The Future of Remote Sensing From Space:

Civilian Satellite Systems and Applications

July 1993

OTA-ISC-558

NTIS order #PB93-231322

GPO stock #052-003-01333-9
Recommended Citation:

U.S. Congress, Office of Technology Assessment, The Future of Remote

Sensing From Space: Civilian Satellite Systems and Applications,

OTA-ISC-558 (Washington, DC: U.S. Government Printing Office, July

1993).
Foreword

o

ver the past decade, the United States and other countries have increasingly

turned to satellite remote sensing to gather data about the state of Earth’s

atmosphere, land, and oceans. Satellite systems provide the vantage point and

coverage necessary to study our planet as an integrated, interactive physical and

biological system. In particular, the data they provide, combined with data from surface

and aircraft-based instruments, should help scientists monitor, understand, and

ultimately predict the long term effects of global change.

This report, the first of three in a broad OTA assessment of Earth observation

systems, examines issues related to the development and operation of publicly funded

U.S. and foreign civilian remote sensing systems. It also explores the military and

intelligence use of data gathered by civilian satellites. In addition, the report examines

the outlook for privately funded and operated remote sensing systems.

Despite the established utility of remote sensing technology in a wide variety of

applications, the state of the U.S. economy and the burden of an increasing Federal

deficit will force NASA, NOAA, and DoD to seek ways to reduce the costs of remote

sensing systems. This report observes that maximizing the return on the U.S. investment

in satellite remote sensing will require the Federal Government to develop a flexible,

long-term interagency plan that would guarantee the routine collection of high-quality

measurements of the atmosphere, oceans, and land over decades. Such a plan would

assign the part each agency plays in gathering data on global change, including

scientifically critical observations from aircraft- and ground-based platforms, as well as

from space-based platforms. It would also develop appropriate mechanisms for

archiving, integrating, and distributing data form many different sources for research and

other purposes. Finally, it would assign to the private sector increasing responsibility for

collecting and archiving remotely sensed data.

In undertaking this effort, OTA sought the contributions of a wide spectrum of

knowledgeable individuals and organizations. Some provided information; others

reviewed drafts. OTA gratefully acknowledges their contributions of time and

intellectual effort. OTA also appreciates the help and cooperation of officials with

NASA, NOAA, DOE, and DoD. As with all OTA reports, the content of this report is

the sole responsibility of the Office of Technology Assessment and does not necessarily

represent the views of our advisors or reviewers.

Roger C. Herdman, Director

iii
Advisory Panel

Rodney Nichols

Chair

Chief Executive Officer

New York Academy of Sciences

James G. Anderson

Professor

Department of Chemistry and Earth

and Planetary Sciences

Harvard University

D. James Baker1

Director

Joint Oceanographic Institutions, Inc.

William Brown

President

ERIM Corp.

Ronald Brunner

Professor

Center for Public Policy Research

University of Colorado

Joanne Gabrynowicz

Associate Professor

Department of Space Studies

University of North Dakota

Alexander F.H. Goetz

Director

Center for the Study of Earth from

Space

University of Colorado

David Goodenough

Chief Research Scientist

Pacific Forestry Center

Canada

Donald Latham

Corporate Director

Loral Corp.

Cecil E. Leith

Physicist

Lawrence Livermore National

Laboratory

John H. McElroy

Dean of Engineering

The University of Texas at

Arlington

Molly Macauley

Fellow

Resources for the Future

Earl Merritt

Vice President, Research

Earthsat Corp.

I Until May 1993,

Alan Miller

Director

The Center for Global Change

University of Maryland

Raymond E. Miller

Professor

Department of Computer Science

University of Maryland

Kenneth Pedersen

Research Professor of International

Affairs

School of Foreign Service

Georgetown University

David T. Sandwell

Geological Resources Division

Scripps Institute of Oceanography

Dorm Walklet

President

TerraNOVA International

Albert Wheelon

Consultant

NOTE: OTA appreciates and is grateful for the valuable assistance and thoughtful critiques provided by the advisory panel members. The Panel

does not, however, necessarily approve, disapprove, or endorse this report. OTA assumes full responsibility for the report and the accuracy

of its contents.

iv
Peter Blair Ray A. Williamson

Assistant Director, OTA Energy, Project Director

Materials, and International

Security Division Arthur Charo

Alan Shaw Brian McCue

Preject Staff

CONTRACTORS

Paul Bowersox

Leonard David

Ronald M. Konkel

International Security and

Commerce Program Manager Stephen Wooley

ADMINISTRATIVE STAFF

Jacqueline R. Boykin

Office Administrator

Louise Staley

Administrative Secretary

Madeline Gross

Contractor
workshop Participants

THE FUTURE OF REMOTE SENSING FROM SPACE WORKSHOP, APRIL 21,1992

Ray A. Williamson

Chair

Office of Technology

Assessment

Bruce Barkstrom

ERBE Experiment Scientist

NASA—Langley Research

Center

Francis P. Bretherton

Director

Space Science and Engineering

Center

University of Wisconsin

Donald Cobb

Division Group Leader

Space Science and Technology

Los Alamos National Laboratory

Lee Demitry

Program Manager

Advanced Research Project

Agency

Jeffrey Dozier

Professor

Center for Remote Sensing and

Advanced Optics

University of California at Santa

Barbara

Diane Evans

Manager for Earth Sciences

Programs

Jet Propulsion Laboratory

James Hansen

Director

NASA-Goddard Institute for

Space Studies

John S. Langford

President

Aurora Flight Sciences Corp.

Keith Lyon

SeaStar Program Manager

Orbital Sciences Corp.

Earl Merritt

Vice President, Research

Earthsat Corp.

Ari Patrinos

Director, Environmental

Sciences Division

U.S. Department of Energy

John C. Petheram

Manager, Space Systems programs

GE Astro-Space Division

Stanley R. Schneider

Landsat Program Manager

NASA Headquarters

Carl Schueler

Manager

Advanced Development Programs

Hughes Santa Barbara Research

Center

John Vitko, Jr.

Manager Global Climate Change

Sandia National Laboratories

Matthew R. Willard

Consultant

vi
POTENTIAL MILITARY USES OF CIVILIAN SATELLITES WORKSHOP, JULY 8,1992

Ray A. Williamson

Chair

Office of Technology

Assessment

James R. Blackwell

Director

International Security Division

Meridian Corp.

Kenneth Daugherty

Chief Scientist

Defense Mapping Agency

William Kennedy

Hughes STX

Michael Krepon

President

Henry L. Stirnson Center

Donald Latham

Corporate Director

Loral Corp.

John G. Thunen

Manager, Special Projects

Hughes-Santa Barbara Research

Center

Peter Zimmerman

Senior Fellow

Center for Strategic and

International Studies

John Hudson

Systems Officer

Defense Intelligence Agency

vii
Acknowledgments

This report has benefited from the advice of many individuals. In addition to members of the Advisory Panel and

the workshop, OTA especially would like to thank the following individuals for their assistance and support. The

views expressed in this paper, however, are the sole responsibility of the Office of Technology Assessment.

Stephen W. Altes

Aurora Flight Sciences Corp.

Donald Artis

U.S. Army Topographic

Engineering Center

Arthur Boot h

National Oceanic and Atmospheric

Administration

Andrew Boye

Sandia National Laboratories

Dino Brugioni

Fredericksburg, VA

Dixon Butler

National Aeronautics and Space

Administration

Barbara Cherry

National Aeronautics and Space

Administration

Thomas Cremins

National Aeronautics and Space

Administration

William Crocker

U.S. General Accounting Office

Brian D. Dailey

Lockheed Missiles & Space Co.,

Inc.

. . . VIII

John Dutton

Pennsylvania State University

H. Frank Eden

Martin Marietta Astro Space

Richard Eiserman

U.S. General Accounting Office

Charles Elachi

Jet Propulsion Laboratory

Bernard P. Elero

Martin Marietta Astro Space

Douglas B. Gerull

WorldView Imaging Corp.

Louis Gomberg

Hughes Space and Communications

Group

Ken Hadeen

NOAA National Climatic Data

Center

Michael Hall

National Oceanic and Atmospheric

Administration

Stephen Harper

EOSAT Corp.

Fred Henderson

Geosat Committee Inc.

W. John Hussey

National Oceanic and Atmospheric

Administration

Bhupendra Jasani

King’s College

Ma]. Frank Kelly, USAF

Department of Defense

Mary Dee Kerwin

National Aeronautics and Space

Administration

Jack Koeppen

National Oceanic and Atmospheric

Administration

Russell Koffler

Fort Washington, MD

John S. Langford

Aurora Flight Sciences Corp.

Donald Light

U.S. Geological Survey

Keith Lyon

orbital Sciences Corp.

John MacDonald

MacDonald Dettwiler
Jeffrey Marquese

Institute for Defense Analyses

Thomas Meyer

Los Alamos National Laboratory

Aram Mika

Hughes Santa Barbara Research

Center

David Moore

Congressional Budget Office

Stanley Morain

Technology Application Center

University of New Mexico

Richard Mroczynski

EOSAT Corp.

Firouz Michael Naderi

Jet Propulsion Laboratory

Douglas Namian

National Oceanic and Atmospheric

Administration

Pat Nash

National Aeronautics and Space

Administration

Ted G. Nanz

SPOT Image Corp.

Clark Nelson

SPOT Image Corp.

Scott Pace

The Rand Corp.

Carl Reber

NASA Goddard Space Flight

Center

Sally Ride

California Space Institute

University of California,

San Diego

Thomas Sever

John C. Stennis Space Center

Lisa Shaffer

National Aeronautics and Space

Administration

Kathyrn Sullivan

National Oceanic and Atmospheric

Administration

Shelby Tilford

National Aeronautics and Space

Administration

Milton C. Trichel

ERIM

Paul F. Uhlir

National Academy of Sciences

Pat Viets

National Oceanic and Atmospheric

Administration

Wulf Von Kries

MST Aerospace GMbH

Allen H. Watkins

U.S. Geological Survey

Daniel Woods

National Aeronautics and Space

Administration

Makoto Yokota

ix
Plate Descriptions

PLATE 1. Eye of Hurricane Andrew Approaching the Louisiana Coast

This image of Hurricane Andrew was taken Aug. 26, 1992, just as the eye of the storm was moving ashore. The NOAA GOES-7 image shows

bands of intense rain and the spiral “arms” of the storm.

SOURCE: NOAA NESDIS. Used with permission.

PLATE 2. Late Start of the 1993 Growing Season in the United States

The vegetation index, an indicator derived using data from the Advanced Very High Resolution Radiometer (AVHRR) flown on the NOAA

polar-orbiting operational environmental satellites, was used to detect the beginning and progress of the 1993 growing season in the United

States. The accompanying image compares values of the Normalized Difference Vegetation Index (NDVI) for mid-May in 6 consecutive years,

1988-1993.

This image shows that the development of vegetation in mid-May 1993 is below the other 5 years. In the southeastern United States and

California the area with well-developed vegetation in 1993 (NDVI between 0.1 and 0.3, yellow and light green colors) is much smaller than

for any other of the 5 years. Also, very few areas show well-developed vegetation (NDVI above 0.3, dark green color) in May 1993. In the

rest of the United States the area with low NDVI values (between 0.005 and 0.1, red and brown colors) in 1993 is much larger than in the other

5 years. Interestingly, a much larger area with underdeveloped vegetation (NDVI below 0.05, gray color) is observed this year compared with

1988-1992.

Similar images from April show that late development of vegetation in 1993 has been observed since the beginning of the usual growing

season. The current vegetation state is approximately 3 to 5 weeks behind the 1988-92 average for the entire United States. The exceptions

are southern Florida, California, and Texas, where end-of-April vegetation development was normal or ahead of normal. By mid-May nearly

35 percent of the U.S. area was more than 4 weeks behind.

SOURCE: NOAA/NESDIS, Satellite Research Laboratory. Used with permission.

PLATE 3. Vegetation Index

NOAA satellites monitor the greenness in vegetation. This Vegetation Index image shows abundant (dark green) vegetation across the Amazon

of South America, while lack of vegetation (black areas) is seen across the Sahara Desert in northern Africa.

SOURCE: NOAA/NESDIS. Used with permission.

PLATE 4. Landsat Image of the Olympic Peninsula, Washington

The Earth Observation Satellite Co. (EOSAT) generated this image from data acquired on July 21, 1988, from the LandSat 5 satellite (Thematic

Mapper bands 4,5,1 (RGB)). The permanent snowcap appears lavender; dark red distinguishes old forest growth from new (light red and cyan).

Seattle’s metropolitan area appears east of Puget Sound.

SOURCE: Photograph courtesy of EOSAT. Used with permission.

PLATE 5. Sea-Surface Temperature

NOAA satellites provides a detailed view of sea surface temperatures for use by the shipping and fishing industry. The dark red indicates the

Gulf Stream while the green and blue shades indicate the cooler coastal waters.

SOURCE: NOAA/NESDIS. Used with permission.

PLATE 6. Tidal Effects in Morecambe Bay

This multitemporal image from the ERS-1 satellite’s synthetic aperture radar shows Morecambe Bay (just north of Blackpool, UK).

Highlighted in magenta are the vast expanses of sandbanks and mud flats within the Bay that are covered by the sea at high tide (Aug. 7, 1992)

and exposed at low tide (Aug. 1 and 13). The patterns within these areas reflect the various rises, dips and drainage channels that cross the sand

and mud at low tide. The tidal effect can be observed to extend several kilometers inland up the numerous river courses.

SOURCE: European Space Agency. Used with permission.
PLATE 7. Deforestation in Brazil

This false-color, ERS-1 synthetic aperture radar image shows the Teles Pires river in Brazil (Mato Grosso State) and tropical rain forests that

have been partially cut down. A regular pattern of deforestation is clearly visible, with some rectangular patches of destroyed forest extending

over areas as large as 20 square kilometers. Since tropical forests are often obscured by clouds, the radar on ERS- 1 is well-suited to imaging

areas near the equator.

SOURCE: European Space Agency. Used with permission.

PLATE 8. Changes in the Central Pacific Ocean

This series of three panels shows monthly sea level changes in the central Pacific Ocean as observed by the TOPEX/Poseidon satellite from

November 1992 to January 1993. The area shown in red is the region where sea level is more than 15 centimeters (6 inches) greater than normal.

In the series of panels, the eastward movement of an area of high sea level is clearly visible. Such movement represents the release of vast

amounts of heat energy stored in a so-called ‘‘Warm Pool’ region of the western equatorial Pacific. When it impinges on the coast of South

America, such a current may become known as an El Nino event; past El Nino events have resulted in devastation of Peruvian fisheries,

increased rainfall amounts across the southern United States and world-wide disturbances in weather patterns that have caused severe economic

losses. These images were produced from TOPEX/Poseidon altimetry data by the Ocean Monitoring and Prediction Systems Section of the

U.S. Naval Research Laboratory. TOPEX/Poseidon is a joint project of NASA and the French space agency, Centre National d’Etudes Spatiales

(CNES).

SOURCE: Public Information Office, Jet Propulsion Laboratory, California Institute of Technology, National Aeronautics and Space Administration,

Pasadena, California. Used with permission.

PLATE 9. Ozone Depletion

Data from NOAA’s Polar-Orbiting TOVS (Tiros Operational Vertical Sounder) is used to display the rapid decline in protective stratospheric

ozone over Antarctica during the past dozen years. The growing black spot represents the lowest total ozone values,

SOURCE: NOAA, NESDIS. Used with permission.

PLATE 10. Kharg Island

By tinting the 1986 image of Kharg Island, Iran one color, and the 1987 image another, and then combining the images, analysts were able

to highlight changes on the island. Objects present in the first image but not in the second appear in blue, while objects present in the second

image but not in the first, such as the circular antiaircraft battery on the small island to the North appear yellow.

SOURCE: 1993 CNES, Provided by SPOT Image Corp., Reston, VA. Reprinted with permission.

PLATES 11 and 12, Civilian Satellites and Verification

In the first image, the Vetrino missile operating base in 1988 is shown. Overlay of the site diagram from the INF treaty shows a reasonably

good fit with observed and treaty data. Nevertheless, some differences can be identified; for example, atA the road turns in a different direction,

at B some new construction has taken place by 1988, and at C, the structure is not indicated in the treaty.

The second image shows an enlarged section from an image of the Polotsk missile operating base. Overlay of the site diagram from the

INF treaty is not a good fit in this case. For example, the orientation of a building at A is different in the image from that indicated in the treaty;

the road at B cannot be seen in the image and the perimeter fence (C)is very different. Also, considerable difference exists between the structure

at D and the road leading in or out of the facitity.

SOURCE: Bhupendra Jasani, CNES/SPOT; images processed at RAE, Farnborough, UK. Reprinted with permission.

xi
contents

1 Introduction 1

What is Remote Sensing from Space? 5

Remote Sensing Applications 6

2 Remote Sensing and the U.S. Future in Space 11

The Changing Context of Satellite Remote Sensing 11

NOAA’s Environmental Earth Observations 14

Defense Meteorological Satellite Program 15

NASA’s Mission to Planet Earth 16

NASA’s Remote Sensing Budget 18

NOAA’s Remote Sensing Budget 23

The Costs and Benefits of Satellite Remote Sensing 24

Data Continuity, Long-Term Research, and

Resource Management 25

Developing and Executing a Strategic Plan for

Space-Based Remote Sensing 26

3 Weather and Climate Observations 33

NOAA’s Operational Environmental Satellite Programs 34

Defense Meteorological Satellite Program 43

Non-U.S. Environmental Satellite Systems 44

4 Surface Remote Sensing 47

The Landsat Program 48

Non-U.S. Land Remote Sensing Systems 52

Ocean Sensing and the Ice Caps 54

Major Existing or Planned Ocean and Ice

Remote Sensing Satellites 57

5 Global Change Research 63

The U.S. Global Change Research Program 63

NASA’s Mission to Planet Earth 65

Structuring a Robust, Responsive, Global Change

Research Program 72

6 Military Uses of Civilian Remotely Sensed Data 81

7 The Role of the Private Sector 85
8 International Cooperation and Competition 89

Increased International Cooperation in Earth Monitoring

and Global Change Research 89

International Cooperation and Surface Remote Sensing 91

Maintaining a U.S. Competitive Position in Remote Sensing 92

APPENDIXES

A Research and the Earth Observing System 95

B The Future of Earth Remote Sensing

Technologies 109

C Military Uses of Civilian Remote Sensing Data 145

D Non-U.S. Earth Observation Satellite Programs 167

E Glossary of Acronyms 189

INDEX 193

xiv
Introduction

s

ince the first civilian remote sensing satellite was

launched in 1960, the United States has come increasingly to rely on space-based remote sensing to serve a

wide variety of needs for data about the atmosphere,

land, and oceans (table l-l). Other nations have followed the

U.S. lead. The vantage point of space offers a broadscale view of

Earth, with repetitive coverage unaffected by political boundaries. Recent advances in sensors, telecommunications, and

computers have made possible the development and operation of

advanced satellite systems (figure 1-1) that deliver vital information about our planet to Earth-bound users.

Many Federal agencies, including the Department of Defense

(DoD), use remotely sensed data to carry out their legislatively

mandated programs to protect and assist U.S. citizens and to

reserve and manage U.S. resources. For making routine observations of weather and climate, the National Oceanic and Atmospheric Administration (NOAA) operates two environmental

satellite systems. DoD also operates a system of environmental

satellites. 1 The scientific satellites and instruments of the

National Aeronautics and Space Administration (NASA) probe

Earth’s environment for scientific research. Future NASA

scientific satellites will include NASA’s Earth Observing

System (EOS), a series of sophisticated, low-orbit satellites to

gather global environmental data and assist in assessing global

environmental change. DoD and NASA now jointly manage the

Landsat program, which provides highly useful images of the

land and coastal waters.

I

1

1 This report is not concerned with any satellite system built exclusively for national

security purposes, except for the Defense Meteorological Satellite Program. Data from

DMSP are made available to civilian users through NOAA.
2 I Remote Sensing From Space

Table l-l--Current U.S. Civilian Satellite Remote Sensing Systemsa

System Operator Mission Status

Geostationary Operational

Environmental Satellite (GOES)

Polar-orbiting Operational

Environmental Satellite (POES)

Defense Meteorological Satellite

Program (DMSP)

Landsat

Upper Atmosphere Research

Satellite (UARS)

Laser Geodynamics Satellite

(LAGEOS)

TOPEX/Poseidon

NOAA

NOAA

DoD

DoD/NASA

EOSATb

NASA

NASA/ltaly

NASA/CNES

(France)

Weather monitoring, severe storm

warning, and environmental

data relay

Weather/climate; land, ocean

observations; emergency

rescue

Weather/climate observations

Mapping, charting, geodesy;

global change, environmental

monitoring

Upper atmosphere chemistry, winds,

energy inputs

Earth’s gravity field, continental

drift

Ocean topography

1 operational; 1994 launch of

GOES-1 (GOES-Next)

2 partially operational; 2 fully

operational; launch as needed

1 partially operational; 2 fully

operational; launch as needed

Landsat 4&5 operational, 1993

launch for Landsat 6

In operation; launched in 1991

One in orbit; another launched in

1992

In operation; launched in 1992

a The United States also collects and archives Earth data from non-us. satellites.

b EOSAT, a private corporation, operates Landsats 4, 5, and 6. DoD and NASA will operate a future LandSat 7.

SOURCE: Office of Technology Assessment, 1993.

This report is the first major publication of an

assessment of Earth observation systems requested by the House Committee on Science,

Space, and Technology; the Senate Committee on

Commerce, Science, and Transportation; the House

and Senate Appropriations Subcommittees on

Veterans Affairs, Housing and Urban Development, and Independent Agencies; and the House

Permanent Select Committee on Intelligence.

This report examines the future of civilian

remote sensing satellites and systems. In particular, it provides a guide to the sensors and systems

operating today and those planned for the future.

The report also explores issues of innovation in

remote sensing technology and briefly examines

the many applications of remotely sensed data. In

addition, the report examines the use of civilian

data for military purposes, although it does not

investigate the potential civilian use of classified

remotely sensed data acquired for national security purposes.2

The United States is entering a new era, in

which it is planning to spend an increasing

proportion of its civilian space budget on the

development and use of remote sensing technologies to support environmental study. Building and operating remote sensing systems for U.S.

Government needs could cost more than $30

billion3 over the next two decades. The extent of

future public investment in space-based remote

sensing will depend in part on how well these

systems serve the public interest. Remote sensing

activities already touch many aspects of our lives.

The future of space-based remote sensing raises

questions for Congress related to:

. U.S. commitment to global change research

and monitoring, which requires long-term

funding and continuity of data acquisition;

2 A committee of scientists organized by Vice President Albert Gore in his former role as chairman of the Senate Subcommittee on Science,

Technology, and Space, is examining the potential for such data to assist in global-change research.

3 In 1992 dollars.
Chapter I—Introduction l3

GOES-W

(USA)

1 12“W

Figure l-l—Existing Earth Monitoring Satellites

Geosynchronous weather satellites

METEOR (RUSSIA)

\

that are in either geosynchronous or polar/near-polar orbits.

SOURCE: Office of Technology Assessment, 1993.

. the role of U.S. industry as partners in

supplying sensors, satellites, ground systems, and advanced data products;

. America’s competitive position in advanced

technology; and

● U.S. interest in using international cooperative mechanisms to further U.S. economic,

foreign policy, and scientific goals.

These items of public policy intersect with

questions concerning the overall structure and

focus of the U.S. space program, and the scale of

public spending on space activities. Thus, Congress will have to decide:

●

●

●

●

The total spending for space, as well as the

allocations for major programs such as Earth

science from space, space science, space

shuttle, and the space station;

The role of remote sensing in the space

program;

The role of satellite remote sensing in U.S.

global change research; and

Congress’ role in assisting U.S. industry to

maintain U.S. competitiveness in satellite

remote sensing and related industries.

Existing and planned satellite systems raise

issues of utility, cost effectiveness, and technology readiness. The United States pioneered the
4 I Remote Sensing From Space

Box l-A-Report Appendixes

Appendix A: Global Change Research From Satellites outlines the U.S. Global Change Research Program

and examines the use of space-based remote sensing for assessing the long-term effects of global change. In

particular, it examines the roles played by NASA’s Earth Observing System, NOM’s envirormental satellites, and

foreign systems.

This report examines the issues raised by the development of new remote sensing technologies in Appendix

B: The Future of Remote Sensing Technologies. In particular, the appendix summarizes the state-of-the-art in

technology development and explores the issues raised by innovation in sensor and spacecraft design. it also

summarizes the characteristics of planned instruments that were deferred during the 1991 and 1992 restructuring

of EOS.

The Gulf War provided a clear lesson in the utility of data from civilian systems for certain military uses. More

the war, no accurate, high quality maps of Kuwait and the Gulf area existed. Hence, U.S. military planners had

to depend in part on maps generated from remotely sensed images acquired from Landsat and the French SPOT

satellite for planning and executing allied maneuvers. Appendix C: Military Uses of Civilian Sensing Satellites

explores the technical and policy issues regarding the military use of data from civilian systems.

Appendix D): Infernational Remote Sensing Efforts summarizes non-U.S. satellite systems and some of the

international cooperative programs.

SOURCE: Office of Technology Assessment, 1993.

use of space-based remote sensing in the 1960s By the early 21st century, U.S. and foreign

and 1970s; today the governments of several

other countries and the European Space Agency

(ESA) also operate highly sophisticated environmental remote sensing systems for a variety of

applications (figure l-l). For the future, other

nations are planning additional remote sensing

satellites that will both complement, and compete

with, U.S. systems. These circumstances present

a formidable challenge to the United States.

Satellite remote sensing is a major source of

data for global change research as well as weather

forecasting and other applications. Data from

these systems must be integrated with a wide

variety of data gathered by sensors on aircraft,

land, and ocean-based facilities to generate useful

information. This report explores how satellite

remote sensing fits in with these other systems. It

also addresses U.S. policy toward the remote

sensing industry. Detailed discussion of many of

this report’s findings may be found in the

appendixes (box l-A).

remote sensing systems will generate prodigious

amounts of data in a variety of formats. Using

these data will require adequate storage and the

ability to manage, organize, sort, distribute, and

manipulate data at unprecedented speeds. NASA,

NOAA, and DoD are responsible for developing

and operating the data gathering systems, yet

other government agencies and many private

sector entities will also use the data for a variety

of ongoing research and applications programs. A

future report in this assessment, expected for

release in late 1993, will examine issues connected with data analysis, organization, and

distribution.

The distribution and sales of data form Landsat

and other land remote sensing systems raise

issues of public versus private goods, appropriate

price of data, and relations with foreign data

customers. These issues are discussed in a background paper, Remotely Sensed Data From Space:
Chapter I–Introduction l5

Thermal

infrared

Shortwave

Infrared

Near 10 pm

Infrared

2-3 pm A

Vlslble

0.8-1 pm \

?

b

.45- 0.8 pm

A~

~

by \, h ‘\

h ~ “\ l! \ \ ‘\ \

\ \ Cloud

Sensors View Earth

Radar microwave

SOURCE: Japan Resources Observation System Organization, JERS-I Program Description; Office of Technology Assessment, 1993.

Distribution, Pricing, and Applications, which a distance. The term was coined in the early 1960s

was released by OTA in July 1992.4

when data delivered by airborne sensors other

than photographic cameras began to find broad

WHAT IS REMOTE SENSING application in the scientific and resource manageFROM SPACE? ment communities. Remote sensing instruments

Remote sensing is the process of observing, measure electromagnetic radiation emitted or

measuring, and recording objects or events from reflected by an object (figure 1-2) and either

4U.S. Congress, Office of Technology Assessment, Remotely Sensed Data from Space: Distribution, Pricing, and Applications

(Washington, DC: Office of Technology Assessment, International Security and Commerce Program July 1992).
6 I Remote Sensing From Space

Box 1-B-How Remote Sensors “See” Earth

Earth receives, and is heated by, energy in the form of electromagnetic radiation from the sun (figure 1-3).

About 95 percent of this energy falls in wavelengths between the beginning of the x-ray region (290x 109 meters)

and long radio waves (about 250 meters).

Some incoming radiation is reflected by the atmosphere; most penetrates the atmosphere and is

subsequently reradiated by atmospheric gas molecules, clouds, and the surface of Earth itself (including, for

example, forests, mountains, oceans, ice sheets, and urbanized areas); about 70 percent of the radiation reaching

Earth’s surface is absorbed, warming the planet. Over the long term, Earth maintains a balance between the solar

energy entering the atmosphere and energy leaving it (figure 1-4). Atmospheric winds and ocean currents

redistribute the energy to produce Earth’s climate.

Clouds are extremely effective unreflecting and scattering radiation, and can reduce incoming sunlight by as

much as 80 to 90 percent. One of the important functions of future remote sensors will be to measure the effects

of clouds on Earth’s climate more precisely, particularly clouds’ effects on incoming and reflected solar radiation.

Remote sensors maybe divided into passive sensorsthat observe reflected solar radiation or active sensors

that provide their own illumination of the sensed object. Both types of sensors may provide images or simply collect

the total amount of energy in the field of view:

Passive sensors collect reflected or emitted radiation. These include:

. an imaging radiometer that senses visible, infrared, near infrared, and ultraviolet wavelengths and

generates a picture of the object;

. an atmospheric sounder that collects energy emitted by the atmosphere at infrared or microwave

wavelengths. Used to measure temperatures and humidity throughout the atmosphere.

Active sensors include:

● a radar sensor that emits pulses of microwave radiation from a radar transmitter, and collects the scattered

radiation to generate a picture;

. a scatterometer that emits microwave radiation and senses the amount of energy scattered back from the

surface over a wide field of view. It can be used to measure surface wind speeds and direction, and

determine aloud content;

● a radar altimeter that emits a narrow pulse of microwave energy toward the surface and times the return

pulse reflected from the surface;

. a lidar altimeter that emits a narrow pulse of laser light toward the surface and times the return pulse

reflected from the surface.

SOURCE: Office of Technology Assessment 1993.

transmit data immediately for analysis or store the REMOTE SENSING APPLICATIONS

data for future transmission (box l-B). Photo- Earth orbit provides unique views of Earth and

graphic cameras, video cameras, radiometers,

lasers, and radars are examples of remote sensing

devices. Sensors can be located on satellites,

piloted aircraft, unpiloted aerospace vehicles

(UAVS), or in ground stations. Thus, the data

acquired by space-based remote sensing feed into

a wide array of mapping and other sensing

services provided by surface and airborne devices.

its systems. Space-based sensors gather data from

Earth’s atmosphere, land, and oceans that can be

applied to a wide variety of Earth-bound tasks

(box l-C). Probably the best known of these

applications is the collection of satellite images of

storms and other weather patterns that appear in

the newspapers and on television weather forecasts each day. Such images, along with soundings and other data, allow forecasters to predict
Chapter I—Introduction l7

Figure l-3—incoming, Reflected, and Scattered Solar Radiation

. ....

200

0

..—.

IL Top of the atmosphere

Scattered energy

I

This figure shows the shortwave radiation spectrum for the top of the atmosphere, and as depleted by passing through the

atmosphere (in the absence of clouds). Most of the energy that is reflected, absorbed or scattered by the Earth’s atmosphere is

visible or short-wave infrared energy (from.4 micron to 4 microns). In the thermal infra-red, most attenuation is by absorption. Short

wavelength radiation is reflected by clouds, water vapor, aerosols and air; scattered by air molecules smaller than radiation

wavelengths; and absorbed by ozone in shorter wavelengths (<O.3 micron), and water vapor at the longer visible wavelengths

(>1.0 micron).

SOURCE: Andrew M. Carleton, Satellite Remote Sensing in Climatology, CRC Press, 1991, pp. 44-45.

the paths of severe storms as they develop, and to

present dramatic, graphic evidence to the public.

When large storms head toward populated areas,

such as happened after Hurricane Andrew developed in August 1992 (plate 1), consecutive

satellite images, combined with other meteorological data, coastal topography, and historical records, provide the basis on which to predict

probable trajectories and to issue advance warning about areas of danger. 5 U.S. and foreign

environmental satellites also provide valuable

data on atmospheric temperature, humidity, and

winds on a global scale.

Government agencies with the responsibility of

managing large tracts of land, or of providing

information regarding land conditions, make use

5 Thousands of people evacuated south Florida and low lying areas near New Orleans before the September 1992 Hurricane Andrew struck

land.
8 I Remote Sensing From Space

Figure 1-4-Earth’s Radiation Budget

Earth’s radiation budget is the balance between incoming solar radiation and outgoing radiation. Small changes in this balance could

have significant ramifications for Earth’s climate. Incoming solar radiation is partially reflected by the atmosphere and surface(30%).

The Earth reemits absorbed energy at longer, infrared wavelengths. Some of this energy Is trapped by natural and anthropogenic

atmospheric gases-the greenhouse effect.

SOURCE: Japan Resources Observation System Organization, Office of Technology Assessment, 1993.

of data from the Landsat or the French SPOT

series of land remote sensing satellites (table 1-2).

They also use data from the NOAA Advanced

Very High Resolution Radiometer (AVHRR) to

create vegetation maps (plate 2)0 Commercial

data users with interests in agriculture and forestry, land use and mapping, geological mapping

and exploration, and many other industrial sectors

also use data acquired from the land remote

sensing satellite systems.6

Data gathered by recently launched foreign

synthetic aperture radar instruments on European

and Japanese satellites provide information concerning ocean currents, sea state, sea ice, and

ocean pollution for both governmental and commercial applications. U.S. satellites have made

significant contributions to the science of radar

sensing and the measurement of Earth’s precise

shape.7 The U.S./French TOPEX/Poseidon satellite, launched in 1992, will provide measurements

6 The city of Chicago also used LandSat and SPOT data in the aftermath of flooding in its underground tunnels in early 1992.

7 I.e., Earth’s geoid.
—

Chapter I–Introduction l9

Box l-C-The Use of Satellite Remote Sensing

Remote sensing from space provides Scientific, industrial, civil governmental, military, and individual users

with the capacity to gather data for a variety of useful tasks:

1. simultaneously observe key elements of vast, interactive Earth systems (e.g., clouds and ocean plant

growth);

2. monitor clouds, atmospheric temperature, rainfall, wind speed, and direction;

3. monitor ocean surface temperature and ocean currents;

4. track anthropogenic and natural changes to environment and climate;

5. view remote or difficult terrain;

6. provide synoptic views of large portions of Earth’s surface, unaffected by political boundaries;

7. allow repetitive coverage over comparable viewing conditions;

8. determine Earth’s gravity and magnetic fields;

9. identify unique geologic features;

10. perform terrain analysis and measure moisture levels in soil and plants;

11. provide signals suitable for digital or optical storage and subsequent computer manipulation into

imagery; and

12. give potential for selecting combinations of spectral bands for identifying and analyzing surface

features.

