda, Japan; and Parkes, Australia, were identified in the sam

manner.

It was convenient to describe the Network in terms of several subnets according to the me

ric diameter of the antennas composing it. There were a 70-meter subnet, two 34-m subne

a 26-m subnet, an 11-m subnet, and several unique antennas such as DSS 13 and DS

17 at Goldstone. An inventory of antennas in the DSN in 1997 is given in Figures 6-1

6-11, and 6-12 for the Goldstone, Canberra, and Madrid complexes, respectively.

These tables show the various uplinks and downlinks that were available in 1997 

support space operations on each of the antennas. Comprehensive though this listin

was, substantial additions were planned for it in the immediate future. 

43

The Cassini Era: 1996–1997

Figure 6-9. Location identifiers for DSN and related sites.

Location Identifier for DSN and Related Sites

Number Range Geographic Description and Position*

00–29 JPL/Goldstone and the VLA, Socorro, NM

30–49 Pacific Basin: Between L = 180 and L = 270

50–69 European Basin: Between L = 345 and L = 90

70–89 Atlantic Basin: Between L = 270 and L = 345

90–99 Miscellaneous

100–999 GPS and Future Use

*Note: L = Longitude in degrees, measured east from zero longitude. 
438

Uplink-Downlink: A History of the Deep Space Networ

Figure 6-10. Goldstone Deep Space Communications Complex, 1997.

Goldstone Deep Space Communications Complex, 1997

DSS Diam., Type Uplinks Downlinks Operational

12 34 m, STD none none Decom’d. 2/96

13 34 m, BWG, R&D S, X, Ka S, X, Ka, Ku 6/90

14 70 m S S, X 64 m/70 m, 5/88

15 34 m, HEF X S, X 8/84

16 26 m S S 1/67

23 11 m, OVLBI X X, Ku 2/96

24 34 m, BWG X, S S, X 2/95

25 34 m, BWG S, X S, X, Ka 8/96

26 34 m, BWG X X 8/96

27 34 m, BWG, HS S S 7/95

28 34 m, BWG, HS S S 10/00

Figure 6-11. Canberra Deep Space Communications Complex, 1997.

Canberra Deep Space Communications Complex: 1997

DSS Diam., Type Uplinks Downlinks Operational

33 11 m, OVLBI X, Ku X, Ku 6/96

34 34 m, BWG X S, X 11/96

42 34 m, STD S S, X Decom’d. 12/99

43 70 m S S, X 9/87

45 34 m, HEF X S, X 12/84

46 26 m S S 12/83
The 70-m subnet would be provided with X-band uplinks for first use with Cassin

beginning with DSS 14 in 2000. Already, plans were being made to install an X-/K

band dichroic plate on the DSS 25 BWG antenna. This would be the first step 

providing an operational Ka-band downlink for use on the Deep Space-1 mission an

for project use with Cassini in 2000. The DSS 26 BWG antenna was being modifi

to demonstrate the more stringent antenna pointing capability required for Ka-ban

operation. 

Driven by the need to reduce maintenance and operations costs, the closure of th

26-m subnet by the end of Fiscal Year 2001 had been under consideration since 199

Several alternatives, including the automation of routine telemetry, command, an

monitoring functions, the transfer of low-Earth-orbiting spacecraft to NASA’s Wallo

Island facility, and eventually to a commercial ground network, were being active

pursued in 1997.

Ways of making more effective use of DSN antenna time were demonstrated in seve

al areas in 1996 and 1997. The “Multiple Spacecraft Per Antenna” concept w

demonstrated effectively at Goldstone in September 1997 with the successful trackin

of Mars Global Surveyor and Mars Pathfinder from a single antenna. Both spacecraft we

at Mars and both lay within the beamwidth of a single 34-m BWG antenna (0.06

degrees at X-band). Several hundred commands were transmitted to each spacecraft, an

good telemetry and two-way Doppler was obtained from each spacecraft. The oper

tional advantages of this mode of operation were clearly demonstrated, particularly tho

43

The Cassini Era: 1996–1997

Figure 6-12. Madrid Deep Space Communications Complex, 1997.

Madrid Deep Space Communications Complex, 1997

DSS Diam., Type Uplinks Downlinks Operational

53 11 m, OVLBI X, Ku X, Ku 6/96

54 34 m, BWG X S, X 10/97

61 34 m, STD S S, X Decom’d. 12/99

63 70 m S S/X 64 m/70 m, 7/87

65 34 m, HEF X S/X 4/87

66 26 m S S 12/84
related to switching the uplink from one frequency to another, and subsequent acqu

sition of individual spacecraft receivers. The DSN planned to develop this technique f

future use as the Mars Exploration initiative would provide more opportunities for effec

ing economy in usage of DSN antennas.

For many years, it had been the practice to make regular, biweekly Earth motion an

clock synchronization measurements between complexes by using two 70-m antenn

simultaneously to observe a celestial radio source. Comparison of time off-sets in th

observables provided a measure of the differences in time and frequency between th

complexes. In 1997, with the addition of updated VLBI equipment and precision da

from GPS receivers at the complexes, it became possible to accomplish the same biwee

ly measurements with two 34-m HEF antennas rather than two 70-m antennas. 

In November 1997, the Future Programs Council at JPL heard a briefing on the futu

of deep space communications. The scope of the briefing included optical as well 

conventional radio communications, but in the context of existing DSN antennas, 

recommended that “to meet the increased needs of a growing mission set, NASA shou

rapidly deploy Ka-band capability throughout the existing DSN as a low[-]cost pa

which would allow future missions to double their data return while cutting their (ante

na) contact time in half.”

In time, by 1997, that statement seemed to indicate the direction of future develo

ment for antennas in the Network. 

Ka-band Downlink

Along with design concepts for beam waveguide antennas, the advantages of Ka-ban

communication links and the application of these ideas to future uplinks and downlin

for the DSN were discussed by Joel G. Smith, Robert C. Clauss, and James W. Laylan

in three companion reports in 1987.11 These studies showed that a spacecraft-to-Ear

downlink on Ka-band (32 GHz) could carry telemetry data at 3 to 10 times the da

rate possible with an X-band downlink, given the same spacecraft transmitter weigh

antenna size, and power requirements. This enhancement in downlink performance deriv

from increased antenna gain at higher frequencies (shorter wavelengths), but was reduc

somewhat by other factors such as atmospheric and antenna losses and susceptibility 

wet or foggy weather. A more indepth study of the tradeoffs associated with Ka-ban

operation in the DSN was carried out in 1988. This study described a scenario for esta

lishing Ka-band as the primary Deep Space communications frequency of the futu

and proposed a baseline plan for reaching that goal.12 

440

Uplink-Downlink: A History of the Deep Space Networ
As the first two steps toward realization of Ka-band communication links in the futu

DSN, it was proposed that a Ka-band receiving capability should be added to the ne

research and development beam-waveguide antenna being built at DSS 13, and that 

Ka-band beacon experiment (KABLE) should be planned for the Mars Observer spac

craft due to be launched to Mars in September 1992.13

This methodology had been used to introduce the X-band into the Network in 197

as an S-/X-band experiment on the Mariner 10 missions to Venus and Mercury. Th

Ka-band transponder for the Mars Observer spacecraft was the first step in a paral

development plan for spacecraft device and component technology proposed by Arth

L. Riley.14

The BWG antenna at DSS 13 was completed by mid-1990, as described in the pr

ceding chapter, and its Ka-band capability was evaluated over the period July 199

through January 1991.15 The microwave feed package used on this antenna for KABL

consisted of an X/Ka-band dichroic plate and two low-noise amplifiers (LNAs), one f

X-band and one for Ka-band. While the X-band LNA used a simple high-electron mob

ity transistor (HEMT) to achieve a system temperature of 37 kelvin, the ultra-LNA f

Ka-band required the development of JPL’s first Ka-band cavity maser to achieve a sy

tem temperature of 5 kelvin.16 The Ka-band and X-band downlink signals, amplified b

the LNAs, were converted to intermediate frequency and delivered to separate digit

Advanced Receivers (ARX) for tracking, demodulation, and delivery to the telemet

decoders. A data-handling terminal carried out the telemetry recording and delivery task

Of the two advanced receivers, one was the unit that was being developed for the Galil

application in the DGT; the other was specially built for use at DSS 13 and wou

remain at the station. A special Doppler tuner was required for this unit to handle th

Doppler jerk (rate of acceleration) expected on the Ka-band downlink when MGS wou

be in orbit around Mars.

The Mars Observer spacecraft was equipped with a special 33-milliwatt Ka-band tran

mitter and used the concave surface of the subreflector on the spacecraft’s high-ga

antenna as an antenna for the Ka-band downlink. To keep the Ka-band downlink cohe

ent with the X-band uplink and downlink, its frequency, 33.66 GHz, was obtained b

simply multiplying the X-band downlink frequency (8.4150 GHz) by four. Telemet

and ranging modulation were provided on both downlinks. At this time, fiber-opt

cables were being introduced for intra-site communications and transmission of high

stable reference and timing signals between antennas on each complex. Full advanta

was taken of this new facility to connect DSS 13 to the SPC 10 Control Room som

20 miles away, where the existing ranging and Doppler equipment was located.

44

The Cassini Era: 1996–1997
The major objectives for KABLE included a telemetry demonstration, a ranging demo

stration, and a tracking experiment. The telemetry demonstration would prove the feasibili

of a telemetry link at Ka-band by collecting a minimum of one million bits of data, 

250 bits per second, with minimal errors. The ranging demonstration would follow th

telemetry demonstration and illustrate the correct demodulation of DSN ranging cod

at Ka-band. The tracking experiment would develop a database of Ka-band downlin

statistics including weather, system noise, temperature, and antenna performance for u

in the future development of Ka-band capability in the Network. 

By an unfortunate coincidence, the telemetry demonstration took place during some 

the worst weather conditions ever experienced in the Goldstone area. Heavy rains an

dense fog were daily occurrences. This type of weather has a major degradation effe

on Ka-band link performance and proved to be a limiting factor in reaching the da

collection goal for telemetry. Although the ranging demonstration was limited to tw

passes only, due to various equipment problems and to the weather, it yielded a suf

cient number of good ranging points for favorable comparison with theoretic

performance. Equipment problems and bad weather also limited the amount of trac

ing data that was gathered. Nevertheless, sufficient Ka-band tracking data was retriev

to show a potential improvement of 4 to 7 dB over X-band performance under equi

alent conditions.

Ironically, on 21 August 1993, just when the weather was improving and the equi

ment problems were being resolved, uplink and downlink communications with th

Mars Observer spacecraft were lost. Later investigations led to the conclusion that th

spacecraft had been destroyed during the engine pressurization sequence prior to th

maneuver for Mars orbit insertion. 

Despite its abrupt ending, sufficient data was obtained to declare the KABLE effort pa

tially successful. The data that had been collected was thoroughly analyzed, and it ultimate

provided a strong justification for a repeat experiment as soon as another opportuni

presented itself.17

That opportunity would not be long in coming. In November 1996, when the Ma

Global Surveyor spacecraft was launched on a mission similar to that of the ill-fated Ma

Observer, it carried with it a much-improved version of the original Ka-band technol

gy experiment called KABLE-II. Although KABLE-II was identical in concept to th

earlier experiment, it benefited from several changes to the spacecraft and ground el

ments of the link. The Ka-band transmitter power had been increased to approximate

1 watt, and a change had been made to the way in which the frequency of the dow

442

Uplink-Downlink: A History of the Deep Space Networ
link Ka-band signal was derived in the spacecraft transponder. This change effective

placed the downlink signal frequency in the center of the receiving pass-band, rath

than to one side of it, as was the case in Kable-I. Since the microwave components 

the DSS 13 BWG antenna, particularly the dichroic plate, were optimized to receive 

this band-center frequency, substantial loss in the downlink signal margin was avoide

At DSS 13, a new seven-element Ka-band array feed was used to receive the downlin

and point the 34-m antenna with millidegree precision; Block V receivers replaced th

earlier ARX developmental versions; and numerous other improvements related to ope

ational reliability were made. 

When the MGS spacecraft was pointed to Earth in mid-January 1997, strong signa

were immediately received at DSS 13 and simultaneous X-/Ka-band tracking was ca

ried out on six occasions thereafter. The array feed tracked the spacecraft within 1 millidegr

in angle, and both carriers were tracked simultaneously to generate Doppler data by a

experimental tone-tracker. Measurements were in good agreement with theory. The telem

try experiment began in February with an improved low-noise tracking feed which n

only incorporated a multimode coupler to generate pointing error signals for driving th

antenna pointing system, but also was cooled to reduce the system noise temperature

On 21 March, the KABLE-II experimenters reported that a major objective had bee

successfully accomplished. Telemetry data received over the 1 watt, Ka-band link at 

kbps had been compared bit-by-bit with data received over the 25-watt X-band dow

link. All 12 million contiguous bits were in agreement. There were no errors. This eve

marked the first error-free telemetry reception at Ka-band in the DSN. 

At this time, the Ka-band array feed, which had been replaced by the multimode-co

pler feed at DSS 13, was installed and tested on the DSS 14 antenna in preparatio

for the start of Ka-band efficiency tests of the 70-m antenna in May. This capabili

would be needed for Cassini in the years ahead.

In mid-April, real-time telemetry data received from MGS over the Ka-band and th

X-band links was presented to the MGS project operations team at JPL for evaluatio

Dual-frequency tracking and ranging measurements were also made at this time. Th

experimental Ka-band downlink was received at DSS 13, while an operational X-ban

uplink and downlink was maintained at DSS 15. Both downlinks had been convert

to 300-MHz IF frequency and transferred over fiber-optic circuits to SPC 10 for telem

try and radio-metric data processing and transmission to JPL.

44

The Cassini Era: 1996–1997
The KABLE-II telemetry demonstrations with MGS at DSS 13 continued as schedul

through 8 May 1997. The successful demonstrations of Ka-band technology occasion

by the two KABLE experiments lent impetus to its transfer to the operational Netwo

beginning with DSS 14 and DSS 25 at Goldstone.

The first two missions that would be carrying Ka-band downlinks to demonstrate a

operational rather than an experimental capability in the DSN were the New Millenniu

mission DS-1 and the Cassini mission to Saturn.

DS-1 was a technology demonstration mission with secondary scientific objective

Primary communications would be conducted on X-band, and DSS 25 was to pr

vide a Ka-band receive capability as an operational technology demonstration. DS

13 would also provide some analytical support. DS-1 would not be launched befo

the middle of 1998.

Cassini also planned to use X-band for its primary telemetry and radio metric suppo

but, additionally, it planned an extensive project program that would be accomplish

using a combination of S-, X-, and Ka-band downlinks and X-band and Ka-band uplink

The Ka-band uplink and downlink were required to support the Cassini Gravitation

Wave Experiment in 2001.

While the DSN telecommunications engineers had been pursuing a path leading to a

operational Ka-band capability in the Network, spacecraft telecommunications enginee

had been pursuing a somewhat parallel path in developing an X-band/Ka-band transpo

der for future spacecraft. The NASA Deep Space Transponder (DST) had been 

development since 1991 and was intended for first use with Cassini, at that time plann

for launch in 1996. It would replace the existing S-band transponders, which, with a

external S-band-to-X-band down-converter to provide the X-band capability, had bee

used on all previous planetary spacecraft. Using conventional spacecraft technology, th

DST contained an automatic phase-tracking receiver for X-band uplink only and an X

band exciter to drive redundant downlink X-band transmitters. It provided appropria

reference frequency signals to devices external to the DST for the generation of ind

pendent Ka-band and S-band downlink signals.

The Cassini spacecraft was launched in October 1997, carrying the DST into space f

the first time. Cassini would depend on the DST for its primary spacecraft commun

cations links with the DSN; uplink and downlink on X-band for telemetry, comman

and radio metric data; and downlink only on Ka-band and S-band for project and gra

ity-wave experiments. 

444

Uplink-Downlink: A History of the Deep Space Networ
The Ka-band transponder, also known as the Small Deep Space Transponder, had bee

under development since 1995 and was designed specifically for Ka-band uplink an

downlink operation.18 It included a selectable X-band capability that could be switch

in or out as required, as well as several state-of-the-art components, including samplin

mixers, a Ka-band dielectric resonator oscillator, and microwave monolithic integrat

circuits (MMICs) to perform the functions of up and down frequency conversion, mo

ulation, and amplification. It was proposed for first use as a telecommunications evaluatio

experiment on DS-1, to be launched in 1998.

Ka-band was definitely on the move in the DSN in 1997, but its arrival as an oper

tional capability lay several years in the future.

Orbiting VLBI Subnetwork

As discussed earlier in this chapter, Space Very Long Baseline Interferometry (SVLB

was a cooperative project among NASA, ISAS, and ASC, representing space agenci

from the United States, Japan, and Russia. ISAS provided the VSOP (HALCA) spac

craft, ASC was to provide the RadioAstron spacecraft, and the Russian tracking statio

and NASA provided the SVLBI subnet of four tracking stations. One of these statio

was the existing 14-meter NRAO Green Bank station in West Virginia. The other thr

antennas were built by NASA specially for this cooperative project and, at their com

pletion in 1996, became part of the Deep Space Network. One antenna, with its uniq

electronics, was installed at each complex. Within the DSN, they were referred to co

lectively as the Orbiting VLBI (OVLBI) 11-meter subnet and designated DSS 23, DS

33, and DSS 53 for Goldstone, Canberra, and Madrid, respectively. However, from th

overall project viewpoint, they remained part of the SVLBI subnet.

The main functions of 11-meter stations were to automatically acquire and track th

spacecraft X-band and Ku-band downlinks, generate and provide two-way integrat

Doppler data to the DSN Navigation Subsystem; provide uplink to the spacecraft wi

a phase-stable reference frequency tied to the DSN Hydrogen Maser Frequency sta

dard at each site; and receive, demodulate, and record the 144 Mbps downlink telemet

data in special VLBA and/or S-2 data format. The spacecraft data would be deliver

to the project for later correlation with data from the co-observing ground telescope

These functions were to be performed autonomously, without the need for operat

intervention except to change recording tapes, at a frequency of 4 passes per day, 7 da

per week. Interfaces with the existing DSN systems would provide the new antenn

with frequency and time references; monitor and control functions; and the necessa

44

The Cassini Era: 1996–1997
schedule, frequency prediction, and antenna pointing and orbital state vector inform

tion to enable autonomous operation.19

Initial studies in 1990 had shown that considerable cost savings to NASA would resu

from the use of commercially available resources, rather than JPL “in-house” resource

to provide the antennas. A comprehensive set of technical design requirements was pr

pared in 1991, and after due process, a contract for the design and implementation 

three high-precision 11-meter antennas and associated electronics and software as a “tur

key” package was awarded to Scientific-Atlanta (S-A) Corporation in September 199

JPL was responsible for selecting and preparing the sites and providing access road

antenna foundation, buried cable conduits, air-conditioned buildings, power, water, an

related facilities. 

Although the design was based on an S-A standard, the 11-meter production antenn

a great deal of new development was necessary to meet the extremely tight design requir

ments for frequency and phase stability required for the intended OVLBI application

The functional block diagram in Figure 6-13 shows the interfaces between the 11-

antenna in the OVLBI subnet and various systems of the Network.

Each station in the new subnetwork contained two new subsystems: the OVLBI Trackin

Subsystem (OTS) and the OVLBI Data Subsystem (DTS).

The OVLBI Tracking Subsystem included the 11-meter-diameter antenna, on a

azimuth/elevation mount, with a third “tilt” axis to allow for a direct overhead pass wit

out loss of tracking data due to the keyhole effect inherent in AZ/EL mounts. Concentr

five-horn monopulse feeds in a cassegrain subreflector configuration handled uplink an

downlink signals at X-band, while the center horn also acted as a common receivin

aperture for Ku-band. The Ku-band monopulse error signals were derived from a TE2

mode coupler at the base of the horn. Low-noise amplifiers, microwave componen

tracking receivers, antenna-control servos and data receivers and demodulators provid

for antenna pointing and downlink data reception and demodulation. Frequency co

verters and local oscillators driven from computers in the Data Tracking Subsyste

provided the important Doppler compensation and signal coherence functions. The uplin

for RadioAstron was provided by a small 5-watt solid-state X-band transmitter, wh

the uplink for VSOP was provided by a 0.5-watt Ku-band transmitter. 

446

Uplink-Downlink: A History of the Deep Space Networ
On these antennas, special measures were taken to minimize the effect of temperatu

variations on the phase stability of the X-band and Ku-band signals. Transmission 

these signals between the antenna and the Control Room was carried on fiber-opt

cables, and all frequency conversion equipment was located in the temperature-regula

ed Control Room. The temperature of microwave and optical equipment mounted o

the antenna itself was maintained to within ±1.0 degrees of normal by an independen

44

The Cassini Era: 1996–1997

Figure 6-13. OVLBI Subnetwork functional block diagram. The following abbreviations are us

in this diagram:

FTS Frequency and Timing System

DMC DSN Monitor and Control

NOCC Network Operations Control Center

NMC NOCC Monitor and Control

NSS NOCC Support Subsystem

NAV NOCC Navigation

DSS Deep Space Station

SPC Signal Processing Center

GCF Ground Communications Facility

PROJ Flight Project Mission Operations Teams

S/S Subsystem

DSS

FTS

M&C

RF/NF

MONITOR

REF. FREQ.,

TIME

TELEMETRY, TRACKING DATA

DOPPLER DATA

DOPPLER

DATA

DOPPLER DATA

STATE VECTORS

STATE VECTORS

PROJECT

TACTICAL

INTERCOM

OVLBI

DATA

S/S

FACILITIES

GCF

DMC NSS

NAV

NMC

SPC GCF NOCC PROJ

OVLBI

TRACKING

S/S

SCHEDULE

MONITOR

SCHEDULE,

STATE VECTORS,

FREQ. PREDICTS SCHEDULE, STATE VECTORS,

FREQ. PREDICTS
proportional air-conditioning system. To further enhance phase stability, the fiber-opt

cables between the antenna and the Control Room were buried six feet below groun

level. Except for routine maintenance and changing of recording tapes, the station w

fully operated by a ground station control computer as part of the OTS. 

The OVLBI data subsystem contained various components that were peculiar to th

VSOP and RadioAstron missions. A Doppler compensation computer drove the loc

oscillators in the Tracking Subsystem, which programmed out the expected Doppler fr

quency shift on both the uplink and downlink. A Doppler extractor integrated th

Doppler frequency shift and provided this data to the DSN Navigation Subsystem f

calculating the precise spacecraft position. After decoding, the telemetry data containin

the VLBI observations from the spacecraft were recorded digitally in a special Very Lon

Baseline Array (VLBA) format. An additional interface to provide the VLBI data to th

Canadian S-2 recording subsystem was added later.

In August 1995, four years after the award of the contract, factory acceptance testin

of the first two systems for Goldstone and Canberra was successfully completed at Scientifi

Atlanta. The hardware performed well, and performance against critical requiremen

relating to antenna gain-to-system noise temperature (G/T), phase stability, Doppl

compensation, tracking accuracy, and telemetry bit error rate was well within specific

tion. There were, however, a significant number of software anomalies which would 

corrected over the following weeks. The Goldstone system was dismantled and prepar

for shipping, while the Canberra system was retained on the antenna test range to pr

vide a test-bed for clearing the software anomalies. The Canberra system was shipped 

few weeks later, but the system for Madrid was delayed by shipping and other pro

lems and did not reach the Madrid Complex until May 1996.

By then, the Goldstone system (DSS 23) was acquiring and tracking the SURFSA

spacecraft automatically without operator intervention at X-band, as well as generatin

two-way Doppler on a regular basis. The SURFSAT tracks were continued througho

the year to gain experience, while the Doppler data was evaluated for quality and acc

racy and the last of the software problems were worked on. 

A photograph of DSS 23 at the Goldstone Apollo Site with the DSS 24 BWG ante

na in the background is shown in Figure 6-14.

In May and June, while the Canberra system (DSS 33) was completing its onsite sy

tem acceptance testing, assembly of the antenna for DSS 53 began at the Madrid sit

By the end of 1996, all three 11-m antennas had been completed and most major pro

448

Uplink-Downlink: A History of the Deep Space Networ
lems with the DPRG and the Doppler and phase generation software had been solve

Full end-to-end capability between a ground station (DSS 33) and the VLBI correlat

at Socorro, New Mexico, was demonstrated for the first time in December, using X

band data from the SURFSAT spacecraft. At that time, none of the 11-m stations h

yet been exposed to a Ku-band downlink, and the VSOP launch, set for February 199

was then just over two months away.

In mid-January 1997, the SURFSAT spacecraft was commanded to switch its downlin

from X-band to Ku-band to give the new 11-m stations some experience in routin

tracking at the frequency they would be seeing for the VSOP downlink. For the ne

four weeks, all 11-m stations engaged in routine tracking of the SURFSAT Ku-ban

downlink, while final software deliveries were installed and preparations were made f

the start of VSOP inflight operations.

The VSOP launch took place on 12 February 1997, and the first Ku-band track 

HALCA, as it became known after launch, was made at DSS 23 on 20 March. Wi

minor exceptions, 11-m subnet support for HALCA operations in 1997 was satisfact

44

The Cassini Era: 1996–1997

Figure 6-14. DSS 23, 11-meter OVLBI antenna at Goldstone, 1996.
ry and is described earlier in this chapter. In the longer term flight operations enviro

ment, however, the 11-m subnet required significant operations and engineering effo

from JPL and the Complexes to meet most of its design specifications. 

Emergency Control Center

Each of the facilities that compose the DSN had a unique set of policies and proc

dures to cover emergencies and disasters that might occur in its own particular locali

The response of each facility to an emergency situation is determined by its own set 

standard emergency procedures. Should the capability of the overall Network be affec

ed by the local emergency or the steps taken to deal with it, the Network situatio

would be handled by the Operations Chief at the NOCC using whatever alterna

resources were at his disposal at the time. However, the loss of the NOCC at JPL, f

whatever reason, would critically impair the ability of the entire Network to contin

support for inflight spacecraft.

Aware of this situation, the Galileo project had, in 1995, already developed a capabi

ty to conduct the critical “insertion into Jupiter orbit” phase of its mission from Goldston

in the event that a natural disaster precluded operations at JPL. A key feature of th

fairly basic emergency center was the ability to send commands to the Galileo spacecra

from any DSN 70-m antenna, independent of support from the regular Galileo m

sion control center at JPL.

As a consequence of the growing perception of Network vulnerability to the occurren

of a disaster at JPL, NASA Headquarters soon requested that DSN develop and pu

lish an official Network Disaster Plan. The Network Disaster Plan recognized the potent

for disablement of the NOCC due to earthquake, bomb threat, fire, or industrial d

pute, and established appropriate procedures to be followed by Network personnel. Th

procedures involved the relocation of basic NOCC and mission control activities to a

alternate location at the Goldstone Deep Space Communications Complex (GDSCC

located about 120 air-miles northwest of JPL. There, in 1996, a permanent new fac

ity called the Emergency Control Center (ECC) was implemented, with voice and bas

data communication capabilities, specifically for the purpose of continuing Network an

mission control activities on a limited scale in the event of a disaster at JPL.21

In its original concept, the ECC was intended to accommodate only the DSN pe

sonnel involved with Network control. It quickly became evident, however, that th

spacecraft and mission control facilities that were accommodated in the same Spa

Flight Operations Facility (SFOF) building at JPL as the NOCC were equally vulne

450

Uplink-Downlink: A History of the Deep Space Networ
able to the effects of a disaster. Under the direction of the Telecommunications an

Mission Operations Directorate (TMOD), the design was broadened to include the

latter capabilities in addition to those required for Network control, and the facili

became the TMOD ECC. 

In its basic form, the TMOD ECC consisted of a central router which could be co

nected, on demand, to the Goldstone Signal Processing Center (SPC) via an ethern

link and to the SPCs at Canberra and Madrid via permanently available and dedicat

voice/data communication circuits. By design, the circuits to both of the overseas sit

bypassed the high-earthquake-risk Los Angeles area. In the event of an emergency, th

Complexes would be instructed to patch their communications circuits to alternate com

munications routers which would redirect their communications traffic to the ECC 

Goldstone rather than to the NOCC at JPL. 

Within the ECC, an ethernet LAN connected the central router to several Hewlet

Packard and Sun Microsystems high-capacity workstations arranged in a 10-base T-hu

configuration. Most of these were for the use of spacecraft and mission controllers 

carrying out navigation, command, telemetry data handling, and sequence generatio

functions. Network control functions and the generation and dissemination of predi

tion data products for the antenna pointing, radio metric, telemetry, and frequen

control subsystem were carried out at a large VAX workstation. A DSN data base w

kept current by frequent downloading of current data from the active Network suppo

subsystem in the NOCC. Likewise, flight project software for the spacecraft and m

sion workstations was updated on a regular basis to reflect all changes and revisions.

Funding for implementation of the ECC task was in place by mid-1996, and respo

sibilities for development, planning, and implementation were assigned. The ECC w

to be located at the Echo site at Goldstone in the vacant control room of the DSS 1

antenna, which had been decommissioned from DSN service earlier in 1996. Und

pressure to be ready prior to the Cassini launch in October 1997, progress was rapi

By early 1997, the workstations were installed in the ECC and testing had begun. La

deliveries of the remaining equipment and a “freeze” on all new implementation acti

ity in the Network during the Mars Pathfinder landing and Mars surface operations 

July delayed the completion of the work until mid-August, when Cassini and Ulyss

mission controllers were able to begin evaluation of the ECC for flight operations su

port. The first tests with Canberra and Madrid used 28-kilobits-per-second communicatio

circuits routed through JPL, since the special 512-kilobits-per-second direct circuits betwe

the ECC and the overseas sites had not yet been made available to JPL. 

45

The Cassini Era: 1996–1997
Meanwhile, the Cassini project had developed a new launch “constraint” requireme

for an independent back-up for the existing Cassini Launch Operations Center at JP

Fortunately, the 28-kilobits-per-second circuits could be used to satisfy the newly impos

the Cassini launch criteria in the event of further delay in the availability of the wid

band 512-kilobits-per-second circuits. A few weeks later, these circuits did become availab

just in time to fully test the system with the overseas sites and to satisfy the new Cassi

requirements. 

The TMOD Emergency Control Center was reported to be operational for all JPL flig

projects on 6 October 1997. Cassini was successfully launched nine days later, with th

ECC providing back-up for its prime Launch Operations Center at JPL. 

The ECC was first used for full in-flight mission support by Galileo at the end 

October 1997. A complete track, including planning tasks and spacecraft comman

functions, was run successfully from the ECC by Galileo flight operations personn

Similar demonstrations were planned to familiarize Ulysses, Voyager, and Mars Glob

Surveyor operations personnel with the capabilities (and limitations) of the new fac

ity. In due course, these demonstrations came into regular scheduled use as a mea

of keeping the ECC in a state of readiness and exercising its potential users in eme

gency awareness. 

452

Uplink-Downlink: A History of the Deep Space Networ
OTHER ASPECTS

The years 1996–1997 brought to a close the traditional form of mission operations th

the DSN had employed to support all of NASA’s planetary missions, and many of 

lunar and Earth-orbiting missions, for almost forty years. New, more efficient, and le

costly ways of conducting mission operations, including a move to Ka-band frequencie

were being introduced in the Network to match NASA’s call for “faster, better, chea

er” missions. In the opening years of the Cassini Era, Mars Global Surveyor and Ma

Pathfinder, the first planetary missions designed to new guidelines, were launched on 

fast track to Mars. Cassini, the last planetary spacecraft based on the old principles, bega

its long mission to Saturn.

While the proper business of the DSN was always the support of NASA’s inflight spac

craft missions, “mission operations” represented only one aspect of DSN history ov

the period covered by this book. Technology, science, and organization, although n

directly involved with “mission operations”, were also essential to the growth, scientif

stature, and fiscal well-being of the Network during that time. 

To this point, the narrative has emphasized “mission operations” in terms of five maj

eras of planetary missions from 1957 though 1997. With that completed through th

Cassini Era, we turn now to consider other aspects of DSN history, beginning with th

growth of technology in the DSN. 

45

The Cassini Era: 1996–1997
Endnotes

1. Jet Propulsion Laboratory, Telecommunications and Mission Operatio

Directorate, “Bridging the Space Frontier” (30 January 1998). http://deepspace.jp

nasa.gov/920/public/922_strat_plan/.

2. Voyager Web site: http://www.jpl.nasa.gov/releases/98/vgr217.html.

3. NEAR Web site: http://near.jhuapl.edu/.

4. Mars Global Surveyor Web site: http://mars.jpl.nasa.gov/mgs/.

5. Mars Pathfinder Web sites: http://www.jpl.nasa.gov/marsnews, http://mpfwww.jp

nasa.gov/mpf/engineering.html.

6. N. R. Mysoor, J. D. Perret, and A. W. Kermode, “Design Concepts and Performan

of a NASA X-band (7162 MHZ/8415 MHz) Transponder for Deep-Spa

Spacecraft Applications,” TDA Progress Report PR 42-104, October-Decemb

1990 (15 February 1991), pp. 247–56.

7. N. R. Mysoor, J. P. Lane, S. Kayalar and A. W. Kermode, “Performance of a Ka-ban

Transponder Breadboard for Deep-Space Applications,” TDA Progress Report P

42-122, April-June 1995, (15 August 1995), pp. 175–83.

8. Cassini Web site: http://www.jpl.nasa.gov/cassini.

9. VSOP Web site: http://www.vsop.isas.ac.jp.

10. J. S. Ulvestad, C. D. Edwards, and R. P. Linfield, “Very Long Baselin

Interferometry Using a Radio Telescope in Earth Orbit,” TDA Progress Report P

42-88, October-December 1986 (15 February 1987), pp. 1–10.

11. J. G. Smith, “Ka-band (32-GHz) Downlink Capability for Deep Spa

Communications,” TDA Progress Report PR 42-88, October-December 1986 (1

February 1987), pp. 96–103; J. W. Layland and J. G. Smith, “A Growth Path f

Deep Space Communications,” TDA Progress Report PR 42-88, Octobe

December 1986 (15 February 1987), pp. 120–25; R. C. Clauss and J. G. Smit

“Beam Waveguides in the Deep Space Network,” TDA Progress Report PR 42-8

October-December 1986 (15 February 1987), pp. 174–82.

454

Uplink-Downlink: A History of the Deep Space Networ
12. J. W. Layland, “Ka-band Study-1988, Final Report,” 890-212, JPL Document D

6015, (Pasadena, California: Jet Propulsion Laboratory, 15 February 1989).

13. J. G. Smith, “Proposed Upgrade of the Deep Space Network Research an

Development Station,” TDA Progress Report PR 42-88, October-December 198

(15 February 1987), pp. 158–63; A. L. Riley, D. M. Hansen, A. Mileant, and R. W

Hartop, “A Ka-band (32 GHz) Beacon Link Experiment (KABLE) With Ma

Observer,” TDA Progress Report PR 42-88, October-December 1986 (15 Februa

1987), pp. 141–47. 

14. A. L. Riley, “Ka-band (32 GHz) Spacecraft Development Plan,” TDA Progre

Report PR 42-88, October-December 1986 (15 February 1987), pp. 164–73.

15. S. D. Slobin, T. Y. Otoshi, M. J. Britcliffe, L. S. Alvarez, S. R. Stewart, and M. M

Franco, “Efficiency Calibration of the DSS 13 34-m Diameter Beam Wavegui

Antenna at 8.45 and 32 GHZ,” TDA Progress Report PR 42-106, April-June 199

(15 August 1991), pp. 283–89.

16. J. Shell and R. B. Quinn, “A Dual-Cavity Ruby Maser for the Ka-band Lin

Experiment,” TDA Progress Report PR 42-116, October-December 1993 (1

February 1994), pp. 53–70.

17. T. A. Rebold, A. Kwok, G. E. Wood, and S. Butman, “The Mars Observer Ka-ban

Link Experiment,” TDA Progress Report PR 41-117, January-March 1994 (15 M

1994), pp. 250–82. 

18. N. R. Mysoor, J. P. Lane, S. Kayalar, and A. W. Kermode, “Performance of a K

band Transponder Breadboard for Deep-Space Applications,” TDA Progress Repo

PR 42-122, April-June 1995 (15 August 1995), pp. 175–83.

19. J. Ovnick, “DSN Orbiting VLBI Subnet, Task Implementation Plan,” JP

Document D-7787, 803-120, Vol. 1 (August 1990).

20. J. Ovnick, “DSN Orbiting VLBI Subnet, Design Requirements,” JPL Document D

9619, DM515606 (November 1993). 

21. Jet Propulsion Laboratory, “Deep Space Network Standard Operations Plan,” DS

Document 841, Vol. 1, DSN Operations (31 July 1996), p. 14-1.

45

The Cassini Era: 1996–1997
Chapter 

The Advance of Technology 

in the Deep Space Network

457
THE DSN TECHNOLOGY PROGRAM 

No history of the DSN would be complete without a full appreciation of its contrib

tion of advanced technology to the successful development of the Network. The wellsprin

of new and innovative ideas for increasing the existing capability of the Network; f

improving reliability, operability, or cost effectiveness; or for enabling recovery from pote

tial mission-threatening situations has resided, from the very beginning of the Network

history, in a strong program of advanced technology, research, and development. Know

by various names through the years, the numerous elements of the advanced technol

gy program were formally identified as a complete entity and placed under the directio

of the newly established Technology Office of the Telecommunications and Missio

Operations Directorate (TMOD) in 1997. It was known as the TMOD Technolo

Program. The program scope was further expanded to include technologies relevant 

the full end-to-end Deep Space Mission System (DSMS). This expansion included flig

components of the physical communications links (data services) and added missio

services activities like protocol developments, mission planning and execution tools, sc

ence data visualization, and the merging of tools and autonomy.

These disciplines covered almost every aspect of DSN-related technology. Theoretical wo

in any of them could always be complemented with experimental work in well-equipp

laboratories and machine shops at JPL and verified with field measurements at DSS 1

which was maintained primarily for research and development (R&D) purposes.

Prior to 1997, the program was known most generally as the DSN Advanced System

Program and covered antennas, low-noise amplifiers, Network signal processing, frequen

and timing, radio metric tracking, navigation, Network automation, atmospheric pro

agation. It also involved the evolution of the program research and development trackin

station, DSS 13, at Goldstone. These were all elements of ground-based systems. 

1985, a second Systems Development Program was added to cover telecommunicatio

systems analysis, spacecraft radio communication systems, and inflight demonstratio

of new uplink and downlink communications systems.

Due in no small part to the unremitting efforts of Nicholas A. Renzetti to ensure th

the results of these efforts were properly documented, a continuous record of the ear

work carried out under the DSN Technology Program was published by JPL in a seri

of progress reports. Starting in 1969 as Volume II of the JPL Space Programs Summa

37-XX series, it became the DSN Progress Reports in 1971, TDA-PRs in 1980, an

the TMO-PRs in 1998. In August 1994 the series began publication on the World Wi

458

Uplink-Downlink: A History of the Deep Space Networ
Web. An index of all articles published after 1970 also became available online at th

time. (See the appendix at the back of the book.) 

The technology underlying many of the major engineering changes, discussed earlier 

the context of DSN operations support for flight missions, was described by James W

Layland and Lawrence L. Rauch in 1997 (see section 1 of the appendix). As tho

authors made clear, most of the progress in antenna design; uplink and downlink pe

formance improvement; and the application of radio metric techniques to spacecra

navigation, radio science, radio astronomy, and radar astronomy originated in the DS

program of advanced research. These new technologies were later made available to th

DSN engineering groups for implementation into the operational Network.

This phase of DSN endeavor is illustrated by tracing the advancement of technology 

those key areas. The material that follows is derived from the work of Layland an

Rauch and is intended for the general reader. The technical reader is referred to th

appendix at the back of the book, which cites significant publications associated wi

each topic.

The Great Antennas of the DSN

A photograph of the NASA Deep Space Communications Complex near Canberr

Australia, is shown in Figure 7-1. The largest antennas in the photo are quasi-parabol

reflector antennas, one with a diameter of 70 meters; the others, 34 meters. These we

used for deep space mission support, while the other, smaller antennas, 26-meter 

9-meter antennas, provided tracking support for Earth-orbiting missions.

Each of the antennas has what is termed a Cassegrain configuration with a seconda

reflector mounted on the center axis just below the focal point of the primary reflect

“dish.” The secondary reflector serves to relocate the focal point closer to the surface 

the main dish and thus establish a more convenient location for the low-noise amp

fiers, receivers, and powerful transmitters.

The efficiency with which parabolic antennas collect radio signals from distant spacecra

is degraded to some extent by radio noise radiated by the Earth terrain surrounding th

antenna. This form of radio noise is known scientifically as “black body radiation” an

is a physical characteristic of all material with a temperature above absolute zero (-27

degrees Celsius or 0 kelvin). The magnitude of noise power radiated by a material bod

depends on its temperature. While it is incredibly small at the temperature of typic

Earth surfaces, it is enormous at the temperature of the Sun, for instance. All parabo

45

The Advance of Technology in the Deep Space Network
radio antennas have sidelobes in the beam pattern, and the magnitudes of those sid

lobes can increase as the antennas deviate from the ideal shape. The shape of the bea

and its sidelobes is essentially the same whether the antenna is used for transmitting 

receiving signals. The sidelobes are analogous to the circles of light surrounding the ma

beam of a flashlight when it is held close to a reflecting surface.

When an antenna is used for transmitting a strong signal to a spacecraft, the sidelobes a

of no great consequence. However, when the antenna is receiving a weak signal from a d

tant spacecraft, particularly at or near the horizon, the “Earth noise” picked up by t

sidelobes is sufficient to obscure the spacecraft signal in the extremely sensitive receivers us

on the DSN antennas. This interference produces errors in the data stream being deliver

to the spacecraft engineers and scientists, and it may cause the DSN receivers and ante

nas to lose the spacecraft signal altogether, in which case the data stream is completely lo

The earliest antennas in the DSN (Figure 7-2) were of commercial design and were pa

abolic in shape. Then, as now, the actual efficiency of the antenna represented a compromi

between maximum signal-gathering capability and minimum susceptibility to radio noi

picked up from the surrounding Earth.

460

Uplink-Downlink: A History of the Deep Space Networ

Figure 7-1. The Deep Space Communications Complex in Canberra, Australia
Improved technology that could reduce the sidelobes and increase the signal collectio

capability (gain) of future DSN antennas appeared in the Advanced Systems Progra

in the early 1970s. The new technology was based on a “dual-shape” design where

the surface shapes of both the primary and secondary reflectors were modified to ill

minate the slightly reshaped “quasi-parabolic” surface of the main reflector mo

uniformly. However, it was not until the 1980s, when the first 34-meter high-efficie

cy antennas were built, that the new “dual-shape” design saw operational service in th

Network (Figure 7-3). 

These antennas were needed by the DSN for support of the Voyager spacecraft in the

tour of the outer planets. At the time, the DSN was in transition from the lower, le

capable S-band (2.3 GHz) operating frequency, for which the early spacecraft and ante

nas were designed, to X-band (8.4 GHz), a higher, more capable operating frequenc

When X-band technology became available in the DSN, largely as a result of work 

the Advanced Systems Program, all the later spacecraft and DSN antennas were design

to operate at X-band frequencies. These antennas were therefore the first to be op

mized for performance at X-band.

46

The Advance of Technology in the Deep Space Network

Figure 7-2. An early parabolic design of a DSN antenna.
As the Voyager 2 spacecraft headed outward toward Neptune, it was recognized that a

increased signal-collecting area was needed on Earth to effectively support this uniq

science opportunity. The DSN’s largest antennas at the time were 64-m parabolas of th

original design. Calculations showed that the best investment of scarce construction fun

would be to modify these antennas, using the dual-shape design, to expand their diam

eter to 70 m. It was also apparent that the upgraded large antennas would benefit th

planned Galileo and Magellan missions.

Completed in time for support of Voyager 2 at Neptune, the 70-m enhancement pro

ect (Figure 7-4) resulted in an increase of more than 60 percent in the effective collectin

area of these large antennas. Fully half of the increase was attributed to the dual-shap

design, a product of the DSN Advanced Systems Program.

462

Uplink-Downlink: A History of the Deep Space Networ

Figure 7-3. The quasi-parabolic 34-m high-efficiency (HEF) antenna, DSS 15.
46

The Advance of Technology in the Deep Space Network

Figure 7-4. A 70-meter antenna with dual-shape reflector design.
By the end of the century, several new 34-m antennas employing the dual-shaped refle

tor design in conjunction with beam waveguide (BWG) techniques had been construct

for operational use in the Network. The dual-shaped reflector design enhanced the rad

performance of the antenna, while the beam waveguide configuration greatly facilitat

maintenance and operation of the microwave receivers and transmitters. Using a seri

of additional secondary reflectors to relocate the focal point into a stationary room belo

the main dish, the BWG design feature enabled these critical components to be moun

ed in a fixed environment rather than in the more conventional type of moving an

tipping enclosure mounted on the antenna itself. 

Beam waveguide antennas had been used for many years in Earth communications sate

lite terminals where ease of maintenance and operation outweighed the consideration 

losses introduced into the microwave signal path by the additional microwave-reflectin

mirrors. For deep space applications, however, where received signal power levels we

orders of magnitude smaller, any losses in the signal path were a matter of great co

cern, and the losses associated with BWG designs kept such antennas out of consideratio

for DSN purposes for many years. Researchers in the DSN Advanced Systems Progra

nevertheless pursued the idea of BWG antennas for the DSN and, by 1985, were read

to conduct a collaborative experiment with the Japanese Institute for Space an

Aeronautical Sciences (ISAS) using its new 64-m beam waveguide antenna at Usud

Japan. Using one of the DSN’s low-noise microwave receivers installed on the Usu

antenna to receive a signal from the International Cometary Explorer (ICE) spacecra

the researchers made very precise measurements of the microwave losses, or degradatio

of the downlink signal. 

The results of the experiment were very surprising. The measured losses, attributable 

the BWG design, were much smaller than expected, exhibiting similar performance 

zenith and better performance at low-elevation angles; they confirmed the efficacy of th

BWG configuration.

Encouraged by this field demonstration, researchers sponsored by the Advanced System

Program moved forward with the construction of a prototype BWG antenna for pote

tial application in the Network.

This new prototype BWG antenna was built at the Venus site at Goldstone and replac

the aging 26-m antenna that had served for many years as a field test site for techno

ogy research and development (R&D) programs. The designers used microwave opti

analysis software, an evolving product of the Advanced Systems Program, to optimi

the antenna for operation over a wide range of current and future DSN operating fr

464

Uplink-Downlink: A History of the Deep Space Networ
quency bands. When completed, the antenna successfully demonstrated its ability 

operate effectively at S-band, X-band, and Ka-band (approximately 2, 8, and 32 GH

respectively). Figure 7-5 shows the completed BWG antenna, and Figure 7-6 shows th

interior of the equipment room below the antenna structure.

46

The Advance of Technology in the Deep Space Network

Figure 7-5. A 34-meter beam waveguide antenna at Goldstone Technology Development Sit

DSS 13.
The various frequencies and modes of operation for the BWG antenna were selected b

rotating the single microwave mirror at the center of this room. Lessons learned b

Advanced Systems Program personnel in the construction and evaluation of this ante

na were incorporated into the design of the operational BWG antennas for the Networ

with the result that the performance of these somewhat exceeded that of the prototyp

especially at the lower frequencies. A selection of technical references related to gre

antennas of the DSN can be found in section 2 of the appendix at the end of the boo

466

Uplink-Downlink: A History of the Deep Space Networ

Figure 7-6. Stationary equipment room below the BWG antenna. 
Forward Command/Data Link (Uplink)

The large antennas of the DSN are used for transmission of radio signals carrying instru

tions and data to the spacecraft, as well as for reception of signals. Getting data to dista

spacecraft safely and successfully requires that substantial power be transmitted from th

ground and directed in a narrow beam at the spacecraft. For most “normal” situation

the compatible design of spacecraft and the DSN is such that power of about 2 kW 

20 kW is adequate. However, situations in space are not always normal. Unexpect

events can redirect a spacecraft’s main antenna away from Earth, leaving only a low-ga

or omnidirectional antenna capable of receiving anything from Earth. Transmitter pow

of up to 400 kW at S-band can be sent from the 70-m antenna during attempts 

regain contact with a spacecraft in such an emergency situation.

The initial design and evaluation of R&D models of the high-power transmitters an

their associated instrumentation was carried out under the Advanced Systems Program

Much of the essential field testing was carried out as part of the planetary radar expe

iments. This cooperative and productive arrangement provided a realistic environme

for testing without exposing an inflight spacecraft to an operational unqualified uplin

transmission. Later, DSN engineers implemented fully qualified operational versions 

these transmitters in the Network at all sites. 

The pointing of the narrow forward link signal to the spacecraft is critical, especial

when making initial contact without having received a signal for reference, as is typic

in emergency situations. The beamwidth of the signal from the 70-m antenna at S-ban

is about 0.030 degrees, while that of the 34-m antenna at X-band is about 0.017 degree

Achieving blind pointing to that precision requires a thorough understanding of th

mechanics of the antenna, including the effects of gravity and wind on the dish an

specifics of the antenna bearing and positioning mechanisms, as well as knowledge 

the spacecraft and antenna positions, atmospheric refraction, and other interferences.

Forward link data delivered to a spacecraft, if incorrectly interpreted, have the potent

for causing that spacecraft to take undesirable actions, including some that could resu

in an emergency situation for the spacecraft. To guard against that possibility, the fo

ward link signal is coded with additional redundant data that allow the spacecraft da

system to detect or correct any corruption in that signal. Operating on the presum

tion that it is always better to take no action than to take an erroneous one, the forwa

link decoding accepts only data sets for which the probability of error is extremely sma

and it discards those that cannot be trusted. A selection of technical references relat

46

The Advance of Technology in the Deep Space Network
to the forward command/data link (uplink) can be found in the section 3 of the appe

dix at the end of the book.

Return Telemetry/Data Link (Downlink)

Throughout the Network, the stations use the same antennas for both the forward lin

and the return data-link signals. Because the strength of a signal decreases as the squa

of the distance it must travel, these two signals may differ in strength by a factor 

1024 in a single DSN antenna. Isolating the return signal path from interference by th

468

Uplink-Downlink: A History of the Deep Space Networ

Figure 7-7. Dichroic (frequency-selective) reflector developed under Advanced Systems Progra
much stronger forward signal poses a significant technical challenge. Normally, these tw

signals differ somewhat in frequency, so at least a part of this isolation can be accom

plished via dichroic or frequency-selective reflectors. These reflectors (Figure 7-7) cons

of periodic arrays of metallic/dielectric elements tuned for the specific frequencies th

either reflect or pass the incident radiation. These devices must not only be frequenc

selective, but they must also be designed to minimize the addition of extraneous rad

noise picked up from the antenna and its surroundings, which would corrupt the incre

ibly weak signals collected by the antenna from the desired radio source in deep spac

The DSN Advanced Systems Program developed the prototypes for almost all the refle

tors of this type in current use in the Network. As an adjunct to this work, powerf

microwave analytical tools that can be used to affix design details for almost any co

ceivable dichroic reflector applicable to the frequency bands of the DSN were also develop

under the Program.

Low-Noise Amplifiers

The typical return data link signal is incredibly small and must be amplified before 

can be processed and the data itself reconstructed. The low-noise amplifiers that resi

in the antennas of the DSN are the most sophisticated in the world and provide th

amplification while adding the least amount of noise of any such devices.

Known as traveling-wave masers (TWMs), the quietest (in terms of adding radio nois

of these operational devices amplify signals that are propagated along the length of 

tuned ruby crystal. Noise in a TWM depends upon the physical temperature of th

crystal, and those in operation in the DSN operate in a liquid helium bath at 4.2 kelvi

(Zero kelvin is equivalent to a temperature of minus 273.18 Celsius. Therefore, the tem

perature of the helium bath is equivalent to approximately minus 269 Celsius.) Th

practical amplifiers for the DSN were invented by researchers at the University of Michiga

and early development of these amplifiers was carried out under the DSN Advanc

Systems Program, as were many improvements throughout the Network’s history. Th

quietest amplifiers in the world today (Figure 7-8), which operate at a physical tem

perature of 1.2 kelvin, were developed by the DSN Advanced Systems Program an

demonstrated at the Technology Development Field Test Site, DSS 13.

46

The Advance of Technology in the Deep Space Network
Some of the low-noise amplifie

in the DSN today are n

TWMs, but a special kind 

transistor amplifier (Figure 7-

using high-electron mobili

transistors (HEMTs) in amplifie

cooled to a physical temperatu

of about 15 kelvin. 

Developed initially at the Un

versity of California at Berkele

such amplifiers were quick

adopted by the scientific com

munity for radio astronom

applications. This, in tur

spawned the JPL developme

work that was carried out via co

laboration involving JPL and t

DSN Advanced Systems Program

radio astronomers at the Nation

Radio Astronomy Observato

(NRAO), and device developers 

General Electric. This work bu

upon progress in the commerc

sector with uncooled transist

amplifiers. In the 2-GHz DS

band, the cooled HEMT amp

fiers are almost as noise-free as t

corresponding TWMs, and t

refrigeration equipment needed 

cool the HEMTs to 15 kelvin is much less troublesome than that for the TWMs. Primar

for this reason, current development efforts in the DSN Advanced Technology area a

focused on improving the noise performance of the HEMT amplifiers for the higher DS

frequency bands.

The first DSN application of the cooled HEMT amplifiers came with the outfitting 

the NRAO Very Large Array (VLA) in Socorro, New Mexico, for collaborative suppo

of the Voyager-Neptune Encounter. The VLA was designed for mapping radio emissio

from distant stars and galaxies and consists of 27 antennas, each 25 meters in diam

470

Uplink-Downlink: A History of the Deep Space Networ

Figure 7-8. Ultra-low-noise amplifier (ULNA) at DSS 13.
ter, arranged in a tri-axial configuration. Within the funding constraints, only a sm

part of the VLA could be outfitted with TWMs, whereas HEMTs for the entire arr

were affordable and were expected to give an equivalent sensitivity for the combined fu

array. In actuality, technical progress with the HEMTs under the Advanced System

Program during the several years taken to build and deploy the needed X-band (8-GH

amplifiers resulted in better performance for the fully equipped VLA than would ha

been possible with the VLA partially equipped with the more expensive TWMs. Sin

that time, many of the DSN operational antennas have had cooled HEMT amplifie

installed for the 2-GHz and 8-GHz bands. A selection of technical references related 

return telemetry (downlink) can be found in section 4 of the appendix at the end 

the book.