In addition, data from space provide the following advantages:

1. Convenient hsitoric record, stored on optical or magnetic media and photographs: each data record,

when properly calibrated with in situ data, establishes a baseline of critical importance in recognizing the

inevitable environmental and other changes that occur.

2. Tool for inventory and assessment: satellite images can be used whenever a major natural or

technological disaster strikes and massive breakdowns of communication, transportation, public safety,

and health facilities prevent the use of normal means of inventory and assessment.

3. Predictive tool:property interpreted data used with models can be used to predict the onset of natural

and technological disasters.

4. P/arming and management ted: data can be used for a variety of planning and management

purposes.

SOURCE: Office of Technology Assessment, 1993.

of global ocean topography and ocean circulation When properly archived and made available to

(plate 8). the research community, these data can result in

All of the preceding satellite types also gener- information useful for modeling the effects of

ate data vital to understanding global change. climate and environmental change.
10 I Remote Sensing From Space

Table 1-2--Summary of Land Remote Sensing Applications

Agriculture Environmental management

Crop inventory Water quality assessment and planning

Irrigated crop inventory Environmental and pollution analysis

Noxious weeds assessment Coastal zone management

Crop yield prediction Surface mine inventory and monitoring

Grove surveys Wetlands mapping

Assessment of flood damage Lake water quality

Disease/drought monitoring Shoreline delineation

Forestry and rangeland

Oil and gas lease sales

Productivity assessment

Resouroe inventory

Dredge and fill permits

Identification of crops, timber and range

Forest habitat assessment

Marsh salinization

Wildlife range assessment Water resources

Fire potential/damage assessment Planning and management

Surface water inventory

Defense Flood control and darnage assessment

Mapping, charting, and Geodesy

Terrain analysis

Snow/ice cover monitoring

Limited reconnaissance

Irrigation demand estimates

Monitor runoff and pollution

Land cover analysis Water circulation, turbidity, and sediment

Land resource management Lake eutrophication survey

Land cover inventory Soil salinity

Comprehensive planning Ground water location

Corridor analysis

Facility siting

Geological mapping

Flood plain delineation

Lineament mapping

Lake shore management

Mapping/identification of rock types

Mineral surveys

Fish and wildlife Siting/surveying for public/private facilities

Wildlife habitat inventory Radioactive waste storage

Wetlands location, monitoring, and analysis

Vegetation classification

Land use and planning

Precipitation/snow pack monitoring

Growth trends and analysis

Land use planning

Salt exposure Cartography

Land capacity assessment

Solid waste management

SOURCE: Office of Technology Assessment, 1993.
Remote

Sensing

and the

U.S. Future

. in Space 2

C ivilian satellite remote sensing has demonstrated its

utility to a variety of users. Its future will depend on how

well the systems meet the needs of data users for:

. monitoring the global environment;

. long-term global change research and assessment;

. monitoring and managing renewable and nonrenewable

resources;

● mapping, charting, and geodesy; and

. national security purposes.

The future of satellite remote sensing will also be closely tied

to the overall direction and strategy of the U.S. civilian and

military space programs, which are changing in response to

broadening U.S. political and economic agendas. The National

Oceanic and Atmospheric Administration (NOAA), National

Aeronautics and Space Administration (NASA), Department of

Defense (DoD), and the Departments of Interior (DOI), Agriculture (DOA), and Energy (DOE), maintain substantial expertise in remote sensing. The diversity of remote sensing

applications in government and the private sector, and the

potential conflict between public and private goods greatly

complicate the task of establishing a coherent focus for

space-based remote sensing programs.

THE CHANGING CONTEXT OF SATELLITE

REMOTE SENSING

For the past several years, representatives from government,

industry, and academia have engaged in a vigorous debate over

11
12 I Remote Sensing From Space

the future of America’s civilian space program.l

This debate, spurred in part by the end of the Cold

War and other dramatic changes in the world’s

political, economic, and environmental fabric,

has reaffirmed the fundamental tenets of U.S.

civilian space policy, first articulated in the

National Aeronautics and Space Act of 1958.

Participants in this debate have generally agreed

that publicly supported U.S. space activities

should:

●

●

●

●

●

demonstrate international leadership in space

science, technology, and engineering;

contribute to economic growth;

enhance national security;

support the pursuit of knowledge; and

promote international cooperation in science.

2

Policymakers further agree that U.S. space activities should:

. include consideration of commercial content; 3 and

. support research on environmental concerns,

including the U.S. Global Change Research

Program.4

In addition, policymakers have generally supported the four major program elements of U.S.

civilian space efforts-space science, environmental observations conducted from space, maintaining a piloted space transportation program,

and developing a permanent human presence in

space. However, policymakers continue to debate, primarily through the budget and appropriations processes, how much to invest in space

activities relative to other federally funded activities, and what weight to give each element of the

U.S. space program.5 The yearly distribution of

priorities within the overall civilian space budget

will have a marked effect on how much benefit

the United States will derive from remote sensing

activities.

For most of the first three decades of the U.S.

space program, weather monitoring and military

reconnaissance have exerted the primary influences on remote sensing planning and applications. More recently, worldwide concern over the

degradation of local environments and the increasing threat of harmful global change from

anthropogenic causes have begun to influence the

direction of the U.S. space program. Scientists

disagree over the magnitude of potential global

change, its possible consequences, and how to

mitigate them. Yet they do agree that future

environmental changes could affect the global

quality of life and threaten social structure and

economic viability. Because adaptation to, and

remediation of, environmental change could be

expensive, predicting the extent and dynamics of

change is potentially very important. Scientists

face two major impediments in attempting to

understand whether harmful global change is

occurring and, if so, how to mitigate its effects:

large uncertainties in existing climate and environmental models, and large gaps in the data that

support these predictive models. Hence, the

United States has decided to increase the funding

allocated to characterizing and understanding the

processes of global environmental change.

1 See, for example: Vice President’s Space Policy Advisory Board, A Post Cold War Assessment of U.S. Space Policy (Washi.ngtom DC:

The Wbite House, December 1990); Advisory Committee on the Future of the U.S. Space Program, Report of the Advisory Com”ttee on the

Future of the U.S. Space Program @%shingtom DC: U.S. Government Printing OffIce, December 1990).

2 The National Aeronautics and Space Act of 1958 (Public Law 85-568), Sec. 102.

3

1986 amendment to the National Aeronautics and Space Act of 1958; A Post Cold War Assessment of U.S. Space Policy, op. cit.; Repon

of the Advisory Committee on the Future of the U.S. Space Program, op. cit.

4 A post cold warAsses~nt Of U.S. Space Policy; op. cit.; Report of the Advisory Cow”tree on the Future of the U.S. Space program,

op. cit.

5 Note, for example, that funding for space station Freedom has survived three major attempts within Congress to te rminate it. Opponents

of the space station have vowed to continue their efforts to terminate the space station program in the 103d Congress.
Chapter 2—Remote Sensing and the U.S. Future in Space I 13

0

Figure 2-1—1992 and 1993 U.S. Global Change Research Program Budgets, by Agency

Department of Agriculture.

SOURCE: U.S. Global Change Research Program.

Several Federal agencies are involved in gathering global change data and/or analyzing them to

provide environmental information. The U.S.

Global Change Research Program (USGCRP)

was organized to coordinate the Federal global

change research effort and give it focus and

direction. The interagency Committee on Earth

and Environmental Science (CEES) oversees the

development and implementation of USGCRP.6 

CEES was established to advise and assist the

Federal Coordinating Council for Science, Engineering Sciences, and Technology (FCCSET)

within the White House Office of Science and

Technology Policy. For fiscal year 1993, Congress appropriated $1.327 billion among Federal

agencies for global change research (figure 2-1).7

NASA’s spending on global change research

equals about 69 percent of this total. Thus, in

budget terms, NASA has become the de facto

lead agency for global change research. In large

part this follows from the fact that space systems

are inherently costly to build, launch, and operate.

Because space-based remote sensing offers a

broad scale, synoptic view and the potential to

create consecutive, consistent, well-calibrated

data sets, it provides a powerful means of

gathering data essential to understanding global

environmental change. Space-based remote sensing also contributes substantially to general

progress in the Earth sciences necessary to model

environmental processes and interpret observed

environmental changes. However, sensors based

on satellite platforms have significant limitations

of spatial resolution, flexibility, and timeliness.

For many important global change research

questions, sensors mounted on airborne platforms

and surface facilities provide data much more

effectively or efficiently (see app. B). Thus, the

space component is only one aspect of these

activities, and must be planned in conjunction

with the other components as an integrated data

collection system.

6 Through its Subcommittee on Global Change Research.

7 The President’s Budget called for devoting $1.372 billion to global change research programs. The appropriated level for fiscal year 1992

W&i $1.11 billion.
14 I Remote Sensing From Space

NOAA’S ENVIRONMENTAL

EARTH OBSERVATIONS

NOAA’s operational meteorological satellite

systems, managed by the National Environmental

Satellite, Data and Information Service

(NESDIS), consist of the Geostationary Operational Environmental Satellites (GOES—figure

2-2) and the Polar-orbiting operational Environmental Satellite (POES), also referred to as the

Television InfaredObserving Satellites (or TIROS

—see figure 2-3). GOES satellites, which orbit at

geostationary altitudes,8 provide both visiblelight and infrared images of cloud patterns, as

well as “soundings,” or indirect measurements,

of the temperature and humidity throughout the

atmosphere. NOAA has been operating GOES

satellites since 1974. Data from these spacecraft

provide input for the forecasting responsibilities

of the National Weather Service, which is also

part of NOAA. Among other applications, the

GOES data provide advance warning of emerging

severe weather, as well as storm monitoring.

The POES satellites, which circle Earth in low

polar orbits,9 provide continuous, global coverage

of the state of the atmosphere, including elements

of the weather such as atmospheric temperature,

humidity, cloud cover, and ozone concentration;

surface data such as sea ice and sea surface

temperature, and snow and ice coverage; and

Earth’s energy budget. The National Weather

Service also uses these satellite data to create its

daily weather forecasts.

Data from both satellite systems also contribute to the long-term record of weather and

climate, maintained by NOAA in its archives.10

The data that NOAA has already collected and

Figure 2-2—The Geostationary Operational

Environmental Satellite

1

S band bicone

omni antenna

S band high

VAS \ esunshal er

r

— Radial

thruster X-ray_

sensor

‘

- Earth

sensors

HEPA

archived constitute an important resource for the

study of global change. NOAA and NASA have

begun to assemble data sets from these archives

for use in global change research projects. However, the data are also limited because the satellite

instruments are not calibrated to the level required

for detecting subtle changes in global climate, or

minute environmental responses to climate

change. If future sensors aboard NOAA’s satellites were to incorporate better calibration techniques, they could make more substantial contributions to global change research. If Congress

believes it is important to improve the utility of

data gathered from the NOAA sensors for

8 Oeostationary orbit is a special case of the geosynchronous orbi~ in which satellites orbit at the same rate as any point on Earth’s equator.

A geostationary satellite appears to maintain the same position above the equator throughout a 24-hour cycle, and is therefore able to monitor

weather conditions within its field of view on a continuous basis.

s Satellites in polar orbit circle in orbits that pass over the poles. They are therefore capable of gathering data from the entire surface as the

Earth spins on its axis. The revisit period of these satellites depends on the altitude at which they orbit and the field of view of the sensing

instrument.

10 me pm NOAA WCMWS are Natiod Climatic Data Center, Asheville, NC; National Oceanographic Data Center, Washingto% DC;

and National Geophysical Data Center, Boulder, CO.
Chapter 2—Remote Sensing and the U.S. Future in Space I 15

HI

Figure 2-3-NOAA-9, One of the Polar-Orbiting Operational Satellite Series

SOURCE: Martin Marietta Astro Space.

global change research it may wish to direct

NOAA to plan for sensors with more sensitive

calibration. Because improved calibration would

require moderate additional cost, Congress

would also need to increase NOAA’s budget

for satellite procurement and operation.

The term ‘‘operational’ applied to NOAA’s

satellite systems refers primarily to the way in

which they are managed. Such systems have a

large established base of users who depend on the

regular, routine delivery of data in standard

formats. Significant changes in data format or in

the types of data delivered can mean great

expense for these users. Gaps or loss of continuity

in the delivery of data may also have a substantial

negative economic impact. Research satellite

systems, on the other hand, generally have

short-term (3 to 5 years) commitments from

agencies, and have a much smaller base of users.

Because these users may also directly contribute

to instrument design, they are more able to adjust

to major changes in data format.

DEFENSE METEOROLOGICAL

SATELLITE PROGRAM

The Air Force Space Command operates the

Defense Meteorological Satellite Program (DMSP—

figure 2-4), to support DoD’s special needs for

weather data. DMSP employs a satellite platform

very similar to the NOAA POES system, and

operates in near-polar orbit, but carries somewhat

different instruments.

Critics of the policy of maintaining g separate

polar orbiting systems argue that the United

States cannot afford both systems.11 DoD and

NOAA counter that each satellite system serves a

unique mission. The NOAA satellites routinely

provide data to thousands of U.S. and international users. DMSP serves a variety of specialized

military needs and provides valuable microwave

data to the civilian community. Previous attempts

to consolidate the two systems have resulted in

increased sharing of data and other economies.

However, because of the different requirements

11 us. conpe~~, (j~n,-~~ ~com~g Office, NS1~ 87.107, U, S. weather Satellites: AchiO,ing Economies of Scale @’&$hh@OU, ~:

U.S. Government I%nting Office, 1987).
16 I Remote Sensing From Space

for data from the two existing systems, such

efforts have not led to an integrated system.

Congress may wish to revisit the question of

the possible consolidation of DMSP and the

NOAA polar orbiting system as it searches for

ways to reduce the Federal deficit. Such a study

should look for innovative ways for NOAA and

DoD to work in partnership to carry out the base

missions of both agencies.

NASA’S MISSION TO PLANET EARTH

In conjunction with its international partners,

the United States plans a program of civilian

Earth observations to provide, by the early years

of the next century, the comprehensive collection

of data on resources, weather, and natural and

human-induced physical and chemical changes

on land, in the atmosphere, and in the oceans.

These programs are unprecedented in both their

scope and their cost.

NASA’s Earth Observing System (EOS) of

satellites is the centerpiece of NASA’s Mission to

Planet Earth. It is being designed to provide

continuous high-quality data over 15 years12 that

can be related to the scientific study of:

1.

2.

3.

4.

5.

6.

large-scale transport of water vapor;

precipitation;

ocean circulation and productivity;

sources and sinks of greenhouse gases

(gases such as carbon dioxide and methane

that contribute to greenhouse warming) and

their transformations, with emphasis on the

carbon cycle;

changes in land use, land cover, and the

hydrology and ecology of the land surface;

glacier and polar ice sheets and their relationship to sea-level;

‘7.

8.

ozone and its relationship to climate and the

biosphere; and

the role of volcanic activity in climate

change.

EOS planners expect these data to assist in

understanding and monitoring the physical, chemical, and biological processes of global change,

predicting the future behavior of Earth systems,

and assessing how to react to global change.

Measurements of these global change processes can be divided into two types:13

1.

2.

Long-term monitoring-to determine if climate is changing, to distinguish anthropogenic from naturally induced climate

change, and to determine global radiative

forcings and feedback.

‘‘Process” studies-detailed analysis of the

physics, chemistry, and biology that govern

processes ranging from the formation of the

Antarctic ozone hole to the gradual migration of tree species.

Some scientists have raised concerns over 1)

whether the EOS program as currently configured

is optimally designed to perform these different

missions, 2) whether the EOS program will

address the most pressing scientific and policyrelevant questions, and 3) whether important data

on issues such as global warning will be available

soon enough to assist policymakers. EOS program officials point to repeated and extensive

reviews by interdisciplinary panels in the selection of instruments and instrument platforms as

evidence that their program is properly focused.

The central role of the EOS program has resulted

in a USGCRP budget that is heavily weighted

toward satellite-based measurements. As a result,

some researchers express concern that:

12 To achieve 15.yw&ti sets, EOS ‘AM’ and “PM’ platforms would be flown 3 times (the 130111i.Wd lifetime Of theSephM’fOrTJ3S k 5 YWS).

Scientists expect that 15 years will be long enough to obseme the effects of climate change caused by the sunspot cycle (1 1 years), several El

Nines, and eruptions of several major volcanoes. This period would be sufilcient to observe the effects of large-scale changes such as

deforestation. Scientists are less certain whether it will be possible to distinguish the effects of greenhouse gases on Earth’s temperature from

background fhlCtlMtiOllS.

13 see ~p. B for more detaik of the distinction between theSe hVO typeS of ~~.
— .

Chapter 2—Remote Sensing and the U.S. Future in Space I 17

Figure 2-4-A Defense Meteorological Satellite DOE, DoD, and other relevant departments

These satellites are similar to the NOAA satellite shown in

figure 2-3, although the sensor suite is somewhat different.

SOURCE: Department of Defense.

1.

2.

The limitations of satellite-based platforms

will prevent process-oriented studies from

being performed at the level of detail that is

required to address the most pressing scientific questions;

Continuous long-term (decadal time-scale)

monitoring is at risk, because of the highcost, long lead times, and intermittent

operations that have historically characterized the design, launch, and operation of

multi-instrument research satellites.

According to those holding these views, a more

balanced EOS program would provide greater

support for small satellites, and a more balanced

USGCRP program might include greater support

for groundbased measurement programs, including ocean measurement systems, and alternative

sensor platforms, such as long-duration, highaltitude UAVS. Greater support for complementary non-space-based elements of the

USGCRP could be provided either by redirection of already tight NASA budgets, or from

greater support for the USGCRP from the

direct each agency to provide explicit support

for data that would complement the data

gathered by satellite. This may require a few tens

of millions of dollars of additional funding

annually between now and the end of the century.

Such additional funds would be quite small

compared to the $8 billion EOS program, but

would vastly enhance the value of the data from

the EOS satellites.

Redirecting funds from within the EOS program would be extremely difficult because the

program has already experienced two significant

reductions of scope since Congress approved it as

anew start in fiscal year 1991. At the time, NASA

had estimated it would need about $17 billion

between 1991 and 2000 to complete the first

phase of its EOS plans. Concerns over NASA’s

plans to rely on a few extremely large, expensive

satellite platforms,14 and funding uncertainties,

caused Congress in the fiscal year 1992 appropriations bill to instruct NASA to plan on receiving

only $11 billion during the first phase of EOS.15

Although this restructuring led to the cancellation

of some instruments and a deferral of others, it

generally resulted in a lower risk science program

that is more heavily focused on climate change.

When, during 1992, the magnitude of likely

future constraints on the Federal budget became

clear, Congress further reduced planned spending

for the frost phase of EOS to $8 billion. The

congressional action was consistent with an

internal NASA effort to reduce the costs of its

major programs by about 30 percent. This second

reduction of scope has led NASA to cancel

additional instruments, increase reliance on foreign partners to gather needed global change data,

cut the number of initial data products, and reduce

program reserves. Reduction of reserves for

instrument design and construction will increase

14 ~epo~ of the Ea~h ob~em[ng System (EO,$) E~g~neen’ng Review co~’ftee, ~w~d Friem~ cm= September 1991.

15 See ch. 5, Global @nge Resea.rc~ for a more detailed account of theSe COngreSSiOrIid ftCtiOm.
18 I Remote Sensing From Space

SOURCE: NASA, NOAA, DoD.

the risk that the EOS instruments will not achieve

their planned capability. Further reductions in

funding for the EOS program are likely to

constrain EOS scientists and sharply reduce

their flexibility to follow the most important

global change science objectives.

Because NASA expects to operate the EOS

satellites and its EOS Data and Information

System (EOSDIS) for at least 15 years after the

launch of the second major satellite in 2000, the

program will necessarily take on the characteristics of what has been called an “operational

program”—sustained, routine acquisition of data

that must be routinely available to researchers and

other users on a timely basis. In order to achieve

maximum effectiveness, NASA’s EOS program must be organized and operated with

great attention to the regular, timely delivery

of data.

Between now and the end of the century,

when the first EOS satellites begin to transmit

data to Earth, NASA scientists will rely on a

series of Earth Probes and other satellites, including NASA’s Upper Atmosphere Research Satellite, the U.S./French TOPEX/Poseidon, Landsat,

and the NOAA operational satellites for global

change data. The data from these systems will be

critical for early understanding of certain atmospheric and ecological effects.l6

NASA’S REMOTE SENSING BUDGET

The Federal budget for building and operating

existing and planned civilian satellite remote

sensing systems is spread across three agencies

—DoD, NASA, and NOAA-but most funds are

in NASA’s budget (table 2-1 and figure 2-5).

Examining NASA’s budget for remote sensing

activities in the context of its other program

commitments reveals that the disparity between

NASA’s plans and its expected future funding is

still growing, despite NASA’s recent efforts to

reduce its funding gap by reducing the size of

EOS, space station, and space shuttle. NASA has

projected an overall budget increase of 13 percent

between fiscal year 1993 and fiscal year 1996

(figure 2-6, table 2-2). Should anticipated funding

not materialize, NASA will have little budget

flexibility to respond to unforeseen problems in

its Mission to Planet Earth programs.17

The large yearly Federal deficit has created

pressure to save money in the discretionary

portion of the Federal budget. Civilian space

activities account for about 2.8 percent of U.S.

discretionary budget authority in fiscal year

1993.18 In appropriating NASA’s funds for fiscal

year 1992, the House and Senate stated that

NASA, which receives the lion’s share of the

16 Ibid.

17 Seved ob~ms ~ve criticized NASA’S earlier budgeting as highly unrealistic. U.S. Congress, Gened ~comm ~lce

GAO/NSIAD-92-278, NASA: Large Programs May Consume Increasing Share of Linu”ted Future Budgets (WAingto% DC: U.S. General

Aeeounting Office, September 1992). Ronald D. Brunner, ‘‘Overmnm.it.rmmt at NAS~” presented at the annual American Astronautical

Society Conference, San Francisco, CA, December, 1992.

18 me dismetioq ~fion of the fiscal year 1993 federal budget request was $502 billion.
Chapter 2—Remote Sensing and the U.S. Future in Space I 19

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%

.-E

g

0

(xl m

7

0

1-

q

mu) N

0

e

mrN.

al

$

1-

0

0

a)

0

0m k

.-z

(8

c

.—

ii

ii3

In

. . . . . . . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

.

.

. . . . .

. . . . .

. . . . .

cm

v) .- .

.
20 I Remote Sensing From Space

2,000

0,000

8,000

1992 1993 1 994* 1 995* 1996”

Remainder

Physics, astronomy and planetary exploration

Research and program management

Mission To Planet Earth

Space shuttle

Space station and new technology investment

“Estimates

Large programs constitute most of NASA’S budget, leave Iittte

flexibility, and require a 13 percent budget increase between

FY93 and FY96.

SOURCE: NASA Budget Estimate, Fiscal Year 1994.

civilian space budget, should expect only modest

annual increases in its overall budget.19 Independent reviews of NASA’s budget prospects also

suggest that NASA may face lower future budgets.20 NASA’s budget in fiscal year 1992 was

$14.334 billion, a 3.4 percent boost over the fiscal

year 1991 budget (table 2-2).21 For fiscal year

1993, however, NASA’s budget is $14.330 billion. The Clinton Administration is requesting

$15.265 billion for NASA for fiscal year 1994, a

one billion dollar increase over the 1993 appropriation. 22

Figure 2-6 illustrates the required budget increase for NASA’s program plan. A level budget

(in current year dollars-i.e., one that decreases

as inflation rises), or a budget that is increased

only slightly, would produce a significant gap

between available funding and program needs.

Yearly budgets for MTPE may reach more than

9 percent of NASA’s total budget by 1995 (figure

2-7). If NASA neither receives large budget

increases nor further reduces the content of its

plans, 23 competition for funds within NASA’S

budget may force difficult choices among

Mission to Planet Earth and other major

projects, including those supporting the human

presence in space. For example, maintaining

NASA’s four largest programs at planned levels

under a flat agency budget of $14.3 billion in

fiscal year 1996 would require a 30 percent

reduction in the rest of NASA’s programs for that

year.

The primary competition for funding within

NASA is likely to be with programs supporting

the human presence in space, which today consume more than 70 percent of NASA’s budget for

19 ~~~e co~e~es Concw ~ tie Semte lmWge amem~g a series of principles designed tO adpst NASA’S m~titims ~d Smt@C

pl arming to leaner budget allocations in the coming years. ’ Conference Report on the 1992 Appropriations for the Veteran’s Administration

Housing and Urban Development, and Independent Agencies, House of Representatives Report 102-226 (to accompany HR. 25 19), Sept. 27,

1991, p. 54. The Senate language directs that “the agency should assume no more than 5 percent actual growth in fwcal year 1993:” Semite

Report 102-107, July 11, 1991 (to accompany H.R. 2519), p. 130.

20 For Cxmple, tie Elec~o~c ~d~~es Ass~iation for~~~ tit NASA’S budget will &op by about 8 percent h real terms over the neXt

4 years. Electronics Industries Association, Twenty-Eighth Annual EIA Ten-Year Forecast of DoD and NASA Budgets (Washington DC:

Electronics Industries Association October 1992).

21 Conw=s appmpfit~ $14.352 billion for tie NASA fisc~ y~budget but laterrescbded $18.4 million from Climmt ~d other projects.

22 me ~omt of ~ rquat i5 s~~ t. the previou5 aW5~ation’s rquest Of $14.993 bilfion for f~d y- 1!)93, which CO~tiS

reduced substantially.

23 sched~e s~tchou~ titf~ t. reduce program ~mmitmerl~ o~y ~Crease & to~ budget for a proj~t and create a “hw wave’ Of

fuhm budget needs,
——.—

Chapter 2–Remote Sensing and the US. Future in Space l21

Table 2-2—NASA Budgets (millions of then-year dollars)

1993 1994 1995 1996

1991 1992 Estimate Request Estimate Estimate

Space Station (and new technology) . . . . . . .

Space transportation capability

development . . . . . . . . . . . . . . . . . . . . . . . .

Mission to Planet Earth. . . . . . . . . . . . . . . . . .

Physics and Astronomy & Planetary

Expiration . . . . . . . . . . . . . . . . . . . . . . . . .

Life Sciences and Space Applications. . . . . .

Commerciai programs . . . . . . . . . . . . . . . . . . .

Aeronautical, Transatmospheric, and Space

research & technology . . . . . . . . . . :. . . . .

Safety, QA, academic programs, tracking

and data advanced systems . . . . . . . . . . .

Shuttle production & operations. . . . . . . . . . .

Expendable launch vehicle services . . . . . . .

Space communications . . . . . . . . . . . . . . . . .

Construction of facilities. . . . . . . . . . . . . . . . .

Research & program management . . . . . . . .

Inspector general . . . . . . . . . . . . . . . . . . . . . .

1,900.0 2,002.8 2,122.5 2,300.0 2,300.0 2,300.0

602.5

662.3

739.7

828.0

649.2

937.9

649.2

1,074.9

643.3

1,448.1

639.0

1,508.4

1,442.9

325.9

88.0

1,570.9

314.7

147.6

1,577.5

350.6

164.4

1,631.9

351.0

172.0

1,709.1

320.7

141.4

1,676.0

282.0

132.7

893.9 1,101.5 1,138.3 1,398.9 1,528.1 1,650.9

108.1

4,066.4

229.2

828.8

497.9

2,211.6

10.5

122.4

4,325.7

155,8

903.3

531.4

1,575.8

13.9

148.9

4,069.0

180.8

836.2

525.0

1,615.0

15.1

134.4

4,196.1

300.3

820.5

545.3

1,675.0

15.5

145.1

4,042.7

313.7

1,014.6

387.2

1,703.0

16.0

152.3

4,201.5

363.4

1,093.3

375.0

1,752.0

16.5

Agency summary . . . . . . . . . . . . . . . . . . . 13,868 14,334 14,330 15,265 15,713 16,143

SOURCE: National Aeronautics and Space Administration, 1992, 1993.

Figure 2-7-Composition of NASA’s Budget, 1990 and 1995

1990 NASA Budget 1995 NASA Budget

Station Station

Rest of NASA

39.5”/0

Rest of NAS

37.5Y0

Shuttle

30?/0

Shuttle

25.70/o

TOTAL: 12.295 TOTAL: 15.173

Note the growth of NASA’s major programs, including Mission to Planet Earth, which increase to neariy 9 percent of total budget.

SOURCE: NASA Budget Estimate, Fiscal Year 1994; Fiscal Year 1992.
22 | Remote Sensing From Space

space activities,24 primarily though the space

shuttle and space station Freedom programs.

25

Hence, if NASA’S overall budget remains flat

or includes only modest growth, unexpected

future increases in either of these two large

programs could squeeze MTPE to the point

that its effectiveness to support global change

research would be severely reduced. Extremely

stringent budget conditions would put Congress

and the Clinton administration in the position of

having to choose between a robust program that

tracks global change and manages Earth resources and a program that supports human

presence in space.

The risk of budget surprises related to the

support of humans in space is relatively high. As

noted in an earlier OTA report, ‘‘The United

States should expect the partial or total loss of one

or more shuttle orbiters some time in the next

decade [i.e., the 1990s].”26 As experienced after

the failure of Challenger in 1986, the costs of

such a loss could reach several billion dollars,

even neglecting the costs of repairing or replacing

the damaged orbiter.27 Losing an orbiter would

almost certainly delay construction of a space

station, causing much higher costs to that program.

Additional budget pressures on MTPE could

lead to the use of fewer advanced sensors and

other subsystems, or to technology choices that

would raise system operating costs. They could

also lead to smaller investments than planned in

the distribution and analysis of MTPE data.

Furthermore, satellite research and development

(R&D) projects, like most other efforts that

involve signficant technology R&D, tend to

grow in cost beyond initial estimates as engineers

and scientists face the complexities of design and

production, and delays that are beyond the control

of the project directors.28 Cost growth within the

MTPE satellite development and/or operations

programs also would probably reduce the quality

or quantity of scientific observations NASA is

able to accomplish.

Figure 2-8 indicates cost performance in the

major recent remote sensing ‘‘New Starts. ’ Four

of the five programs have encountered significant

cost increases over the original estimates presented to Congress at the time of program

approval (New Start).29 Some cost growth in

these programs is the result of additions or

changes in program content, while the majority of

cost growth is the result of cost increases at

contractors. The GOES-Next program has encountered the most substantial cost growth of

recent remote sensing programs, with development costs increasing more than two and one half

times original cost estimates since program approval by Congress. UARS, on the other hand,

was built and flown with no cost growth between

~ ~t @ excluding $911 million fOf =OtUUltiCS.

24 ~t is, excluding $911 dhOII for &iTOIltMltiCS.

U Du~t spending on space station Free&m and space shuttle dOne COnsum e nearly half of the total budget (table 1-2).

26 ~lm of TW~oloW Assessment &cess to Space: The Future of U.S. Space Tran.rportation sYStem (w-on, ~: us.

Government Printing Office, May 1990), p, 7. This is based on an assumption of shuttle launch reliability of between 97 and 99 percent (p.

45).

27 MIW of TtximoIogy Assessmen$ Access to Space: The Future of U.S. Space Transportation Systems (wN@ton.w: U.S.

Government Printing Oft3ce, May 1990), p. 21.

2s No~ble rw~t exceptions include the Upper Atmosphere Research Satellite, which was built within budget ~d on sc~ule.

29 FiWes include la~ch ~d operation estimates, except GOES, which d~s not include oP~tions. TRMM and EOS are not included, as

these programs have been in development a relatively short time.
.—

Chapter 2—Remote Sensing and the U.S. Future in Space |23

Figure 2-8-Cost Performance of Recent Remote

post-Challenger reprogr amming in 1986 and

spacecraft flight.30

Among these five recent remote sensing programs, cost increases average 55 percent. In total

dollars for all five programs, cost increase is 61

percent. Similar cost growth among EOS and the

planned remote sensing New Starts in the future

would have a significant adverse impact on the

future of remote sensing.

In order to reduce the risk to MTPE, NASA will

need to find ways to build in resilience to possible

future unforeseen circumstances that would cause

budget growth. In overseeing NASA’s allocation of funding for MTPE, Congress may wish

to examine how NASA plans to provide contingency funds and other means of ensuring

resilience for the program.

In attempting to find room in NASA’s budget

to retain EOS activities at a level at or near $8

billion between 1991 and 2000, Congress could

reduce funding for other individual programs,

including space shuttle, the advanced solid rocket

motor, space station, and space science.

However, in order to retain the existing budget

for Earth sciences research by cutting other

programs, NASA would either have to stretch out

some programs by a significant amount, thereby

increasing total program costs,31 find savings by

increasing efficiencies, or cancel some programs.

NOAA’S REMOTE SENSING BUDGET

NOAA will remain the primary collector of

satellite remote sensing data for both meteorological and climate monitoring efforts through the

decade of the 1990s. Thus, NOAA could play a

strong role in the satellite remote-sensing portion

of the USGCRP, while also maintaining g and

improving its traditional role.32

Yet many observers question NOAA’s capability and commitment to broader global change

research, as well as its ability to secure the

funding to support that research. Indeed, NOAA’s

yearly budgets experience strong competition

with other priorities within the Department of

Commerce and within Congress’ Appropriations

Subcommittee on Commerce, Justice, State, and

Judiciary.

Table 2-1 provides unofficial planning estimates for NOAA satellite remote sensing. NOAA

remote sensing budgets are currently expected to

remain in the range of $400 to $450 million per

year through the rest of the decade, with no major

w ReXom ~t~but~ t. UARS cost ~fio~nce SUCCIXS include: The UARS project had well-defined scientilc n%u~~enmt ad ~~ tie

multimission modular spacecraft employed earlier for the Solar Maximum Mission. It also used “plug-in” modules for propulsio%

communications, and navigation. Scientists and engineers in the UARS project were well aware of standard interfaces, and apparently no

exceptions were allowed by UARS management. The UARS project was also able to depend on steady, fill funding from the administration

and Congress, which in turn is essential for budget, capability, and schedule performance.

31 ~oj=~ tend to have an optimum pace at which to proceed in order to keep COStS at a minimum. Stretching projects as a result of yearly

bUdgeL limitations requires putting off parts of the project. Because NASA and its contractors must retain much of their experienced workforce

on a project, despite the stretched schedule many overhead costs continue, increasing the overall cost of a program.

32 NOAA ~long s~~ of con~uou5 records for fip~nt clfite v~ables such M snow cover, ice analysis, sea surface teMptTatie,

Earth radiation budget+ vegetation index, and ozone. Some of these observations date back to 1%6.
24 I Remote Sensing From Space

funding increases expected. This is in marked

contrast to the expansive satellite research efforts

underway at NASA. NOAA’s smaller increases

in yearly remote sensing funding would allow for

some relatively minor planned improvements in

POES satellites and instruments, and the completion and launch of improved GOES satellites (see

ch. 3: Weather and Climate Observations).

Highly constrained NOAA satellite remote

sensing budget requests have historically been the

norm, as illustrated by Administration attempts to

cut the POES program to one satellite, and the

termination of the Operational Satellite Improvement Program at NASA in the early 1980s (see ch.

3: Weather and Climate Observations). A more

recent example of the effects of limited funding in

NOAA is Congress’ $5.3 million cut in the

“environmental observing services’ line of the

1993 NESDIS budget request.

Recent efforts within NOAA to strengthen

advanced sensor research, oceanic remote sensing, and climate observations have been largely

unsuccessful. Continuing budget pressures have

hampered NOAA’s efforts to participate meaningfully in sensor design, mission planning, or

data analysis in U.S. and international efforts to

develop new satellite remote sensing spacecraft

and instruments in the 1990s. Yet these endeavors

could build on the substantial investment of other

agencies and countries for satellite system hardware to provide additional global change information. For example, NOAA has still not succeeded

in securing the relatively small resources (approximately $6 million) required to assure direct

receipt of vector wind data from the NASA

scatterometer instrument aboard the Japanese

ADEOS satellite,33 a potentially important enhancement of NOAA’s forecast capability.

Observers note that the outcomes of the yearly

budget process have caused NOAA’s operational

remote sensing program to ‘‘limp along from

year to year. Over the past decade, NOAA has

reportedly lost much expertise in remote sensing,

and lost some credibility among the user community. In sum, NOAA satellite remote sensing

funding appears to constrain NOAA’s ability

to serve U.S. needs for remotely sensed data,

especially considering the continued importance to the United States of meteorological

and long-term climate change data.

THE COSTS AND BENEFITS OF

SATELLITE REMOTE SENSING

Between fiscal years 1993 and 2000, the

United States plans to spend about $14 billion to

supply remotely sensed data form several systems, or an average of $1.75 billion per year. Such

data serve the U.S. economy by producing

information useful for predicting weather, managing natural and cultural resources, economic

planning, and monitoring the environment (table

2-3). They will also help scientists detect and

understand global change. Multiple systems are

needed to provide different kinds of information.

Although a systematic study of how costs and

benefits compare has not been conducted, costs

are likely to be small compared to the benefits that

could be obtained with better information generated from remotely sensed data. For example, as

noted above, knowing many hours in advance

which path a hurricane is likely to take has

allowed coastal dwellers to prepare their houses,

businesses, and public buildings for the onslaught, and has saved numerous lives as well as

millions of dollars in costly repairs. The management of rangeland, forest, and wetlands can also

benefit from the large-scale, synoptic information

that data form satellite systems can supply.

In the near future, global change research will

likely consume the largest share of the satellite

remote sensing budget. Here again, the gains in

increased knowledge about the effects of harmful

change could far outweigh the average yearly

costs for space-based global change research

(about $1 billion annually beginning in 1995).
Chapter 2–Remote Sensing and the U.S. Future in Space |25

Although estimates of the potential costs to

sectors of the world’s economy from global

change are uncertain, they do indicate that such

costs could range to tens of billions of dollars per

year for the United States alone (box 2-A).

Analysts predict, however, that some of the costs

to the U.S. economy from global warming, taken

alone, might be offset by the potential benefits.34

The Federal Government may wish to fund

programs to mitigate the effects of global change

or to adapt to it. The choices of how to respond to

the effects of global change, in large part, will be

determined by scientists’ ability to predict these

effects. Satellite remote sensing data alone will

not necessarily enable the United States to avoid

potential costs, but some fraction of the costs

might be saved with improved information derived from satellite data. Given the large investment the United States and other nations are

making in the provision of data from satellite

systems, Congress may want to request a

systematic study that would compare costs of

providing satellite data for monitoring the

environment and for global change research

with the expected savings better environmental information would provide. Such an

assessment could help allocate resources based on

the type of data and utility of their information

content.

DATA CONTINUITY, LONG-TERM

RESEARCH, AND RESOURCE

MANAGEMENT

To be effective in monitoring global change or

in supporting resource management, the delivery

of high-quality, well-calibrated, remotely sensed

data must be sustained over long periods. Certain

data sets, such as those related to Earth’s radiation

budget, should be acquired continuously over

decades. In some cases, data must also be

delivered with few or no gaps in the operation of

the satellites. For example, losing a Landsat

satellite more than a few months before a

replacement can be launched would force resource managers to find sources of other, possibly

less efficacious, data. Such a data gap would also

reduce the ability of global change researchers to

follow large-scale changes in the rain forests and

other elements of the biosphere.

The need for continuity of data collection and

use is recognized in the Land Remote Sensing

Policy Act of 1992, which states:

The continuous collection and utilization of

land remote sensing data from space are of major

benefit in studying and understanding human

~ F~~ ~-plc, ~~~ ~ff~t of glo~ w- ~u]d &to lengthen the ~OW@ WUon in Sreits that me nOW IIIM@@ thus improving the

income from agriculture and other seasonal industries. See William D. Nordhouse, “Economic Approached to Greenhouse Warming,” in

Rudiger Dombusch and James M. Poterlan, eds., Global Warm”ng:Economic Policy Respomes ( Cambridge, MA: The MIT Press, 1991), &2.
26 I Remote Sensing From Space

Box 2-A–Estimated Costs Resulting From Global Change

Determining the expected costs resulting from various scenarios of climate change is challenging. The

economic effects of climate change can be divided into two broad categories. If climate change does occur, every

country will endure costs of remediation and costs associated with coping with a changing environment. Costs of

remediation involve expenses incurred adapting to change and preventing further harmful emissions. For example,

included in remediation costs would be the expenses incurred for developing less polluting technologies. Adapting

to a changing environment might include the expense of developing new agricultural practices and seeds needed

to cope with changing climate and weather patterns. Costs are influenced by technology development, ability of

consumers to afford new technologies, government regulations, population growth, demographic trends, and

effectiveness of international treaties. Potential costs in several areas could be quite high:

. costs to agriculture could increase by $5.9 to $33.6 billion annually (1992 dollars);

. forests, a $13 billion industry whose costs could increase by $4 billion annually;

. species loss could lead to damages ranging from a few billion to an order of magnitude higher;’

. for the costs of sea-level rise, estimates range from $73 to$111 billion (1965 dollars-cumulative through

2100), to $373 billion associated with a one-meter rise, an additional $10.6 billion annually to cover

associated economic losses;2

. loss of wetlands, biological diversity, and water resources; and

. increased fuel and power requirements, $200-300 billion (1986 dollars)3

These and all cost estimates associated with climate change should be regarded with extreme skepticism.

The art of estimating the costs o f global change is still in its infancy. Most published estimates are predicting future

events that are not clearly defined and may not even occur. However, what is clear is that should our climate

change, the costs of change both in real and in opportunity costs could be enormous.

1 ~ll~m R. CIiM, TIW Econom~ of GIobsi Warming, Washington, DC: Institute for international Economics,

1992.

z ~ US, Environmental protection Agency, Iil’he Potential Effects of Gtobal Ciimate Change on th9 Unit9d

States,” December, 1989, and US. Environmental Protection Agency, “Changing Climate and the Coast,” 1980.

3 U.S. Environmental protection Agency, “The Potential Effects of Global Ciimate Change on the United States,”

December, 1989.

impacts on the global environment, in managing collection and use over decades. In order to be

the Earth’s resources, in carrying out national fully exploited, these calibrated data sets will

security functions, and in planning and conduct- have to be archived, maintained in good condiing many other activities of scientific, economic, tion, and made readily available to users.

and social irnportance.35

If Congress wishes to sustain U.S. efforts to DEVELOPING AND EXECUTING A

understand and plan for the effects of global — STRATEGIC PLAN FOR SPACE-BASED

change, prepare for more effective manage- REMOTE SENSING

ment of Earth’s resources, and support na- The expected constraints on NASA’s budget

tional security uses of remotely sensed data, it for MTPE speak to another important theme that

will have to give attention to funding programs has emerged during the continuing debate over

that would maintain the continuity of data U.S. space policy — how to accomplish the goals
Chapter 2—Remote Sensing and the U.S. Future in Space |27

for U.S. space activities more efficiently and with

greater return on investment. Decisions will be

made in an environment in which several U.S.

agencies, private companies, and foreign entities

pursue remote sensing activities. Greater program integration, both domestically and internationally, has the potential for reducing costs

and redundancy, but risks program delays,

compromises on goals, and increased cost. In

the past, the development of new or improved

satellite sensors and systems has proceeded according to the specific needs of the funding

agency. However, recent experience with data

from Landsat and from NOAA and DoD environmental satellites, as well as foreign satellites,

demonstrates that the utility of data from these

systems extends far beyond the interests of any

single agency. Responding to a broader set of

needs would likely increase the cost of any single

satellite system or sensor because it would put

more demands on the instruments and satellite

bus. However, increased capability might in time

increase the overall benefit of satellite remote

sensing to the U.S. taxpayer.

On the domestic level, the need to maximize

the return on investments in remote sensing,

particularly for global change research, which

dominates expected future spending on civilian remote sensing systems, suggests that

NASA, NOAA, DoD, and DOE should combine

efforts to develop a single, flexible strategic

plan that would:

●

●

●

guarantee the routine collection of highquality measurements of weather, climate,

and Earth’s surface over decades;

develop a balanced, integrated, long-term

program to gather data on global change that

includes scientifically critical observations

from aircraft and groundbased platforms, as

well as space-based platforms;

develop appropriate mechanisms for archiving, integrating, and distributing data from

●

many different sources for research and

other purposes; and

ensure cost savings to the extent possible

through incorporating new technologies in

system design developed in either the private

or public sectors.

Developing a single, flexible plan would require an assessment of whether and where programs of these agencies might conflict, and if so,

how they might be harmonized.

9 Collecting Routine Earth Observations

Operational, long-term remote sensing programs such as NOAA’s environmental satellite

programs and Landsat have generally suffered

budget neglect, while the Nation directs attention instead toward new spaceflight missions

supported through NASA’s budget. An integrated plan would improve the incorporation of

data from DMSP, GOES, POES, and Landsat into

operational government programs, as well as into

global change research.

The recent shift of operational control of the

Landsat system from NOAA to DoD and NASA,

as stipulated in the Land Remote Sensing Policy

Act of 1992,36 appears to support the routine,

long-tern provision of Landsat data for the

operational use of government, the private sector,

and international users. From now into the next

century, these data will serve as one of the

primary sources for information on the condition

of the land and coastal environments. Landsat

data will also enable the tracing of long-term,

gradual changes to Earth’s surface as a result of

climate change and/or anthropogenic environmental effects. However, if Congress and the

Administration wish to ensure continuity of

data delivery and the continued improvement

of Landsat sensors and system components,

they will have to maintain a more supportive

policy and funding environment for land
||— —

28 | Remote Sensing From Space

remote sensing than they have during the past

decade.

The private sector has developed a growing

market for remotely sensed data products, both as

buyer and seller, and is a major force in setting

standards for remotely sensed data and analytic

software. It has also created new data applications, and developed innovative sensors. In the

past, many private sector users of remotely sensed

data have complained that the government has not

taken their needs and interests into account when

designing new remote sensing programs. In

order to ensure that Landsat meets the needs

of private sector as well as government users,

Congress might wish to encourage DoD and

NASA to establish an advisory committee to

gather input from private industry and academia for building and operating remote sensing

satellites.37

For the United States to assure the continual

improvement of operational satellite systems,

it will need a new approach to developing new

sensors. In the past, NASA has generally developed remote sensing systems in response to a set

of research interests. As its interests change,

NASA’s focus on sensors and satellites change

with them.38 In the 1960s and 1970s, some

research instruments developed by NASA were

incorporated into NOAA’s environmental satellites and the Landsat satellites, all of which serve

abroad clientele from government and the private

sector. However, in recent years, as exemplified

by the experience with the development of

NOAA’s GOES-Next geostationary satellite (see

ch. 3: Weather and Climate Observations), the

previous arrangement for close cooperation between NASA and NOAA has broken down .39

1 Global Change Research

In order to be effective in fully understanding

Earth systems, global change research requires

detailed data about chemical and physical processes in the atmosphere, oceans, and land. Some

research problems, particularly those that involve

modeling Earth’s atmosphere, also require data

taken over decades. In order to make the most

efficient use of funding resources, the longterm research goals of U.S. global change

research must be well coordinated across

agencies and with academia. There should also

be appropriate means to allocate funding

among agencies. The USGCRP has served an

important function in focusing the activities of the

different agencies toward global change research,

but it has relatively little power to adjudicate

differences among agencies or to bring discipline

to funding decisions. National Space Policy

Directive (NSPD) 7, issued on June 1, 1992,

established the Space-based Global Change Observation System (S-GCOS), under the aegis of

USGCRP, to coordinate the satellite-based global

change studies of U.S. agencies.

“In support of the USGCRP the S-GCOS shall:

●

●

Improve our ability to detect and document

changes in the global climate system to

determine, as soon as possible, whether there

is global warming or other potentially adverse global environmental changes; and, if

changes are detected, determine the magnitude of these changes and identify their

causes.

Provide data to help identify and understand

the complex interactions that characterize

the Earth system in order to anticipate

37 F~~ ~.pie, he ~~d R~Ote s~~g pO@ Act of 19~ ~n~tes tie ~lici~tion of advi~ from “a broad range of perspectives . . .

[including] the full spectrum of users of Landsat data including representatives from United States Gov ernrnent agencies, academic institutions,

nonprofit organizations, value-added companies, the agricultural, mineral extraction, and other user industries, and the public; Section 101 (c)

Landsat Advisory Process.

38 ~mNASA ~M d~velop~ tie L~&at sties ofsurfacxremote sensing satellites in the 1970s, some bm UWH comp~ed ~tNASA’s

shift of data formats made it difficult for tbem to plan on routine use of the data.

39 ~ment Ofcomexe, Office of~e qtor General, National Strategy for Satellite Remote Sensing iSMwkci, qubfish~ W%

Febmary 1991.
Chapter 2–Remote Sensing and the U.S. Future in Space |29

changes and differentiate between humaninduced and natural processes.

. Provide for a data system to manage the

information collected by S-GCOS as an

integral part of the Global Change Data and

Information System, consistent with the

USGCRP data policy.

. Provide for the development and demonstration of new space-based remote sensing

technologies for global change observation

and identify candidate technologies for future operational use. ’ 40

NASA was assigned the lead role in S-GCOS.

NSPD7 directs other agencies—including the

Departments of Defense, Energy, and Commerce

to cooperate in the development and operation of

spacecraft and data systems. Because S-GCOS is

a recent creation, and because of the recent

change of executive branch administration, it is

too early to judge its effectiveness in guiding the

direction of global change research and other

aspects of U.S. satellite remote sensing programs.

However, because S-GCOS creates a forum

where agencies can share information about

existing and future plans for space-based global

change research, it has the potential to reduce

redundancy and lead to greater sharing of limited

resources.

I Improving the Use of Data

The need to be more efficient in using resources dictates greater attention to the ground

portions of these programs, which are historically

relatively inexpensive compared to procuring

new spacecraft and instruments. Although NASA

has demonstrated the ability to collect data

from a variety of instruments, it has been less

successful in making effective use of them.

Historically, data from remote sensing systems

have been underutilized, while funds that

might be used for data analysis are instead

funneled toward the next generation of spacecraft.

NOAA and NASA have not made sufficient

use of NOAA’s rich data archives for global

change research. The Landsat archives held at

the U.S. Geological Survey’s EROS Data Center

are also underutilized for global change research.

Such inattention to effective data management

and use could undermine global change research

efforts, particularly NASA’s Earth Observing

System (EOS), the largest component in its

MTPE program.

Scientists participating in the MTPE have

pressed for close attention to the development of

a powerful system to store, distribute, and analyze

data collected from the various U.S. and international sensors that will contribute to global

change research. As a result, NASA is developing

the Earth Observing System Data and Information System (EOSDIS), which will be composed

of several interconnected data archives distributed around the country (figure 2-9).41 As part of

its EOSDIS efforts, NASA has funded the development of data sets composed of data gathered over

the past two decades from sensors aboard the

Landsat satellites and form the NOAA operational environmental satellites. NASA’s early

experience in developing these ‘pathfinder’ data

sets illustrates the difficulties NASA may encounter in dealing with the massive amounts of data

from the EOS satellites.42 It also helps NASA

resolve many difficulties before EOS becomes

operational. Scientists working on the project are

finding it much more difficult than they anticipated to process the data to make them useful to

global change researchers. NASA’s and NOAA’s

@ Nation~ Space Policy Dirmtive 7: Spam-ked Global Change Observations. The White House, signed by Resident Bum 1 June 1992.

This NSDD, which attempts to improve coordination and collaboration in global change researc~ originated in the National Space Council.

41 Hu@es Applied Information Services, Inc. won the contract to develop EOSDIS.

42 us. conps~, General &-cou@ ~lce, GAO-C.92-79, Ea~h Obsewing system: Information m NAM’s Incorporation Of

Existing Data Into EOSDL$ (W%shingto% DC: General Accounting Office, September 1992).
30 | Remote Sensing From Space

Figure 2-9—The EOSDIS Network

I ORNL

Ground-based

EDC I data relating

Land processes to biogeochemical

Imagery dynamics

(

SOURCE: National Aeronautics and Space Administration.

efforts on the pathfinder data sets also make clear

that these data have been underutilized for global

change research.

A future report in this assessment will treat data

issues in detail. Improving the return on investment in U.S. remote sensing systems will

require more efficient use of existing remote

sensing data acquired by satellite. It will also

require making more efficient use of data

acquired by other means, such as data that

could be taken by aircraft, balloons, UAVS, or

from groundbased installations. These data

are important for remote sensing instrument

calibration and validation.

9 Institutional Issues

U.S. research and operational remote sensing

activities cut across disciplinary and institutional

boundaries. Although existing institutional mechanisms are likely to improve the coordination

of U.S. research and operational remote sensing activities, they are unlikely to be sufficient

to develop a long-term integrated plan that

allocates resources among the agencies. Because funding and resource decisions rest largely
Chapter 2–Remote Sensing and the US. Future in Space | 31

with each individual agency and its respective

congressional committees, no mechanism exists

to enforce collaboration among agencies or adjudicate differences that are likely to arise. Congress may wish to establish an institutional

mechanism to make resource allocation recommendations about remote sensing that extend

across agency boundaries. The Office of Science and Technology Policy, might be given this

role. However, as presently constituted, the Office lacks the staff and the mandate to resolve

differences among agencies. OMB might be able

to assume such a task, but it suffers from a lack of

staff and expertise. In addition, it is highly

departmentalized. OTA will examine this and

other organizational and institutional issues in a

future report, which will develop a set of options

for Congress to consider.

Greater international coordination and collaboration on sensors and systems, as well as data

types and formats, will eventually be needed in

order to reap the greatest benefit from the

worldwide investment in remote sensing technologies (see ch. 8: International Cooperation and

Competition. Sensors on existing satellites provide considerable overlap in capability. Although

some redundancy is appropriate in order to give

engineers and scientists in different countries

experience in designing, operating, and using

remote sensing technology, eventually the international community as a whole would be best

served by reducing overlap43 as much as possible

and by using the available funds to improve the

application of the data or to provide additional

capability. The United States and Europe, which

are now headed toward the goal of building and

operating a single system of two polar orbiting

satellites (see ch. 3: Weather and Climate Observations), might consider including Russia in their

plans. The United States and Russia now operate

polar orbiting satellites. Closer cooperation between the United States, Europe, and Russia

could lead to the development and operation of a

single, more capable polar orbiting system. Because of the precarious state of the Russian

economy, this might initially require supportive

funding from the United States and other countries.

The countries that operate Earth observation

satellites have established two mechanisms to

foster greater cooperation-the Committee on

Earth Observations Systems (CEOS) and the

Earth Observation-International Coordination

Working Group (EO-ICWG). Both were deliberately created as informal organizations in order to

avoid confronting administrative hurdles within

each country that a more formal cooperative

structure might engender. Countries use CEOS

and EO-ICWG to inform members about their

plans and to coordinate Earth observations. There

is no exchange of funds.

In the future, the United States may wish to

consider leading a broadbased cooperative

program to collect, archive, and distribute

long-term environmental data sets using sensors and satellites systems similar to those now

operated by NOAA.44 If properly structured,

such an international system could involve the

funding and talents of many more nations in

building and operating a system. It would also

increase our capability to gather and process

environmental data sets over the long term. The

final report of this assessment will examine the

benefits and drawbacks of a broadbased international polar-orbiting system, as well as the related

issue of closer cooperation on NOAA’s geostationary satellite system.

43 some ~valq ~ we fom of r~m~ncy IS ~e~ in order to provide appropriate backups for failed spacecraft or to provide ad~tio~

coverage. The use of the European Meteosat-3 spacecraft to provide backup for the aging U. S. geostationary environmental satellite, GOES-7,

is a case in point.

u John McEhoy, “The Future of Eartb Observations in the USA,’ Space Policy, November 1987, pp. 313-325.
and the

M

Weather

and

Climate

Observations

any variables determine weather. For example, atmospheric pressure, temperature, and humidity at different

altitudes affect the development and progress of storm

systems, the amount of precipitation a region receives,

number of cloudy days. Over time, these factors

contribute to the climate on local, regional, and global scales.

Throughout the day, sensors located on the land and oceans and

in the atmosphere and space:

●

●

●

●

●

take measurements of atmospheric temperature and humidity (essential to understanding weather systems and storm

development);

monitor atmospheric winds (providing critical information

on weather patterns);

take visible-light and infrared images of cloud formations

and weather systems;

monitor changes in solar radiation; and

measure concentrations of important atmospheric constituents.

Data gathered by these sensors are essential to understanding

weather and climate. Despite efforts to date, large gaps still exist

in scientists’ understanding of the detailed mechanisms of

weather and climate and in their ability to predict how weather

and climate will change, Climatologists would like more data on

atmospheric chemistry and dynamics, the extent of clouds, winds

at the oceans surfaces, and upper atmosphere winds. As the

recent concern over the degradation of Earth’s protective ozone

layer demonstrates, human activities alter atmospheric chemical

constituents and affect the structure and health of the atmosphere.

3
34 I Remote Sensing From Space

Box 3-A-NOAA’s Geostationary Satellite System

The Geostationary Operational Enviromnetal Satellites (GOES) maintain orbital positions over the same

Earth location along the equator at about 22,300 miles above Earth, giving them the ability to make nearlyconstant

observations of weather patterns over and near the United States. GOES satellites provide both visible-light and

infrared images of cloud patterns, as well as “soundings,” or indirect measurements, of the temperature and

humidity throughout the atmosphere. These data are essential for the operations of the National Weather

Service-such data provide advance warning of emerging severe weather, as well as storm monitoring. The

vantage point of GOES satellites allows for the observation of large-scale weather events, which is required for

forecasting small-scale events. Data from GOES satellites may be received for free directly from the satellite by

individuals or organizations possessing a relatively inexpensive receiver.

In order to supply complete coverage of the continental United States, Alaska, and Hawaii, the GOES

geostationary satellite program requires two satellites, one nominally placed at 75° west longitude and one at 135°

west longitude. The first SMS/GOES was placed in orbit in 1974. However, from 1984-1987 and from 1989 to the

present time, as a result of sensor failures and a lackof replacements, only one GOES satellite has been available

to provide coverage. GOES-7 is currently located at 1120 west longitude, which provides important coverage for

the eastern and central United States. Unfortunately, this single satellite is nearing the end of its “design life” and

could fail at anytime, leaving the United States with no GOES satellite in orbit. The United States has borrowed

a Meteosat satellite from Europe to cover the East Coast and serve as a backup should GOES-7 fail. Meteosat-3

is now positioned at 75° west longitude.

SOURCE: National Oceanic and Atmosphere Administration and Office of Technology Assessment, 1993.

By closing these data gaps, scientists hope to NOAA’s OPERATIONAL ENVIRONMENTAL

understand the forces that affect Earth’s weather SATELLITE PROGRAMS

and determine its climate. They also hope to

differentiate natural variability from anthropogenic changes in weather and climate.

Satellite sensors offer wide, repeatable coverage, long-term service, and the ability to monitor several aspects of weather and climate simultaneously. Data from satellites contribute to both

short- and long-term weather prediction and

modeling and enhance public safety. In the short

run, images of weather systems, obtained primarily from satellites in geosynchronous orbit,

allow forecasters to predict the probable paths of

severe storms. Data collected by polar orbiting

satellites concerning the atmosphere, land, and

oceans, are invaluable for understanding and

modeling atmospheric temperature, humidity,

wind, and the extent and condition of global

vegetation (plate 3).

As noted earlier, NOAA operates two satellite

systems to gather data concerning weather and

climate in order to support the national economy

and promote public safety.

 The GOES System

To provide complete U.S. coverage, NOAA

normally maintains two GOES satellites in orbit

(box 3-A). However, difficulties experienced in

constructing the next series of GOES satellites,

GOES-Next, and the lack of a backup for the

current series, have left the United States dependent on a single satellite, GOES-7, the last in the

current series. To maintain critical weather observations over the United States, NOAA has signed

an agreement with ESA and Eumetsat (box 3-B),

the European Organisation for the Exploitation of

Meteorological Satellites,l to lend the United

1 Eumetsat is an intergovernmental organization that operates meteorological satellites. Its satellite systems were developed and built by

the European Space Ageney.
Chapter 3-Weather and Climate Observations |35

Box 3-B—ESA and Eumetsat

The European Space Agency (ESA), a consortium of 13 member states,l has been in existence since 1975.

ESA has developed and launched weather satellites and Earth remote sensing satellites. ESA has developed two

experimental Meteosat spacecraft and an operational series of Meteosats. It is the primary agency responsible

for developing remote sensing spacecraft in Europe and plays a major role in coordinating European remote

sensing efforts. ESA develops and operates weather monitoring satellites on behalf of the European Organisation

for the Exploitation of Meteorological Satellites (Eumetsat).2 Eumetsat is an intergovernmental organization,

established by an international convention that states its primary objective:

. . . to establish, maintain and exploit European systems of operational meteorological satellites,

taking into account as far as possible the recommendations of the World Meteorological

Organization. 3

Some of the same issues that confront NASA and NOAA challenge ESA and Eumetsat. For example,

Eumetsat has struggled to clarify its mission with regard to weather forecasting and research. ESA has recentiy

decided to split its payloads between two different copies of a modular polar orbiting spacecraft, one in 1998 for

scientific research and a second in 2000 for weather forecasting. Eumetsat heralds this decision, which has

extended the organization’s mission to environmental research, as leading to a dearer distinction between

environmental experimentation and operational meteorology.4

1 Austria, Be/gjljm, ~nrnark, Germany, France, Ireland, Italy, The Netherlands, No~ayt SPain, Sw*m

Switzerland, and the United Kingdom; Canada and Finland are associate members.

2 Eumetsat has 16 members, including Finland, Greece, Portugal, Turkey, and the ESA ~mbrs excluding

Austria.

3 EUMETSAT ~nvention, Arti~le 2, 1986.

4“Eumetsat Likes Idea of Separate Polar Satellites,” Space News, June 22, 1992, p. 23,

SOURCE: Office of Technology Assessment, 1993.

States Meteosat-3 to supplement observations

from GOES-7 and to stand in should GOES-7 fail

(figure 3-l). This arrangement illustrates the high

level of international cooperation in meteorological remote sensing, which is carried out in other

areas as well. Because weather patterns move

across national boundaries, international cooperation has been an important component in

the collection of weather data. Governments

need to cooperate with each other in order to

follow weather patterns that transcend national boundaries.

GOES-7 is currently operating well, but it and

Meteosat-3 are about one year past their design

lives. The first satellite in the series of GOESNext satellites is scheduled for launch in spring

1994 (figure 3-2). The follow-on GOES-Next

satellite has been plagued by technical and

programmatic setbacks that, until the sumrner of

1992, led to major schedule slips and large cost

overruns. Changes in management have resulted

in controlled costs and good schedule success.

However, until GOES-Next has been successfully

launched and placed in operation, the United

States faces the risk of losing weather information

now provided by geosynchronous satellites.

During the early 1980s, in an effort to improve

the satellite data available to the National Weather

Service, NOAA funded and NASA developed

new, more complex sensor and satellite designs

for the GOES series. NOAA termed the new

satellite series GOES-Next. GOES-Next will

retain the existing visible imaging but also will

provide higher resolution infrared imagery to

enhance the prediction and monitoring of severe

weather. A separate, continuously operating im-
36 I Remote Sensing From Space

Figure 3-1-Meteosat-3 Images of Earth

These images were made before and after ESA moved Meteosat-3 westward from its earlier position near 500 west longitude to

its current position at 75o west longitude. Meteosat 3, launched in 1988, served as Europe’s operational satellite until June 1989,

when it was placed in on-orbit storage. In August 1991 ESA reactivated the satellite and moved it from 00 west to 5@ west to

supplement the U.S. GOES system. Beginning January 27, 1993, ESA moved the satellite 1° per day until it reached 75°, where

the second image was taken.

SOURCE: National Oceanic Atmospheric Administration, European Space Agency, Eumetsat.

proved atmospheric sounder2 should allow for

uninterrupted data on the atmosphere, contributing to improved storm prediction.

NOAA and NASA have a history of more than

30 years of cooperation on environmental satellites. NASA developed the frost TIROS polar

orbiting satellite in 1960, and in 1974 it launched

SMS-GOES, the precursor to NOAA’s GOES

system. Generally NOAA has relied on NASA to

fund and develop new sensors, several of which

NOAA adopted for its environmental satellites. A

1973 agreement between NASA and NOAA

resulted in the Operational Satellite Improvement

Program (OSIP) within NASA, which provided

funding at the rate of some $15 million per year

to support development of new sensors and other

technologies to improve NOAA’s operational

satellites. In the 1970s, highly successful cooperation between NASA and NOAA resulted in the

development of several sensors, including the

Advanced Very High Resolution Radiometer

(AVHRR) and the Total Ozone Mapping Spectrometer (TOMS).3 During the early 1980s, in an

attempt to cut its spending on satellite development, NASA eliminated spending on OSIP,

leaving NOAA to fund development of GOESNext, using NASA as the procurement agency.

Problems with program management, unexpected

technological challenges, and overly optimistic

bids accepted from contractors have caused the

development of GOES-Next to exceed its original

estimated costs by over 150 percent (box 3-C).4 If

Congress wishes NASA to continue to engage

in research and development for NOAA’s

2 A ‘‘sounder” is a sensor that provides data leading to estimates of temperature throughout the atmosphere.

3 A~ and TOMS provide important data on weather, climate, and global change research. See Box 1-G below for descriptions of these

sensors.

d Including launch costs, the GAO has calculated that the GOE!S-Next progrw including development and construction of five satellites,

will cost almost $1.8 billiou compared to its original estimate of $691 million.
Chapter 3-Weather and Climate Observations I 37

Figure 3-2—Engineering Drawing of GOES-Next

Solar

array

Telemetry and

control antenna

S-band transmit antenna

Sounder cooler

Sounder

Imager

GOES-Next is the new generation of meteorological satellites developed for NOAA and built by Ford Aerospace. The satellite

series features improved sounders and imagers, and will serve as the primary observation platform for NOAA after a much-delayed

1994 launch.

SOURCE: National Oceanic and Atmospheric Administration.

operational sensors and satellites, it could

direct NASA to reinstate the OSIP budget line

for sensor development and provide sufficient

funds to support OSIP. In addition, Congress

could direct NASA and NOAA to develop a

more effective relationship for the development of new operational systems. Alternatively, Congress could fund NOAA sufficiently

to allow NOAA to develop its own advanced

sensors. However, the latter option would require

that NOAA develop sufficient expertise in satellite design and development to manage new

development projects, which would likely cost

more than directing NASA to take on the task

again.

~ The POES System

The POES program (box 3-D), like the GOES

program, employs a two-satellite system. One

polar orbiter repeatedly crosses the equator at

approximately 7:30 am local standard time (the

‘‘morning’ orbiter) and the other satellite crosses

the equator at approximately 1:30 pm (the “afternoon’ orbiter). Although NOAA’s funding for

the POES system has been highly constrained by

tight NOAA budgets and by cost overruns of the

GOES program, NOAA has nevertheless managed to keep two operating satellites in orbit at all

times. 5 At the same time, it has actively sought

international cooperation as a means of spreading

the burden for providing important information to

all countries of the world, and as a means of

reducing U.S. costs.

For the future, NOAA is considering incorporating several of the instruments NASA has under

development for the Earth Observing System in

its operational satellites. For example, the Atmospheric Infrared Sounder (AIRS), planned as a

s Ln the 1980s, as a cost-cutting measure, the Reagan Administration regularly deleted funding for NOAA’s morning orbiter, but Congress

re-appropriated the funding each year.
38 | Remote Sensing From Space

I

high-resolution instrument that will provide tem- and the data they provide in order to transfer them

Box 3-C Lessons learned From the GOES Experience

The GOES system has been widely praised for its abilities to track both slow moving weather fronts and

rapidly developing violent storms. GOES is credited with saving many lives since the first satellite was launched

in 1975. For example, GOES images have contributed to improved early warning of violent storms, resulting in

a global 50 percent decrease in storm-related deaths. Yet the development of the GOES follow-on, called

GOES-Next, has met anything but calm weather. GOES-Next has been beset by management and technical

problems that have resulted in a large cost overrun.1

NASA and NOAA have a long history of cooperation in developing spacecraft. An agreement between the

two agencies, originaily signed in 1973, gives the Department of Commerce and NOAA responsibility for operating

the environmental systems and requires NASA to fund development of new systems, and fund and manage

research satellites. This NASA line item is known as the Operational Satellite Improvement Program, and was

usually funded at an average level of about $15 million per year.2 Prior to initiating GOES-Next development, this

division of labor seemed to work well. NASA had developed the TIROS and Nimbus research satellites, which carry

instruments that were eventually transferred to NOAA operational satellite systems. NASA and NOAA budgets and

organizational structure were based to an extent on the agreed-upon division of responsibility.

NASA and NOAA cooperation became less effective over time. During the transition to the Reagan

Administration in 1981, NASA faced cost overruns with ongoing programs and began to spend more of the

available resources, including the line item that was used for NOAA development, on the Space Shuttle. In

addition, the Reagan Administration was slow to appoint senior agency management in NASA. As internal

pressures mounted, NASA decided not to fund development of NOAA operational sensors and spacecraft. With

the concurrence of the Office of Management and Budget, NASA eliminated the budget line used to fund

development of new sensors for NOAA systems.