47

The Advance of Technology in the Deep Space Network

Figure 7-9. High-electron mobility transistor (HEMT) low-noise microwave amplifier.
Phase-Lock Tracking

Once the first stages of processing in the low-noise amplifiers are completed, there a

still many transformations needed to convert the radio signal sent from a spacecraft in

a replica of the data stream originating on that spacecraft. Some of these transform

tions are by nature analog and linear; others are digital with discrete quantification. A

must be performed with virtually no loss in fidelity in order for the resultant data strea

to be of practical use.

Typically, the downlink signal consists of a narrow-band “residual carrier” sine wav

together with a symmetric pair of modulation sidebands, each of which carries 

replica of the spacecraft data. (Specifics of the signal values vary greatly, but are n

essential for this general discussion.) If this signal is cross-correlated with a pure ide

tical copy of the residual carrier, the two sidebands will fold together, creating 

low-frequency signal that contains a cleaner replica of the spacecraft data than eith

sideband alone. Of course, such a pure copy of the carrier signal does not alread

exist; it must be created, typically via an adaptive narrow-band filter known as 

phase-locked loop. The recreated carrier reference is thus used to extract the sid

bands. The strength of the resultant data signal is diminished to the extent that th

local carrier reference fails to be an identical copy of the received residual carrie

Noise in the spectral neighborhood of the received residual carrier and dynamic var

ations in the phase of the carrier itself limit the ability to phase-lock the local referen

to it.

These dynamic variations are due predominantly to the Doppler effect in play betwee

a distant spacecraft and the DSN antenna on the surface of a spinning Earth. The va

ations interfere with the return data link process, but they themselves provide for a rad

location function. Over the years, the DSN Advanced Systems Program has contribut

significantly to the design for the phase-locked loops and to the knowledge of phas

coherent communications, and thus to the performance of the operational DSN. 

selection of technical references related to phase-lock tracking can be found in sectio

5 of the appendix at the end of the book.

Synchronization and Detection

Further steps in converting a spacecraft signal into a replica of the spacecraft data strea

are accomplished by averaging the signal over brief intervals of time that correspond 

each symbol (or bit) transmitted from the spacecraft and by sampling these averages 

create a sequence of numbers, often referred to as a “symbol stream.” These averag

472

Uplink-Downlink: A History of the Deep Space Networ
must be precisely synchronized with the transitions in the signal as sent from the spac

craft so that each contains as much as possible of the desired symbol and as little 

possible of the adjacent ones. Usually, a subcarrier, or secondary carrier, is employed 

shape the spectrum of the spacecraft signal, and it must be phase-tracked and remov

prior to the final processing of the data itself. The Network contains several differe

generations of equipment that perform this stage of processing. Designs for all of the

have their roots in the products of the DSN Advanced Systems Program. The olde

current equipment is of a design developed in the late 1960s by a partnership betwee

the DSN Advanced Systems Program and the DSN implementation programs. Th

equipment is mostly analog in nature and, while still effective, is subject to compone

value shifts with time and temperature, and thus requires periodic tending and adjus

ments to maintain desired performance.

As digital devices became faster and more complex, it became possible to develop di

ital equipment that could perform this stage of signal processing. Digital demodulatio

techniques were demonstrated by the Advanced Systems Program in the early 1970s 

an all-digital ranging system. Similar techniques were subsequently employed for da

detection in the second generation of the Demodulator-Synchronizer Assembly. A sele

tion of technical references related to data synchronization and detection can be foun

in section 6 of the appendix at the end of the book.

A Digital Receiver

Rapid evolution of digital technology in the 1980s led researchers to explore the app

cation of digital techniques to various complex processes found in receiving systems su

as those used in the Network. The processes of filtering, detection, and phase-lock ca

rier tracking, formerly based on analog techniques, were prime candidates for the ne

digital technology.

In this context, the Advanced Systems Program supported the development of an a

digital receiver for Network use. Known as the Advanced Receiver (ARX), th

developmental model embodied most of these new ideas and demonstrated capabi

ties far exceeding those of the conventional analog receivers then installed througho

the Network.

Encouraged by the performance of the laboratory model, an engineering prototype w

built and installed for evaluation in an operational environment at the Canberra, Austral

Complex. Tests with the very weak signal from the Pioneer 10 spacecraft, then approac

ing the limits of the current DSN receiving capability, confirmed the designe

47

The Advance of Technology in the Deep Space Network
performance and, incidentally, significantly exten

ed the working life of that spacecraft.

As a result of these tests, the DSN decided to pr

ceed with the implementation of a new operation

receiver for the Network that would be based o

the design techniques demonstrated by the ARX

The new operational equipment, designated th

Block V receiver (BVR), would include all of th

functions of the existing receiver in addition to se

eral other data processing functions, such 

demodulation and synchronization, formerly ca

ried out in separate units. 

As the older generation receivers were replaced wi

the all-digital BVR equipment, the Netwo

observed a general improvement in weak signal trac

ing performance and operational reliability. Th

receiver replacement program was complet

throughout the Network by 1998. A selection 

technical references related to digital receivers ca

be found in section 7 of the appendix at the en

of the book.

Encoding and Decoding

The data generated by science instruments must 

reliably communicated from the spacecraft to th

ground, despite the fact that the signal received 

extremely weak and that the ground receiver co

rupts the signal with additive noise. Even wi

optimum integration and threshold detection, ind

vidual bits usually do not have adequate signal ener

to ensure error-free decisions. To overcome this pro

lem, structured redundancy (channel encoding) 

added to the data bit-stream at the spacecra

Despite the fact that the individual “symbols” resu

ing from this encoding have even less energy at th

receiver, the overall contextual information, us

474

Uplink-Downlink: A History of the Deep Space Networ

Figure 7-10. The Advanced Receiver

(ARX) as used to track the Pioneer

10 spacecraft.
properly in the decoding process on the ground, results in more reliable detection 

the original data stream.

High-performance codes to be used for reliable data transfer from spacecraft to DS

were identified by research performed under the Advanced Systems Program and adop

ed for standard use in the Network while the search for even more powerful and efficie

codes continued. New, more efficient block codes, which made better use of the lim

ed spacecraft transmitter power by avoiding the need to transmit separate synchronizin

signals, were developed under the DSN Advanced Systems Program and first demo

strated on the Mariner 6 and 7 spacecraft in 1969. By putting the extra available spacecra

transmitter power into the data-carrying signal, the new block code enabled the retu

of the Mars imaging data at the astonishing (for the time) rate of 16,200 bits per se

ond, an enormous improvement over the 270-bps data rate for which the basic missio

had been designed. Of course, conversion of the encoded data stream back to its ori

inal error-free form required a special decoder. The experimental block decoder, develop

under the same program for this purpose, formed the basis for the operational bloc

decoders implemented in the Network as part of the Multimission Telemetry Syste

shortly thereafter.

While the JPL designers of the Mariner spacecraft were pursuing the advantages 

block-coded data, the designers of the Pioneer 9 spacecraft at the Ames Research Cent

(ARC) were looking to very complex convolutional codes to satisfy their scientists. Th

scientists agreed to accept intermittent gaps in the data caused by decoding failure 

exchange for the knowledge that successfully decoded data would be virtually erro

free. In theory, a convolutional code of length k = 25 would meet the requiremen

but it had a most significant drawback. The decoding process was (at the time) extrao

dinarily difficult. Known technically as “sequential decoding,” this was a continuo

decoding operation rather than the “one block at a time” process used by the DSN f

decoding the Voyager data.

The original plan was to perform the decoding operation for Pioneer 9 in non-real-tim

at ARC, using tape-recorded data provided by the DSN. However, Pioneer enginee

working in conjunction with the DSN Advanced Systems Program explored and demo

strated the potential for decoding this code in real time via a very-high-speed engineerin

model sequential decoder. With the rapid evolution in capability of small computers, 

became apparent that decoding Pioneer’s data in such computers was both feasible an

economical. Subsequent implementation of sequential decoding in the Network was don

via microprogramming of a small computer, guided by the knowledge gained via th

efforts of the Advanced Systems Program. The subsequent Pioneer 10 and 11 spacecra

47

The Advance of Technology in the Deep Space Network
flew with a related code of length k = 32 and were supported by the DSN in a com

puter-based decoder.

The DSN standard code, flown on Voyager and Galileo, consisted of a short convol

tional code that was combined with a large block-size Reed-Solomon code. The standa

algorithm for the decoding of convolutional codes was devised in consultation with JP

researchers and demonstrated by simulations performed under the Advanced System

Program. Prototypes of the decoding equipment were fabricated and demonstrated 

JPL, also with the support of the Advanced Systems Program.

The application of coding and decoding technology in the DSN was paced by the ev

lution of digital processing capability. At the time of the Voyager design, a convolution

code of length k = 7 was chosen as a compromise between performance and decodin

complexity, which would grow exponentially with code length. Equipment was impl

mented around the DSN to handle this code from Voyager and subsequently from Magella

Galileo, and others. Modern digital technology has permitted the construction of mu

more complex decoders, and a code of length k = 15 was devised with the support 

the Advanced Systems Program. This code was installed as an experiment on the Galil

spacecraft shortly before its launch. The corresponding prototype decoder was comple

ed soon afterward. Though not used for Galileo because of its antenna problem, th

more complex decoder was implemented around the Network for support of the Cassi

and subsequent missions.

Efforts of the Advanced Systems Program provided the understanding of telemetry pe

formance to be expected with the use of these codes. Figure 7-11 displays the reliabili

of the communication (actually, the probability of erroneous data bits) as it depen

upon the spacecraft signal energy allocated to each data bit for uncoded communic

tion and three different codes.

Research on new and even more powerful coding schemes, such as turbo codes, co

tinued to occupy an important place in the Advanced Systems Program. Turbo cod

are composite codes made up of short-constraint-length convolutional codes and a da

stream interleaver. The decoding likewise consists of decoders for the simple compone

codes, but with an iterative sharing of information between them. These codes, whi

push hard on the fundamental theoretical limits to signal detection, can result in almo

a full decibel of performance gain over the best previous concatenated coding system

A selection of technical references related to data encoding and decoding can be foun

in section 8 of the appendix at the end of the book.

476

Uplink-Downlink: A History of the Deep Space Networ
Data Compression 

Source encoding and data compression are not typically considered a part of the DSN

downlink functions, but the mathematics that underlie coding and decoding are a cou

terpart of those that guide the development of data compression. Simply stated, chann

encoding is the insertion of structured redundancy into a data stream, while data com

pression is the finding and removal of intrinsic redundancy. Imaging data are often high

47

The Advance of Technology in the Deep Space Network

Figure 7-11. Telemetry communication channel performance for various coding schemes. T

first set of curves shows the Voyager k = code, both alone and in combination with the Ree

Solomon code. The second set of codes illustrates the k = 15 code, which was to be demonstrat

with Galileo’s original high-rate channel, shown alone and in combination with the Reed-Solom

code, either as constrained by the Galileo spacecraft data system (I = 2) or in ideal combinatio

The third set shows the k = 14 code, devised by the Advanced Systems Program researchers 

the actual Galileo low-rate mission, both alone and in combination with the selected variable-redu

dancy Reed-Solomon code and a complex four-stage decoder. The added complexity of the code

which has its greatest effect in the size of the ground decoder, clearly provides increased reliab

ty for correct communication. 

1x10-1

1x10-2

1x10-3

1x10-4

1x10-5

1x10-6

1x10-7

1x10-8

Eb/No(dB)

Bit Error Rate (BER)

-3 -2 -1 0 1 2 3 4 5 6 7 8

theoretical

limit

(15, 1/4)

concat.

(ideal)

(14, 1/4)

concat.

4-stage

(l=8)

(15, 1/4)

concat.

(l=2)

(7, 1/2)

concat.

(ideal)

(7, 1/2)

convolutional

uncoded (14, 1/4)

convolutional (15, 1/4)

convolutional
redundant and can be compressed by factors of at least two, and often four or mor

without loss in quality. For Voyager, two influences led to a factor-of-two increase in th

number of images returned from Uranus and Neptune. The first was the effecting of 

very simplified image-compression process constrained to fit into available onboard mem

ory. The second improvement involved corresponding changes to the channel coding

The success of data compression technology in enhancing the data return from th

Voyager missions firmly established the technique as an important consideration in th

design of all future planetary downlinks. The original telecommunication link design f

the Galileo spacecraft used data compression to almost double the amount of imagin

data that the spacecraft could transmit from its orbital mission around Jupiter. The fa

ure of the spacecraft’s high-gain antenna prior to Galileo’s arrival at Jupiter prompted a

intense effort to find even more complex data compression schemes that would reco

er some of the Jupiter imaging data that otherwise could not have been returned. 

selection of technical references related to data compression can be found in section 

of the appendix at the end of the book.

Arraying of Antennas

The technique of antenna arraying, as practiced in the Deep Space Network, made u

of the physical fact that a weak radio signal from a distant spacecraft that is receiv

simultaneously by several antennas at different locations is degraded by a component 

radio noise that is independent of each receiving station. By contrast, the spacecraft si

nal itself is dependent, or coherent, at each receiving site. In theory, therefore, the pow

of the signal, relative to the power of the noise, or signal to noise ratio, (SNR) cou

be improved by combining the individual antennas in such a way that the cohere

spacecraft signals were reinforced, while the independent or non-coherent noise com

ponents were canceled out.

In practice, this involved a complex digital process for compensating for the time, 

phase, delays caused by the different distances between each station and the spacecra

It also called for compensating for differing distances between the various antenna loc

tions and the common station where the combining function was carried out. Th

technique became known as antenna arraying, and the digital processing function th

realized the theoretical “gain” of the entire process was called “signal combining.” 

By 1970, conceptual studies had described and analyzed the performance of several le

els of signal combining and two of these schemes, carrier and baseband combining, we

of potential interest to the Network. Both techniques involved compensation for th

478

Uplink-Downlink: A History of the Deep Space Networ
phase delays caused by the various locations of the arrayed antennas. The difference l

in the frequency at which the combining function was performed. “Carrier” combinin

was done at the carrier frequency of the received signal, while “baseband” combinin

was carried out at the frequencies of the subcarrier and data signal that modulated 

Each had its advantages and disadvantages, but baseband combining proved easier 

implement and was, obviously, tried first.

The “arraying and signal combining” concept was first developed and demonstrated 

1969 and 1970 by J. Urech, a Spanish engineer working at the Madrid tracking st

tion. Using signals from the Pioneer 8 spacecraft and a microwave link to connect tw

26-m stations located 20 km apart (DSS 61 and DSS 62), he succeeded in demo

strating the practical application of the principle of baseband combining in the Netwo

for the first time. Because of the low baseband frequency of the Pioneer 8 data strea

(8 bits per second), as well as the close proximity of the antennas, no time-delay com

pensation was necessary.

Within the bounds of experimental error, this demonstration confirmed the R&D th

oretical estimates of performance gain and encouraged the Advanced Systems researche

to press forward with a more complex form of baseband combining at a much high

data rate (117 kilobits per second) in real time.

The demonstration took place at Goldstone in September 1974, using the downlin

signals from the Mariner-Venus-Mercury (MVM) spacecraft during its second encount

with the planet Mercury. Spacecraft signals from the two 26-m antennas, DSS 12 an

DSS 13, were combined in an R&D combiner with signals from the DSS 14 64-

antenna in real time at 117 kbps. The less-than-predicted arraying gain obtained in th

demonstration (9 percent versus 17 percent) was attributed to small differences in pe

formance between key elements of the several data-processing systems involved in th

test. Although this experience demonstrated both the practical difficulty of achieving fu

theoretical gain of an antenna arrayed system and the critical effect of very small va

ations in the performance of its components, it also established the technical feasibili

of baseband arraying of very weak high-rate signals.

In 1977, with the lessons learned from these demonstrations as background, the DS

started to develop an operational arraying capability for the Network. The Voyager 1 an

2 Encounters with Saturn in 1980 and 1981 would be the first to use the arraying 

the Network. A prototype baseband real-time combiner (RTC), based on the analy

and design techniques developed by the earlier R&D activity, was completed in the f

of 1978. Designed to combine the signals from DSS 12 and DSS 14 at Goldstone, 

47

The Advance of Technology in the Deep Space Network
was used with varying degrees of success to enhance the signals from the Voyagers 

Jupiter in March and July of 1979 and the Pioneer 11 Encounter of Saturn in Augu

and September of that year. 

Like the previous demonstration, this experience emphasized the critical importance 

having all elements of the array-receivers, antennas, and instrumentation operating pr

cisely according to their specified performance capabilities. With this very much in min

the DSN proceeded to the design for operational versions of the RTC for use at 

three complexes to support the Voyager 1 and 2 Encounters of Saturn. The operation

versions of the RTC embodied many improvements derived from the experience wi

the R&D prototype version. By mid-August 1980, they were installed and being us

to array the 64-m and 34-m antennas at all three complexes as Voyager 1 began its fa

Encounter operations. During this period, the average arraying gain was 0.62 dB, abo

15 percent greater than that of the 64-m antenna alone. While this was good, improv

ment came slowly as more rigorous control and calibration measures for the array elemen

were instituted throughout the Network. By the time Voyager 2 reached Saturn in Augu

1981, these measures, supplemented with additional training and calibration procedure

had paid off. The average arraying gain around the Network increased to 0.8 dB (appro

imately 20 percent), relative to the 64-m antenna alone. This was clearly a most satisfacto

result and the best up to that time. Antenna arraying had become a permanent add

tion to the capability of the Network.

While researchers working within the Advanced Systems Program continued to explo

new processes for arraying antennas, engineers within the DSN took advantage of th

long flight time between the Voyager Saturn and Uranus Encounters to refine th

existing RTC configuration. Over the next five years, the formerly separate data-pr

cessing functions of combining, demodulation, and synchronization were integrat

into a single assembly. This integration facilitated improvements in performance, st

bility, and operational convenience. By the time Voyager 2 approached Uranus in 198

the new Baseband Assemblies (BBAs), as they were called, had been installed at 

three Complexes. In addition, a special version of the basic four-antenna BBA w

installed at the Canberra Complex. This provided for combining the Canberra arr

of one 64-m and two 34-m antennas with signals from the 64-m Parkes Radio Telescop

200 km distant (Figure 7-12).

In January 1986, this arrangement was a key factor in the successful return of Voyag

imaging data from the unprecedented range of Uranus. But even greater achievemen

in antenna arraying lay ahead.

480

Uplink-Downlink: A History of the Deep Space Networ
In 1989, the DSN used a similar arrangement with great success to capture the Voyag

imaging data at a still greater range—from Neptune. This time the Goldstone 70-m an

34-m antennas were arrayed with the 27 antennas of the Very Large Array (VLA) (Figu

7-13) of the National Radio Astronomy Observatory at Socorro, New Mexico.

48

The Advance of Technology in the Deep Space Network

Figure 7-12. The 64-m antenna of the Radio Astronomy Observatory, Parkes, Australia.
DSN support for the Voyager Encounter of Uranus was further augmented by the Canberr

Parkes array in Australia, which the DSN had reinstated with the addition of new BBA

new 34-m antennas, and the upgraded 70-m antenna.

The success of these applications of the multiple-antenna arraying technique provid

the DSN with a solid background of operational experience. The DSN drew heavily o

this experience a few years later, when it was called upon to recover the science da

from Galileo after the failure of the spacecraft’s high-gain antenna in 1991. Togeth

with the data compression and coding techniques discussed earlier, the Network

Canberra/Parkes/Goldstone antenna arrays succeeded in recovering a volume of data tha

according to the Galileo project, was equivalent to about seventy percent of the orig

nal mission.

With time, arraying of multiple antennas within Complexes, between Complexes, 

between international space agencies came into general use as a means to enhance th

downlink capability of the Network. In the latter years of the century, most of th

enhancements to the arraying in the DSN were driven by implementation and oper

482

Uplink-Downlink: A History of the Deep Space Networ

Figure 7-13. The Very Large Array (VLA) of the National Radio Astronomy Observatory (NRA

at Socorro, New Mexico.
tional considerations rather than by new technology, although the Advanced System

Program continued to explore the boundaries of performance for various alternative arra

ing architectures and combining techniques. A selection of technical references relat

to antenna arraying can be found in section 10 of the appendix at the end of the boo

Radio Metric Techniques

In addition to being able to exchange forward and return link data with an explorin

spacecraft, it is equally important to know the precise location of the spacecraft and 

velocity (speed and direction). Information about the position and velocity of the spac

craft can be extracted from the one-way or two-way radio signals passing between th

spacecraft and the DSN. When these data are extracted by appropriate processing an

further refined to remove aberrations introduced by the propagation medium along th

radio path between spacecraft and Earth, it can be used for spacecraft navigation.

Radio metric techniques similar to those used for spacecraft navigation can also be us

for more explicit scientific purposes, notably radio science, radio astronomy, and rad

interferometry on very long baselines (VLBI).

Since its inception, the DSN Advanced Systems Program has worked to develop effe

tive radio metric tools, techniques, observing strategies, and analysis techniques th

furthered the DSN pre-eminence in these unique fields of science. In more recent time

the Advanced Systems program demonstrated the application of Global Positioning Syste

technology to further refinement of radio metric data generated by the DSN. A sele

tion of technical references on radio metric tools can be found in section 11 of th

appendix at the end of the book.

Doppler and Range Data 

If the Earth and the spacecraft were standing still, the time taken for a radio signal 

travel from the Earth to the spacecraft and back would be a measurement of the d

tance between them. This is referred to as the round-trip light time (RTLT). Howev

since the Earth and the spacecraft are both in motion, the RTLT contains both po

tion and velocity information, which must be disentangled through multiple measuremen

and suitable analysis. The precision at which such measurements can be obtained is lim

ited by the precision of the time-tag marker to the radio signals, and by the streng

of the signal in proportion to the noise mixed with it, or by the signal-to-noise rat

(SNR).

48

The Advance of Technology in the Deep Space Network
Precise measurements of changes to this light time are far easier to obtain via obser

ing the Doppler effect resulting from the relative motions. Such measurements a

mechanized via the phase-locked loops in both spacecraft and ground receivers usin

the spacecraft’s replica of the forward link residual carrier signal to generate the retu

link signal, and counting the local replica of the return link residual carrier again

the original carrier for the forward link signal. The raw precision of these measur

ments is comparable to the wavelength of the residual carrier signal, e.g., a few centimete

for an X-band signal (8 GHz). Numerous interesting error sources tend to corru

the accuracy of the measurement and the inferred position and velocity of the spac

craft, and they have provided significant technical challenge for work under the Advanc

Systems Program.

The observed Doppler contains numerous distinct components, including the very si

nificant rotation of Earth. As Earth turns, the position of any specific site on the surfa

describes a circle, centered at the spin axis of the Earth, falling in a plane defined b

the latitude of that site. The resultant Doppler component varies in a diurnal fashio

with a sinusoidal variation, which is at its maximum positive value when the spacecra

is first observable over the eastern horizon. Its corresponding negative value occurs 

approach to the western horizon. A full-pass Doppler observation from horizon to ho

zon can be analyzed to extract the apparent spacecraft position in the sky, although th

determination is somewhat weak near the equatorial plane. Direct measurements of th

RTLT are useful for resolving this difficulty.

Three distinct generations of instruments designed to measure the RTLT were deve

oped by the Advanced Systems Program and used in an ad hoc fashion for spacecra

support before a hybrid version was designed and implemented around the DSN. Th

third instrument designed, the Mu-II Ranging Machine, was used with the Viking Lande

in a celestial mechanics experiment, which provided the most precise test, up to th

time, of the general theory of relativity.

These devices function by imposing an additional “ranging” modulation signal on th

forward link, which is copied on the spacecraft (within the limits imposed by nois

and then imposed on the return link. The ranging signal is actually a very long per

od-coded sequence that provides the effect of a discrete time tag. The bandwidth 

the signal is on the order of 1 MHz, giving the measurement a raw precision of 

few hundred meters, resolvable with care to a few meters. Among other features, th

Mu-II Ranging Machine included the first demonstrated application of the digit

detection techniques that would figure strongly in future developments for the DSN

484

Uplink-Downlink: A History of the Deep Space Networ
Timing Standards

The basic units of measurement for all radio metric observations, Doppler or range, deri

from the wavelength of the transmitted signal. Uncertainties or errors in knowledge of th

wavelength are equivalent to errors in the derived spacecraft position. The need for acc

rate radio metrics has motivated the DSN Advanced Systems Program to develop some 

the most precise, most stable frequency standards in the world. While the current suite 

hydrogen maser frequency standards in the DSN field sites was built outside of JPL, t

design is the end product of a long collaboration in technology development, with resear

units being built at JPL under the DSN Advanced Systems Program and elsewhere. 

Continued research under the Advanced Systems Program for improved frequency sta

dards resulted in the development of a new linear ion trap standard (Figure 7-14) th

48

The Advance of Technology in the Deep Space Network

Figure 7-14. The new linear ion trap (LIT) standard.
offered improved long-term stability of a few parts in 1016, as well as simpler and ea

er maintenance than that required by the hydrogen masers.

Work was under way to implement the LIT standard in the DSN, while research effor

continued for improvements that could be transferred to field operation in the futur

A selection of technical references related to timing standards can be found in sectio

12 of the appendix at the end of the book.

Earth Rotation and Propagation Media

Radio metric Doppler and range data enable the determination of the apparent locatio

of a spacecraft relative to the position and attitude of the rotating Earth. Earth, how

ever, is not a perfectly rigid body with constant rotation, but contains fluid componen

as well, which slosh about and induce variations in rotation of perhaps a few millise

onds per day. Calibration of Earth’s attitude is necessary so that the spacecraft’s positio

in inertial space can be determined—a necessary factor in navigating the spacecraft towa

a target planet. Such calibration is available via the world’s optical observatories an

with greater precision, via radio techniques, which will be discussed further in the se

tions entitled “VLBI and Radio Astronomy” and “Global Positioning System.”

The interplanetary media along the signal path between Earth and the spacecraft affe

the accuracy of the Doppler and range observations. The charged ions in the tenuo

plasma spreading out from the Sun, known as the solar wind, bend and delay the rad

signal. Likewise, the charged ions in Earth’s own ionosphere and the water vapor an

other gases of the denser lower atmosphere bend and delay the radio signal. All of the

factors are highly variable because of other factors, such as intensity of solar activity, se

son, time of day, and weather. All factors must be calibrated, modeled, or measured 

achieve the needed accuracy; over the years, the DSN Advanced Systems Program h

devised an increasingly accurate series of tools and techniques for these calibrations. 

selection of technical references related to Earth rotation and propagation can be foun

in section 13 of the appendix at the end of the book.

Radio Science

Radio science is the term used to describe the scientific information obtained from th

intervening pathway between Earth and a spacecraft by the use of radio links. The effec

of the solar wind on the radio signal path interfere with our efforts to determine th

location of the spacecraft, but if the relative motions of Earth and the spacecraft a

modeled and removed from the radio metric data, much of what remains is inform

486

Uplink-Downlink: A History of the Deep Space Networ
tion about the solar wind and, thus, about the Sun itself. Other interfering factors a

also of scientific interest. 

In some situations, the signal path passes close by a planet or other object, and th

signal itself is bent, delayed, obscured, or reflected by that object and its surroundin

atmosphere. These situations provide a unique opportunity for scientists to extract info

mation from the signal about object size, atmospheric density profiles, and other facto

not otherwise observable. Algorithms and other tools devised to help calibrate an

remove interfering signatures from radio metric data for use in locating a spacecra

often become part of the process for extracting scientific information from the sam

radio metric data stream. The precision frequency standards, low-noise amplifiers, an

other elements of the DSN derived from the Technology Program are key factors 

the ability to extract this information with a scientifically interesting accurac

Occasionally, engineering models developed by the Program are placed in the Netwo

in parallel with operational instrumentation for ad hoc support of metric data-gathe

ing for some unique event.

The effects of gravity can also be observed by means of the radio link. Several situ

tions are of interest. If the spacecraft is passing by or in orbit about an object that h

a lumpy, uneven density, that unevenness will cause a variation in the spacecraft’s pat

way that will be observable via the radio metric data. If the radio signal passes near 

massive object such as the Sun, the radio signal’s path will be bent by the intense gra

ity field, according to the theories of general relativity. And in concept, gravitation

waves (a yet-to-be-observed aspect of gravity field theory) should be observable in th

Doppler data from a distant spacecraft. All of these possibilities depend upon the st

bility of the DSN’s precision frequency standards for the data to be scientifically interestin

A selection of references related to radio science can be found in section 14 of the appe

dix at the end of the book.

VLBI and Radio Astronomy

The technical excellence of the current DSN is, at least in part, a result of a long an

fruitful collaboration with an active radio astronomy community at the California Institu

of Technology (Caltech) and elsewhere. Many distant stars, galaxies, and quasars a

detectable by the DSN at radio frequencies. The furthest of these are virtually motio

less and can be viewed as a fixed-coordinate system to which spacecraft and oth

observations can be referenced. Observations relative to this coordinate set help to redu

the distorting effects of intervening material in the radio signal path and uncertainti

in the exact rotational attitude of Earth during spacecraft observations.

48

The Advance of Technology in the Deep Space Network
Little precise information can be extracted by observing these objects one at a tim

and from a single site, but concurrent observation at a pair of sites will determine th

relative position of the two sites referenced to the distant object. The observing tec

nique is known as very long baseline interferometry (VLBI) and was developed by th

research of many contributors, including substantial work by the DSN’s Advanced System

Program. If three sites are used in VLBI pairs and multiple objects are observed, th

positional attitude of Earth and the relative positions of the observed objects can 

determined. If one of the observed is a spacecraft transmitting a suitable signal, its po

tion and velocity in the sky can be very accurately defined. A demonstration of th

technique via the Advanced Systems Program led to operational use for spacecraft suc

as Voyager and Magellan.

VLBI can also be used in conjunction with conventional radio metric data types to pr

vide the calibration for the positional attitude of Earth. Such observations can be ma

without interfering with spacecraft communication except for the time utilization of th

DSN antennas. In addition to determining Earth’s attitude, the observations measu

the relative behavior of the frequency standards at the widely separated DSN sites, an

thus help to maintain their precision performance. Again, demonstration of this cap

bility via the Advanced Systems Program led to routine operational use in the DSN.

Design and development of the DSN equipment and software needed for VLBI sign

acquisition and signal processing (correlation) was carried out in a collaboration invol

ing the Advanced Systems Program, the operational DSN, and the Caltech radio astronom

community. Tools needed to produce VLBI metric observations for the DSN were esse

tially the same as those for interferometric radio astronomy. Caltech received fundin

from the National Science Foundation for this activity, and both Caltech and the DS

shared in the efforts of the design while obtaining products that were substantially be

ter than any that they could have been obtained independently.

Another area of common interest between the DSN and the radio astronomy comm

nity is that of precision wideband spectral analysis. Development efforts of the Advanc

Systems Program produced spectral analysis tools that have been employed by the DS

in spacecraft emergency situations and in examining the DSN’s radio interference env

ronment, and they have served as pre-prototype models for equipment for the DSN

Demonstration of the technical feasibility of the very-wide-band spectral analysis an

preliminary observations by a megachannel spectrum analyzer fielded by the Advanc

Systems Program helped establish the sky survey planned as part of the former SET

(Search for Extraterrestrial Intelligence) Program.

488

Uplink-Downlink: A History of the Deep Space Networ
Another technique (one similar to the use of VLBI for a radio metric reference) is us

if two spacecraft are flown to the same target; the second can be observed relative 

the first, providing better target-relative guidance once the first has arrived at the ta

get. Techniques for acquiring and analyzing such observations have been devised by th

Advanced Systems Program. A selection of technical references related to VLBI and rad

astronomy can be found in section 15 of the appendix at the end of the book.

The Global Positioning System

The Global Positioning System (GPS) is a constellation of Earth-orbiting satellites design

(initially) to provide for military navigation on Earth’s surface. Research under the Advanc

Systems Program showed that these satellites could provide an excellent tool to calibra

and assist in the radio metric observation of distant spacecraft. GPS satellites fly abo

the Earth’s atmosphere and ionosphere in well-defined orbits so that their signals can 

used to measure the delay through these media in a number of directions. With su

able modeling and analysis, these measurements can be used to develop the atmospher

and ionospheric calibrations for the radio path to a distant spacecraft. 

Additionally, since the GPS satellites are in free orbit about Earth, their positions a

defined relative to the center of mass of Earth, and not its surface. They provide anot

er method to observe the uneven rotation of Earth.

GPS techniques can also be used to determine the position of an Earth-orbiting spac

craft relative to the GPS satellites, as long as the spacecraft carries a receiver for the GP

signals. The potential of this technique was initially demonstrated by the Advanc

Systems Program. GPS was subsequently used by the TOPEX/POSEIDON Project f

precise orbit determination and a consequent enhancement of its scientific return. 

selection of technical references related to the GPS can be found in section 16 of th

appendix at the end of the book.

Goldstone Solar System Radar

The Goldstone Solar System Radar (GSSR) is a unique scientific instrument for ma

ing observations of nearby asteroids, the surfaces of Venus or Mars, the satellites 

Jupiter, and other objects in the solar system. Although the GSSR makes use of th

DSN 70-m antenna for its scheduled observing sessions, its receiving, transmitting, an

data-processing equipment is unique to the radar program. The GSSR is a product 

many years of development by the DSN Advanced Systems Program. In the early da

of the DSN, the Advanced Systems Program took ownership of the radar capability 

48

The Advance of Technology in the Deep Space Network
the DSN’s Goldstone, California, site and evolved and nurtured it as a vehicle for deve

oping and demonstrating many of the capabilities that eventually would be needed b

the Network.

Scientific results abounded as well, but they were not its primary product. Timely deve

opment of DSN capabilities was the major result. Preparations for a radar observatio

at the DSN Technology Development Field Site bore many resemblances to those f

a spacecraft planetary encounter, since the radar observations could only be successf

during the few days when Earth and the radar target were closest together.

In the conventional formulation of the radar sensitivity equations, that sensitivity depen

upon the aperture, temperature, power, and gain of the system elements. Here, apertu

refers to the effective size, or collecting area and efficiency, of the receiving antenn

temperature is a way of referring to the noise in the receiving system, where a low

temperature means a lesser noise; power refers to the raw power level from the tran

mitter; and gain is the effective gain of the transmitting antenna, which depends in tu

upon its size, its surface efficiency, and the frequency of the transmitted signal. Whe

the same antenna is used both to transmit and to receive, the antenna size and ef

ciency appear twice in the radar equations.

Significant improvements to the DSN’s capability for telemetry reception were to com

from the move upward in frequency from S-band (2 GHz) to X-band (8 GHz) on th

large 64-m antennas. Performance of these antennas at the higher frequencies and th

ability to successfully point them were uncertain, however, and these uncertainties wou

best be removed by radar observations before spacecraft with X-band capabilities we

launched. The radar had obvious benefit from the large antenna and the higher fr

quency. The first flight experiment for X-band communication was carried out on th

1973 Mariner Venus Mars mission. Successful radar observations from the Goldston

64-m antenna demonstrated that the challenge of operating the large antennas at th

higher X-band frequency could be surmounted.

High-power transmitters were needed by the DSN for its emergency forward link fun

tions but were plagued by problems such as arcing in the waveguide path when pow

densities became too high. High-power transmitters were essential for the radar to “se

at increased distances and with increased resolution. Intense development efforts at th

DSN Technology Development Field Site could take place without interference or ri

to spacecraft support in the Network. Successful resolution of the high-power problem

for the radar under the Advanced Systems Program became the successful implement

tion of the high-power capability needed by the Network for uplink communication

490

Uplink-Downlink: A History of the Deep Space Networ
Low-noise amplifiers were needed by the DSN to increase data return from distant spac

craft. Low-noise amplifiers were essential for the radar to enable it to detect echoes fro

increasingly distant targets or to provide for increased resolution of already detectab

targets. The synergistic needs of both the radar system and the Network led to the deve

opment of the extremely low-noise maser amplifiers that became part of the standa

operational inventory of the DSN.

Digital systems technology was rapidly evolving during this period and would play a

increasing role in the developing DSN. Equipment developed by the Advanced System

Program for its radar application included 1) digital encoders to provide for spati

resolution of parts of the radar echo, 2) computer-driven programmable oscillators 

accommodate Doppler effects on the signal path from Earth to target to Earth, an

3) complex, high-speed digital signal processing and spectrum analysis equipmen

Much of the digital technology learned this way would transfer quickly to other par

of the signal processing work under the Advanced Systems Program and eventual

into the operational DSN. Some of the elements would find direct application, suc

as the programmable oscillators, which became essential for maintaining contact wi

the Voyager 2 spacecraft following a partial failure in its receiver soon after launc

And the signal analysis tools would be called on many times over the years to he

respond to spacecraft emergencies.

Some of the products of the early radar observations (see Figure 7-15) were both sc

entific in nature and essential for providing information for the planning and executio

of NASA’s missions. 

One notable “first” was the direct measurement of the astronomical unit. (One astr

nomical unit (AU) is equal to 1.5 x 108 km, the mean distance between Earth and th

Sun.) It sets the scale size for describing distances in the solar system. The measureme

was made in support of preparations for sending Mariner 2 to Venus and provided 

correction of 66,000 km from conventional belief at that time. It also enabled corre

tions that brought the mission into the desired trajectory for its close flyby of the plane

The GSSR was also used in qualifying potential Mars landing sites for the Viking Lande

and it continues to provide information about the position and motion of the plane

which is used to update the predicted orbits for the planets of the solar system. A sele

tion of technical references related to the Goldstone solar system radar can be found 

section 17 of the appendix at the end of the book.

49

The Advance of Technology in the Deep Space Network
Telecommunications Performance of the Network

The progress of deep space communications capability over the period of forty yea

since the inception of the Network is illustrated in Figure 7-16.

In interpreting the data presented in Figure 7-16, it will be observed that the logarit

mic scale that displays the data rate gives an impression that the early improvements a

more significant than the later improvements. This is because the steps represent fra

tional or percentage increases, rather than incremental increases. The latter would sho

the actual data rate increases, which are much larger in the later improvements. If th

value was proportional to the amount of data, then the display of the incremental increa

es would be more meaningful than the logarithmic display.

492

Uplink-Downlink: A History of the Deep Space Networ

Figure 7-15. First high-resolution radar image of Venus.
Presented this way, however, the figure clearly shows that, from inception though 199

the downlink capability of the Network grew from 10-6 to 106 bits per second, equiv

lent to twelve orders of magnitude.

This remarkable progress is not, of course, solely due to improvements in the Networ

Many of the steps result from “cooperative” changes on the part of both the DSN an

49

The Advance of Technology in the Deep Space Network

Figure 7-16. Profile of deep space communications capability. The timeline on the horizon

axis of the figure covers the first forty years of actual Network operational experience through t

close of the century and extends for a further twenty years to forecast the potential for future improv

ments through the year 2020. The vertical axis displays the growth in space-to-Earth downli

capability of the Network. The downlink capability is given in units of telemetry data rate (bits p

second) on a logarithmic scale and represents the equivalent imaging data rate capability for a ty

ical spacecraft at Jupiter distance (750 million kilometers). Significant events in the history of de

space telecommunications and deep space exploration are appropriately annotated on both axe
the spacecraft. Coding, for example, is applied to the data on the spacecraft and remov

on Earth. A change in frequency has resulted in some of the larger steps shown by cau

ing the radio beam from the spacecraft to be more narrowly focused. Such chan

necessitates equipment changes on both the spacecraft and Earth.

Other steps represent advances that are strictly spacecraft-related, such as increases 

return-link transmitter power or increases in spacecraft antenna size, which improves pe

formance by more narrowly focusing the radio beam from the spacecraft.

Still other steps depict improvements strictly resulting from the DSN, such as reductio

in receiving system temperature, increase in the size of the ground antennas, or use 

arrays of antennas to increase the effective surface area available for collecting sign

power. A selection of technical references related to telecommunications performance ca

be found in section 18 of the appendix at the end of the book.

Cost-Reduction Initiatives

With one exception, the program continued to pursue the same broad themes in th

period, December 1994 to December 1997, that had characterized its earlier work. Th

new theme that began to appear in the program in 1994 was directed at the reductio

of Network operations costs.

A Network automation work area was set up to develop automated procedures to repla

the extremely operator-intensive work of running a spacecraft “pass” over a DSN trac

ing station. This effort soon produced demonstrable results. A fully automated satelli

tracking terminal that could reduce operations costs for near-Earth satellites was demo

strated in 1994. A software prototype that reduced the number of manual inputs for 

typical 8-hour track from 900 to 3 was installed at DSS 13 and used to support K

band operations at that site. Eventually this technology would find its way into th

operational Network. A contract for a new, small deep space transponder offering low

size and power needs, and most importantly lower production costs, was initiated wi

Motorola in July 1995. This became an element in JPL’s future low-cost micro-spac

craft. Development of a space-borne micro-GPS receiver, which offered the promise 

low-cost orbit determination for most low-Earth orbiting spacecraft, was also initiat

in 1995. 

Prototypes of a new class of low-cost, fully automated, autonomous ground stations th

would simplify implementation and operation and reduce the life-cycle cost of trackin

stations in the DSN were introduced in 1995, 1996, and 1997. The first of these te

494

Uplink-Downlink: A History of the Deep Space Networ
minals was designed for tracking spacecraft in low-Earth orbit and was named LEO-

It was enclosed in a radome and mounted on the roof of a building at JPL, where 

accumulated over two years of unattended satellite tracking operations without pro

lems. Prompted by the success of LEO-T, the program undertook a fast-track effort 

develop a similar automated terminal for deep space applications. It would be call

DS-T. The prototype DS-T was to be implemented at the 26-m BWG antenna 

Goldstone. Automation technology was carried one step further into the area of Netwo

operations in 1997 with the introduction of Automated Real-time Spacecraft Navigatio

(ARTSN). In addition to the antenna system, the DS-T included an X-band microwa

system, a 4-kW transmitter, and an electronics rack containing commercial-off-the-she

equipment to carry out all baseband telemetry downlink, command uplink, and Doppl

and ranging functions. It was planned to demonstrate DS-T with Mars Global Survey

early in 1998 and to use this technology (autonomous uplink and downlink) in th

Network with the New Millennium DS-1 spacecraft later that year. A selection of tec

nology references related to cost-reduction initiatives can be found in section 19 of th

appendix at the end of the book.

49

The Advance of Technology in the Deep Space Network
KA-BAND DEVELOPMENT

In the past, the major improvements in the Network’s deep space communications cap

bilities were made by moving the operating frequency to the higher frequency band

Recognizing this, research and development at Ka-band (32 GHz) was started in 198

Initial efforts were directed toward low-noise amplifier development and system bene

studies. However, it was also clear that the performance of existing antennas (which we

designed for much lower frequencies) would severely limit the improvement in pe

formance that could be realized from the higher operating frequency. Accordingly, 

1991, a new antenna specifically designed for research and development at Ka-band w

installed at the DSS 13 Venus site at Goldstone. It would be used as the pathfinder f

development of large-aperture beam waveguide antennas that would, in due course, 

implemented throughout the Network. 

Small imperfections in the surface of an antenna cause larger degradations at Ka-ban

than at lower frequencies, and, because of the narrower beam width, small pointin

errors have a much larger effect. In 1994, improvements in antenna efficiency and 

antenna pointing were made on the research and development Ka-band antenna at DS

13 and on the new operational antenna at DSS 24. These improvements were effect

by the use of microwave holography for precise determination of antenna efficienc

along with a special gravity-compensation system to counteract the effect of gravitation

sag as a function of antenna elevation angle. In a search for further downlink improv

ment, a new feed system consisting of a maximally compact array of seven circul

Ka-band horns was designed and tested at DSS 13. Each horn was connected to a cry

genically cooled low-noise amplifier, a frequency down-converter, an analog-to-digit

converter, and a digital signal processor. The signals from each horn were optimally com

bined in a signal processor and presented as a single output with a quality equivale

to that of a signal from an undistorted antenna. The measured gain in downlink pe

formance was 0.7 dB.

The technology program continued to develop operational concepts that would eve

tually lead to the adoption of Ka-band for deep space missions. Tradeoff studies betwee

X-band and Ka-band showed the overall advantage of Ka-band, taking due account 

the negative effects inherent in its use, to be about a factor of four, or 6 dB, in da

return capability. Obviously, end-to-end system demonstrations were needed to inst

confidence in the new technology. In 1993, the Mars Observer spacecraft carried a no

linear element in its transmission feed to produce a fourth harmonic of the X-ban

signal. The demonstration (called KABLE for Ka-band Link Experiment) provided 

weak Ka-band signal for the tracking antenna at DSS 13. A second demonstratio

496

Uplink-Downlink: A History of the Deep Space Networ
(KABLE II) was conducted using the Mars Global Surveyor mission in 1996. This expe

iment would be used to characterize Ka-band link performance under real flight conditio

and validate the theoretical models derived from the studies mentioned above. 

KABLE-II required additions to the MGS spacecraft radio-transponder to generate 

modulated Ka-band downlink from which the improvements that had been made 

the DSS 13 antenna to reduce pointing errors and improve performance while trackin

a spacecraft at Ka-band could be evaluated. While the main objective of KABLE-II w

to evaluate Ka-band for future operational use, it also served as a testbed for new K

band technology applications in both the flight systems and the ground systems.

In the course of transition to simultaneous X-/Ka-band operation, the DSN needed th

capability to support various combinations of X- and Ka-band uplinks and downlink

These included Ka-band receive only; X-/Ka-band simultaneous receive, with or wit

out X-band transmit; and full X-band transmit/receive simultaneously with Ka-ban

receive/transmit. The technology program developed new microwave techniques usin

frequency-selective surfaces and feed junction diplexers to provide the frequency an

power isolation necessary to realize the performance required by a practical device. 

late 1996, a demonstration at DSS 13 succeeded in showing that these four differe

modes of operation could coexist on a single beam waveguide antenna within accep

able performance limits. This work provided a viable solution to the problem 

simultaneous X-/Ka-band operation on a single antenna; this solution would be nee

ed by the operational network to support the Cassini radio science experiment (sear

for gravitational waves) in 2000.

Recognizing the need for a cheaper, smaller, less power-consuming radio-transponder 

replace the existing device on future deep space missions, the advanced developme

program embarked on a joint program with other JPL organizations to develop the Sm

Deep Space Transponder (SDST). The concept employed Microwave Monolith

Integrated Circuits in the RF circuits and Application Specific Integrated Circuit tec

niques to perform digital signal-processing functions, with a RISC microprocessor 

orchestrate overall transponder operation. The transponder would transmit coherent X

band and Ka-band downlinks and receive an X-band uplink. Besides minimizing productio

costs, the principal design drivers were reduction in mass, power consumption, and vo

ume. The Small Deep Space Transponder was flown in space for the first time aboa

the DS-1 New Millennium spacecraft in July 1998.

With a view to providing a better understanding of the performance of Ka-band lin

relative to X-band links from the vantage point of a spaceborne radio source, the DS

49

The Advance of Technology in the Deep Space Network
technology program engaged in the development of a small low-Earth-orbiting spac

craft called SURFSAT-1. Launched in 1995, the experiment provided an end-to-end te

of Ka-band signals under all weather conditions and DSS 13 antenna elevation angl

as the spacecraft passed over Goldstone. The SURFSAT data was also used for com

parison with the KABLE data received from MGS. Later, the SURFSAT X-band an

Ka-band downlinks were used to great advantage to test and calibrate the DSN’s ne

11-meter antennas prior to their support of the VSOP (HALCA) Orbiting VLBI m

sion in 1996. A selection of technical references related to Ka-band development can 

found in section 20 of the appendix at the end of the book.

Other Technologies

While reduction of Network operating costs and the introduction of Ka-band into th

Network were important features of the Technology Program in the late 1990s, th

were not the only areas of activity. Interagency agreements allowed Wide-Area Different

GPS techniques, originally developed under the technology program for NASA spac

craft orbit determination and DSN Earth platform calibrations, to be made available f

applications within the Department of Transportation and Federal Aviation Administratio

In addition to these other technologies, further advances were made in the areas of ph

tonics and optical communications. A selection of technical references related to oth

technologies can be found in section 21 of the appendix at the end of the book.

Optical Communications Development

Beginning in 1980, the Technology Program supported theoretical analyses that pr

dicted, under certain system and background light conditions typical of deep spa

applications, the ability to communicate at more than 2.5 bits of information per detec

ed photon at the receiver. Laboratory tests later confirmed these theoretical prediction

However, detection power efficiency was only one of the many factors that needed 

be studied to bring optical communications to reality. Others included laser transmitt

efficiency, spatial beam acquisition, tracking and pointing, link performance tools, flig

terminal systems design, definition of cost-effective ground stations, and mitigation 

Earth’s atmospheric effects on ground stations. 

Several system-level demonstrations were carried out as this work progressed. The fir

carried out in December 1992, involved the detection of a ground-based pulsed las

transmission by the Galileo spacecraft during its second Earth fly-by. The second demo

498

Uplink-Downlink: A History of the Deep Space Networ
stration was carried out over the period November 1995 to May 1996 with the Japane

Earth-orbiting satellite ETS VI.

Both experiments yielded important observational data in support of theoretical studi

and encouraged the further development of optical communications technology wi

supportive flight demonstrations. A selection of technical references related to optic

communications development can be found in section 22 of the appendix at the en

of the book.

DSN Science

Science and technology have always been closely coupled in the DSN. Since the ve

beginnings of the DSN, its radio telescopes had provided world-class instruments f

radio astronomy, planetary radar, and radio science. Many technology program achiev

ments were of direct benefit to these scientific endeavors, and DSN science activiti

frequently resulted in new techniques that eventually found their way into the oper

tional Network.

In the period reported here, the program supported radio astronomy investigations rela

ed to the formation of the stars and to the study of microwave radio emissions fro

Jupiter, as well as radio science measurements of the electron density in the solar pla

ma outside the plane of the ecliptic (Ulysses). It also supported a program of tropospher

delay measurements which would be of direct benefit to the Cassini gravitational wav

experiment. The Goldstone Solar System Radar (GSSR) continued its highly successf

series of Earth Crossing Asteroid (ECA) observations, which began with images of Touta

(asteroid 4179) in 1992 and continued with Geographos (asteroid 1620) in 1994 an

Golevka (asteroid 6489) in 1995. This work was expected to increase in the years ahe

as new and improved optical search programs enabled the discovery of more ECAs. 

selection of technical references related to DSN science can be found in section 23 

the appendix at the end of the book.

49

The Advance of Technology in the Deep Space Network
Chapter 

The Deep Space Network 

as a Scientific Instrument

501
THE TDA SCIENCE OFFICE

In addition to their principal function of tracking and acquiring data from distant spac

craft, the unique capabilities of the Deep Space Network were also used for scientif

research in the fields of radio science, radio astronomy, radar astronomy, crustal dynam

ics, and the Search for Extraterrestrial Intelligence (SETI). With the completion of th

first 64-m antenna at Goldstone in 1966, radio astronomy, which explores the orig

and location of natural sources of radiation in the galaxies, and radar astronomy, whi

investigates the surface and shape of planetary bodies by studying the characteristics 

a reflected radar return, became of much greater significance in the overall function 

the Network.1 Originally, both radio astronomy and radio science were included in th

term “radio science.” As they commanded more attention and more resources from th

DSN, it became necessary to identify and manage them independently of each oth

They are discussed separately in later sections of this chapter. 

From 1967 through 1995, the vigorous efforts of Nicholas A. Renzetti brought th

potential of the DSN as an instrument for scientific research to the attention of the sc

entific community throughout the United States, Germany, France, Italy, Australia, an

Japan. It was his advocacy that led to the negotiation of international cooperative expe

iments in radio science, as well as radio and radar astronomy, and to funding for U.

interagency support agreements for technology development in the fields of crustal dynam

ics and SETI.

While the work in radio science, radio astronomy, and radar astronomy directly involv

the DSN in development, engineering, and the use of the DSN antennas and facilitie

the work in crustal dynamics, except in its very earliest stages, was independent of th

mainstream of DSN activity. Other than its need for observing time on the 70-m ante

nas, the SETI program was also independent of the DSN. It was the strong cross-couplin

between the technologies used by both these latter programs and those of the DSN th

justified their residence at JPL and their association with the DSN. As the followin

paragraphs will show, DSN association with the crustal dynamics and SETI program

was relatively short-lived, while radio science, radio astronomy, and radar astronom

became permanent features of the DSN mission set.

In 1983, Peter T. Lyman, then Director of Telecommunications and Data Acquisition 

JPL, created an office to coordinate and properly manage the several streams of scien

activity with which the DSN was becoming involved. The TDA Science Office wou

guide and coordinate all of JPL’s efforts on behalf of NASA in the fields of radio scienc

502

Uplink-Downlink: A History of the Deep Space Networ
SETI, crustal dynamics, radio astronomy, and planetary radar astronomy (Goldstone Sol

System Radar). Nicholas A. Renzetti was appointed as its first manager.

Nicholas Renzetti had already established a successful career in research and develo

ment when he came to JPL in 1959. Reared in the Bronx, New York, as the son of a

Italian immigrant family with a will to succeed, Renzetti had, by 1940, developed tho

humble beginnings into a Ph.D. from Columbia University, New York. During Wor

War II, Renzetti was engaged in research on countermeasures for acoustic and magne

ic mines for the Navy’s Counter-Mine Warfare Service. In the decade that followe

Renzetti was involved with research on the ballistics of rocket projectiles and develo

ment of test facilities and optical and electronic instrumentation for missiles at the Nav

Ordnance Test Station, China Lake, California. The years 1954 to 1959 saw Renze

working as a physicist, conducting research on the physical and chemical processes 

the Los Angeles atmosphere under the auspices of the Air Pollution Foundation, chair

by President Lee A. Dubridge of Caltech. 

When Eberhardt Rechtin hired Renzetti in 1959 to manage the actual operation of th

new Network, he brought a wealth of in-the-field experience to the position. As ma

ager of the new DSIF Communications and Operations Section in Rechtin

Telecommunications Division, Renzetti’s experience served him well in the years to fo

low, when the Network expanded and the spacecraft it was called upon to suppo

increased in number, complexity, and institutional affiliation.

Stocky in build, Renzetti always dressed in a sport shirt and bolo tie (thin leather co

fastened with a silver or turquoise bolo). He made an exception on formal occasion

when he favored a bright bow tie. A cigar or curved Sherman pipe completed the pi

ture. He was a gruff man, loud of voice, and inclined to shout for emphasis when h

was excited or agitated. Renzetti’s phone conversations or exchanges at staff meetin

were frequently audible to people in nearby offices or corridors. Behind that rather intim

idating exterior lay an extraordinary gentleness that became evident when, on occasio

he invited his engineers to join his family Christmas celebrations.