The GOES satellites operating at the time had life expectancies that would carry the program through the

late 1980s. NOM decided to build a GOES follow-on by 1989 that included a major design change. The system

requirements led to a very sophisticated design. NOAA wanted to improve the sensor’s visible and infrared

resolution and to operate the sounder simultaneously with the imager. In responding to a GAO investigation of the

GOES program, NASA officials agreed that NOAA’s requirements would be hard to meet.3 In an effort to shave

1 G~~~fi ~s O@i~IIy w at a~~ $&O million; estimat~ tot~ costs are now over $1.7 biiiion, including

iaunch costs, which shouid average neady $100 miiiion per iaunoh.

2 TMS figure was significantly higher durfng the eaffy 1970s.

3 U.S. - Acco@~ng ~~, ‘~at~ ~teliit~: Acth - to R~w ~atw of t~ U.S. eatio~ry

Sateilite Program,” Report to the Chairman, Committee on science, Spaoe, and Technology, House of Representatives,

July 1991.

perature and humidity profiles through clouds, to operational use. NASA will also have to take

would be a candidate for use on future NOAA into account the instrumental characteristics necessatellites. 6 However, NOAA will have to gain sary for developing an operational sensor. NOAA

extensive experience with the NASA instruments is also investigating other new instruments to

6 AIRS will measure outgoing radiation and be able to determine land surface temperature. In addition+ the sounder will be capable of

deterrninin g cloud top height and effective cloud amount+ as well as perform some ozone monitoring.
Chapter 3-Weather and Climate Observations |39

costs, NOAA eliminated the Phase B engineering review, an evacuation of satellite design and design changes.4

What was not clear to NOAA program managers at the time was how great a departure from the original design

was required. NOAA was confronted with the following in deciding how to replace the GOES-D satellite:

● NASA established a policy that future NOAA satellites should be designed to be launched by the Shuttle.

The existing GOES design, optimized for launch on an expendable launch vehicle, was not. NASA’s policy

was subsequently revised after the Challenger disaster in 1986, but the new design (GOES-Next) had

already been locked in.

. Several of the early GOES satellites had not demonstrated adequate reliability, failing earlier than

expected. This forced a decision to advance the procurement schedule.5

. Since NOAA was traditionally an operational entity, it had little hope of receiving approval for satellite R&D

funding, yet was pressed to proceed with a follow-on NASA procurement.

● Satellite manufacturers, though aware of the problems with the original GOES design, stated that providing

simultaneous imaging and sounding could be incorporated with only modest risk. NOAA and NASA

managers were skeptical of these claims, but they also needed to proceed quickly with the new design.

. A detailed interim engineering review for the GOES-Next plan was canceled for budget reasons. This

review might have revealed some of the problems contained in the original design.6

These factors complicated the decision to proceed with the improvement to GOES, which became known

as GOES-Next. The design change dictated by launch capabilities was unavoidable, given NASA’s launch policy.

NOAA proceeded with an ambitious effort that camouflaged some of the risk involved with developing GOES-Next.

Nothing in the history of either of the contractors involved (Ford Aerospace7 and ITT) indicated they were less than

qualified for the task.

The experience with GOES-Next highlights the problems of interagency cooperation within the U.S.

government. When NASA stopped funding development of operational satellites, agency responsibilities were no

longer dear. Funding authority for development of future operational satellites needs to be clarified.

4 Eric J. krner, “Goes-Next Goes Astray,” AeruspaceAIWMXL May 1992*

5 The ea~y GOES satellites (D-H) were plagued with the same pd)fem-a Small component that was essential

to determining the direotion of the field of view of the VAS sensor prematurely failed. The problem was eventually

overcome, but not before NOAA was faced with an earty replacement for two of its operational satellites.

6 krner, op. cit., footnote Is.

7 NOW part of kral Corporation.

SOURCE: Office of Technology Assessment, 1993.

improve the quality of its POES data collection.7

Over the years, NOAA has established an enormous

base of international data “customers” who

depend on the delivery of data of consistent

standards and familiar formats. It therefore carefully considers any changes to the format and

eschews technical or financial risks to its operations.

The United States historically has transmitted

data form the polar metsats at no cost to thousands

of U.S. and international users, who collect data

using inexpensive Automatic Picture Transmission (APT) recorders or High Resolution Picture

Transmission (HRPT) recorders as the satellite

passes over. Some 120 governments and thousands of other users around the world benefit from

7 For example, NOAA and Eumetsat are supporting research on the Interferometer Temperature Sounder (ITS) by the University of

Wisconsin and Hughes Santa Barbara Research.
40 | Remote Sensing From Space

Box 3-D-NOAA’s Polar-Orbiting Operational Environmental Satellite System

The POES satellites follow orbits that pass dose to the north and south poles as Earth rotates beneath them.

They orbit at about 840 kilometers altitude, providing continuous, global coverage of the state of Earth’s

atmosphere, including essential parameters such as atmospheric temperature, humidity, cloud cover, ozone

concentration, and Earth’s energy budget, as well as important surface data such as sea ice and sea surface

temperature, and snow and ice coverage. All current and near-future POES satellites carry five primary

instruments:

1,

2.

3.

4.

5.

The Advanced Very High Resolution Radiornefer/2 (AVHRR/2) determines aloud cover and Earth’s

surface temperature. This scanning radiometer uses five detectors to create surface images in five

spectral bands, allowing multispectral analysis of vegetation, clouds, lakes, shorelines, snow, and ice.

The High Resolution Infrared Radiation Sounder (HIRS/2). HIRS/2 measures energy emitted by the

atmosphere in 19 spectral bands in the infrared region of the spectrum, and 1 spectral band at the far red

end of the visible spectrum. HIRS data are used to estimate temperature in a vertical column of the

atmosphere to 40 km above the surface. Data from this instrument can also be used to estimate pressure,

water vapor, precipitable water, and ozone in a vertical column of the atmosphere.

The Microwave Sounding Unit (MSU) detects energy in the troposphere in four areas of the microwave

region of the spectrum. These data are used to estimate atmospheric temperature in a vertical column up

to 100 km high. Because MSU data are not seriously affected by clouds, they are used in conjunction with

HIRS/2 to remove measurement ambiguity when clouds are present.

The Space Environment Monitor (SEM) is a multichannel charged-particle spectrometer that measures

the flux density, energy spectrum, and total energy deposition of solar protons, alpha particles, and

electrons. These data provide estimates of the energy deposited by solar particles in the upper

atmosphere, and a “solar warning system” on the influence of solar fluctuations on the Earth system.

The ARGOS Data Collection System (DCS) consists of approximately 2,000 platforms (buoys,

free-floating balloons, remote weather stations, and even animal collars) that transmit temperature,

pressure, and altitude data to the POES satellite. The onboard DCS instrument tracks the frequency and

timing of each incoming signal, and retransmits these data to a central processing facility. The system is

able to determine transmitter location rather accurately.

Other instruments do not fly on every POES mission. Instruments in this category include:

The Stratospheric Sounding Unit (SSU), a three channel instrument, has flown on all NOAA POES satellites

except for NOAA-1 2. It measures the intensity of electromagnetic radiation emitted from carbon dioxide at

the top of the atmosphere, providing scientists with the necessary data to estimate temperatures through the

stratosphere. The SSU is used in conjunction with HIRS/2 and MSU as part of the TIROS Operational Vertical

Sounder System.

The Solar Backscatter Ultraviolet Radiometer/2 (SBUV/2) measures concentrations of ozone at various

levels in the atmosphere, and total ozone concentration. This is achieved by measuring the spectral radiance

of solar ultraviolet radiation “backscattered” from the ozone absorption band in the atmosphere, while also

measuring the direct solar spectral irradiance. The SBUV is flown on POES PM orbiters only.

The Search and Rescue Satellite Aided TrackingSystern (SARSATorS&R)kxates signals from emergency

location transponders onboard ships and aircraft in distress, and relays these data to ground receiving

stations, which analyze them and transmit information to rescue teams in the area.
Chapter 3-Weather and Climate Observations |41

The Earth Radiation Budget Experiment (ERBE) was flown only on NOAA-9 and NOAA-10. This research

instrument consists of a medium and wide field-of-view nonscanning radiometer, operating in four channels

that view the Earth and one channel that views the sun, and a narrow field-of-view scanning radiometer with

three channels that scan the Earth from horizon to horizon. ERBE measures the monthly average radiation

budget on regional to global scales, and determines the average daily variations in the radiation budget.

NOAA currently has four POES satellites in orbit. NOAA-11 and NOAA-12, launched in September 1988 and

May 1991, respectively, are operational, while NOAA-9 and NOAA-10, launched in 1984 and 1986, are essentially

in a stand-by mode. However, the ERBE instrument on NOAA-9 continues to return limited data on the Earth’s

radiation budget, and the SBUV/2 instrument on NOAA-10 continues to return useful information on ozone

concentration in the atmosphere. NOAA plans to upgrade several of the POES instruments in the near future. The

SSU and MSU will be replaced with the Advanced Microwave Sounding Units (aboard NOAA K-M), AVHRR will

gain an additional channel, and the ARGOS system will have expanded capacity. NOAA is planning additional

improvements (in the latter part of the 1990s) to AVHRR, HIRS, and AMSU and expects to add a Total Ozone

Mapping Spectrometer (TOMS) to the platform.

NOTE: The SSU is contributed by the United Kingdom; ARGOS is a contribution of the Freneh Space Ageney CNES; and the SARSAT

instrument is a joint project of Canada and France.

SOURCE: Office of Technology Assessment, 1993.

this service.8 In return, through the World Mete- data on the European METOP polar platform.

orological Organization,9 many of these users

provide the United States with local ground-based

and radiosondel0” data, which are essential to

understanding large-scale weather patterns and

climate. Some countries contribute directly to

U.S. programs by supplying satellite instruments.

Over the last few years, France has supplied the

ARGOS onboard data collection receiver, and,

with Canada, the SARSAT location system for

the POES satellites; the United Kingdom has

supplied the SSU.

Negotiations are currently underway between

NOAA, representing the United States, and ESA

and Eumetsat for Europe to assume responsibility

for morning-crossing operational meteorological

originally, Europe had planned to fly a large polar

orbiting platform called POEM (Polar Orbit Earth

Observation Mission), planned for launch in

1998. It would have included both research

instruments and operational monitoring instruments. However, in order to reduce technical and

financial risk, ESA and Eumetsat decided in late

1992 to split up the platform and place the

operational and climate monitoring instruments

on the Eumetsat METOP platform and the upper

atmosphere, ocean, and ice research instruments

on the ENVISAT platform.11 The United States

will also fly an improved AVHRR and an

Advanced Microwave Sounding Unit (AMSU)

on METOP- 1, which is planned for launch in

s The reception and analysis of data from these and the GOES satellites have become important instructional tools in schools throughout

the world.

9 See U.S. Congress, Office of Technology Assessment, OTA-ISC-239, International Cooperation and Competition in Ci\Di!ian Space

Acti}’ities (Washington, DC: U.S. Government Printing Office, 1985), ch. 3.

10 ks~en~ ctied by satellites or weather balloons that measure and transmit temperature, hufdity and press~e *ta.

11 me ~nutes of he ESA Mifi~t~ium of November, 1992, s~te:

(1) the Envisat-1 mission planned for launch in 1998, which will be mainly dedicated to understanding and monitoring the environment

and to providing radar data as a continuation of the data provided by ERS 2.

(2) the Metop-1 mission planned for launch in2000, which will provide operational meteorological observations to be carried out taking

into account the requirements expressed by the Eumetsat Council and in accordance with the terms of an Agreement to be concluded

with Eumetsat.
42 | Remote Sensing From Space

Box 3-E-DoD’s Defense Meteorological Satellite Program

Since the mid 1960s, the Defense Meteorological Satellite Program (DMSP) has provided military

commanders with accurate and up-to-date weather information. It began after DoD argued for a satellite to provide

reliable and unique weather data in support of U.S. troops involved in exercises or stationed in remote locations

that lack other sources of weather information.

Each current DMSP block 5D-2 satellite flies in a polar orbit at an altitude of 632 km (530 miles), and views

the entire globe twice per day. The satellites use optical and infrared sensors, which cover aground swath of just

under 3,000 km:

The Operational Linescan System (OLS), a visible and infrared imager that monitors aloud cover,

has three spectral bands. OLS operates at high spatial resolution (.6km) about 25 percent of the time.

TheMicrowave Imager(a radiometer used for determining soil moisture, precipitation, and ice cover)

has four channels, and a spatial resolution of 25-50 km.

The Microwave Temperature Sounder, used for vertical temperature sensing, has seven channels.

The Microwave Water Vapor Sounder, used for determining humidity through the atmosphere, has

five channels and spatial resolution between 40 and 120 km.

The satellites are capable of storing up to 2 days’ worth of data before downloading to ground stations located

at Fairchild AFB, Washington, and Kaena Point, Hawaii. There are currently two of the block 5D-2 satellites in

operation, and anew block upgrade is currently in development. The bus, the structural element of the satellite

that carries and powers the sensors, is similar to the bus used for the TIROS satellites.

Since 1975, the Navy, Air Force, and NOM have coordinated data processing efforts and exchanged

meteorological data through a shared processing network. Each of the processing centers has a particular

expertise: NOM for atmospheric soundings; Navy for sea surface measurements and altimetry; and Air Force for

visible and infrared mapped imagery and aloud imagery. The focus on each area of expertise is designed to limit

duplication and ensure cooperation. NOAA’s National Environmental Satellite, Data, and Information Service

archives the data processed by all three organizations.

SOURCE: U.S. Department of Defense, 1993.

2000. This will reduce U.S. costs of providing The program will include some moderate endata from the second polar orbiter, which is an

important first step in saving U.S. costs for the

entire polar satellite system. It may also enable

the United States and Europe to provide more

accurate coverage of weather and climate.

In the early part of the next century, Europe

plans to provide nearly half of the polar-orbiter

program. NOAA expects the cooperative polar

metsat program to lead to nearly identical U.S.

and European instruments, spacecraft, instrument

interfaces, standard communication procedures,

and data transmission standards. This is essential

to reduce problems of integrating instruments and

to assure that international partners can use each

other’s data with a minimum of complication.

hancement of instrument capabilities and the

addition of a TOMS to maintain the capability to

monitor atmospheric ozone.

This cooperative structure should enable the

United States and Europe to supply polar orbiter

data to the rest of the world. Eventually the two

partners might wish to embark on a broader

cooperative effort including other countries, which

would reduce U.S. and European costs and give

greater likelihood to a widely accepted international data standard. For example, Russia operates a polar-orbiting meteorological satellite,

Meteor-3, which already carries a TOMS instrument supplied by NOAA. Both the United States

and Russia would likely benefit from closer
Chapter 3-Weather and Climate Observations |43

cooperation on Earth observation satellite systems.

A more broadly based organization, including

for example, Russia, China, and India, could also

lead to a more capable system of polar orbiters. As

noted earlier, the United States and other spacefaring nations have organized the Committee on

Earth Observations from Space (CEOS) in order

to encourage development of complementary and

compatible Earth observation systems (and data),

and to address issues of common interest across

the spectrum of Earth observation satellite missions.12 Chapter 8, International Cooperation and

Competition, discusses these and other cooperative arrangements in more detail.

DEFENSE METEOROLOGICAL SATELLITE

PROGRAM

DoD maintains an independent meteorological

system, the Defense Meteorological Satellite

Program (DMSP), managed by the Air Force

Space Command (box 3-E). DMSP (figure 3-3)

uses a satellite platform very similar to the NOAA

POES platform and operates in near-polar orbit,

but carries somewhat different instruments. Among

other data, DMSP provides visible and infrared

ground images, measurements of soil and atmospheric temperature and moisture content, location

and intensity of aurora (for radar and communications), and measurements of sea state and wind

fields for naval operations. The military also uses

three-dimensional cloud data from DMSP in

computer models used in operational planning.

The phenomena observed by DMSP are similar to

those of interest to civilian weather forecasters,

but several of the data requirements, such as wind

speed at the oceans’ surface, are of crucial interest

to the military.

Figure 3-3-Artist’s Rendition of the Defense

Meteorological Satellite, DMSP Block 5D-2

DMSP, operated by the Air Force, gathers meteorological data

for military and civilian use. The military services and NOAA

operate a joint data center to coordinate data processing and

distribution.

SOURCE: U.S. Department of Defense.

Are two polar-orbiting satellite systems required? Critics of the policy of maintaining

separate polar-orbiting systems argue that the

United States cannot afford both systems.13 DoD

and NOAA counter that each satellite system

serves a unique mission. The NOAA satellites

routinely provide data to thousands of U.S. and

international users. DMSP serves a variety of

specialized military needs and provides valuable

microwave data to the civilian community. For

example, often the United States has troops

involved in exercises or stationed in remote

locations that would not have other sources of

weather information. DoD and NOAA regularly

exchange meteorological data. NOAA benefits

from DMSP data, and DoD also routinely uses

data from NOAA. Yet DoD’s needs for both

training and operations can be unique. DoD

12 Committm on Earth Observations Satellites, The Relet’ance of Satellite Missions to the Study of the Global Environment, ~CED

Conference, Rio de Janeiro, 1992, p 2.

13 ~ 1987 the Gener~ Accounting Office released a study arguing that the United States could achieve savings by eliminating duplication

of environmental satellite systems. See L1. S. Congress, General Accounlmg Office, NSIAD 87-107, ‘ ‘U.S. Weather Satellites: Achieving

Economies of Scale’ {Washington, DC: U.S. Government Printing Office, 1987).
44 | Remote Sensing From Space

requires a reliable source for global weather

forecasting, a function it argues is not duplicated

within NOAA. Military analysts fear that civilian

satellite systems, which are not under DoD

control, would be unable to deliver crucial

weather information to their users in time. DoD

also wants to have a domestic data source

insulated from international politics because data

from another country’s satellites might not always be made available. Finally, differences in

the priorities of instruments result in differing

replacement criteria for satellites when an instrument fails. For NOAA the sounder on its POES

has the greatest priority. The DMSP imager holds

the highest priority for the DoD. For these

reasons, DoD claims a distinct need for its own

meteorological system.

Congress may wish to revisit the question of

the possible consolidation of DMSP and the

NOAA polar orbiting system as it searches for

ways to reduce the Federal deficit. Such a study

should include a detailed analysis of the benefits

and drawbacks of consolidating civilian and

military sensor packages in one system, and the

ability of a combined system to serve military

needs in time of crisis. It should also look for

innovative ways for NOAA and DoD to continue

to work in partnership to carry out the missions of

both agencies.

NON-U.S. ENVIRONMENTAL

SATELLITE SYSTEMS

I ESA/Eumetsat Meteosat

The first European Meteosat satellite was

launched by ESA in 1977. Eumetsat took over

overall responsibility for the Meteosat system

from ESA in January 1987. The first spacecraft of

the Meteosat Operational Programme (MOP-1)

was launched in March 1989. MOP-3 is now

being prepared for launch in late 1993. It has a

7-year design life. ESA has developed the MOP

satellites on behalf of Eumetsat.

The Meteosat/MOP spacecraft design, instrumentation, and operation are similar to the current

U.S. NOAA GOES spacecraft. The spinstabilized spacecraft carry:

1.

2.

a visible-infrared radiometer to provide

high-quality day/night cloud cover data and

to collect radiance temperatures of the

Earth’s atmosphere; and

a meteorological data collection system to

disseminate image data to user stations, to

collect data from various Earth-based platforms and to relay data from polar-orbiting

satellites.

Meteosat spacecraft are in position to survey the

whole of Europe, as well as Africa, the Middle

East, and the Atlantic Ocean. They relay images

and data to a Meteosat Operations Control Centre

within ESA’S Space Operations Control Centre in

Darmstadt, Germany. A Meteorological Information Extraction Centre, located within the Meteosat control center, distributes the satellite data

to various users.

| Japanese Geostationary Meteorological

Satellite

The Japanese space agency, NASDA, developed the Geostationary Meteorological Satellites

1-4, which were launched in 1977, 1981, 1984,

and 1989. GMS-5 is projected for a 1995

launch.14 The GMS satellites are manufactured by

Hughes Space and Communications Group and

the Japanese corporation NEC, and draw heavily

on Hughes’ U.S. experiences with GOES. The

Japan Meteorological Agency operates the third

and fourth satellites, collecting data from the

systems’ radiometers (visible and infrared sensors), and space environment monitors.

14 GMS.S is Cmendy in storage at Hughes Space and Communications Group, awaiting an H-II launch vehicle, which is still under

development.
Chapter 3—Weather and Climate Observations |45

| Commonwealth of Independent States

The former Soviet Union assembled an integrated network of meteorological, land, and

ocean sensing systems that have served a wide

variety of military and civilian purposes. Now

essentially controlled by the Russian Republic,

these satellites represent one of the most capable

array of remote sensing systems deployed in the

world. The CIS operates eight different space

platforms (including the Mir space station) that

provide remotely sensed data.ls

The CIS Meteor environmental satellite system

consists of two or more polar orbiters, each of

which lasts only a relatively short time in orbit.

Each Meteor satellite provides data roughly

similar to the NOAA POES satellites. Meteor

satellites carry both visible-light and infrared

radiometers, and an instrument for monitoring the

flux of high energy radiation from space. Data

from these instruments lead to information about

the global distribution of clouds and snow and ice

cover, global radiation temperature of the surface,

cloud-top heights, and vertical distribution of

temperature. The data can be received around the

world by the same APT stations that receive data

from the U.S. polar orbiters.

15 See Nichol~ L. JohnsoL The Soviet Year in Space 1990 (Colorado Springs, CO: Teledyne Brow-n tigheem, 1991), PP. 59-70.
Surface

Remote

Sensing 4

B

alloons, aircraft, rockets, and spacecraft have all been

used successfully to acquire images and other data about

Earth’s surface. The earliest data were gathered more

than 100 years ago by photographic cameras mounted on

balloons. The advent of the airplane made possible aerial

photography and the accumulation of historic archives of

panchromatic (black and white) photographs to document

surface features and their changes. Eventually, experimenters

discovered that images acquired in several different regions of

the electromagnetic spectrum yielded additional valuable information about surface features, including likely mineral or oil and

gas-bearing deposits, or the health of crops. The Department of

Agriculture, for example, has routinely used infrared photography to monitor the extent of planted fields and the conditions of

crops, because, compared to many other surface features,

vegetation reflects infrared radiation strongly. Airborne microwave radar has demonstrated its utility for piercing clouds, and

for detecting the shape and condition of the soil beneath

vegetation.

The ability to transmit images of Earth via radio waves made

the use of satellites for remote sensing Earth practical. These

images, acquired by electro-optical sensors that convert light to

electronic signals,l can be transmitted to Earth as the satellite

passes over a ground station or they can be stored for later

broadcast. Placing remote sensing satellites in a near-polar orbit

at an altitude that allows them to pass over the equator at the same

I A video camera is one example of an instrument that employs an eledmoptica.1

sensor.

47
48 | Remote Sensing From Space

time each day makes it possible to collect images

of Earth’s surface with nearly the same viewing

conditions from day to day,2 enabling users of the

data easily to compare images acquired on

different days. Multispectral sensors enable users

to acquire data on surface spectral characteristics.

Other, non-polar orbits can be selected to maximize the accumulation of data over certain

latitudes. For example, scientists who designed

TOPEX/Poseidon, a scientific satellite designed

to collect topographic data on the oceans, chose

a mid-latitude orbit, optimizing the orbit to travel

above the world’s oceans, and allowing the

satellite to monitor the effects of tidal changes on

ocean topography.

THE LANDSAT PROGRAM

NASA initiated the Landsat program in the late

1960s as an experimental research program to

investigate the utility of acquiring multispectral,

moderate resolution data about Earth’s surface

(plate 4). Since then the Landsat system has

evolved into a technically successful system that

routinely supplies data of 30 meter (m) g-round

resolution in six spectral bands3 to users around

the world (box 4-A). A wide variety of government agencies at the local, State, and Federal

levels, academia, and industry make use of

Landsat data.

From a programmatic standpoint, however, the

Landsat program has proved much less successful

and has several times teetered on the brink of

extinction. As the experience of the past decade

has demonstrated, the utility of these data for

serving both public and private needs has made it

difficult to arrive at policies for support of

Landsat that satisfy all interests well. After an

8-year trial, Congress and other observers have

concluded that the experiment to commercialize the Landsat system has met with only

limited success.4

| Landsat 7

As noted earlier, continuity in the delivery of

remotely sensed data, in many cases, is critical to

their effective use. Many Landsat data users have

long warned that a loss of continuity in the

delivery of data from the Landsat satellites would

severely threaten their usefulness. Timely and

continuous data delivery are important for global

change research, but apply equally well to other

projects, including those designed to use Landsat

data for managing natural resources in regions

that lack other sources of data, or for urban

planning. Landsat data are extremely important

for detecting change in the conditions of forests,

range, and croplands over local, regional, and

global scales. They can also be used for monitoring changes in hydrologic patterns. Hence, continuity in the delivery of data from Landsat is an

important component of environmental research and monitoring.

In 1992, agreeing that maintenance of data

continuity was of crucial importance, members of

the House and Senate introduced legislation (H.R.

3614 and S. 2297) to establish a new land remote

sensing policy. The Land Remote Sensing Policy

Act of 19925 transfers control of Landsat from the

Department of Commerce to DoD and NASA, to

be managed jointly. According to the Administration Landsat Management Plan, DoD has

responsibility for procuring Landsat 7, planned

2 The sun’s angle with respect to the surface varies somewhat throughout the year, depending on the sun’s apparent position with respect

to the equator.

3 Band 6, the thermal band, senses data at a resolution of 120 meters.

4 See U.S. Congress, OffIce of Technology Assessment Remotely Sensed Data From Space: Dism”butz”on, Pn”cing, and Applications

(Washington DC: OffIce of Technology Assessment July 1992), pp. 34. U.S. House of Representatives, report to accompany H.R. 3614, the

Land Remote Sensing Policy Act of 1992, May 1992.

s H.R, 3614 WM pas5d by the House on June 9, 1992. After lengthy dehate, differences between the two bills were reSOkd h HR. 6613,

which was passed by the House in late September and by the Senate in early October. The Act was signed by President Bush on Oct. 29, 1992.
Chapter 4--Surface Remote Sensing |49

Box 4-A—The Landsat Program

The United States initiated the Landsat program in 1969 as a research activity. NASA launched Landsat 1

in 1972.1 Data from the Landsat system soon proved capable of serving a wide variety of government and private

sector needs for spatial information about the land surface and coastal areas. NASA designed, built, and operated

Landsats 1-3. The perceived potential economic value of Landsat imagery led the Carter administration to consider

commercial operation of the system and begin transferring control of Landsat operations and data distribution from

NASA to the private sector. The first step in the transition gave operational control of the Landsat system to NOAA

in 1981, because of NOAA’s extensive experience in operating remote sensing satellites for weather and climate

observations. Landsat 4 was launched in 1982; Landsat 52 became operational in 1984.3

In late 1983, the Reagan administration took steps to speed transfer operation of Landsat 4 and 5 to private

hands because it did not want to continue public funding for the system. A few proponents of commercialization

expected that industry could soon build a sufficient data market to support a land remote sensing system.4 Soon

thereafter, Congress began consideration of the Land Remote Sensing Commercialization Act of 1984, which was

intended to provide legislative authority for the transfer processs. Public Law 98-365 was signed into law on July

17, 1984. During deliberations over the Landsat Act, the administration issued a request for proposal (RFP) for

industry to operate Landsat and any follow-on satellite system. After competitive bidding,5 NOAA transferred

control of operations and marketing of data to EOSAT in 1985.6 At present, EOSAT operates Landsats 4 and 5

under contract to the Department of Commerce,7 and manages distribution and sales of data from Landsats 1-5.

EOSAT will operate Landsat 6, which is scheduled for launch in the summer of 1993. The U.S. Government has

paid for the Landsat 6 satellite and the launch. EOSAT will operate the satellite at its expense.

Because of concerns over continuity of data collection and delivery, Congress passed the Land Remote

Sensing Policy Act of 1992, which transfers control of the Landsat program from NOAA to DoD and NASA. This

legislation effectively ends the experiment to privatize the Landsat program. The two agencies will procure and

operate Landsat 7.

1 Initially ~i[ed the Earth Resources Technology Satellite, NASA retroactively changed its name in 1975.

2 Landsats 4 and 5 were designed by NASA and built by GE and Hughes Santa Barbara Research @nter.

3 see UCS. congress, congressional Research @rVice, me ~u~ufe Of ~~~ R@’note Sensing S~@//i~e SJ’SfWl

(Lax&t), 91-685 SPR (Washington, DC: The Library of Congress, Sept. 16, 1991) for a more complete account of the

institutional history of Landsat,

4 )-lowever, most analysts were extremely pessimistic about such prospects. See U.S. Congress, congressional

Budget Office, Encouraging Private ktvesrment in Space Activities (Washington, DC: U.S. Government Printing Office,

February 1991), oh. 3.

5 ~ven firms responded to the RFP, from which two were selected for further negotiation~OSAT and

Kodak/Fairchild. After a series of negotiations, during which the government changed the ground rules of the RFP, Kodak

dropped out, leaving EOSAT to negotiate with the Department of Commerce.

6 EOSATwas established as a joint venture by RCA (now part of Martin Marfetta Astrospace) and Hughes Spa@

and Communications Group (now part of General Motors) for this purpose.

7 Subsystems in both satellites have failed, but together they function as a nearfy complete satellite sYstem.

EOSAT has taken great care to nurse these two satellites along, in order to maintain ccmtinuity of data delivery until

Landsat 6 is operational.

SOURCE: U.S. Congress, Offica of Technology ksessment, Remotely Sensed Data from Space: Distribution, Pricing, and Applications

(Washington, DC: Office of Technology Assessment, July ?992), pp. 2-3.
50 | Remote Sensing From Space

Figure 4-1-Landsat 6 Satellite, Showing the Enhanced Thematic Mapper (ETM)

Enhanced

thematic ,

Orbit control

thrusters (4)

SOURCE: EOSAT, 1993.

for launch in late 1997. NASA will manage

operation of Landsat 7 and supervise data sales.6

The agencies will cooperate in developing specifications for possible future Landsat systems and in

developing new sensors and satellite technology.

Because data continuity is important to many

users, program managers specified that Landsat 7

should at a minimum duplicate the format and

other characteristics of data from Landsat 6.

Landsat 7 will therefore carry an Enhanced

Thematic Mapper (ETM) sensor very similar to

the one on Landsat 6 (figure 4- 1). NASA and DoD

are currently designing an additional sensor for

Landsat, called the High Resolution Multispectral

Stereo Imager (HRMSI), If funded, HRMSI

would greatly improve the ability of Landsat 7 to

gather data about Earth’s surface. As currently

envisioned, HRMSI would have much higher

surface resolution than the ETM (5 m black and

white; 10 m in four visible and infrared bands),

and would be capable of acquiring stereo images.7

Combined, these capabilities would allow the

Defense Mapping Agency and the U.S. Geological Survey, among others, to use Landsat data in

creating multispectral topographic maps. In addition, HRMSI would have the ability to acquire

data on either side of its surface track, allowing

the instrument to improve its revisit time from

Landsat’s current 16 days to only 3 days. This

capability would markedly increase the utility of

Landsat data for a variety of applications, such as

detection of military targets and agricultural

monitoring, where timeliness is an important

factor. If Congress wishes to improve the

ability of U.S. agencies to use remotely sensed

data in carrying out their legislatively mandated missions, it may wish to fund HRMSI or

a sensor with similar capabilities.

b A Comercial entity may well be chosen to market Landsat data.

7 Stereo images make possible the creation cf topographic maps.
Chapter 4-Surface Remote Sensing |51

NASA and DoD estimate that procuring and

operating Landsat 7 with only the ETM sensor

through the end of its planned 5-year lifetime will

cost about $880 million (in 1992 dollars )--$4lO

from NASA and $470 from DoD, About $398

million will be needed in the first few years to

purchase the satellite with the ETM. An additional $403 million will be needed between 1994

and the projected end of Landsat 7’s useful life to

purchase the HRMSI, enhance the ground system

to handle the increased data flow,8 and operate the

satellite. General Electric Corp. and Hughes

Santa Barbara Research Center, which built

Landsat 6 (table 4-l), were awarded the contract

to build Landsat 7 (table 4-2).9

| Future Landsat Satellites

Planning for a system to replace Landsat 7 after

it lives out its useful life is in the very early stages.

Higher spatial resolution, a greater number of

spectral bands, and improved sensor calibration are among the most important improvements sought for future Landsat satellites.

However, timeliness of data delivery after data

acquisition and the revisit time of the satellite l0 ”

also need improvement, especially for monitoring short-term changes such as occur in

crop and other renewable resource production.

If Landsat 7 proceeds as planned, scientists

will be able to experiment with the use of

high-resolution, stereo images in evaluating ecological change. However, the limited number of

spectral bands provided by Landsat 7 may inhibit

detailed ecological modeling of land processes.

Given the importance of remotely sensed land

Table 4-l—Technical Characteristics of Landsat 6

Orbit and coverage:

LandSat 6 will follow an orbit similar to that of Landsats 4

and 5:

Orbit Altitude: 705 kilometers

Type: Circular, sun synchronous, one orbit every 98.9 minutes

(about 14.5 per day)

Equatorial crossing time: 9:45 am

Repeat coverage at Equator 16 days

Inclination: 98.21

Sensor package:

Landsat 6 will carry a Thematic Mapper Sensor similar to

Landsats 4 and 5, but with improved calibration, and an

additional, higher resolution black and white (panchromatic)

band.

Enhanced Thematic Mapper characteristics:

● Panchromatic band, 15 meter ground resolution

● Six (visible-infrared) multispectral bands, 30 meters

resolution

● One thermal infrared band, 120 meters.

SOURCE: Earth Observation Satellite Co., 1992.

data to global change research (see chs. 5 and 6),

NASA may wish to consider the potential for

incorporating some of the enhanced spectral

capabilities of the proposed High Resolution

Imaging Spectrometer (HIRIS)ll into the design

for a follow-on to Landsat 7. HIRIS designers

have dealt with many of the design and operational issues associated with hyperspectral capabilities and could significantly improve the design of a successor to Landsat 7.

Recent technological developments, in, for

example, focal plane technology and active cryocoolers, suggest that it may be possible to design,

build, and operate a Landsat 8 that would be much

more capable than Land sat 7. The Land Remote

Sensing Policy Act of 1992 calls for a technology

development program to fund new sensors and

g With the HRMSI sensor, Landsat 7 would have a maximum data transfer rate from the satellite to the ground station of about 300

megabytes per second.

s Martin Marietta Astrospace, which recently purchased GE Astrospace, is now the prime contractor. Hughes Santa Barbara Research Center

built the ETM for Landsat 6, will construct the ETM for Landsat 7. It would also develop HRMSI for Landsat 7. Although several aerospace

corporations expressed interes~ this tarn was the only bidder, in part because other companies felt they would not be competitive with the team

that had built Landsat 6.

10 per~ps by doubling the number of satellites in orbit.

11 A high.r~~olution sensor that had been proposal for the EOS program, but recently CMICekd. see ch. 5: G~Ob~ ~ge Res~ch.
52 | Remote Sensing From Space

Table 4-2—Technical Characteristics of Landsat 7

Compared to Landsat 6, Landsat 7 will have:

1. Improved spatial resolution-a new sensor with 5 meters

resolution in the panchromatic band and 10 meters in 4

visible and near infrared bands.

2. lmproved Absolute Radiometric Calibration-An Enhanced

Thematic Mapper Plus will have improved calibration of the

sensor to allow for gathering improved science data and

improved long-term radiometric stability of the sensors.

3. Stereo mapping capability~The 5 meter sensor will collect

4,

5.

6.

stereo image pairs along the satellite track with a ground

sample distance of 5 meters and a vertical relative accuracy

of 13 meters.

Cross-track pointing-The contractor team will provide the

ability to point to locations on either side of the satellite’s

ground track in order to revisit areas imaged on earlier

passes. With a 16-day revisit time, Landsats 4,5, and 6 are

not able to provide timely data on surface changes that

occur in time periods less than 16 days, such as during

critical growing periods in the spring.

/mproved radiormetric sensitivity~lmprovements in the range

of light intensity over which the Landsat sensors can

accurately sense reflected or emitted light.

/reproved satellite position accuracy-Mapping applications will be much improved by knowing more accurately the

spacecraft’s position and attitude in orbit at all times.

Landsat 7 will carry a GPS receiver to enable improved

position data.

SOURCE: National Aeronautics and Space Administration, 1993.

spacecraft for future land remote sensing satellites.12 New technologies introduce a significant element of technological and cost risk. If

Congress wishes to reduce these risks for a

future Landsat system, Congress could provide DoD and NASA sufficient funds to support a technology development and testing

program for advanced Landsat technology.

Satellite and sensor designers have suggested a number of improvements for land remote

sensing satellites, including some focused on

reducing satellite size and weight. However,

proving new concepts will require extensive

design review and technology development. In

addition, constructing a satellite system that is

expected to last 5 or more years without significant degradation requires extensive testing at

both the component and system level.

Developing new sensors for programs that

have requirements for returning data on a long

term, operational basis presents a special challenge to spacecraft designers because these instruments must meet more stringent specifications than those for short-term research missions.

Hence, progress in sensor and spacecraft design

tends to be incremental, rather than revolutionary.

Satellite system experts estimate that the development of a new satellite system for Landsat 8,

beginning with concept development and proceeding through detailed design and construction, could take as long as 8 years. Hence, if

Congress wants to increase the chances of

maintaining continuity of Landsat data delivery after Landsat 7, it should direct DoD and

NASA to start planning in 1993 to specify the

design of Landsat 8.

NON-US. LAND REMOTE SENSING

SYSTEMS

Other countries have developed and flown very

capable land remote sensing satellites.13 The

following section summarizes the capabilities of

these systems.

| France

SYSTEME POUR D’OBSERVATION DE LA TERRE

(SPOT)

The SPOT-2 satellite, which was designed,

built, and is operated by Centre Nationale

d’Etudes Spatial (CNES), is the second in a series

of SPOT satellites. It achieves a higher spatial

resolution than Landsat 6, but has fewer spectral

bands. It is capable of acquiring panchromatic

data of 10 m resolution, and 20 m resolution data

in 3 spectral bands. SPOT’s off-nadir viewing

yields stereoscopic pairs of images of a given area

12 ~blic bW 102-555, Title III; 106 STAT. 4174; 15 USC 5631-33.

13 SW app. D for more detail on these systems.
Chapter 4-Surface Remote Sensing |53

by making successive satellite passes. A standard

SPOT scene covers an area 60 x 60 kilometers

(km). CNES expects to launch SPOT 3 in late

1993.

CNES developed SPOT with the intention of

selling data commercially and attempting to

develop a self-sustaining enterprise. SPOT Image,

S. A., the French company formed to market

SPOT data to a global market, is a major

competitor to EOSAT in selling remotely sensed

land data. Although SPOT Image has been

successful in increasing its yearly sales each year,

and now makes a modest profit on SPOT operations, it still does not earn sufficient income to

support the construction and launch of replacement satellites. The French Government, through

CNES, is expected to continue to provide additional satellites through the end of the decade.

During the 1992 and 1993 growing seasons,

CNES reactivated SPOT-1 in order to provide

more timely coverage of agricultural conditions.

Key to the French strategy in building a market

for remote sensing data is the CNES plan to assure

continuity of data delivery and a series of

evolutionary upgrades to the SPOT system. By

the end of the century, CNES plans to add the

capability of gathering 5 m resolution, panchromatic stereo data. It also plans to add an

infrared band to enhance the data’s usefulness in

agriculture and other applications. The new data

policy for Landsat 7 under which “unenhanced

data are available to all users at the cost of

fulfilling user requests’ 14 may pose a problem for

SPOT Image, as Landsat data would be sold to

private sector users for much less than the current

prices. OTA will examine these and other data

issues in a future report on remotely sensed data.

continuous coverage of the country. An indigenous ground system network handles data reception, data processing, and data dissemination.

India’s National Natural Resources Management

System (NNRMS) uses IRS data to support a

large number of applications projects.

India has orbited two IRS satellites: IRS-1A

was launched in March 1988 by a Russian

booster; IRS-lB reached space in August 1991,

also launched by a Russian vehicle. Each carries

two payloads employing Linear Imaging Selfscanning Sensors (LISS). The IRS-series have a

22-day repeat cycle, The LISS-I imaging sensor

system consists of a camera operating in four

spectral bands, compatible with the output from

Landsat-series Thematic Mapper and SPOT HRV

instruments. The LISS-IIA & B is comprised of

two cameras operating in visible and near infrared

wavelengths with a ground resolution of 36.5 m,

and swath width of 74.25 km.

As part of the National Remote Sensing

Agency’s international services, IRS data are

available to all countries within the coverage zone

of the Indian ground station located at Hyderabad.

These countries can purchase the raw/processed

data directly from NRSA Data Centre.

India is designing second generation IRS-lC

and ID satellites that will incorporate sensors

with resolutions of about 20 m in multispectral

bands and better than 10 m in the panchromatic

band. System designers intend to include a

short-wave infrared band with spatial resolution

of 70 m. The system will also include a Wide

Field Sensor (WiFS) with 180 m spatial resolution and larger swath of about 770 km for

monitoring vegetation.

| Japan

| India

INDIAN REMOTE SENSING SATELLITE (IRS)

As India’s first domestic dedicated Earth resources satellite program, the IRS-series provides

JAPAN EARTH RESOURCES SATELLITE (JERS-1)

A joint project of the Science and Technology

Agency, NASDA, and the Ministry of International Trade and Industry (MITT), JERS-1 was

14 ~blic IAw lo2-5.5; 106 STAT 4170; 15 USC .5615.
54 | Remote Sensing From Space

launched by a Japanese H-1 rocket in February

1992. Observations from JERS-1 focus on land

use, agriculture, forestry, fishery, environmental

preservation, disaster prevention, and coastal

zone monitoring. It carries a synthetic aperture

radar and an optical multispectral radiometer.

JERS-1 data are received at NASDA’S Earth

Observation Center, Saitama, and at the University in Kumamoto Prefecture, the Showa Base in

the Antarctica, and the Thailand Marine Observation Satellite station. Under a NASDA-NASA

Memorandum of Understanding, the NASAfunded SAR station in Fairbanks, Alaska, also

receives JERS-1 data. These data overlap the

SAR data from the European ERS-1 mission, and

the future Canadian Radarsat mission, planned for

launch in 1994.

Japan also operates the Marine Observation

Satellite (MOS lb) system that collects data about

the land as well as the ocean surface. See below

for description.

| Russia

RESURS-O

The Resurs-O digital Earth resources satellites

are roughly comparable to the U.S. Landsat

system and are derived from the Meteor series of

polar orbiters. They carry multiple multispectral

instruments operating in the visible to thermal

infrared. Remote sensing instruments aboard a

Resurs-O comprise two 3-band scanners, providing 45 m resolution. A second 5-band scanner

senses a 600 km swath at 240 m X 170 m

resolution. A 4-band microwave radiometer views

a 1,200 km swath at 17 to 90 km resolution. In

addition a side-looking synthetic aperture radar

provides 100 km coverage at 200 m resolution.

The Resurs-O spacecraft can process some data in

orbit and relay data directly to ground stations.

Russian scientists are planning a follow-on to

this series, which would carry high-resolution

optical sensors capable of 15 to 20 m resolution.

They have explored the possibility of establishing

commercial Resurs-O receiving stations in Sweden, as well as the United Kingdom.

RESURS-F

This class of photographic satellite mimics

Russian military reconnaissance spacecraft by

using a film return capsule, which is deorbited

and brought to Earth under parachute. Resurs-Fl

and Resurs-F2 spacecraft use the Vostok reentry

sphere, earlier used for launching cosmonauts.

The Resurs-Fl typically flies at 250km to 400km

altitude for a 2-week period and carries a threechannel multispectral system that includes three

KATE-200 cameras and two KFA-1OOO cameras.

The KATE--200 camera provides for Earth survey

in three spectral bands. It can collect stereoscopic

imagery having an along-track overlap of 20, 60,

or 80 percent.15 Resolution of the images, according to spectral band and survey altitude, varies

from 10 to 30 m over a 180 km swath width. The

KFA-1OOO cameras provide stereo images of up

to 5 m resolution with a 60 km swath width.

The Resurs-F2 spacecraft normally circuit

Earth for as long as 3 to 4 weeks in a variable orbit

of 259 to 277 km. Onboard is the MK-4 camera

system, which can survey the Earth using a set of

four cameras in six spectral channels. Also, 5 to

8 m resolution stereo is possible with a swath

width of 120 to 270 km. Imagery provided by

Resurs-Fl and F2 spacecraft are being offered

commercially through Sojuzkarta.

OCEAN SENSING AND THE ICE CAPS

Because the oceans cover about 70 percent of

Earth’s surface, they make a significant contribution to Earth’s weather and climate. The oceans

interact constantly with the atmosphere above

them and the land and ice that bound them. Yet

scientists know far too little about the details of

the oceans’ effects on weather and climate, in part

because the oceans are monitored only coarsely

by ships and buoys. Improving the safety of

15 Refi~le s(er~ r~uires at least 60 percent overlap.
Chapter 4-Surface Remote Sensing |55

people at sea and managing the seas’ vast natural

resources also depend on receiving better and

more timely data on ocean phenomena, Satellite

remote sensing is one of the principal means of

gathering data about the oceans.

| Research on Ocean Phenomena

In order to understand the behavior of the

oceans and to make more accurate predictions of

their future behavior, scientists need to gather

data about sea temperature, surface color, wave

height, the distribution of wave patterns, surface

winds, surface topography, and currents. Fluctuations in ocean temperatures and currents lead to

fluctuations in the atmosphere and therefore play

a major part in determining weather and climate.

For example, El Nino, the midwinter appearance

of warm water off the coast of South America

every 4 to 10 years, decreases the nutrients in the

coastal waters off South America, and therefore

the number of fish. However, in 1988, El Nino

had a major effect on weather patterns over North

America. The warm water was pushed further

north than usual, which created severe storms

hundreds of miles to the north and shifted the jet

stream further north. This blocked the Canadian

storm systems, which normally send cool air and

moisture south during the summer, and led to an

unusual amount of dry, hot weather, precipitating

severe drought in the central and eastern United

States. l6 The drought, in turn, severely affected

U.S. agriculture. The winter 1992-1993 El Nino

condition had a major role in producing extremely

high levels of rain and snow in the western United

States during February 1993. Understanding and

predicting these interactions are major goals of

climatologists.

The study of other ocean phenomena would

enhance scientists’ understanding of the structure

and dynamics of the ocean. For example, observations of wave conditions are important for modeling ocean dynamics. Because winds create waves,

measurements of wind speed and direction over

wide areas can lead to estimates of wave height

and condition.

Closely observing the color of the ocean

surface provides a powerful means of determining

ocean productivity. Variations in ocean color are

determined primarily by variations in the concentrations of algae and phytoplankton, which are the

basis of the marine food chain. Because these

microscopic plants absorb blue and red light more

readily than green light, regions of high phytoplankton concentration appear greener than those

with low concentration. Because fish feed on the

photoplankton, regions of high concentration

indicate the possibility of greater fish population.

Interest in using satellites to measure ocean

phenomena began in the 1960s. In 1978, the

polar-orbiting TIROS satellites began to gather

data on sea surface temperatures using the AVHRR

(plate 5) and microwave sensors. The maps of sea

surface temperatures produced form these data

demonstrate complex surface temperature patterns that have led to considerable speculation

about the physical processes that might cause

such patterns. However, it was not until NASA

launched Nimbus 7 and Seasat in 1978 that

scientists were able to gather comprehensive

measurements of the oceans. Nimbus-7 carried a

Scanning Multichannel Microwave Radiometer

(SMMR) that provided accurate measurements of

sea surface temperatures. By measuring the color

of the ocean surface, its Coastal Zone Color

Seamer (CZCS) provided estimates of ocean

biological productivity.

Seasat 17 carried five major instruments-an

altimeter, a microwave radiometer, a scatterometer, a visible and infrared radiometer, and a

synthetic aperture radar. Scientists used data from

these instruments to measure the amplitude and

direction of surface winds, absolute and relative

16 D. JiUIRS Baker, Planer Earth: The Viewfrom Space (Cambridge, MA: Hanfard UD.iversity ~ess, 1990), pp. 2-3.

IT U.S. ConWws, Mice of Technology Assessment Technology and Oceanography, OTA-O-141 (Washington+ D. C.: U.S. Gve-ent

Printing ~lC43, 1981).
56 | Remote Sensing From Space

surface temperature, the status of ocean features

such as islands, shoals, and currents, and the

extent and structure of sea ice. Although Seasat

operated only 3 months, it returned data of

considerable value to ocean scientists and paved

the way for the current generation of U.S. and

foreign ocean instruments and satellite systems.

| Operational Uses of Ocean Satellites

The development and operation of Seasat

demonstrated the utility of continuous ocean

observations, not only for scientific use, but also

for those concerned with navigating the world’s

oceans and exploiting ocean resources. Its success convinced many that an operational ocean

remote sensing satellite would provide significant

benefits.18 The SAR,19 the scatterometer, and the

altimeter all gathered data of considerable utility.

Not only do DoD and NOAA have applications

for these sensors in an operational mode (i.e.,

where continuity of data over time is assured and

the data formats change only slowly), but so also

do private shipping firms and operators of ocean

platforms. Knowledge of currents, wind speeds,

wave heights, and general wave conditions at a

variety of ocean locations is crucial for enhancing

the safety of ships at sea, and for ocean platforms.

Such data could also decrease costs by allowing

ship owners to predict the shortest, safest sea

routes.

Over the past decade, the U.S. Government has

made two major attempts to develop and fly a

dedicated operational ocean satellite carrying

sensors similar to those on Seasat. Both attempts

failed when the programs were canceled for lack

of funding. In 1982, the United States canceled a

joint DoD/NOAA/NASA program to develop the

National Oceanic Satellite System (NOSS), and

in 1988 it canceled a similar satellite that the

Navy was attempting to develop, the Navy

Remote Ocean Sensing Satellite (N-ROSS). TOPEX/

Poseidon, a research satellite, was launched in

1992 for altimetry studies.

Data from the SeaWiFS instrument aboard the

privately developed SeaStar satellite, will provide

ocean color information, which could have considerable operational use.20Although NASA’s

EOS will include ocean sensors to support

research on issues concerning the oceans and

ocean-atmospheric interactions, no instruments

devoted to operational uses are planned.

| Observations of Sea Ice

Because sea ice covers about 13 percent of the

world’s oceans, it has a marked effect on weather

and climate. Thus, measurements of its thickness,

extent, and composition help scientists understand and predict changes in weather and climate.

Until satellite measurements were available, the

difficulties of tracking these characteristics were

a major impediment to understanding the behavior of sea ice, especially its seasonal and yearly

variations.

The AVHRR visible and infrared sensors

aboard the NOAA POES have been used to

follow the large-scale variations in the Arctic and

Antarctic ice packs. Because they can “see

through” clouds, synthetic aperture radar instruments are particularly useful in tracking the

development and movement of ice packs, which

pose threats to shipping, and in finding routes

through the ice. Data from ERS-1, Almaz, and

JERS-1 (see below) have all been studied to

understand their potential for understanding sea

ice and its changes. The Canadian Radarsat will

be devoted in part to gathering data on the ice

la Dodd Montgome~, “CommercialApplications of Satellite Oceanography,” Oceanus24, No. 3, 1981; Joint Oceanographic Institutions,

“Oceanography From Space: A Research Strategy for the Decade 1985 -1995,” report (Washington, DC: Joint Oceanographic Institutions,

1984).

19 S= ~Wn& B, box B-3, for a description of how synthetic apatu.re molar OperateS.

m See below for a ~description of SeaStar. See ch. 7 for discussion of the financial arrangements that have made its development

possible.
Chapter 4-Surface Remote Sensing |57

packs to aid shippers, fishing fleets, and other

users of the northern oceans. NASA is providing

a receiving station in Alaska to collect Radarsat

data and make them available to U.S. researchers.

MAJOR EXISTING OR PLANNED OCEAN

AND ICE REMOTE SENSING SATELLITES

The separation of satellites into those that view

the land or the ocean is highly artificial because

instruments used for land features often reveal

information about the oceans and vice versa. In

addition, because most instruments specifically

designed either for land or ocean features can fly

on the same satellite, such separations are not

required for operational use, Nevertheless, as a

result of the division of disciplines and the desire

of funding agencies to group instruments designed primarily for investigating land or ocean

features on the same satellite bus, satellites

generally fall into one category or the other.

| Canada

RADARSAT

This satellite, to be launched in 1995 aboard a

Delta II launcher, will carry a C-band synthetic

aperture radar capable of operating in several

different modes and achieving resolutions from

10 to 50 m, depending on the swath width desired.

It is designed to gather data for:

1.

2.

3.

4.

5.

6.

7.

ice mapping and ship navigation;

resource exploration and management;

high arctic surveillance;

geological exploration;

monitoring of crop type and health;

forestry management;

Antarctic ice mapping.

The satellite will have a repeat cycle of 1 day

in the high Arctic, 3 days over Canada, and 24

days over the equatorial regions. The Canadian

firm, Radarsat International, will market data

collected from the Radarsat system. It will offer

contracts to stations around the world that are

collecting SPOT and/or Landsat data, enabling

them to collect and market Radarsat data.

| European Space Agency

EARTH RESOURCES SATELLITE (ERS-1)

The ERS-1 satellite was launched into polar

orbit by an Ariane booster in July 1991 and was

declared operational 6 months later. Operating

from a Sun-synchronous, near-polar orbit, ERS-1

is the largest and most complex of ESA’S Earth

observation satellites. It carries several instruments:

1.

2.

3.

4.

Along Track Scanning Radiometer and

Microwave Sounder, which makes infrared

measurements to determine, among other

parameters, sea surface temperature, cloud

top temperature, sea state, and total water

content of the atmosphere.

Radar Altimeter, which can function in one

of two modes (ocean or ice) and provides

data on significant wave height; surface

wind speed; sea surface elevation, which

relates to ocean currents, the surface geoid

and tides; and various parameters over sea

ice and ice sheets.

Synthetic Aperture radar to study the relationships between the oceans, ice, land, and the

atmosphere. The SAR’S all-weather, day-andnight sensing abilities is critical for polar

areas that are frequently obscured by

clouds, fog, and long periods of darkness.

Wind Scatterometer to measure surface

winds. By measuring the radar backscatter

from the same sea surface, picked up by the

three antennas placed at different angles,

wind speed and direction can be determined.

The primary objectives of the ERS-1 mission

focus on improving understanding of oceans/

atmosphere interactions in climatic models; advancing the knowledge of ocean circulation and

transfer of energy; providing more reliable estimates of the mass balance of the Arctic and
58 I Remote Sensing From Space

Antarctic ice sheets; enhancing the monitoring of

pollution and dynamic coastal processes (plate 6);

and improving the detection and management of

land use change.

More specifically, data form ERS-1 are being

used to study ocean circulation, global wind/wave

relationships; monitor ice and iceberg distribution; determine more accurately the ocean geoid;

assist in short and medium-term weather forecasting, including the determination of wind speed

and direction, as well as help locate pelagic fish

by monitoring ocean temperature fronts. Data

from the spacecraft also contribute to the international World Climate Research Program and to

the World Ocean Circulation Experiment.

| Japan

MARINE OBSERVATION SATELLITE (MOS)

The MOS-1 was Japan’s first Earth observation

satellite developed domestically. The frost MOS1 was launched in February 1987 from Tanegashima Space Center by an N-II rocket. Its

successor, MOS - lb, with the same performance

as MOS-1, was launched by an H-I rocket in

February 1990. These spacecraft orbit in sunsynchronous orbits of approximately 909 km and

have a 17-day recurrent period, circling the Earth

approximately 14 times a day. The two spacecraft

can be operated in a simultaneous and/or independent mode.

MOS-1 and MOS-lb are dedicated to the

following objectives:

establishment of fundamental technology for

Earth observation satellites;

experimental observation of the Earth, in

particular the oceans, monitoring water turbidity of coastal areas, red tide, ice distribution; development of observation sensors;

verification of their functions and performance; and

. basic experiments using the MOS data

collection system.

Each of the spacecraft carry three sensors: a

Multispectral Electronic Self-seaming Radiometer (MESSR); a Visible and Thermal Infrared

Radiometer (VTIR); and a Microwave Scanning

Radiometer (MSR). MOS products are available

for a fee from the Remote Sensing Technology

Center of Japan (RESTEC).

| U.S./French

TOPEX/POSEIDON

TOPEX/Poseidon is a research satellite devoted primarily to highly accurate measurements

(to an accuracy of about 2 cm) of the height of the

oceans. The satellite, which was launched in

September 1992 by the European Ariane launcher,

also carries a microwave radiometer in order to

correct for the effects of water vapor in the

atmosphere. France supplied a solid-state altimeter and a radiometric tracking system. The satellite’s orbit allows determination of ocean topography from latitudes 63° north to 63° south. The

height of the ocean is crucial to understanding

patterns of ocean circulation. Accurate altitude

measurements could lead to better understanding

of ocean topography and dynamics, tides, sea ice

position, climate, and seafloor topography, among

other ocean-related qualities.21 Data from TOPEX/

Poseidon are distributed to scientists in the United

States, France, and other countries in accordance

with data policies agreed on between NASA,

CNES and other members of CEOS.

| Orbital Sciences Corp.

SEASTAR/SEAWlFS

The Orbital Sciences Corp. (OSC) is constructing the SeaStar satellite, which will carry the

Sea-viewing Wide Field of view Sensor

(SeaWiFS), an 8-band multispectral imager operZI “Sate~te ~~e~c M~~men~ of tie Oceaw” re~rt of the TOPEX Science Working OrOUp, NASA, JPL 1981; Richd FKleld,

“The Shape of Earth from Space, ” New Scientist, Nov. 15, 1984, pp. 4650.
Chapter 4-Surface Remote Sensing |59

Figure 4-2—The Orbital Sciences Corporation’s SeaStar Ocean Color Satellite System

and

es

~ Commercia l

users

ating in the very near infrared portion of the

spectrum. z2 SeaWiFS, which OSC plans to

launch in late 1993, will be used to observe

chlorophyll, dissolved organic matter, and pigment concentrations in the ocean. The sensor will

contribute to monitoring and understanding the

health of the ocean and concentration of life forms

in the ocean. Data will have significant commercial potential for fishing, ship routing, and aquaculture, and will be important for understanding

the effects of changing ocean content and temperatures on the health of aquatic plants and animals.

Under an experimental arrangement with NASA,

the company’s SeaStar satellite will collect ocean

color data for primary users (including NASA),

who then have the option to sell both unenhanced

and enhanced data to other users (figure 4-2).

NASA has agreed to purchase data from orbital

Sciences in a so-called anchor tenant arrangement

in which NASA has paid OSC $43.5 million up

front. This arrangement allowed OSC to seek

private financing for design and construction of

the satellite.23

This experimental data purchase agreement

should provide valuable lessons for possible

future agreements of a similar character. If it is

successful, the Federal Government may purchase quantities of other remotely sensed data

from private systems, allowing these firms to earn

a profit marketing data to other users.

22 B~lt by Hughes Santa Barbara Research Center.

23 See ch. 7: The p~”vate Sector, for a more detailed discussion of this arrangement.
60 | Remote Sensing From Space

Box 4-B-System Tradeoffs

Remote sensing instrumentation can be launched into space in a variety of orbital altitudes and inclinations;

instruments can be flown on endo-atmospheric systems-aircraft, balloon, and remotely piloted aircraft; or they

can be sited on the ground. The selection of a particular “system architecture” for a given mission typically involves

many compromises and tradeoffs among both platforms and sensors. For imaging missions based on satellites,

the most important factors indetermining overall system architecture include the required geographical coverage,

ground resolution, and sampling time-intervals. These affect platform altitude, numbers of platforms, and a host

of sensor design parameters. Each remote sensing mission will have unique requirements for spatial, spectral,

radiometric, and temporal resolution. A number of practical considerations also arise, including system

development costs; the technical maturity of a particular design; and power, weight volume, and data rate

requirements.

Spectral resolution refers to the capability of a sensor to categorize electromagnetic signals by their

wavelength. Radiometric resolution refers to the accuracy with which the intensities of these signals can be

recorded. Finally, ternporal resolution refers to the frequency with which remote sensed data are acquired. it is

also possible to categorize the “coverage” of three of the instruments’ four resolutions: spatial coverage is a

function of sensor field of view; spectral coverage refers to the minimum and maximum wavelengths that can be

sensed; and radiometric coverage refers to the range of intensities that can be categorized. The required

measurement intervals vary widely with mission. For example, data on wind conditions might be required on time

scales of minutes; data on crop growth might be needed on time scales of a week or more; and data on changes

in land use are needed on time scales of a year or more.

Sensor design requires tradeoffs among the four “resolutions” because each can be improved only at the

expense of another. Practical considerations also force tradeoffs; for example, on Landsat, multispectral and

spatial data compete for on-board storage space and fixed bandwidth data communication channels to ground

stations. For a given swath width, the required data rate is inversely proportional to the square of the spatial

resolution and directly proportional to the number of spectral bands and the swath width. For example, improving

the resolution of Landsat from 30 m to 5 m would raise the data rate by a factor of 36. Adding more bands to Landsat

would also increase the required data rate. Changing the width of coverage can increase or decrease the required

data rate proportional to the change in swath width. The baseline design for a proposed high-resolution imaging

spectrometer (HIRIS) sensor would have 192 contiguous narrow spectral bands and a spatial resolution of 30 m.1

To accommodate these requirements, designers chose to limit the ground coverage and thereby reduce the swath

width of the sensor. HIRIS would have been used as a “targeting” instrument and would not acquire data

continuously.

Spatial resolution drives the data rate because of its inverse square scaling. One way to reduce the data rate

requirements without sacrificing spatial resolution is to reduce the field of view of the sensor.2 Designing

multispectral sensors that allow ground controllers to select a limited subset of visible and infrared bands from a

larger number of available bands is another option to lower data rates?

1 HIRIS was eliminated as an EOS instrument during the restructuring of EOS (see ch. 5: @Obai mange

Research).

2 ~edifferentre~utio~ can betradedagainstgroundcoverage. Forexampie, the French SPOTsateiiiteoffers

10 m resolution in black and white, but its ground swath width is 60 km versus Landsat 5’s 185 km.

3 Datacornpr~on isanotheroption toreducedata rates. Aiossiesscompression wouid alkwthefuiisetofmw

data to be reoovered; reductions in data rates of approxhnateiy a factor of two might bs gained implementing these

algorithms. Most researchers prefer this to a data set that has been preprooeasd in away that destroys some data (but

reduces data rate requirements) because “one person’s ndse can prove to be another person’s signai.”

SOURCE: 19S3 Landsat Short Oourse, University of California 8anta 8arbaraand Hughes SBRC;Ofiice of Tectmoiogy Assesemen$ 1993.
Chapter 4-Surface Remote Sensing | 6 1

| United States

GEODESY SATELLITE (GEOSAT)

Launched in 1985, this satellite carried an

improved version of the altimeter that flew on

Seasat. Designed by the U.S. Navy primarily for

collecting precise measurements of ocean topography for military use, the satellite was initially

placed into a 108° orbit. The data from this part of

the mission were classified but have recently been

released for scientific use. The satellite was later

maneuvered into a different orbit in order to

collect data that would allow oceanographers to

determine changes in ocean topography. Geosat

operated until 1989. The Navy plans to replace it

with Geosat Follow On (GFO), which would fly

in an orbit that is 1800 out of phase with the orbit

of Geosat, Current plans call for a 1995 launch of

GFO.

| Russia

ALMAZ

From March 1991 until November 1992, Alrnaz1, a large spacecraft equipped with synthetic

aperture radar (SAR), provided radar images of

the oceans and Earth’s surface.24 Almaz (Russian

meaning “diamond”) orbited Earth in a 300

km-high orbit, providing coverage of designated

regions at intervals of 1 to 3 days. Imagery was

recorded by onboard tape recorders, then transmitted in digital form to a relay satellite that, in

turn, transmitted the data to a Moscow-based

receiving facility. The imagery formed a hologram recorded on high-density tape for later

processing as a photograph. Alternatively, a

digital tape can be processed. Hughes STX Corp.

of Lanham, Maryland, is the exclusive worldwide

commercial marketer, distributor, processor, and

licenser of data from the Almaz-1 spacecraft.25 A

second Almaz satellite is available for launch if

the funds can be found to launch and operate it.

Although the cost of such an operation is reported

to be extremely low compared to other SAR

satellites, NPO Machinostroyenia, the satellite

builder, has not yet found an investor.

| Sensor Design and Selection

Each remote sensing mission has unique requirements for spatial, spectral, radiometric, and

temporal resolution. A number of practical considerations also arise in the design process,

including system development and operational

costs; the technical maturity of a particular

design; and power, weight, volume, and data rate

requirements. Because it is extremely expensive,

or perhaps impossible, to gather data with all the

characteristics a user might want, the selection of

sensors or satellite subsystems for a mission

involving several tasks generally involves compromises (box 4-B).

Sensor performance may be measured by

spatial and spectral resolution, geographical coverage, and repeat frequency. In general, tradeoffs

have to be made among these characteristics. For

example, sensors with very high spatial resolution

are typically limited in geographical coverage.

Appendix B provides a detailed discussion of

these technical issues. It also discusses many

technical and programmatic concerns in the

development of advanced technology for remote

sensors and satellite systems.

24 co~mo~. 1870, ~ ~~~ bu~.~~ed, ~~-q~pp~ proto~ spacec~t WW+ ~~ched in 1987. Cosmos-1870 operated for 2 y-,

producing radar imagery of 25-30 m resolution.

25 tiller,A* Corp. WM formed to stimulate commercial use of the satellite data.
Global

Change

Research 5

G

lobal change encompasses many coupled ocean, land,

and atmospheric processes. Scientists currently have

only a modest understanding of how the individual

elements that affect climate, such as clouds, oceans,

greenhouse gases, and ice sheets, interact with each other.

Additionally, they have only limited knowledge about how

ecological systems might change as the result of human activities

(plate 7) and natural Earth processes. Because changes in climate

and ecological systems may pose a severe threat to mankind, but

the uncertainties in both are extremely large, the study of global

change has assumed major importance to the world. Consequently, scientists and concerned policymakers have urged

development of an integrated program of Earth observations

from space, in the atmosphere, and from the surface.

THE U.S. GLOBAL CHANGE RESEARCH PROGRAM

The U.S. Government has developed a comprehensive research program to gather data on global change and evaluate its

effects (box 5-A). The diverse elements of the U.S. Global

Change Research program (USGCRP) are coordinated by the

Committee on Earth and Environmental Sciences (CEES), a

committee of the Federal Coordinating Council for Science,

Engineering Sciences, and Technology (FCCSET), within the

Office of Science and Technology Policy.

The U.S. effort to study global change responds in part to an

international framework of research and policy concerns articu1 Uncertainties in possible adaptation strategies are also extremely large. See the

forthcoming report of an assessment of systems at risk from global change, Office of

Technology Assessment.

63
64 | Remote Sensing From Space

Box 5-A—U.S. Global Change Research Program

Global environmental and climate change issues have generated substantial international research activity.

Increased data on climate change and heightened international concern convinced the U.S. Government of the

need to address global change in a systematic way. In 1989, the Director of the Office of Science and Technology

Policy, D. AlIan Bromley, established an inter-agency U.S. Global Change Research Program (USGCRP) under

the Committee on Earth and Environmental Sciences.1 Established as a Presidential Initiative in the FY 1990

budget, the goal of the program is to provide the scientific basis for the development of sound national and

international policies related to global environmental problems. The USGCRP has seven main science elements:

. climate and hydrodynamic systems,

. biogeochemical dynamics,

. ecological systems and dynamics,

. earth systems history,

. human interaction,

. solid earth processes, and

. solar influences.

Participation in the USGCRP involves nine government agencies and other organizations.2 Research efforts

coordinated through the USGCRP seek a better understanding of global change and the effects of a changing

environment on our daily lives. Most research projects rely on remote observations of atmosphere, oceans, and

land for data. Coordination of research across agencies should eliminate duplication and increase cooperation,

and at minimum will promote communication between agencies. The Committee on Earth and Environmental

Sciences (CEES) makes suggestions to federal agencies, and federal agencies can raise items for consideration

through the CEES. Although this process can be cumbersome, most researchers acknowledge that the program

has brought a degree of coordination never before seen in federally sponsored research of this type. However,

the attempts at coordination do not assure a comprehensive program that tackles the most important issues. In

addition, now that the USGCRP is underway, it is no longer treated as a Presidential Initiative. This change of status

has led to concerns that funds previously “fenced off” for global change research will not be forthcoming.3

1 Forfirther information see Committee on Earth and Environmental Sdencesj OUr Changing P’MWt: 7h9W7%J3

U.S. G/ohal Change Research Program (Washington, DC: National Science Foundation, 1993).