From the outset, Renzetti determined to leave a written record of the work and accom

plishments of the DSN. He insisted that his people produce publishable accounts of 

of the spaceflight operations in which they were involved, and he saw to it that 

research and development work associated with the DSN, even though it was perform

in areas beyond his responsibility, was likewise properly reported. The formal documen

that he established for publishing these reports were known as the DSN (or later, TDA

50

The Deep Space Network as a Scientific Instrument
Progress Reports. They remain a testament to his success and a permanent record of th

accomplishments of the Network and those associated with it.

Always promoting the potential of the DSN for purposes other than tracking planeta

spacecraft, Renzetti left the area of DSN “operations” in 1983 to head the DSN Scien

Office. There, he led the DSN effort in radio astronomy, radar astronomy, geodynam

ics, and the Search for Extraterrestrial Intelligence. The value of his continuous suppo

for and promotion of the Goldstone Solar System Radar for Planetary Radar Astronom

was recognized by the International Astronomical Union in the naming of Astero

Renzetti in 1997.

He retired from JPL in 1996 and died at his home in San Marino, California, in 199

The combination of sound scientific leadership and NASA’s liberal policy for suppo

of ground-based radio science in the Deep Space Network proved very productive. 

quantitative measure of its productivity is depicted in Figure 8-1, which shows the num

ber of papers published in the scientific literature by investigators using the facilities 

the DSN for radio astronomy, radio science, and radar astronomy for over thirty-fi

years, from 1962 to 1997. 

Note: In the absence of a better estimate, the data shown in Figure 8-1 for Goldston

radar astronomy represents fifty percent of the total number of publications in the l

erature for the years 1962 to 1987.2

At the end of 1995, Renzetti moved to a technical staff position in the TDA directo

office, and management of the TDA Science Office passed to M. J. Klein. By that tim

the scope of the effort in the office had diminished somewhat. Two of the major sc

ence programs described later in this chapter, crustal dynamics and the Search f

Extraterrestrial Intelligence Project (SETI), were no longer under the purview of th

TDA Science Office. The work on crustal dynamics had moved out of JPL to th

National Geodetic Survey, and SETI had been canceled. A third program, radio scienc

became more the province of the flight projects as Galileo arrived at Jupiter and com

menced an intense two-year campaign of Radio Science experiments with multiple Jovia

satellite encounters.

Nevertheless, radio astronomy continued to flourish under the strong scientific leadersh

of Thomas B. Kuiper, while radar astronomy, which had been brought to prominen

in the scientific world by Richard M. Goldstein, expanded the scope of its scientific inve

tigations under the direction of Steven J. Ostro.

504

Uplink-Downlink: A History of the Deep Space Networ
50

The Deep Space Network as a Scientific Instrument

Figure 8-1. DSN science-related publications, 1962–97.

1960 1965 1970 1975 1980 1985 1990 1995 2000

30

25

20

15

10

5

0

Number Published

DSN Radio Science

Publications: 1965–1995

1960 1965 1970 1975 1980 1985 1990 1995 2000

30

25

20

15

10

5

0

Number Published

DSN Radio Astronomy Publications: 1965–1995

1960 1970 1980 1990 2000

18

16

14

12

10

10

8

6

4

2

0

Number Published

DSN Radar Astronomy Publications: 1962–1997
In a major reorganization of the entire TDA organization the following year, the TD

Science Office was incorporated into a new Plans and Commitments Program Office an

its activity was identified collectively as “DSN Science.” Klein remained as manager.

“The DSN is recognized internationally as a world[-]class instrument for radio astro

omy,” said Klein in 1997, “and allows astronomers to take advantage of the very late

technology in Earth[-] and space-based interferometry to produce first[-]rate science. Th

close symbiotic relationship that has developed between technology in the DSN and sc

ence in the DSN serves as a valuable stimulant to the benefit of both. In addition, 

strong constituency for science in the DSN promotes improvements in both technic

and cost performance for the DSN, and it enhances the image of NASA in the inte

national scene by virtue of the significance of its contributions to the sciences of rad

and radar astronomy.”3

506

Uplink-Downlink: A History of the Deep Space Networ
RADIO SCIENCE

By the time the DSIF was established in 1958, radio astronomy had been in existen

as a scientific discipline for many years. Radio astronomers, supported largely by th

NSF, generally directed their attention to extragalactic radio sources, leaving the expl

ration of the bodies and media of the solar system to optical astronomers. 

Thus, the availability of radio-equipped spacecraft traversing the immediate vicinity 

the inner planets encouraged scientists to explore ways in which the downlinks fro

these spacecraft might be used to yield new data about the planets, the Sun, and th

interplanetary medium. Furthermore, this type of science required no additions to th

spacecraft science payload and, for the most part, made use of the signals already ge

erated by the DSN for its own use in spacecraft navigation. The new science becam

known as radio science and was always associated with a particular spacecraft and th

total science inventory of the flight project to which it belonged.4 Radio science inve

tigations for the flight projects formed the major science activity in the DSN for th

first half of the 1960s. Using only the Doppler and range data generated by the trac

ing system, a great deal of significant new planetary science was generated in this perio

In 1981, Renzetti and Allen L. Berman published the first well-documented descriptio

of radio science in the DSN.5 Later, Sami W. Asmar, then manager of radio science 

the Network, expanded this work and brought it up to date through 1993.6

NOTE: The DSN published later versions of the Radio Science System online at http://radi

science.jpl.nasa.gov.

It was Sami Asmar who explained the basic technique of radio science. “By examinin

small changes in the phase and/or amplitude of the radio signal received from a plan

tary spacecraft, radio science investigators are able to study the atmospheric and ionospher

structure of planets and satellites, planetary gravitational fields, shapes and masses, pla

etary rings, ephemerides of planets, solar plasma, magnetic fields, cometary dust, an

several aspects of the theory of general relativity.” 

The early radio science investigators relied on the Doppler and range data generated b

the DSN Tracking system, primarily for spacecraft navigation purposes, to provide th

minute changes in phase and amplitude of the radio signal that were clues to the sc

ence they were seeking from a distant planet or satellite.

50

The Deep Space Network as a Scientific Instrument
Doppler data represents the relative motion (velocity) between the spacecraft and th

Earth station. It is derived from the measured frequency difference between the tran

mitted uplink signal and the received downlink signal. Range data represents the distan

(range) between the spacecraft and the Earth station. It is derived from the measur

time delay between a precision range code transmitted on the uplink and its delay

image received from the spacecraft on the downlink. Special radio transponders carri

on the spacecraft receive the uplink from Earth, add telemetry data, and retransmit th

signal back to Earth without introducing any unwanted changes in the phase chara

teristics of the signal. Such a downlink frequency is said to be “coherent” with the uplin

frequency; therefore, any phase changes observed by the receiving station are attribut

to the “relative velocity” of the spacecraft. 

The spacecraft also carries a very stable radio-frequency oscillator of known frequen

that can be used to supply the downlink frequency when no uplink is present. In th

case, “one-way” Doppler is derived from the measured difference in frequency betwee

the known frequency transmitted by the spacecraft and the actual frequency received b

the Earth station.

Before it can be used by radio scientists or spacecraft navigators, Doppler and range da

must be refined (to remove perturbations introduced by the interplanetary media thoug

which it has traveled) and calibrated (to remove errors introduced by the radio circu

ry in the spacecraft, ground receivers, and transmitters). 

The tracking system is the element of the overall DSN architecture that generates Doppl

and range data from the coherent uplink and downlink between spacecraft and trackin

station. It provides these data, along with appropriate time tags and ancillary data, in 

suitable format for use in spacecraft navigation, orbit determination, and radio science

To generate radio metric data of great precision and stability, the tracking system requir

an ultra-stable clock as a reference, or yardstick, for its uplink and downlink frequen

measurements. In the early years, this was provided by an atomic clock at each Comple

These were rubidium and cesium frequency standards with stability characteristics 

one part in 1012 (rubidium) or one part in 1013 (cesium).

NOTE: To appreciate the significance of these numbers in the time domain, a simple ca

culation will show that one part in ten raised to the thirteenth power (1 x 1013) is approximate

equivalent to three seconds per one million years.

508

Uplink-Downlink: A History of the Deep Space Networ
The rubidium and cesium atomic clocks were eventually superseded by even more st

ble clocks driven by hydrogen masers (1 x 10-14). Equally stringent requirements f

phase and frequency stability applied to the spacecraft radio system where the range an

Doppler “turnaround” functions were performed.

Radio metric data generated by the tracking system was used for many applications 

radio science. Doppler data from spacecraft on planetary flyby or orbiting missions pr

vided information regarding the orbit, mass, gravitational, and physical properties of th

planetary bodies for celestial mechanics investigations. It also provided planetary atmo

pheric information as the downlink signal was refracted through planetary neutr

atmospheres. When dual-frequency downlinks (S-band and X-band) became availab

(first on Mariner 10 (Venus/Mercury) in 1973), it enabled measurements of column

electron density changes in the solar wind and planetary ionospheres.

Range data was used to measure planetary distances, as well as the signal time delay d

to the solar wind (electron density) and gravitational (relativistic) bending near the Su

In 1976, the various components (such as open-loop receivers, stable oscillators, an

recorders) that had been used for the previous decade or so to make radio science obse

vations were incorporated into a new DSN system designed to handle the unique nee

of radio science for all flight projects. Known as the Radio Science System, it genera

ed radio science data as a data product for delivery to the Flight Project Science Tea

in the same way as telemetry or radio metric data was considered to be a “deliverable

Together with the tracking system and ancillary calibration data, the Radio Science Syste

generated all of the DSN radio science data for the planetary missions after this tim

As described by Berman, the essential feature of the new DSN Radio Science Syste

was its ability to reduce the amount of radio science data to be recorded (digitally) f

each occultation by a factor of 10 to 100, compared to the fixed tuned analog recor

ing technique previously employed by the Network. This was accomplished b

automatically tuning the open-loop receivers in conformance with a predicted Doppl

frequency profile based on precise knowledge of the planet and spacecraft orbits, alon

with a model of the planetary atmosphere. Depending on the accuracy of the “predict

and the nature of the data itself, the output of the open-loop receiver would then becom

a new “baseband” frequency lying within a few kHz of the predicted frequency an

could easily be digitized and written on computer-compatible tape at the observing st

tion. In addition to the “baseband” frequency, the digital recording contained a copy 

the frequency profile used to generate the “baseband” data with appropriate timing info

mation. This information was then shipped to the experimenter, transmitted to JPL v

50

The Deep Space Network as a Scientific Instrument
the GCF, or both. By combining the “predict” frequency with the “baseband” freque

cy, the experimenter could recover the actual received frequency. The new system al

provided real-time spectral data for display on Signal Spectrum Indicators (SSIs) at th

tracking station and in the Radio Science Team area at JPL. The SSIs were used f

monitoring performance, calibration, and analysis purposes, as well as for quick-look sc

ence evaluation.

The new capability, referred to as “real-time bandwidth reduction,” was delivered to th

Network for first operational use with the Pioneer Venus mission in December 197

The Occultation Data Assembly, a part of the Radio Science Subsystem in which th

bandwidth reduction function described above was performed, is illustrated in function

form in Figure 8-2.

As an integral part of the DSN, the Radio Science System was upgraded from time 

time to reflect the introduction of new technology, processes, and capability in the ove

all DSN. In 1996, the Radio Science System acquired a capability that allowed the Rad

510

Uplink-Downlink: A History of the Deep Space Networ

Figure 8-2. Real-time bandwidth reduction in the radio science Occultation Data Assemb

S-BAND

OPEN-LOOP

RECEIVER

PROGRAMMED

OSCILLATOR

X-BAND

OPEN-LOOP

RECEIVER

SPECTRAL

SIGNAL

INDICATOR

PROGRAMMED

OSCILLATOR

CONTROL

ASSEMBLY

RECEIVER-EXCITER

SUBSYSTEM OCCULTATION DATA ASSEMBLY

A-D

CONVERTER

OCCULTATION

CONVERTER

SUBASSEMBLY

A-D

CONVERTER

D-A

CONVERTER

FREQUENCY

MONITOR

SUBASSEMBLY

MODCOMP

11/25 COMPUTER

COMP TAPE

TERMINET

I/0

DISK

FREQ. PREDICTS

RAD SCI DATA WBDL

HSDL

OPEN LOOP STATUS WBDL

SPECTRA

NOCC RADIO SCIENCE

SUBSYSTEM

NOCC SUPPORT

SUBSYSTEM

PREDIK

DSS

MONITOR AND

CONTROL

SUBSYSTEM

RADIO SCIENCE

EXPERIMENTOR

GCF

DATA RECORDS

SUBSYSTEM

* SHIPPED

RADIO SCIENCE

EXPERIMENTOR
Science Team at JPL to share control of the Radio Science System at the Complex

with the station operators. This placed the burden of operating the complicated Rad

Science System back on the user group and reduced the responsibility and workload 

the DSN tracking stations. At last, the Radio Science Teams would have the same fle

ibility and control of their instrument as the other science experiment teams enjoy

with instruments carried by the spacecraft. Remote control for radio science was fir

used for Galileo orbital operations in late 1996 and, after some initial integration pro

lems, proved to be of great value to both the investigators and the DSN in dealing wi

the heavy load of radio science through the end of the Galileo Mission. 

Celestial Mechanics

Renzetti and Berman suggested that the DSN (then DSIF) radio metric capabiliti

should be first used for radio science purposes by Anderson and Warner for celest

mechanics experiments with the 1962 Mariner 2 mission to Venus. Using only th

Doppler navigational data from this flight, the experimenters were able to make orde

of-magnitude improvements in the determination of the masses of the Moon and Venu

All through the Mariner Era, the Mariner 4 (Mars), Mariner 5 (Venus), and Mariner 

(Mars) missions were used for celestial mechanics experiments to determine the mass

of Venus and Mars.

Doppler measurements from the Lunar Orbiter and Apollo missions led to the discove

of mass concentrations (mascons) on the Moon, and analysis of the Mariner 10 Doppl

data in 1973 and 1974 enabled the determination of the mass and shape of Mercury.

In the Voyager Era, celestial mechanics investigators used the DSN radio science da

from the Pioneer and Voyager missions to Jupiter and Saturn to produce a wealth 

new knowledge on the physical properties of those planets and their satellites.

Venus had received intense study by celestial mechanics investigators since the time 

the Mariners. Data from long-term orbiting spacecraft, most notably Pioneer Venus Orbit

and Magellan Radar Mapper, produced a data volume equivalent to thousands of sing

flybys, making the gravity-field of Venus almost as well understood as that of Earth.

Celestial mechanics studies of Mars also had the benefit of orbiting spacecraft, startin

with Mariner 9 in 1971 and the two Vikings in 1976. These studies would have bee

extended with Mars Observer in 1993 had the spacecraft not been lost just prior 

entering Mars orbit. They were, however, resumed with the Mars Global Surveyor m

sion in 1997.

51

The Deep Space Network as a Scientific Instrument
Prior to the Galileo mission to Jupiter in 1995, knowledge of the gravity fields of Jupit

and its satellites was based on the combined results of celestial mechanics experimen

conducted during the flybys of Pioneers 10 and 11 and Voyagers 1 and 2. This had pr

vided a good estimate of the Jupiter mass but contributed little to existing knowled

of the satellites. Although the Galileo orbits of Jupiter were too high to contribute mu

to gravity field measurements of the planet itself, the close Encounters of Io, Ganymed

Callisto, and Europa provided an immense amount of data for analyses of the intern

structure of these Jovian satellites.

During the period July 1996 to December 1997, investigators carried out twenty-thr

celestial mechanics experiments while the Galileo spacecraft was in orbit around Jupit

The purpose of this campaign was to refine the knowledge of the position of Jupiter 

the plane of the sky which, in turn, led to a significant improvement in knowledge 

the ephemeris of Jupiter. To obtain the increased accuracy required for these observ

tions, the DSN generated ranging data from several stations simultaneously during th

spacecraft overlap view period between Complexes, with the spacecraft in the “one-wa

mode. Reduction of these data to extract the simultaneous spacecraft-to-station, pat

length differences from the known station locations yielded data from which a ve

precise determination of the spacecraft orbit could be made. Investigators were then ab

to refine their knowledge of the position of Jupiter from its effect on the very precis

ly known orbit of the spacecraft. The range differencing technique used in these experimen

was known as Delta Differenced One-way Ranging (Delta DOR).

The Voyager 1, Voyager 2, and Pioneer 11 Encounters of Saturn contributed radio sc

ence data for celestial mechanics estimates of the masses and gravity fields of Saturn an

its satellites Rhea, Titan, Tethys, and Iapetus. A previously unknown moon, S13, w

first discovered by its gravitational perturbations of the Doppler data from the Voyag

2 Saturn Encounter. Its presence was later verified by optical imaging from the spac

craft. 

Further celestial mechanics investigation of Saturn must await the arrival of Cassini wi

the Huygens Titan Probe in 2004. Then radio science data at X-band and Ka-ban

from multiple Cassini orbits through the Saturnian system will provide investigators wi

additional information on masses, densities, and interactions between the planet and 

satellite Titan.

Celestial mechanics information on Uranus was derived from the radio science data take

during the Voyager 2 Encounter of the planet in 1986. Combined with imaging data 

512

Uplink-Downlink: A History of the Deep Space Networ
the satellites, the Doppler perturbations enabled great improvement in determination 

the masses of five of the major satellites and of the planet itself. 

The two-way Doppler data obtained by the DSN Radio Science System during th

Voyager 2 Close Encounter of Neptune in 1989 provided celestial mechanics investig

tors with basic data from which the masses of Neptune and its satellite Triton could 

estimated to an accuracy of 0.0003 percent and 0.3 percent respectively. 

Solar Corona and Solar Wind

In 1965, as the Mariner 4 (Mars) spacecraft passed within 0.6 degrees of the solar dis

Richard M. Goldstein used the not-yet-fully-operational 64-m antenna (DSS 14) 

Goldstone with an “open-loop” receiver to observe the spectral spreading of the spac

craft signal as it passed through the solar corona. This marked the first use of the DS

for Solar Corona research. Berman, and later Woo, were able to interpret the observ

results in terms of the relationship between spectral broadening and integrated coron

electron density. Subsequently, similar experiments with the Helios and Pioneer spac

craft would confirm and expand the original measurements and the underlying theorie

In addition to spectral broadening, the radio signal from a planetary spacecraft expe

ences a second effect as it passes through the Solar Corona. The RF signal experienc

a small, but measurable, rotation of its plane of polarization. Known as “Faraday Rotation

this effect was linked to both electron density and the solar magnetic field in an expe

iment carried out at DSS 14 by Charles T. Stelzried in 1968.7 To support this experimen

DSS 14 had been equipped with a rotatable, linear microwave feed system driven by 

closed-loop polarimeter that would automatically track the orientation of the polariz

tion of the received signal. Using the linearly polarized signal from the Pioneer 6 spacecra

as it was occulted by the Sun in November 1968, these observations yielded valuab

information on both transient and steady-state effects in the solar corona.

Similar experiments were carried out at the other 64-m stations with Helios and Pione

spacecraft in 1975 and 1977. An ambitious Faraday Rotation experiment, planned f

the Galileo mission to Jupiter in 1995, was eliminated in 1991 when the failure of th

Galileo high-gain antenna limited the downlink to S-band right circular polarization on

However, successful Faraday Rotation experiments using the Magellan spacecraft at Ven

were carried out by Asmar and Bird in 1991 at both S-band and X-band. 

Range data generated by the DSN tracking system also provided a powerful tool f

determination of electron density in the solar corona, provided that all other sources 

51

The Deep Space Network as a Scientific Instrument
error could be properly accounted for. Duane O. Muhleman, John D. Anderson, an

others first used this method during the solar conjunctions of Mariners 6 and 7 in 197

using ranging data acquired at DSS 14.

During the 1975 solar conjunctions of Pioneer 10, Pioneer 11, and Helios 1, Allen 

Berman and Joseph A. Wackley of JPL, working in collaboration with Jose M. Ure

at the Madrid Complex, were able to demonstrate that the fluctuations observed in th

Doppler signature of a single S-band downlink provided an excellent measure of tu

bulence in the solar wind. Since Doppler fluctuations (or “noise”) were automatical

computed for monitoring the performance of the DSN tracking system, it represent

a “free” source of scientific data and was compared favorably with the more accura

dual-frequency methods. Electron density measurements based on dual-frequency S- an

X-band Doppler were not degraded with many of the sources of error present in si

gle-frequency measurements. Measurements with dual-frequency Doppler downlinks o

the Mariner 10 spacecraft in 1974 and dual-frequency ranging on the Viking spacecra

in 1977 and 1979 yielded excellent results. 

Observations of Doppler scintillation from Pioneer Venus were compared with ind

pendent observations of solar plasma transients from Helios 1 by Woo and Schwen 

1991. They showed that several Doppler transients, observed by Pioneer Venus at 15 

18 solar radii, were observed about 48 hours later as solar plasma shocks by Helios 1 

170 to 174 solar radii.8

Solar wind scintillation experiments played a large part in the Galileo radio science pr

gram. The experiments were designed to gather data for the study of the solar win

within 0.3 AU of the Sun. The scintillation experiments were originally intended 

complement solar corona experiments but were eliminated by the loss of the HGA an

the dual-frequency downlinks. Five experiments were conducted successfully, on S-ban

only, during superior conjunctions between December 1991 and February 1997. 

Radio Propagation and Occultation 

Almost every planetary mission, past and future, is concerned with the investigation 

planetary atmospheres, ionospheres, rings, and magnetic fields. Such investigations a

based on the perturbation of the phase and amplitude of the spacecraft downlink b

the extended atmosphere of the planet as the radio signal passes through it during pe

ods of occultation. These perturbations are contained in the data captured by the open-loo

receivers of the Radio Science System and can be converted into a refractivity prof

for the planetary atmosphere after the data are corrected for the contribution due to th

514

Uplink-Downlink: A History of the Deep Space Networ
geometrical flight path of the spacecraft. Information regarding electron distribution 

the ionosphere, the temperature-pressure profile in the neutral atmosphere, or partic

size distribution in the ring material can be derived from the refractivity profile.

According to Asmar and Renzetti, the method was first proposed by V. R. Eshelman 

1962. Independently, D. L. Cain, leading a JPL team engaged in analyzing the effe

of refraction in Earth’s atmosphere on the accuracy of Doppler data, recognized the po

sibility of applying the sensitivity of Doppler phase measurements to the study 

atmospheres and ionospheres of other planets. The theoretical analysis was developed b

G. Fjelbo in 1964.

The occultation experiments required special receivers to extract the Doppler data in add

tion to the normal DSN receivers. The normal receivers in the DSN tracking syste

were of the “closed-loop” type; that is, they employed a “phase-locked tracking loop” 

keep them tuned to the frequency of the downlink carrier signal. As the frequency of th

downlink changed as a result of the Doppler effect of the spacecraft’s motion relative 

Earth, the “phase-lock loop” caused the receiver to follow the changes and thereby “mai

tain lock.” Doppler data was generated by comparing the received downlink frequen

with the uplink transmitter frequency (two-way), or a precise estimate of the frequen

of the Ultra Stable Oscillator (USO) carried by the spacecraft (one-way).

When a spacecraft entered occultation by a planet, the downlink signal was cut o

and the receivers dropped lock. When the spacecraft exited occultation and the si

nal reappeared, valuable time was lost while the receivers reacquired the downlin

Thus, the important radio science data was only available for a short period imm

diately before entry and immediately after exit as the signal transited the thin planeta

atmosphere. Therefore, in 1964, special wide-bandwidth “open-loop” receivers we

added to the DSN tracking system to ensure that the downlink would appear in th

“open-loop” receiver passband the instant it emerged from occultation. The “ope

loop” receivers were tuned by a programmable local oscillator, which was driven b

a computer program based on the spacecraft orbit and other pertinent parameter

The open-loop output was recorded on analog magnetic tape recorders at the statio

and subsequently shipped to JPL. There it was digitized and delivered to the expe

imenters for analysis.

Occultation experiments using open-loop receivers in the DSN were made for the fir

time in 1965, when Mariner 4 flew by Mars. These experiments were highly succes

ful; they showed that the Martian atmosphere was predominantly carbon dioxide an

that the surface pressure was less than one percent of that of Earth, an order of ma

51

The Deep Space Network as a Scientific Instrument
nitude less than had previously been thought.9 Measurements of the electron density 

the Martian ionosphere were also obtained. During the late 1960s and early 1970

occultation experiments were carried out by the Mariner and Viking missions to th

inner planets (Mercury, Venus, and Mars).

The Voyager Era was prolific in producing occultation radio science for the outer pla

ets. This began in 1973 with the Pioneer 10 flyby of Jupiter, repeated a year later b

Pioneer 11. Pioneer 11 went on to make the first occultation measurements of th

atmosphere and ionosphere of Saturn in 1979. Occultation experiments were conduct

with Voyagers 1 and 2 at Jupiter in 1979 and at Saturn in 1980 and 1981, with Voyag

2 at Uranus in 1986 and at Neptune in 1989. These experiments determined atmo

pheric pressure levels, temperatures, and constituents, as well as the characteriz

ionospheres of Jupiter, Saturn, and Triton.10 The theory of radio occultation techniqu

was extended in 1980 to include ring occultation experiments during the Voyager 

Encounter of Saturn. 

Ulysses experimenters used occultation radio science during their spacecraft gravity ass

flyby of Jupiter in February 1992 to derive the columnar electron density of the Io pla

ma torus. This experiment was enhanced by the presence of a dual-frequency (S- an

X-band) downlink from the spacecraft.

In 1991 and 1992, Magellan experimenters obtained highly accurate profiles of atmo

pheric refractivity and absorptivity of Venus using occultation radio science. These profil

were used to deduce ionospheric density, atmospheric temperature, pressure, and sulf

ric-acid abundance on Venus. The dual frequency, combined with the higher power 

the Magellan downlinks, enhanced the end result by eliminating errors and making 

possible to penetrate the atmosphere to greater depth than would otherwise have bee

possible.

The orbital part of the Galileo mission to Jupiter provided many opportunities for occu

tation radio science. In 1996 and 1997, twenty-two occultations were observed. The

included a single occultation by Callisto and multiple occultations by Jupiter, Io, Ganymed

and Europa. The information derived from these data substantially increased the exis

ing body of knowledge about the ionospheric characteristics of all of those bodies. 

The Cassini mission to Saturn in 2004 will include several occultation flybys of Satu

and Titan, which will be observed with S-band, X-band, and Ka-band downlinks. Da

obtained from observations in each of these bands has advantages in the study of d

516

Uplink-Downlink: A History of the Deep Space Networ
persive media like the atmospheres of Saturn and Titan and also makes it possible 

determine the particle size distribution in Saturn ring structure. 

Relativistic Time Delay

Depending on the Earth-Sun-spacecraft geometry, range measurements from Earth to 

planetary spacecraft passing through solar conjunction can enable a test of a portion 

the General Theory of Relativity. Einstein’s theory predicts that electromagnetic wav

passing close to massive bodies, such as the Sun, are influenced by the Sun’s gravit

tional field in such a way that the signal path between spacecraft and Earth is “ben

by the intense gravitational force of the Sun. The effect of the “bending” is to intr

duce a time delay along the signal path between spacecraft and Earth. This time del

can be measured by the DSN tracking system. Using the measured signal time del

and knowledge of the Earth-Sun-spacecraft geometry at the time the measurement w

taken, radio scientists are able determine a value for a key parameter in the mathema

ical equations by which the theory is described. This parameter, known as th

“Schwartzchild metric,” is denoted by the Greek symbol gamma. In the theory, the val

of gamma is 1.0. For a relativistic experiment, therefore, the closer the results approa

a value of 1.0 the better its agreement with theory.

To measure signal time delay, the DSN used the ranging system which forms a part 

the DSN tracking system described earlier.

The first major attempt to measure the relativistic bending of a spacecraft signal w

made by John D. Anderson and others during the solar conjunction of Mariners 6 an

7 in the mid-1970s.11 The results obtained from this experiment verified the value 

gamma to about 6 percent, i.e., gamma = 1.00 ± 0.06. The major sources of error we

attributed to uncertainty in the accuracy of the spacecraft orbit and in the measureme

of time delay due to scattering effects of free electrons in the solar corona. In time, the

errors were reduced, and a later experiment with Mariner 9 brought the uncertainty 

the value of gamma down to 2 percent.

A very significant improvement in accuracy resulted from the relativistic experimen

carried out in 1976 and 1977 by Shapiro, Cain, Reasonberg, and others with the Vikin

Mars Orbiter and Lander spacecraft. Benefiting from significant improvements in th

calibrations of the tracking system, the use of dual-frequency downlinks, and preci

knowledge of the position of the landed spacecraft, independent experimenters at MI

and JPL determined the value for gamma of 1.00 ± 0.002 the most accurate test of th

theory to that time. Repeating the experiment again during the Voyager 2 solar co

51

The Deep Space Network as a Scientific Instrument
junction in December 1985, Anderson and others obtained a value of 1.00 ± 0.03 f

gamma.

Improved accuracy is expected from two relativistic experiments to be conducted du

ing the solar conjunction periods of the Cassini mission to Saturn in 2003 and 200

The greater accuracy will derive from the use of Ka-band, which, with its waveleng

of less than one centimeter, is less affected by interplanetary media than the longer wav

length signals used previously.

Gravitational Waves

The General Theory of Relativity predicted that the violent collapse of stellar bodi

into supermassive black holes would generate gravitational waves in the form of spat

strains propagating through the solar system at the speed of light. These waves we

expected to slightly alter the distance between two separated free masses, which wou

be detectable as a proportionate fractional-frequency shift in ultra-precise Doppler da

from a space-based detector using Earth and a planetary spacecraft as free test masse

Because gravitational waves are very weak and propagate at very low frequencies, spac

based systems offered the best chance for their detection.

The use of ultra-precise two-way Doppler from a distant spacecraft (greater than 1 AU

to detect very-low-frequency gravitational waves was proposed by Estabrook and Wahlqu

in 1975.12 Driven by an ultra-stable frequency standard, the DSN tracking system ge

erates precision two-way Doppler from a comparison of the uplink and coherent downlin

frequencies from the spacecraft and, in doing so, continuously measures the fraction

frequency shift due to relative Earth-spacecraft motion. A gravitational wave passin

through the system causes a unique “three-pulse” signature to appear in the Doppl

data due to a combination of buffeting effects on the Earth and the spacecraft an

speed-up of the tracking station clocks (frequency and timing systems). The characte

istics of the “three-pulse” signature depend on the relative positions of Earth and th

spacecraft and the direction of the gravitational wave. These effects are illustrated ve

simply in Figure 8-3.

Experiments conducted through 1990 using Viking, Voyager, and Pioneer spacecraft fail

to detect the existence of gravitational waves. However, the sensitivity of these tests w

limited by noise due to plasma propagation. 

The advent of hydrogen masers as frequency standards for the DSN and the additio

of X-band uplinks to the existing S- and X-band downlinks improved the sensitivity 

518

Uplink-Downlink: A History of the Deep Space Networ
the tracking system for detection of the gravity waves by a factor of about 10. With th

launch of Galileo in 1989, carrying X-band uplink in addition to the standard S-ban

uplink and S- and X-band downlinks, expectations were high for the detection of gra

ity waves in the Galileo Era. A particularly interesting coincidence experiment involvin

Mars Observer, Galileo, and Ulysses was planned for early 1993. The sensitivity of th

tracking system had been set at 5 x 10-15 as offering the best chance for successful dete

tion of the elusive gravitational waves. This experiment afforded several uniq

opportunities for immediate confirmation of the detection of a gravity wave and dete

mination of the direction of the incident wave from the Doppler signatures of the thr

spacecraft. The joint experiment ran for three weeks in the spring of 1993. Two furth

searches for gravitational waves with the Galileo spacecraft were planned for May 199

and June 1995 during the solar opposition periods.

Unfortunately, the loss of the X-band uplink and downlink, as a consequence of the fa

ure of the Galileo High Gain antenna in April 1991, reduced the sensitivity of the rad

science system for gravity wave detection to that of the residual S-band mission, deem

marginal at best. None of the experiments succeeded in detecting the presence of gra

itational waves; nevertheless, interest in pursuing the search for gravity waves persiste

The launch of Cassini in 1997, with Ka-band and X-band uplinks and downlinks, 

51

The Deep Space Network as a Scientific Instrument

Figure 8-3. Characteristic three-pulse signature of a gravitational wave in two-way Dopp

data.

Gravitational 

Wave Spacecraft

L

Z

Z

θ

Earth buffeting Spacecraft

buffeting

(1 + cos θ) L/c

∆ ν

Earth

2 L/c

Earth buffeting,

transponded

TIME

ν
well as more stable ground and spacecraft elements in the tracking system, offered th

hope of observations at a much higher sensitivity level. It was estimated that the sen

tivity could be as high as 10-16 for about one month of tracking near each of three sol

oppositions in 2001, 2002, and 2004, provided that tropospheric effects could be su

ficiently removed with water vapor radiometer techniques.

Looking to the future for gravitational wave searches, S. W. Asmar believed that se

sitivity improvements beyond this level would require moving the tracking statio

itself into Earth orbit so that both test masses would be in space, unperturbed b

the many unmodeled geophysical effects that are associated with an Earth-based st

tion. In fact, this concept is to be employed in future spaceborne, laser-base

gravitational wave experiments. 

520

Uplink-Downlink: A History of the Deep Space Networ
RADIO ASTRONOMY

The origins of the DSN owe much to the science of radio astronomy. By the time 

its establishment in 1958, radio astronomy had been in existence as a scientific disc

pline for many years. As discussed in the early chapters of this book, the origin

26-m-diameter antennas of the DSIF were adaptations of existing, commercially ava

able radio astronomy dishes and mounts. The original 64-m-diameter antenna built 

Goldstone in 1966 was based on the design of a radio telescope of similar size opera

ed by the Australian Scientific and Industrial Research Organisation at Parkes, Austral

It came as no surprise when the radio astronomy community showed early interest 

the substantial new global facility then being implemented by NASA for exploration 

the solar system by means of planetary spacecraft. However, the National Scien

Foundation, which was the principal sponsor of radio astronomy research in the Unit

States, tended to promote research in regions of the cosmos beyond the solar system. 

was more interested in sponsoring studies associated with astrophysics, the galaxies, an

stars than those related to furthering the existing knowledge base of the solar system

Thus, the early capabilities of the DSN, designed for in situ observations of the inn

solar system with planetary spacecraft, offered little of interest to radio astronomers depen

ent on the NSF for their sponsorship. 

In 1966, the first of the DSN 64-m antennas was put into operation at Goldston

With that event, radio astronomy, as a scientific endeavor distinct from that associat

with planetary spacecraft, became a new capability for the DSN. The new antenna, ov

six times more sensitive than the existing 26-m antennas, more than doubled the ran

of the Network and, in doing so, provided the best instrument available for radio astro

omy at that time. With such an instrument, radio astronomers could now direct the

research to regions beyond the solar system with a capability that was comparable t

and in many ways better than, that of the other large radio telescopes throughout th

world. Prompted by a strong advocacy from Nicholas A. Renzetti, who was managin

tracking operations for the DSN at that time, the NASA Office of Tracking and Da

Acquisition (OTDA) approved the allocation of a limited amount of time on the ne

antenna for radio science observations on a noninterference basis with the antenn

prime task of tracking planetary spacecraft. Official notice of the availability of the ne

facility brought an immediate response from the radio astronomy community.

In 1967, the DSN was approached by David S. Robertson of the Australian Space Resear

Group with the first proposal for a long baseline interferometry measurement of extr

galactic radio sources. This was to be done using the baseline between Goldstone an

52

The Deep Space Network as a Scientific Instrument
DSN antennas at Woomera and Tidbinbilla in Australia, which would make a resolvin

power of 2 x 10-3 arc-second possible. With Allen T. Moffet as a coexperimenter, the fir

observations were made in 1967 and continued at intervals for several years thereafter

In 1968 and 1969, DSS 14 was used extensively by Moffet of Caltech and Ekers an

Downs of JPL to study pulsar emissions. By 1969, the volume of requests for observin

time on the antenna had increased to the point where it became necessary to evaluate an

select the most appropriate and worthy non-NASA proposals to compete for the limit

amount of available antenna time. A Radio Astronomy Experiment Selection Panel (RAES

composed of distinguished radio astronomers nationwide, was established for this purpos

and a DSN radio astronomy support group was created to facilitate the technical and log

tical interfaces between the astronomers and the operational DSN. These organizations we

announced to the radio science community in the technical literature at the end of 196

The next two years saw a substantial increase in the demand for radio astronomy tim

at DSS 14 and DSS 13 as pulsars, very long baseline interferometry, Jupiter radio em

sions, brightness, temperature, and rotation period continued to attract the attention 

radio astronomers.14

Management policy for support of “Ground-Based Radio Science” in the Deep Spa

Network was formalized by NASA in 1971 with an appropriate NASA Manageme

Instruction setting forth the requirements for submission of requests for experiment su

port and the levels of approval required. A level of support was determined in terms 

percentage of available antenna time and assigned to the RAES panel, and its subs

quent equivalent for distribution amongst approved experimenters. To distingui

between the radio experiments involving spacecraft and those involving celestial bodie

NASA adopted the following definitions.

“Radio science” would refer to the acquisition and extraction of information from spac

craft-originated signals that had been affected by celestial bodies or the propagatio

media. “Radio astronomy” would refer to the acquisition and extraction of informatio

from signals that had been emitted by or reflected from natural (non-spacecraft) source

In the past, all experiments had been loosely referred to as “radio science,” but fro

this point forward, the DSN would observe these new conventions in its manageme

and support for radio science and radio astronomy. Although at that time the impo

tant planetary radar observations being made at Goldstone came within the definitio

of radio astronomy, it would later evolve into a separate activity as the Goldstone Sol

System Radar (GSSR).

522

Uplink-Downlink: A History of the Deep Space Networ
For the next decade and a half, radio astronomy continued to play an important role in t

total sum of DSN activity. As the DSN capability increased with the construction of 64-

antennas in Australia and Spain, and later with their enlargement to 70-m diameter, so d

the capability for radio astronomy, and the scientists were quick to use them to advantag

The level of radio astronomy activity in the DSN over the period 1971 through 198

is summarized below:

Radio Astronomy in the Deep Space Network: 1967–87*

1967–71

Various Sponsors, NSF, CIT, JPL, Australia

Twenty experiments, various subjects

1972–87

RAES-Sponsored Research

Sixty discrete experiments in various subjects

NASA-Sponsored Research

Five continuous experiments in the following:

Interstellar microwave spectroscopy

Planetary radio astronomy

Hipparcos VLBI

Quasar and galactic nuclei VLBI

Southern Sky Survey with Tidbinbilla Interferometer

*The details of this work were collected and published by Renzetti and others in 1988.

International Cooperation

While individual radio astronomers in the United States continued to carry out the

work through the scheduling and interface organization in the DSN Operations Offi

at JPL, associations of a more international nature were also formed during this perio

In 1983, the Goldstone 70-m antenna cooperated with the National Radio Astronom

Observatory 43-m antenna and the 22-m antenna of the Center for Astrophysics in th

Crimea, USSR, in an interferometric network to study extragalactic sources at a wav

length of 3 cm with high resolution. Thus was forged the DSN’s first close cooperati

association with radio astronomers from NRAO, Cornell, Caltech, and the Soviet Unio

This association would continue to be productive in the field of radio astronomy resear

in the years that followed.

52

The Deep Space Network as a Scientific Instrument
Tidbinbilla Interferometer

In 1972, Samuel Gulkis of JPL, in association with David L. Jauncey and Michael 

Yerbury, then of Cornell University, put forward a proposal that would use the two exis

ing DSN antennas at the Canberra Deep Space Communication Complex in Australia 

create a high-sensitivity, phase-stable interferometer that could be operated in near-re

time. The two antennas (26 m and 64 m in 1972, later enlarged to 34 m and 70 m

were separated by 195 meters on a north-south baseline and, together with available low

noise maser amplifiers and a common operating frequency at 2.3 GHz, provided a uniq

opportunity to implement a high-sensitivity interferometer with a positional capability 

approximately 2.0 arc-seconds at minimal cost. It would be the only instrument in th

Southern Hemisphere capable of carrying out rapid measurements of weak radio sour

positions with arc-second accuracy and flux densities to the millijansky level. These da

would be used for unambiguous identification of radio sources with cataloged infrared an

optical celestial objects. Earlier, whole (southern) sky surveys made with the Parkes Rad

Telescope at 2.7 GHz had listed over 12,000 radio sources, but these data did not ha

sufficient positional accuracy to permit confident identification with visible objects and le

unanswered many questions of interest to radio astronomers. The proposed interferom

ter would be used to supplement these data and provide a complete southern sky surve

The Tidbinbilla two-element interferometer was constructed and tested in the years 197

to 1979 and began radio astronomy observations at 2.3 GHz in 1980.15 It was upgra

ed to operate simultaneously at 2.3 GHz and 8.4 GHz in 1986.

By 1988, over 1,500 of the radio sources listed in the Parkes survey had been measure

and many had been identified optically. A great deal of attention was paid to the stud

of quasars. The identification in 1982 by Jauncey and others of the most distant quas

discovered to that time was attributed solely to the accuracy of the Tidbinbilla interfe

ometer.16 A sensitive search of the brighter stars in the Southern Hemisphere for possib

radio emissions was initiated in 1986, depending on the narrowness of the interferomet

beam to reduce confusion with the background galactic sources of radiation. Data li

these would be used by the Space Telescope and other astronomical spacecraft (Hipparchu

as well as for navigation of conventional spacecraft and station location purposes.

The Tidbinbilla interferometer continued to operate as a significant capability for rad

astronomy in Australia under the Host Country program described below.

524

Uplink-Downlink: A History of the Deep Space Networ
Orbiting VLBI

The feasibility of using a spacecraft in Earth orbit as one element of a very long bas

line interferometer for radio astronomy observations was demonstrated by Gerry Le

and his team in 1983.17 Building on these ideas, James Ulvestad, Roger Linfield, an

Chad Edwards applied these principles to make successful observations of Extra Galact

Radio Sources (EGRSs) in August 1986. The enormous increase in baseline length (se

eral Earth diameters) thus obtained would provide a proportionate increase in resolvin

power, greatly exceeding that of an interferometer constrained by Earth-based antenna

The experiment was conducted at a frequency of 2.3 GHz using the 4.9-m antenna 

the geosynchronous NASA Tracking and Data Relay Satellite System (TDRSS) as th

space-borne element. The DSN 64-m antenna at Canberra, Australia, and the ISAS 6

m antenna at Usuda, Japan, formed Earth-based elements. In January 1987, 23 EGR

were detected on a baseline as long as 2.15 Earth diameters.

These successful experiments demonstrated that a ground-based frequency reference cou

be accurately transferred to an orbiting spacecraft and that observations of radio sourc

acquired by an orbiting spacecraft could be transmitted and recorded on Earth with th

necessary precision to achieve correlation with similar data from Earth-based antennas. T

success of these early experiments had positive implications for the future of orbiting VLB

Within the next ten years, the DSN would become a participant in the Space VLB

cooperative program involving NASA (U.S.A.), ISAS (Japan), and ASC (Russia). Th

first of two space VLBI missions, VSOP (HALCA), would be launched in 1997 and 

special subnetwork of 11-m tracking antennas, operating at Ka-band, would be add

to the Network. The DSN 70-m antennas would also participate as co-observers in th

Space VLBI project with many other radio astronomy observatories around the worl

Host Country Programs

The original intergovernmental treaties that were executed between the United State

Spain, and Australia for the implementation and operation of Deep Space Communicatio

Complexes in those countries made explicit provision for the conduct of independe

radio astronomy research on these facilities by Host Country agencies on a noninte

ference basis with the prime NASA business of spacecraft tracking. In the DSN resour

planning process, “Host Country” programs were allotted a specified amount of ante

na time on an annual basis, and it was left to the local complex directors to assign th

time to the individual investigators as appropriate. 

52

The Deep Space Network as a Scientific Instrument
In Spain, the prime cooperating agencies were the Instituto Geografico National and th

Instituto Nacional Tecnica Aeroespacial, while in Australia, the prime cooperating agen

was the Commonwealth Scientific and Industrial Research Organisation (CSIRO). 

both countries, the DSN antennas participated in interferometric geodetic surveys of th

continents and observation of pulsars under the Host Country program. In 1992, th

Tidbinbilla interferometer was brought into the Host Country program and continu

to share antenna time with other Australian radio astronomy investigations at the CDSCC

Cross-Support Agreements

The important role played by the Parkes Radio Astronomy antenna in supporting th

Voyager Neptune Encounter as an element in the Parkes Canberra Telemetry Arr

(PCTA) was discussed in an earlier chapter. The NASA/CSIRO negotiations for th

support in September 1986 resulted in a Memorandum of Understanding. This doc

ment provided time on the DSN 70-m antenna for the use of CSIRO radio astronome

on a quid pro quo basis for the time provided by Parkes for the Voyager Encount

This “cross-support” agreement was a productive source of radio astronomy scienc

although the over-subscription of the DSS 43 antenna for spacecraft support in lat

years made it difficult for the DSN to meet the original expectations for “payback.” 

Guest Observer Program

Under the Guest Observer Program, DSN facilities were made available to non-JPL sc

entists for radio astronomy research, subject to peer review and approval of their proposa

by the U.S. National Radio Astronomy Observatory (NRAO). The purpose of the revie

was to establish the scientific merit of the proposal and verify its full dependence o

the unique capabilities of the Deep Space Network for success. Similar review proces

es applied to the use of DSN facilities for cooperative VLBI experiments with oth

agencies in the United States and Europe.

Antenna Utilization for Radio Astronomy

The numerous agreements, directives, and requirements for radio astronomy suppo

accumulated through the intervening years, were brought up to date by Larry N. Duma

director of the TDA office at JPL in 1990. With the agreement of the program offi

at NASA Headquarters, Dumas established new limits for the DSN antenna time th

would be applied to radio astronomy throughout the Network.

526

Uplink-Downlink: A History of the Deep Space Networ
NASA- and RAES-approved experiments would not exceed 3 percent of the antenn

time available at any operational DSN station. NASA/CSIRO cross-support experimen

using DSS 43 would receive a minimum of 108 hours per year through August 199

with a 34-m antenna-hour equivalence of two for one. Host Country experiments wou

not exceed 3 percent of the time available at any one of the stations available at ea

complex (approximately 250 hours per year). 

The new guidelines formed the basis for scheduling DSN resources for radio astron

my support thereafter.

A summary of antenna utilization for the ensuing ten years, given in the table belo

reveals how well the guidelines were followed in the operational environment that pr

vailed through the Network in those years.

The figures represent hours of observing time on the 70-m and 34-m DSN antenn

and represent the fulfillment of the 1988 guidelines discussed above. 

Radio Astronomy in the Deep Space Network: 1987–97

(Observing Antenna Hours)

Year JPL/NASA Guest Other* Total

1997 1,999 253 712 2,964

1996 2,735 129 4,691 7,555

1995 1,884 115 1,201 3,200

1994 1,196 531 1,316 3,043

1993 1,379 234 1,086 2,699

1992 1,947 217 1,496 3,660

1991 1,733 128 887 2,748

1990 1,189 147 573 1,909

1989 1,491 57 199 1,747

1988 793 19 13 825

1987 667 35 203 905

* Included Host Country, Space Geodesy, CSIRO Cross-Support

The unusually large amount of time devoted to other institutions and JPL/NASA pr

grams in 1996 reflects a substantial JPL/CSIRO effort devoted to the development 

a new wideband spectrum analyzer for radio astronomy at Canberra and Goldstone, 

addition to normal observation time. 

52

The Deep Space Network as a Scientific Instrument
The DSN Also Benefits 

Without question, the science of radio astronomy has benefited enormously from th

resources made available to it by the Deep Space Network since the advent of the fir

64-m antenna in 1966. 

However, radio astronomy was not the only beneficiary of this association with the DSN

There was a less obvious, but no less substantial, benefit that accrued to the DSN fro

its association with radio astronomy.

In a 1994 white paper on the role of radio astronomy in the DSN, Thomas B. Kuip

then DSN Program Manager for radio astronomy in the DSN Science Office, address

this subject.18 He cited the following examples of technology, methodology, and oper

tional innovation that, currently used in various forms by the DSN, were attributab

to the use of the DSN by radio astronomers:

• digital spectrometers (Goldstein, 1963),

• very long baseline interferometry (Moffet, Ekers, Robertson, 1967),

• antenna calibration with natural radio sources (Klein, 1972),

• connected element interferometry (Gulkis, Jauncey, 1979),

• antenna pointing models (Peters, Ruis, 1982),

• K-band masers (Gulkis, Kuiper, Jauncey, 1982), and

• Internet service to deep space Complexes (Kuiper, 1993).

In addition to its scientific merit, radio astronomy, by its association with other prestigio

scientific institutions and the technical challenges it brought with it, stimulated the inte

est of many talented professionals in all areas of the DSN. DSN capabilities were extende

seldom-used functions were exercised and maintained; and new developments were fiel

tested in the less demanding risk environment of radio astronomy. It provided an intellectua

rewarding, nonoperational environment in which to explore new ideas and new techn

logical development. As Kuiper pointed out, “Radio astronomers would accept lower reliabili

to achieve performance improvement, thus giving the DSN the valuable opportunity 

evaluating and developing experience with new technologies in noncritical operations.”

At that time (1994), Kuiper continued, “the key DSN technologies of antennas an

receivers and radio astronomy were nearing maturity, and the next dramatic innovatio

would come from other technologies, such as information management, automatio

and networking. As applied to radio astronomy in the DSN, these technologies cou

lead to unattended observations, remote operation and monitoring, and noninterferen

528

Uplink-Downlink: A History of the Deep Space Networ
with tracking operations. Because of lower reliability requirements, these new techniqu

could be rapidly integrated into the radio astronomy capability of the DSN for eval

ation, before adapting them for operational use.” That appeared to be the pathway 

the future for radio astronomy in the DSN, and so it proved to be. 

By 1997, the DSN had created a world-class facility for radio astronomy research

When operated at their highest potential frequencies, the DSN antennas equaled 

exceeded the capabilities of the best radio telescopes of the time. A well-document

site on the World Wide Web encouraged potential investigators worldwide with a pleth

ra of technical descriptive material, along with interactive instructions to propose experimen

using the radio astronomy resources of the Deep Space Network.

NOTE: The DSN resources available to potential investigators in radio astronomy were describe

online at http://dsnra.jpl.nasa.gov/.

As an instrument for radio astronomy research, the DSN was highly regarded by th

international science community and had become a visible tribute to NASA’s contin

ing commitment to international science. Encouraged by the radio astronomers that us

it, the DSN continued to improve in the knowledge that radio astronomy research wou

quickly adapt new opportunities in deep space communications technology to furth

its scientific objectives.

Significant Advances

In the role of a scientific instrument for radio astronomy research, the DSN contribut

much to the field over the years 1967 to 1997. As a measure of this contribution, th

DSN lead radio astronomer, Thomas Kuiper, selected the following published papers 

representing significant advances in science over the period 1967 to 1997.20 Incidental

these examples reflected not only advances in scientific knowledge, but advances in th

DSN’s capability to collect and process the data on which such achievements were base

Significant advances in radio astronomy using DSN antennas include the following:

1967: First intercontinental very long baseline interferometry (VLBI).

Fine details in the structure of radio sources can be resolved by combining th

signals from distantly separated radio telescopes (VLBI). The greater the separ

tion, the finer the details. Gubbay and others performed VLBI measuremen

using baselines of intercontinental dimensions. Prior to this, VLBI had been lim

ited to telescopes in North America.21

52

The Deep Space Network as a Scientific Instrument
1969: Pulsar observations at 2,295 MHz (13-cm wavelength), highest frequency to dat

Moffet, Ekers, and others used the Goldstone 64-m antenna at S-band (2,29

MHz) to determine the polarization characteristics of a number of pulsars. A

higher frequencies, pulsar signals are less affected by the interstellar medium throug

which they pass on their way to Earth.22

1969: Detection of the first jump in the period of the Vela pulsar.

Reichley, Downs, and others detected a sudden increase in the period of the Ve

pulsar while monitoring the period of a set of pulsars with the Goldstone 64-

antenna. They attributed the jump to the settling of the matter of the neutro

star, similar to an earthquake.23

1971: Discovery of superluminal motions in 3C273 and 3C279.

By comparing the images made at two different times using the VLBI techniq

(see 1967), Clark and others showed that matter in these objects appeared to 

moving with a speed greater than the speed of light. Later, this was understoo

as an illusion due to the orientation of matter flow and the effect of relativity

1973: Best upper limit to date on cosmic background small-scale anisotropy.

The currently clumpy distribution of matter in the universe, in stars and gala

ies, and clusters of galaxies evolved from a very smooth initial distribution accordin

to radio astronomer Carpenter. Explaining this remained (in 1997) a challen

for the cosmologists.25

1982: Most distant quasar discovered with Tidbinbilla interferometer.

Using a radio interferometer consisting of two antennas at NASA’s Canber

(Tidbinbilla) Complex, Batty, Jauncey, and others determined precise positio

for a large number of radio sources. This allowed these sources to be associat

with optical objects which were then identified. One of them turned out to 

the most distant quasar known to that time.26

1986: First space-based VLBI with TDRSS antenna.

As a proof of concept, Linfield, and others used the DSN antennas with a NAS

Tracking and Data Relay Satellite to make VLBI (see 1967) observations of thr

quasars. In addition to obtaining finer detail than ever before, this demonstra

ed that VLBI baselines could be larger than the diameter of Earth.27, 28

530

Uplink-Downlink: A History of the Deep Space Networ
1992: First speckle hologram of the interstellar plasma.

Desai, Gwinn, and others used an array of Southern Hemisphere antennas, inclu

ing two at NASA’s Canberra Complex and two former DSN antenn

(Hartebeesthoek, South Africa, and Hobart, Australia) to observe the Vela puls

Correlations in the time variation of the Vela data from the various stations we

analyzed to obtain information about the structure of the interstellar medium

1995: First images of motion in the nearest active galactic nucleus.

Over a period of eight years, Tingay, Jauncey, and others carried out a series 

VLBI observations using telescope arrays including NASA 70-m antenna

Through these observations it was learned that jets of plasma flow out of th

core of Centaurus A. The behavior of this core was thought to be typical of oth

more distant active galactic nuclei.30

1995: First image of infall of cloud material onto a protostar.