2 Including the Smithsonian Institution and the Tennesee Valk3y Authofity.

3 These issues are addressed in a forthcoming OTA background paper, HE and the USGCRP.

SOURCE: Office of TAnology Assessrne~ 1993.

lated in reports of the Intergovernmental Panel on ing activities that cover a broad spectrum of

Climate Change (IPCC), the International Geo- global and regional environmental issues,’ by:

sphere-Biosphere Programme, and the World ● documenting global change,

Climate Research Programme (WCRP) and sup- . enhancing understanding of key processes,

ported by numerous national scientific panels.

The USGCRP is attempting to “produce a

and

predictive understanding of the Earth system to . predicting global and regional environmental

change.

support . . . national and international policymak2 Committee on Earth and Environmental Sciences, Our Changing Planet: The FY 1993 U.S. Global Change Research Program

(Washington DC: National Science Foundation, 1993), pp. 34.
Chapter 5-Global Change Research | 65

NASA’S MISSION TO PLANET EARTH

NASA established its Mission to Planet Earth

(MTPE) in the late 1980s as part of its program in

Earth sciences, MTPE includes the Earth Observing System (EOS), which consists of a series of

satellites capable of making comprehensive Earth

observations from space (figure 5-1);3 Earth

Probe satellites for shorter, focused studies (box

5-B); and a complex data archiving and distribution system called the Earth Observing System

Data and Information System (EOSDIS). Until

NASA launches the first EOS satellite, MTPE

research scientists will rely on data gathered by

other Earth science satellites, such as UARS,

the U.S.-French TOPEX/Poseidon,4 Landsat, and

NOAA’s environmental satellites. Data from the

EOS sensors may provide information that will

reduce many of the scientific uncertainties cited

by the IPCC--climate and hydrologic systems,

biogeochemical dynamics, and ecological systems and dynamics. 5 NASA has designed EOS to

provide calibrated data sets6 of environmental

processes occurring in the oceans, the atmosphere, and over land.

EOS science priorities (table 5- 1) are based primarily on recommendations from the Intergovernmental Panel on Climate Change and CEES of

the FCCSET. NASA has designed EOS to

return data over at least 15 years of operation;

its scientific value will be compromised if

measurements begun in the late 1990s do not

continue well into the next century. This raises

a critical issue for Congress: whether a commitment to an Earth Observing System, which may

require outlays on the order of $1 billion/year

in current dollars through about 2015, is

sustainable. Maintaining this level of investment

will require Congress’ continued interest in measuring climate and environmental parameters and

assessing the causes of global environmental

change in the face of other demands on the

Federal budget. It will also require continuing,

clear support from several presidential administrations.

NASA’S early plan for EOS was extremely

ambitious, technically risky, and costly. In 1991,

Congress told NASA that it should plan for

reduced future funding for the first phase of EOS

(fiscal year 1992 through fiscal year 2000), and to

cut its funding expectations from a projected $17

billion to $11 billion.7 This reduction led to a

major restructuring of the EOS program.8 In the

restructuring, NASA retained instruments that

focus on climate issues and reduced or eliminated

those that would have emphasized gathering data

on ecology and observations of Earth’s surface.

The restructured program’s first priority is

acquiring data on global climate change. As a

result, NASA has de-emphasized missions designed to improve scientific understanding of the

middle and upper atmosphere and of solid Earth

geophysics. The development of remote sensing

technology has also been affected by these shifts

as NASA has de-emphasized advanced sensors

for very high-resolution infrared, far-infrared, and

sub-millimeter wave spectroscopy. NASA also

3 See app. A for a summary of the MTPE instruments and satellites.

4 This U.S./French cooperative satellite was successfully launched into orbit Aug. 10, 1992 aboard an Ariane 4 rocket.

s t ‘OU Changing p~et: tie n 1991 Resewh Pl~’ The U.S. Global Change Reseach Program, a report by the committee on w

and Environmental Sciences, October 1990.

6 NASA has proposed to build and launch two sets of three satellites. The first set (called the AM satellite because it will follow a polar

orbit and cross the equator every morning) would be launched in 1998, 2003, and 2008. The second set (called the PM satellite) would be

launched in 2000, 2005, and 2010.

7 U.S. Senate, Committee on Appropriations, ‘‘Departments of Veterans Affairs and Housing and Urban Development, and Independent

Agencies Appropriation Bill, 1993, ” report to accompany H.R. 2519, 102-107, July 2, 1992, pp. 52-53.

s A number of scientists urged NASA to restructure the program on grounds of technicat and prograrnma tic risk. See, for example, *’Report

of the Earth Observing System (EOS) Engineering Review Committee, ’ September 1991; Berrien Moore III, “Payload Advisory Panel

Recommendations,” NASA manuscript, Oct. 21-24, 1991.
66 | Remote Sensing From Space

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Chapter 5 - Global Change Research |67

Box 5-B–NASA’s Earth Observing System (EOS)

EOS is the centerpiece of NASA’s contribution to the Global Change Research Program.

Managed by NASA’s newly created Mission to

Planet Earth Office,1 EOS is to be a multiphase

program lasting about two decades. The original

EOS plan called for NASA to build a total of six

Iarge polar-orbiting satellites, which would fly two

at a time on 5-year intervals over a 15-year

period. In 1991, funding constraints and concerns

over technical and budgetary risk2 narrowed its

scope.

The core of the restructured EOS consists of

three copies each of two satellites (smaller than

those originally proposed, and capable of being

launched by an Atlas II-AS booster), designed to

observe and measure events and chemical

concentrations associated with environmental

and climate change. NASA plans to place these

satellites, known as t he EOS-AM satellite (which

will cross the equator in the morning while on its

Figure 5-2—Artist’s Conception of NASA’s Earth

Observing System AM-1 Platform,

Scheduled 1998 Launch.

SOURCE: Martin Marietta Astro Space.

ascending, or northward, path) and EOS-PM satellite (an afternoon equatorial crossing) in polar orbits. The three

AM satellites will carry an array of sensors designed to study clouds, aerosols, Earth’s energy balance, and surface

processes (figure 5-2). The PM satellites will take measurements of clouds, precipitation, energy balance, snow,

and sea ice.

NASA plans to launch several “phase one” satellites in the early and mid 1990s that will provide observations

of specific phenomena. Most of these satellites pre-date the EOS program and are funded separately. The Upper

Atmosphere Research Satellite (UARS), which has already provided measurements of high levels of

ozone-destroying chlorine oxide above North America, is an example of an EOS phase one instrument. NASA’s

EOS plans also include three smaller satellites (Chemistry, Altimeter, and Aero), that will observe specific aspects

of atmospheric chemistry, ocean topography, and tropospheric winds. In addition, NASA plans to include data from

“Earth Probes,” and from additional copies of sensors that monitor ozone and ocean productivity, in the EOS Data

and Information System (EOSDIS).

NASA will develop EOSDIS3 so it can store and distribute data to many users simultaneously. This is a key

feature of the EOS program. According to NASA, data from the EOS satellites will be available to a wide network

of users at minimal cost to researchers through the EOSDIS. NASA plans to make EOSDIS a user-friendly,

high-capacity, flexible data system that will provide multiple users with timely data as well as facilitate the data

archiving process critical to global change research. EOSDIS willI require substantial amounts of memory and

processing, as well as extremely fast communications capabilities.

1 created in March 1993 when the Office of Space Science and Applications W= Split into tk ~f~ of Mission

to Planet Earth, the Office of Planetary Science and Astrophysics, and the Office of Life Sciences.

2 National Research Council Orange Book; “Report of the Earth observing System (EOS) EnginW~ng Re~ew

Committee,” September 1991.

3 I+ghes information Technology won the contract to develop EOSDIS In 1992.

SOURCE: Office of Technology Wmssment, 1993.
68 | Remote Sensing From Space

Table 5-1—EOS Science and Policy Prioritiesa

Water and energy cycles:

● Cloud formation, dissipation, and radiative properties, which

influence the scale and character of the greenhouse effects.

. Large-scale hydrology and moist processes, including

precipitation and evaporation.

Oceans:

. Exchange of energy and chemicals between ocean and

atmosphere and between ocean surface layers and deep

ocean.

Chemistry of troposphere and lower stratosphere:

● Links to hydrologic cycie and ecosystems, transformation of

greenhouse gases in atmosphere, and interactions with

climatic change.

Land surface hydrology and ecosystem processes:

. Improved estimates of runoff over surface and into oceans.

. Sources and sinks of greenhouse gases.

● Exchange of moisture and energy between land surface

and atmosphere.

Glaciers and polar ice sheets:

. Predictions of sea level and global water balance.

Chemistry of middle and upper stratosphere:

. Chemical reactions, solar-atmosphere relations, and

sources and sinks of radiatively important gases.

Solid Earth:

. Volcanoes and their role in climate change.

a List in approximate priority order; these priorities are based on a

program that would spend approximately $8 billion between 1991 and

2000.

SOURCE: Berrien Moore Ill and Jeff Dozier, “Adapting the Earth

Observing System to the Projected $8 Billion Budget: Recommendations from the EOS Investigators,” Oct. 14, 1992, unpublished document available from authors or from the NASA Mission to Planet Earth

Office.

reduced the size of the planned satellites and

increased their number. The restructured program

is now more resilient to the loss of a single

satellite during launch or in space operations, and

more capable of returning some data in the event

of fiscal or political changes. NASA also canceled or deferred some sensors that were either

unlikely to be ready for launch on either of the

frost two satellites in the EOS series or too costly

to include in the reduced funding profile.

In passing the fiscal year 1993 NASA appropriations, Congress further reduced NASA’s future

funding expectations for EOS by an additional $3

billion, an action consistent with NASA’s efforts

to reduce the costs of large programs. Between

fiscal years 1991 and 2000, NASA can now

expect to spend $8 billion for EOS ‘‘exclusive of

construction of facility, launch, and tracking

requirements, but including the Earth Observing

System Data and Information System (EOSDIS).1°

NASA has revised its restructured EOS program

to account for this projected funding level (box

5-C). As a consequence, NASA has reduced most

of the contingency funds, exposing the program

to the risk that it will be unable to complete some

instruments or may have to cut back on their

capacity to acquire certain data.

Additional large budget cut-backs may be

difficult to absorb; a third major restructuring

might result in the loss of several instruments.

Tight budgets have also precluded the development of system backups; this lack of redundancy

is an additional risk to the EOS program. The

existing $8 billion program is probably not the

program NASA would have designed if it had

begun planning EOS with such a budget in mind.

In fact, some scientists have suggested that by

planning a $17 billion program and Scaling back

in accordance with congressional and administration concerns over the future space budget, NASA

will be less effective in collecting data for global

change research. Nevertheless, the second restructuring still emphasizes the collection of data

on climate change, which is the highest priority of

the USGCRP. If Congress wishes to continue a

U.S. emphasis on global change research, it

should support the development of Mission to

Planet Earth at a level sufficient to accomplish

the science objectives of the U.S. Global

9 The reduction in platform size, which was strongly recommended in the ‘‘Report of the Ear& Observing System (EOS) En@e&ng

Review Committee,’ allows a reduction in the size and cost of the launch vehicles needed to boost these satellites to space. However, the overall

cost for the same data may well be higher eompsred to the original plan that used fewer, larger platforms.

10 U.S. Semte, Committee on Appropriations, ‘‘Departments of Veterans Affairs and Housing and Urban Development, and Independent

Agencies Appropriation Bill, 1993,” report to accompany H.R. 5679, 102-356, July 23, 1992, pp. 145-147.
Chapter 5-Global Change Research |69

Box 5-C-The Revised, Restructured

EOS Program (1993)

In revising the EOS program from its restructured

expected funding level of$11 billion to $8 billion over

the decade from 1991-2000, NASA:

●

●

●

●

Reduced the amount of contingency available for

handling unexpected problems in instrument

development and changes in the science requirements. This has the effect of increasing the

financial and technical risk to the program, but it

maintains the core instruments on the EOS AM

and PM platforms.

Further increased cooperation with European

and Japanese partners in EOS. While this

spreads the development burden, it also increases the amount of international program

coordination required. It also reduces U.S. influence over the development process. For example, the United States will leave to its partners the

development of advanced instruments for active

microwave sensing.

Canceled the proposed LAWS and EOS SAR

instruments, deferred HIRIS, and moderately

descoped other proposed instruments.

Reduced the amount of EOSDIS funding by 30

percent, which forced reductions in the number of

EOSDIS products available to researchers.

SOURCE: “Adapting the Earth Observing System to the Projected

$8 Billion Budget: Recommendations from the EOS Investigators,”

Berrien Moore Ill, and Jeff Dozier, eds, Oct. 14,1992. Manuscript.

Change Research Program. Although NASA

was able to absorb substantial reductions of its

proposed long term EOS budget by deferring

several expensive instruments and concentrating on climate research, additional major cuts

in NASA’s MTPE budget could sharply reduce

the effectiveness of NASA’s research.

As noted above, the restructuring of EOS has

shifted NASA priorities and affected instrument

selection. As a result:

●

●

NASA has reemphasized measurements of

upper atmospheric chemistry in the belief

that data from existing satellites such as the

Upper Atmosphere Research Satellite (UARS

—figure 5-3), supplemented by planned

Shuttle ATLAS missions and in-situ airborne and balloon measurements, will be

sufficient to monitor ozone depletion and

assess the effectiveness of congressionally

mandated phase-outs of chlorofluorocarbons (CFCS). NASA has no plans to launch

a satellite designed to acquire equivalent

data after UARS fails .11 However, continued

satellite measurements will be needed to

monitor the health of Earth’s protective

ozone layer, to guard against scientific

surprises, and to provide the necessary

scientific rationale for international protocols that limit emissions of ozone-depleting

gases. Long-term information about the state

of the ozone layer will be particularly

important for developing nations where the

relative cost of limiting CFC emissions may

be highest. NASA intends to provide some

of the necessary data with its TOMS instruments.

Some relatively inexpensive, small satellite

projects are threatened with delay or cancellation—for example, the Active Cavity Radiometer Irradiance Monitor (ACRIM),12

which would be used to continue measurements to monitor the variability of total solar

irradiance, may not fly until 2002. Similar

concerns exist for SAGE, an instrument

designed to monitor tropospheric aerosols.

NASA has dropped other advanced technology instruments because of a reduced emphasis on atmospheric chemistry research.

Some researchers express concern that in

canceling these instruments, the United

States will lose the opportunity to make

important climate measurements and risk

I I u~s ~ plm~ Ovration may extend through 1994. Individual instruments and components ~Y f~l ~li~,

12 On etilier flights of ACRIM.
70 | Remote Sensing From Space

Figure 5-3-Artist’s Conception of NASA’s Upper

Atmosphere Research Satellite

SOURCE: Martin Marietta Astro Space.

reductions in the U.S. technology base for

developing advanced instruments.

NASA has cancelled three important proposed instruments: Laser Atmospheric Wind

Sounder (LAWS),13 Synthetic Aperture Radar

(SAR), 14 and High Resolution Imaging Spectrometer (HIRIS).15 All are technically challenging and very expensive to develop.l6 All

are also “facility” instruments that would

acquire data of interest to a large number of

investigators.

Although the technical complexity and challenge of the original EOS program, along with the

lack of available funds, has forced many of these

changes, data from these instruments would make

significant contributions to our understanding of

the Earth as an interactive system and of global

change. If further research demonstrates that

these or similar instruments are needed to support

additional progress in understanding global

change, Congress may wish, before the end of the

century, to consider supplemental funding for

their development.

In the meantime, NASA should continue to

develop technology and scientific research related to these technologies and find ways to

reduce system costs. Increased cooperation

with the DOE-operated national laboratories

offers a particularly attractive mechanism to

develop the technology base that will be required for next-generation sensors and spacecraft. Lawrence Livermore National Laboratory,

Los Alamos National Laboratory, and Sandia

National Laboratories, in particular, have considerable expertise in spacecraft instrument design.

DOE has proposed collaborative projects focusing on the acquisition of data about Earth’s

radiation budget, an important component

of DOE’s Atmospheric Radiation Measurement

(ARM) program. They have also proposed collaborative projects to develop hyperspectral sensing

that could be mounted on satellites or aircraft (the

DoD also has an aircraft-based program to

develop hyperspectral sensors-’ ’HYDICE’ ‘).

International cooperation can offer a means to

increase the capability of collecting important

environmental data while reducing costs for any

single government. In order to ease its own cost

burden for sensors and satellite systems while

maintaining the capability to monitor important

features of Earth’s environment, NASA has

reduced funding for certain sensors and enhanced

its cooperative remote sensing programs with

other countries. Japan and the European Space

Agency are being asked to take on the development of several sensors that would fly on U.S.

spacecraft and to provide space on their spacecraft for U.S. sensors. However, international

cooperative arrangements can only fill part of the

void left by the rapid restructure of EOS. Some of

13 ~r dh~~ m-ement of tropospheric winds at high resolution.

M For -g hi@ resolution radar images of lant oceatL and ice sw’faces.

IS For&g high spa~ resolution images of Earth’s surface in some 200 contiguous, vexy narrow infrared and visible specmal reds.

16 SW app, B for a mom extensive discussion of these instruments and their development.
Chapter 5 GIobal Change Research |71

Table 5-2—The Current EOS Spacecraft Program

1998

2003

2008

1988

2000

2003

2006

2009

2012

2000

2005

2010

2002

2007

2012

2002

2007

2012

SOURCE: 1993 EOS Reference Handbook, EOS Program Chronology.

the scientific objectives must be deferred until

new domestic or foreign funding sources are

made available.

Increased international cooperation in remote

sensing is possible because over the past decade

other countries have markedly improved their

skills in sensor development and satellite systems

integration and construction. Canada, France,

Germany, the United Kingdom, Japan, Russia,

China, and India have made satellite remote

sensing a priority. Prospects for greater international cooperation will increase as the remote sensing programs of other countries

grow in technical breadth and capability.

Some policymakers express the concern that

increased cooperation will boost the technical

capabilities of other countries by giving foreign

industry a chance to develop technology in which

the United States has a strong lead. In addition,

because foreign experience with some systems is

less well developed than that of U.S. industry,

some scientists fear sensors developed abroad

might be less capable than ones built domestically, leading to incomplete data sets. Hence, in

order to ensure that the United States does not

forfeit the lead in technical capabilities it

considers vital to national competitiveness,

Congress may wish to scrutinize closely the

structure of any international agreements in

remote sensing.

Another problem with international cooperation is that each country has a strong interest in

providing the most advanced instruments or

systems. The outcome is that a cheap, simple

satellite design can quickly grow into a relatively

expensive, complex system.

NASA expects to operate EOS and EOSDIS for

at least 15 years after the launch of the second

major satellite (PM-1) in 2000 (table 5-2). Therefore, the program will necessarily take on the

characteristics of what has been called an ‘operational program’—in other words, sustained, routine acquisition of data that must be routinely

available to researchers and other users on a

timely basis. To achieve maximum effectiveness, NASA’s EOS Program must be organized and operated with great attention to the

regular, timely delivery of data. This means, for
72 | Remote Sensing From Space

example, not only that EOSDIS (box 5-D) function smoothly, and in a “user friendly” manner,

but that the sensor systems that feed data into

EOSDIS are prepared to deliver vast amounts of

data with few processing errors or system slowdowns.

STRUCTURING A ROBUST RESPONSIVE,

GLOBAL CHANGE RESEARCH PROGRAM

NASA plans to use EOS to provide scientists

with data relevant to questions that often

polarize public debate regarding climate

change and its global environmental effects.

Although these data may help resolve some

contentious scientific issues, they may not

produce results that lead to clearcut policy

decisions. Data from instruments aboard EOS and

other satellites, as well as from many other

sources, will be used to study the effects of global

change and to predict possible future changes in

Earth’s environment. Unlike the recent observations of ozone-destroying chlorine molecules in

the upper atmosphere, which quickly led to a

speedup in the phase-out of U.S. chlorofluorocarbon

(CFC) production, few of the research questions

that can be addressed by the USGCRP will result

in straightforward policy responses. Most of

these data will provide inputs to complex

models intended to predict future climatic and

environmental conditions. Because of the complexity of the models, finding sufficient scientific

agreement to draw definitive conclusions for

policymakers to act on may be especially difficult. Although scientific research may provide

evidence linking the production of particular

gases to deleterious climate changes, predicting

regional environmental changes that could signal

major economic disruptions may not be possible

for decades. Moreover, even when the facts are

known and the processes understood, proposed

solutions may not necessarily be clear or uncontentious. However, the best chance the United

States has to develop the scientific basis for

good policy is to pursue the best science, based

on a robust, responsive global change research

program. Such a program would include a

strong commitment to making observations

from instruments based in aircraft, ships, and

ground facilities, as well as from space.

| Existing Satellite Systems

Most existing space-based remote sensing

instruments contribute in some way to global

change research-NOAA’s environmental satellites, the Landsat system, and NASA’s research

satellites. For example, the polar-orbiting NOAA

POES satellites (box 3-D) carry the High Resolution Infrared Radiation Sounder (HIRS) and the

Microwave Sounding Unit (MSU), which daily

measure atmospheric temperature and humidity,

and the Advanced Very High Resolution Radiometer (AVHRR), which can be used to monitor the

global state of vegetation, the extent of Arctic and

Antarctic ice pack, and sea surface temperatures.

Observations from both instruments contribute to

research on global change. In general, NOAA

instruments provide the long-term data sets necessary for identfying previous trends (plate 9).

However, because the instruments in NOAA’s

environmental satellites were designed to serve

NOAA’s needs in collecting weather and climate data, these instruments lack the necessary calibration to gather precise data required for sensing and interpreting subtle,

gradual changes in the environment. Sensors

aboard future NOAA satellites ought to be

designed to provide data having better calibration.17

Remotely sensed data from Landsat, SPOT,

ERS-1, JERS-1, and other satellites optimized for

imaging surface features will become increasingly important in following local, regional, and

global environmental change (plate 7). Landsat

and SPOT have contributed significant quantities

17 ~ovi~g better Ctibmtion will add to the cost of the SCIISOrS, how~ti.
.

Chapter 5-Global Change Research |73

Box 5-D—Earth Observing System Data and Information System

EOSDIS will consist of 8 interlined Distributed Active Archive Centers (DAACS) and a Socioeconomic Data

and Applications Center (SEDAC) that will archive original data, create scientific data products, and make them

available to users either at t he centers or on line. NASA plans to spend about $1.5 billion on the development and

operation of EOSDIS. This investment will result in a large number of data sets that can be accessed repeatedly

by various users. Handling large data sets in an open network presents many challenges, and will push the state

of the art in software and communications hardware. EOSDIS will be the key link between the data collected by

the satellite systems and the scientists working on global change research.

EOSDIS will challenge NASA’s technical and organizational skills in part because the system and its data

products cannot be well-defined at this early stage. The data storage and retrieval system will require new image

processing techniques capable of handling interrelated data sets, and a transparent “window” for the user. The

system must be able to run in multiple operating environments, and be accessible by people possessing different

levels of computer skills. EOSDIS will require innovative solutions to data handling that will take years to develop.

EOSDIS will also require improved data compression and decompression algorithms. These compression

schemes must work at extremely fast data rates, yet not degrade data integrity. Maintaining the data securely is

a priority for any large data system, and it will be extremely challenging for an EOSDIS that will be open to hundreds

and eventually thousands of users.

If EOS data can reduce scientific uncertainty surrounding atmospheric and environmental changes, the

program will be a success. A successful EOS will depend largely on the ability of EOSDIS designers and managers

to create a system in which massive amounts of data can be archived, cataloged, maintained, and made routinely

accessible to users, and which will maintain the integrity of the data.

NASA’s first objective is to expand the amount of earth science data available to the scientists. With help from

the science user community, it has identified large, “pathfinder,” data sets for inclusion in EOSDIS Version O.

Pathfinder sets will include data that have been collected over many years by operational satellites such as NOAA

polar orbiters and geostationary satellites and Landsat. EOSDIS will serve as the archive for these data sets, which

will assist global change researchers and allow NASA contractors gradually to improve EOSDIS based on

experiences of initial users. According to t he General Accounting Office, progress on gathering and reprocessing

pathfinder data has been slow.1 Only one complete data set is expected to be available by 1994, and only three

complete data sets will be available by 1996. Slow progress on pathfinder data sets may impede planning and

development for latter phases of EOSDIS.

I U.S. Congress, General Accounting Office, “Earth Observing System: Information on NASA’s Incorporation of

Existing Data Into EOSDIS,” September 1992.

SOURCE: Office of Technology Assessment, 1993.

of high-quality data to archives that can be used | Small Satellites

to provide early indications of harmful change in As instruments aboard satellite svstems irnlocalized areas.l8 Existing data, especially those prove, they are likely to assist in the development

being prepared under the Pathfinder EOSDIS of much needed information about the global

efforts, need to be studied in detail to understand environment and how it is changing. However, as

better how to use remotely sensed land data in currently structured, satellite systems may not

global change studies. provide some of the most urgently needed data

18 see ~t~ew D, f’ro~~, H1~torica[~&~at Daf~ compan”~on$: I[l~s~~hOns of~ndsu~ace change ~as~ton, DC: U.S. (koIO@Cid

Survey, 1993), for a sample of the surfaw changes that Landsat data are capable of revealing. Beeause these digital data can be readily sorted

and manipulated in a computer, and merged with other data, they can be used to make quantitative estimates of change.
74 | Remote Sensing From Space

in time to assist the policy debate. In addition,

the United States has no plans for monitoring

aspects of global change on decadal timescales.

Yet, many climatologists and other scientists

believe that monitoring on this timescale will be

essential to 1) build databases over sufficiently

long periods to support global change research

and refine predictive models, and 2) monitor the

often subtle climatic and ecological changes

induced by anthropogenically produced gases and

other pollutants.19

Moreover, some researchers argue that the

appropriate instrument platforms to carry out

decadal-scale measurements are not the large,

complex, and expensive satellites planned for

the EOS program. These researchers argue that

a balanced program for global change research

would include smaller, less expensive, and less

complex satellites that would be developed specifically for particular monitoring missions,20

Several agencies, including NASA, DOE, and

ARPA, are examining the use of small satellites

for global change research. Small satellites,

which have been defined as costing $100 million

or less, including spacecraft, instruments, launch,

and operations, could:21

●

●

●

address gaps in long-term monitoring needs

prior to the launch of EOS missions,22

provide essential information to support

process studies prior to, and complementary

with, the restructured EOS,

allow for innovative experiments to improve

the ability to monitor key variables or improve/speed up the process studies.23

Matching small instruments with small satellites has several potential advantages: First, it

avoids the necessity of integrating multiple instruments on a single platform-this simplifies

the acquisition process, albeit at a possibly higher

overall cost. Second, shortening the time to

launch would add resilience to the satellite

portion of the global change research program,

large parts of which are frozen in development

some 10 years before flight. Third, flying only a

small number of instruments per satellite allows

scientists to optimize the satellite orbit for a

particular set of measurements.24 Finally, flying

small instruments on small satellites increases the

likelihood that a small core of key environmental

sensors can:

●

●

●

be launched before the EOS system and thus

prevent data gaps that would otherwise be

created in the mid-to-late 1990s (before EOS

launches);

be maintained even if EOS suffers further

cutbacks; and

be maintained for years beyond the scheduled 15-year lifetime of the EOS system.

However, the funding for such satellites would

have to come from some other source than the

EOS program, Otherwise, the deployment of the

first EOS satellites (AM-1998; PM—2000)

would risk being delayed.

Global change researchers express widespread

agreement on the desirability of using small

satellites for these three roles. However, scientists

express sharp disagreements about the long-term

19 For e~ple, the burning of fossil fuels, use of CFCS, and agriculture.

m Liz lbcci, “EOS Backers Push for Faster Launches, ” Space News, Mar. 29, 1993, p. 14.

21 Sti Cotittee on ~and Environmental Sciences (CEES) of the Federal Coordinating Council for Science, Wnee@, and

Techr.vlogy, Report of the Small Climate Satellites Workshop (Washington DC: Office of Science and Technology Policy, May 1992).

22 Gw.fi@ spacwr~ were fi~y proposed in 1991. With the frost EOS launch scheduled fOr 1998, the oPPotitY for usfig these

spacecraft is fast drawing to a close.

23 Repoti of the Smzl C/iwte Satellites Worbhop, pp. 20-21. As noted in the texti researchers at the God&d ~titute for SPace Studies

have also proposed using small satellites for long-term (decadal-scale) monitoring in a program that would complement EOS.

24 Some fissions ~uke naly sfiul~neous m~u~men~ by ~struments tit c~ot k pachged on a single, sfrdl satellite. b thiS case,

a larger platform carrying several instruments may be desirable. Alternatively, small satellites could be flown in close formation.
Chapter 5 -Global Change Research |75

potential for small satellites to replace larger,

more expensive satellites such as Landsat. Advocates of small satellites believe satellite weight

and volume can be reduced by incorporating

advanced technologies, now in development,

with next generation spacecraft. However, proposed new instrument technologies are typically

at an early stage of development and their

capability to provide the stable, calibrated measurements required for global change research is

likely to be unproved, Stability and calibration

requirements are particularly important for longterm monitoring. Fully developed data processing

systems and well-understood data reduction algorithms are also required to transform raw data into

useful information.25

Historically, satellite designers have minimized risk by introducing advanced technology in

an evolutionary manner; typically, only after it

has been proven in the laboratory and acquired a

heritage of space worthiness. Although experts

generally agree on the desirability of accelerating

this relatively slow process, they do not agree on

the risk that would be associated with a change in

the traditional development cycle.26 The risks in

developing a new sensor system have two

components: the technical maturity of component technologies (for example, the detector

system), and the design maturity. A particular

design that has not been used before may be a

relatively risky venture for an operational

program, even if it is based on proven technology. Several proposals have been made to reduce

the risks of inserting new technologies into

operational programs. Box 5-E summarizes one

Box 5-E-The Advanced Research Projects

Agency CAMEO Program

ARPA has proposed several advanced technology

demonstrations (ATDs) on small satellites that, if

successful, would rapidly insert technology and shorten

acquisition time for larger satellites.’ These demonstrations would couple innovative sensor design with a

scalable high-performance common satellite bus that

would employ a novel “bolt-on” payload-bus interface.

ARPA-proposed ATDs include ATSSB (advanced

technology standard satellite bus) and CAMEO (collaboration on advanced multi-spectral Earth observation). They were fully supported by the Department of

Defense, but were eliminated by the Senate Appropriations Committee for fiscal year 1993.

I See app. B for more detail on this proposal.

SOURCE: Advanced Research Projects Agency, 1993.

example from the Advanced Research Projects

Agency.

To date, budget constraints, scientific disputes over the merits of specific proposals,

intra-agency and inter-agency rivalries, and

the absence of a coherent strategy, developed

within the executive branch and supported by

the relevant authorization and appropriation

committees of Congress, has limited efforts to

develop and flight-test emerging technologies.

Appendix B discusses these issues at greater

length along with specific proposals for launching

small EOS satellites. Appendix B also notes that

the development of innovative, lightweight sensors appropriate for small satellites and the

development of sensors for long-endurance, highaltitude UAVS share many common features.

25 AII illus~ative Cxmple is given by the complex analysis that is required to measure the Earth’s radiation budget (see app. B).

26 A p~ed development cyc]e has traditio~y been used to procure operational SyStemS. The Steps in tfis cycle cm be grouped as follows:

Phase A—Study Alternate Concepts;

Phase B—Perform Detailed Design Deftition Study (manufacturing concerns addressed in this stage);

Phase C—Select Best Approach/Buitd and Test Engineering Model;

Phase D-Build Flight Prototype and Evaluate on Orbit.

This approach should be contrasted with a ‘‘skunk-works’ approach which omits some of these steps. HistoricaUy, the skunk-works

approach has usually been thought more risky than the methodical approach. As a result, it has been used mostly for demonstrations and

experiments.
76 | Remote Sensing From Space

Box 5-F-Radiative Forcings

and Feedbacks

Radiative forcings are changes imposed on the

planetary energy balance; radiative feedbacks are

changes induced by climate change. Forcings can

arise from natural or anthropogenic causes (see table

5-3). For example, the concentration of sulfate aerosols in the atmosphere can be altered by both volcanic

action (as occurred following the eruption of Mt.

Pinatubo in June 1991) or from power generation

using fossil fuels. The distinction between forcings and

feedbacks is sometimes arbitrary; however, scientists

generally refer to forcings as quantities that are

normally specified, for example, CO2 amount, while

feedbacks are calculated quantities. Examples of

radiative forcings are greenhouse gases (C02

, CH4,

CFCS, N20, OS, stratospheric H20), aerosols in the

troposphere and stratosphere, solar irradiance, and

solar reflectivity. Radiative feedbacks include clouds,

water vapor in the troposphere, sea-ice cover, and

snow cover.

SOURCE: office of Technology Assessment, 1993 and Dr. James

Hansen, Goddard Institute for Space Studies.

Present and future global climate change cannot be interpreted without knowledge of changes

in climate forcings and feedbacks (box 5-F).

“Climsat” is the name of a proposed system of

environmental satellites that would carry out

long-term monitoring of the Earth’s spectra of

reflected solar and emitted thermal radiation.

Climsat satellites would be flown in pairs, one in

polar and the other in inclined orbit.27 Each would

carry three small, lightweight instruments (see

box 5-G). Climsat satellites would be selfcalibrating,

28 small enough to be orbited with a

Pegasus-class launcher,29 long-lived (nominally

10 years or more), and relatively inexpensive.30

The originators of the Climsat proposal believe it

could provide most of the missing data required

to analyze the global thermal energy cycle,

specifically long-term monitoring of key global

climate forcings and feedbacks. In addition,

proponents claim Climsat would be a more

“resilient” system than EOS because it would

launch a small complement of relatively inexpensive instruments on small satellites. However,

Climsat alone is not intended to fulfill the

broader objectives of the Mission to Planet

Earth and the Earth Observing System Program.

Monitoring of global radiative forcings and

feedbacks is essential to understanding the

causes, time-scale, and magnitude of potential

long-term changes in global temperature. However, a program to correlate changes in average

temperature with changes in radiative forcings

and feedbacks is expected to require measurements that would extend over decades. Unlike

EOS satellites, which NASA proposes to fly for

a total of 15 years, Climsat satellites would be

operated for several decades.31

27 AS describ~ k tie text, two ~telliles are specified in the Clirnsat proposal because this n-r is necessary for global COverage and

adequate sampling of diurnal variations.