A protostar is a star that is still growing by accreting matter from the cloud o

of which it formed. Vellusamy, Kuiper, and Langer, by combining data from th

Goldstone 70-m antenna with data from the Very Large Array, made images 

the material falling onto the protostar B335. Neither telescope by itself cou

have produced such images.31

1996: First evidence for the formation of a preprotostellar core by coagulation.

By comparing Goldstone 70-m data with VLA data, and comparing the resu

with those obtained with other telescopes, Kuiper, Langer, and Vellusamy foun

the cloud core L1498 to be growing by the process of accreting material. Th

cloud was not collapsing like B335 (see above), but was thought to be growin

towards a stage when collapse would occur. Prior to this, it was not know

whether prestellar cores grew by slow accretion of surrounding material.32

1996: Nano-arcsecond resolution of the Vela pulsar.

Using interstellar scattering data derived from further analysis of the speckle da

obtained in 1992 (see above), Gwinn and others determined the size (approx

mately 500 km) and approximate shape of the emitting region of the Vela pulsar

1997: First VLBI astrometric detection of an unseen companion star.

Guirado, Reynolds, and others used the 70-m antenna at NASA’s Canber

Complex, combined with the (former DSN) 26-m radio astronomy antenna 

Hobart, Australia, and the 64-m radio astronomy antenna at Parkes, Austral

to make precise measurements of the position of the star AB Doradus. A wo

53

The Deep Space Network as a Scientific Instrument
bling in the positions of the star revealed the presence of a dark companion wi

about a tenth of the mass of the Sun.34

1997: First images from the HALCA Space VLBI mission.

The Japanese HALCA space telescope was the first dedicated orbiting VLBI ante

na. Its orbit was chosen to provide the longest baselines to that date. The NAS

70-m antennas, because of their size and geographic locations, played an impo

tant role as a ground element in the HALCA mission to produce extremely sensiti

and detailed images of compact radio sources. 

532

Uplink-Downlink: A History of the Deep Space Networ
THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE (SETI) 

In the late 1970s, against a background of serious scientific interest in the detection 

extraterrestrial intelligence dating back to the early 1960s and strong advocacy by sc

entists at Jet Propulsion Laboratory and the Ames Research Center, NASA initiated 

formal program to search for evidence of extraterrestrial intelligence. Under the acrony

SETI (Search for Extraterrestrial Intelligence), the program was to be managed by th

Astrophysics Division of the NASA Headquarters Office of Space Sciences (OSS). 

SETI was to be a research and development program aimed at demonstrating the ne

essary technology to search a well-defined volume of sky and frequency space, within 

finite time, for evidence of intelligent signals of extraterrestrial origin. It was to use exis

ing antennas augmented with new spectrum analysis and data-processing systems.

In June 1980, TDA progress reports by Robert E. Edelson and Gerry S. Levy35 descri

ing the telecommunications technology associated with SETI, and by Berman36 describin

the SETI observational plan, reflected the growing involvement of the TDA Office 

the new program. Both of these reports drew attention to the dependence of the pr

posed SETI program on the use of existing large antennas, ultra-sensitive microwa

receiving systems, identification of terrestrial sources of radio frequency interference (RF

and wideband spectrum analysis and data management technology, most of which w

to be found in the existing Deep Space Network. Although not explicitly stated, the

was also perceived to be a symbiotic relationship between the new technology that wou

be needed for SETI and that which the DSN would use for wideband signal acqui

tion, and RFI and spectrum management. These were the principal factors th

established a basis for the DSN association with the SETI program. 

Supported by funding from the NASA Office of Space Science and, to a lesser exte

by funding from the NASA Office of Tracking and Data Acquisition, the SETI pr

gram at JPL was carried forward as a parallel but independent program to that of th

Deep Space Network. Within JPL, the SETI program was managed by the TDA Scien

Office under the direction of Nicholas A. Renzetti. 

In the overall plan, two parallel but complementary strategies were to be used to condu

the SETI observations—a “targeted survey” and an “all-sky survey.” The targeted surv

would target approximately 800 to 1,000 candidate stars within 100 light-years of Eart

It would search for pulsed or continuous signals in the 1- to 3-GHz frequency band an

would require high-sensitivity, narrow-bandwidth data acquisition systems that would 

used with the 64-m DSN antennas and the NRAO 305-m antenna at Arecibo, Puer

53

The Deep Space Network as a Scientific Instrument
Rico. The “all-sky survey” would trade lower sensitivity for the ability to survey 99 perce

of the sky that was not covered by the targeted search, and it would span a wider frequen

range, from 1 to 10 GHz. It would be conducted on the DSN 34-m antennas. 

Working within these broad objectives and guided by a SETI Science Working Grou

that had been set up by NASA at the outset of the SETI program, engineers at JP

began to develop the elements of hardware and software based on Fast Fourier Transfor

(FFT) techniques that would be required for both strategies.37 It should be made cle

at this point that the engineering groups doing this work for the SETI program wer

at the same time, doing similar work for the DSN. Although the funding sources we

different, the organizations were one and the same, and the benefits of the DSN tec

nology base obviously accrued to the SETI program.

The objective of this effort was to be a field demonstration at Goldstone, using the DS

13 antenna and known sources of radiation such as NASA planetary spacecraft. 

The first step in this direction was to assess the radio frequency interference (RFI) env

ronment in which the sky survey would be carried out. The resulting data base wou

reveal the incidence of false signals and the presence of interfering signals and noise—

information that would be essential to the design of the final signal-detection, analys

and data-processing equipment for SETI.

For this purpose, a Radio Spectrum Surveillance System was built, mounted in a transportab

van with a 1-meter-diameter antenna, and deployed at Goldstone in 1984.38 The syste

comprised seven low-noise Field Effect Transistors (FETs) to cover the range of frequenci

1–10 GHz; a commercially available, programmable, swept-frequency spectrum analyzer; an

a floppy disc storage device. These were all controlled by a BASIC software program. 

addition to its primary use by the SETI program, the RFI van proved to be a remarkab

effective facility that was subsequently used for many years by DSN spectrum manageme

engineers to continuously monitor and identify RFI in the deep space bands at Goldston

The initial field demonstrations for SETI, using FFT-based hardware and software, bega

at DSS 13 in March 1985.39 The field-test instrumentation consisted of the DSS 13 2

m antenna with low-noise receiving systems for the 2,200- to 2,290-MHz and 8,40

to 8,500-MHz bands. It also included a 65,000-channel FFT spectrum analyzer, design

and built by JPL and housed in the RFI van, which was parked nearby. A 72,000-cha

nel Multichannel Spectrum Analyzer, designed and built for ARC at Stanford Universi

for the targeted search program, was also part of the field demonstration. The detectio

strategy and configuration used for the sky survey field tests is shown in Figure 8-4.

534

Uplink-Downlink: A History of the Deep Space Networ
53

The Deep Space Network as a Scientific Instrument

Figure 8-4. Detection strategy and system configuration for the SETI sky survey field tes

1985.

SCAN 

PATTERN

RESPONSE

AT

FREQ ν

CONVOLUTIONAL

FILTER THRESHOLD

DSS 13 AT JPL

OFF-LINE

COMPUTER

TAPES TAPES

FLOPPY

DISK

FLOPPY

DISK

FLOPPY

DISK

65,000 CHAN FFT ANALYZER

MONITOR

AND 

CONTROL

RECEIVER

RFI

ANALYZERSYSTEM

SETI RSSS

RFS SUSBSYSTEM

MICROWAVE

HARD

DISKS

Sky survey detection strategy

System configuration for Sky Survey field tests (1985)

CONFIRMATION

SETI

EVENT

?

EVENT FILE

• SAVE

ASTRONOMY

DATA

• DISCARD RFI

Y

N

δ

α

α, δ, S, ν, ... 

HA

δ
The tests were based on the detection of narrow-band signals from the Voyager an

Pioneer spacecraft, which, in well-defined celestial locations, provided low-level signa

with known characteristics perfectly suited to the evaluation of the basic SETI system

Typical spectrum analyzer displays for the detection of Pioneer 11 and Pioneer 12 spac

craft signals are shown in Figure 8-5.

For the next two years, the field-test program was used to verify hardware designs, fu

ther develop signal-detection strategy and automated procedures, and characterize th

RFI environment at the site over the range of 1 to 10 MHz. 

In April 1987, a program plan proposing separate but complementary search strategi

was presented to NASA by representatives of the SETI program from ARC and JP

The two Field Centers jointly proposed to develop and operate observing systems usin

high-speed signal-processing equipment that could be used in conjunction with existin

ground-based radio astronomy and deep space communication facilities. The target

536

Uplink-Downlink: A History of the Deep Space Networ

Figure 8-5. SETI detection of spacecraft signals, 1985.

35

33

300

200

100

200 • SYSTEM:

• DSS 13 26-METER ANTENNA

• DSN FFT SPECTRUM ANALYZER

• SETI CONFIGURATION AT 2295 MHz

• SPACECRAFT DISTANCES (MARCH 1985)

• PIONEER 11.....280 X 107 KM

• PIONEER 12.........6 X 107 KM

100

0

TEST

SIGNAL

PN 11

306 Hz

PN 12

256 Hz

32 Hz

0

31

-75 -50 -25 0 +25 +50 +75 -100 -50 0 +50 +100

-8 -6 -4 -2 0 +2 +4 +6 +8

∆ FREQUENCY, KHz ∆ FREQUENCY, KHz

∆ FREQUENCY, KHz

TSYS, K

TSYS, K
search was to be the responsibility of ARC, while JPL would be responsible for the a

sky survey. ARC would act as the Lead Center for the program, which would be manag

by the Life Sciences Division of OSS with important technical and financial suppo

from the Office of Space Communications (OSC, formerly OTDA). The DSN wou

provide support on its 34-m antennas for the all-sky search and time on its 70-m ante

nas for those parts of the targeted search that could not be provided by the Arecib

antenna or the NRAO antenna. With this decision made, the JPL team focused 

efforts on the development of equipment and techniques that were optimized for th

all-sky survey. Henceforth, the newly directed program would be known as the Hig

Resolution Microwave Survey (HRMS).

Building on search strategies and FFT techniques that had been developed while th

initial demonstration field tests were in progress at Goldstone,40 a more refined sign

detection strategy for an operational HRMS all-sky survey evolved, and a much larg

wide-band, high-resolution spectrum analyzer (WBSA) had been designed.41 These an

the observing procedures derived from the field tests experience at Goldstone would 

assembled into a prototype system and used for a limited proof-of-concept search pr

gram to be conducted in the early 1990s. Experience gained from these proof-of-conce

tests would be used to improve the design of the full-scale operational system, whi

was then scheduled for completion in 1996.

The objective of the all-sky survey was to search the entire sky over the frequency ran

from 1.0 to 10.0 GHz for evidence of narrow band signals of extraterrestrial origi

Frequency resolutions as narrow as 20 Hz were required. The objectives of the surve

as presented by Coulter Klein and others are summarized in the table below.

Characteristics of the All-Sky Survey for a 34-m Antenna

Spatial coverage 4 pi steradians (full sphere)

Frequency coverage 1–10 GHz with higher spot bands

Duration of survey 5–10 years (7-year goal)

Dwell time per source 0.5 to 10.0 seconds

Frequency resolution 10–30 Hz

Sensitivity, (allowing for spatial Approx. 10-23 watts/meter2

uniformity and variation with 

frequency)

Polarization Simultaneous dual circular

Signal type Continuous Wave (CW)

53

The Deep Space Network as a Scientific Instrument
To accommodate the limited observing time that would be available on the DSN 34-

antennas for HRMS, an antenna scan pattern of “racetrack” form was developed. Th

racetrack scan pattern utilized the available antenna time efficiently, maintained max

mum sensitivity with uniformity across each sky frame, and facilitated the signal detectio

process. Specific features of this pattern could also be used to discriminate against ce

tain types of RFI.

In collaboration with the DSN Advanced Systems Program, an engineering developme

model of a wideband spectrum analyzer (WBSA) was built to serve as a prototype f

the final operational model. This machine was key to the design of the HRMS system

The WBSA featured a pipelined FFT architecture that transformed 40 MHz of inp

bandwidth into 20-Hz wide bins in the frequency domain. To accommodate the wi

bandwidth in real time, the WBSA performed 4.5 billion operations per second an

used two input channels to search simultaneously for left and right polarized signa

The output of the WBSA was passed to a signal-detection module that performed bas

line estimation, filtering, and thresholding functions. Although the prototype syste

bandwidth was limited to 20 MHz, plans were made to increase this to 320 MHz 

the final operational design in order to complete the survey in 7 years. It would ha

taken 100 years to complete the survey with a 20-MHz bandwidth.

Progress in developing the two parallel systems at JPL and at ARC was such that on 1

October 1992, the observational phase of HRMS was inaugurated with simultaneou

coordinated observations of a selected sky frame by the all-sky system at DSS 13, an

a star within that frame by the targeted-search system at Arecibo. The occasion w

marked with appropriate pomp and circumstance, and keynote addresses were deliver

by SETI pioneers Philip Morrison (at Arecibo) and Carl Sagan (at Goldstone). The u

of the recently completed 34-m BWG antenna at DSS 13 added to the significance 

the event.

A view of the eastern sky as seen from Goldstone at noon on that day is shown 

Figure 8-6. The shaded areas define the boundaries of the first two sky frames of th

HRMS Sky Survey. The location of the first star observed by the Targeted Search Tea

at Arecibo is shown in sky frame number 1.

The initial surveys were conducted near 8.5 GHz to characterize the system operatin

performance and determine the RFI environment and the system’s ability to discrim

nate against it. Later, repeated observations of a set of three sky frames at other, low

frequencies provided data of interest to the radio astronomy community, as well as th

538

Uplink-Downlink: A History of the Deep Space Networ
HRMS program, and allowed further improvement in the efficiency of the signal-pr

cessing algorithms that reduced the effects of RFI. During the first year of observation

no signals from beyond our solar system were detected by either the sky-survey or th

targeted-search systems. However, many valuable lessons had been learned and we

about to be incorporated into the full operational system. Confidence in and enthu

asm for the HRMS program were high.

Suddenly, in October 1993, the U.S. Congress unexpectedly terminated the program o

the grounds of financial expediency. Apart from preserving the advanced signal-proces

53

The Deep Space Network as a Scientific Instrument

Figure 8-6. The first HRMS sky survey, Goldstone, 12 October 1992. 

BOOTES

CORONA

BOREALIS

HERCULES

OPHIUCHUS

LIBRA

VIRGO SKY 

FRAME No. 2

SKY 

FRAME No.1

TARGET STAR No. 1

M13

M5 MERCURY

SUN

VENUS

EAST SE
ing systems for potential future use, no further work was possible and all HRMS obse

vations with the sky-survey equipment were terminated by the end of 1993.42 

Subsequently, the prototype sky survey system was redirected for further developme

and use in the operational Deep Space Network. The SETI initiative was continued b

the SETI Institute of Mountain View, California, a corporation devoted to the sear

for extraterrestrial intelligent life and to research relevant to the disciplines of life in th

universe. Its purpose included the conduct and promotion of public information an

education as it related to SETI. To this end, it sought private donations to continue th

development and use of the targeted survey system at the Arecibo Observatory in Puer

Rico.

540

Uplink-Downlink: A History of the Deep Space Networ
CRUSTAL DYNAMICS

By the early 1970s, very long baseline interferometry (VLBI) was well established in th

DSN as a technique for spacecraft navigation, radio astronomy observations of the stru

ture and position of Extra Galactic Radio Sources (EGRS), and the determination 

baseline vectors between fixed reference points on Earth (DSN tracking stations). Succe

in these areas gave rise to an increasing interest by the science community in applyin

VLBI techniques to accurate measurements in the fields of geodynamics and geodesy

However, the fixed antennas of the DSN were not suited to the conduct of an exte

sive geodetic monitoring program that would require frequent and accurate measuremen

along many reference baselines. For this purpose, a mobile facility, which employed th

same VLBI techniques but possessed an added capability for rapid deployment to nume

ous selected sites of geodetic interest, was required.

To this end, in 1971, the NASA Office of Applications funded a research program 

demonstrate the capabilities of portable, independent-station radio interferometry. Becau

of its relationship to well-established DSN technology and its dependence on the 64-

DSN antenna at Goldstone as a reference point, the program was assigned to JPL and w

managed by the Telecommunications and Data Acquisition Office, with Nicholas A. Renze

as the Program Manager. It was named Astronomical Radio Interferometric Earth Surveyin

(ARIES) and was led by P. F. MacDoran. 

By refurbishing a surplus 9-meter transportable antenna and implementing the nece

sary instrumentation in trailer-mounted vans, a transportable ARIES facility was rapid

assembled and, by the end of 1973, was ready to start field operations at Goldstone

The initial series of experiments were performed by Ong, MacDoran, and others, on 

short 307-meter baseline over the period from December 1973 to June 1974, usin

ARIES as one observing station and DSS 14 as the other. The arrangement is illustra

ed in Figure 8-7.

Use of a short baseline for the initial tests enabled a comparison of conventional surv

methods with few-centimeter accuracy to minimize interferometry errors due to tran

mission media effects, source locations, and Earth orientation parameters. The resul

representing approximately 28 hours of data, were in excellent agreement with the su

vey baseline in all dimensions within the formal uncertainty of 3 cm.43 Over the ne

five years, ARIES was moved to various locations in the western United States to refin

54

The Deep Space Network as a Scientific Instrument
and demonstrate the feasibility of the mobile VLBI concept and to initiate studies 

crustal motion on a regional scale.

The success of this program eventually led to a requirement for two additional mob

VLBI units and a dedicated base station for the Crustal Dynamics project. The desig

and construction of the mobile units and implementation of the Mojave Base Statio

at Goldstone were carried out by Brun, Wu, and others as part of the ORION proje

by the DSN in 1982.44, 45

The Mojave Base Station utilized a redundant 12.2-meter antenna and Control Roo

built in 1962 to support a communications satellite program operated by the Godda

Space Flight Center. In June 1983, after major refurbishment by a joint JPL and GSF

engineering team, the Mojave Station, operated by Bendix contractor personnel, bega

to support the Crustal Dynamics project. The completion of this station relieved DS

stations DSS 14 and DSS 13 from the burden of supporting the Crustal Dynamics fie

observing program. The two mobile VLBI (MV) units, which used much smaller ante

542

Uplink-Downlink: A History of the Deep Space Networ

Figure 8-7. Project ARIES transportable antenna interferometer system.

EXTRAGALACTIC

RANDOM RADIO

SIGNALS

DIFFERENCE IN

TIME OF ARRIVAL

BASELINE

VECTOR

MAGNETIC

TAPE

CROSS CORRELATION

SIGNAL DETECTION

(MINI-COMPUTER)

STOPPED

FRINGES

PHASE

TRACKING

BANDWIDTH

SYNTHESIS

(GEN PURPOSE

CIMPUTER)

DELAY,

DELAY

RATE

OBSERVABLES

SIMULTANEOUS

MULTI-PARAMETER

SOLUTION

(GEN PURPOSECOMPUTER)

BASELINE

VECTOR

CALIBRATIONS

TRANSPORTABLE

ANTENNA
nas and were more readily transportable than the original ARIES, started observing 

1980 and 1982, respectively.

Between 1980 and 1985, the three MV units, in conjunction with Mojave and se

eral other fixed base stations in the western United States, were operated as part of 

surveying program to determine the relative motions and regional strain fields ne

tectonic plate boundaries in California and Alaska. The results of this effort, and th

difficulties encountered in realizing the necessary accuracy to deliver viable data, a

described by J. M. Davidson and D. W. Trask, who led the effort for the TDA Offi

at JPL.46 They reported that “baseline measurements utilizing the current Mobile VLB

systems had attained an accuracy of 2 cm, or better, in the horizontal plane” an

observed that “since average geological rates of horizontal motion are on the order 

5 cm/yr across the plate boundary regions being studied, it was likely that crust

motion would be detected within the next few years, provided [it was] occurring 

the geological rates.”

The mobile VLBI project at JPL had reached the point where it could be transferr

to its ultimate user, the National Geodetic Survey (NGS)/National Oceanic an

Atmospheric Administration (NOAA) and Goddard Space Flight Center (GSFC). Th

transfer was completed in 1984 and 1985.

Even as the more economical, portable VLBI stations of the ORION task we

under construction, technologists were experimenting with a new, potentially low

cost method for measuring Earth crustal deformation. This method utilized th

L-band signals transmitted by the Global Positioning System (GPS), a constell

tion of 24 Earth-orbiting satellites under development in the 1980s by th

Department of Defense. Unlike the weak quasar signals recorded by VLBI, the GP

signals broadcasted at 1.2 and 1.5 GHz were relatively strong and did not requi

9-m antennas and low-noise receivers for their acquisition. A system based on GP

technology, therefore, offered the promise of high performance, low cost, and muc

greater mobility than the MV system. It would, in addition, have very significa

application to the existing DSN for spacecraft navigation and other purposes rela

ed to station locations. With this in mind, the Geodynamics Program funded JP

for an experimental demonstration of the new GPS technique. It started with th

Satellite Emission Range Inferred Earth Survey (SERIES) project in 1979, also und

the leadership of Peter F. MacDoran.47

Under the SERIES project, two GPS receivers were built at JPL for proof-of-conce

measurements on short baselines. These receivers measured the differential group del

54

The Deep Space Network as a Scientific Instrument
of signals transmitted at two different frequencies from the GPS satellites. This info

mation could be used not only to determine the location of the receiver on Earth

surface to a level of precision approaching that of the mobile VLBI system, but al

to calibrate the ionosphere in terms of the total electron content (TEC) along th

line of sight between the receiver and the satellite. The former function and oth

data derived from it was of particular interest to the Geodynamics Program for shor

baseline geodetics measurements, while the latter function was of particular intere

to the DSN for adding media calibrations to the radio metric data used for spac

craft navigation. 

While the SERIES project successfully demonstrated the potential of the new GPS tec

nology, it also showed the need for a more compact receiver with enhanced capabili

for deployment at multiple field sites. At that time, receivers that had a capability f

parallel processing of signals from four (or more) satellites simultaneously and were su

ficiently portable for field applications were not available commercially. It was this situatio

that led to the development of the SERIES-X receivers at JPL, starting in 1982 und

the direction of William G. Melbourne.

The SERIES-X design was also very promising as an instrument for continuous, preci

ionosphere calibrations at each DSN Complex. The Faraday Rotation satellites (ATS-6

which had been used for this purpose for many years, were rapidly being decomm

sioned. The GPS technique offered a cost-effective, more accurate means of calibratin

radio metric tracking data. The DSN proposed to implement GPS receivers at ea

Complex and to develop the data retrieval system and software required to produce th

calibrations for the inflight projects. An upgrade to the SERIES-X design was develop

for this purpose. The receivers that were actually installed at the three complexes we

built by a commercial partner, Alan Osborne Associates (AOA), and were referred to 

the “Rogue Receivers.”

Under the auspices of the NASA Geodynamics program, the Rogue Receivers were us

for geodetics measurements and, as part of the JPL Crustal Dynamics project, to demo

strate the concept of a Fiducial Network.48, 49 Within the DSN, they were used specifical

to determine the total electron content of the ionosphere50 for radio metric data ca

bration purposes.

Following the implementation of the Rogue Receivers in the DSN, further developme

of GPS receivers shifted to the Geodynamics program. The Rogue Receivers were pr

duced commercially by AOA and were used in a number of field campaigns in the mi

to late 1980s. The first campaigns to use the GPS system were conducted in 1985 wi

544

Uplink-Downlink: A History of the Deep Space Networ
baselines in Mexico and the Caribbean regions. Data from the DSN Rogue Netwo

were used to establish a terrestrial reference frame for these experiments. It was the

experiments which clearly demonstrated the economics of GPS Geodesy and spark

further development of GPS technology for the Geodynamics program. 

As the SERIES-X program got under way, another sponsor for GPS technology emerg

in the form of the TOPEX project. Managed by JPL and planned for launch in 198

TOPEX was an Earth-orbiting satellite dedicated to the study of ocean topograph

TOPEX carried, amongst other scientific instruments, a highly accurate radio altim

ter for the measurement of ocean surface height (sea altitude). To meet the specifie

goal of 10-cm altitude accuracy, a very precise knowledge of the spacecraft orbit w

required, and the use of the system then available would have resulted in an acc

racy of ±14 cm. 

In a proposal to the TOPEX Project in July 1984, the TDA Science Office describe

a system by which the accuracy could be increased to ±2.4 cm using GPS.51 Th

proposal called for a flight-qualified GPS receiver and antenna aboard the TOPEX spac

craft, a SERIES-X (Rogue) ground receiver at each DSN Complex, and at least thr

ground receivers at other remote locations. It also included a data communications ne

work and a central data processing facility to provide the TOPEX precision orb

determination functions. The underlying concept of the demonstration was that an inflig

GPS receiver could, in conjunction with precisely located GPS ground stations, be us

for highly accurate determination of orbiting satellites in an Earth-based reference fram

Orbit determination for TOPEX, replacement of the Mobile VLBI stations for Crust

Dynamics, and ionosphere calibration for the DSN became the three principal drive

for further GPS-based development, and funding was shared accordingly by the respe

tive program offices.

GPS-based technology was formally introduced into the operational capability of th

DSN in November 1986 with a Functional Design Review for a new Media Calibratio

Subsystem for the DSCCs.52 At each Complex, the new DSCC Media Calibratio

Subsystem (DMC) would perform continuous measurements of local ground weath

parameters in addition to generating differential P-code group delay and carrier pha

from the GPS satellites. These data were to be recorded and transmitted from the Complex

to the NOCC at JPL for the use of the Navigation Team in calibrating the radio me

ric data delivered by the DSN Tracking system. A description of the GPS system 

beyond the scope of this book, but the essential elements as they applied to the DM

in 1986 are shown in Figure 8-8.

54

The Deep Space Network as a Scientific Instrument
546

Uplink-Downlink: A History of the Deep Space Networ

Figure 8-8. Global Positioning System, 1986. The GPS functions of the DMC were carried out by SERIES-X (Rogue) receivers, which acquired and simultaneously tracked the two GPS L-band carriers from at least four satellites, extracted the ephemeris data from each, and measured the differential P-code group delay and the carrier phase. Because of the sensitivity of the military to the use of the NAVS- TAR system for other than classified purposes, these operations were performed without an explicit knowledge of the classified P-codes themselves. • GLOBAL POSITIONING SYSTEM • 18 SPACE VEHICLES PLUS 3 SPARES • SPACED 60° (LONGITUDE) APART • INCLINATION 55° • 6 ORBITAL PLANES • 120° BETWEEN SPACE VEHICLES IN PLANE • 40° BETWEEN SPACE VEHICLES PLANE-TO-PLANE • CESIUM STANDARDS WITH LONG-TERM ∆f/f OF 5 PARTS IN 1014 PER DAY RCS THRUSTERS INJECTION MOTORSOLAR ARRAY HEAT TRANSFER LOUVERS 12 HELICAL SHAPED BEAM L-BAND NAVIGATION ANTENNA EARTH SENSOR TT&CS S-BAND ANTENNA EARTH POINTING
The basic principle of GPS-based ionospheric calibration is illustrated schematically 

Figure 8-9.

The remarkable performance of the receivers is reflected in the following estimates f

their accuracy in determining TEC:

Performance of the DMC for Ionosphere Calibration Using GPS 

Differential delay Precision (el/m2) Accuracy (el/m2)

P-code groups 1 x 1016 5 x 1016

L2-L1 carrier phase 0.02 x 1016 0.02 x 1016

NOTE: Total Electron Content (TEC) of the ionosphere is measured in units of electrons per square meter (el/m2). 

The DMC was put into operation at each of the three complexes in 1989 and imm

diately became the DSN standard source for ionosphere calibration data. Eventually, th

54

The Deep Space Network as a Scientific Instrument

Figure 8-9. Schematic view of GPS-based ionospheric calibration.

TRANSMITTER

TRANSMITTER OFFSET

IONOSPHERE

L2

L1

IONOSPHERIC DELAY

PLUS TRANSMITTER

OFFSET

RECEIVER
original Rogue Receivers were replaced by smaller, laptop computer-size receivers, know

as the Turbo-Rogues. The first of the Turbo-Rogues to be produced were installed 

the DSN Complexes, and as they became available, the Turbo-Rogues gradually replac

the original receivers within the NASA GPS Global Network also.

By 1988, GPS technology sponsored by JPL had become a significant new tool f

Geodynamics research on short baselines and as a complementary technique to VLB

for measurements on long (intercontinental) baselines. At the same time, the Crust

Dynamics project at GSFC was operating a Satellite Laser Ranging (SLR) System an

a VLBI System (using DSN antennas as well as international VLBI stations) and had 

large budget for that purpose. By comparison, the JPL budget for GPS applications 

Crustal Dynamics was very small. With time, it became apparent that GPS could n

only determine short baselines almost as accurately as VLBI, but was also approachin

VLBI performance on the long baselines, and some reassessment of the relative value 

GPS to the NASA Geodynamics program was called for.

To this end, a conference of all parties involved in the Geodynamics program was co

vened by the NASA program manager at Coolfont, West Virginia, in July 1989. F

Geodynamics Solid Earth studies, the Coolfont conference recommended the establis

ment of a backbone consisting of a multicountry, intercontinental network of VLB

stations colocated with fixed GPS stations. The VLBI network would maintain a stron

inertial reference for Earth rotation studies and provide precise measurements over inte

continental distances for the study of tectonic motion. The VLBI stations would al

be complemented with a multicountry network of roving GPS stations for making mea

urements on short baselines for crustal motion studies.

Thus, Coolfont represented a major turning point for the Geodynamics program in ge

eral and the Crustal Dynamics project at JPL in particular. As a consequence of th

agreements reached there, the Crustal Dynamics project at JPL was ended and GP

became a permanent and major part of the NASA Geodynamics program with JPL 

the Lead Center for GPS technology. The VLBI technology was pursued by GSFC an

involved JPL only to the extent that the VLBI program needed support from the DS

antennas.53

Under the cognizance of the NASA International Geodynamics Program, the field obser

ing program thus evolved into two components, one based on VLBI and managed b

GSFC, the other based on GPS and managed by JPL. The international VLBI netwo

(which included but was not limited to the DSN 70-m antennas) comprised a set 

permanent sites, each of which had a large radio astronomy antenna colocated with 

548

Uplink-Downlink: A History of the Deep Space Networ
fixed GPS receiver installation. The international GPS network was made up of a Netwo

of portable GPS receivers installed and operated by the observing scientists themselv

in areas of their specific interest. 

So ended the Crustal Dynamics Project, the techniques for which had been founded an

nurtured by the TDA Science Office for fifteen years. Out of this work had grown a bu

geoning GPS technology, which, in addition to its proliferation in the Geodynamics program

was finding increasing applications in the operations of the DSN. The synergy that h

developed between the Crustal Dynamics project and the DSN had given rise to signi

cant improvements in the orbit determination processes on which the DSN, and users 

the DSN, depended for spacecraft navigation purposes. Ionosphere and troposphere ca

brations, Earth-orientation measurements, and intercomplex time synchronization were are

in which VLBI techniques, complemented by GPS techniques derived from the Crust

Dynamics work, had been most effective.

In recent years, the extension of GPS technology to DSN- and spacecraft-related pro

lems, and to non-NASA applications, was sponsored by the TDA Technology Offi

and is reported in the previous chapter.

54

The Deep Space Network as a Scientific Instrument
PLANETARY RADAR

In the context of science in the DSN, it can be stated unequivocally that “in th

beginning, there was planetary radar.” Planetary radar came before radio astronom

before radio science, and before SETI or crustal dynamics became initiatives in th

Deep Space Network. As a matter of fact, planetary radar preceded planetary spac

craft in the DSN. As we shall see, the first planetary radar experiment (Venus) too

place on 10 March 1961, while the first successful planetary spaceflight (Mariner 

took place on 27 August 1962.

Early in 1960, plans were being made at JPL for spaceflights to the inner planets, begi

ning with the Mariner mission to Venus. The DSIF, as it was known at that tim

comprised four antennas with diameters of 26 meters (85 feet): two at Goldstone, Californ

one at Woomera, Australia; and one under construction at Johannesburg, South Afric

Teletype, telephone, and undersea cable communications links tied each of the antenn

sites to a rudimentary Control Center at JPL.

The planetary missions presented many new challenges to existing technology, amon

which was a requirement for hitherto unprecedented accuracy in spacecraft navigatio

To a large degree, spacecraft navigation depends for its accuracy upon the quality of th

Doppler data provided by the tracking stations and a knowledge of the ephemeris 

the planet and the value of the Astronomical Unit (AU). The DSIF was working o

the Doppler data issue, but the accuracy of the Venus ephemeris and the value for AU

based on optical astronomy observations, left much to be desired for planetary navig

tion purposes. With this situation in mind, Eberhardt Rechtin, Walter K. Victor, an

Robertson Stevens proposed to carry out a bold experiment during the 1961 conjun

tion of Venus, using existing facilities at Goldstone to refine the value of the Astronomic

Unit and improve the ephemeris of Venus. Using radar techniques, the round-trip tim

required for a radio signal transmitted from Earth and reflected back from the surfa

of the planet to return to Earth would be measured very precisely. From these and anc

lary data, the desired ephemeris and value for AU could be determined. 

The experiment began on 10 March 1961, in the bistatic mode with one of the Goldston

26-m antennas transmitting (Echo site) and the other receiving (Pioneer site). On 1

March, the Director of the DSIF, Eberhardt Rechtin, announced the success of th

Goldstone Venus Radar Experiment in a message to his colleagues at the MIT Linco

Laboratory, which had for several years previously been attempting to do the same thin

“HAVE BEEN OBTAINING REAL TIME RADAR REFLECTED SIGNALS FROM

VENUS SINCE MARCH 10 USING 10 KW CW AT 2388 MC AT A SYSTEM

550

Uplink-Downlink: A History of the Deep Space Networ
TEMPERATURE OF 55 DEGREES.” The reply from Lincoln Laboratory offered hear

congratulations but reported no success with their own efforts to that time. Once unam

biguous daily contacts with Venus were well established with the ranging system turn

on, measurements of the Earth-Venus distance began and continued through mid-M

1961. Based on these results, Victor and Stevens announced their results to the scie

tific world in Science, July 1961.54 The value for the AU, based on data from the fir

planetary radar experiment, was determined to be 149,599,000 with an accuracy 

±1,500 km. At that time, this represented a major improvement in accuracy compar

to that obtained from optical and other radar-based experiments. After further refin

ment by D. O. Muhleman and others, the uncertainty was reduced to ±500 km b

August and to ±250 km in the following year.

NOTE: The International Astronomical Union adopted the value of 149,600,000 km 

1964, based on the radar method first demonstrated successfully at Goldstone in 1961. F

a detailed account of this event, and of planetary radar in general, the reader is referred 

To See the Unseen by Andrew J. Butrica.55

The new value of the AU and the refined ephemeris resulting from the Venus rad

experiment were immediately put to use for Mariner orbit determination. Later, it w

estimated that without the improved value for the AU and ephemeris improvemen

Mariner 2 would have passed Venus at too great a distance to have returned any usef

data. (Mariner 1 failed on launch.)

In the opinion of historian Andrew Butrica, “The JPL experiment succeeded becau

it did not depend on . . . prior knowledge of the AU. On the other hand, Linco

Laboratory and Jodrell Bank based their experiments on an assumed, yet common

accepted, value for AU and consequently for the distance between Earth and Ven

during inferior conjunction.” The experiment also owed much of its success to the su

stantial improvements in uplink and downlink performance that were made to th

existing equipment built to support the Echo Balloon experiment in August the pr

vious year. Because the power in the return signal from Venus was expected to be 5

dB to 60 dB (100,000 to 1,000,000 times) weaker than had been received from th

Echo balloon, an improved receiving system working with maximum transmitter pow

would be required to detect the Venus signal. 

To meet these requirements, an S-band, low-noise maser and parametric amplifier w

added to the receiver at the Pioneer antenna.56 The single-cavity, three-level ruby mas

the first of its kind, had been developed by Walter Higa at JPL specifically for this app

cation.57 Together with an improved microwave antenna feed, this combination reduc

55

The Deep Space Network as a Scientific Instrument
the system noise temperature from the value of 1,570 K, which had been used for Ech

to about 60 K for Venus. When installed at Goldstone and brought into operation f

the Venus experiment, the Pioneer receiver was believed to be the most sensitive ope

ational receiving system in the world. At the time, nothing could be done to increa

the output of the existing S-band transmitter at Echo. However, it was operated for th

Venus experiments at its maximum power output level of 13 kW.

With this extraordinary instrument, and supported by the strong technical motivatio

of Rechtin, Victor, and Stevens, the two young JPL astronomers Duane O. Muhlema

and Richard M. Goldstein had succeeded where two other distinguished scientific ins

tutions, Lincoln Laboratory and Jodrell Bank, which had conducted similar experimen

on Venus, had not.

Between 10 March and 10 May 1961, some 238 hours of scientific data were recor

ed during radar experiments conducted almost daily.

So began the DSN association with planetary radar.

Soon after the Venus radar experiment, Muhleman left JPL for Harvard, and Rechti

Victor, and Stevens turned their attention to the rapidly evolving Network and its su

port for the NASA planetary spacecraft missions. Goldstein, however, continued his clo

association with the Goldstone radar and its further development for many years. 

The first Venus radar experiment had been conducted amid growing concern at JP

about the need for two operational antennas at Goldstone to support the rapidly expan

ing lunar and planetary programs, which would need tracking support from the DSI

Added to this concern was the urgent need for an antenna which could be dedicat

to research and development activities for the engineering side of the DSIF. The Ech

antenna, being of the Azimuth/Elevation (Az-El) type, was not entirely suitable for trac

ing planetary spacecraft where horizon-to-horizon passes at a constant declination we

generally required. It was therefore decided to build a second, 26-m polar-mount ante

na at the Echo site and to move the existing Az-El antenna to a new site at Goldston

where it would be used principally for engineering development for the Network an

incidentally, for planetary radar. The second operational antenna was completed in Ma

and in a monumental feat of transportation, the 26-m Az-El antenna and its pedest

were moved as a complete unit six kilometers across the desert to a new site to 

named, obviously, Venus, in June 1962.

552

Uplink-Downlink: A History of the Deep Space Networ
As the new polar-mount antenna at Echo prepared to support the Mariner 2 flight 

Venus in August 1962, as part of the operational Network, the Az-El antenna w

refurbished at the new Venus site and resumed Venus observations as a research an

development station. 

The 1961 Venus radar had been a bistatic radar, that is, it used two antennas, one f

transmitting (Echo) and another for receiving (Pioneer). The 1962 Venus radar was 

monostatic radar using a single antenna (the former Echo antenna) for both transm

ting and receiving. This required the addition of a high-power/low-loss duplexer 

accommodate both the transmitting and receiving functions on the one antenna. Th

transmitter could be operated in a continuous-wave (CW) mode, an amplitude mod

lation (AM) mode, or a keyed (on/off) mode. A CW receiver and an AM receiv

provided open-loop or closed-loop reception for any transmitter mode. Signal level an

power spectra data were obtained using the open-loop receive configurations, while th

Earth-Venus velocity and Earth-Venus range data were obtained using the closed-loo

configurations. Several other changes were made to the Doppler and range systems 

accommodate the various modes of operation.58

A functional block diagram of the 1962 Venus radar is shown in Figure 8-10.

With this powerful new instrument, Goldstein and others continued further successf

radar observations of Venus during the 1962 and 1964 conjunctions and made the fir

detections of Mars and Mercury in 1963. 

Despite these scientific successes, however, the radar depended for its continued ex

tence on the research and development program which the DSN maintained to suppo

its operational Network. It benefited from the development work that the DSN carri

out under its Advanced Systems Development Program but was never formally esta

lished and funded as a NASA program in its own right. Because much of the technolo

required for a planetary radar was the same as that required for deep space commun

cations, the Goldstone radar received, in its early years, a great deal of support from th

DSN research and development teams. For them it offered a less critical environme

in which new technology could be evaluated before being adapted to meet the (m

sion) critical needs of the operational Network. There were many areas in which th

commonality of technology was used to the mutual advantage of the Goldstone rad

and the DSN research and development programs. These areas include: 

• very high-power transmitters,

• very low-noise microwave amplifiers,

55

The Deep Space Network as a Scientific Instrument
554

Uplink-Downlink: A History of the Deep Space Networ

Figure 8-10. Functional block diagram of the Venus radar, 1962.

ANTENNA OPTICS

RIGHT

CIRCULAR

LEFT

CIRCULAR

DUPLEXING

SWITCH

DC POWER

LOW-NOISE

AMPLIFIERS

2388-Mc

SWITCH

POWER AMPLIFIER

12.5 kW

2388-Mc

STABILIZED

EXCITER MODULATOR

CONTINUOUS WAVE

RECEIVER

PROGRAMMED

LOCAL

OSCILLATOR

AMPLITUDE

MODULATION

RECEIVER

DIGITAL-TO-ANALOG

CONVERTER AND TIME

SYNCHRONIZATION

DIGITAL-TO-ANALOG

CONVERTER AND TIME

SYNCHRONIZATION

SELECTOR

MANUAL TRACK

USING

ANTENNA OPTICS

MONITOR

RECORDING

DATA

RECORDING

ANGLES, DOPPLER, RANGE,

SIGNAL CHARACTERISTICS

EQUIPMENT

PERFORMANCE

SERVO DRIVE

AND

DIGITAL READOUT

CASSEGRAIN FEED

POLARIZATION *

RIGHT

CIRCULAR TRANSMIT

LEFT

CIRCULAR RECEIVE

* NORMAL POLARIZATION

OTHER POLARIZATIONS AVAILABLE FOR EXPERIMENTAL PURPOSESRIGHT CIRCULAR TRANSMIT, RIGHT CIRCULAR RECEIVELEFT CIRCULAR TRANSMIT, LEFT CIRCULAR RECEIVELEFT CIRCULAR TRANSMIT, RIGHT CIRCULAR RECEIVELINEAR TRANSMIT, ROTATABLE LINEAR RECEIVE

Az-El ANGLE

DATA TORECORDING

DIGITAL-TO-ANALOG

CONVERTER AND TIME

SYNCHRONIZATION

FREQUENCY

REFERENCE

MODULATING SIGNAL

FROM AM RECEIVER

OPEN-LOOP SPECTRAL ANALYSIS

CLOSED-LOOP DOPPLER DATAOPEN-LOOP SIGNAL LEVEL AND SPECTRAL ANALYSISCLOSED-LOOP RANGE DATAMODULATING SIGNAL TO TRANSMITTER

DIGITAL DOPPLER

DATA COMPUTEDFROM EPHEMERS

DIGITAL RANGE DATA

COMPUTED FROM EPHEMERS

DIGITAL RANGE DATA

COMPUTED FROM EPHEMERS
• high-efficiency microwave antenna feed systems,

• advanced ranging/Doppler systems,

• data acquisition and signal processing, and

• planetary ephemeris prediction.

In addition to providing a realistic demonstration or test bed for new technology in th

DSN, the Goldstone radar, under the guidance of R. M. Goldstein, continued to pr

duce good scientific data and to develop a presence in scientific literature.

Under this arrangement, the Goldstone radar developed rapidly. A Rubidium Frequen

Standard and improved closed-loop ranging system were added in 1962. High-pow

transmitter development for the Network led to a 100-kW S-band transmitter for th

radar in 1963. Continuing improvement in antenna feed systems and low-noise amp

fiers gave the radar a system noise temperature of 35 kelvin in 1964. Signal processin

and ranging improved again in 1966 with the addition of a 9-channel correlator an

narrower and more stable range gate. 

With these improvements, the capability of the radar was extended to include plane

at greater distances from Earth. Mars, Mercury, and even Jupiter were soon detecte

and scientifically significant observations were reported.59 Venus was revisited in 196

and its rotation and large bright surface features were observed.60

Within those first few years, half of the planets in the solar system were probed by th

Goldstone radar.

The Goldstone radar, like all other science in the DSN, was affected in a major way b

the availability of the first DSN 64-m antenna at Goldstone in 1966. Goldstein lost n

time in taking advantage of the ten-fold increase in capability provided by the 64-

antenna, compared with the 26-m antenna he had used previously at the Venus site.

The rationale for the DSN adoption of the 64-m Az-El antenna design as the secon

generation of large antennas for the Network has been discussed in earlier chapte

While none of the rationale was concerned with the application of the antenna for pla

etary radar, the same argument applied insofar as the application of radar technology 

Network problems was concerned. What was good for the radar was (in most case

good for the Network. So the radar program continued on the 64-m antenna on th

same basis as before, with two very significant exceptions. First, the radar had to com

pete with the flight projects for observing time on the antenna. The second exceptio

was that all the radar-related experimental hardware and software had to be complete

55

The Deep Space Network as a Scientific Instrument
separate from the tightly controlled operational equipment used to support the inflig

missions. Time on the antenna generally had to be justified on the grounds of relevan

of the radar data to one or more of the current missions. To keep the radar equipme

separate from the operational systems, it was located in a suitable area of the antenn

pedestal structure, with entirely separate interfaces with the antenna itself. A separa

antenna feed cone, which could be illuminated by the subreflector when needed, w

allocated to radar and other research and development activity. This arrangement remain

substantially unchanged through the life of the radar reviewed here and is still in u

today. The new 64-m antenna site became the Mars site, and in due course the rad

became the Goldstone Solar System Radar (GSSR).

Using the new Mars antenna and its enhanced radar capability, which now includ

range-Doppler mapping, Goldstein and others observed Venus again during the 196

conjunction. They discovered more distinct rugged sections of surface terrain and stu

ied a region named Beta from earlier observations in more detail. 

In June 1968, the Goldstone radar detected Icarus, its first of many Earth-crossin

asteroids. It was difficult to detect a target of such small size. Fortunately, a develo

mental 450-kW S-band transmitter was then available at the Venus site, and this, togeth

with the Mars antenna in the bistatic mode for receiving, brought the reflected sign

above the detection threshold. The bistatic arrangement also circumvented the pro

lem of rapid changeover from transmit to receive states necessitated by the short tim

interval between transmission and reception of the reflected signal from close-range ta

gets like asteroids. 

The results of the observations of Icarus were the first (Goldstone) radar work publish

in the distinguished journal for planetary science, Icarus, which subsequently becam

the primary publication for planetary radar research.61

In 1970, the first of an ambitious series of joint programs with the Lincoln Laborator

Haystack antenna was carried out. It was estimated that with Haystack as the tran

mitting antenna and Mars as the receiving antenna, a very significant increase (up 

ten times) over the capability of either one could be achieved. An X-band maser tun

to the frequency of the Haystack radar transmitter was installed on the Mars antenn

and, after several frustrating delays due to 64-m-antenna scheduling problems, Goldston

receivers made a successful detection of the Jupiter satellites Ganymede and Callisto 

May and June 1970. The gaseous structure of Jupiter prevented the return of a detectab

signal from the planet itself.

556

Uplink-Downlink: A History of the Deep Space Networ
By 1969, the 400-kW S-band capability had been installed at the Mars site and w

used for further studies of the Alpha and Beta regions of Venus. In December 197

and again in January 1973, Goldstein and Morris detected the rings of Saturn with th

powerful new capability. The returned signals were unexpectedly strong, 5 to 10 tim

stronger than those received from Venus and Mercury. This surprising result trigger

an upsurge of interest in Saturn rings amongst astronomers and led to many and va

ied interpretations of the data.62

In August 1974, Richard Goldstein and George Morris succeeded in detecting Ganyme

on six occasions with the Mars radar alone, using its 400-kW S-band transmitter an

35-K receiving system. They interpreted their results to indicate a considerable degr

of roughness on the surface, possibly due to rocky material from meteorites embedd

in a matrix of ice.

Progress on the development of a high-power X-band transmitter for the Goldston

radar was reported by C. P. Wiggins63 in 1972. Operation at X-band would provide a

increase of 6.5 dB in antenna gain, resulting in a reduction in observation time by 

factor of 20. At the same time, the wider bandwidth of an X-band system would pe

mit the use of faster range codes for more precise range measurement. The radar transmitt

receiver, microwave components and the antenna feed were to be assembled into a ne

Cassegrain cone that would be mounted in the Research and Development (R&D) po

tion of the tricone on the Mars antenna. Excessive transmission losses would be avoid

by operating the transmitter close to the antenna feed. The transmitter would opera

at a center frequency of 8.495 MHz and be fixed tuned with a bandwidth of 50 MH

at the -1 dB points. It would consist of two 250-kW klystrons with a four-port hybr

to combine the two outputs into one waveguide port, and it would use the high-vo

age power supply and cooling system that normally powered the operational DSN S-ban

400-kW transmitter. 

This new development was justified on the basis of a study of the rings of Saturn as 

possible hazard to spacecraft navigation for the future Voyager missions to Jupiter an

Saturn. The first opportunity to probe the Saturnian system with radar would start 

December 1974, just three years before the two Voyagers were scheduled to launch an

six years before the first Voyager would arrive at Saturn.

Despite delays caused by unavailability of 64-m antenna time for installation work, th

X-band transmitter was completed and began observations on Saturn’s rings in Decemb

1974. The data from these observations confirmed the previous Goldstone results an

also more recent results from the Arecibo radar, regarding the high radar cross-sectio

55

The Deep Space Network as a Scientific Instrument
(reflectivity for radar signals) and the high linear and polarization ratios. Again, the inte

pretation of these results was the subject of a great deal of discussion in the scientif

community. Various models, from a thick cloud consisting of irregularly shaped, ce

timeter-size chunks of water-ice to large, meter-size metallic boulders covered with fro

were proposed. Voyager opted for the former model and continued planning its m

sion. The subject was not closed, however, and the rings of Saturn were observed aga

in 1977, 1978, and 1979.

The question of the composition and structure of the Saturn rings and the role of rad

astronomy in addressing it led Andrew Butrica to observe, very astutely, 

The case of Saturn’s rings resulted in radar astronomers contributing to planetary science, in contrast to their studies of the Galilean moons. Those studies

. . . had been limited to epistemological studies, namely, what caused the Galilean

moons’ strange radar signatures? Radar contributed to Saturn science, on the

other hand, by focussing less on such questions of radar technique and more

on scientific questions, such as the size of the ring particles and the number

and thickness of the ring layers. Although the solution of technical problems

was a prerequisite for any radar astronomy problem solving, the lack of obvious relevance to planetary science was a serious matter; the ability to solve

scientific problems, especially those relating to NASA space missions, was the

basis on which scientists judged the value of radar astronomy and on which

funding decisions were made.64

As subsequent events would show, the issue raised by Butrica in the preceding par

graph—justification, and its effect on funding for the continued operation of the Goldsto

radar—would be a growing concern for the DSN in the years ahead.

However, in the immediate future, the Viking mission to Mars was concerned with th

selection of a suitable landing site for its two Landers. Surface roughness and slope we

key parameters in the landing site selection process, and these were ideally suited 

radar observation. Although Mars observations had been made in 1969, they cover

latitudes that were of no interest to Viking, and in any case, the results were too noi

to be of much use for landing site selection. New data was needed, particularly of th

Syrtis Major and Sinus Meridiana regions which included potential Viking landing site

The radar group at JPL had expanded by then and included Richard R. Green, Howa

C. Rumsey, George S. Downs, Paul E. Reichley, and Ray F. Jurgens, in addition 

Goldstein and Morris. Using funds provided by the Viking Project office, members 

558

Uplink-Downlink: A History of the Deep Space Networ
this team used the Goldstone radar to make X-band observations of the Syrtis Maj

and Sinus Meridiana regions from October 1975 through April 1976.65 The extent 

which the Goldstone results, along with similar observations from the Arecibo and Stanfo

radars, influenced the final landing site decision remains an open question. It is cle

however, that the radar data, presented in the form of degrees of rms slope, was n

readily understood by the scientists making the decision, who lacked an adequate unde

standing of the new radar techniques. For them, the high-resolution images from th

Viking Orbiter were a more persuasive source of information. 

Whatever the role of radar in the final decision, the site that was eventually select

proved to be very satisfactory, as was shown by the subsequent landings and the Lande

long period of successful operation on the Mars surface. 

Following the radar detection of Icarus in 1968, interest in asteroids increased among

radar astronomers, at first in simply detecting them, but later in inferring their shap

and nature of the surface material. In 1972, Goldstein observed 1685 Toro, and 

1975 the asteroid 433 Eros was probed at S-band and X-band and with left an

right circular polarization. These data allowed Goldstein and Jurgens to characteri

the size, shape, and surface properties of the asteroid with better resolution than ha

been possible to that time. This was an important step toward future progress in th

techniques of asteroid characterization based on dual-frequency, dual-polarization, an

radar data. Although it was not apparent at the time, asteroid research was event

ally to become the principal activity for the Goldstone radar, but that situation l

twenty years into the future.

Continuing the support for the Voyager mission now approaching Jupiter, Goldstein an

Green observed Ganymede and Callisto in December 1977 at X-band, and with le

and right circular polarization. The unexpected radar signature they obtained confirm

earlier Arecibo results but led to an interpretation of the surface of the satellites whi

were at variance with the photographic images returned from Voyager during the act

al Jupiter Encounter. The reason for this apparent contradiction remained unclear. Sever

theories were advanced to account for it, some of which involved a better understan

ing of the radar properties of planetary surfaces rather than more general scientific issue

The questions of scientific worth versus technological value were again pertinent to th

continued interest of NASA in the radar. 

For the next few years, the Goldstone radar received only sporadic use. The resources 

the DSN were oversubscribed with flight projects like Viking Orbiters 1 and 2, Vikin

Lander 1, Helios 1 and 2, Pioneers 6 through 9, and Voyagers 1 and 2. These missions we

55

The Deep Space Network as a Scientific Instrument
reluctant to relinquish 64-m antenna time at Goldstone for radar experiments, no matt

how scientifically interesting they claimed to be. Furthermore, Rechtin, Victor, and Goldste

had by then moved on, and within the DSN there was no longer the strong constitue

cy for radar support as there had been in former years. Budget constraints in the TD

Office eliminated funding for maintenance of the Goldstone radar equipment, so that ev

when astronomers were able to obtain observing time on the antenna, precious time w

often taken up with simply getting the radar to work. At NASA Headquarters, OTD

was the source of funding for the DSN. ODTA declared that all further planetary rad

support by the DSN should be conducted in response to a formal requirement from OSS

in the same manner as the DSN responded to OSSA requirements for tracking and da

acquisition support for flight missions. The necessary NASA Management Instruction w

issued (NMI 8430.1B) to this effect, and the TDA Office at JPL developed the low

level documentation to cover radar requirements and support agreements.

While these changes were slowly evolving, and despite the difficulties of working wi

the radar, Jurgens and his team were able to refurbish the radar in time to make the

first successful radar observation of a comet, IRAS-Araki-Alcock, in May 1982. Attemp

to observe comets on subsequent occasions were not successful until 1996, when J. K

Harmon and others succeeded in detecting Comet Hyakutake in 1996.