~g SAGE calibration is obtained by viewing the sun (or moon) just before or after every occultation. MINT records its interferogram on a

single detector and therefore would have high wavelength-to-wavelength precision. EOSP interchanges the roles of its detector pairs

periodically. Stable internal lamps are used for radiance calibration.

‘g A launch on Pegasus costs about $10-12 million. Pegasus can carry payloads weighing up to 900 pounds.

Jo Cost estimates are uncetiatan~ly stage of concept deftition, However, two of the three Climsat iftSttUmeINS hWgOne throughpbe

A/B studies k EOS. kading Goddard Institute of Space Studies researchers to make the following estimates:

SAGE III-$34 million for 3 EOS copies (18 million for fmt copy);

EOSP---$28 million for 3 EOS copies ($16 million for fwst copy);

MINT+i15-20 million for fwst copy.

31 EOS ~ffici~s ag& tit d~a~-s~e mofito@ of tie~ is needed; they foresee some subset of EOS instruments evolving irlto

operational satellites designed for long-term monitoring.
Chapter 5 -Global Change Research |77

Table 5-3-Human Influence On Climate

Both the initial EOS program and the initial

Climsat proposal have been revised since their

initial presentations. Versions of two of the three

Climsat instruments are now scheduled for flight

on later EOS missions. However, Climsat supporters argue that flying these instruments as part

of Climsat would:

●

●

●

●

allow flight in proper orbits;

guarantee overlapping operations (over longer

periods), which would result in better calibrated measurements;

allow launch several years before the relevant EOS platforms;32 and

allow instrument modification on a shorter

time-scale than EOS instruments and thus be

better able to respond to scientific surprises.

Supporters also argue that Climsat instruments

are better designed to handle scientific surprises

because:

●

●

unlike related larger instruments on EOS,

they cover practically the entire reflected

solar and emitted thermal spectra, and

the Climsat instruments measure the polarization as well as the mean intensity of the

solar spectrum where polarization is highly

diagnostic of the observed scene.

A key argument in favor of the Climsat

proposal is its potential to carry out a core group

of key remote sensing measurements on a decadal

time-scale. In effect, supporters of Climsat argue

that the data that would be gathered by Climsat—

or a similar system-is too important to be tied to

the budgetary fate and schedule of EOS. Detractors of the Climsat proposal include those who

believe that its funding could come only at the

detriment of an already diminished EOS program.

Further, they contend that Climsat addresses only

a narrow part of the climate problem. For

example, they question whether data from

Climsat are, in fact, more important than data on

ocean color, land-surface productivity, atmospheric temperature and humidity, and snow and

ice volume.

| Complementing Satellite Measurements

Satellites alone cannot carry out a robust

program of global change research, Orbiting

above the atmosphere, a satellite remote sensing

system receives information about atmospheric or

terrestrial processes only via electromagnetic

signals reflected or emitted from the atmosphere

or the surface. Sensors collect these signals and

transform them into forms that can be used as

input data for analysis and interpretation. Scientists need to compare satellite data with surfacebased or airborne measurements to verify that the

satellite data are free of unforeseen instrument

32 Dr. Jme~ H~~n, d~v~loper of tie Clfisat pmps~, esti~tes titfie Cbsat satelfite wo~d re@re 3 years to build and bi~ch after

approval and procurement processes are complete.
78 I Remote Sensing From Space

Box 5-G - The Data Storage Problem

The sheer size of archives for remotely sensed Earth data can be estimated through some simple

calculations. The data storage requirement is the product of the storage needed for each pixel and the number

of pixels. Such a calculation is done in terms of “bits,” the O’s and 1’s used in computers’ binary arithmetic.

As an example, consider an Earth’s worth of Landsat-like pictures from a notional satellite with 10 bands, each

imaging 25- X 25-meter pixels in terms of 32 brightness levels. The 32 gradations of brightness are expressed

by 5 bits, so each square kilometer, consisting of 1,800 pixels, requires 1,800X 10X 5 = 80,000 bits, or 10

kilobytes. (For comparison’s sake, this box requires about 2 kilobytes of computer storage.) The Earth’s 200 million

square kilometers of land, therefore, would require 2 billion kilobytes of storage capacity.

Two billion kilobytes is roughly the storage capacity of 20 million late-model home computers or 3,000

compact disc recordings.

The Human Genome Project, to take another example of data collection and storage, will not have to deal

with nearly this much data. The genome consists of 3.3 billion base pairs, each embodying 1 bit. Thus the genome

is “only” 3,300 megabits, or about 400 megabytes-about the contents of half a compact disc.

To observe change, or the most current situation, further pictures are needed and must be stored. Each adds

another 2 billion kilobytes. Inclusion of the water-covered three-quarters of the Earth’s surface would increase the

size of each picture to 8 billion kilobytes, and “hyperspectral” techniques, involving 100 bands instead of 10, would

increase storage needs an additional tenfold.

SOURCE: office of Technology Aseeesment, 1993.

artifacts or unforeseen changes in instrument mounted faster on an aircraft or balloon expericalibration. These comparisons are particularly ment than on a satellite. Furthermore, as noted

important for long-term measurements and for earlier, the development of instrumentation on

measurements that seek to measure subtle changes. airborne platforms greatly assists the developSatellite data must also be corrected to account for ment of space-qualified instrumentation for satelthe attenuation and scattering of electromagnetic lites. However, balloons and aircraft cannot be

radiation as it passes through the Earth’s atmos- used for monitoring global phenomena that have

phere. In addition, corrections are necessary to small-scale variability because their coverage is

account for the variations in signal that occur as limited in time (intermittent coverage, weather

a result of changes in satellite viewing angle. restrictions) and space (altitude ceilings, geoNonsatellite data can also assist in the analysis of graphic restrictions).

satellite data by clarifying ambiguities in the

analysis and confirming certain measurements.

Finally, sensors on satellites may be limited in | Process Studies and Unpiloted Air

their capability to make measurements in the Vehicles

lower atmosphere, and they may be unable to “Process”3 3 studies, which are necessary to

make the detailed measurements required for understand global forcings and feedbacks in

certain process studies. detail, require ground and in situ measurements.

Balloons and aircraft are generally more “re- For example, a detailed understanding of the

sponsive” than satellites: in general, an experi- kinetics and photochemistry that govern the

ment to monitor a specific process can be formation of the Antarctic ozone hole (and the

33 ~e~ is no clear delineation between “process” studies and monitoring studies. In gener~ global change researchers use the term

‘‘process study’ to refer to shorter term less costly, and more focused experiments that aim to elucidate the details of a particular mechanism

of some geophysical, chemical, or biological interaction.
Chapter 5-Global Change Research |79

role of the Antarctic vortex) has only been

possible with in situ balloon and high-altitude

34 Development of high aircraft measurements.

altitude unpiloted aircraft would extend these

measurements, which would be especially useful

in elucidating the mechanisms that cause significant loss of ozone over the Arctic and northern

latitudes.

High-altitude unpiloted air vehicles (UAVS)

offer significant advantages over satellites for

measuring some upper atmospheric constituents.

In particular, they can be used for accurate in situ

measurements-actually sampling the constituents of the upper atmosphere and using the

samples to decipher, for example, the chemical

reactions taking place among stratospheric ozone,

chlorine monoxide, bromine monoxide and other

man-made substances. Because instruments on

UAVS can be changed or adjusted after each

flight, UAVS are also potentially more responsive

than satellite systems to new directions in research or to scientific surprises. Unlike balloons,

they move through the air, rather than with it,

allowing operators to guide their paths.

In addition to its use of high-altitude balloons

and piloted aircraft, NASA plans to employ a

small UAV called Perseus, developed by the

small private firm, Aurora Flight Services, Inc.3s

for atmospheric studies. The first two Perseus

aircraft (Perseus A) are scheduled for delivery to

NASA at a cost of about $1.5 to $1.7 million each.

NASA will initially use sensors carried on

Perseus to determine the chemistry and movement of gases in the stratosphere at altitudes up to

approximately 25 kilometers (82,000 feet).

UAVS may provide global change researchers

with low-cost and routine access to regions of the

atmosphere that are inaccessible to piloted aircraft, sampled too infrequently by balloon, and

sampled too coarsely by satellites. UAVS should

also be highly cost effective in providing crucial

in situ measurements of atmospheric chemical

constituents. They are also a natural test-bed for

small, lightweight instruments proposed for flight

on small satellites. Despite their potential to

enable measurements that are crucial for the

global change research program, government

support for UAV development, and associated

instrumentation, has been meager and may be

inadequate to provide a robust UAV capability. If Congress wishes to encourage innovation in global change research, it may wish to

increase funding for UAVS. Because of their low

development costs, moderate funding increases of

only a few million dollars could ultimately lead to

a substantial increase in UAV availability for

research. 36

Satellites view the Earth only from above the

atmosphere; this limits their measurement of two

physical quantities of interest to global change

research. One, the angular distribution of radiation, is necessary for measurements of Earth’s

radiation budget.37 The other, the ‘‘flux divergence, ’ can be related to the net heating that

occurs in a particular layer of the atmosphere. It

is a fundamental parameter in global circulation

models of Earth’s atmosphere and climate. UAVS

are ideally suited to make these measurements

and would complement groundbased observa34 J,G. Andersou D.W, Toohey, W’.H ‘~e~ ‘‘Free Radicals Within the Antarctic Vortex: The Role of CFCS in Antarctic Ozone Lmss,’

Science, vol. 251, Jan. 4, 1991, pp. 39-46.

35 Richard Monastersky, ‘ ‘Voyage Into Unknown Skies, Science News, V01,139, Mar, 2, 1991, pp. 136-37; Michael A. Dornheirn, ‘‘Perseus

High-Altitude Drone to Probe Stratosphere for SST Feasibility Studies, ” Aviation Week and Space Technology, Dec. 9, 1991, pp. 36-37.

36 NASA is now askfig for additio~ ~d~g of $90 ~ion ovm 5 years to build and fly (JAVS for scientilc research.

37 me ~,s ~ ~r~lation budget’ comis~ of ~cident sutight minus reflected sunlight (for example, from the tops of clouds) and radiation

emitted back to space, primarily from Earth’s surface and atmosphere. The emitted radiation falls predominantly in the infrared and far-inffared

portion of the electromagnetic spectrum. Earth’s average temperature rises or falls to keep the total incoming and outgoing energy equal.

Changes in the amount of energy entering or leaving Earth result in global warming or cooling.
80 I Remote Sensing From Space

tions made in the Department of Energy’s atmos- system integrating high-quality measurements of

pheric radiation program (ARM) .38 atmospheric winds, temperature, and moisture,

Groundbased observations in DOE’s ARM would serve to calibrate satellite measurements in

program also provide an important source of portions of the atmosphere in which measurecalibration data for space-based observations of ments of the satellite and groundbased instruatmospheric solar heating. Likewise, NOAA’S ments overlap.

proposed Telesonde program,39 a groundbased

38 U.S. Dep~~t of Enqy, Office of Hea.lti and Environmental Researck Atmosphen”c Radiation Measurement UWIUnnedAerOwace

Vehicle and Satellite Program Plan, March 1992 draft (Washingto~ DC: Department of Energy, March 1992). Also see Peter Banks et. al.,

Small Satellites andRPAs in Global-Change Research, JASON Study JSR-91-33 (McLean, VA: JASON Program OffIce, The MITRE Corp.,

July 13, 1992).

w “M~gement ~omtio%” Wave fiopagation Laboratory, National OCeaniC ~d Atmospheric A*@itioQ October 1990.
Military Uses

of Civilian

Remotely

Sensed

Data 6

D

ata from civilian satellites systems such as Landsat, but

more notably SPOT and the Russian Almaz,l have

considerable military utility. They can be used to

SUDDOrt:

●

●

A L

Military operations—For example, the use of Landsat and

SPOT data gave the United States and its U.N. allies a

marked advantage over Iraq in the Persian Gulf Conflict.

The U.S. Defense Mapping Agency used these data to create

a variety of maps for the U.S.-led battle against Iraqi forces

(figure 6-l). More recently, in March 1993, the United

States has used Landsat and SPOT data to create maps of the

former Yugoslavia in support of air delivery of food and

medical supplies to besieged towns of Eastern Bosnia.

Reconnaissance —The recent use of data from civilian

satellites for military reconnaissance demonstrates that

post-processing, skilled interpretation, and the use of

collateral information can make these data highly informative. For this reason, the civilian satellites’ utility in

reconnaissance exceeds that which might be expected on the

basis of ground resolution.2 The highly conservative rules

of thumb normally used to relate ground resolution to

suitability for particular reconnaissance tasks underestimate

the utility of moderate resolution multispectral imagery.

However, reconnaissance missions’ requirements for

timeliness often exceed the current capabilities of civil1 In October 1992, Almaz, which had been transmitting data from its synthetic

aperture radar, fell back into the atmosphere and burned up.

2 Ground resolution is a useful but simplistic measure of the capability to identify

objects from high altitude.

81
82 I Remote Sensing From Space

Figure 6-l—Bomb Damage Assessment of Baghdad During the Persian Gulf Conflict

Although these SPOT images of downtown Baghdad, Iraq, have sufficient ground resolution (10 m) to distinguish intact bridges

(left) from damaged ones (right), SPOT’s usual timeliness would be inadequate for many bomb damage assessment tasks.

SOURCE: Copyright 1993, CNES. Provided by SPOT Image Corp., Reston, VA.

ian satellite systems. Landsat satellites pass over

any given place along the equator once every 16

days; SPOT passes over once every 26 days. In

addition, both systems may take weeks to process

orders and military data users generally require

much shorter response times. Because civilian

missions generally have less stringent requirements than military ones, civilian satellite systems will continue to fall short in this regard

unless they begin to cater expressly to the military

market or improve revisit time for other reasons,

such as crop monitoring or disaster tracking. As

noted in chapter 4, one way to increase timeliness

without adding additional satellites is to provide

sensors with the capability of pointing to the side.

SPOT has the capacity for cross-track imaging,

and can reimage targets of interest in 1 to 4 days.

. Arms Control—Civilian satellite data have

limited, but important utility for supporting arms control agreements. Although

some facilities have been imaged by civilian

satellites, many other arms-control tasks are

beyond the capabilities (particularly resolution) of civilian satellites. Their greatest

weakness in most military applicationslack of timely response-is of less concern

in the arms control arena, where events are

typically paced by diplomatic, not military,

maneuvers.

Mapping—Mapping, including precise measurement of the geoid3 itself, is a civilian

mission with important military applications. These include simulation, training,

and the guidance of automated weapons.

Existing civilian satellite data are not adequate to create maps with the coverage or

precision desired for military use. The military use of data from civilian land remote

sensing satellites would be greatly enhanced by improved resolution, true stereo capabilities, and improved orbital

location and attitude of the satellite. Military map makers and planners would also

find use for data acquired with a civilian

synthetic aperture radar system, which

can sense Earth’s surface through layers

of clouds.

3 The figure of the solid Earth.
—

Chapter 6–Military Uses of Civilian Remotely Sensed Data | 83

Box 6-A—The Broadening of Access to Military Information

The commercial availability of militarily useful remotely sensed imagery has sparked the interest of many

interested in military affairs. Landsat and SPOT images have appeared in the media, and have been used to

support news stories about military action or potentially threatening behavior (plate 1O).l

Individuals who have used these images to make significant deductions regarding military activity include

Johnny Skorve, whose photographic explorations of the Kola Peninsula using SPOT and Landsat images fill two

volumes; Bhupendra Jasani, who has used SPOT data of the territory of the former Soviet Union to investigate

military questions including INF Treaty compliance (plates 11 & 12), and reporters for several news organizations.

These efforts have shown that the resolution provided by SPOT and Landsat, while poor compared to the

rule-of-thumb requirements often stated for some military tasks, is more than sufficient to provide useful and even

intriguing military information.

Civilians have also explored the military use (as distinct from utility) of civilian satellites by studying the records

of SPOT Image, S.A. The corporation does not identify its customers, but its catalogue does list pictures already

taken by latitude, longitude, and date. Peter Zimmerman makes a convincing case, on this basis, that SPOT has

been used for military purposes.

These investigations of military matters share at least one trait in common: they do not require especially

timely data. As described in appendix C, it is lack of timeliness, not of resolving power, that most limits the military

use of civilian satellites.

See U.S. Congress, Office of Technology Assessment, Commercial Newgathering from Space, OTA-lSC-TM40 (Washington, DC: U.S. Government Printing Office, May 1987).

SOURCE: Office of Technology Assessment, 1993.

Because other nations control some of the are offered to all purchasers at the same price and

most capable civilian remote-imaging satellites, delivery schedule, foreign belligerents can buy

they could deny the United States access to some Landsat data to further their wars against each

imagery for political reasons, or operate their other. These data, coupled with information from

systems in ways inimical to U.S. interests. the Global Positioning System (GPS), might even

Investment in improving U.S. technical be used to prepare for a war (or terrorism) against

strength in civilian remote-imaging could allay the United States or its allies. As technical

these fears. However, attempting to stay far progress continues to improve spatial and spectral

ahead of all other countries in every remote resolution, the military utility of successive gensensing technology could be extremely expen- erations of civilian remote sensing satellites will

sive, and would therefore be difficult to sustain also improve. Although such uses of satellite

in an environment of highly constrained budg- data may pose some risk to the United States or

ets for space activities. From the national its allies, the economic and political benefits of

security perspective, staying ahead in technol- open availability of data generally outweigh

ogies of most importance to national security the risks.

interests may be enough. The wide availability of satellite imagery of

Because all countries now generally follow moderate resolution, and inexpensive computer

a nondiscriminatory data policy,4 in which data tools to analyze these images, broadens the

4 This principle was originated by the United States when it decided to seLl Landsat data on this basis. See U.S. Congress, OffIce of

Technology Assessment, Remote Sensing and the Private Sector, OTA-ISC-TM-239 (Washington, DC: U.S. Government Printing OffIce,

April 1984) for a discussion of the relationship of the U.S. nondiscrimina tory data policy to the ‘‘Open Skies’ principle.
84 | Remote Sensing From Space

number and types of institutions and individuals

with access to information about secret sites and

facilities (box 6-A). Such information contributes

to a widening of the terms of the political debate

over future military policies in the United States

and elsewhere.

Because the military value of remotely sensed

data lies in timely delivery, the United States

could cut off access to data as soon as the

countries’ belligerent status is made clear, as in

the Persian Gulf Conflict where both SPOT

Image, S. A., a French firm, and EOSAT, Inc., cut

off data to Iraq. In that case, the French were part

of the allied team opposing Iraq. However, the

United States and France (or another country that

operates a remote sensing system capable of

being used for military purposes) might be on

opposing sides of a future dispute.
T

he United States annually invests hundreds of millions

of dollars in remote sensing satellite systems and

services. Some of this investment has stimulated a

market for commercial products. Private industry contributes to U.S. satellite remote sensing systems in several ways.

Under contract to the Federal Government, private companies

build the satellites, ground stations, and distribution networks. In

the case of the Landsat system, a private firm, Earth Observation

Satellite Co. (EOSAT), markets data from Landsats 1 through 5

and will soon sell data from Landsat 6.1 In a new financial and

organizational arrangement, Orbital Sciences Corp. (OSC) plans

to launch2 and operate the SeaStar remote sensing satellite,

which will carry a sensor capable of monitoring the color of the

ocean surface. Among other ocean attributes, ocean color data

indicate ocean currents, fertile fishing grounds, and ocean health.

OSC will sell the data generated by this sensor to an assortment

of customers, including the Federal Government.3 Finally, the

remote sensing value-added sector develops useful information

from the raw data supplied by aircraft, satellite, and other

sources, and sells the resulting information to a wide variety of

users.

The value-added sector is part of a much larger information

industry that employs geographic information systems (GIS) and

other tools to turn raw data from satellites, aircraft, and other

The Role

of the

Private

Sector 7

sources into useful information. Industry products include maps;

1 Landsat 4 and 5 are currently operating. Landsat 6 will be launched in mid 1993.

q Through NASA, which is acting as an anchor tenant for the arrangement.

85
86 I Remote Sensing From Space

inventories of crops, forests, and other renewable

resources; and assessments of urban growth,

cultural resources, and nonrenewable resources.

According to market estimates, sales of data,

hardware, and software currently total about $2

billion annually.4 GIS hardware and software

have the unique advantage of being able to handle

spatial data in many different formats and to

integrate them into usable computer files. For the

next several years, at least, the private sector is

likely to derive greater profits from the provision of value-added services than from owning

and/or operating remote sensing satellites.

Private firms will also likely continue to be a

source of improved methods of accessing,

handling, and analyzing data.

Improved market prospects for the sales of land

remote sensing data will depend directly on the

continued development of faster, more capable,

and cheaper processing systems. In addition, the

continued improvement of GIS software and

hardware will make remotely sensed data accessible to a wider audience. In turn, the growth of the

GIS industry will be aided by the development of

the use of remotely sensed land data, including

the extensive archives of unenhanced Landsat

data that are maintained by the U.S. Geological

Survey Earth Resources Observation Systems

(U. S.G.S. EROS) Data Center, Sioux Falls, South

Dakota. 5 OTA will assess the prospects for

enhancing the private sector involvement in

remote sensing in two forthcoming reports.

Despite professed interest among private entrepreneurs in building and operating land remote

sensing satellites systems,6 the high systems costs

and the lack of a clearly defined market for

remotely sensed data have inhibited private offerors.

7 For example, although EOSAT has streamlined the operations and data distribution system

of Landsat, and achieved sufficient income to

continue its efforts without government support,

projected increases in revenues from data sales do

not appear sufficient to enable a system operator

to finance the construction and operation of the

Landsat system. Despite several technological

advancements since the 1970s when the National

Aeronautics and Space Administration (NASA)

launched the first Landsat satellites, Landsat

system costs have remained high. The Landsat 6

satellite cost about $320 million to build. Landsat

7, which improves on the sensors of Landsat 6,

will cost between $440 and $640 million to build,

depending on whether or not it will carry the High

Resolution MultiSpectral Stereo Imager (HRMSI)

desired by the Department of Defense (DoD) and

NASA.

Future commercialization efforts will depend

on whether firms can raise sufficient private

and/or public funding to pay for a system that is

privately developed and operated. The future

viability of a private remote sensing system

will depend on drastically reducing the costs of

a satellite system through technology development and/or dramatic market growth. It may

also rest on allowing private operators to

determine their own data pricing policies.8

Since it launched the frost civilian remote

sensing satellite in 1960, in support of the

principles of “open skies” and free flow of

information, the United States has followed a

policy of making remotely sensed data available

on a nondiscriminatory basis to potential custom4 ~ ~G1s M~ket5 and @mtunities, 1991s “ Daratech, Cambridge, MA, 1991.

S The EROS data center archive contains some 210,000 multispectral Thematic Mapper scenes gathered fmm around the globe since 1982.

6 See, for example, U.S. Congress, Office of Technology Assessment Commercial Newsgathering from Space, OZ4-TM-ISC-40

(Washington DC: U.S. Government printing Office, May 1987).

T However, private companies have invested in less costly aircraft systems. For example, Texaco, Inc. recently embarked on a rnajorprogram

to develop a multiband aircraft imaging system for environmental analyses and spill detection.

8 U.S. Congress, Office of Technology Assessment, Remotely Sen.red Data porn Space: Distribution, Pricing, and Applications

(Washington DC: Office of Technology Assessment, July 1992).
Chapter 7—The Role of the Private Sector |87

ers — in other words, on terms that are the same

to all customers.9 The Land Remote Sensing

Policy Act of 1992 retains nondiscriminatory data

availability1o for government-supported systems,

but it gives authority to the Secretary of Commerce to license firms who wish to launch and

operate privately funded systems. These firms

may offer data on their own terms,l 1 provided

they have not received funding from the U.S.

Government to acquire their systems. In January

1993, the Department of Commerce (DOC)

granted the first commercial remote sensing

license to WorldView Imaging Corp. of Livermore, California. The license allows WorldView

to operate a pair of multispectral imaging satellites in low Earth orbit. WorldView expects to

launch its satellites, which are designed to gather

panchromatic data of 3 m resolution, in a few

years.

12 On June 10, 1993, Lockheed Corp.

announced that it filed with DOC for a license to

operate a satellite system capable of 1 m resolution (panchromatic) .13

The greatest problem private industry faces in

developing and operating a remote sensing system is the difficulty of obtainin g sufficient private

capital to finance the venture. The Federal Government is the largest customer for land remote

sensing data. If private industry were able to

count on sufficient sales of data to the government

for its needs, the financial markets might be more

willing to finance a remote sensing system.

Therefore, if Congress wishes to encourage the

development of a private satellite industry that

builds and operates remote sensing satellites, it

could direct Federal agencies to contract for

the provision of data from a privately owned

and operated satellite system, or systems,

rather than contract for the construction of a

system to be owned by the government.

Such an approach would give greater discretion

to private industry to use its innovative powers to

solve technical problems. It might also involve

greater technical and financial risk, both to the

government and to private firms, than one in

which the private sector acts solely as contractor

to the government.14 In the long run, encouraging

industry to take greater responsibility for the

provision of remotely sensed data may also lead

to wider data use, as industry would then be

encouraged to find new uses for the data. The

experiment with OSC’s SeaStar satellite system

should provide useful insights for the development of future privately owned satellite systems.

NASA contracted with OSC to provide a specified quantity of data from the SeaWiFS sensor

aboard SeaStar for a specified price. The arrangement allows NASA to provide some funding

($43.5 million) Up front that OSC has been able to

use in developing the sensor and satellite. More

important, NASA anchor tenant agreement with

OSC also allowed the company to secure needed

additional funding from the private financial

market. If this arrangement proves successful, it

might pave the way for similar agreements for

data from larger, more complicated satellites.

In addition, Congress might wish to explore

the option of funding a research program

specifically designed to reduce the costs of

remote sensing systems; cost reduction would

take precedence over providing greater capa9 U.S. Congress, ~lce of Technology Assessrnen4 Remote Sensing and the Private Sector, OTA-ISC-TM-239 (Washingto% DC: U.S.

Government Printing Of31ce, April 1984), p. 7.

10 Ibid.

11 my my, for e~ple, elat to c~ge I@CI prices for more timely detivery of dat& or, fOr m ~ditio~ f=,s~t exclusive access to

certain data for a spectiled period.

12 U.S. ~~ent of commerce News Release, Jan. 28, 1993.

13 ~ud David, ‘‘~~e~ Plans to Market Spy-Quality Imagery, ’ Space News, June 14, 1993.

14 As ~ted ealicr ~ ~~ ~eP~ system p~d for solely by tie Feder~ Govmnment, of ~Mse, ~SO SUSMiXI budge~ tWhDictd, and

progr aromatic risks.
88 I Remote Sensing From Space

bility. It might, for example, wish to fund, on a

competitive basis, the private development of

sensors and small satellite buses specifically

designed to reduce costs. Although such innovative programs involve greater risk than the usual

way government procures new technology, as the

development of amateur communications satellites has demonstrated, they also have a potentially high payoff in increased provision of

inexpensive services. 15 Among other things, an

innovative program to reduce sensor and satellite

costs, or to provide increased capability, might

introduce greater competition into the development of remote sensing satellite systems.

The government might also wish to involve the

private sector in global change research by

sharing data sets with private industry for research purposes. In a 1992 report, the Geosat

Committee pointed out that the oil, gas, and

mineral extraction industry is heavily involved in

performing research on the environment in connection with its profit-making interests. The

Geosat Committee proposed to institute pilot

programs that would involve both private industry and the government in a research partnership,

in which the government could gain useful global

change information, and private industry would

gain access to a wide variety of data to support its

research interests. 16 Such research programs, in

which the government and the private sector join

forces in partnership, could enhance the significance of remotely sensed data for global change

and even lead to innovative new methods for

using them.

15 ~tew~dio ~Pmtors ~ve b~t ~d ~~ched seve~ ~1, low-cost, low-orbit communications satellites. See U.S. Congress, OfflCe

of Technology Assemnen4 Aflorduble Spacecraji: Design and Luunch Alternatives, OTA-TM-ISC-60 (Washington DC: U.S. Government

Printing Offke, September 1990), pp. 19-20.

16 me -Sat Committee, ~c., ‘‘Applying Resource Industry’s Research to the U.S. Global Change Research Program,’ No- OK,

1992.
International

Cooperation

and

Competition 8

T

he European Space Agency (ESA) and the governments

of China, France, India, Japan, and Russia each operate

remote sensing systems to study Earth’s surface. 1

Canada will join this group in 1995 when it launches

Radarsat, a system optimized to monitor ice conditions, especially in the northern hemisphere. Europe, Japan, and Russia

operate satellite systems designed to gather weather and climate

data. In many cases, data from these systems complement U.S.

data. In others, they overlap them. The many non-U.S. remote

sensing systems either planned or in operation raise concerns of

competition and cooperation for the United States. Until

recently, the United States led the world in all areas of remote

sensing from space. Now other countries compete with the

United States for the small but growing commercial market in

remotely sensed data. For example, SPOT Image, S.A., has been

selling data from the French SPOT satellite since 1987. Other

countries also compete with the United States for scientific and

technological kudos.

INCREASED INTERNATIONAL COOPERATION IN EARTH

MONITORING AND GLOBAL CHANGE RESEARCH

The experience of Canada, ESA, France, Japan, and Russia

with remote sensing technology and data handling suggests that

they would make effective partners in cooperative satellite and

data programs. Indeed, as noted earlier in this report, the United

States plays an active part in cooperative activities to gather and

distribute meteorological data (box 8-A). It also cooperates

I I

89
90 I Remote Sensing From Space

Box 8-A-international Cooperation in Weather Monitoring

International cooperation in meteorological satellites has a long, successful history.1 The U.N. World

Meteorological Organization (WMO), founded in 1951, can trace its roots to the International Meteorological

Organization, which was established in 1853. The WMO is a planning and coordinating body with basic programs

to help all countries cooperatively produce and obtain important meteorological data.

Extensive cooperation is evident between the United States and many European countries. As noted, the

United States has excellent working relations with Eumetsat and now relies on a Eumetsat weather satellite to

augment coverage of the remaining geostationary operational environmental satellites (GOES) platform; the

United States had previously made excess GOES weather monitoring capability available to Europe.

Although international cooperation can reduce costs to each party, there are limits on the extent of

cooperation that infeasible. For example, weather patterns and the nature of severe storms in the United States

are different than those of Europe. In the future, U.S. meteorologists are interested in obtaining simultaneous

images and soundings, a capability that will provide better warning of relatively small, violent storms, such as

tornados. Because the conditions that might produce small, extremely severe storms are very seldom present in

Europe, Eumetsat accords lower priority to simultaneous imaging and sounding in its geostationary satellite

system.

1 See appendix D for a more detailed description of international oooperatfon in weather monitoring and other

remote sensing activities.

extensively with Europe on the National Oceanic planned satellite Earth observations,3 and in the

and Atmospheric Administration’s (NOAA) polar

orbiting satellite system, and both Europe and

Japan have important roles in National Aeronautics and Space Administration’s (NASA) Earth

Observing System (EOS) program. In addition,

the United States has worked closely with Canada

on the development of Radarsat. NOAA and

NASA have sought cooperative arrangements in

order to reduce their program costs, but also to tap

the considerable scientific and engineering expertise available in Japan and Europe. U.S. partners

have similar motivations with respect to the

United States.

The United States participates in the Committee on Earth Observation Systems (CEOS), created in 1984,2 which coordinates existing and

International Earth Observing System (IEOS),

which NASA organized to coordinate the work of

the international partners in EOS. In other words,

these cooperative arrangements provide benefits

consistent with U.S. space policy:

The United States will conduct international

cooperative space-related activities that are expected to achieve sufficient scientific, political,

economic, or national security benefits for the

nation. 4

The success of these cooperative efforts and the

desire to make greater use of shared scientific and

technical resources, combined with the need to

find more efficient, cost-effective ways of gathering global environmental data have led to numerZ CEOS developed out of discussions begun in 1982 at the June meeting of the Economic S ummit of Industrialized Nations in which a

working Oroup on Technology, Growth and Employment discussed cooperative efforts in satellite remote sensing. An international Panel of

Experts on Remote Sensing from Space, chaired by the United States, established CEOS in 1984,

s D. Brent Smit.iL “International Coordination of Earth Observation From Space Activities. ’ Paper presented at the Twenty-’l’hird

International Symposium on Remote Sensing of Environment, Bangko& Thailand, Apr. 18-25, 1990.

4 The White House, National Space Policy, Nov. 2, 1989, p. 2.
Chapter 8-international Cooperation and Competition |91

ous suggestions for closer international cooperation in environmental remote sensing.s Such

suggestions are consonant with more general

interest in enhanced international cooperation.

The end of the Cold War and the continued

growth of scientific and technical competence

overseas makes such cooperative arrangements

much more feasible than before. Indeed, several

recent reports have urged greater international

cooperation in space activities than previously

experienced.6 However, the perceptions, habits,

and institutions developed by the world during

the height of the Cold War will not change

quickly. In addition, as several recent reports of

the Carnegie Commission on Science, Technology, and Government have noted, U.S. science

and technology institutions need to be improved

in order to foster more effective international

collaboration. 7

INTERNATIONAL COOPERATION AND

SURFACE REMOTE SENSING

Several authors have suggested that the United

States should approach other countries about

establishing a cooperative program in surface

remote sensing.8 Because both commercial considerations and government prestige and control

are involved in the provision of remotely sensed

surface data, the issue of cooperation is more

complicated than with strictly governmentgovernment cooperative arrangements, or with

strictly commercial cooperative ventures. On the

one hand, satellite system costs often exceed

one-half billion dollars for a single satellite and

its associated ground systems.9 On the other, the

existence of several systems, each generating data

of somewhat different characteristics and quality,

gives data purchasers a greater variety of data

sources from which to choose. Yet, as a result of

the high system and operations costs, data prices

remain high even though they are still highly

subsidized. In order to limit unnecessary redundancy by governments, reduce costs, and

to promote more effective application of the

data for a wide variety of data users, the United

States may wish to explore the potential for

working with other countries in a cooperative

venture in surface remote sensing.

The existing governmental and commercial

structures for multispectral land remote sensing

provide a specific example of how difficult such

cooperation might be to arrange. For example, the

French firm SPOT Image, S.A. sells data from the

French SPOT satellite in competition with the

U.S. company Earth Observation Satellite Co.

(EOSAT), which markets data from the U.S.