In 1984, in response to persistent efforts by Jurgens and Downs, the NASA Office 

Space Science made funds available for the procurement of a new Digital Equipme

Corporation VAX 11/780 computer to be used for data acquisition and processing fun

tions in the Goldstone radar. The computer formed the heart of a new High Spe

Data Acquisition System (HSDAS), whose primary mode of operation was the colle

tion and processing of radar data. It supported CW and ranging radar experimen

which would be required for the terrestrial and outer planet targets planned in the futu

years. These included Mars, Mercury, Venus, asteroids, comets, Galilean satellites, an

the rings of Saturn. 

As a subsystem of the planetary radar, the HSDAS collected the 15-MHz bandwid

RF signal from the radar receivers and performed all of the necessary data rate com

pression (filtering, phase correction, and correlation) functions necessary to get the rad

data on to a general-purpose computer for further processing and analysis. These fun

tions had been performed in the past by an ever-increasing array of hardware devic

that were inadequate for the high-bandwidth radar experiments planned for the futur

The extreme flexibility designed into the HSDAS and the ability to control it from sim

ple high-level programming languages made it a useful tool for many other, nonrad

purposes as well, such as radio astronomy, advanced receiver development, real-tim

560

Uplink-Downlink: A History of the Deep Space Networ
arraying, and SETI. It was installed with the other radar equipment in the DSS 1

antenna pedestal area and, with periodic improvements, served the radar well for th

next decade. An overall block diagram of the High Speed Data Acquisition System 

shown in Figure 8-11.66

In 1983, Peter T. Lyman, the Assistant Laboratory Director for Tracking and Da

Acquisition, placed responsibility for direction of the Goldstone radar in the TDA Scien

Office under the management of Nicholas A. Renzetti. It was Renzetti’s goal to convin

NASA’s Office of Space Science that the Goldstone radar warranted funding on the ba

of its value to NASA as a scientific instrument. With the support of Steven J. Ostr

who had recently arrived at JPL from Cornell, where he had worked with Arecibo rad

they redefined the Goldstone Solar System Radar (GSSR) in terms of a “scientific instr

ment” on which planetary radar science could be performed. This closely paralleled th

approach that had been used successfully to support radio astronomy, SETI, and crust

dynamics in the DSN. To implement this approach, and to provide an interface betwe

the radar and the scientific community, Renzetti also created the concept of “Friend 

the Radar,” a position filled first by Thomas W. Thompson. Martin A. Slade filled th

position in 1988. 

It was expected that requests for GSSR support would be received from OSS and fun

ing to meet the requirements would come from OTDA, just as was done with the flig

56

The Deep Space Network as a Scientific Instrument

Figure 8-11. High Speed Data Acquisition System for the Goldstone Radar, 1984.

FROM

BASEBAND

FROM

RECEIVERS

TO 

TRANSMITTER

TRANSMITTER

DRIVER

PN

GENERATORS

FPS

ARRAY

PROCESSOR

CORRELATOR

ASSEMBLY

IF

PROCESSOR

GENERAL PURPOSE

DATA ACQUISITION

HARDWARE

VAX 11/780

COMPUTER
projects. But this never happened, and despite the endeavors of Renzetti and others 

sell the idea of the GSSR as a national resource for planetary radar research, the k

issue of funding for the GSSR remained unsolved. 

In 1987, the Director of the Space Science and Instruments Office at JPL obtained 

modest level of funding from NASA for planetary radar research and appointed Ost

to manage its disposition in support of an observing program with the GSSR. Und

Ostro’s influence, science finally supplanted technology as the justification for the GSSR

existence, and excellence in its unique field of science became its goal.

Then, as had happened frequently in the past, events external to its own program ove

took planetary radar and resulted in a very significant advance in the capabilities of th

instrument. Over the period October 1987 through May 1988, the DSS 14 antenn

was upgraded and extended from 64 meters to 70 meters to meet the requirements 

the expanding planetary spacecraft program. 

Driven initially by the tracking and data acquisition requirements of the Voyager Neptun

Encounter, described in an earlier chapter, the 64-meter to 70-meter upgrade was 

Network-wide implementation task which had been several years in the planning. DS

14 was the last of the three antennas to be completed. 

As Butrica viewed it, “the Voyager upgrade had a profound impact on the practice 

Radar Astronomy at JPL; it provided the GSSR with the sensitivity needed to carry o

research on a whole new set of targets (and to begin solving new sets of problems). N

only did the GSSR gain the ability to undertake asteroid research but, when linked 

the Very Large Array in New Mexico, it became a new radar research tool.”

The immediate benefit to the GSSR is illustrated in Figure 8-12 and shows the rel

tive sensitivity of the 64-m and 70-m antennas for radar observations at X-band as 

function of declination. The improvement of about 2 dB corresponds to the increa

in antenna gain resulting from the increase in antenna diameter and other relat

improvements.67

The figure also shows the improvement that would have resulted from replacing th

400-kW transmitter with a super-high-power, 1,000-kW transmitter. This latter initiati

was promoted by Renzetti in 1989 as part of a further upgrade to the GSSR, which inclu

ed changes to the radar’s transmit/receive system to improve its capability for trackin

asteroids. Although the megawatt radar transmitter proposal was not approved, the aste

oid modification to the radar feed system was eventually implemented. From 1992 throug

562

Uplink-Downlink: A History of the Deep Space Networ
1993, a low-noise waveguide switch was developed and installed. This device enabled tran

mit and receive through the same microwave horn, with a switch-over time of two second

It thereby obviated the cumbersome sub-reflector switching procedure, which, with a switc

over time of 25 to 30 seconds, had always limited the GSSR ability to observe targe

close to Earth. In 1996, the waveguide switch was superseded by an elegant arrangeme

of two movable mirrors which, mounted external to the feed horns, did not compromi

either the radiated power or the sensitivity of the low-noise receiver.

By a fortuitous circumstance (for planetary radar), the so-called Voyager upgrade in th

DSN included the addition, at DSN expense, of low-noise X-band amplifiers to all 2

of the 25-meter antennas of the Very Large Array radio telescope operated by the NRA

in New Mexico. Long affiliated with activities in the DSN, the VLA had participat

in the Voyager Neptune Encounter as an element of a Goldstone-VLA array for reco

ery of downlink telemetry. The Voyager images of Saturn’s moon Titan revealed a bod

covered with an opaque layer of cloud, and the instruments suggested there might be 

global ocean of liquid ethane beneath the cloud cover. 

Prior to the encounter, Caltech professor Duane O. Muhleman had suggested that th

new VLA capability might be used effectively in the bistatic mode with GSSR for pla

etary radar to further study Titan, with the objective of characterizing its surface featur

and composition. Previous attempts to probe Titan with either the VLA or the GSS

had not been successful, but the enhanced sensitivity of both combined offered the be

chance of success.

56

The Deep Space Network as a Scientific Instrument

Figure 8-12. Relative sensitivity for the Goldstone Radar Antenna.

1.25

1.00

0.75

0.50

0.25

0 80 S 40 S 0 40 N 80 N

DECLINATION, deg

MEGAWATT GOLDSTONE

λ = 3.5 cm

1000 kW

70 meters

GOLDSTONE (1988)

λ = 3.5 cm

350 kW

70 meters

GOLDSTONE (1987)

λ = 3.5 cm

350 kW

64 meters

RELATIVE SINGLE-DATE SNR
As a first demonstration of the GSSR/VLA bistatic system, and with GSSR transm

ting and VLA receiving, the rings of Saturn were successfully observed in early 198

The following year, Muhleman, Butler, and Slade observed Titan for the first time o

the nights of 3–6 June. The echoes from Titan were similar to those that had bee

received from the Galilean satellites and suggested an icy surface, but more observatio

were needed. Further observations were made jointly with VLA in 1992 and again 

1993.68 The results of these experiments, although somewhat at variance with curre

models of the Titan surface, were of great interest to the Cassini Saturn mission pla

ners and were factored into the design for the Huygens Probe radar, scheduled to descen

to the surface of Titan in 2004.

With minor changes to the VLA configuration, and using different polarizations, th

VLA-Goldstone bistatic arrangement was used by the same experimenters to obser

Mars, first in 1988 and again, several times, during the 1992–93 opposition, and 

further investigate the presence of ice on the surface of Mercury in 1991.69

Amongst planetary radar astronomers, interest in Venus had diminished during the la

1980s for a number of reasons, some of them having to do with availability of resourc

and the attraction of more distant targets. With the launch of Magellan and the extrao

dinary success of its orbital radar mission in 1990, scientific investigation of Venus b

planetary radar essentially came to an end. There were, however, several investigatio

of anomalous radar signatures from Venus conducted in subsequent years. 

Asteroids

The Voyager upgrade to the Goldstone radar antenna, along with the addition of th

new HSDAS, gave the GSSR the sensitivity and resolution needed for the detection 

asteroids. The arrival of Steven J. Ostro provided the TDA Science Office with the exp

rience and motivation required to engage in this new field of research in a major wa

An opportunity to combine the new capability with the addition of Ostro’s experien

in a way that would change the course of the GSSR forever was not long in coming

Three-dimensional modeling of asteroid shapes based on range-Doppler radar imag

was still a relatively new technique when the Earth-crossing asteroid 4179 Toutatis w

discovered in January 1989. Toutatis was predicted to pass very close (9.4 lunar d

tances) to Earth on 8 December 1992. This would make it an ideal target for range-Doppl

imaging with the GSSR. Ostro proposed an elaborate observing program to Renze

that involved the GSSR, Arecibo, VLA, and the new DSS 13 BWG antenna workin

as an interferometer with the GSSR. The outcome would be the highest resolution thre

564

Uplink-Downlink: A History of the Deep Space Networ
dimensional images of an Earth-crossing asteroid ever produced. Renzetti accepted, an

the planning went forward.

Observations were carried out at the various sites over the period from 27 Novemb

through 19 December 1992, and a good data return was obtained.70 Although the su

sequent reconstruction of the images was complicated by the slow tumbling rotation

state of the asteroid, they revealed the general shape and surface topography of Touta

at the highest resolution ever obtained of an asteroid. Typical images from this expe

ment are shown in Figure 8-13 and reveal the presence of several craters on the tw

(apparently connected) components of the irregularly shaped main body of the asteroi

56

The Deep Space Network as a Scientific Instrument

Figure 8-13. Goldstone Solar System Radar images of Asteroid Toutatis, 1992.
Using similar techniques, Ostro and Hudson successfully observed the next Earth-cros

ing asteroid, 1620 Geographos, in 1994 and produced equally impressive imaging 

the asteroid body. In 1995, observations of 6489 Golevka included delay-Doppler ima

ing, GSSR-VLA astrometry, and the first intercontinental planetary radar experimen

from Goldstone to Russia and Japan. Less than 600 meters across, Golevka was th

smallest solar system object imaged to that time.71

As scientific interest in radar observation of asteroids increased, it gave rise a heighten

awareness of the hazards posed by possible Earth encounters with asteroids and rais

questions of how such threats might be handled in the best interests of the public. Th

role that the GSSR might play in continued evolution of this intriguing subject is d

cussed in the relevant scientific literature.72

Radar Astrometry

Astrometry is a branch of astronomy that deals with the measurement of the position

motions, and distances of planets, stars, and other celestial bodies, including asteroid

In recent times, when Ostro and others employed radar techniques to study and pr

dict the motions of asteroids, the term “radar astrometry” was coined to describe th

aspect of radar astronomy.

Thus, data generated by the GSSR were used, not only for science data for imaging an

surface characterization experiments, but also to refine the orbits of Earth-crossing aste

oids. This extension of the GSSR capability was proposed originally by Jurgens an

carried forward by Ostro, who enlisted the support of two of JPL’s orbit determinatio

specialists, Donald K. Yeomans and Paul W. Chodas. Supported by this powerful grou

of experts, radar astrometry gained prominence in the period 1990–92 using data fro

the GSSR and the Arecibo radars.73 Together with like advances in radar imaging, rad

data were recognized by the International Astronomical Union (IAU) as a data sour

in its circulars to announce the discovery and orbit of newly discovered asteroids. 

It seemed most likely that postdiscovery IAU circulars for new asteroids in the ne

future would be composed of computer files containing high-resolution video images 

the objects and highly precise ephemerides, based on data taken by the GSSR an

Arecibo planetary radars. 

566

Uplink-Downlink: A History of the Deep Space Networ
Renaissance

The renaissance of the Goldstone Solar System Radar dates from about the early 1990

By that time, the radar was no longer perceived primarily as a test bed for new DS

technology, but was recognized in its own right as a scientific instrument for solar sy

tem research. The remarkable success in the first detection of the Earth-crossing asteroi

did much to popularize the new approach to planetary radar. Over the period fro

1993 to 1997, most GSSR research was conducted under the aegis of NASA’s missio

to the solar system. Research topics lay within the scope of the Solar System Exploratio

or Structure and Evolution of the Universe programs as shown in the table below. 

NASA Theme: Structure and Evolution of the Universe

GSSR Experiment:

Mercury Tests of Gravitational Theories—

Ongoing experiments

NASA Theme: Formation and Dynamics of Earth-like Planets

GSSR Experiments:

Mercury Surface Properties—

Ongoing analysis of new and existing data

Mercury Polar Studies—

X-band full-disk imaging planned for 1998/1999

Venus Surface Properties—

Observations planned for 1998/1999

Venus Geophysics—

Observations planned for 1998/1999

Mars Surface Properties—

Observations planned for 1999 Mars opposition

Mars Polar Studies—

Observations planned for 1999 Mars opposition

Mars Geophysics—

Analysis of existing topographic maps in progress

Galilean satellites—

No new observations currently planned

NASA Theme: Mission to Planet Earth

GSSR Experiments:

Earth Stratospheric Studies—

No new observations currently planned

Lunar Polar Observations—

Data from 1997 observations being analyzed

56

The Deep Space Network as a Scientific Instrument
NASA Theme: Mars Exploration Support

GSSR Experiment:

Mars Landing Site Certification—

Radar data aided landing site certification for 1997 

Mars Pathfinder landing74

Observations in 1999 will aid future 2001 landings

NASA Theme: Building Blocks and Our Chemical Origins

GSSR Experiments:

Asteroids, Imaging and Orbit Refinement—

Several asteroid observations planned each year

Radar Data Crucial for Orbit Determination of Near-Earth 

Asteroids

Titan Surface Properties—

Bistatic observations with VLA planned for

October 1998 to aid Cassini Huygens-Probe 

mission

Comet studies—

Comet Hyakutake observed in 199675

Observations to continue as opportunities arise 

The outcome of all this activity was a plethora of publications in the scientific liter

ture. In the ten-year period from 1988 to 1997, nearly 100 papers based on data fro

the GSSR were published in highly respected journals such as Science, Icarus, Bullet

of the American Astronomical Society, and Lunar and Planetary Science. The productiv

ty of the Goldstone Radar, in terms of yearly scientific publications for the most rece

ten- year period, is shown in Figure 8-14. 

The data clearly show the revival of interest in radar astronomy following the Voyag

upgrade and the start of the asteroid detection program. The data also suggest that th

level of scientific interest, when constrained by the amount of antenna time availab

for radar observations, results in the publication of 10 to 12 papers per year. It do

not lead to any conclusion regarding the scientific value of the papers so produced.76

As we have seen, the constant efforts of a relatively small group of dedicated scientis

produced a steady stream of scientific knowledge throughout the lifespan of the Goldston

radar reviewed here. Sometimes the stream slowed to a trickle and sometimes it was 

full flood, but it never dried up. The number of publications that resulted from the

efforts attests to the productivity of the radar. 

568

Uplink-Downlink: A History of the Deep Space Networ
Significant Events

To better appreciate the overall scope of the work done with the radar over the first 3

years of its active life, the reader may wish to consult the following table of significa

events in the scientific life of the radar.

Significant Events in the DSN Planetary Radar Program

1961 Venus First detection, determined value for AU to accuracy of 500 km

refined ephemerides

1962 Venus Determined slow retrograde motion

1963 Mars First detection, measured albedo vs. longitude at 13 degrees la

itude

1963 Mercury First detection, measured albedo and range

1963 Jupiter Statistically significant detection, not repeated

1964 Venus Discovered large bright surface features

56

The Deep Space Network as a Scientific Instrument

Figure 8-14. Goldstone Radar astronomy publications, 1988–97.

DSN Radar Astronomy Publications 1988–1997

18

16

14

12

10

8

6

4

2

0 1988 1990 1992 1994 1996 1998

Number Published
1965 Mars Measured albedo and roughness vs. longitude, Ma IV came

directed to image Trivium Charontis, a very bright smooth rad

target

1966 Venus Located of a number of new surface features, rotation found 

be approx. 243.0 days 

1967 Venus Accurate range measurements led to improved knowledge of Ven

orbit and radius, and also AU

1968 Icarus First detection of asteroid, verified ephemeris and estimated si

and roughness

1969 Venus Range measurements, large map with highest resolution, nort

south ambiguity resolved

1969 Mars Determined accurate (±0.2 km) altitude profile of equatorial regio

1969 Mercury Surface features detected (not Venus-like)

1970 Mars Detailed surface mapping

1970 Jupiter Observed satellites Ganymede, Callisto for Voyager with Haysta

in the bistatic mode

1971 Mars Detailed surface mapping

1972 Toro Asteroid 1685 Toro detected

1973 Saturn Saturn rings observed

1974 Ganymede Observed surface of Ganymede

1975 Mars Surface roughness studies for Viking Lander site selection

1975 Eros Asteroid 433 Eros detected

1977 Ganymede Ganymede observed right and left circular polarization returns

570

Uplink-Downlink: A History of the Deep Space Networ
1978 Saturn Saturn rings observed

1979 Saturn Saturn rings observed

1982 Comet Comet IRAS-Araki Alcock detected

1987 Jupiter Determined polarization ratios and radar cross sections of Galilea

satellites, noted strange radar signatures

1989 Saturn Observed satellite Titan for Cassini with Haystack in bistatic mo

1991 Mercury Observed Mercury with Haystack in bistatic mode

1991 Earth Observed Earth orbital debris

1992 Mars Observed Mars with VLA in bistatic mode

1992 Asteroid Observed first Earth-Crossing Asteroid (ECA) 4179 Toutatis wi

DSS 13 in bistatic mode

1993 Mars Observed Mars with VLA in bistatic mode

1993 Mercury Full-disk radar images, detection of ice at North Polar region

1994 Asteroid Three-dimensional modeling of Earth-Crossing asteroid 162

Geographos

1995 Mars Pathfinder landing site characterization

1996 Comet Successful observation of Comet Hyakutake

1997 Moon Search for ice in shadowed areas of the Polar Regions

57

The Deep Space Network as a Scientific Instrument
Endnotes

1. M. S. Reid, R. C. Clauss, D. A. Bathker, and C. T. Stelzried, “Low-Noise Microwa

Receiving Systems in a Worldwide Network of Large Antennas,” Proceedings of t

IEEE, vol. 61, no. 9 (September 1973), p. 1330–35.

2. Andrew J. Butrica, To See the Unseen: A History of Planetary Radar, The NAS

History Series, NASA SP-4218 (Washington, DC: NASA History Office, 1996). 

3. M. J. Klein, oral interview with author, 9 April 1998.

4. N. A. Renzetti, “Oral History,” J. Alonso, 17 April 1992.

5. N. A. Renzetti and A. L. Berman, “The Deep Space Network as an Instrument f

Radio Science Research,” JPL Publication 80-93 (15 February 1981).

6. S. W. Asmar and N. A. Renzetti, “The Deep Space Network as an Instrument f

Radio Science Research,” JPL Publication 80-93, Rev. 1. (15 April 1993).

7. C. T. Stelzreid, “A Faraday Rotation Measurement of a 13cm Signal in the Sol

Corona,” JPL Technical Report TR 32-1401 (1970), p. 83.

8. R. Woo, and R. Schwenn, “Comparison of Doppler Scintillation and In-Si

Spacecraft Plasma Measurements of Interplanetary Disturbances,” Journal 

Geophysical Research 96 (1991): 21227–44.

9. A. Kliore, D. L. Cain, and T. W. Hamilton, “Determination of Some Physic

Properties of the Atmosphere of Mars from Changes in the Doppler Signal of 

Spacecraft on an Earth-Occultation Trajectory,” JPL Technical Report TR 32-67

(1964).

10. G. L. Tyler, “Radio Propagation Experiments in the Outer Solar System wi

Voyager,” Proceedings of the IEEE, vol. 75, no. 10 (1987).

11. J. D. Anderson, P. B. Exposito, W. Martin, C. L. Thornton, and D. O. Muhlema

“Experimental Test of General Relativity Using Time-Delay Data from Mariner 

and Mariner 7,” Astrophysical Journal 200 (1975): 221–33.

572

Uplink-Downlink: A History of the Deep Space Networ
12. F. B. Estabrook and H. D. Walhquist, “Response of Doppler Spacecraft Tracking 

Gravitational Radiation,” General Relativity and Gravitation 6 (1975): 439–47.

13. N. A. Renzetti et al., “The Deep Space Network—An Instrument for Rad

Astronomy Research,” JPL Publication 82-68, Rev. 1 (1 September 1988). 

14. K. W. Linnes, “Radio Science Support,” JPL Technical Report TR 32-1526, Vol. II

The Deep Space Network, Progress Report, March-April 1971 (15 June 1971

46–51.

15. M. J. Batty, D. L. Jauncey, S. Gulkis, and M. J. Yerbury, “The Tidbinbil

Interferometer,” PR 42-58, May-June 1980 (15 August 1980): 6–8.

16. M. J. Batty, D. L. Jauncey, P. T. Rayner, and S. Gulkis, “Accurate Radio Positio

with the Tidbinbilla Interferometer,” TDA Progress Report PR 42-58, May-Jun

1980 (15 August 1980), pp. 1–5. 

17. G. S. Levy et al., “Orbiting Very Long baseline Interferometer Demonstration Usin

the Tracking and Data Relay Satellite System,” Proceedings of Internation

Astronomical Union Symposium, no. 110, VLBI and Compact Radio Sourc

(Bologna, Italy, 27 June–1 July 1983), pp. 405–06.

18. T. B. H. Kuiper to N. R. Haynes, “On the Role of Radio Astronomy in the DSN

internal memorandum, TBK 94-007, 6 February 1994.

19. T. B. H. Kuiper and M. R. Wick, “Radio Astronomy Observations Program

Detailed Mission Requirements,” Jet Propulsion Laboratory, JPL Document No. D

12940, DSN 870-348 (1 February 1996).

20. T. B. H. Kuiper to D. J. Mudgway, “Significant Advances in Radio Astronom

Using the DSN,” personal communication, August 1999.

21. J. S. Gubbay et al., “Trans-Pacific Interferometer Measurements at 2300 MHz

Nature: 222, 730.

22. G. S. Downs et al., “Average Pulsar Energies at Centimeter Wavelengths,” Natu

222 (1969): 1257.

57

The Deep Space Network as a Scientific Instrument
23. P. E. Reichley and G. S. Downs, “Observed Decrease in the Period of Pulsar PS

0833-43,” Nature 222 (1969): 229.

24. B. G. Clark et al., “Variations in the Fine Structure of Quasars 3C279 and 3C273

Bulletin of the American Astronomical Society 3 (1971): 383.

25. R. L. Carpenter et al., “Search for Small-scope Anisotropy in the 2.7 Cosm

Background Radiation at a Wavelength of 3.56 Centimeters,” Astrophysical Journ

182 (1973): L61.

26. M. J. Batty et al., “Tidbinbilla Two-element Interferometer,” Astronomical Journ

87 (1982): 938.

27. J. S. Ulvestad, C. D. Edwards, and R. Linfield, “Very Long Baseline Interferomet

Using a Radio Telescope in Earth Orbit,” TDA Progress Report PR 42-88, Octobe

December 1988 (15 February 1986): 1–10.

28. R. Linfield et al., “VLBI Observations of Three Quasars Using an Earth-orbitin

Radio Telescope,” Bulletin of the American Astronomical Society 18 (1986): 993.

29. K. M. Desai et al., “First Speckle Hologram of the Interstellar Plasma,” Astrophysic

Journal 393, no. 2 (10 July 1992): L75–L78.

30. S. J. Tingay et al., “The Subparsec-Scale Structure and Evolution of Centaurus A

The Nearest Active Radio Galaxy,” Astronomical Journal 115, issue 3 (March 1998

960–74. 

31. T. Velusamy, T. B. H. Kuiper, and W. D. Langer, “CCS Observations of th

Protostellar Envelope of B335,” Astrophysical Journal 451 (October 1995): L75.

32. T. B. H. Kuiper, W. D. Langer, and T. Velusamy, “Evolutionary Status of the Pr

protostellar Core L1498,” Astrophysical Journal 468 (September 1996): 761.

33. C. R. Gwinn et al., “Size of the Vela Pulsar’s Radio Emission Region: 50

Kilometers,” Astrophysical Journal 483 (July 1997): L53.

34. J. C. Guirado et al., “Astrometric Detection of a Low-Mass Companion Orbitin

the Star AB Doradus,” Astrophysical Journal 490 (December 1997): 835.

574

Uplink-Downlink: A History of the Deep Space Networ
35. R. E. Edelson and G. S. Levy, “The Search for Extraterrestrial Intelligenc

Telecommunications Technology,” TDA Progress Report PR 42-57, March-Ap

1980 (15 June 1980), pp. 1–8.

36. A. L. Berman, “The SETI Observational Plan,” TDA Progress Report PR 42-5

March-April 1980 (15 June 1980), pp. 9–15.

37. B. K. Levitt, “SETI Pulse Detection Algorithm: Analysis of False Alarm Rates

TDA Progress Report PR 42-74, April-June 1983 (15 August 1983), pp. 149–5

S. Gulkis and E. T. Olsen, “Gain Stability Measurements at S-band and X-band

TDA Progress Report PR 42-74, April-June 1983 (15 August 1983), pp. 159–6

B. Crow, “SETI Downconverter,” TDA Progress Report PR 42-67, Novembe

December 1981 (15 February 1982), pp. 1–5; E. T. Olsen and A. Lokshin, “Th

SETI Interpreter Program—A Software Package for the SETI Field Tests,” TD

Progress Report PR 42-74, April-June 1983 (15 August 1983), pp. 169–82.

38. B. Crow, A. Lokshin, M. Marina, and L. Ching, “SETI Radio Spectru

Surveillance System,” TDA Progress Report PR 42-82, April-June 1985 (15 Augu

1985), pp. 173–84.

39. S. Gulkis, M. J. Klein, E. T. Olsen, R. B. Crow, R. M. Gosline, G. S. Downs, M. 

Quirk, A. Lokshin, and J. Solomon, “Objectives and First Results of the NAS

SETI Sky Survey Field Tests at Goldstone,” TDA Progress Report PR 42-86, Apr

June 1986 (15 August 1986), pp. 284–93.

40. J. Solomon, W. Lawton, M. P. Quirk, and E. T. Olsen, “A Signal Detection Strate

for the SETI All Sky Survey,” TDA Progress Report PR 42-83, July-September 198

(15 November 1985), pp. 191–201; M. P. Quirk, H. S. Wilk, and M. J. Grimm, “

Wide-Band, High Resolution Spectrum Analyzer,” TDA Progress Report PR 42-8

July-September 1985 (15 November 1985), pp. 180–90.

41. M. J. Klein, S. Gulkis, E. T. Olsen, and N. A. Renzetti, “The NASA SETI Sk

Survey: Recent Developments,” TDA Progress Report PR 42-98, April-June 198

(15 August 1989), pp. 218-2-26.

42. G. R. Coulter, M. J. Klein, P. R. Backus, and J. D. Rummel, “Searching f

Intelligent Life in the Universe: NASA’s High Resolution Microwave Survey,” 

Sjoerd L. Bonting, ed., Advances in Space Biology and Medicine, Vol. 4 (Greenwic

Connecticut: JAI Press, 1992), pp. 189–224.

57

The Deep Space Network as a Scientific Instrument
43. K. M. Ong, P. F. MacDoran, J. B. Thomas, H. F. Fliegel, L. J. Skjerve, D. 

Spitzmesser, P. D. Batelaan, S. R. Paine, and M. G. Newsted, “A Demonstration 

Radio Interferometric Surveying Using DSS 14 and the Project Aries Transportab

Antenna,” DSN Progress Report PR 42-26, January-February 1975 (15 Ap

1975), pp. 41–53.

44. D. L. Brun, S. C. Wu, E. H. Thom, F. D. McLaughlin, and B. M. Sweetser, “Orio

Mobile Unit Design,” TDA Progress Report PR 42-60, September-October 198

(December 1980), pp. 6–32.

45. C. G. Koscielski, “Mojave Base Station Implementation,” TDA Progress Report P

42-78, April-June 1984 (15 August 1984), pp. 216–24.

46. J. M. Davidson and D. W. Trask, “Utilization of Mobile VLBI for Geodet

Measurements,” TDA Progress Report PR 42-80, October-December 1984 (1

February 1985), pp. 248–66.

47. L. A. Buennagel, P. F. MacDoran, R. E. Neilan, D. J. Spitzmesser, and L. E. Youn

“Satellite Emission Range Inferred Earth Survey (SERIES) Project: Final Report o

Research and Development Phase, 1979 to 1983, JPL Publication 84-16 (Pasaden

California: JPL, 1984).

48. J. M. Davidson, C. L. Thornton, S. A. Stephens, S. C. Wu, S. M. Lichten, J. 

Border, O. J. Sovers, T. H. Dixon, and B. G. Williams, “Demonstration of th

Fiducial Concept Using Data From the March 1985 GPS Field Test,” TDA Progre

Report PR 42-86 (April-June 1985), pp. 301–06.

49. J. M. Davidson, C. L. Thornton, T. H. Dixon, C. J. Vegos, L. E. Young, and T. 

Yunck, “The March 1985 Demonstration of the Fiducial Network Concept for GP

Geodesy: A Preliminary Report,” TDA Progress Report PR 42-85, January-Marc

1986 (15 May 1986), pp. 212–18.

50. G. Lanyi, “Total Ionospheric Content Calibration Using Series GPS Satellite Data

TDA Progress Report PR 42-85, January-March 1986 (15 May 1986), pp. 1–12

51. GPS Flight Demonstration on Topex, JPL proposal, July 1984.

52. DSCC Media Calibration Subsystem, DMD 1987–1992, Functional Desig

Review, November 1986.

576

Uplink-Downlink: A History of the Deep Space Networ
53. Catherine L. Thornton, interview with Douglas J. Mudgway (April 1998). 

54. W. K. Victor and R. S. Stevens, “Exploration of Venus by Radar,” Science 13

(1961): 46.

55. Andrew J. Butrica, To See the Unseen: A History of Planetary Radar, The NAS

History Series, NASA SP-4218 (Washington, DC: NASA History Office, 1996).

56. M. H. Brockman, L. R. Malling, and H. R. Buchanan, “Venus Radar Experiment

JPL Research Summary No. 36-8, Vol. 1 (February-April 1961), pp. 65–73. 

57. W. Higa, “A Maser System for Radar Astronomy,” JPL Technical Report TR 32-10

(1 March 1961).

58. R. M. Goldstein, R. Stevens, and W. K. Victor, “Goldstone Observatory Report f

October-December 1962,” JPL Technical Report TR 32-396 (1 March 1965).

59. R. M. Goldstein, “Mars: Radar Observations,” Science CL (24 December 1965

1715–17.

60. R. M. Goldstein and R. L. Carpenter, “Rotation of Venus: Period Estimated fro

Radar Measurement,” Science CXXIX (8 March 1963), pp. 910–11.

61. R. M. Goldstein, “Radar Observations of Icarus,” Icarus no. 10 (1969): 430–31.

62. R. M. Goldstein and G. A. Morris, “Radar Observations of the Rings of Saturn

Icarus no. 20 (1973): 260–62.

63. C. P. Wiggins, “X-band Radar Development,” JPL Technical Report TR 32-152

Vol. XII, September-October 1972 (15 December 1972), pp. 19–21.

64. See endnote 2, p. 215.

65. G. S. Downs, R. R. Green, and P. E. Reichley, “Radar Studies of the Martian Surfa

at Centimeter Wavelengths: The 1975 Opposition,” Icarus no. 33 (1978): 

441–53.

57

The Deep Space Network as a Scientific Instrument
66. L. J. Deutsch, R. F. Jurgens, and S. S. Brokl, “The Goldstone Research an

Development High-Speed Data Acquisition System,” TDA Progress Report PR 4

77, January-March 1984 (15 May 1984), pp. 87–96.

67. N. A. Renzetti, T. W. Thompson, and M. A. Slade, “Relative Planetary Rad

Sensitivities: Arecibo and Goldstone,” TDA Progress Report PR 42-94, April-Jun

1988 (15 August 1988), pp. 287–93.

68. B. J. Butler, D. O. Muhleman, and M. A. Slade, “Results From 1992 and 199

VLA/Goldstone 3.5 cm Radar Data,” Bulletin of the American Astronomical Socie

25 (1993): 1040.

69. M. A. Slade, B. J. Butler, and D. O. Muhleman, “Mercury Goldstone-VLA Rada

Part I,” Bulletin of the American Astronomical Society 23 (1991): 1197.

70. S. J. Ostro et al., “Radar Imaging of Asteroid 4179 Toutatis,” Bulletin of t

American Astronomical Society 25 (1993): 1126.

71. S. J. Ostro, “Goldstone Radar Research of Near-Earth Asteroids,” DSN Technolog

and Science Program News issue 7 (February 1997): 13.

72. S. J. Ostro, “The Role of Ground-Based Radar in Near-Earth Object Haza

Identification and Mitigation,” in T. Gehrels and M. S. Matthews, eds., Hazards D

to Comets and Asteroids (Tucson, Arizona: University of Arizona Press, 1994), p

259–82.

73. D. K. Yeomans et al., “Asteroid and Comet Orbits Using Radar Data,” Astronomic

Journal 103 (1992): 303–17. 

74. M. A. Slade, R. F. Jurgens, A. F. C. Haldeman, and D. L. Mitchell, “Haza

Evaluation for the Mars Pathfinder Prime Landing Site from Synthesis of Rad

Ranging and Continuous Wave Observations During the 1995 Mars Opposition

Bulletin of the American Astronomical Society 27, no. 3 (1995): 1103.

75. J. K. Harmon et al., “Radar Detection of the Nucleus and Coma of Com

Hyakutake,” (C/1996 B2), Science 278 (1997): 1921–24.

578

Uplink-Downlink: A History of the Deep Space Networ
76. Radar astronomy online Web sites: A comprehensive listing of publishe

scientific work based on all aspects of GSSR observations is available 

http://wireless.jpl.nasa.gov/RADAR/.

77. Papers dealing with radar observations of asteroids are listed at http://echo.jpl.nasa.go

publications/pubs.html.

57

The Deep Space Network as a Scientific Instrument
Chapter 

The Deep Space Network 

as an Organization in Change

581
IN THE BEGINNING (1958 TO 1963) 

Background

Following the ARPA decision to launch several lunar probes by the end of 1958 usin

the Army JUNO-II launch vehicle, the Army turned to its long-time contractor, JP

for the payloads and the tracking and data acquisition facilities required for its portio

of the new Pioneer Program.1

The flight paths of the lunar probes required a tracking station at Cape Canaveral 

cover the launch phase, another in the vicinity of Puerto Rico for the near-Earth phas

and a deep space station in the general vicinity of JPL to track the probe on its way 

the Moon. Time was short. There were only eight months to select a site, build a

antenna, and set up the requisite receivers, recorders, and communication circuit

Fortunately, the Army owned a considerable amount of property in the Mojave Deser

and it was on this property at Goldstone Dry Lake, about 100 air miles from L

Angeles, that a suitable site for building the deep space antenna was found. 

Construction of the site began at Goldstone in June 1958; assembly of the antenn

commenced in August; and by December, the antenna, together with electronics, receiver

and communications, was complete. Pioneer 3 was launched on 6 December 1958. Th

station, appropriately named Pioneer, was the first station of what was to become th

Deep Space Instrumentation Facility (DSIF), and eventually the Deep Space Netwo

(DSN) described in earlier chapters.

As these events began to unfold in 1958, the engineering organization within JPL reflec

ed the technologies that had been appropriate to the missile guidance and telemet

support provided as a contractor to the U.S. Army. The three principal engineerin

departments were Aerodynamics and Propellants, Design and Power Plants, and Guidan

and Electronics. The Guidance and Electronics Department, headed by Robert J. Park

consisted of three Technical Divisions: Guidance Analysis, led by Clarence R. Gate

Guidance Development, led by Walker E. Giberson; and Guidance Research, led b

Eberhardt Rechtin. Rechtin’s Guidance Research Division consisted of an Electroni

Research Section under Walter K. Victor and a Guidance Techniques Research Sectio

led by Robertson Stevens.2 Design and implementation of the Pioneer DSIF station w

carried out under the technical management of engineers from these two sections, wi

overall responsibility shared by Rechtin, Victor, and Stevens. 

582

Uplink-Downlink: A History of the Deep Space Networ
In addition to its work for the Army, JPL also supported a substantial aerodynami

research facility known as the Southern California Cooperative Wind Tunnel. This fac

ity was funded and used, on a cooperative basis, by the many aerospace compani

flourishing in the southern California region at that time. Although the Wind Tunn

was in no way associated with the DSIF, its Chief of Facilities and Mechanical Equipme

would soon play a prominent role in the future history of the DSN. His name w

William H. Bayley.

A mechanical engineering graduate (1952) from the University of Southern Californ

(USC) in Los Angeles, Bill Bayley worked on facilities engineering for the Lockhee

Aircraft Corporation in Burbank, California, before coming to JPL in 1956 to manag

the facilities of the southern California Cooperative Wind Tunnel. At that time, and f

several years afterward, this major research facility reflected JPL’s association with Caltec

and aeronautical research.

After JPL’s transfer to NASA, Rechtin’s network of tracking stations, communication

and data-processing systems, as well as the staff needed to run it, expanded rapidly. H

needed help. The addition of an assistant to interact with NASA on issues of staff an

budget and to deal with financial and administrative matters at JPL allowed Rechtin 

address the more technical issues associated with the future world network. He turne

to Bill Bayley, a perfect choice as it turned out, and made him General Manager 

1960. When Rechtin left JPL in 1967, Bayley assumed Rechtin’s position as Assista

Laboratory Director for Tracking and Data Acquisition, a position he held with di

tinction until he retired in 1980. During his term of office, the Deep Space Netwo

developed into a major NASA facility of 26-m, 34-m, and 64-m antennas in three coun

tries around the globe. That achievement was due, in no small measure, to his skill 

dealing with both NASA Headquarters and JPL and his ability to optimize the rel

tionship between them in the best interests of the DSN. 

A pleasant man to talk to and a gentle man to deal with, both at work and outside th

work environment, Bill Bayley was popular with his colleagues at JPL and NAS

Headquarters, as well as his counterparts at the government agencies in Spain, Australi

and South Africa, on whom NASA depended for support of its tracking stations in tho

countries. His quiet sense of humor—he was a master of the “bon mot” and “doub

entendre”—served to enhance his connectivity with the people he met. Bill Bayley intr

duced “all hands” meetings to the DSN as a way of bringing top management in

direct contact with all members of the organization for a frank and open discussion 

problems, policies, and procedures. Such meetings, led by Bayley himself, were alwa

58

The Deep Space Network as an Organization in Change
held away from the normal workplace to create a less formal and more productive atmo

phere for the free expression of ideas and opinions.

He was a devotee of healthy living and exercise, so it was ironic that Bayley’s untime

death in 1981 was due to a heart-related problem.

The Rechtin Years

In 1958, while the Pioneer antenna was being rushed to completion at Goldstone 

meet the deadline for the first Pioneer Lunar Probe launch in December, momento

events were occurring elsewhere in the U.S. space effort. Later that year, Congress passe

the National Aeronautics and Space Act to create the National Aeronautics and Spa

Administration (NASA). President Eisenhower immediately signed the new Act into law

and NASA began operating under the leadership of its first Administrator, T. Kei

Glennan, on 1 October 1958. The transfer of JPL from the Army to NASA followe

almost immediately. Instead of working under a U.S. Army contract, JPL now worke

under a NASA contract. NASA inherited not only JPL’s experienced personnel and i

facilities, including Goldstone, but also JPL’s vision of a worldwide tracking network f

deep space probes.3 NASA’s plans for JPL were in keeping with this vision, and the

was no interruption to the work in progress as a result of this essentially political chang

However, within NASA and JPL, the change raised serious questions regarding the st

tus of JPL. NASA wanted to operate JPL like other Agency Centers, rather than, as JP

desired, an outside contractor managed by Caltech. Describing this situation, historia

Clayton Koppes wrote, “Insider or outsider. Vast amounts of time and energy would b

consumed in resolving the question of insider or outsider throughout the next decade.

Despite these internal disturbances, essential work moved rapidly forward.

When the new NASA Headquarters organization first came into being, responsibili

for NASA-wide tracking and data acquisition services and facilities rested in Abe Silverstein

Office of Space Flight Development. Within that office, the position of Assistant Direct

for Space Flight Operations was filled initially by Edmond C. Buckley. 

In this capacity, Buckley interacted directly with JPL on all matters related to NAS

policy, guidelines, and budget for the original construction and operation of the DSI

Referring to Buckley’s early association with the DSN, historian Cargill Hall said, “

graduate of Rensselaer Polytechnic Institute, personable and articulate, he brought 

NASA many years of [NACA] experience in the development of the Wallops Islan

584

Uplink-Downlink: A History of the Deep Space Networ
Launch Range, where he had been responsible for the development of tracking an

instrumentation associated with free flight research.”

Fortunately for the fledgling DSN, Ed Buckley at NASA Headquarters and Eb Recht

at JPL enjoyed a great deal of mutual respect and worked well together to further the

common goal, the establishment of a worldwide network for NASA. Observed Carg

Hall, “No major disagreements (between NASA and JPL) marred the planning and cr

ation of the Deep Space Network.”

Responsibility for tracking and data acquisition in the NASA Office of Space Flig

Development at this time is shown in Figure 9-1.

Within a very short time of its transfer to NASA, the organization of JPL was restru

tured to better meet its new responsibilities in the changing world. No longer was i

primary business that of missiles and rockets and the tracking and data acquisition tech

nology to support them as a contractor to the U.S. Army, but lunar and planeta

58

The Deep Space Network as an Organization in Change

Figure 9-1. NASA Office of Space Flight Development, 1959–61.

OFFICE OF THE ADMINISTRATOR

ADMINISTRATOR

T. KEITH GLENNAN

DEPUTY ADMINISTRATOR H. L. DRYDEN

OFFICE OF SPACE FLIGHT DEVELOPMENT

DIRECTOR

A. SILVERSTEIN

ASSISTANT DIRECTOR SPACE FLIGHT OPERATIONS

E. C. BUCKLEY

SR SCIENTIFIC

REPRESENTATIVE

IN AUSTRALIA

E. P. HARTMAN

CHIEF

ADVANCED DEVELOPMENT

F. B. SMITH

CHIEF

OPERATIONS

G. M. TRUSZYNSKI

EXECUTIVE ASSISTANT

PLANS AND BUDGETS

M. E. GREENSPON

TRACKING

SYSTEMS

C. R. MORRISON

TELEMETRY

SYSTEMS

W. L. IKARD

DATA AND

COMPUTING

SYSTEMS

J. K. STERRETT

NETWORK

OPERATIONS

AND FACILITIES

H. R. BROCKETT

INTERAGENCY

OPERATIONS

N. POZINSKY

COMMUNICATIONS

OPERATIONS AND

FREQUENCY

ALLOCATIONS

P. A. PRICE

FLIGHT MISSION

OPERATIONS

V. W. HAMMOND

R. D. BRISKMAN
spacecraft and the technology to support them as a contractor to NASA. Seven ne

technical divisions and six administrative divisions were created to deal with JPL’s ne

responsibilities in NASA’s expanding Lunar and Planetary Program. All seven technic

divisions were directly responsible to JPL Director William H. Pickering, while the admin

istrative divisions reported to the Assistant Laboratory Director (ALD) of the Busine

Administration Office, Victor C. Larsen. Amongst the technical divisions, th

Telecommunications Division (Division 33), with Rechtin named as Chief and Bayl

as Assistant Chief, contained the essential technological expertise that was to become th

foundation stone of the emerging worldwide DSIF. In addition to Chief of th

Telecommunications Division, Rechtin was also designated as Program Director for th

DSIF, an indication of the growing importance of the DSIF in the JPL organizatio

planning, and budget processes. 

The Telecommunications Division, under Rechtin’s leadership, comprised four section

to provide the state-of-the-art technical and operational resources needed to transfor

the DSIF from a single antenna in California to a worldwide network with tracking st

tions on three continents. The organization of the DSIF during this period, 1961–6

is shown in Figure 9-2.

Working within this structure, Nicholas A. Renzetti led the engineering, implement

tion, and operations activity supported by an aggressive and very successful research an

586

Uplink-Downlink: A History of the Deep Space Networ

Figure 9-2. Telecommunications Division at JPL, 1961–62.

COMMUNICATIONS

RESEARCH

W. K. VICTOR

COMMUNICATIONS

ELEMENTS RESEARCH

R. STEVENS

COMMUNICATION

SYSTEM

DEVELOPMENT

J. KOUKOL

COMMUNICATIONS ENGINEERING

AND OPERATIONS

N. A. RENZETTI

JPL Resident Engineers S. Africa, P. Jones

Australia, R. Fahenstock

TECH. STAFF

P. Goodwin

W. Spaulding

P. Tardani

TRACKING DATA ANALYSIS

J. P. Fearey

DAT SYSTEMS

ENGINEERING

C. W. Johnson

SYSTEM TEST

AND OPERATIONS R. K. Mallis

SYSTEMS

ENGINEERING

R. Z. Toukdarian

GOLDSTONE

OPERATIONS

W. Larkin

TELECOMMUNICATIONS DIVISION

E. RECHTIN,

CHIEF AND PROGRAM DIRECTOR

W. H. BAYLEY, ASST. CHIEF
development program led by Victor, Stevens, and Koukol. In 1961 and 1962, the tot

engineering and technical staff for both functions totaled about 200 to 250 person

with a budget of 15 to 20 million dollars. Three years later, reflecting the demands 

an expanding network, the staff had increased to 300 to 400, while the budget ha

increased to 50 to 60 million dollars. In addition to developing the DSIF, these sam

technical resources were heavily engaged in supporting the first of the NASA lunar an

planetary missions, the Rangers and Mariners. 

Although the Mariner 2 mission to Venus was very successful and attracted a great de

of scientific attention, the first five Ranger missions were not. In the aftermath of 

NASA inquiry into problems with the Ranger program, JPL restructured some par

of its organization that were associated with the lunar and planetary programs.5 The

changes would have a far-reaching effect on the relationship between the organizatio

of the DSIF and that of the flight projects. The JPL structure which followed is show

in Figure 9-3.

Of most significance to the future development of the DSIF was the creation of tw

new offices headed by assistant laboratory directors who reported directly to the JP

director. These were a Lunar and Planetary (Flight) Projects Office headed by Robe

J. Parks and a DSIF Office headed by Rechtin. These two offices would provide th

programmatic direction for 1) the Mariner, Surveyor, and remaining Ranger mission

and 2) the DSIF, respectively. Technical and administrative support would be pr

vided by the seven technical divisions and the six administrative divisions. Althoug

initially the Technical Divisions were in direct line to the JPL director, an addition

al Office for Technical Divisions was established within the next year with Fred H

Felberg as ALD. This office coordinated and directed the activities of all seven tech

nical divisions at the program level. With the exception of moving Victor to th

Chief position, with Joseph F. Koukol as deputy, the Telecommunications Divisio

remained intact.

JPL had arrived at an organization within which the DSIF, later to become the DSN

would coexist with the flight projects and the technical divisions for the next seve

al decades. As we shall see, fairly major modifications were made from time to tim

but with these basic offices in place, the DSN moved rapidly forward to meet th

demands for tracking and data acquisition support for the expanding NASA Lun

and Planetary program.

Equally important to the evolution of the DSN in these early years were the chang

taking place in the newly formed NASA organization. As William R. Corliss explaine

58

The Deep Space Network as an Organization in Change
Rather unexpectedly in the early 1960s, the tracking and data acquisition

function was assuming more and more importance in NASA’s budget and,

consequently, in its organizational structure. Space flight turned out to be

not just all launch rockets and spacecraft, it depended very heavily upon

ground facilities for testing, launching, and, of course, tracking and communication. The early literature of space flight does not foresee these

developments at all. Management practicalities soon forced NASA to recog588

Uplink-Downlink: A History of the Deep Space Networ

Figure 9-3. JPL organization, 1964.

JET PROPULSION LABORATORY W. H. PICKERING, DIRECTOR

B. SPARKS, DEPUTY

SERVICES, SUPPORT AND

STUDY GROUPS FOR

DIRECTORS OFFICE

ASSISTANT DIRECTORS FOR

RESEARCH, DEVELOPMENT, AND ADMINISTRATION

E. RECHTIN ASSISTANT DIRECTOR DEEP SPACE INSTRUMENTATION FACILITY

R. J. PARKS

ASSISTANT DIRECTOR

LUNAR AND PLANETARY

PROJECTS OFFICE

FLIGHT PROJECTS Ranger

Surveyor

Mariner

OTHER TECHNICAL DIVISIONS

DIVISION 33

TELECOMMUNICATIONS

W. K. VICTOR, CHIEF

DIVISION 31

SYSTEMS

C. R. GATES, CHIEF

Program Engineering

W. Shipley

System Test and

Operations

J. McGee

Systems Analysis

T. W. Hamilton

Space Flight Operations

M. S. Johnson

System Design

W. Downhower

Launch Vehicle Systems

H. Magraf

Communications

Engineering and Operations R. K. Mallis

Spacecraft Telemetry and

Command

R. B. Harker

Communications

Engineering and Operations R. K. Mallis

Communications Systems

Research

M. F. Easterling

Spacecraft Radio

R. P. Mathison

R.F. Systems Development

L. W. Randolph

Communications

Elements Research

R. Stevens
nize the importance of tracking and data acquisition by placing this function on a par with space science, manned space flight, etc. On 1 November

1961, a new Office of Tracking and Data Acquisition (OTDA) was created

at NASA Headquarters. Edmond C. Buckley, who had been in charge of

Space Flight Operations, was named director of the new office. In effect, the

entire tracking and data acquisition function was elevated a notch in the

NASA Headquarters hierarchy.

The new Office of Tracking and Data Acquisition in NASA Headquarters at the en

of 1961 is shown in Figure 9-4.

The organization remained in this form until OTDA moved up another step within th

NASA hierarchy when the position of Director, previously filled by Ed Buckley, was el

vated to Associate Administrator status in 1966. Buckley held that position until h

retired in 1968. He was replaced by Gerald M. Truszynski.

58

The Deep Space Network as an Organization in Change

Figure 9-4. NASA organization for the Office of Tracking and Data Acquisition, 1961.

OFFICE OF THE ADMINISTRATOR

ADMINISTRATOR

JAMES E. WEBB

DEPUTY ADMINISTRATOR H. L. DRYDEN

OFFICE OF TRACKING AND

DATA ACQUISITION

DIRECTOR

E. C. BUCKLEY

DEPUTY DIRECTOR

G. M. TRUSZYNSKI

NETWORK OPERATIONS AND FACILITIES

H. R. BROCKETT

DOD COORDINATION

F. B. BRYANT

PROGRAM COORDINATION AND RESOURCES

AND MANAGEMENT

T. V. LUCAS

PROGRAM SUPPORT AND ADVANCED SYSTEMS

C. R. MORRISON

FACILITIES AND STATION

IMPLEMENTATION

N. POZINSKY

COMMUNICATION AND

FREQUENCY

MANAGEMENT

P. A. PRICE

NETWORK

OPERATIONS

J. C. BAVELY

ADVANCED

SYSTEMS

R. R. STEPHENS
Truszynski, a native of Jersey City, New Jersey, came to NASA Headquarters in 196

from Edwards Air Force Base in California, where he had been chief of the instru

mentation division involved in developing tracking systems for jet- and rocket-powere

aircraft. A year later, he was named deputy in the Office of Tracking and Da

Acquisition and eventually followed Edmond Buckley to become the second Associa

Administrator of that office in 1968. In that position, he was responsible, at th

NASA Headquarters level, for the planning, development, and operation of glob

tracking networks, including the DSN, facilities for NASA Communication

(NASCOM), and data acquisition and processing for all NASA spaceflight program

His term of office covered the Mariner and Viking Eras and paralleled the Bayle

period in the Tracking and Data Acquisition Office at JPL. This was a period 

enormous growth and change in the DSN. It was, perhaps, the period when th

Network passed from youth to maturity. Gerry Truszynski and Bill Bayley worke

well together as heads of the teams at Headquarters and JPL that brought abo

those changes. 

In addition to his involvement with NASA’s Deep Space Network, Truszynski played 

major role in the provision of tracking, data, and supporting services for the Apollo 

and Apollo 11 lunar missions.

Although the DSIF Office at JPL was not made an official program office until 196

interactions between it and OTDA had been conducted as if it were. This situatio

changed in October 1963, when Rechtin’s title was elevated from Program Director f

the DSIF to Assistant Laboratory Director for Tracking and Data Acquisition (ALD/TDA

and the former DSIF Office became the official TDA Program Office, a title it retaine

for the next thirty years. At last, the organization at JPL paralleled that at NAS

Headquarters, as far at TDA was concerned. There remained one more event to fini

the story of the formation of the modern DSN. That final event occurred in Decemb

1963 with the formal establishment of the Deep Space Network by the JPL directo

The historic interoffice Memo 218 that made the announcement, dated 24 Decemb

1963, is reproduced in Figure 9-5.

In addition to the former DSIF, the tracking stations at Goldstone, California; Woomer

Australia; Johannesburg, South Africa; and Cape Canaveral, Florida, the official DS

included the intersite communications now called the Ground Communications Facili

(GCF) and the mission-independent portions of the new Space Flight Operations Facili

(SFOF) at JPL. 

590

Uplink-Downlink: A History of the Deep Space Networ
59

The Deep Space Network as an Organization in Change

Figure 9-5. The Deep Space Network established, December 1963.
The events just described were of fundamental importance to the shaping the DSN du

ing its formative stages. These and subsequent events are summarized in the table below

Top-Level Management of the DSN at JPL, 1960–97

Year Event or Deputy/Program JPL Director

Head of DSN: Title Manager 

1958 NASA established Pickering

(October); 

JPL moves to NASA

(December)

1960–62 Rechtin: Chief, Div. 331 Bayley Pickering

and DSIF Director 

(January 1961)

1963 Rechtin: ALD2/DSIF Bayley Pickering

(March)

Victor: Chief, Div. 33,

DSN established 

(December)

1964 Rechtin: ALD/TDA3 Bayley Pickering

1967 Bayley: ALD/TDA Victor Pickering

1980 Lyman: ALD/TDA Johnson4 Murray

1987 Dumas: ALD/TDA Johnson Allen

1992 Haynes: ALD/TDA Westmoreland Stone

1994 TMOD5 Established Stone

1996 Westmoreland: Director, Coffin4 Stone

TMOD (June)

1997 Squibb: Director, Coffin Stone

TMOD (June)

1 Telecommunications Division.

2 Assistant Laboratory Director.

3 Tracking and Data Acquisition; changed to Telecommunications and Data Acquisition in 1982 to avo

confusion with NASA’s new Space Network using the Tracking and Data Relay Satellite System (TDRS

planned for operation the following year.

4 The title of Deputy was superseded by Program Manager in 1980 and again in 1996.

5 Telecommunications and Mission Operations Directorate.

592

Uplink-Downlink: A History of the Deep Space Networ
After the DSN was formally established at the end of 1963, the basic organization

involving the DSN at NASA Headquarters and at JPL changed very little until 199

except for personnel and some vacillation concerning responsibility for the SFOF. With

the DSN organization, however, many changes were made in the interest of improvin

working relationships with OTDA and with the Flight Projects. The growth and deve

opment of the DSN organization during this thirty-year period, 1964–94, is the subje

of our next discussion. 

59

The Deep Space Network as an Organization in Change
THE FORMATIVE YEARS (1964 TO 1994)

A DSN Manager for Flight Projects

Within a few short months of the formalization of the DSN, further changes were mad

to the organizational structure under which the DSN operated at JPL. A JPL organiz

tion chart from 1964 showing the relative positions of the TDA and flight projec

offices, including their supporting technical divisions, is reproduced in Figure 9-6.

All of the technical divisions were directed by a single ALD, Fred Felberg. A technic

staff element was added to the TDA Office, and Richard K. Mallis took over th

Communications Engineering and Operations Section formerly managed by Renzet

Renzetti moved to a Technical Staff position in the TDA Office as the first DSN Manag

for the Ranger, Mariner, and Apollo missions. He was soon joined by DSN Manage

for the Lunar Orbiter, Surveyor, and Pioneer missions. In the Systems Division, Thom

S. Bilbo replaced Marshall S. Johnson as Chief of Space Flight Operations. Thus, Mal

and Bilbo were independently responsible to their division managers for the operatio

of the SFOF and the DSN, respectively. They received technical support from other se

tions within the same divisions, but in a programmatic sense, their authority derive

from completely separate sources. The SFOF traced its funding and program directio

via the Lunar and Planetary Projects Office at JPL, to OSSA at NASA Headquarter

while the DSN traced its funding and program direction, via the Tracking and Da

Acquisition Office at JPL, to OTDA at NASA Headquarters.

The appearance of the DSN Manager function in the TDA organization needs som

explanation at this point, since it became a key factor in determining the future wor

ing relationships between the DSN and its client users, the flight projects.

As an inevitable consequence of the creation of separate offices at NASA Headquarte

for flight projects and tracking and data acquisition, a separate system of accountabi

ty for the resources required by the one to support the other came into being. Base

somewhat on a long-existing system used at the military test ranges for receiving an

responding to range users’ requirements for instrumentation to cover their tests, the sy

tem was introduced to the DSN by a formal NASA Management Instruction (NM

2310.1) dated March 1965. In this system, flight project requirements for DSN trac

ing and data acquisition services were identified in a Support Instrumentatio

Requirements Document (SIRD). Upon receipt of a SIRD, the DSN would respon

with a NASA Support Plan that committed its resources as it deemed necessary to me

the requirements in the SIRD. The SIRD and NSP were formal documents signed b

594

Uplink-Downlink: A History of the Deep Space Networ
the program managers at OSSA and OTDA, respectively, and were intended to signi

approval for the expenditure of the TDA resources involved.

In earlier times, when one or two tracking stations and simple facilities for control 

flight operations were all managed more or less by a single entity, verbal agreements 

internal memos between participating groups were all that was needed to conduct mi

sions for a single JPL-managed spacecraft. No longer was that the case. By the mid-1960

59

The Deep Space Network as an Organization in Change

Figure 9-6. Organization for Tracking and Data Acquisition support at JPL, October 1964

JET PROPULSION LABORATORY

W. H. PICKERING, DIRECTOR

SERVICES, SUPPORT AND

STUDY GROUPS FOR

DIRECTOR’S OFFICE ASST. LAB. DIRECTORS FOR

RESEARCH, DEVELOPMENT

AND ADMINISTRATION

R. J. PARKS

ASST. LAB. DIR.

LUNAR AND PLANETARY

PROJECTS

F. H. FELBERG

ASST. LAB. DIR.

TECHNICAL DIVISONS

FLIGHT PROJECTS

Ranger

Surveyor

Mariner 64

Mariner 69

DIVISION 29

Project Engineering

OTHER

TECHNICAL DIVISIONS

E. RECHTIN

ASST. LAB. DIR.

TRACKING AND DATA ACQUISITION

W. H. BAYLEY

GENERAL MANAGER

DEEP SPACE NETWORK

TECHNICAL STAFF

DSN MANAGERS

Ranger, Mariner, Apollo, N. Renzetti

Lunar Orbiter, Surveyor, M. Johnson

Pioneer, J. W. Thatcher

DSN RESIDENTS;

 S. Africa, (Johannesburg)

 Spain, (Madrid)

 Australia, (Canberra, Woomera)

DIVISION 31

SYSTEMS

C. R. GATES, CHIEF

DIVISION 33

TELECOMMUNICATIONS

W. K. VICTOR, CHIEF

Systems Analysis

T. W. Hamilton

Computer Applications

F. Lesh

Space Flight Operations T. S. BilboData Systems

A. Accord

Communications Systems

Research

M. F. Easterling

Communications Engineering

and Operations

R. K. Mallis

Spacecraft Telemetry and

Command

R. B. Harker

Communications Elements

Research

R. Stevens

R.F. Systems Development

L. W. Randolph

Spacecraft Radio

R. P. Mathison
the DSN had expanded to two 26-m Networks and large 64-m antennas were und

construction. Spaceflight missions were conducted from a large, completely new facili

called the Space Flight Operations Facility (SFOF), and several major, non-JPL project

including Apollo, were demanding its services. 

To deal with this situation, Rechtin assigned a technical staff position to a DSN Manag

for each flight project. The DSN manager functioned as single point of contact betwee

his flight project and the DSN, which at that time included the SFOF, for conveyin

and negotiating requirements and commitments for tracking and data acquisition, mi

sion operations, and data-processing support. The documentation system by which the

agreements were consummated was the SIRD and NSP. In actuality, the role of th

DSN Manager extended beyond the DSN to include responsibility for negotiating su

port for his flight project from other entities such as the NASA Communications Divisio

(NASCOM) at GSFC for communications, the Air Force Eastern Test Range (AFETR

for launch support tracking coverage from land stations, Department of Defense (DOD

for ships and aircraft, the Lewis Research Center (LeRC) for launch vehicle data, an

so on. Although the DSN manager did not have an inline operational role in flig

operations, he was at all times held accountable to the flight project manager for th

performance of the DSN in support of mission operations, according to the negotiate

agreements.

The Space Flight Operations Facility

It had become apparent during the early part of the Ranger Program that the limite

facilities available at JPL for conducting flight operations and mission control would n

be adequate to support the greatly expanded space programs of the future. 

With this in mind, JPL made a recommendation to NASA for the construction of 

new building at JPL that would be entirely dedicated to accommodating the personne

equipment, and facilities needed to manage all of the elements involved in flight ope

ations on a continuous, round-the-clock basis. These elements included the DSIF, groun

communications, data processing and display, and mission control, with all the intern

communications needed to make them work together. NASA approved the recommen

dation in mid-1961. Under the aegis of the NASA Office of Space Science and Applicatio

(OSSA), construction of what was called the Space Flight Operations Facility (SFOF

began shortly afterward. The SFOF was completed in October 1963. The IBM 709

and 7040 computers and 1301 disk files were moved in immediately and began ope

ating just before the launch of the Mariner 4 mission to Mars in November 1964. Thu

596

Uplink-Downlink: A History of the Deep Space Networ
Mariner 4 was the first flight project to be supported by the new SFOF operating wi

a combination of real-time and non-real-time computing systems. 

In December 1964, however, programmatic responsibility for the SFOF was transferre

from OSSA to OTDA on the basis of the interrelated functions of mission control 

the SFOF and Network control in the DSN. This responsibility had been anticipate

in Pickering’s announcement establishing the DSN in December 1963, and it remaine

a major element of the DSN for almost the next decade.6 While the TDA Office assume

programmatic responsibility for the SFOF, its operational and technical support was pr

vided by the Space Flight Operations and Data Systems Sections of the Systems Divisio

31, in a somewhat analogous way to that in which the Telecommunications Divisio

33 supported the DSN. (See Figure 9-6.) 

The years following the transfer of the SFOF to the DSN were marked by a gre

increase in the number and complexity of the flight missions that the DSN was calle

upon to support. Many of these missions were managed by institutions other than JP

The Lunar Orbiter and Pioneer missions (and, to a lesser extent, the Surveyor and Apol

missions) were typical of this period. 

At the same time, the DSN itself was expanding. The second 26-m subnet and the L/

band conversion were completed in 1965; the first 64-m antenna became operation

in 1966; and the multi-mission concept was introduced in 1967.

Toward the end of the 1960s, improvements in communication control, data distrib

tion and display, and computer-based switching of intersite circuits were made in th

SFOF. Intersite communications were carried on high-speed and wideband data lines 

speeds of 4,800 bps and 50 kbps, respectively, by the DSN Ground Communication

Facility, which was also part of the SFOF. Paralleling the increased data-handling cap

bility of the Mark III DSN, the data-handling capability of the SFOF data processo

was also expanded by the replacement of the old IBM computers with two IBM 36

75 and two Univac 1108 machines with appropriate interface switches for flexibility an

redundancy.

While all of this development was taking place in the DSN, GCF, and SFOF, all thr

facilities were simultaneously conducting an intense program of lunar and planetary mi

sions operations. The success of all these missions attests to, amongst other things, th

adequacy of the organization under which they were performed. With the exception 

several personnel changes, notably the resignation of Rechtin and the appointment 

Bayley to replace him as ALD/TDA, the organization remained as shown in Figure 9-

59

The Deep Space Network as an Organization in Change
Nevertheless, despite the apparent suitability of the existing organization to the task 

was being called upon to perform, all was not well at the higher levels of managemen

As William Corliss explains, 

The deep space missions of the late 1960s and early 1970s brought with them

substantial increases in the SFOF’s data[-]processing load. Much of this data

processing was strictly scientific and unrelated to DSN operations. Yet, the

tracking and data acquisition function was obligated to provide for this computer time without the authority to review requirements. The flight projects

were, in essence, requesting and getting large blocks of computer time and were

neither financially nor managerially accountable for them. It was a bad managerial situation. NASA Headquarters recognized the situation and, in October

1971, Gerald Truszynski (OTDA) and John Naugle (OSS) reviewed the problem and decided to transfer the SFOF functions from OTDA back to OSSA.

In this way the responsibility for review and validation of requirements and

the associated costs of scientific data processing would be borne by the flight

projects themselves.

The change at Headquarters was immediately reflected at JPL, where responsibility f

the SFOF was moved from the TDA Office to a newly created Office of Computin

and Information Systems (OCIS). This new organization reported not to OTDA, b

to OSS. The transfer became effective in July 1972, and the organization of the tech

nical divisions at JPL which resulted from or gave rise to (depending on the point 

view) the separation of the SFOF from the DSN is shown in Figure 9-7.

The Office of Computing and Information Systems, with Allan Finerman as manage

directed the Data Systems Division, which, under the management of Glen E. Lairmor

provided technical support and operational direction for the SFOF and the GCF. 

The Telecommunications Division and Mission Analysis Division provided engineerin

development and navigation-related analysis for the independent DSN.

The TDA Office, under the ALD (Bayley), assigned a manager to each of the thr

major areas of effort in the Network for which it was responsible. Both implementatio

of new hardware and software in the Network and Network Operations functions we

carried out by Kurt Heftman, the DSN Engineering and Operations manager. Interfac

between the DSN and all flight projects for the negotiation of requirements and com

mitment of DSN resources were provided by Mission Support Manager Nicholas A

Renzetti and his staff of five DSN managers. The integration of the various elements 

598

Uplink-Downlink: A History of the Deep Space Networ
the DSN into coherent unified systems was led by John W. Thatcher. The TDA Offi

also maintained a representative at each overseas site to deal directly with local govern

ment officials on matters pertinent to the operation of the tracking stations in the

countries. Program Control (budgetary matters) were handled by Wallace P. Spauldin

Although the separation of the SFOF from the DSN may have appeared to be mere

a “paper exercise,” it was not accomplished without considerable disruption to the car

fully crafted interface agreements already in place between the DSN and the Pione

and Viking flight projects.7, 8 Schedules, interface agreements, and capabilities had bee

negotiated with various elements of the flight projects and had been formally doc

mented and approved, in accordance with current practices. These schedules, agreement

and capabilities, of course, included the SFOF as well as the DSIF. When the separ

tion took place, new interfaces between the DSN and the flight project, and the DS

and OCIS, had to be developed and documented.

59

The Deep Space Network as an Organization in Change

Figure 9-7. Organization of the technical divisions after the transfer of the SFOF to OCI

1972.

JET PROPULSION LABORATORY

DIRECTOR

W. H. PICKERING

OFFICE OF COMPUTING

AND INFORMATION

SYSTEMS

A. FINERMAN

MANAGER

ASSISTANT LABORATORY DIRECTOR

FOR TECHNICAL DIVISIONS

J. N. JAMES, MANAGER

400

ASSISTANT LABORATORY DIRECTOR

FOR TRACKING AND DATA

ACQUISITION

W. H. BAYLEY

DEPUTY ASSISTANT LAB DIRECTOR W. K. VICTOR

390

MISSION ANALYSIS

DIVISION

C. R. GATES

MANAGER

330

TELECOMMUNICATIONS DIVISION

R. STEVENS

MANAGER

910

DATA SYSTEMS DIVISION

G. E. LAIRMORE

MANAGER

GROUND

COMMUNICATIONS

FACILITY

SPACE FLIGHT

OPERATIONS FACILITY

NAVIGATION AND

ORBIT

DETERMINATION

DEEP SPACE

STATIONS

401

DSN ENGINEERING AND OPERATIONS

MANAGER, K. HEFTMAN

SYSTEMS AND PROJECT ENGINEERS

402

DSN RESIDENTS

W. E. LARKIN, AUSTRALIA

M. S. GLENN, SPAIN

R. J. FAHNESTOCK, S. AFRICA

430

DSN SYSTEMS

J. W. THATCHER

440

TDA PROGRAM CONTROL

W. P. SPAULDING

420

MISSION SUPPORT

N. A. RENZETTI, TDS MANAGER

DSN MANAGERS P. S. GOODWIN, HELIOS

R. P. LAESER, MARINER MARS 1971

K. W. LINNES, MARINER 1969

MARINER VENUS/

MERCURY

D. J. MUDGWAY, VIKING

A. J. SIEGMETH, PIONEER
A typical example of the functional interfaces between the DSN and the SFOF aft

the separation of responsibility is shown in Figure 9-8.

The Viking Mission Control Center (VMCC), which included the SFOF central compu

ing system, the mission support areas, and the Viking mission simulation system, was th

joint responsibility of the OCIS and the Viking Mission Operations System. The DSN w

responsible for the deep space stations, which included the 64-m and 26-m subnets, an

transport of data to and from the VMCC via the high-speed and wide-band data lines 

the GCF. Control and monitoring of Network performance and validation of the da

streams flowing between the VMCC and the deep space stations was to be accomplishe

by a separate data-processing capability that would be independent of the mission-relate

computers in the SFOF. These functions would be accommodated in a new Netwo

Operations Control Center (NOCC), which was being designed at the time (1972). 

600

Uplink-Downlink: A History of the Deep Space Networ

Figure 9-8. Functional interfaces between the DSN and the SFOF for Viking, 1972.

DSIF GCF

MISSION

CONTROL

(LOCAL AND

REMOTE)

NETWORK

CONTROL

JPL

CENTRAL

COMPUTERS

TRACKING AND TELEMETRY DATA

COMMAND AND MISSION

SIMULATION DATA

DSN MONITOR AND

CONTROL DATA

MISSION

INFORMATION

FOR

OPERATIONS

CONTROL

DSN STATUS

DATA EXTRACTS

FROM GCF LOG

NON-OPERATIONDRIVEN DATA

PROCESSING

DSN VIKING

FLIGHT

PROJECT
As the SFOF came into use for multi-mission support in the early 1970s, common te

minology was changed to better reflect the way in which the facility was actually bein

used. The building, JPL Building 230, and its support facilities retained the title SFO

The SFOF was eventually designated as a Historical Landmark by the U.S. Departme

of the Interior in 1986. The SFOF housed two facilities that were controlled by th

DSN, namely, the GCF (in the basement) and the NOCC (on the first floor). Th

remainder of the building accommodated the flight controllers and spacecraft analys

for the various flight projects and the data-processing equipment required to suppo

their missions. That ensemble of accommodations and equipment was called the Missio

Control and Computing Center (MCCC). It was occupied in turn by one or mo

Flight Projects for the duration of each mission, after which it was vacated and recon

figured for the next flight project. In some cases, non-JPL flight projects elected 

conduct flight operations from Mission Control Centers at their own institutions rath

than from the SFOF at JPL.

The first flight project to use the MCCC in this way was Pioneer, managed by th

Ames Research Center (ARC) in Moffett Field. Similar arrangements for remote Missio

Control Centers came into greater use in later years, as the DSN began supportin

greater numbers of non-NASA spacecraft.

The Bayley/Lyman Years

The Tracking and Data Acquisition Office at JPL (Office 400 in the JPL hierarchy) w

renamed Telecommunications and Data Acquisition Office and reached maturity und

the direction of Bill Bayley over the span of his tenure as ALD between 1967–80. Fro

a relatively small organization of fourteen in 1972 (Figure 9-7), the TDA Office ha

grown to an organization of seventy-four people, as shown in Figure 9-9, by 1978. Tw

offices—one for technology development, the other for long-range planning—had bee

added. Because of the tremendous growth in DSN flight operations and the expansio

of the Network needed to meet the increasing number of flight missions, it was nece

sary to split the former Engineering and Operations Section into separate offices. On

of these new offices (430) was managed by Renzetti and focused on developing the eng

neering systems of the DSN. Interfacing with the flight projects and scheduling antenn

time, configuration control, and all other aspects of flight mission support except th

actual hands-on operations and maintenance became the responsibility of the DSN Missio

Support Office (440), under Spaulding.

In 1980, W. H. Bayley retired and the extant JPL director, Bruce C. Murray, selecte

Peter T. Lyman to replace Bayley as ALD/TDA. Lyman retained that position un

60

The Deep Space Network as an Organization in Change
1987. Bruce Murray was succeeded as JPL Director by Lew Allen (1982), and the TD

Office continued to expand to meet the demands placed upon it by an ever-increasin

number of NASA and non-NASA deep space and Earth-orbiter missions, as well 

numerous nonflight, scientific programs. 

In Figure 9-10, a snapshot of the TDA organization, near the end of the Lyman yea

in 1986, reveals the extent of the remarkable growth of the organization in that perio

Most noticeable in this organization was the addition of the TDA Science Office (450

created by Lyman in 1983 for the reasons described in the previous chapter. Renzet

managed that new office, which included a Geodynamics program, the SETI program

the Goldstone Solar System Radar program, and several other special research project

Paul T. Westmoreland was appointed manager of the TDA Engineering Office (430

which was by then responsible for interagency arraying, compatibility and contingen

planning, and implementation of new engineering capability into the Network and GC

in addition to its ongoing task of DSN System Engineering. The TDA Planning an

Technology Development offices appeared under different managers, and they, too, ha

602

Uplink-Downlink: A History of the Deep Space Networ

Figure 9-9. TDA Office 400 organization at JPL, 1978.

400 TELECOMMUNICATIONS AND DATA ACQUISITION W. H. BAYLEY

Asst. Lab. Dir.

DSN RESIDENTS

Spain, Australia

SPECIAL PROJECTS M. Easterling

TDA PROGRAM

C. Johnson

440

TDA MISSION SUPPORT

W. Spaulding

420

TDA TECHNOLOGY

T. Thornton

430

TDA ENGINEERING

N. Renzetti

410

TDA PLANNING

E. Posner
expanded in scope. Under the management of Raymond J. Amorose, Office 440 inclu

ed management responsibility for the large Maintenance and Operations (M&O) Contrac

by which an industrial aerospace contractor provided engineering and operations ser

ices to the DSN for the Goldstone Complex, the NOCC, and related activities in th

Pasadena area. Three DSN engineers managed the M&O contract, the Network Contr

Center at JPL, and the Complex Control Center at Goldstone. Eight DSN manage

attended to the interests of over twenty flight projects that were active in the DSN 

that time. Finally, a program manager, chief engineer, and chief technologist provide

direct support for the ALD/TDA in establishing budgetary, policy, and long-term deve

opment goals.

60

The Deep Space Network as an Organization in Change

Figure 9-10. TDA Office 400 organization at JPL, 1980–87. 

JET PROPULSION LABORATORY

L. ALLEN, DIRECTOR

R. J. PARKS, DEPUTY

400

TELECOMMUNICATIONS AND DATA ACQUISITION

P. T. LYMAN

Asst. Lab. Dir.

CHIEF ENGINEER

R. Stevens TDA PROGRAM

C. W. Johnson

430

TDA ENGINEERING

P. T. Westmoreland

410

TDA PLANNING

J. W. Layland

420

TDA TECHNOLOGY

J. G. Smith

440

TDA MISSION SUPORT AND

DSN OPERATIONS

R. J. Amorose

TECHNICAL STAFF

System Engineering, Burt

GCF Engineering, Evans

Implementation, Wallace

Compatibility, Bryan

Agency Arraying, Brown

Methodology Eng., Garcia

450

TDA SCIENCE OFFICE

N. A. Renzetti

Geodynamics, Renzetti

GPS Systems, Melbourne

TDA Observatory, Levy

SETI, Klein

GSSR, Renzetti

TECHNICAL STAFF

Control Center Opns., Wyatt

Opns. and Eng. Support, Winn

DSN MANAGERS

Galileo, Mudgway

Mars Observer, Traxler

Magellan, Berman

Ulysses, Enari

ICE, Fanelli

Voyager, Cox

Radio Astronomy, Fahenstock

GSSR, SETI, Berman

GOES, Johnson

Special Projects, Goodwin
At this point, a brief digression is in order to explain the organizations by which th

three Deep Space Communications Complexes (DSCCs) that composed the DSN we

related to the TDA Office. 

From the outset, it was never intended that the various stations in the Network wou

be operated by JPL personnel. In fact, the international agreements that permitted NAS

to establish tracking stations on foreign soil stipulated that the facilities would be ope

ated by foreign nationals of the host countries. To this end, comprehensive facilities f

technical training in DSN-related technologies were set up at JPL and at Goldstone. A

these facilities, visiting foreign national engineers and U.S. national engineers receive

theoretical and hands-on instruction and training in the hardware and software whic

they would subsequently be required to operate and maintain at their home sites. In th

early life of the DSN (DSIF), when new stations were completed, a few JPL technic

personnel remained at the site until the site could sustain continued operations with i

own personnel. Later, the sites sent key personnel to the U.S. for training so that upo

their return to their home bases, they could implement the new antennas or new cap

bilities themselves. There was a constant flow of technical personnel between the sit

and Goldstone or JPL for this kind of information exchange and dissemination.

In the United States, the staff to operate the tracking stations and DSN-related servic

at Goldstone and the Network Control Center and Ground Communications Facility 

JPL were provided by a technical services contract to NASA/JPL. The Maintenance an

Operations (M&O) Contract was managed by Office 440, as discussed above, and throug

the years passed through the hands of various major U.S. aerospace companies—Bend

Field Engineering Corporation in 1960, Philco-Ford in 1970, and Bendix Field Engineerin

Corporation in 1978 and 1988. Bendix Field Engineering Corporation became Allie

Signal Aerospace in 1992 without interruption to the contract.

Under the direction of JPL personnel, the M&O contractor was responsible to the DS

for the supporting services listed below (in greatly abbreviated form):

1. At JPL:

a. Operate and maintain the Network Operations Control Center (NOCC), th

Ground Communications Facility (GCF), the Compatibility Test Facility (CT

21), and (occasionally) the DSN Launch Support Test Facility (MIL 71) 

Cape Kennedy.

b. Manage operations support programs such as antenna scheduling, discrepan

reporting, data control, radio frequency interference management, and Netwo

performance evaluation.

604

Uplink-Downlink: A History of the Deep Space Networ
c. Provide general support to all Network facilities in the areas of logistics, tech

nical training, documentation, engineering change and configuration contro

Network-level maintenance, and sustaining engineering. 

d. Provide high-level technical and administrative support for specific tasks in th

TDA Office and Telecommunications Division.

2. At the Goldstone Deep Space Communications Complex (GDSCC):

a. Operate and maintain all of the tracking stations, their intrasite communic

tions, and the research and development facility at the DSS 13 Venus site. 

b. Maintain the established Complex Maintenance Facility, Network Standar

Laboratory, and other services. 

c. Maintain all of the buildings, plant equipment, roads, lighting, power, and ai

conditioning, as well as fire, food, and security services.

The M&O Contract for Goldstone assigned complete responsibility for running the com

plex to the contractor, and over the many years of its operation, the GDSCC technic

staff were always ready to respond to a call for extra effort, whether it was for an inflig

mission, an engineering research and development task, or a DSN science program.

The staff and infrastructure needed to provide engineering and operations support f

the Canberra Deep Space Communications Complex (CDSCC) were provided b

Australian industry under a contract with the Australian government. However, all cos

associated with operation of the CDSCC were borne by NASA under the terms of th

intergovernmental agreement. The Complex Director remained an employee of the go

ernmental department (agency) charged with administering the contract on behalf 

the Australian government and was responsible to that department head for routine man

agement of the Complex, its staff, and its facilities. On behalf of NASA, the ALD/TD

at JPL was responsible only for providing the operational facilities and directing the

use in support of the NASA programs. The ALD/TDA retained a representative res

dent in Canberra to facilitate the interchange of technical and administrative informatio

between the CDSCC and JPL. He played no part, however, in the direction or oper

tion of the Complex, and the position was abolished in 1985.

International agreements between NASA and the Spanish government for the manag

ment, engineering, and operations support for the Madrid Deep Space Communicatio

Complex (MDSCC) were essentially similar to those between NASA and the Australia

government for management and operation of CDSCC. There, however, both the dire

tor and his staff were employees of a government agency, Instituto Nacional Tecnica Aerospaci

60

The Deep Space Network as an Organization in Change
(INTA), until 1992, when INTA, retaining the NASA contract, delegated the maintenan

and operation to its wholly owned company, Ingenieria y Servicios Aeroespaciales) (INSA

In both situations, this seemingly awkward organizational arrangement worked well, 

general terms. Some initial administrative difficulties were cleared up as time went on, b

the technical staffs at both complexes were always prepared (and on many occasions we

called upon) to respond unreservedly to the exigencies of deep space mission operation

The Dumas/Haynes Years

When the position of Deputy to the Director of JPL became vacant at the retireme

of Robert Parks in 1987, Lyman was appointed to fill the position, and Larry N. Dum

became ALD/TDA. Apart from the inevitable personnel changes and some structur

changes within the five internal offices of the TDA (400) organization, little change

in an organizational sense in the DSN during the Dumas years, 1987 to 1992. Mo

changes in upper management, however, were on the way.

In 1990, Edward C. Stone replaced Allen as director of JPL, and he was joined in 199

by Dumas as deputy. The then vacant position of ALD/TDA was filled by Norman R

Haynes, who brought Westmoreland from the TDA Engineering Office to become h

deputy. The TDA organization had remained essentially unchanged since 1986, an

except for changes in personnel, is well represented by Figure 9-11. This was the fin

form of the TDA Office. There was no hint of the very dramatic changes that wou

overtake the entire TDA (400) organization in the next several years.

When Haynes took over the TDA organization in 1992, it was one of several offic

headed by an Assistant Laboratory Director (ALD). These offices, under the JPL dire

tor, composed the basic structure of the entire JPL organization. When he left in 199

the JPL structure had been changed to one based upon an ensemble of directorate

each headed by its own director. The directorates were not simply renamed offices, b

were restructured to reflect the “policy for change” brought to JPL by the new directo

E. C. Stone.

To fully appreciate the latest changes in the TDA organization, it is necessary to unde

stand the organizations at NASA Headquarters and in the MCCC at JPL at that tim

Both influenced the shape of the future TDA organization.

606

Uplink-Downlink: A History of the Deep Space Networ
60

The Deep Space Network as an Organization in Change

Fi

9

11

N

ti

l A

ti

d S

Ad

i

i

t

ti

1991

E

ADMINISTRATOR

RICHARD H. TRULY

DEPUTY ADMINISTRATOR

JAMES R. THOMPSON, JR.

ASSOCIATE DEPUTY ADMINISTRATOR

SAMUEL W. KELLER

ASSISTANT DEPUTY ADMINISTRATOR

JOHN E. O’BRIEN

EXECUTIVE OFFICER

JESSIE J. HARRIS

AEROSPACE SAFETY

ADVISORY PANEL

NASA ADVISORY

COUNCIL

INSPECTOR

GENERAL

DIRECTOR, SMALL &

DISADVANTAGED

BUSINESS UTILIZATION

EUGENE D. ROSEN

BILL D. COLVIN

W

K

COMPTROLLER

B

GENERAL

COUNSEL

G ASSISTANT

ADMINISTRATOR

FOR EQUAL

OPPORTUNITY

PROGRAMS

X ASSOCIATE

ADMINISTRATOR

FOR

EXTERNAL

RELATIONS

L ASSISTANT

ADMINISTRATOR

FOR

LEGISLATIVE

AFFAIRS

MARTIN P. KRESS MARGARET G. FINARELLI DR. HARRIETT G. JENKINS EDWARD A. FRANKLE THOMAS CAMPBELL

COMPTROLLER

B

H

COMPTROLLER

B ASSISTANT

ADMINISTRATOR

FOR

HEADQUARTERS

OPERATIONS

D ASSISTANT

ADMINISTRATOR

FOR

PROCUREMENT

P ASSOCIATE

ADMINISTRATOR

FOR

PUBLIC AFFAIRS

N ASSOCIATE

ADMINISTRATOR

FOR

MANAGEMENT

DR. C. HOWARD ROBINS, JR. WILLIAM SHEEHAN DON G. BUSH (ACT) BENITA A. COOPER JAMES T. ROSE

ASSISTANT

ADMINISTRATOR

FOR

COMMERCIAL

PROGRAMS

C Q ASSISTANT

ADMINISTRATOR

FOR SAFETY &

MISSION QUALITY

GEORGE A. RODNEY

O ASSOCIATE

ADMINISTRATOR

FOR SPACE

OPERATIONS

CHARLES T. FORCE

R ASSOCIATE

ADMINISTRATOR

FOR AERONAUTICS

EXPLORATION &

TECHNOLOGY

ARNOLD D. ALDRICH

M ASSOCIATE

ADMINISTRATOR

FOR

SPACE FLIGHT

DR. WILLIAM B. LENOIR

S ASSOCIATE

ADMINISTRATOR

FOR SPACE

SCIENCE &

APPLICATIONS

DR. LENNARD A. FISK

LYNDON B. JOHNSON

SPACE CENTER

AARON COHEN

JOHN F. KENNEDY

SPACE CENTER

LT. GEN. FORREST McCARTNEY

GEORGE C. MARSHALL

SPACE FLIGHT CENTER

THOMAS J. LEE

JOHN C. STENNIS

 SPACE CENTER

ROY S. ESTESS

AMES

RESEARCH CENTER

DR. DALE L. COMPTON

LANGLEY

RESEARCH CENTER

RICHARD H. PETERSEN

LEWIS

RESEARCH CENTER

LAWRENCE J. ROSS

GODDARD SPACE

FLIGHT CENTER

DR. JOHN M. KLINEBERG

JET PROPULSION

LABORATORY

DR. EDWARD STONE

A
By 1991, the organization at NASA Headquarters under Administrator Richard H. Tru

included an Office of Space Science and Applications (OSSA, Code S) and an Offi

of Space Operations (OSO, Code O) as shown in Figure 9-11.

In the context of program direction for users and suppliers of deep space tracking an

data-acquisition services, OSSA directed the flight projects (users) and associated groun

data-processing facilities (MCCC) while OSO directed the TDA Office and its assoc

ated tracking and data-acquisition facilities (DSN).

For clarification, during the period of DSN history reviewed in this book, the NAS

office that began as the Office of Tracking and Data Acquisition (OTDA) in 196

became the Office of Space Tracking and Data Systems (OSTDS) in 1983, the Offi

of Space Operations (OSO) in 1988, and the Office of Space Communications (OSC

in 1992. During almost that entire period, it was identified as “Code O” and was respon

sible for programmatic direction of the DSN through the TDA Office at JPL.

The selection in July 1989 of Charles T. Force as Associate Administrator of the Offi

of Space Operations (OSO) brought immediate changes to the DSN relationship wi

NASA Headquarters. His highly relevant technical background, considerable experien

in tracking-network operations, and strong motivation effectively streamlined th

unwieldy, outmoded, and by that time largely irrelevant system of documentation th

controlled agreements for providing and expending NASA resources on the DSN anten

nas. The time span of his position in that office, 1989–96, placed him squarely in th

Galileo Era, where he was most effective, at the Headquarters level, during the cris

that arose in that period of DSN history.

The funding approved during Force’s tenure enabled the DSN to upgrade the 64-

antennas to 70-m, add more 34-m antennas to the Network, support recovery of th

Galileo mission from almost certain failure, introduce multiple antenna arraying on 

routine operational basis, move toward K-band operations, and consolidate and upgrad

the Signal Processing Centers. Together with the improvements in formal Headquarte

documentation, these made an impressive record of achievement that set the stage f

the major reorganization that swept through all the NASA Networks in the late 1990

Forceful in attitude and spare with words, “Charlie” Force came straight to the poi

in a discussion, an aspect of his managerial style that appealed to the JPL managers wi

whom he interacted on DSN-related matters. His full responsibilities included sever

other NASA Networks in addition to the DSN, and he was seen as fair and imparti

608

Uplink-Downlink: A History of the Deep Space Networ
when at times his decisions regarding the allocation of limited resources were at od

with prevailing opinions at JPL.

Force joined NASA in 1965 as Director of the Guam Tracking Station and, except f

returning to industry for a couple of years in the early 1980s, held increasingly respon

sible positions throughout his career at NASA. A native of Shoals, Indiana, and reside

of the state of Maryland, he held a B.S. degree in aeronautical engineering from Purdu

University. Force left NASA in 1996 to pursue commercial business interests.

By 1993, the organization at JPL formerly referred to as the MCCC had embraced th

concept of multi-mission operations and had evolved into the Multimission Operation

Systems Office (440) with the structure shown in Figure 9-12.

Because of its close association with the evolution of the DSN, the path by which th

MCCC evolved is of historical interest and is neatly described by Alazard9 as follows

From the mid-1960s through 1970, the ground data system was comprised of

three IBM 7094 computers to support each of the then current (flight) projects. Between 1970 and 1977, the architecture and organization of computing

changed and moved toward a multimission orientation. The Mission Control

60

The Deep Space Network as an Organization in Change

Figure 9-12. Multimission Operations Systems Office (440), 1993.

MULTIMISSION OPERATIONS

SYSTEMS OFFICE (220)

Mgr.

Dep. Mgr.

Asst. Mgr. - Operations

Asst. Mgr. - Development

Chief Engineer

PROGRAM

CONTROL &

ADMINISTRATION

SYSTEM

ENGINEERING

ADVANCED

SYSTEMS

FLIGHT

PROJECTS

INTERFACE

SYSTEM

INTEGRATION

AND

VERIFICATION

FACILITIES

SCIENCE

INFORMATION

ARCHIVE

(SISO)

SPACECRAFT

ANALYSIS

NAVIGATION PLANNING

AND

SEQUENCING

OPERATIONAL

SCIENCE

ANALYSIS

TELEMETRY MISSION

CONTROL AND

DATA

MANAGEMENT

COMPUTER

AND

COMMUNICATION

MOSO MANAGERS

FUNCTIONAL AREA MANAGERS
and Computing Center (MCCC) was created and data processing was done

on IBM 360-75’s. The flight projects shared this single system in a multiprocessing mode. Between 1973 and 1981, minicomputers were phased into the

MCCC for realtime processing. Mainframe computers were used for processing (flight) project applications programs and data records[,] i.e.[,] non-realtime

processing. These computing capabilities were provided to the flight projects

by the Fight Projects Support Office (FPSO). The realtime processors were usually dedicated to a given project while the non-realtime processors were shared.

In an effort to reduce the cost of data processing for flight operations in the

mid-1980s, FPSO initiated development of an entirely new facility, called the

Space Flight Operations Center (SFOC). The SFOC performed the functions

of the MCCC with the newer technology of distributed processing using microcomputers and local area networks in a workstation environment. When it was

completed in the early 1990s, existing flight project support was gradually converted from the MCCC to the new system, and new flight projects were adapted

to the multimission capabilities and services. In due course the MCCC was

phased out and the SFOC became the core of an even more advanced data processing system called the Advanced Multi-Mission Operations System (AMMOS).

The name FPSO was changed to Multimission Operations Systems Office (MOSO) 

1992 to better reflect the multi-mission nature of the organization. MOSO became th

overall organization responsible for development, operations, and maintenance of th

flight project support capabilities. AMMOS provided the direct operations support fun

tions using the hardware and software of the Multimission Ground Data System (MGDS

It was the task of MOSO to establish the set of multi-mission data processing capab

ities and operational services that supported the flight projects in accomplishing the

mission objectives. The AMMOS was the set of hardware and software tools by whic

this task was accomplished. Defined in this way, the MOSO task closely paralleled th

DSN Operations and Mission Support Office (440) task when tracking and data-acqu

sition services were substituted for data-processing services and the DSN was substitute

for AMMOS. The MGDS was the counterpart of the DSN.

The JPL Strategic Plan: 1994

Shortly after the Clinton Administration took office in January 1993, all federal age

cies, including NASA, began to feel the effect of a groundswell of change toward a smalle

more efficient, and less costly bureaucracy. A new NASA Administrator, Daniel S. Goldi

610

Uplink-Downlink: A History of the Deep Space Networ
had been appointed early in 1992, and he was quick to respond to the presidential in

tiative for cost reduction in government agencies. In the course of the changes that followe

the Headquarters organization was significantly reduced in size; many functions we

deleted or combined; and a new, streamlined NASA organization emerged. In an env

ronment of economic constraints and redefined national goals, the NASA budget decline

in Fiscal Year 1995 for the first time since the end of the Apollo program in the la

1960s. New approaches and revised priorities for the U.S. space program were develope

to ensure that space science and technology would continue to advance for the bene

of the nation. All of these factors required NASA and, consequently, JPL to rethink the

ways of doing business, adopt new strategies, and create a shared understanding of ho

to meet customer needs in the new environment.

This state of affairs formed the driver for a Strategic Plan developed for JPL in 199

by its new director, Edward C. Stone.10 It defined the set of NASA programs in whic

61

The Deep Space Network as an Organization in Change

Figure 9-13. NASA Space Communications and Operations Program.

NASA SPACE COMMUNICATIONS AND OPERATIONS PROGRAM

• Provide affordable, world-class support to large, complex missions: Ulysses, Galileo,

Cassini, and EOS.

• Advance the state of the art in low-cost support of small and moderate missions. 

• Develop the capability to provide Ka-band services for future low-cost missions. 

• Upgrade mission operations concepts and support systems to enable simultaneous

operation of many missions at significantly reduced unit cost. 

• Develop concepts for promising new services such as optical communications and

non-DSN tracking terminals. 

• Revolutionize ground system designs to reduce complexity and operating costs while

emphasizing new technology opportunities and controlled risk. 

• Support many more missions in the next five years while reducing DSN tracking operations costs by 50 percent. 

• Advance the state of the art in deep space and near-Earth navigation and communications to meet expected future mission requirements.

• Seek new concepts for low-cost support of small and moderate missions. 

• Increase the use and scientific impact of the DSN in radio science, astronomy, and

planetary radar studies.

• Lead in developing international science agreements and cross-support systems for

an affordable global space exploration program.
JPL would engage to support “NASA’s strategic enterprises and other national needs

One of these programs was NASA Space Communications and Operations, and becau

of its importance to the future long-term development of the DSN, it is reproduced 

Figure 9-13.

One of the overarching concepts embodied in the newly defined program was the com

bining of space communications with space operations to create a single entity of reduce

complexity with lower operating costs. This was to be achieved without sacrificing pe

formance and was concomitant with a stimulating call to further advance the state 

the art in associated technologies.

Birth of the TMOD

The Telecommunications and Mission Operations Directorate (TMOD) was created 

1994 to support the NASA Space Communications and Operations program define

in the Strategic Plan described above. As such, it represented one element of the Laboratory

overall response to the NASA Strategic Plan. 

The transition from the TDA organization to the TMOD organization took place du

ing the latter half of the Haynes years (1994); although there was a considerable disruptio

of ongoing activities initially, by 1996, when Paul T. Westmoreland assumed the pos

tion of Director, the new arrangement had settled down and assumed the form show

in Figure 9-14.

The rearrangement and consolidation of former TDA functions, which is apparent 

Figure 9-14, reflected a new and cost- effective approach to complex business manag

ment systems made popular at that time (1992–93) by Dr. Michael Hammer, co-auth

of the book Reengineering the Corporation.

11 With institutional encouragement, JPL man

agement personnel at all levels attended Hammer’s courses and returned to JPL to app

the new methodology to the workplace. Early in 1994, the TDA senior staff spent tw

months developing a process map for the TDA organization. Two of these process

were selected for actual reengineering, and process owners were named. The selecte

processes and owners were Services Fulfillment (Raymond J. Amorose) and Asset Creatio

(Edward L. McKinley). Leslie J. Deutsch was assigned to lead the Reengineering Tea

(RET) for Services Fulfillment—the process deemed most suitable for the first eng

neering effort. Although the RET was formed initially to reengineer only the TD

organization, the scope of its work was expanded to include the data capture and na

igation functions of MOSO when the two organizations were merged to form TMOD

612

Uplink-Downlink: A History of the Deep Space Networ
The RET issued an interim report in September 1994 containing some key items f

the future structure of TMOD. Among these were the three Services Fulfillment Process

recommended for reengineering—namely, Data Capture, Activity Planning, and Resourc

Scheduling, all defined later in this chapter. There was also a proposal that the DSN b

changed from an engineering-driven organization, as it had stood in the past, to an ope

ations-driven organization for the future.

The arrangement shown in Figure 9-14 was the first step in the overall reengineerin

process. Essentially, the former TDA organization was condensed into two offices: on

for planning, committing, and allocating DSN resources; the other for DSN oper

tions and system engineering. DSN science and technology were incorporated in th

former, DSN development in the latter. In addition to these two offices, the Multimissio

Ground Systems Office, the project offices of the four inflight missions (Galileo, Spa

VLBI, Ulysses, and Voyager) and a new business office were added to create TMOD

There could be little doubt that the TMOD was now operations-driven rather tha

engineering-driven.

61

The Deep Space Network as an Organization in Change

Figure 9-14. Telecommunications and Mission Operations Directorate, 1996.

TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE

P. T. Westmoreland, Director

R. C. Coffin, Program Manager

900

L. J. Deutsch, Chief Systems Architect

R. P. Mathison, Chief Engineer

R. G. Polansky, Assistant Chief Engineer

G. F. Squibb, Chief Mission Operations Architect

R. J. Wallace, NASA Liaison

900

GALILEO PROJECT

W. J. O’Neil, Mgr.

950

U.S. SVLBI PROJECT

J. G. Smith, Mgr.

960

ULYSSES PROJECT

E. B. Massey, Mgr.

980

VOYAGER PROJECT

G. P. Textor, Mgr.

990

MULTIMISSION GROUND SYSTEMS OFFICE

T. D. Linick, Mgr. S. M. Huffman, Deputy Mgr.

970

DSN DATA SERVICES OFFICE

E. L. McKinley, Mgr.

M. E. Wyatt, Deputy Mgr.

J. A. Wackley, Deputy Mgr.

940

TMO PLANS AND COMMITMENTS OFFICE

R. B. Miller, Mgr. D. G. Griffith, Deputy Mgr.

920

• TMO LEVEL 0 SYSTEM

ENGINEERING

• STRATEGY DEVEL.

• DSN TECHNOLOGY

• DSN SCIENCE

• FUTURE MISSIONS

PLANNING/COMMITMENT

• RESOURCE ALLOCATION

• DSN (LVL 1) SYSTEM ENG’G

• DSN DEVELOPMENT

• DSN OPERATIONS

• AMMOS (LVL 1) SYSTEM ENG’G

• AMMOS DEVELOPMENT

• MULTIMISSION GDS DEVEL.

• PROJECT GDS DEVEL.

• AMMOS OPERATIONS

LEGEND:

AMMOS = Advanced Multimission Operations Systems

DSN = Deep Space Network

TMO = Telecommunications and Mission Operations

(XXX) = Administrative Organization

BUSINESS OPERATIONS

OFFICE

C. T. Stevens, Manager

910
While these organizational changes brought the Deep Space Network and th

Multimission Ground Data System together under one directorate, they did not effec

alone, the substantial reduction in ground operations costs that was the real objectiv

of the reengineering initiative. DSN operations, now redefined in reengineering term

as the Data Capture Process, still involved a plethora of facilities, starting with th

DSCCs, passing through the GCF to the NOCC and to MOSO before eventual

delivering the data to the customer. Reduced cost would come from reduction in th

size, complexity, redundancy, and performance margin of the infrastructure needed 

operate these separate facilities. This, in turn, required a radical change in the way 

which future operations were performed, and in the way in which the individual el

ments of the Data Capture Process would be operated. It was the task of the RET 

show how this could be done and to provide a road map for making the transition 

the new Data Capture Process.

614

Uplink-Downlink: A History of the Deep Space Networ
REINVENTING THE FUTURE (1994 INTO THE NEW MILLENNIUM)

Reengineering TMOD

The RET completed its redesign of key TMOD subprocesses and submitted its fin

report to DSN Mission Operations Manager Ray Amorose in March 1995.12 It su

ceeded in not only meeting but exceeding its initial cost and efficiency goals of reducin

the DSN Operations budget by $9M and doubling the available tracking hours by Fisc

Year 1999. The new designs would cost about $16M to implement and were predic

ed to result in a cumulative savings to TMOD Services Fulfillment of approximate

$35M for the period FY 1996 through FY 2000, as shown in Figure 9-15.

61

The Deep Space Network as an Organization in Change

Figure 9-15. Predicted cost and savings for reengineering TMOD Services Fulfillme

Processes. The three Services Fulfillment Processes include the following:

1. Data Capture—the process that provided the services of telecommunications, target trackin

and data processing to customers. 

2. Activity Planning—the process that generated and consolidated the support data that was nee

ed by the Data Capture Process to perform its functions. 

3. Scheduling—the process that allocated the resources of the DSN and MGDS for use in the Da

Capture Process.

40.0

35.0

30.0

25.0

20.0

15.0

10.0

5.0

0.0

$M (Real Year)

FY95 FY96 FY97 FY98 FY99 FY00

Year

Cumulative Impl. Cost ($M) Cumulative Savings ($M)
Because the savings to DSN Operations were estimated to be low, the RET elected n

to reengineer the Scheduling Process at that time. It was, therefore, only the Data Captu

and Activity Planning Processes that, in reengineered form, contributed to the substan

tial projected cost savings noted above.

By basing its design on standard (rather than customized) services, the new Data Captu

Process simplified mission interfaces, increased operational efficiency, and allowed fu

use of automation to provide these services. At the same time, a “Connection Operato

was made available to provide specially tailored services essential to the customer’s need

The parts of the NOCC, GCF, and MGDS involved in real-time operations were broug

together in a single work area called Central Operations. New, more easily maintaine

equipment allowed them to be located in a considerably smaller work space with reduce

facilities costs.

On the other hand, supporting data such as radio metric predicts, antenna pointin

instructions, and schedules for Deep Space Network operations were considered an Activi

Planning function and had, in past practice, been generated at the NOCC considerab

in advance of the needed time. The inputs were, of necessity, immature, and they invar

ably led to the generation of many contingency or “just in case” versions, all of whic

created extra work. In the new, more rapid and efficient “just in time” system, predic

were generated at the site as needed and were based on the most up-to-date requir

ments and conditions. The resulting system was much more responsive to last-minu

changes, more timely, more accurate, and less costly to operate.

Data Capture Process

The new Data Capture Process described above was critically dependent for its impl

mentation on the availability of new hardware and software tools with the requisi

capabilities. To a large degree, these were to be provided out of similar studies carrie

out by the Reengineering Team for the Asset Creation Process, which ran a parall

course to that of Customer Services Fulfillment.

In this context, it was assumed that the operations load on the 26-m/9-m subnetwo

would be relieved by the introduction of a subnetwork of small unattended tracking st

tions to be known as Low-Earth Orbit (LEO) terminals. It was further assumed th

updated electronics would allow a large degree of automation for future operation 

the 26-m and 9-m antennas and would eliminate the existing need for roving operato

(rovers) to configure antenna and microwave equipment in front-end areas (FEAs). A

the DSCCs, the already-planned Advanced DSN Monitor and Control (ADMC) su

616

Uplink-Downlink: A History of the Deep Space Networ
61

The Deep Space Network as an Organization in Change

Figure 9-16. Data Capture road map.

• ADMC-2 Improved Automation• WAN• Improved FEAs• Data Management System• Network Monitoring Tools

Transition to ConnectionOps

Improved connection control & visibility;eliminate need for “rovers” and FEA operators

Multiple (>2) Connections per Operator

ConsolidateCentral Ops

DSOTAutomation

Reduce/Automate ResourceAllocation at Sites

Transition to NOD & Exception Handling

1995 1996 1997 1998 1999 2000

• ADMC-3, CMC Capabilities• Automation for Resource Alloc.

ADMC-1

• ConnOps for multiple

customers

• Automated Resource

Allocation at DSCCs

• Streamlined Central Ops• Central support for

Exception Handling

• Data Management

system in place tosupport RT & NRT opsand analysis

• Solid foundation for

future evolution
system would provide the high degree of automatic features required for the Connectio

Operations concept. A new “Reliable Data Delivery System” and improved Wide Ar

Network were already at the advanced design stage and were assumed to be available 

meet the proposed transition plan schedule. Finally, it was assumed that technolog

already developed in MOSO for data processing and management would be extende

to incorporate the Data Systems Operations Team (DSOT) as a vital element of th

new Data Capture system.

A road map for making the transition to the new Data Capture Process is shown 

Figure 9-16.

The dependency on key new implementation described above is shown in the top ha

of the figure, while the key changes in operations processes are shown in the lower ha

The plan attempted to minimize disruption to ongoing operations while it progresse

rapidly toward its final realization by 2000. Near-term savings accrued from the ear

transition to Connection Operation in 1995, collocation of TMOD operations, an

reduction in operations documentation. 

Activity Plan Process

The two principal functions performed via the Activity Plan process were as follows:

1. Identifying the services to be provided. This was called Service Plan Generation an

was based on a schedule showing the TMOD resources required and the time at whic

they were to be available, as well as a project sequence of events (PSOE) that identifie

what the customer would be doing during the time allocated in the schedule. 

2. Generating the information, internal to the Network, that was required for opera

ing the equipment to provide the needed services. This was called Predicts Generatio

and was required principally for generation of radio metric or telemetry data. It w

based on spacecraft state and ephemeris and station-dependent data such as locatio

horizon mask, and planetary ephemeris.

At the time that the new Activity Plan Process was being designed, a standard infrastru

ture for the packaging and manipulation of spacecraft navigation products called the “SPICE

system had been in use for some years at JPL. The SPICE data sets were called kerne

and contained the information necessary to assist users in planning and interpreting sc

ence observations from spacecraft instruments. For example, the “S” data set containe

spacecraft ephemeris data, and the “P” data set contained planetary ephemerides.

618

Uplink-Downlink: A History of the Deep Space Networ
In reengineering the Activity Plan Process, the RET extended this idea to create kerne

containing spacecraft and planetary ephemerides data, telemetry data, station informatio

and time and Earth polar motion information needed to compute station locations. Th

data bases of these kernels would be “shadowed” or automatically updated to the trackin

station’s data management system and would therefore be available for use in generatin

telemetry and/or metric predicts on demand. At the station, computation of predicts cou

be initiated only minutes before the actual activity was scheduled to take place.

In addition to these innovations, the reengineered Activity Plan Process improved th

way in which the customer provided the PSOE by referencing it to a standard catalo

of prenegotiated services. The Activity Plan Process would then translate these servi

requests into the operations procedures necessary to meet them, thereby creating th

actual Service Plan.

Although implementation of the new Activity Plan Process began in 1995, it depen

ed on upgraded versions of the data management capability at the stations for full operatio

Delay in providing this new capability resulted in a longer term return on the impl

mentation costs than was the case for the Data Capture Process. 

At the time of this writing, the implementation plans for the Data Capture and Activi

Plan Processes were in progress along the lines discussed above. When fully completed 

1999, the reengineered TMOD Customer Services Fulfillment Process would embody th

very best principles of cost-effective, process-based management, rather than the facility-base

management and control principles that had been in place for the previous forty years. 

Reinventing the Future 

After a very short term of one year in office, Westmoreland retired in June 1997, an

Gael F. Squibb was appointed director of the Telecommunications and Mission Operation

Directorate (TMOD). Squibb was well qualified to guide TMOD into the future. H

had served as Manager of Data Services for NASA’s Space Operations Manageme

Office since 1995 and had managed numerous scientific flight projects in thirty yea

of previous service with JPL.

When Squibb took over TMOD, the reengineering effort was well under way and th

DSN and MGDS functions in mission operations had become recognized as contiguo

elements of the Customer Services Fulfillment Process. They were, from 1994, still se

arate offices (940 and 970) of the original TMOD organization. It was time to bring th

institutional organization more into line with the concepts of process-based managemen

61

The Deep Space Network as an Organization in Change
The restructured Telecommunications and Mission Operations Directorate, under th

direction of Gael Squibb in 1997, is shown in Figure 9-17.

The former DSN Data Services and Multimission Ground Systems Offices were combine

to form the TMOD Operations Office, from which the Customer Services Fulfillme

Process, including the allocation of resources, would be managed effectively. To develo

the new system engineering functions for this process, a TMOD Engineering Office, whic

included engineering elements of both the DSN and MGDS, was also created. It wou

be here that the Asset Creation Process would reside. The enabling technology on whic

the reengineering teams based their new process-oriented designs was to be provided b

the TMOD Technology Office for both the DSN and AMMOS. It was defined as 

“Center of Excellence” for telecommunications to focus attention on the particular tec

nology in which the DSN held a unique position in the NASA sphere of influence. Th

Plans and Commitments Office and flight project offices remained essentially the same

620

Uplink-Downlink: A History of the Deep Space Networ

Figure 9-17. Telecommunications and Mission Operations Directorate, 1997.

TELECOMMUNICATIONS AND MISSION

OPERATIONS DIRECTORATE

G. F. Squibb, Director

R. C. Coffin, Program Manager

900

P. T. Westmoreland, Transition Advisor

R. P. Mathison, Chief Engineer

R. G. Polansky, Assistant Chief Engineer

M. J. Rodngues, Asst. Prog. Mgr. for SOMO/CSOC Operations

E. L. McKinley, Mgr. SOMO Data Services

900

• TMO LEVEL ENG’G

• MOS SYSTEM ENG’G

• STRATEGY DEVEL.

• DSN SCIENCE

• FUTURE MISSIONS

PLANNING

• PROJECT INTERFACE/

COMMITMENT

• DSN/AMMOS DEVEL.

• PROJ. GDS DEVEL.

• DSN/AMMOS OPERATIONS

• FLIGHT MISSION OPS

• PROJECT MOS MGMT.

• CSOC MANAGEMENT

• RESOURCE ALLOCATION

LEGEND:

DSN = Deep Space Network

TMO = Telecommunications and Mission Operations

(XXX) = Administrative/Home Organization

(CTR) = Contractor

GALILEO PROJECT

VOYAGER PROJECT

ULYSSES PROJECT

SPACE VLBI PROJECT

TMOD OPERATIONS OFFICE

T. Dl. Linick, Mgr. J. A Wackley, Dep.

TMOD TECHNOLOGY OFFICE

L. J. Deutsch, Mgr.

C. D. Edwards, Dep.

TMOD ENGINEERING OFFICE

J. I. Statman, Mgr.

J. C. Klose, Dep.

TMOD PLANS AND

COMMITMENTS OFFICE

R. B. Miller, Mgr.

D. G. Griffith, Dep.

• FLT/GRND TECHNOLOGY

DEVEL.

• DSN & AMMOS TECHNOLOGY

DEVEL.

• TELECOM. CENTER OF

EXCELLENCE

BUSINESS OPERATIONS

OFFICE

C. T. Stevens, Manager

910
There was another feature of the TMOD organization that, although not apparent o

the organization chart, affected the interaction between TMOD and its customers in 

significant way—the change in the role of the DSN manager. As mentioned earlier, 

was customary for the TDA Office to appoint a representative to work with each flig

project in negotiating and using the tracking and data acquisition services that we

required for its mission. The title of this position was “Tracking and Data System (TD

Manager for (Name of Customer).” 

Customers included those that used the DSN as a scientific instrument as well as tho

that used it as a tracking and data acquisition service. The TDS manager helped h

designated customers to understand relevant technical and operational aspects of th

DSN and acted as an authoritative single point of contact for the customers, dealin

with all aspects of the service being provided. But the service rendered extended on

to the interface between the DSN and the MGDS. It did not include the processin

and management of the data beyond that point, which was, in reengineering term

“facility-oriented.” When TMOD was reengineered into a “process-oriented” organiz

tion, the former TDS manager positions, which were properly resident in the Plans an

Commitments Office, were expanded in concept and scope to include the entire Custom

Fulfillment Services Process. They became the TMOD version of the “empowered cu

tomer service representatives” advocated by Hammer and Champy and were calle

Telecommunications and Mission Services (TMS) Managers. 

The extent to which a single person would be able to discharge this task in a mean

ingful way at all levels throughout the now extremely complex Services Fulfillment proce

remained to be seen. Hammer and Champy recognized this problem and observed, “T

perform this role–that is, to be able to answer the customer’s questions and solve th

customer’s problems–the case manager needs access to all the information systems th

the people actually performing the process use and the ability to contact those peop

with questions and requests for further assistance when necessary.” The TMS manage

of the future would need full access to tools and resources such as these to proper

carry out their important functions in the new process-oriented TMOD.

“Bridging the Space Frontier”

A few months after taking office, the new director of TMOD issued a statement th

presented his goals and vision for the TMOD of the future. It included a plan for the

realization and was called “Bridging the Space Frontier.”13 The plan traced the origin 

the powerful forces throughout NASA that had influenced the organizational structu

of TMOD and would determine its course for the future. The environment in whic

62

The Deep Space Network as an Organization in Change
TMOD must plan for the future, said Squibb, “is characterized by three fundament

trends: increasing demand for telecommunication and mission services and technolog

advancements, highly constrained resources, and organizational change.” 

Squibb based his plan on NASA’s response to the National Space Policy, issued fro

the White House in 1996.14 The National Space Policy of 1996 directed NASA to foc

its research and development efforts in the four principal areas of Space Science, Ear

Observation, Human Space Flight, and Space Technologies and Applications. Furthermor

it instructed NASA to “seek to privatize or commercialize its space communication

operations no later than 2005” and to “examine with DoD, NOAA[,] and other appr

priate federal agencies, the feasibility of consolidating ground facilities and da

communications systems that cannot otherwise be provided by the private sector.”

NASA began to address this latter policy by consolidating the management of all i

space operations under a new Space Operations Management Office (SOMO), locate

at the Johnson Space Center in Houston. As the service provider, SOMO was give

responsibility for implementing NASA’s space operations and managing the associate

space operations work process. The NASA Centers, in support of their respective impl

mentation plans for space operations, were responsible for the execution of the spa

operations work process.15

In his plan, Squibb discussed TMOD’s relationship to SOMO. “Through this coope

ative arrangement with SOMO, TMOD (would) oversee operation of the Advance

Multimission Operations System (AMMOS) and the Deep Space Network (DSN). Und

SOMO’s leadership, efforts were underway to consolidate and streamline major suppo

contract services.” Transition to a Consolidated Space Operations Contract (CSOC) wi

a single, ten-year, cost-plus-award-fee contract was expected to begin in Fiscal Year 199

In the meantime, TMOD worked to understand its future, dramatically different ro

as a partner with a CSOC contractor, and possibly with other United States or foreig

agencies; it also tried to identify any functional activities that would be suitable for com

mercialization in the immediate future.

JPL’s management responsibilities for the DSN and AMMOS were finally combine

under Squibb’s direction in 1996, and TMOD began to operate as a single proces

oriented service to its customers. Joe Statman, manager of the TMOD Engineerin

Office, saw the new way of operating as a challenge to “create one culture—no mo

separate DSN/AMMOS cultures.” One step remained, however, in the completion 

the DSN/AMMOS unification, and that had to do with the still separate sources 

programmatic direction at NASA Headquarters.

622

Uplink-Downlink: A History of the Deep Space Networ
The directives of the 1996 National Space Policy, and its focus on NASA research an

development efforts, were eventually manifested in the NASA Strategic Plan.16 This calle

62

The Deep Space Network as an Organization in Change

Figure 9-18. Organization of the National Aeronautics and Space Administration, 1996. In t

new organization, the responsibilities of Code O (the former Office of Space Communications) we

distributed among the Centers, the Office of Space Flight, and the Space Operations Manageme

Office (SOMO). It was SOMO that provided programmatic direction for the DSN-related elemen

of TMOD. Code S, the home of the Space Science Enterprise, continued to provide the source 

funding for the MGDS-related elements of TMOD. 

GODDARD

SPACE FLIGHT

CENTER

NASA

ADMINISTRATOR

Daniel S. Goldin

Codes H, P, Z Codes B, G, E Codes I, L, F Codes J, G, C

Codes K, X, U

Code O

SPACE

COMMUNICATIONS

MARSHALL

SPACE FLIGHT

CENTER

STENNIS

SPACE CENTER

KENNEDY

SPACE CENTER

JOHNSON

SPACE CENTER

LEWIS

RESEARCH

CENTER

STENNIS

SPACE CENTER

KENNEDY

SPACE CENTER

AMES

RESEARCH

CENTER

LANGLEY

RESEARCH

CENTER

DRYDEN FLIGHT

RESEARCH

CENTER

JET

PROPULSION

LABORATORY*

Code Y

ENTERPRISE

MISSION TO

PLANET EARTH

Code M

ENTERPRISE

SPACE FLIGHT

Code R

ENTERPRISE

AERONAUTICS

Code S

ENTERPRISE

SPACE SCIENCE

* JPL is a contractor-operated

facility.
for a restructuring of the NASA organization based on four grand “Strategic Enterprises

The organizational structure took the form shown in Figure 9-18. 

Plans held that by Fiscal Year FY 1999, when the Consolidated Space Operations Contra

(CSOC) would be in effect, CSOC would have responsibility for both the DSN an

AMMOS elements of TMOD. With that final step, the DSN/AMMOS unificatio

would be complete.

NOTE: Each of the four Strategic Enterprises was affiliated with one or more of the NAS

Field Centers as shown in the chart. The Space Science Enterprise was affiliated with JP

However, it was from endeavors in support of the Space Science, Mission to Planet Eart

and Space Flight Enterprises that requirements for the data and mission services that we

the prerogative of TMOD would be derived. Two of the four Enterprises were subsequent

renamed as their missions were revised. In 1997, the four Enterprises were named Spa

Science, Mission to Planet Earth, Human Exploration and Development of Space, an

Aeronautics and Space Transportation Technology.

TMOD Primary Challenge: 1997

In the 1998 Strategic Plan, NASA established the following near-term, mid-term, an

long-term goals for the four Enterprises: 

• 1991–2002: Establish a virtual presence throughout the solar system

• 2003–09: Expand the horizons

• 2010–23: Develop the frontiers

Commensurate with these goals, SOMO estimated that the Space Science Enterpri

would require data and mission services support for 86 missions through 2004; Missio

to Planet Earth would require support for 34 missions; and Human Exploration an

Development of Space would require support for 18 missions. A significant number 

these missions would involve TMOD and, with more complex investigations and instr

ments characterizing these missions, would lead to a dramatic increase in the deman

for data and mission services over the next several years. This, said Squibb, would tak

place against an environment of highly constrained, albeit level, budget resources. Th

situation and the scope of the challenge it presented to TMOD were well illustrated 

the graphic shown in the 1997 Space Communications Budget Review and reproduce

in Figure 9-19.

624

Uplink-Downlink: A History of the Deep Space Networ
As 1997 ended, TMOD was challenged to provide “world-class” data and mission su

port for an ever-increasing number of missions in the face of the essentially fixed budg

shown in the graphic.

To meet this challenge over the following three to five years, Squibb established a s

of five goals for TMOD:

• increase data return capacity by a factor of 2.6, 

• accomplish a significant portion of TMOD work through interaction with at least 1

strategic partners within five years,

• improve TMOD’s performance by capturing all of the data available from space mission

62

The Deep Space Network as an Organization in Change

Figure 9-19. TMOD primary challenge, 1997.
• complete the transformation of TMOD into an organization that provides a full Missio

Operations Services system, and

• reinvest operations costs savings into technology and development that will yield fu

ther cost and performance improvement.

Together with a metric to measure progress and a strategy for action, the goals wou

form the core of TMOD implementation planning for the years ahead. 

With these goals and their enabling technology accomplished, Squibb expected TMO

to not only survive in a realistic new budget environment, but also to move forwar

as a vital element of the NASA Strategic Plan, into the new millennium. He put h

expectations this way: “In the foreseeable future, the world will witness technologic

advances that will dwarf those of the past. Before long, our culture will embrace a

understanding of the universe that includes, among other things, its origins, evolutio

and destiny, the distribution and character of planets around the stars, and occurren

or prevalence of life in those environments. I fully expect the people of TMOD to b

among the leaders and innovators who will make these things happen.” It was a cle

and ringing challenge to the people of the DSN, the engineers and scientists, techn

cians and administrators, and supervisors and managers at all levels who composed i

vital essence. The measure of their response and the record of what they acheived wa

of necessity, a task for future historians of NASA’s Deep Space Network.

626

Uplink-Downlink: A History of the Deep Space Networ
Endnotes

1. William R. Corliss, “A History of the Deep Space Network,” NASA CR-15191

(Washington, DC: NASA, 1976).

2. J. Bluth, personal communication with author, 22 June 1998.

3. Homer E. Newell, Beyond the Atmosphere, NASA SP-4211 (Washington, DC

NASA, 1980). 

4. Clayton R. Koppes, JPL and the American Space Program; A History of the J

Propulsion Laboratory (New Haven and London: Yale University Press, 1982).

5. R. Cargill Hall, Lunar Impact: A History of Project Ranger, NASA SP-421

(Washington, DC: NASA, 1977).

6. William R. Corliss, “History of the Deep Space Network,” NASA CR-15191

(Washington, DC: NASA, 1976).

7. D. J. Mudgway, “Viking Mission Support,” JPL Technical Report TR 32-1526, Vo

X (15 August 1972), pp. 22–26.

8. A. J. Siegmeth, “Pioneer 10 and G Mission Support,” JPL Technical Report TR 3

1526, Vol. X (15 August 1972), pp. 27–34.

9. M. J. Alazard, A. I. Beers, and T. D. Linnick, “Multimission Operations System

Office User Guide,” JPL Document D-9661 (15 June 1993).

10. Jet Propulsion Laboratory, “JPL Strategic Plan,” JPL Document 400-549 (Apr

1995); see also http://www.jpl.nasa.gov/stratplan/.

11. Michael Hammer and James Champy, Reengineering the Corporation (New Yor

Harper Collins, 1993).

12. R. J. Amorose, “Reengineering Team for Services Fulfillment (Operations); Fin

Report,” TMOD internal memorandum, RJA: 95-008 (14 March 1995).

62

The Deep Space Network as an Organization in Change
13. Gael F. Squibb, “Bridging the Space Frontier: TMOD Implementation Pla

FY 98” (Pasadena: Jet Propulsion Laboratory, 30 January 1998); see al

http://deepspace.jpl.nasa.gov/920/public/922_strat_plan/.

14. National Space Policy 1996; see also http://www.whitehouse.gov/WH/EOP/OSTP

NSTC/html/fs/fs-5.html.

15. Space Operations Management Office, “Space Operations Implementation Plan

Draft E,” (Houston : JSC, August 1997).

16. “NASA Strategic Plan,” NASA Policy Directive (NPD)-1000.1; see als

http://www.hq.nasa.gov/office/nsp/NSPTOC.html.

628

Uplink-Downlink: A History of the Deep Space Networ
LIST OF FIGURES

Figures, Introduction

1. Figure Intro-1. Voyager 1 outward bound for Jupiter, September 1977.

2. Figure Intro-2. Voyager 1 views Jupiter, February 1979.

3. Figure Intro-3. Mean distances of the terrestrial planets from the Sun.

4. Figure Intro-4. Mean distances of the Jovian planets from the Sun.

5. Figure Intro-5. HA-Dec and Az-El mounted antennas of the DSN.

6. Figure Intro-6. Injection into interplanetary orbit.

7. Figure Intro-7. Cassegrain focus antenna.

8. Figure Intro-8. Improvement in DSN downlink performance during the first

twenty years.

9. Figure Intro-9. An essential part of the answer; global map of the Deep Space

Network, 1992.

Figures, Chapter 1

1. Figure 1-1. View of the Pioneer tracking station site, Goldstone, California, 1978.

2. Figure 1-2. Prominent personalities of the Deep Space Network unveiling the

commemorative plaque at the Goldstone Pioneer Site, 28 October 1978.

3. Figure 1-3. The 26-meter antenna and tracking station (DSIF 11) at Pioneer site

Goldstone, California, 1958.

4. Figure 1-4. Essential features of the Project Echo Experiment, 1960

62
5. Figure 1-5. Az-El transmitting antenna for the Echo Balloon Experiment,

Goldstone, 1960.

6. Figure 1-6. The 26-meter antenna and tracking station (DSIF 41), Woomera,

Australia, 1961. 

7. Figure 1-7. The 26-meter antenna and tracking station (DSIF 51),

Hartebeestpoort, South Africa, 1961.

Figures, Chapter 2

1. Figure 2-1. World view of the Deep Space Instrumentation Facility, 1961.

2. Figure 2-2. Flight operations control center, JPL, 1961.

3. Figure 2-3. First close-up picture of Mars. Returned from Mariner 4 on 14 July

1965. 

4. Figure 2-4. Network Operations Control Center (NOCC) at JPL, 1969. 

5. Figure 2-5. Side elevation of the Goldstone 64-meter azimuth-elevation antenna,

1966.

6. Figure 2-6. The 64-meter antenna at Goldstone, 1966.

7. Figure 2-7. Composition of the Deep Space Network, 1974.

Figures, Chapter 3

1. Figure 3-1. The Viking Era mission set.

2. Figure 3-2. Functional block diagram of the DSN, 1978. 

3. Figure 3-3. Heliocentric orbit of Helios 1.

630

Uplink-Downlink: A History of the Deep Space Networ
4. Figure 3-4. Configurations of the Viking Orbiter (top) and Viking Lander (bottom)

5. Figure 3-5. Viking Orbiter, Lander, Earth Telecommunications System.

6. Figure 3-6. First Viking close-up picture of Mars surface.

7. Figure 3-7. First panoramic picture of the surface of Mars.

8. Figure 3-8. Voyager trajectories to Jupiter, Saturn, and Uranus.

9. Figure 3-9. Downlink performance estimates for Pioneers 10 and 11.

10. Figure 3-10. Functional block diagram of the DSN Mark III-75 configuration fo

64-meter stations.

11. Figure 3-11. Functional block diagram of the DSN Mark III-75 configuration fo

26-meter stations.

12. Figure 3-12. Hydrostatic bearing and ball joint assembly.

13. Figure 3-13. Mark III-77 Network systems and subsystems.

14. Figure 3-14. General configuration of the DSN Mark III-77 Network. 

15. Figure 3-15. DSN Mark III Data System implementation schedule, 1977.

16. Figure 3-16. Basic organization of the Mark III Data System.

17. Figure 3-17. Functional block diagram of the Mark III-77 Telemetry System.

18. Figure 3-18. DSN Mark III Command System, 1978.

19. Figure 3-19. DSN-GCF-NASCOM ground communications, 1976–78.

20. Figure 3-20. Structural changes to the 26-meter antenna for extension to 34-mete

diameter.

21. Figure 3-21. Goldstone Station, DSS 12 antenna after conversion to 34-meter, SX-band configuration, October 1978. 

63

List of Figures
Figures, Chapter 4

1. Figure 4-1. Voyager Era Deep Space mission set, 1977–86.

2. Figure 4-2. Voyager 1 image of Jupiter, 13 February 1979, at a distance of 20 millio

kilometers, showing Io (left) and Europa (right) against the Jupiter cloud tops. 

3. Figure 4-3. Voyager 1 image of Io, 4 March 1979. 

4. Figure 4-4. Voyager 1 trajectory through the Jupiter system, 5 March 1979. 

5. Figure 4-5. Voyager 1 image of Saturn and its rings, August 1980. 

6. Figure 4-6. Voyager 1 image of Saturn and its rings, November 1980. 

7. Figure 4-7. Parkes 64-m radio astronomy antenna. 

8. Figure 4-8. Enhanced link performance for Voyager 2 at Uranus. 

9. Figure 4-9. Functional block diagram of the Parkes-CDSCC telemetry array for

Voyager Uranus Encounter, January 1986. 

10. Figure 4-10. Pictorial diagram of the Voyager 2 mission. 

11. Figure 4-11. Voyager 2 image of the Uranus satellite Miranda. 

12. Figure 4-12. Pioneer 10 and 11 heliocentric trajectories, September 1979. 

13. Figure 4-13. DSN configuration for ICE encounter of comet Giacobini-Zinner, 

11 September 1985. 

14. Figure 4-14. 34-meter high efficiency (HEF) antenna: DSS 15, Goldstone. 

15. Figure 4-15. Rehabilitation of the DSS 14 hydrostatic bearing and pedestal

concrete, June 1983–June 1984. 

16. Figure 4-16. Work in progress on the 60-m to 70-m antenna extension at DSS 14

Goldstone, December 1987. 

632

Uplink-Downlink: A History of the Deep Space Networ
17. Figure 4-17. Elements of the DSN and GSTDN, 1982. 

18. Figure 4-18. Canberra Deep Space Communications Complex, January 1985. 

19. Figure 4-19. Deep Space Network, Mark IVA configuration. 

20. Figure 4-20. DSN antenna operations costs, 1980–2000. 

21. Figure 4-21. Signal Processing Center, Mark IVA configuration. 

22. Figure 4-22. Network Operations Control Center, Mark IVA. 

23. Figure 4-23. Principal features of the DSCC Mark IVA Telemetry Subsystem. 

24. Figure 4-24. Functional block diagram of the Mark IVA Baseband Assembly (BBA)

25. Figure 4-25. DSN Mark IVA Telemetry System key characteristics. 

26. Figure 4-26. DSN Command System Mark IVA 1985. 

Figures, Chapter 5

1. Figure 5-1. Galileo Era Deep Space mission set. DJM files.

2. Figure 5-2. Phobos L-band feedhorn mounted on the 64-m antenna.

3. Figure 5-3. Magellan Venus Orbit mapping profile.

4. Figure 5-4. Diagram of Magellan spacecraft in cruise configuration.

5. Figure 5-5. Magellan SAR image of an impact crater in the Atalanta Region of Venu

6. Figure 5-6. Encounter geometry for Voyager 2 at Neptune.

7. Figure 5-7. Voyager 2 views three most prominent features of Neptune.

8. Figure 5-8. Voyager 2 views south polar cap of Triton.

63

List of Figures
9. Figure 5-9. Voyager 2 views Neptune and Triton. 

10. Figure 5-10. The Galileo Venus-Earth-Earth-Gravity-Assist (VEEGA) trajectory.

11. Figure 5-11. The Galileo spacecraft cruise configuration.

12. Figure 5-12. The Galileo Orbiter and Probe arrival at Jupiter, 7 December 1995.

13. Figure 5-13. Network configuration for Galileo launch and cruise, 1989.

14. Figure 5-14. Galileo 1989 VEEGA mission: predicted X-band downlink

performance at Jupiter arrival: 7 December 1995.

15. Figure 5-15. Geometry of the Galileo first Earth flyby.

16. Figure 5-16. Galileo image of Earth: Antarctica. 

17. Figure 5-17. Earth and Moon from Galileo, December 1992.

18. Figure 5-18. Asteroid Ida and its moon.

19. Figure 5-19. The DSN in full array configuration for Galileo Jupiter orbital

operations.

20. Figure 5-20. Full DSN array operations for Galileo: typical downlink data rate profil

21. Figure 5-21. Galileo image of icebergs on the surface of Europa.

22. Figure 5-22. Ulysses solar polar trajectory.

23. Figure 5-23. The Ulysses spacecraft inflight configuration.

24. Figure 5-24. Ulysses second solar polar orbit.

25. Figure 5-25. Cracked bearing rollers and inner race: DSS 63, December 1989.

26. Figure 5-26. Twenty years of telemetry arraying in the DSN.

27. Figure 5-27. Parkes-CDSCC telemetry array.

634

Uplink-Downlink: A History of the Deep Space Networ
28. Figure 5-28. Enhanced downlink performance at Uranus. 

29. Figure 5-29. Enhanced downlink performance at Neptune. 

30. Figure 5-30. VLA-GDSCC telemetry array.

31. Figure 5-31. The concept of DSN telemetry for the Galileo LGA mission.

32. Figure 5-32. Functional diagram of the DSN Galileo telemetry subsystem for the

Canberra Deep Space Communications Complex.

33. Figure 5-33. Beam waveguide antenna in conceptual form.

34. Figure 5-34. Design for 34-meter beam waveguide antenna at DSS 13. 

35. Figure 5-35. Design for operational 34-meter beam waveguide antenna.

36. Figure 5-36. DSS 34 beam waveguide antenna at Canberra Deep Space

Communications Complex, Australia, 1996.

37. Figure 5-37. Cluster of three 34-m beam waveguide antennas at Goldstone, 1995

38. Figure 5-38. Signal Processing Center configuration, 1993.

39. Figure 5-39. DSCC Telemetry Subsystem, 1997. 

40. Figure 5-40. DSCC Command System, 1996. 

41. Figure 5-41. DSCC Tracking Subsystem, 1995.

42. Figure 5-42. Ground Communications Facility, 1992.

Figures, Chapter 6

1. Figure 6-1. Cassini Era mission set, 1997.

2. Figure 6-2. Mars Global Surveyor spacecraft in the mapping configuration.

63

List of Figures
3. Figure 6-3. DSN configuration for Mars Global Surveyor.

4. Figure 6-4. Mars Global Surveyor image of Olympus Mons.

5. Figure 6-5. Pathfinder Lander deployed on surface of Mars.

6. Figure 6-6. The MPF Lander camera views the Sojourner Rover in operation nea

Yogi Rock on the Surface of Mars, July 1997.

7. Figure 6-7. Cassini interplanetary trajectory.

8. Figure 6-8. Cassini spacecraft with Huygens Probe.

9. Figure 6-9. Location identifiers for DSN and related sites.

10. Figure 6-10. Goldstone Deep Space Communications Complex, 1997.

11. Figure 6-11. Canberra Deep Space Communications Complex, 1997.

12. Figure 6-12. Madrid Deep Space Communications Complex, 1997.

13. Figure 6-13. OVLBI Subnetwork functional block diagram. 

14. Figure 6-14. DSS 23: SVLBI 11-meter antenna at Goldstone, 1996.

Figures, Chapter 7

1. Figure 7-1. Deep Space Communications Complex in Canberra, Australia.

2. Figure 7-2. An early parabolic design of a 26-meter antenna.

3. Figure 7-3. The quasi-parabolic 34-meter high-efficiency antenna, DSS 15.

4. Figure 7-4. A 70-meter antenna with dual-shape reflector design.

5. Figure 7-5. A 34-meter beam waveguide antenna at Goldstone Technology

Development Site, DSS 13.

636

Uplink-Downlink: A History of the Deep Space Networ
6. Figure 7-6. Stationary equipment room below BWG antenna.

7. Figure 7-7. Dichroic (frequency-selective) reflector developed under Advanced

Systems Program.

8. Figure 7-8. Ultra-low noise amplifier (ULNA) at DSS 13.

9. Figure 7-9. High-electron mobility transistor (HEMT) low-noise microwave

amplifier.

10. Figure 7-10. Advanced Receiver (ARX) used to track the Pioneer 10 spacecraft.

11. Figure 7-11. Telemetry communication channel performance for various coding

schemes.

12. Figure 7-12. The 64-m antenna of the Radio Astronomy Observatory, Parkes,

Australia.

13. Figure 7-13. The Very Large Array (VLA) of the National Radio Astronomy

Observatory (NRAO) at Socorro, New Mexico.

14. Figure 7-14. The new linear ion trap (LIT) frequency standard.

15. Figure 7-15. First high-resolution radar image of Venus.

16. Figure 7-16. Profile of deep space telecommunications capability, 1960–2020. 

Figures, Chapter 8

1. Figure 8-1. DSN science-related publications, 1962–97. 

2. Figure 8-2. Real-time bandwidth reduction in the radio science Occultation Data

Assembly. 

3. Figure 8-3. Characteristic three-pulse signature of a gravitational wave in two-way

Doppler data. 

63

List of Figures
4. Figure 8-4. Detection strategy and system configuration for the SETI sky survey

field tests, 1985.

5. Figure 8-5. SETI detection of spacecraft signals, 1985.

6. Figure 8-6. The first HRMS sky survey, Goldstone, 12 October 1992. 

7. Figure 8-7. Project ARIES transportable antenna interferometer system.

8. Figure 8-8. Global Positioning System, 1986.

9. Figure 8-9. Schematic view of GPS-based ionospheric calibration.

10. Figure 8-10. Functional block diagram of the Venus radar, 1962.

11. Figure 8-11. High Speed Data Acquisition System for the Goldstone Radar, 1984

12. Figure 8-12. Relative sensitivity for the Goldstone Radar antenna.

13. Figure 8-13. Goldstone Solar System Radar images of Asteroid Toutatis, 1992.

14. Figure 8-14. Goldstone Radar astronomy publications, 1988–97.

Figures, Chapter 9 

1. Figure 9-1. NASA Office of Space Flight Development, 1959–61.

2. Figure 9-2. Telecommunications Division at JPL, 1961–62.

3. Figure 9-3. JPL organization, 1964.

4. Figure 9-4. NASA organization for the Office of Tracking and Data Acquisition,

1961.

5. Figure 9-5. The Deep Space Network established, December 1963. 

638

Uplink-Downlink: A History of the Deep Space Networ
6. Figure 9-6. Organization for Tracking and Data Acquisition support at JPL,

October 1964.

7. Figure 9-7. Organization of the technical divisions after the transfer of the SFOF

to OCIS, 1972.

8. Figure 9-8. Functional interfaces between the DSN and the SFOF for Viking,

1972.

9. Figure 9-9. TDA Office 400 organization at JPL, 1978.

10. Figure 9-10. TDA Office 400 organization at JPL, 1980–87. 

11. Figure 9-11. National Aeronautics and Space Administration, 1991

12. Figure 9-12. Multimission Operations Systems Office (440), 1993. 

13. Figure 9-13. NASA Space Communications and Operations Program. 

14. Figure 9-14. Telecommunications and Mission Operations Directorate, 1996. 

15. Figure 9-15. Predicted cost and savings for reengineering TMOD Services

Fulfillment Processes.

16. Figure 9-16. Data Capture road map.

17. Figure 9-17. Telecommunications and Mission Operations Directorate, 1997. 

18. Figure 9-18. Organization of the National Aeronautics and Space Administration

1996. 

19. Figure 9-19. TMOD primary challenge, 1997.

63

List of Figures
APPENDIX

Further Reading for Specialists

The history of technology in the Deep Space Network is well documented in a contin

ous series of technical articles published in the JPL Space Programs Summaries and i

successor journals. Most of these articles describe work that was funded exclusively by th

DSN Advanced Systems Program or was funded in cooperation with other DSN program

related to engineering implementation or mission operations. This appendix will provid

the specialist reader with an overview of key developments in areas of specific interest. 

Most of the citations that follow were extracted from the online index to “The Dee

Space Network Progress Report” and its subsequent names, for issues from 1970 an

later, or from the author index to earlier reports. The list also includes a number of cit

tions from refereed external technical journals and several case studies of advance

technology in the DSN.

The early JPL Space Programs Summary (SPS) was published as a five-volume set de

ignated as SPS 37-nn. One of these volumes, Volume IV, covered all Supporting Researc

and Advanced Development activities at JPL, including the Deep Space Instrumentatio

Facility (DSIF) Advanced Systems Program. Implementation and Operations activiti

were included in Volume III.

The Space Programs Summary became a four-volume set with SPS- 37-47. All Supportin

Research and Advanced Development activities are contained in Volume III, and a

DSN activity is described in Volume II.

Publication of the Space Program Summaries ceased in 1970 with SPS 37-66. Howeve

the publication of progress reports for the DSN (including the DSN Advanced System

Program) were continued in a series of JPL Technical Reports beginning with JPL-T

32-1526, Volume I (15 February 1971). The DSN continued to report its progress 

this form through TR 32-1526, Volume XIX (15 February 1974), when the name becam

“The Deep Space Network Progress Report,” DSN-PR 42-nn. 

DSN progress reports under the new title began with DSN-PR 42-20 in April 197

and, except for the substitution of “Telecommunications and Data Acquisition” for “Dee

Space Network” in June 1980 (TDA PR 42-57), followed by “Telecommunications an

Mission Operations” in 1998, the series continued without further change through th

end of the century.

64
For ease of identification, the appendix refers to these various publications as JPL-SP

JPL-TR, and TDA-PR. Copies of these documents may be obtained from the Jet Propulsio

Laboratory, Pasadena, California. Articles that are referenced in issues TDA-PR 42-6

and later may be accessed online at http://tmo.jpl.nasa.gov/progress_report.

1. The evolution of technology in the Deep Space Network.

Layland, J. W., and L. L. Rauch. “The Evolution of Technology in the Deep Spa

Network, A History of the Advanced Systems Program,” TDA Progress Report PR 4

130, April-June 1997, 15 August 1997.

2. The great antennas of the DSN. 

Potter, P. D. “Improved Dichroic Reflector Design for the 64-m Antenna S- and X

band Feed Systems,” JPL-TR 32-1526, Vol. XIX: November and December 1973, 1

February 1974, pp. 55–62.

Potter, P. D. “Shaped Antenna Designs and Performance for 64-m Class DSN Antennas

DSN-PR 42-20: January-February 1974, 15 April 1974, pp. 92–111.

Galindo-Israel, V., N. Imbriale, Y. Rahmat-Samii, and T. Veruttipong. “Interpolatio

Methods for GTD Analysis of Shaped Reflectors,” TDA Progress Report PR 42-8

October-December 1984, 15 February 1985, pp. 62–67.

Goodwin, J. P. “Usuda Deep Space Center Support for ICE,” TDA Progress Report P

42-84: October-December 1985, 15 February 1986, pp. 186–96. 

Fanelli, N. A., J. P. Goodwin, S. M. Petty, T. Hayashi, T. Nishimura, and T. Takan

“Utilization of the Usuda Deep Space Center for the United States International Cometa

Explorer (ICE).” Proceedings of the Fifteenth International Symposium on Spa

Technology and Science, Tokyo, Japan, 1986.

Otoshi, T. Y., and M. M. Franco. “Dual Passband Dichroic Plate for X-band,” TD

Progress Report PR 42-94: April-June 1988, 15 August 1988, pp. 110–34.

Chen, J. C., P. H. Stanton, and H. F. Reilly. “Performance of the X-/Ka-/KABLE-ban

Dichroic Plate in the DSS 13 Beam Waveguide Antenna,” TDA Progress Report P

42-115: July-September 1993, 15 November 1994, pp. 54–64.

642

Uplink-Downlink: A History of the Deep Space Networ
Rafferty, William, Stephen D. Slobin, and Charles T. Stelzried. “Ground Antennas 

NASA’s Deep Space Telecommunications.” Proceedings of the Institute of Electrical an

Electronics Engineers, Vol. 82, No. 5, May 1994.

3. Forward command/data link (uplink).

Benjauthrit, B., and T. K. Truong. “Encoding and Decoding a Telecommunication Standa

Command Code,” DSN Progress Report PR 42-38: January and February 1977, 15 Ap

1977, pp. 115–19. 

4. Return telemetry/data link (downlink).

Clauss, R. C., and R. B. Quinn. “Low Noise Receivers: Microwave Maser Development

JPL Technical Report TR 32-1526, Vol. IX: March and April 1972, 15 June 1972, pp. 128–3

Clauss, R. C., and E. Wiebe. “Low-Noise Receivers: Microwave Maser Development

JPL Technical Report TR 32-1526, Vol. XIX: November and December 1973, 15 Februa

1974, pp. 93–99.

Ulvestad, J. S., G. M. Resch, and W. D. Brundage (National Radio Astronomy Observator

New Mexico). “X-band System Performance of the Very Large Array,” TDA Progre

Report PR 42-92: October-December 1987, 15 February 1988, pp. 123–37.

Shell, J., and D. Neff. “A 32-GHz Reflected-Wave Maser Amplifier With Wide Instantaneo

Bandwidth,” TDA Progress Report PR 42-94: April-June 1988, 15 August 1988, pp. 145–6

Tanida, L. “An 8.4-GHz Cryogenically Cooled HEMT Amplifier for DSS 13,” TD

Progress Report PR 42-94: April-June 1988, 15 August 1988, pp. 163–69.

Bautista, J. J., G. G. Ortiz, K. H. G. Duh (GE Electronics Laboratory, New York

W. F. Kopp (GE Electronics Laboratory, New York), P. Ho (GE Electronics Laborator

New York), P. C. Chao (GE Electronics Laboratory, New York), M. Y. Kao (GE Electroni

Laboratory, New York), P. M. Smith (GE Electronics Laboratory, New York), an

J. M. Ballingall (GE Electronics Laboratory, New York). “32-GHz Cryogenically Coole

HEMT Low-Noise Amplifiers,” TDA Progress Report PR 42-95: July-September 198

15 November 1988, pp. 71–81.

64

Appendix
Glass, G. W., G. G. Ortiz, and D. L. Johnson. “X-band Ultralow-Noise Maser Amplifi

Performance,” TDA Progress Report PR 42-116, October-December 1993, 15 Februa

1994, pp. 246–53.

Shell, J., and R. B. Quinn. “A Dual-Cavity Ruby Maser for the Ka-band Link Experiment

TDA Progress Report PR 42-116, October-December 1993, 15 February 1994, pp. 53–7

5. Phase-lock tracking.

Jaffe, R., and E. Rechtin. “Design and Performance of Phase-Lock Circuits Capable 

Near-Optimum Performance over a Wide Range of Input Signal and Noise Level,” IR

Trans. Information Theory, Vol. IT-1, March 1955, pp. 66–76.

Tausworthe, R. C. “Another Look at the Optimum Design of Tracking Loops,” JPL

SPS 37-32, Vol. IV, 30 April 1965, pp. 281–83. 

Lindsey, W. C. “The Effect of RF Timing Noise in Two-Way Communications Systems

JPL-SPS 37-32, Vol. IV, 30 April 1965, pp. 284–88.

Lindsey, W. C. “Optimum Modulation Indices for Single Channel One Way & Tw

Way Coherent Communications,” JPL-SPS 37-37, Vol. IV, 28 February 1966, pp. 287–9

Lindsey, W. C., and R. C. Tausworthe. “Digital Data Transition Tracking Loops,” JPL

SPS 37-50, Vol. III, 30 April 1968, pp. 272–76.

Tausworthe, R. C. “Efficiency of Noisy Reference Detection,” JPL-SPS 37-54, Vol. II

31 December 1968, pp. 195–201.

Tausworthe, R. C. “Theory and Practical Design of Phase-Locked Receivers,” JPL Technic

Report TR 32-819, 27 April 1971.

Layland, J. W. “Noisy Reference Effects on Multiple-Antenna Reception,” DSN Progre

Report PR 42-25, November and December 1974, 15 February 1975, pp. 60–64.

6. Synchronization and detection.

Baumgartner, W. S., W. Frey, M. H. Brockman, R. W. Burt, J. W. Layland, G. M. Munso

N. A. Burow, L. Couvillon, A. Vaisnys, R. G. Petrie, C. T. Stelzried, and J. K. Wo

“Multiple-Mission Telemetry System,” JPL-SPS 37-46, Vol. III, July 1967, pp. 175–24

644

Uplink-Downlink: A History of the Deep Space Networ
Tausworthe, R. C., et al. “High Rate Telemetry Project,” JPL-SPS 37-54, Vol. II, 3

November 1968, pp. 71–81.

Simon, M., and A. Mileant. “DSA’s Subcarrier Demodulation Losses,” TDA Progre

Report PR 42-85: January-March 1986, 15 May 1986, pp. 111–17.

Doerksen, I., and L. Howard. “Baseband Assembly Analog-to-Digital Converter Board

TDA Progress Report PR 42-93: January-March 1988, 15 May 1988, pp. 257–64.

7. Digital receivers.

Kumar, R., and W. J. Hurd. “A Class of Optimum Digital Phase Locked Loops for th

DSN Advanced Receiver,” TDA Progress Report PR 42-83: July-September 1985, 1

November 1985, pp. 63–80.

Brown, D. H., and W. J. Hurd. “DSN Advanced Receiver: Breadboard Description an

Test Results,” TDA Progress Report PR 42-89: January-March 1987, 15 May 1987, p

48–66.

Hinedi, S. “A Functional Description of the Advanced Receiver,” TDA Progress Repo

PR 42-100: October-December 1989, 15 February 1990, pp. 131–49.

Hinedi, S., R. Bevan, and M. Marina. “The Advanced Receiver II: Telemetry Test Resul

in CTA 21,” TDA Progress Report PR 42-104: October-December 1990, 15 Februa

1991, pp. 140–56.

Sadr, R., R. Bevan, and S. Hinedi. “The Advanced Receiver II Telemetry Test Resul

at Goldstone,” TDA Progress Report PR 42-106: April-June 1991, 15 August 1991, p

119–31.

8. Encoding and decoding.

Stiffler, J. J. “Instantly Synchronizable Block Code Dictionaries,” JPL-SPS 37-32, Vo

IV, 30 April 1965, pp. 268–72.

Stiffler, J. J., and A. J. Viterbi. “Performance of a Class of Q-Orthogonal Signals f

Communication over the Gaussian Channel,” JPL-SPS 37-32, Vol. IV, 30 April 196

pp. 277–81.

64

Appendix
Green, R. R. “A Serial Orthogonal Decoder,” JPL-SPS 37-39, Vol. IV, 30 June 196

pp. 247–52.

Lushbaugh, W. A., and J. W. Layland. “System Design of a Sequential Decoding Machine

JPL-SPS 37-50, Vol. II, 31 March 1968, pp. 71–78.

McEleice, R. J., and J. W. Layland. “A Upper Bound to the Free Distance of a Tr

Code,” JPL-SPS 37-62, Vol. III, 30 April 1970, pp. 63–64.

Layland, J. W. “Performance of Short Constraint Length Convolutional Codes and 

Heuristic Code Construction Algorithm,” JPL-SPS 37-64, Vol. II, August 1970.

Lushbaugh, W. A. “Information Systems: Hardware Version of an Optimal Convolution

Decoder,” JPL Technical Report TR 32-1526, Vol. II: January and February 1971, 1

April 1971, pp. 49–55.

Butman, S. A., L. J. Deutsch, and R. L. Miller. “Performance of Concatenated Cod

for Deep Space Missions,” TDA Progress Report PR 42-63: March and April 1981, 1

June 1981, pp. 33–39.

Divsalar, D., and J. H. Yuen. “Performance of Concatenated Reed-Solomon/Viterbi Chann

Coding,” TDA Progress Report PR 42-71: July-September 1982, 15 November 198

pp. 81–94.

Yuen, J. H., and Q. D. Vo. “In Search of a 2-dB Coding Gain,” TDA Progress Repo

PR 42-83: July-September 1985, 15 November 1985, pp. 26–33.

Dolinar, S. J. “A New Code for Galileo,” TDA Progress Report PR 42-93: Januar

March 1988, 15 May 1988, pp. 83–96.

Dolinar, S. J. “VLA Telemetry Performance With Concatenated Coding for Voyager 

Neptune,” TDA Progress Report PR 42-95: July-September 1988, 15 November 198

pp. 112–33.

Statman, J., G. Zimmerman, F. Pollara, and O. Collins. “A Long Constraint Leng

VLSI Viterbi Decoder for the DSN,” TDA Progress Report PR 42-95: July-Septemb

1988, 15 November 1988, pp. 134–42. 

646

Uplink-Downlink: A History of the Deep Space Networ
Divsalar, D., M. K. Simon, and J. H. Yuen. “The Use of Interleaving for Reducin

Radio Loss: Convolutionally Coded Systems,” TDA Progress Report PR 42-96: Octobe

December 1988, 15 February 1989, pp. 21–39.

Collins, O., F. Pollara, S. J. Dolinar, and J. Statman. “Wiring Viterbi Decoders (Splittin

deBruijn Graphs),” TDA Progress Report PR 42-96: October-December 1988, 15 Februa

1989, pp. 93–103.

Berrou, C., A. Glavieux, and P. Thitimajshima. “Near Shannon Limit Error-Correctin

Coding and Decoding: Turbo Codes,” ICC, 1993, pp. 1064–70.

Divsalar, D. and F. Pollara. “On the Design of Turbo Codes,” TDA Progress Report P

42-123, July-September 1995, 15 November 1995, pp. 99–121. 

Benedetto, S., Divsalar, D., et al. “Serial Concatenation of Interleaved Codes; Performan

Analysis, Design, and Iterative Decoding,” IEEE Transactions on Information Theor

Volume 44, 1998, p. 909.

9. Data compression. 

Cheung, K. M., F. Pollara, and M. Shahshahani. “Integer Cosine Transform for Imag

Compression,” TDA Progress Report PR 42-105: January-March 1991, 15 May 199

pp. 45–53.

Ekroot, L., S. J. Dolinar, and K. M. Cheung. “Integer Cosine Transform Compressio

for Galileo at Jupiter: A Preliminary Look,” TDA Progress Report PR 42-115, Jul

September 1993, 15 November 1994, pp. 110–23.

10. Arraying of antennas.

Urech, J. M. “Telemetry Improvement Proposal for the 85-foot Antenna Network

Space Programs Summary 37-63, Vol. II, Jet Propulsion Laboratory, Pasadena, Californi

31 May 1970. 

Urech, J. M. “Processed Data Combination for Telemetry Improvement at DSS 62

JPL Technical Report TR 32-1526, Vol. II: January and February 1971, 15 April 197

pp. 169–76. 

64

Appendix
Wilck, H. “A Signal Combiner for Antenna Arraying,” DSN Progress Report PR 4

25, November and December 1974, 15 February 1975, pp. 111–17.

Winkelstein, R. A. “Analysis of the Signal Combiner for Multiple Antenna Arraying

DSN Progress Report PR 42-26, January and December 1975, 15 April 1975, p

102–18. 

Stevens, R. “Applications of Telemetry Arraying in the DSN,” TDA Progress Report P

42-72: October-December 1982, 15 February 1983, pp. 78–82.

Layland, J. W., and D. W. Brown. “Planning for VLA/DSN Arrayed Support to th

Voyager at Neptune,” TDA Progress Report PR 42-82: April-June 1985, 15 Augu

1985, pp. 125–35.

Brown, D. W., W. D. Brundage, J. S. Ulvestad, S. S. Kent, and K. P. Bartos. “Interagen

Telemetry Arraying for Voyager-Neptune Encounter,” TDA Progress Report PR 42-10

April-June 1990, 15 August 1990, pp. 91–118.

Bartok, C. D. “Performance of the Real-Time Array Signal Combiner During the Voyag

Mission,” TDA Progress Report PR 42-63: March-April 1981, 15 June 1981, pp. 191–20

Layland, J. W. “ICE Telemetry Performance,” TDA Progress Report PR 42-84: Octobe

December 1985, 15 February 1986, pp. 203–13.

Hurd, W. J., F. Pollara, M. D. Russell, B. Siev, and P. U. Winter. “Intercontinent

Antenna Arraying by Symbol Stream Combining at ICE Giacobini-Zinner Encounter

TDA Progress Report PR 42-84: October-December 1985, 15 February 1986, pp. 220–2

Foster, C., and M. Marina. “Analysis of the ICE Combiner for Multiple Antenna Arraying

TDA Progress Report PR 42-91: July-September 1987, 15 November 1987, pp. 269–7

Brown, D. W., W. D. Brundage (National Radio Astronomy Observatory), J. S. Ulvesta

S. S. Kent, and K. P. Bartos. “Interagency Telemetry Arraying for Voyager-Neptun

Encounter,” TDA Progress Report PR 42-102: April-June 1990, 15 August 1990, p

91–118.

Rogstad, D. H. “Suppressed Carrier Full-Spectrum Combining,” TDA Progress Repo

PR 42-107: July-September 1991, 15 November 1991, pp. 12–20.

648

Uplink-Downlink: A History of the Deep Space Networ
11. Radio metrics—tools and techniques.

Titsworth, R. C. “Optimal Ranging Codes,” JPL Technical Report TR 32-411, 15 Ap

1963.

Hamilton, T. W., and W. G. Melbourne. “Information Content of a Single Pass 

Doppler Data from a Distant Spacecraft,” JPL-SPS 37-39, Vol. III, 31 May 1966, p

18–23.

Tausworthe, R. C. “Minimizing Range Code Acquisition Time,” JPL-SPS 37-42, Vo

IV, 31 December 1966, pp. 198–200.

Lushbaugh, W. L., and L. D. Rice. “Mariner Venus 67 Ranging System Digital Processin

Design,” JPL-SPS 37-50, Vol. II, 31 March 1968.

Goldstein, R. M. “Ranging with Sequential Components,” JPL-SPS 37-52, Vol. II, 3

July 1968, pp. 46–49.

Martin, W. L. “A Binary Coded Sequential Acquisition Ranging System,” JPL-SPS 3

57, Vol. II, 31 May 1969, pp. 72–81. 

Martin, W. L. “Performance of the Binary Coded Sequential Acquisition Ranging Syste

of DSS 14,” JPL-SPS 37-62, Vol. II, 31 March 1970, pp. 55–61.

Otoshi, T. Y. “S/X Experiment: A Study of the Effects of Ambient Temperature o

Ranging Calibrations,” DSN Progress Report PR 42-23, July and August 1974, 1

October 1974, pp. 45–51.

Otoshi, T. Y. “S/X Band Experiment: A Study of the Effects of Multipath on Two-W

Range,” DSN Progress Report PR 42-25, November and December 1974, 15 Februa

1975, pp. 69–83.

Melbourne, W. G. “Navigation Between the Planets,” Scientific American 234, no. 

(June 1976): 57–74.

Martin, W. L., and A. I. Zygielbaum. “Mu-II Ranging,” JPL-TM 33-768, 15 May 197

Layland, J. W., and A. I. Zygielbaum. “On Improved Ranging-II,” DSN Progress Repo

PR 42-50: January and February 1979, 15 April 1979, pp. 68–73. 

64

Appendix
Thurman, S. W. “Deep-Space Navigation With Differenced Data Types-Part I: Difference

Range Information Content,” TDA Progress Report PR 42-103: July-September 199

15 November 1990, pp. 47–60.

Thurman, S. W. “Deep-Space Navigation With Differenced Data Types-Part I

Differenced Doppler Information Content,” TDA Progress Report PR 42-103: Jul

September 1990, 15 November 1990, pp. 61–69.

Kahn, R. D., W. M. Folkner, C. D. Edwards, and A. Vijayaraghavan. “Positio

Determination of a Lander and Rover at Mars With Earth-Based Differential Tracking

TDA Progress Report PR 42-108: October-December 1991, 15 February 1992, pp. 279–9

12. Timing standards.

Finnie, D. “Frequency Generation and Control: Atomic Hydrogen Maser Frequen

Standard,” JPL Technical Report TR 32-1526, Vol. I: November and December 197

15 February 1971, pp. 73–75.

Dachel, P. R., S. M. Petty, R. F. Meyer, and R. L. Syndor. “Hydrogen Maser Frequen

Standards for the Deep Space Networks,” DSN Progress Report PR 42-40, May an

June 1977, 15 August 1977, pp. 76–83.

Prestage, J. D., G. J. Dick, and L. Maleki. “New Ion Trap for Atomic Frequency Standa

Applications,” TDA Progress Report PR 42-97: January-March 1989, 15 May 1989, p

58–63.

Prestage, J. D. “Improved Linear Ion Trap Physics Package,” TDA Progress Report P

42-113, January-March 1993, 15 May 1993, pp. 1–6.

13. Earth rotation and propagation media.

Winn, F. B. “Tropospheric Refraction Calibrations and Their Significance on Radi

Metric Doppler Reductions,” JPL Technical Report TR 32-1526, Vol. VII: Novemb

and December 1971, 15 February 1972, pp. 68–73.

Von Roos, O. H., and B. D. Mulhall. “An Evaluation of Charged Particle Calibratio

by a Two-Way Dual-Frequency Technique and Alternatives to This Technique,” JP

Technical Report TR 32-1526, Vol. XI: July and August 1972, 15 October 1972, p

42–52.

650

Uplink-Downlink: A History of the Deep Space Networ
Winn, F. B., S. R. Reinbold, K. W. Yip, R. E. Koch, and A. Lubeley. “Corruption 

Radio Metric Doppler Due to Solar Plasma Dynamics: S/X Dual-Frequency Doppl

Calibration for These Effects,” DSN Progress Report PR 42-30, September and Octob

1975, 15 December 1975, pp. 88–101. 

Slobin, S. D., and P. D. Batelaan. “DSN Water Vapor Radiometer- Tropospheric Rang

Delay Calibration,” DSN Progress Report PR 42-49: November and December 197

15 February 1979, pp. 136–45.

Roth, M., and T. Yunck. “VLBI System for Weekly Measurement of UTI and Pol

Motion: Preliminary Results,” TDA Progress Report PR 42-58: May and June 1980, 1

August 1980, pp. 15–20.

Sovers, O. J.; J. L. Fanselow; G. H. Purcell, Jr.; D. H. Rogstad; and J. B. Thoma

“Determination of Intercontinental Baselines and Earth Orientation Using VLBI,” TD

Progress Report PR 42-71: July-September 1982, 15 November 1982, pp. 1–7.

Scheid, J. A. “Comparison of the Calibration of Ionospheric Delay in VLBI Data b

the Methods of Dual Frequency and Faraday Rotation,” TDA Progress Report PR 4

82: April-June 1985, 15 August 1985, pp. 11–23. 

Lindquister, U. J., A. P. Freedman, and G. Blewitt. “A Demonstration of Centimete

Level Monitoring of Polar Motion With the Global Positioning System,” TDA Progre

Report PR 42-108: October-December 1991, 15 February 1992, pp. 1–9.

Linfield, R. P., and J. Z. Wilcox. “Radio Metric Errors Due to Mismatch and Offs

Between a DSN Antenna Beam and the Beam of a Troposphere Calibration Instrument

TDA Progress Report PR 42-114, April-June 1993, 15 August 1993, pp. 1–13.

14. Radio science.

Levy, G. S., and G. E. Wood. “Voyager-Jupiter Radio Science Data Papers,” TDA Progre

Report PR 42-58: May and June 1980, 15 August 1980, pp. 114–15.

Peng, T. K., and F. F. Donivan. “Deep Space Network Radio Science System for Voyag

Uranus and Galileo Missions,” TDA Progress Report PR 42-84: October-Decemb

1985, 15 February 1986, pp. 143–51.

65

Appendix
Nelson, S. J., and J. W. Armstrong. “Gravitational Wave Searches Using the DSN

TDA Progress Report PR 42-94: April-June 1988, 15 August 1988, pp. 75–85.

Kursinski, E. R,. and S. W. Asmar. “Radio Science Ground Data System for the Voyage

Neptune Encounter, Part I,” TDA Progress Report PR 42-105: January-March 199

15 May 1991, pp. 109–27. 

15. VLBI and radio astronomy.

Miller, J. K. “The Application of Differential VLBI to Planetary Approach Orb

Determination,” DSN Progress Report PR 42-40, May and June 1977, 15 August 197

pp. 84–90.

Moultrie, B., T. H. Taylor, and P. J. Wolff. “The Performance of Differential VLBI Del

During Interplanetary Cruise,” TDA Progress Report PR 42-79, July-September 198

15 November 1984, pp. 35–46.

Ulvestad, J. S., and R. P. Linfield. “The Search for Reference Sources for VLBI Navigatio

of the Galileo Spacecraft,” TDA Progress Report PR 42-84, October-December 198

15 February 1986, pp. 152–63.

Satorius, E. H., M. J. Grimm, G. A. Zimmerman, and H. C. Wilck. “Finite Wordleng

Implementation of a Megachannel Digital Spectrum Analyzer,” TDA Progress Repo

PR 42-86, April- June 1986, 15 August 1986, pp. 244–54.

Quirk, M. P. (Institute for Defense Analyses, New Jersey), H. C. Wilck, M. F. Garyante

and M. J. Grimm. “A Wideband, High-Resolution Spectrum Analyzer,” TDA Progre

Report PR 42-93, January-March 1988, 15 May 1988, pp. 188–98.

Treuhaft, R. N., and S. T. Lowe. “A Nanoradian Differential VLBI Tracking Demonstration

TDA Progress Report PR 42-109, January-March 1992, 15 May 1992, pp. 40–55.

16. Global Positioning System.

Lanyi, G. “Total Ionospheric Electron Content Calibration Using Series GPS Satelli

Data,” TDA Progress Report PR 42-85, January-March 1986, 15 May 1986, p. 112

Lichten, S. M. “Precise Estimation of Tropospheric Path Delay GPS Techniques,” TD

Progress Report PR 42-100, October-December 1989, 15 February 1990, pp. 1–12.

652

Uplink-Downlink: A History of the Deep Space Networ
Freedman, A. P. “Combining GPS and VLBI Earth-Rotation Data for Improved Univers

Time,” TDA Progress Report PR 42-105, January-March 1991, 15 May 1991, pp. 1-1

Guinn, J., J. Jee, P. Wolff, F. Lagattuta, T. Drain, and V. Sierra. “TOPEX/POSEIDO

Operational Orbit Determination Results Using Global Positioning Satellites,” TD

Progress Report PR 42-116, October-December 1993, 15 February 1994, pp. 163–7

17. The Goldstone Solar System Radar.

Carpenter, R. L., and R. M. Goldstein. “Preliminary Results of the 1962 Radar Astronom

Study of Venus,” JPL-SPS 37-20, Vol. IV, 30 April 1963, pp. 182–84.

Goldstein, R. M. “Radar Observations of Icarus,” JPL-SPS 37-53, Vol. II, 30 Septemb

1968, pp. 45–48.

Leu, R. L. “X-band Radar System,” JPL Technical Report TR 32-1526, Vol. XIX: Novemb

and December 1973, 15 February 1974, pp. 77–81.

Downs, G. S., R. R. Green, and P. E. Reichley. “A Radar Study of the Backup Martia

Landing Sites,” DSN Progress Report PR 42-36, September and October 1976, 1

December 1976, pp. 49–52.

Bhanji, A. M., M. Caplan (Varian Associates, Inc.), R. W. Hartop, D. J. Hoppe, W. A

Imbriale, D. Stone (Varian Associates, Inc.), and E. W. Stone. “High Power Ka-ban

Transmitter for Planetary Radar and Spacecraft Uplink,” TDA Progress Report PR 4

78, April-June 1984, 15 August 1984, pp. 24–48.

Bhanji, A. M., D. J. Hoppe, B. L. Conroy, and A. J. Freiley. “Conceptual Design of 

1-MW CW X-band Transmitter for Planetary Radar,” TDA Progress Report PR 42-9

July-September 1988, 15 November 1988, pp. 97–111.

Renzetti, N. A., T. W. Thompson, and M. A. Slade. “Relative Planetary Rad

Sensitivities: Arecibo and Goldstone,” TDA Progress Report PR 42-94, April-June 198

15 August 1988, pp. 287–93. 

18. Telecommunications performance.

Yuen, J. H., ed. Deep Space Telecommunications Engineering. New York: Plenum Pres

1983.

65

Appendix
Layland, J. W., and L. L. Rauch. “Case Studies of Technology in the DSN: Galile

Voyager, Mariner,” published in “Evolution of Technology in the Deep Space Network

TDA Progress Report PR 42-130, April-June 1997, August 1997.

Posner, E. C., et al. “Voyager Neptune Telemetry.” Session V of ITC.USA/87, pape

87-0819 through 87-0824 of the International Telemetering Conference, Vol. XIII, cospo

sored by the International Foundation for Telemetry and Instrumentation Society 

America, 26–29 October 1987.

Posner, E. C., L. L. Rauch, and B. D. Madsen. “Voyager Mission Telecommunicatio

Firsts,” IEEE Communications Magazine 28, no. 8 (September 1990): 22–27.

19. Cost-reduction initiatives.

Jet Propulsion Laboratory, Charles T. Stelzried, ed. TMOD Technology and Science Progra

News 2, 4, 7, 8, 9 (March 1995-April 1998). http://deepspace.jpl.nasa.gov/technology.

20. Ka-band development.

Jet Propulsion Laboratory, Charles T. Stelzried, ed. TMOD Technology and Science Progra

News 1, 2, 3, 6, 7 (December 1994-February 1997). http://deepspace.jpl.nasa.gov/technology

Morabito, D., R. C. Clauss, and M. Speranza. “Ka-band Atmospheric Noise-Temperatu

Measurements at Goldstone, California, Using a 34-m Beam-Waveguide Antenna,” TM

Progress Report PR 42-132, February 1998.

Feria, Y., M. Belongie, T. McPheeters, and H. Tan. “Solar Scintillation Effects o

Telecommunication Links at Ka-band and X-band,” TMO Progress Report PR 42-12

May 1997.

Morabito, D. D. “The Efficiency Characterization of the DSS 13, 34-meter Bea

Waveguide Antenna at Ka-band (32.0 GHz and 33.7 GHz) and at X-band (8.4 GHz)

TMO Progress Report PR 42-125, May 1996.

Vilnrotter, V. A., and B. Iijima. “Analysis of Array Feed Combining Performance Usin

Recorded Data,” 42-125, May 1996.

Mysoor, N. R., et al. “Performance of a Ka-band Transponder Breadboard for Dee

Space Applications,” TMO Progress Report PR 42-122, August 1995.

654

Uplink-Downlink: A History of the Deep Space Networ
21. Other technologies.

Jet Propulsion Laboratory, Charles T. Stelzried, ed. TMOD Technology and Science Progra

News 2, 3, 4, 5, 8, 9 (March 1995-April 1998). http://deepspace.jpl.nasa.gov/technology.

22. Optical communications development. 

Hemmati, H., et al. “Comparative Study of Optical and Radio Frequency Communicatio

Systems for Deep Space Missions,” TMO Progress Report PR 42-128, February 199

Lesh, J. R., L. J. Deutsch, and C. D. Edwards. “Optical Communications for Extrem

Deep Space Missions,” Review of Laser Engineering 24, issue 12 (December 1996).

Lesh, J. R. “Impact of Laser Communications on Future NASA Missions and Groun

Tracking Systems.” CRL International Symposium on Advanced Optical Communication

and Sensing, Tokyo, Japan, 15–16 March 1995.

Wilson, K. E., J. R. Lesh, et al. “GOPEX: A Deep Space Optical Communication

Demonstration with the Galileo Spacecraft,” TDA Progress Report PR 42-103, Jul

September 1990, 15 November 1990, pp. 262–73.

Toyoshima, M., K. Araki, et al. “Reduction of ETS VI Laser Communicatio

Equipment Optical-Downlink Telemetry Collected during GOLD,” TDA Progre

Report PR 42-128, 15 February 1997.

23. DSN science.

Jet Propulsion Laboratory, Charles T. Stelzried, ed. TMOD Technology and Science Progra

News 1–9 (December 1994-April 1998). http://deepspace.jpl.nasa.gov/technology.

65

Appendix
ABOUT THE AUTHOR

Douglas J. Mudgway came to the United States in 1962 to work at NASA’s Jet Propulsio

Laboratory in Pasadena, California, following a fifteen-year career in the field of guide

missile research in Australia. At JPL, he was involved in the development and operatio

of the Deep Space Network from its infancy in the early 1960s to its maturity in th

early 1990s. He was the recipient of the NASA Exceptional Service Medal (1977) for h

contribution to the Viking mission to Mars, and the Exceptional Achievement Med

(1991) for his contribution to the Galileo mission to Jupiter. A mathematics and scien

major from the University of New Zealand (1945), Mr. Mudgway retired in 1991 an

lives in the wine country of Northern California. 

67
INDEX

A

Active Magnetospheric Particle Explorer, AMPTE, 170

Activity Plan Process, 618, 619

Advanced DSN Monitor and Control, ADMC, 616

Advanced Multimission Operations System, AMMOS, 328, 610, 620

Advanced Receiver, ARX, 473, 474

Advanced Research Projects Agency, ARPA, 7, 8, 10, 12, 18, 19, 25

Air Force, U.S., 4, 7

Allen, Lew, 602

Ames Research Center, NASA ARC, 33, 49, 51, 475

Amorose, Raymond J., 603, 612, 615

Anderson, John D., 514

Antennas

9-meter, 56, 169, 334, 336, 459, 541, 616

26-meter, 4, 10, 20, 21, 30, 37, 40, 43, 44, 50, 51, 56, 57, 58, 65, 66, 77, 84, 89, 97, 98, 100, 15

156, 157, 159, 166, 169, 265, 305, 307, 324, 328, 334, 335, 336, 383, 459, 495, 521, 597, 600, 6

34-meter, xlvi, 84, 157, 158, 159, 166, 263, 265, 285, 290, 302, 304, 307, 324, 326, 328, 331, 33

342, 344, 381, 439, 459, 462, 465, 467

64-meter, 41, 43, 46, 50, 51, 57, 58, 69, 70, 75, 77, 84, 89, 96, 98, 156, 172, 256, 263, 265, 278, 29

299, 300, 304, 337, 341, 343, 344, 481, 490, 513, 521, 597, 600

70-meter, xlvii, 285, 290, 302, 303, 304, 306, 307, 313, 329, 333, 337, 338, 339, 340, 341, 342, 34

459, 462, 463, 467, 523, 525

Apollo, 4, 35, 36, 43, 52, 54, 56, 57, 58, 73, 74, 597

Az-El, antenna, xvi, xx, xxiv, xxv, xxxiii, xxxiv, xxxv, xxxviii, xxxv, 17

Army, U.S., 4, 5, 7, 20

Asmar, Sami W., 507, 513

Astronomical Radio Interferometric Earth Surveying, ARIES, 541, 542

Astronomical Unit, AU, xxix, xxx, xxxii, 15, 16, 87, 88, 289, 306, 325, 330, 332, 333, 491, 550, 551

Atlantis, 286

Atlas-Agena, 38

Automated Real-time Spacecraft Navigation, ARTSN, 495

Australian Department of Supply (DOS)/Weapons Research Establishment (WRE), 19, 20, 22, 64

Australian Government’s Commonwealth Scientific and Industrial Research Organisation, CSIRO, 343, 52

B

Baker-Nunn, Smithsonian tracking camera, 20, 23

Baseband Assembly, BBA, 256, 385

Bayley, William H., 3, 583, 598

Bayley/Lyman Years, 601

Beggs, James, 276

Bell Telephone Laboratories, BTL, 12, 13, 15

Bendix Field Engineering Corporation, 21

Berman, Allen L., 507, 514

Big Viterbi Decoder, BVD, 303, 309, 386, 387

Bilbo, Thomas S., 594

65
Blaw-Knox Company, 9, 18, 19, 20

Block V Receiver, BVR, 314, 315, 316, 358, 474

Buffered Telemetry Demodulator, BTD, 368

Butcher, Lou, 3

Butrica, Andrew J., 173, 551

C

C-band, 281

California Institute of Technology, CIT, Caltech, 6, 8, 11, 25, 171, 487, 488, 523

California, University of, Berkeley, 341

California, University, Los Angeles, 583

Canberra, Australia, CDSCC, xxxiv, xlvi, 18, 19, 21, 30, 39, 56, 66, 75, 77, 84, 102, 173, 290, 291, 30

307, 313, 317, 324, 325, 328, 333, 337, 343, 368, 371, 379, 383, 437, 438, 459, 460, 482, 524, 52

605 

Cape Canaveral, Florida, Cape Kennedy, xxxv, 4, 5, 18, 23, 36, 37, 88, 96, 305, 328, 582

Carnegie Institute, 9

Carter, Jimmy, U.S. President, 173

Casani, John, 295, 302, 303

Cassegrain focus antenna, xxxviii

Cassini, 274, 299, 398, 408, 409, 428, 429, 430, 437, 439, 453, 497, 512

Cebreros, 158

Celestial Mechanics, 511

Central Communications Terminal, 86

Centre National d’Etudes Spatiales, CNES, 280, 327, 329, 336

Challenger, 265, 283, 295, 301, 322

Clinton, William Jefferson, U.S. President, Administration, 610

Collins Radio Company, 20, 77

Comet Giacobini-Zinner, 276, 331

Comet Halley, encounter, 274, 275, 276, 277, 278

Command and Data Console, CDC, 53

Command modulator assembly, CMA, 258, 263, 388

Command processor assembly, CPA, 258, 388

Command switching assembly, CSA, 388

Commonwealth Scientific and Industrial Research Organisation, CSIRO, 526

Compatibility Test Area 21, CTA21, 96, 97

Congress, U.S., 171

Consolidated Space and Test Center, CSTC, Air Force, 305

Corliss, William R., 42, 43, 43, 44, 45, 56, 73

Cross Support Agreements, 526

Crustal Dynamics, 541, 542, 548, 549

D

Data Capture Process, 616, 619

Data Compression, 478

Data Systems Operations Team, DSOT, 618

Declination, xxxiii

Deep Space Communications Complex, DSCC, 77, 256, 258, 264, 313, 315, 386, 389, 391, 422, 52

604, 616

658

Uplink-Downlink: A History of the Deep Space Networ
Deep Space Instrumentation Facility, DSIF, 11, 15, 16, 21, 30, 31, 32, 33, 34, 36, 37, 38, 39, 40, 50, 6

71, 507, 511, 521, 582, 591, 596, 599, 603

Deep Space Network, DSN, xxviii, xxx, xxxii, xxxiii, xxxiv, xxxv, 3, 4, 5, 6, 8, 16, 17, 18, 25, 30, 33, 3

36, 37, 38, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 54, 56, 57, 58, 61, 62, 63, 64, 65, 66, 69, 7

71, 72, 73, 74, 75, 77, 78, 82, 83, 84, 87, 89, 90, 91, 92, 93, 96, 97, 99, 100, 101, 159, 166, 16

168, 169, 170, 172, 173, 174, 176, 258, 263, 264, 265, 274, 275, 276, 277, 278, 279, 280, 281, 28

286, 288, 289, 290, 291, 292, 293, 294, 295, 296, 297, 299, 301, 302, 303, 304, 305, 306, 307, 30

310, 311, 312, 313, 315, 316, 317, 318, 319, 323, 324, 325, 326, 328, 329, 330, 331, 332, 333, 33

338, 341, 343, 368, 371, 383, 398, 434, 437, 445, 450, 458, 467, 471, 472, 478, 483, 487, 488, 48

493, 494, 498, 499, 502, 507, 508, 511, 515, 517, 521, 522, 526, 528, 550, 567, 591, 594, 597, 59

600, 602, 603, 604, 606, 615, 620

Deep Space Network Monitor and Control, DMC, 447

Deep Space Station, DSS, 3

DSS 16, 336

DSS 11, Madrid, 3, 4, 56, 84

DSS 12, 47, 84, 89, 155, 157, 158, 278, 305

DSS 13, 47, 328, 375, 458, 494, 497, 534, 542

DSS 14, 45, 47, 57, 58, 77, 84, 89, 96, 98, 306, 314, 315, 317, 330, 337, 340, 341, 342, 513, 51

542

DSS 15, 309, 314

DSS 23, 449

DSS 27, 336

DSS 34, 379

DSS 42, 56, 84, 89, 90, 158, 278 

DSS 43, 77, 84, 98, 102, 238, 314, 315, 317, 337, 338, 340, 341, 342

DSS 44, 84, 89, 90, 158

DSS 46, 336

DSS 61, 56, 84, 158, 278

DSS 62, 84, 89, 158

DSS 63, 77, 84, 98, 238, 306, 317, 338, 339, 340, 341

DSS 65, 288

Deep Space Tracking System, DSTS, ESA, 279

Defense, U.S. Department of, 4, 7, 8, 11, 18, 19

Deimos, 46

Delta Differential One-way Ranging, DDOR, 307, 512

Deutsch, Leslie J., 612

Differenced Range versus Integrated Doppler, DRVID, 71, 96, 

Digital Equipment Corporation, DEC, 264

Digitally Controller Oscillator, DCO, 263

Doppler, xxxviii, xliv, xlvi, xlvii, 5, 9, 42, 62, 70, 74, 96, 101, 174, 278, 281, 284, 287, 304, 306, 329, 33

338, 422, 472, 484, 485, 486, 507, 508, 511, 514, 518

DSCC Galileo Telemetry, DGT, 312, 313, 314, 315, 316, 317, 318, 359

Dryden, Hugh, 21

Dubridge, Lee A., 6

Dumas, Larry N., 526, 606

Dumas/Haynes Years, 606

65

Index
E

Earth Crossing Asteroid, ECA, 499

Earth Orbiter, EO, 169

Echo, balloon experiment, 13, 14, 15, 16, 17, 42, 44, 66

Edwards, Chad, 525

Effron, Leonard, 276

Eisenhower, Dwight David, U.S. President, 7, 10, 15

Ellis, Jordan, 276

Eros, asteroid, 274, 275

European Space Agency, ESA, 168, 276, 277, 278, 279, 319, 321, 325

European Space Operation Center, ESOC, 278, 279

Explorer, missions, 5

Extra-Galactic Radio Sources, EGRS, xlvi, 525

F

Faraday Rotation, FR, 513

Federal Aviation Administration, FAA, 498

Federal Republic of Germany, 170

Feedback Concatenated Decoder, FCD, 368

Felberg, Fred, 594

Finerman, Allan, 598

Flight Operations Control Center, FOCC, 34

Flight Project Mission Operations Teams, PROJ, 447

Force, Charles T., 608

Ford, Gerald, U.S. President, 102

France, French, 169

Frequency and Timing System, FTS, 447

Full Spectrum Recorders, FSR, 368

G

Galileo, 159, 166, 168, 265, 274, 275, 283, 286, 288, 294, 295, 296, 297, 298, 299, 300, 301, 302, 30

303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 322, 323, 32

331, 337, 338, 339, 340, 342, 368, 398, 408, 410, 450, 477, 478, 498, 511, 512, 608

Gates, Clarence R., 582

German Space Operations Center, GSOC, 89, 90, 305

Giberson, Walker E., 582

Giotto, 276, 277, 278, 279

Global Positioning System, GPS, 483, 486, 489, 494, 547

Goddard Space Flight Center, GSFC, 33, 56, 62, 278, 335, 591

Goldin, Daniel S., NASA Administrator, 610

Goldstein, Richard M., 16, 504, 513, 528

Goldstone, California, GDSCC, xxxii, xxxiv, xl, xlvi, 2, 10, 15, 18, 35, 37, 39, 41, 42, 43, 44, 45, 47, 5

57, 66, 69, 70, 71, 75, 77, 84, 90, 101, 157, 173, 290, 291, 302, 303, 306, 307, 316, 325, 328, 33

336, 337, 338, 341, 342, 381, 437, 438, 450, 458, 481, 482, 490, 513, 521, 523, 530, 534, 541, 54

603, 605

Goldstone Solar System Radar, GSSR, 16, 489, 491, 499, 522, 563, 566, 567

Grand Tour, 171, 173

660

Uplink-Downlink: A History of the Deep Space Networ
Greenwich Mean Time, GMT, xxxv, 102

Gravitational Wave Experiment, GWE, 323, 518

Ground Communications Facility, GCF, 39, 75, 84, 86, 368, 394, 396, 447, 597, 600, 602, 604, 614, 6

Ground Operational Equipment, GOE, 50

Ground Reconstruction Equipment, GRE, 55

Gulkis, Samuel, 524, 528

H

Helios, 86, 87, 88, 89, 90, 91, 159, 513, 514

Hall, R. Cargill, 6, 36, 73

Halley, Edmond, ii

Halley Intercept Mission, HIM, 276

Hammer, Michael, 612

Haynes, Norman R., 606, 612

Heacock, Raymond L., 171

Heftman, Kurt, 598

Higa, Walter, 551

High-Earth orbiting, HEO, 169, 256, 275, 334

High-Efficiency antenna, HEF, 299, 304

High-electron mobility transistor, HEMT, 470, 471

High-Gain antenna, HGA, 172, 284, 285, 296, 297, 307, 308, 309, 310, 311, 312, 313, 322, 323, 32

328, 332

High-Rate Telemetry System, HRT, 44, 45

High-Resolution Microwave Survey, HRMS, 537, 538, 539

Host Country Programs, 525

Hour-Angle Declination, HA-Dec, xxxiii, xxxiv, 14

Hubble Space Telescope, HST, 288, 335, 336

Hume, Alan, Australian Minister of Supply, 21

I

Inertial Upper Stage, IUS, 168, 295, 305, 324

Ingenieria y Servicios Aerospaciales, INSA, 606

Institute for Space and Astronautical Science, ISAS, 290, 445

Instituto Geografico National, Spain, 526

Instituto Nacional Tecnica Aeroespacial, INTA, Spain, 526, 605

Interface Control Documents, ICDs, 336

Interior, U.S. Department of, 4

Intercontinental Ballistic Missile, ICBM, 4

Intermediate Range Ballistic Missile, IRBM, 7

International Astronomical Union, IAU, 566

International Cometary Explorer, ICE, 169, 170, 275, 276, 277, 300, 331

International Geophysical Year, IGY, 4, 5, 7, 13, 20

International Solar Polar Mission, ISPM, 319, 320, 321

International Solar Terrestrial Physics, ISTP, 383, 408, 434

Iowa, University of, 5

66

Index
J

Jaffe, Richard, 5, 8

Jauncey, David L., 524, 528

Jet Propulsion Laboratory, JPL, xlvii, xlviii, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 2

21, 23, 25, 30, 31, 33, 35, 36, 37, 38, 39, 41, 44, 45, 46, 47, 48, 49, 50, 52, 56, 60, 61, 63, 64, 6

66, 69, 70, 72, 75, 77, 78, 83, 86, 89, 91, 93, 96, 98, 102, 171, 172, 173, 264, 276, 278, 279, 28

295, 300, 303, 305, 306, 316, 317, 323, 329, 335, 338, 339, 368, 385, 393, 414, 450, 458, 475, 48

502, 504, 522, 533, 582, 591, 594, 596, 597, 598, 601, 603, 605, 606, 610, 612, 618

Johannesburg, South Africa, DSIF 41, 20, 24, 25, 30, 37, 38, 39, 44, 62 

Hartebeestpoort dam site, 23 

Johnson, Lyndon B., U.S. President, 35

Johnson, Lyndon B., Space Center, NASA JSC, 299, 305

Johnson, Marshall S., 594

Jupiter, 173 

Amalthea, 173

Io, 173, 175

Europa, 173, 175, 299

Ganymede, 173, 175, 299

Callisto, 173, 175, 299

Jupiter Orbit Injection, JOI, 299, 315, 316

Jupiter Orbiter Probe, JOP, 294, 295

K

Ka-band, xxxviii, 440, 496, 497, 498, 512

Ka-band Link Experiment, KABLE, 328, 496, 497, 498

Kennedy Space Center, NASA KSC, Cape Kennedy, xxvii, 265, 295, 305

Klein, M. J., 504, 528

Koscielski, Charles, 3

Kuiper, Thomas B., 504, 528, 529

L

L-band, 61, 62, 281, 316 

Laeser, Richard P., 172

Laika, 4

Lairmore, Glen E., 598

Langley Aeronautical Laboratory, 13

Langley Research Center, NASA LaRC, 33, 54, 83, 87, 92

Layland, James W., 303 

Leslie, Robert A., 64, 65, 66

Levy, Gerry, 525, 533

Lewis Research Center, NASA LeRC, 299

Lincoln Laboratory, 15

linear ion trap, LIT, 485, 486

Linfield, Roger, 525

Links

One-way, 483

Two-way, 483

662

Uplink-Downlink: A History of the Deep Space Networ
Downlink, xxxix, xli, xlvi, xlviii, 23, 468, 477, 493, 551

Uplink, xxxix, xli, xlvi, 467, 468, 497, 514, 515, 517, 551

Linnes, Karl W., 73

Lockheed Martin Astronautics, 414

Low-Earth orbiter, LEO, 334, 495, 616

Low-Gain Antenna, LGA, 297, 312, 313, 323, 330

Lunik, 34

Lyman, Peter T., 502, 561, 601

M

Madrid, Spain, MDSCC, xxxiv, 18, 19, 23, 56, 75, 77, 90, 288, 291, 302, 303, 307, 325, 337, 338, 36

437, 439

Magellan, 159, 274, 283, 285, 286, 288, 299, 322, 323, 488, 513

Mallis, Richard K., 3, 20, 21, 594

Manchester, University of, 15

Mariner, xli, 16, 17, 25, 32, 33, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 50, 51, 55, 61, 62, 6

66, 70, 71, 73, 75, 78, 82, 89, 93, 96, 172, 279, 475, 490, 491, 511, 512, 514, 515, 596

Mariner Jupiter-Saturn, 171, 172

Mark, 1A, III-77, IV-A, 71, 155, 159, 166, 167, 256, 258, 264, 285, 299, 303, 304, 323, 334, 383, 38

Mars Global Surveyor, MGS, 274, 408, 413, 414, 418, 420, 439, 453, 495, 497, 511

Mars Observer, 326, 327, 328, 329, 414

Mars Orbit Insertion, MOI, 329

Mars Pathfinder, MPF, 274, 408, 421, 422, 423, 424, 425, 439, 453

Martin, James S., Jr., 92

Martin, Warren L., 70, 169

Massachusetts Institute of Technology, MIT, 15

Mathison, Richard P., 342, 343

McElroy, Neil H., 5

McKee, Dick, 24

McKinley, Edward L., 612

Melbourne, University of, 65

Merrick, William, xx, 8, 9, 69, 70

Merritt Island, Florida, 90, 96

Messerschmicht-Bolkow-Blohm, MBB, 316

Metric Data Assembly, MDA, 263

Meyer, Don, 24

Milikan, Robert A., 6

Mission Control and Computing Center, MCCC, 84, 86, 305, 601, 606, 608

Mobile Tracking Station, MTS, 37

Moffet, Allen T., 522, 528

Moon, xxxv, 6, 7, 9, 23, 31, 33, 34, 35, 52, 54, 55, 56, 57, 78

Mu, 70, 71, 90

Mudgway, Douglas J., xvi, 73, 599

Muhleman, Duane O., 514, 563

Multimission Operations Systems Office, MOSO, 328, 610, 614

Murray, Bruce, 276, 602

Mutch, Thomas A., 176

66

Index
N

NASCOM, NASA ground communications system, 52, 62, 77, 87, 90, 278, 305

National Academy of Sciences, NAS, 171

National Aeronautics and Space Administration, NASA, xxvii, xliv, xlvi, xlviii, 2, 3, 8, 11, 15, 17, 18, 1

20, 22, 23, 25, 33, 35, 36, 38, 39, 41, 42, 43, 46, 49, 50, 54, 56, 63, 64, 65, 66, 72, 77, 78, 89, 9

102, 155, 159, 168, 169, 171, 265, 275, 276, 277, 283, 286, 301, 303, 310, 319, 320, 321, 327, 32

329, 334, 335, 336, 343, 502, 521, 525, 594, 602, 605

National Bureau of Standards, NBS, 71

National Geographic, 293

National Radio Astronomy Observatory, NRAO, 290, 303, 342, 343, 435, 481, 482, 523, 526, 533

National Space Development Agency, NASDA, Japan, 277, 336

Naugle, John, 598

Naval Research Laboratory, NRL, 9

Navy, U.S., 4, 20

Near Earth Asteroid Rendezvous, NEAR, 274, 412

Neher, Victor, 6

Neptune, planet, xxix, xxxi, xxxii, 289, 290, 291, 292, 293, 294, 300, 303, 332, 333, 343, 349

Network Operations Control Center, NOCC, 86, 256, 263, 264, 323, 388, 393, 434, 447, 450, 600, 60

614, 615

New Zealand, Wellington, 6

Nigeria, South Africa, 5, 18, 19, 23

NOCC Monitor and Control, NMC, 447

NOCC Support System, NSS, 263, 264, 447

NOCC Navigation, NAV, 447

O

Occultation Data Assembly, 510

Office of Space Sciences, NASA HQ, 533

Office of Tracking and Data Acquisition, OTDA, 521, 597, 598

Olsen, Howard, 24

O’Neill, William J., 311

Optical Navigation, OPNAV, 309, 310

Orbiting Very Long Baseline Interferometry, OVLBI, 445, 446, 447, 525

Ostro, Steven J., 504, 561, 562, 564, 566

P

Parkes Radio Astronomy Observatory, 256, 290, 291, 292, 313, 343, 346, 410, 481, 482, 521

Parkes-CDSCC Telemetry Array, PCTA, 343, 344, 526

Parks, Robert J., 582

Payload Assist Module, PAM, 324

Phase-lock tracking, 472

Phobos, 46, 279, 280, 281, 282, 288

Pickering, William H., xvii, 5, 6, 35, 61, 591, 599

Piloted Space Flight Network, MSFN, 56, 57 

Pioneer, 2, 3, 4, 7, 8, 10, 11, 12, 14, 20, 43, 44, 48, 50, 51, 52, 53, 62, 66, 73, 78, 82, 84, 86, 89, 9

155, 159, 166, 167, 168, 171, 275, 276, 277, 283, 293, 294, 300, 330, 331, 341, 408, 410, 412, 47

475, 511, 513, 514, 518, 582, 597

664

Uplink-Downlink: A History of the Deep Space Networ
Planetary Radar, 550

Pluto, xxix, xxxii, xxxiii

Programmed oscillator, POCA, 263

Project Operations Control Centers, POCC, 86

Project Sequence of Events, PSOE, 618, 619

Puerto Rico, 18, 23

R

Radar Astronomy, 566

Radio Astronomy, 521

Radio Frequency Interference, RFI, 534

Radio Frequency (RF) Radiation, xxxvii, xxxix

Radio Propagation and Occultation, 514

Radio Science, 507, 508, 509, 510, 513, 514

Radioisotope Thermal Generator, RTG, 51, 305, 332

Ranger, 17, 21, 23, 24, 25, 32, 33, 34, 35, 36, 38, 60, 61, 62, 64, 78, 596

Reagan, Ronald, U.S. President, 276

Rechtin, Eberhardt, 3, 5, 7, 8, 9, 30, 61, 502, 582, 584

Redstone, arsenal, 5

Relativistic Time Delay, 517

Renaissance, 567

Renzetti, Nicholas A., iii, xix, 21, 73, 155, 458, 502, 598, 601

Robledo, 84

Roentgen, satellite, 408

Rohr Corporation, 66

Round-trip light time, RTLT, 483

S

S-band, xxxvii, xlii, xliii, xlvii, 16, 39, 47, 50, 61, 62, 63, 84, 87, 97, 98, 155, 156, 157, 166, 256, 26

264, 277, 285, 286, 290, 297, 299, 301, 304, 306, 308, 312, 313, 315, 323, 324, 325, 330, 368, 38

467, 513, 518

Sakigake, 276

San Diego, California, 5

Saturn V, 57

Search for Extraterrestrial Intelligence, SETI, 488, 502, 504, 533, 535, 536

Shoemaker-Levy Comet, 313, 316

Siegmeth, Alfred J., 73

Signal Processing Centers, SPC, 383, 384, 385, 388, 390, 394, 447

Signal-to-Noise Ratio, SNR, xxxvii, xlvii, 478, 483

Significant Advances, 529

Significant Events, 569

Venus, xxx, xxxi, 6, 15, 16, 31, 37, 38, 39, 42, 43, 46, 47, 48, 61, 78, 82, 155, 159, 167, 274, 27

283, 285, 286, 305, 306, 331, 339, 490, 511, 550, 569

Mars, Red Planet, xxvii, xxix, xxxi, xxxii, xxxv, xxxvi, 6, 31, 39, 41, 43, 44, 45, 51, 57, 62, 66, 75, 7

82, 91, 92, 93, 96, 97, 101, 102, 103, 274, 280, 281, 282, 294, 327, 328, 329, 330, 475, 490, 5

Mercury, xxix, xxxi, 78, 82, 569

Jupiter, xxvii, xxix, xxxi, xxxii, 31, 46, 50, 51, 52, 74, 78, 82, 166, 167, 169, 171, 172, 173, 175, 26

294, 295, 296, 299, 300, 301, 304, 310, 312, 313, 316, 317, 333, 478, 569

66

Index
Saturn, xxvii, xxix, xxxi, 31, 52, 166, 171, 172, 173, 176, 276, 333, 571

Earth, xxix, xxxi, xxxiii, xxxv, xliii, xlvi, 4, 5, 7, 8, 12, 13, 15, 16, 33, 37, 40, 47, 54, 57, 70, 74, 86, 8

91, 92, 100, 170, 275, 277, 284, 288, 290, 296, 325, 331, 483, 511, 517

Singapore, 5

Small Deep Space Transponder, SDST, 497

Solar Corona, wind, 513

Solar Heliospheric Observatory, Soho, 434

South African Council for Scientific and Industrial Research (CSIR)/National Institute of Telecommunicatio

Research (NITR), 19, 23, 25

South African Department of the Postmaster General, 24

Soviet Union, 169, 283

Space Flight Operations Facility, SFOF, 39, 41, 42, 52, 60, 61, 62, 63, 72, 75, 84, 86, 596, 596, 597, 59

599

Space Flight Operations Center, SFOC, 610

Space Operations Management Operations, SOMO, 335, 610, 612, 614, 619

Space Very Long Baseline Interferometry, SVLBI, 445

Spaceflight Tracking and Data Network, STDN, 90, 91

Spaulding, Wallace P., 599

Search for Extraterrestrial Intelligence, SETI, 488, 502, 504, 533, 535, 536

Sputnik, 4, 6, 78

Standard Format Data Unit, SFDU, 327

Stelzried, Charles, 276, 513

Stevens, Robertson S., 8, 9, 337, 582

Stoller, Floyd W., 20

Stone, Edward C., 171, 606, 611

Sun, xxix, xxxi, xxxii, xxxiii, xxxv, xxxvi, xxxvii, 16, 3, 35, 41, 74, 78, 87, 100, 169, 280, 325, 330, 33

507, 514

Sun-Earth-Probe, SEP, 89, 90

Support Instrumentation Requirements Document, SIRD, 72, 594

SURF, satellite, 408

Surveyor, 4, 32, 35, 36, 52, 53, 55, 64, 78, 597

Synchronization and Detection, data, 472

Synthetic Aperture Radar, SAR, 284

System Noise Temperature, xliii

T

Tau, 41, 42, 71

Tausworthe, Robert C., 70

Telecommunications and Data Acquisition, TDA, 502, 503, 506, 526, 533, 541, 549, 594, 597, 598, 60

602, 603, 605, 606, 612

Telecommunications and Mission Operations Directorate, TMOD, 334, 335, 451, 452, 458, 458, 492, 61

618, 619, 620

Birth of the TMOD, 612

Reengineering TMOD, 615

Telemetry Modulation Unit, TMU, 303

Telemetry Processor Assembly, TPA, 257, 258, 385

Thatcher, John W., 73, 599

Thor-Able, 7

666

Uplink-Downlink: A History of the Deep Space Networ
Tidbinbilla, Australia, 21, 39, 44, 64, 65, 66, 84, 522, 524, 530

Titan-Centaur, xxvii, 88, 92, 93, 100, 172, 294, 295

TOMS-EP, 408

TOPEX-POSEIDON, 489

Toutatis, asteroid, 565

Tracking and Communications Extraterrestrial, TRACE, 18

Tracking and Data Acquisition, TDA, 96

Tracking and Data Relay Satellite System, TDRSS, 169, 275, 288, 310, 335, 336, 525, 530

Trajectory correction maneuvers, TCMs, 324

Transfer Orbit Stage, TOS, 328

Travelling Wave Tube, TWT, 330

Traveling wave masers, TWM, 469, 470, 471

Triton, 290, 292

Truly, Richard H., 608

Truszynski, Gerald, 589, 598

U

Ultra-stable Oscillator, USO, xli, xlviii, 515

Ulvestad, James, 525

Ulysses, 168, 169, 265, 285, 300, 316, 321, 322, 323, 324, 325, 329, 408, 410, 499, 613

United Kingdom, 170

United States, U.S., 78, 169, 170, 276, 283

Universal Time Coordinated, UTC, xxxv, 288

Uranus, xxix, xxxi, xxxii, 166, 171, 172, 265, 290, 333, 344

Usuda Observatory, Japan, 290, 291, 292

USSR, 283

USSR Space Research Institute, IKI, Russia, 279

Urech, Jose M., 514

V

Van Allen, James A., 5, 6, 12

Vanguard, 4, 5

Vega 1, 2, 274, 277, 279, 280, 281

Venus-Earth-Earth-Gravity Assist, VEEGA, 295, 299, 301

Venus Orbiting Imaging Radar, VOIR, 283

Venus Radar Experiment, VRE, 15, 16

Venus Radar Mapper, VRM, 283

Very Large Array, VLA, 290, 291, 303, 304, 348, 351, 471, 481, 482

Very Long Baseline Interferometry, VLBI, 263, 277, 281, 304, 341, 434, 434, 435, 445, 483, 486, 487, 48

525, 526, 530, 542

Very Long Baseline Interferometry Space Observatory Program, VSOP, 434, 436, 445

Victor, Walter K., 8, 9, 550, 582

Viking, xli, 46, 51, 75, 78, 82, 83, 87, 89, 91, 92, 93, 96, 97, 98, 100, 101, 159, 166, 167, 172, 265, 27

279, 294, 327, 511, 514

Viking Mission Control Center, VMCC, 600

von Braun, Wernher, 6

66

Index
Voyager, xxvii, xxxv, xli 52, 78, 83, 157, 159, 166, 167, 168, 170, 171, 172, 173, 174, 175, 263, 264, 26

275, 276, 278, 285, 286, 288, 290, 291, 292, 293, 294, 300, 315, 331, 332, 333, 343, 344, 408, 41

475, 475, 477, 478, 488, 511, 512, 536, 613

Voyager Interstellar Mission, VIM, 331, 332

W

Wackley, Joseph A., 514

Washington, DC, 18

Weilheim, 91

Westmoreland, Paul T., 606, 612

White House, 35, 173

White Sands Missile Range, New Mexico, 4, 7, 69, 335

Woomera, Australia, DSIF 41, 20, 21, 22, 23, 25, 37, 39, 42, 66, 77, 522, 550

Island Lagoon, 20, 21

World Net, 19 

X

X-band, xxxvii, xxxviii, xlii, xliii, xlvii, 47, 84, 97, 98, 99, 100, 101, 155, 156, 157, 159, 166, 172, 17

263, 264, 277, 285, 287, 288, 290, 296, 297, 299, 301, 304, 306, 307, 309, 310, 313, 323, 325, 32

328, 329, 342, 383, 439, 445, 490, 512, 513, 518

Y

Yerbury, Michael J., 524

668

Uplink-Downlink: A History of the Deep Space Networ
THE NASA HISTORY SERIES

Reference Works, NASA SP-4000:

Grimwood, James M. Project Mercury: A Chronology. NASA SP-4001, 1963.

Grimwood, James M., and C. Barton Hacker, with Peter J. Vorzimmer. Project Gemini Technology an

Operations: A Chronology. NASA SP-4002, 1969.

Link, Mae Mills. Space Medicine in Project Mercury. NASA SP-4003, 1965.

Astronautics and Aeronautics, 1963: Chronology of Science, Technology, and Policy. NASA SP-4004, 1964.

Astronautics and Aeronautics, 1964: Chronology of Science, Technology, and Policy. NASA SP-4005, 1965.

Astronautics and Aeronautics, 1965: Chronology of Science, Technology, and Policy. NASA SP-4006, 1966.

Astronautics and Aeronautics, 1966: Chronology of Science, Technology, and Policy. NASA SP-4007, 1967.

Astronautics and Aeronautics, 1967: Chronology of Science, Technology, and Policy. NASA SP-4008, 1968.

Ertel, Ivan D., and Mary Louise Morse. The Apollo Spacecraft: A Chronology, Volume I, Through November 

1962. NASA SP-4009, 1969.

Morse, Mary Louise, and Jean Kernahan Bays. The Apollo Spacecraft: A Chronology, Volume II, November 

1962-September 30, 1964. NASA SP-4009, 1973.

Brooks, Courtney G., and Ivan D. Ertel. The Apollo Spacecraft: A Chronology, Volume III, October 1, 196

January 20, 1966. NASA SP-4009, 1973.

Ertel, Ivan D., and Roland W. Newkirk, with Courtney G. Brooks. The Apollo Spacecraft: A Chronology, Volum

IV, January 21, 1966-July 13, 1974. NASA SP-4009, 1978.

Astronautics and Aeronautics, 1968: Chronology of Science, Technology, and Policy. NASA SP-4010, 1969.

Newkirk, Roland W., and Ivan D. Ertel, with Courtney G. Brooks. Skylab: A Chronology. NASA SP-401

1977.

Van Nimmen, Jane, and Leonard C. Bruno, with Robert L. Rosholt. NASA Historical Data Book, Volume 

NASA Resources, 1958-1968. NASA SP-4012, 1976, rep. ed. 1988.

Ezell, Linda Neuman. NASA Historical Data Book, Volume II: Programs and Projects, 1958-1968. NASA S

4012, 1988.

Ezell, Linda Neuman. NASA Historical Data Book, Volume III: Programs and Projects, 1969-1978. NASA S

4012, 1988.

66

The NASA History Series
Gawdiak, Ihor Y., with Helen Fedor, compilers. NASA Historical Data Book, Volume IV: NASA Resources, 196

1978. NASA SP-4012, 1994.

Rumerman, Judy A., compiler. NASA Historical Data Book, 1979-1988: Volume V, NASA Launch Systems, Spa

Transportation, Human Spaceflight, and Space Science. NASA SP-4012, 1999.

Rumerman, Judy A., compiler. NASA Historical Data Book, Volume VI: NASA Space Applications, Aeronaut

and Space Research and Technology, Tracking and Data Acquisition/Space Operations, Commercial Programs, an

Resources, 1979-1988. NASA SP-2000-4012, 2000.

Astronautics and Aeronautics, 1969: Chronology of Science, Technology, and Policy. NASA SP-4014, 1970.

Astronautics and Aeronautics, 1970: Chronology of Science, Technology, and Policy. NASA SP-4015, 1972.

Astronautics and Aeronautics, 1971: Chronology of Science, Technology, and Policy. NASA SP-4016, 1972.

Astronautics and Aeronautics, 1972: Chronology of Science, Technology, and Policy. NASA SP-4017, 1974.

Astronautics and Aeronautics, 1973: Chronology of Science, Technology, and Policy. NASA SP-4018, 1975.

Astronautics and Aeronautics, 1974: Chronology of Science, Technology, and Policy. NASA SP-4019, 1977.

Astronautics and Aeronautics, 1975: Chronology of Science, Technology, and Policy. NASA SP-4020, 1979.

Astronautics and Aeronautics, 1976: Chronology of Science, Technology, and Policy. NASA SP-4021, 1984.

Astronautics and Aeronautics, 1977: Chronology of Science, Technology, and Policy. NASA SP-4022, 1986.

Astronautics and Aeronautics, 1978: Chronology of Science, Technology, and Policy. NASA SP-4023, 1986.

Astronautics and Aeronautics, 1979-1984: Chronology of Science, Technology, and Policy. NASA SP-4024, 198

Astronautics and Aeronautics, 1985: Chronology of Science, Technology, and Policy. NASA SP-4025, 1990.

Noordung, Hermann. The Problem of Space Travel: The Rocket Motor. Edited by Ernst Stuhlinger and J. 

Hunley, with Jennifer Garland. NASA SP-4026, 1995.

Astronautics and Aeronautics, 1986-1990: A Chronology. NASA SP-4027, 1997.

Astronautics and Aeronautics, 1990-1995: A Chronology. NASA SP-2000-4028, 2000.

Management Histories, NASA SP-4100:

Rosholt, Robert L. An Administrative History of NASA, 1958-1963. NASA SP-4101, 1966.

Levine, Arnold S. Managing NASA in the Apollo Era. NASA SP-4102, 1982.

670

Uplink-Downlink: A History of the Deep Space Networ
Roland, Alex. Model Research: The National Advisory Committee for Aeronautics, 1915-1958. NASA SP-410

1985.

Fries, Sylvia D. NASA Engineers and the Age of Apollo. NASA SP-4104, 199.

Glennan, T. Keith. The Birth of NASA: The Diary of T. Keith Glennan. J. D. Hunley, editor. NASA SP-410

1993.

Seamans, Robert C., Jr. Aiming at Targets: The Autobiography of Robert C. Seamans, Jr. NASA SP-4106, 199

Project Histories, NASA SP-4200:

Swenson, Loyd S., Jr., James M. Grimwood, and Charles C. Alexander. This New Ocean: A History of Proje

Mercury. NASA SP-4201, 1966; rep. ed. 1998.

Green, Constance McLaughlin, and Milton Lomask. Vanguard: A History. NASA SP-4202, 1970; rep. e

Smithsonian Institution Press, 1971.

Hacker, Barton C., and James M. Grimwood. On Shoulders of Titans: A History of Project Gemini. NASA S

4203, 1977.

Benson, Charles D., and William Barnaby Faherty. Moonport: A History of Apollo Launch Facilities an

Operations. NASA SP-4204, 1978.

Brooks, Courtney G., James M. Grimwood, and Loyd S. Swenson, Jr. Chariots for Apollo: A History of Mann

Lunar Spacecraft. NASA SP-4205, 1979. 

Bilstein, Roger E. Stages to Saturn: A Technological History of the Apollo/Saturn Launch Vehicles. NASA SP-420

1980, rep. ed. 1997.

SP-4207 not published.

Compton, W. David, and Charles D. Benson. Living and Working in Space: A History of Skylab. NASA S

4208, 1983.

Ezell, Edward Clinton, and Linda Neuman Ezell. The Partnership: A History of the Apollo-Soyuz Test Proje

NASA SP-4209, 1978.

Hall, R. Cargill. Lunar Impact: A History of Project Ranger. NASA SP-4210, 1977.

Newell, Homer E. Beyond the Atmosphere: Early Years of Space Science. NASA SP-4211, 1980.

Ezell, Edward Clinton, and Linda Neuman Ezell. On Mars: Exploration of the Red Planet, 1958-1978. NAS

SP-4212, 1984.

Pitts, John A. The Human Factor: Biomedicine in the Manned Space Program to 1980. NASA SP-4213, 1985

67

The NASA History Series
Compton, W. David. Where No Man Has Gone Before: A History of Apollo Lunar Exploration Missions. NAS

SP-4214, 1989.

Naugle, John E. First Among Equals: The Selection of NASA Space Science Experiments. NASA SP-4215, 199

Wallace, Lane E. Airborne Trailblazer: Two Decades with NASA Langley’s Boeing 737 Flying Laboratory. NAS

SP-4216, 1994.

Butrica, Andrew J., editor. Beyond the Ionosphere: Fifty Years of Satellite Communication. NASA SP-4217, 199

Butrica, Andrew J. To See the Unseen: A History of Planetary Radar Astronomy. NASA SP-4218, 1996.

Mack, Pamela E., editor. From Engineering Science to Big Science: The NACA and NASA Collier Trophy Resear

Project Winners. NASA SP-4219, 1998.

Reed, R. Dale, with Darlene Lister. Wingless Flight: The Lifting Body Story. NASA SP-4220, 1997.

Heppenheimer, T. A. The Space Shuttle Decision: NASA’s Search for a Reusable Space Vehicle. NASA SP-422

1999.

Hunley, J. D., editor. Toward Mach 2: The Douglas D-558 Program. NASA SP-4222, 1999.

Swanson, Glen E., editor. “Before this Decade is Out . . .”: Personal Reflections on the Apollo Program NASA S

4223, 1999.

Tomayko, James E. Computers Take Flight: A History of NASA’s Pioneering Digital Fly-by-Wire Project. NAS

SP-2000-4224, 2000.

Morgan, Clay. Shuttle-Mir: The U.S. and Russia Share History’s Highest Stage. NASA SP-2001-4225, 2001.

Center Histories, NASA SP-4300:

Rosenthal, Alfred. Venture into Space: Early Years of Goddard Space Flight Center. NASA SP-4301, 1985.

Hartman, Edwin P. Adventures in Research: A History of Ames Research Center, 1940-1965. NASA SP-430

1970.

Hallion, Richard P. On the Frontier: Flight Research at Dryden, 1946-1981. NASA SP- 4303, 1984.

Muenger, Elizabeth A. Searching the Horizon: A History of Ames Research Center, 1940-1976. NASA SP-430

1985.

Hansen, James R. Engineer in Charge: A History of the Langley Aeronautical Laboratory, 1917-1958. NASA S

4305, 1987.

Dawson, Virginia P. Engines and Innovation: Lewis Laboratory and American Propulsion Technology. NASA S

4306, 1991.

672

Uplink-Downlink: A History of the Deep Space Networ
Dethloff, Henry C. “Suddenly Tomorrow Came . . .”: A History of the Johnson Space Center. NASA SP-430

1993.

Hansen, James R. Spaceflight Revolution: NASA Langley Research Center from Sputnik to Apollo. NASA SP-430

1995.

Wallace, Lane E. Flights of Discovery: 50 Years at the NASA Dryden Flight Research Center. NASA SP-430

1996.

Herring, Mack R. Way Station to Space: A History of the John C. Stennis Space Center. NASA SP-4310, 1997

Wallace, Harold D., Jr. Wallops Station and the Creation of the American Space Program. NASA SP-4311, 199

Wallace, Lane E. Dreams, Hopes, Realities: NASA’s Goddard Space Flight Center, The First Forty Years. NASA S

4312, 1999.

Dunar, Andrew J., and Stephen P. Waring. Power to Explore: A History of the Marshall Space Flight Center. NAS

SP-4313, 1999.

Bugos, Glenn E. Atmosphere of Freedom: Sixty Years at the NASA Ames Research Center Astronautics an

Aeronautics, 1986-1990: A Chronology. NASA SP-2000-4314, 2000.

General Histories, NASA SP-4400:

Corliss, William R. NASA Sounding Rockets, 1958-1968: A Historical Summary. NASA SP-4401, 1971.

Wells, Helen T., Susan H. Whiteley, and Carrie Karegeannes. Origins of NASA Names. NASA SP-4402, 197

Anderson, Frank W., Jr. Orders of Magnitude: A History of NACA and NASA, 1915-1980. NASA SP-440

1981.

Sloop, John L. Liquid Hydrogen as a Propulsion Fuel, 1945-1959. NASA SP-4404, 1978.

Roland, Alex. A Spacefaring People: Perspectives on Early Spaceflight. NASA SP-4405, 1985.

Bilstein, Roger E. Orders of Magnitude: A History of the NACA and NASA, 1915-1990. NASA SP-4406, 198

Logsdon, John M., editor, with Linda J. Lear, Jannelle Warren-Findley, Ray A. Williamson, and Dwayne 

Day. Exploring the Unknown: Selected Documents in the History of the U.S. Civil Space Program, Volume 

Organizing for Exploration. NASA SP-4407, 1995.

Logsdon, John M., editor., with Dwayne A. Day and Roger D. Launius. Exploring the Unknown: Select

Documents in the History of the U.S. Civil Space Program, Volume II, Relations with Other Organizations. NAS

SP-4407, 1996.

Logsdon, John M., editor, with Roger D. Launius, David H. Onkst, and Stephen J. Garber. Exploring t

Unknown: Selected Documents in the History of the U.S. Civil Space Program, Volume III, Using Space. NASA S

4407, 1998.

67

The NASA History Series
Logsdon, John M., general editor, with Ray A. Williamson, Roger D. Launius, Russell J. Acker, Stephen 

Garber, and Jonathan L. Friedman. Exploring the Unknown: Selected Documents in the History of the U.S. Civ

Space Program, Volume IV, Accessing Space. NASA SP-4407, 1999.

Logsdon, John M., general editor, with Amy Paige Snyder, Roger D. Launius, Stephen J. Garber, and Reg

Anne Newport. Exploring the Unknown: Selected Documents in the History of the U.S. Civil Space Progra

Volume V, Exploring the Cosmos. NASA SP-2001-4407, 2001.

Siddiqi, Asif A. Challenge to Apollo: The Soviet Union and the Space Race, 1945-1974. NASA SP-2000-440

2000.

Monographs in Aerospace History, NASA SP-4500:

Maisel, Martin D., Demo J. Giulianetti, and Daniel C. Dugan. The History of the XV-15 Tilt Rotor Resear

Aircraft: From Concept to Flight. NASA SP-2000-4517, 2000.

Jenkins, Dennis R. Hypersonics Before the Shuttle: A Concise History of the X-15 Research Airplane. NASA S

2000-4518, 2000. 

Chambers, Joseph R. Partners in Freedom: Contributions of the Langley Research Center to U.S. Military Aircra

in the 1990s. NASA SP-2000-4519, 2000.

Waltman, Gene L. Black Magic and Gremlins: Analog Flight Simulations at NASA’s Flight Research Center. NAS

SP-2000-4520, 2000.

Portree, David S. F. Humans to Mars: Fifty Years of Mission Planning, 1950-2000. NASA SP-2001-4521, 200

Thompson, Milton O., with J. D. Hunley. Flight Research: Problems Encountered and What They Should Tea

Us. NASA SP-2000-4522, 2000.

Tucker, Tom. The Eclipse Project. NASA SP-2000-4523, 2000.

674

Uplink-Downlink: A History of the Deep Space Networ