Landsat satellite. In both cases, the governments

5 John H. McElroy, “Intelsat, Inmar sat and CEOS: Is Envirosat Next?” Presented at the American Institute for Aeronautics and

Astronautics Workshop on International Space Cooperation: barring from the Past Planning for the Future, Hawaii, December 1992; D. Brent

SmitlL Linda V. Moodie, Betty A. Howard, Lisa R. Schaffer, and Peter Backlund, “Coordinating Earth Obsemations from Space: l’bward a

Global Earth Observing System” (IAF-9(L1OO). Presented at the 41st Congress of the International As@omutical Federation October 1990,

Dresden.

b U.S.-Crest, Partners in Space (Arlingtom VA: U. S.-Cres4 May 1993); Vice President’s Space Policy Advisory Board, A Post Cold War

Assessment of U.S. Space Policy (Washington DC: The White House, December 1992), pp. 33-38; Space Policy Institute and Association of

Space Explorers, “International Cooperation in Space-New Opportunities, New Approaches: An Assessment,” Space PoZicy, vol. 8, No. 3,

August 1992, pp. 195-204.

7 Carnegie Commission on Science Technology, and Government Science and Technology in U.S. International Affairs (New York NY:

Carnegie Commission January 1992); Carnegie Commission on Science Technology, and Government ZnternationalEnvironmental Research

andDevelopment Research andAsses$ment: Proposals forgetter Organizan”on andDecision Making @Jew York NY: Carnegie Commissio%

July 1992).

8 Neil R. Helm and Burton 1. Edelsou ‘‘An Internation.rd Organization for Remote Sensing’ (IAF-91-1 12). Paper presented at the 42nd

Congress of the International Astronautical Federation October 1991, Montreal, Canac@ John L. McLucas and Paul M. Maughan, ‘ ‘The Case

for EnvirosaC” Space Policy, vol. 4, No. 3, August 1988, pp. 229-239.

9 DOD and NASA ~~ate ~t for ~dsat 7, a~isition ad operatiom costs over 5 y~s of operation will toti over a bitlion dolhirs.

See ch. 4.
92 | Remote Sensing From Space

paid for and launched the satellites. Until the

Russian Almaz satellite, which carried a synthetic

aperture radar (SAR), failed in October 1992, a

Russian government corporation was marketing

data from the government-owned and operated

satellite.l0”

Such a cooperative venture might be tried with

a system for which the commercial data markets

are less well developed. For example, the United

States could seek to institute a cooperative

development program for a SAR system, to be

used not only for global change research, but also

for supporting development and resource management projects, and for a wide variety of

commercial uses. The U.S. SAR, which NASA

had planned to build as part of its EOS, would

have been a highly sophisticated and expensive,

multifrequency, multipolarization system.11 Because of the cost and technical risk involved,

NASA deferred development of its EOS SAR.

However, because several other countries also

have experience in building SAR instruments, it

might be possible to construct an effective

multifrequency, multipolarization SAR system in

partnership with other countries. One way to do

this and keep the technical and managerial

interfaces relatively uncomplicated would be for

each organization involved to build its own SAR

satellite designed to operate at a frequency

different from the others. 12 Each satelleite could

also be designed to operate aeat several polarizations.13 If flown in adjacent orbits, these satellites

would operate much like a multifrequency, multipolarization SAR on a single platform, but the

cost and technical risk of each satellite would be

less than for the single platform.

Under this arrangement, partners from different countries or space organizations could each

contribute different space instruments, satellite

platforms, or receiving systems in return for

favorable data prices. Each partner could still

develop expertise in several different areas, cooperating where expertise did not overlap, competing where it did. Because the scale of the

investment would be so large as to require major

funding from governments, who would also be

the venture’s primary customers, it might be

possible to structure the project initially under the

aegis of CEOS. If the system were technically

successful, it might eventually be advantageous

to house it in a more permanent administrative

structure. 14

MAINTAINING A U.S. COMPETITIVE

POSITION IN REMOTE SENSING

The U.S. desire to maintain a strong U.S.

position in high technology products in order to

contribute to its economic competitiveness and

reach a more favorable balance of international

trade raises the question of how the United States

can bolster its technological advantage and improve its competitive market position in remote

sensing technology and data products. Especially

with the projected reductions in spending for

defense-related technologies, the United States is

disadvantaged abroad by its existing policies of

generally maintaining an arms-length relationship between the government and private indus10 Witiaresolution as fme as 7 meters, this satellite was a powerful tool forgeneratingmaps of the Earth’s surface and for ob=wm c-es,

despite intervening cloud cover. In the United States, Almaz data were distributedf~t by Space Commerce Corp., and morerecentiy by Hughes

STX Corp. For a variety of reasons, including uncertain data delivery, sales have been limited.

11 NASA es~tes place the cows of the NASA plan at about $1.5 billion. See app. B for a detailed description of SAR t=kology.

12 ~L s~ pro- offlci~s, who originated ~s con~pt, sugg~t tittie bands wo~d IX appropriate--C band, L ban~ and X band.

‘3 Different pola.rizations provide different views of Earth’s surface, depending on the material sensed. Multiple polarizations on the same

instrument provide substantial additional data for analyzing surface conditions.

14 McE~oy, op. cit., footnote 5.
Chapter 8–international Cooperation and Competition | 93

try. Other countries, most notably Canada and

France,15 have aggressively pursued the development of remote sensing satellite systems to

monitor the land surface and oceans in concert

with their private sector.l6

In order to maintain and enhance U.S.

capabilities in civilian remote sensing, the

United States may need to develop new forms

of partnership between government and the

private sector. Otherwise, the United States

could be left behind in the race to develop new

remote sensing technologies. In particular, the

previous chapter suggested that the U.S. government could undertake R&D programs to foster

innovation in the development of sensors and

satellite systems within the U.S. private sector

and move toward purchases of data rather than

satellite systems from the private sector.

The final report of this assessment will examine the benefits and drawbacks of international

cooperative mechanisms in much more detail in

the context of a strategic plan for U.S. remote

sensing activities. In particular, it will explore

issues such as:

. institutional models for international cooperation in remote sensing;

● the roles of U.S. agencies, including NASA,

NOAA, Department of Defense, and the

Department of State;

. the United States as a cooperative partner:

successes and failures; and

. the appropriate balance between cooperative

and competitive activities.

15 R~~~ ~s ~so develop~ private companies to market Emotely *A ~@ wi~ ‘id ‘Salts

16 ~m it ~On~~ted Wltb E_jsA’r t. ~J@&@ from me ~n&t series of m~~ites, tie unit~ Stites ~SO developed a new publicJpnvate

institution. However, ambivalence within the U.S. Government toward the arrangement made it extremely difficult to follow through with the

arrangement.


PLATE 4

180

PLATE 8



Appendix A:

Research and

The Earth

Observing

u

ntil recently, meteorological applications were the primary

force behind the development of civilian remote sensing

systems. In the future, meteorology and global change research

will influence the direction of remote sensing developments.

Widespread attention to scientific issues regarding global change is

likely to result in spending several billion dollars for sensor and

spacecraft development. This appendix evaluates the relationship

between planned sensors and the study of climate and environment, and

reviews sensor development plans in detail,

Future remote sensing systems will provide improved recognition

and understanding of environmental problems, and collect data to

inform scientists and policymakers of the ramifications of a changing

environment. 1 Future systems (such as EOS) are designed to provide a

better understanding of the processes affected by changes in the

atmosphere. 2 More complete data from remote sensing satellites,

combined with increased opportunities to test models against reality,

can improve environmental models, especially general circulation

models (GCMS) of global climate.3

Remote sensing from space provides an effective way to determine

the extent of environmental change. Space-based remote sensors are

capable of yielding the synoptic view of global events necessary to

identify and quantify changes occurring in the atmosphere and on the

I In addition to helping to answer questions about whether the Climate is changing,

remote sensing systems are regularly used to monitor ecosystems, map wetlands, and

track pollution.

2 NASA’s EOS program is being designed to address many of the key areas of

scientific uncertainty. See the National Research Council, The U.S. Global Change

Research Program, An Assessment of FY 1991 Plans, National Academy Press, 1990.

Although EOS has been restructured since this evaluation was written most of the

instruments evaluated by the study are still included in EOS.

J Effectiveness of the data from any observation system in explaining observed

phenomem is determined by the way data are used.

95
96 I Remote Sensing From Space

Box A-1-Climate Change

Many oft he remote sensing systems discussed in this report are designed to provide data about the climate.

The Earth’s climate is determined by many factors. The primary force is radiant energy from the Sun, and the

reflection or absorption and reradiation of this energy by atmospheric gas molecules, clouds, and the surface of

the Earth itself (including forests, mountains, ice sheets, and urban areas). A portion of the reradiated energy

leaves the atmosphere. Over the long term, balance is maintained between the solar energy entering the

atmosphere and energy leaving it. Within this balance, interactions among the atmosphere, snow and ice, oceans,

biomass, and land cause variations in global and local climate. For example, El Nino, the large-scale warming of

the tropical Pacific that occurs periodically, is apparently the result of complex interactions between the ocean and

atmosphere.’

A region’s general climate is defined by aggregate weather patterns-for example, snowfall, predominant

wind direction, summertime high temperature, precipitation-averaged over several decades or longer. These

patterns can vary substantially from one year to another in a given area. The mean annual temperature of the

United States, for example, can differ by O.5 to 1.5 0C. When scientists discuss climate change, they are generally

referring to trends that persist for decades or even centuries, over and above natural seasonal and annual

fluctuations. One type of change arises from forces that are external to the Earth’s climate system. The ice ages

and glacial-interglacial cycles, for example, are thought to have been triggered by changes in the seasonal and

geographical distributions of solar energy entering the Earth’s atmosphere associated with asymmetries in the

Earth’s orbit around the Sun. Also, major volcanic eruptions can deposit aerosols (e.g., sulfate particles) into the

stratosphere, partially blocking or screening sunlight from reaching the surface of the Earth and thus temporarily

cooling the Earth’s surface. Variations in volcanic activity (1992 was cooler than normal in many parts of North

America, in all likelihood because of the eruptions of Mt. Pinatubo), ice sheets, forest cover, marine phytoplankton

populations, and/or ocean circulation, among other factors, may have interacted with solar variability (including

changes in the Sun’s brightness) to determine the Earth’s past temperature record.2

Other changes to the climate can be linked to human activity. Fossil fuel emissions and the release of

compounds such as chlorofluorocarbons have changed the makeup of the atmosphere. To what extent human

activity has contributed to changes in atmosphere and how these changes affect the climate is not clear.

1 G.A. Meehl, “~asonal cycle Forcing of El Nifk+!%wthern W“llation in a Global Coupled Ocean-Atmosphere

GCM,” JoumalofChnate 3:72-98, 1990.

2 we S. Ba[iunas, and R, Jastrow, “Evidence for Long-Twin Brightness Changes of Solar-Type StarS,” Ni+ttWO

348:520-522, 1990; W.S. Broecker, “Unpleasant Surprises in the Greenhouse?” Nature 328:123-126, 1987; R.A. Bryson,

“Late Quarternary Volcanic Modulation of Milankovitch Climate Forcing,” 77woretical and Applied Climatology

39:115125, 1989,

SOURCE: Adapted From U.S. Congress, Office of Technology Assessment, Changing by Degrees: Steps to Reduce Greenhouse Gases,

OTA-O-4S2 (Washington, DC: U.S. Government Printing Offioe, February 1991).

surface. Global viewing is critical to understanding | Remote Sensing and the Current State of

geophysical processes, since many seemingly isolated Climate Research

events are parts of a whole. As a result of growing Is there evidence of climate change (box A-l)? What

catalogues of data, better quantitative models that are the implications of variations in temperature,

simultaneously consider ocean and atmosphere have rainfall, cloud cover, polar ice and sea level? These

grown in sophistication.4

questions spark controversy among climatologists,

biologists, economists, and politicians. Differences in

4 Thomas F. Malone, “Mission to Planet Earth+” Environment, vol. 28, October 1986, p.6.
Appendix A—Research and the Earth Observing System |97

opinion often derive from large uncertainties in data,

imperfect numerical models, and assumptions that

drive predictive models. For example, climate data

show evidence of a slow but steady increase in global

temperature, and glacial records indicate higher levels

of CO2 and other gases than at any other time since the

ice age, Yet future trends and consequences of

continued climate and environmental change are

highly uncertain. Remote sensing systems are essential

if researchers are to assemble a comprehensive picture

of global processes.

The study of global change, much like the study of

meteorology, encompasses the effects of many earth

processes.

5 Scientific uncertainty manifests itself as

wide variations in general circulation models used to

predict climate change and understand the human

impact on the environment. Key elements of uncertainty in developing predictive models include:

●

●

●

●

clouds, primarily cloud formation, dissipation,

and radiative properties, which influence the

response of the atmosphere to greenhouse forcing;

oceans, the exchange of energy between the

ocean and the atmosphere, between the upper

layers of the ocean and the deep ocean, and

transport within the ocean, all of which control

the rate of global change and the patterns of

regional change;

greenhouse gases, quantification of the uptake

and release of the greenhouse gases, their chemical reactions in the atmosphere, and how these

may be influenced by climate change; and

polar ice sheets, which affect sea level rise.6

General circulation models are complex computer

models of the climate system that quantify the

interaction of various elements of the environment,

allowing researchers to develop hypotheses regarding

the climate and elements of change. Uncertainties in

GCMS can be reduced in two ways: first, improve the

data used in GCMS; second, rigorously test predicted

results against real events to improve the models

themselves.

Plans for future remote sensing satellite systems call

for the development of a number of sensors to obtain

data that will improve scientists’ understanding of

clouds, oceans, and atmosphere. These data, which

will be used in GCMS and other models, should

improve the ability of scientists to understand the

interaction of systems and reduce some of the current

uncertainty. 7

Uncertainties regarding climate change abound, yet

substantial evidence exists that environmental change

has already taken place. According to many climatologists, human activity is altering the climate system

beyond the limits of natural rates of change experienced by the Earth over the last hundreds of thousands

of years.8 Human activity is dramatically changing the

chemical makeup of the Earth’s atmosphere. Atmospheric concentrations of several “greenhouse gases, ’

which trap heat in the atmosphere, naturally keeping

the earth at a habitable temperature, have risen rapidly

over the last 100 years, (box A-2) and according to

some, have contributed to increased average temperatures. 9 Most of these gases (carbon dioxide, methane,

and nitrous oxide) occur naturally, but their rapid

increase results mainly from human activity. For

example, the atmospheric concentration of carbon

dioxide is currently increasing about 30 to 100 times

faster than the rate of natural fluctuations found in ice

s Ibid, p. 6.

6 Intergovernmental Panel on Climate Change, Scienfifi”c Assewnent of C/imute Change, World Meteorological OrganizMion, 1990, p. xxxi.

7 Data detailing changes in land surface hydrology, solar radiation cycle, characteristics of surface albedo, the role of atmospheric and surface

winds, amount and health of biomass, and changes in land features will also play a large role in understanding climate and environmental

change.

g R.A. Bemer, ‘ ‘Atmospheric Carbon Dioxide Levels Over Phanerozoic Time, ’ Science 249: 1382-1386, 1990; IPCC, op. cit.; C. Lorius,

et al., “The Ice-Core Record: Climate Sensitivity and Future Greenhouse Warming, ” Nature 347: 139-145, 1990.

9 According to climate models in use today, increases of 0.3 to 1.1 C should have occurred over the past 100 years as a result of increased

atmospheric concentrations of greenhouse gases. Naturat climate variability and other factors (measurement errors, urban heat island effmts,

etc. ) confound detection of almost any climate trends, however. The Intergovernmental Panel on Climate Change, or IPCC-a group of several

hundred scientists from 25 countries, described below-concluded that the global temperature record over this period indicates that the Earth

actually has warmed by about 0.45 C, which is within the range of estimates. Yet the findings of the WCC, while representing the views of

many atmospheric scientists, are not universally accepted.
98 I Remote Sensing From Space

Box A-2-Global Warming and the Greenhouse Effect

Emissions of greenhouse gases constitute a new force for climate research (in addition to the natural climatic

phenomena). Because of natural variability in climate, the IPCC concluded that the observed 20th-century

warming trend would have to continue for one to two more decades before it can be unambiguously attributed to

enhanced greenhouse gases.’

About 30 percent of the solar radiation reaching the Earth is reflected by the atmosphere and Earth back to

space, and the remainder is absorbed by the atmosphere, ice, oceans, land, and biomass of Earth. The Earth then

emits long-wave radiation in the infrared and microwave wavelengths, which is partially absorbed and ‘trapped”

by atmospheric gases.2 The result of these natural processes is the “greenhouse” effect- warming of the Earth’s

atmosphere and surface. Without the natural heat trap of these atmospheric gases, Earth’s surface temperatures

would be about 33 0C (60 oF) coder than present.3 Human activities during the last century have resulted in

substantial increases in the atmospheric concentrations of C02, CH4, and N20.4As concentrations of these gases

increase, more radiation should be trapped to warm the Earth’s surface and atmosphere. However, as more heat

is trapped and the Earth and atmosphere warm, more thermal radiation should be emitted back to space,

eventually restoring the energy balance or equilibrium, but leaving a warmer climate.5

The basic “heat trapping” property of greenhouse gases is essentially undisputed. However, considerable

scientific uncertainty remains about how and when Earth’s climate will respond to enhanced greenhouse gases.

The more uncertain aspects of climate response include: climate feedbacks that will help determine the ultimate

magnitude of temperature change (i.e., “equilibrium” warming); the role of the oceans in setting the pace of

warming; and other climate changes that might accompany warming and how specific regions of the world might

be affected. Planned remote sensing systems such as the Earth Observing System platforms will carry sensors

that will measure these aspects of climate variability.

Predictions of future warming are highly uncertain, because of the inaccuracies of climate models themselves

and varying projections for future greenhouse gas emissions levels. Future emissions will be tied to population

and economic growth, technological developments, and government policies, all of which are difficult to project.

To avoid the pitfalls and complexity of estimating future emissions, and to provide a common basis for

comparing different models or assumptions, climate modelers typically examine climates associated with

preindustrial levels of atmospheric C02 concentration. These are compared to “equilibrium” climate- i.e., when

1 i~ergovernmenta[ panel on G~~l chan~, ~ent/f/c AWSment of Cllmate Change, Vkdd Meteorological

Organization, 19900

2 ~e: DiMn~n, R,E, and R,J. Cicerone, “Future Global Warming From Atmospheric Tram Gas8s,” ~afure

319:109-115, 1936; Lindzen, R. S., “Some Coolness Concerning Global Warming,” Bu//et/n of the Amedcan

hfeteorologkalS ociety71 :288-290, 1990.

3 At ~ OF (33 oC) ~~rt~n at pre~nt, life ~ we IUIOW it ttiy on Earth would not be Posstble. Water vapor (in

the form of clouds) and carbon dioxide (COJ are the major contributors to this effect with smaller but still significant

mntn%utbns from other trace gases, such as methane (CH~, nitrous oxide (N20), and ozone (OS).

4 one must atso consider the introduction and rapid increase of the synthetic chloroflwr~rbons (CFCS), which

contribute to the destruction of atmospheric ozone (03), which absorbs in~ing ultm~~et mdiation >320 nm. ~thout

this “filter,” we will see an increase in Illness and habitat destruction due to ultraviolet energy.

5 The un~rt~nty of warming forecasts Is twofold: how much warming will occur; and what happens after small

amounts of warming? The first is self-explanatory, the second a captivating soientlfic debate. M/Ill Increased temperatures

cause more suspended water vapor (clouds) reflecting more energy and restoring current tenpratures? Wiil severe

storms become more common?
Appendix A–Research and the Earth Observing System |99

the climate system has fully responded and is in equilibrium with a given level of radiative forcing6 associated with

double those levels. Although such “sensitivity analyses” provide useful benchmarks, they are unrealistic in that

they instantaneously double COZ concentrations, rather than increase them gradually overtime. In the last few

years, scientists have intensified research using more realistic “transient” climate models where C02 increases

incrementally over time.7

Many models indicate that a range of 1.5 to 4.5 OC (3 to 8 oF) bounds the anticipated equilibrium warming,

likely in response to a doubling of Co2 from preindustrial levels.8 Uncertainty about the actual figure is primarily

due to uncertainty about feedbacks-processes that occur in response to initial warming and act either to amplify

or dampen the ultimate equilibrium response. The lower end of the range (1.5 OC change) roughly corresponds

to the direct impact of heat trapping associated with doubled C02

, with Iittle amplification from feedbacks. The

upper end of the range (4.5 ‘C) accounts for feedback processes that roughly triple the direct heat-trapping effect.

Hypothesized feedbacks that could release extra CHd and C02 into the atmosphere are not included in present

models, g so warming could be even more severe. On the other hand, clouds may block much more solar radiation

than models presently assume and thereby reduce the warming.

A 1.5 to 4.5 ‘C warming bounds model predictions of warming in response to this reference or benchmark

COZ level. Higher or lower COP concentrations (or a combination of greenhouse gas levels) might lead to greater

or less warming. The I PCC “business as usual” emissions scenario projects a global mean temperature increase

above today’s level of about .25‘C (0.54 oF) per decade, or an increase of roughly 1.0‘C (2.2 ‘F) by 2030 and

3.1 “C (6.6 “F) by 2100.

6 Change in temperature or climate caused by changes in solar radiation levels.

7 IpCC; Washington, WM. and G.A. Meehl, “Climate Sensitivity Due to Increased C02: Expedients ~th A

Coupled Atmosphere and Ocean General Circulation Model,” C/hnate DyrMmics4:l- 38, 1989.

8 lpcc; Stouffer, R-J,, S. Mana~, andJ. Bryan, ‘ClntefiemiS@eriCAS~metry in climate Resportse toa Gradual

Increase of Atmospheric Carbon Dioxide,” Nature342:660-662, 1989; J. Hansen et al., “Global Climate Changes as

Forecast by the Goddard institute for Space Studies Three-Dimensional Model,” J. Geophysica/l?eseamh, 93:9341 -9364,

1988.

9 IpCC; ~shof, D,, “The Dynamic Greenhouse: Feedback Processes that May lnfluenc8 Future Concentrations

of Atmospheric Trace Gases and Climatic Change,” Climatic Change 14:213-242, 1989.

SOURCE: Adapted from U.S. Congress, Offiea of Technology Assessment, Changing by Degrees: Steps to Reduce Greenhouse Gases

(Washington, DC: U.S. Government Printing Office, February 1991).

core samples; 10 concentrations are already 25 percent Climate models attempt to explain and predict how

above average interglacial levels and 75 percent above climate varies. The best current models predict global

the level during the last glacial maximum.11 Likewise, average surface temperatures will increase 0.5 to 2 ‘C

the atmospheric concentration of methane is increasing by 2030. However, these models have large uncertainmore than 400 times faster than natural rates of ties. They also provide widely varying estimates of the

variability y. 12 geographic distribution and consequences of change.13

No existing model is complete. 14 Taken together,

10 Lorius, et aI., op. cit.; J.M, E3arnola, et d., ‘

; Vostok Ice Core Provides 160,(Kl@Year Record of Atmospheric C02, ” Nurure 329:408-414,

1987.

11 IPCC, Sclentifi”c Assessment of Climate Change, op. cit., foomote 6.

12 J, ~ppellez et ‘.! “Ice-Core Record of Atmospheric Methane Over the Past 160,000 Years,” Nature 345: 127-131, 1990.

IS us, Env~onmen@ ~otection Agency, me Potential Eff&ts of Glob~ climate change on the United States, December 1989.

14 See Peter H. Stone, “Forecast Cloudy: The Limits of Global Warmin g Models,” Technology Review, February/March 1992, pp. 32-40;

Bette Hilernan, ‘‘Web of Interactions Makes it Difficult to Untangle Global Warming Data, “ Chemical and Engineenng News, Apr. 27, 1992,

pp. 7-19.
100 I Remote Sensing From Space

existing models provide a range of predictions regarding future climate. After reviewing numerous models,

the IPCC has concluded that if present emission trends

continue, global average temperatures could rise by

roughly an additional 1.0 ‘C by the year 2030.

If the climate were to change drastically, the effects

would not be felt uniformly. Regional changes are

extremely hard to predict because of constantly

changing atmospheric and oceanic circulation patterns. Greater warming is likely to occur in some areas;

negligible change or cooling is expected in others.

Some regions may experience more drought, others

more precipitation and perhaps changes in the frequency and intensity of storms.15

The significance of climate change predictions is not

clear. Although the evidence that human activity is

largely responsible for a changing climate is not

beyond dispute,l6 data collected over the past century

justify concern over climate. Reasons for concern

include hypotheses that climate change could:

1.

2.

3.

4.

5.

6.

7.

8.

9.

rapidly shift climate zones, preventing the

adaptive migration of animals and plants;

speed the extinction of many species;

diminish water quality (a result of algal blooms

in warmer water) in many freshwater lakes and

rivers;

raise sea level, effectively reducing the amount

of beaches and coastal wetlands;

reduce agricultural yields, possibly increase

others, but change the distribution of crops;

increase the ranges of agricultural pests;

increase the demand for electricity;

diminish air quality (increased emissions from

electric plants, speed atmospheric chemical

reactions that produce atmospheric 03);

change morbidity patterns, decrease winter

mortality, increase summer mortality;

10. change infrastructure needs of many cities;

11. diminish freshwater resources in many regions. 17

Since mitigating human impact on the environment

is expensive and risky, economic uncertainty is often

used to justify the expense of developing new remote

sensing systems. The benefits derived from increased

knowledge of the effects of global change could far

outweigh the average yearly costs for space-based

global change research (about $1 billion annually).

CURRENT ENVIRONMENTAL AND CLIMATE

RESEARCH EFFORTS

Increased data on climate change and heightened

international concern convinced the U.S. government

of the need to address global change. In 1989, the

Director of the Office of Science and Technology

Policy, D. Allan Bromley, established an inter-agency

U.S. Global Change Research Program (USGCRP)

under the Committee on Earth and Environmental

Sciences (in OSTP).18 Established as a Presidential

initiative in the FY 1990 budget, the goal of the

program is to develop sound national and international

policies related to global environmental issues. The

USGCRP has seven main science elements:

1.

2.

3.

4.

5.

6.

7.

climate and hydrodynamic systems,

biogeochemical dynamics,

ecological systems and dynamics,

earth systems history,

human interaction,

solid earth processes, and

solar influences.

Participation in the USGCRP involves nine government agencies and other organizations. 19 This research

effort, and the efforts initiated by independent organizations (above), seek a better understanding of global

15 Much of the info~ation in t.his s~tion originally appeared in U. S. Congress, Office of Technology Assessmen~ Changing by Degrees.’

Steps @ Reduce Greenhouse Gases, OTA-O-482 (Washingto~ DC: U.S. Government Printing Office, February 1991).

lb See Richard S. Lindzen, ‘‘Global Warming, The Origin and Nature of the Alleged Scientific Consensus, ” Regulation, The Cato Review

of Business and Government, Spring 1992. Lindzen states, “Not only are there major reasons to believe that models are exaggerating the

response to increasing carbon dioxide, bu~ perhaps even more significantly, the models’ predictions for the past century incorrectly describe

the pattern or warming and greatty overestimate its magnitude. ’

IT U.S. Env~onmental protection Agency, The potential Effects of Global Climate Change on the United States, EPA-230-05-89-050,

December 1989.

IS For tier ~omation SIX ‘‘Our Changing planet: The FY 1992 Research PlarL’ The U.S. Globat Change Research ROWatn, A Repofl

by the Committee on Earth and Environmental Sciences, a supplement to the U.S. President’s Fiscal Year 1992 Budget.

19 Including the Smithsonian Institution and the Tenne-see Valley AUthOritY.
Appendix A—Research and the Earth Observing System I 101

change. All will rely on remote observations of

atmosphere, oceans, and land for data.

| Mission to Planet Earth

The concept of Mission to Planet Earth evolved over

several years.20 In 1982, at a U.N. space conference

(Unispace ‘82), NASA proposed a comprehensive,

U.S.-led program to monitor the health of the Earth.

Called the Global Habitability Program, it was largely

ignored by the conference participants.21 In 1985, the

Global Habitability concept was transformed, NASA

sought to apply the concepts described by global

habitability to research focused on long-term physical,

chemical, and biological changes on a global scale.22

The research effort will rely on data collected by

ground, air, and space-based systems. NASA has

coordinated its efforts with the Committee on Earth

and Environmental Sciences, and agencies of the

Federal Government.

NASA’s stated goal for Mission to Planet Earth is to

‘‘establish the scientific basis for national and international policymaking relating to natural and human

induced changes in the global Earth system."23 The

primary program objectives include establishing an

integrated, comprehensive, and sustained program to

document the Earth system on a global scale. Mission

to Planet Earth scientists will conduct focused, exploratory studies to improve understanding of the physical,

chemical, biological and social processes that influence Earth system changes and trends on globaI and

regional scales. NASA-supported scientists will provide information for policymakers based on integrated

conceptual and predictive Earth system models.

Mission to Planet Earth will address the following

key uncertainties regarding climate change:

1. role of greenhouse gases,

2. role of clouds,

3. role of oceans,

4. role of polar ice sheets,

5. land surface hydrology, and

6. ecosystems response.

These parallel the priorities set by the Committee on

Earth and Environmental Sciences. NASA has worked

to align the instruments proposed for EOS with the

scientific and policy goals addressed by the U.S.

Global Change Research Program.

EOS AND RELATED SYSTEMS

NASA considers the Earth Observing System the

cornerstone of the Mission to Planet Earth. EOS is to

be a multiphase program that NASA expects to last

about two decades.24 The core of EOS will be three

copies of two satellites, capable of being launched by

an Atlas II-AS booster, a medium lift launcher that is

under development.

The EOS program begins with a number of ‘phase

one’ satellites (most of which predate the EOS

concept, and are funded through other programs) that

would provide observations of specific phenomena.

The Upper Atmosphere Research Satellite (UARS),

which has already provided measurements of high

levels of chlorine monoxide (C10)25 above North

America, is an example of an EOS phase one

instrument. NASA’s EOS plans also include three

smaller satellites (Chemistry, Altimeter and Aero), that

would observe specific aspects of atmospheric chemism For ~orc backwound on the genesis of Mission 10 planet m see Burton Edelson+ Science, Jan. 25, 1985, @ditorial); CRS RePOI_I to

Congress, “Mission to Planet Earth and the U.S. Global Change Research program,” Marcia S, Smith and John Justis, June 19, 1990; Sally

K. Ride, ‘ ‘Leadership and America’s future in Space, ” A Report to the NASA Administrator, August 1987. The “Ride Report, ” as this

document has become known, strongly advocates Mission to Planet Earth as a top priority for NASA’s fiNure.

‘1 See U.S. Congress, Office of Technology Assessment, UNISPACE ’82: A Context for International Cooperation and Competition,

OTA-ISC-TM-26 (Washington DC: U.S. Government Printing Office, March 1983), for more information regarding U.S. proposals and the

debate over militarization.

n Ibid.

~ presentation of Shelby Tilford, Director, NASA Earth Science and Applications Division, to the Woods Hole Space Science and

Applications Advisory Committee Planning Workshop, July 1991.

u s= Ch, 2, ch 5, and app. B for more details about NASA’S Mission to p~et~~d EOS.

25 Chlofine monoxide is a ~hemic~ compo~d ~~ when aff~ted by s~lght ~ the upper atmosphere, leads to degradation Of OS. &Qne

is formed m the stratosphere by the reaction of atomic oxygen (0) with molecular oxygen (02). This prwess is beguu by the diss~iation of

Oz into O by absorption of solar ultraviolet radiation at wavelengths below 240 nm. This process ocmrs at altitudes above 25 km. This process

can be interrupted by Cl: CI+03-+C10+C+ . . . CIOW+C1+OZ, C1O is therefore a precursor of disappearing ozone.
102 I Remote Sensing From Space

Box A-3-Measurements of Ozone Depletion

For most global change and climate change research, a combination of satellite and in situ measurements

is required to obtain sufficient data. One of the best examples of the need for both types of measurements is the

discovery of the ozone hole above Antarctica. Researchers from the United States and Great Britain had been

measuring atmospheric conditions over Antarctica: the U.S. team relying on satellite sensors; the British team

using ground-based spectrophotometers. In 1983-84, the British team recorded a series of measurements of

ozone that seemed extraordinarily low (below 200 Dobson units).1 Data from the Total Ozone Mapping

Spectrometer (TOMS) aboard Nimbus-7 and the Solar Backscatter Ultraviolet Radiometer (SBUV) aboard

polar-orbiting NOAA satellites were automatically processed by computer before being analyzed. U.S. scientists

felt that any readings below 200 Dobson units would be outside the range of possibility and were likely the result

of a sensor anomaly; hence they designed a computer algorithm that ignored such measurements. Data were

stored, and subsequently reviewed, but these readings were originally dismissed.

Neither did the British team believe its own readings. The first conclusion that project director Joe Farman

and his team reached was that their ground-based sensors, which were old, had been improperly calibrated. Yet

when anew, updated sensor produced similar results, they realized that the loss of ozone was much greater than

anyone expected. This experience demonstrates one of the advantages of ground-based sensors: sensor

packages can be easily replaced to validate the performance of the original system. It also demonstrates the

dangers of establishing a threshold for expected results.

Researchers have learned several lessons from the discovery of cyclical ozone depletion over Antarctica.

First, because ground-based sensors observe specific phenomena from a site whose environmental parameters

can be thoroughly characterized, they are sometimes more adept at detecting regional change or unusual local

environmental conditions than are satellite-based sensors. Second, although it is sometimes difficult to distinguish

between real results (signal) and invalid measurements (noise), setting predetermined limits on natural

phenomena while studying global change is not judicious. Third, even accepted models, such as the one that

provided the parameters for the U.S. research team, can be far wrong. All models should be scrutinized and

tested periodically.

1 ~Do~n unit is a measurement of thickness standardized to the thickness of the ozone Iayerat 32 degrees

Fahrenheit and sea level atmospheric pressure. One Dobson unit is equivalent to .001 cm of ozone.

SOURCE: Office of T-nology Assesamen$ 1993.

try, ocean topography, and tropospheric winds. In EOSDIS will require significant technology developaddition, NASA plans to include data from “Earth

Probes,’ additional copies of sensors that monitor

ozone and ocean productivity, in the EOS Data and

Information System. See box A-3 for a description of

ozone measurement.

The EOS Data and Information System (EOSDIS)

will be a key feature of EOS (box A-4). According to

NASA, data from the EOS satellites will be available

to a wide network of users at minimal cost through the

EOSDIS. NASA will develop EOSDIS so it can store

data and distribute them to many users simultaneously.

ment, especially in software, storage, and data processing, EOSDIS will require a continued funding effort

that will reach $254 million in 1996. In total, EOSDIS

is expected to cost $946 million between 1991 and

1997, A future OTA report will examine the data issues

related to remote sensing.

NASA plans to operate various EOS sensors for 15

years, providing researchers with data covering a

complete solarcycle26 and several El Ninos,27 two large

natural variables affecting Earth’s climate. EOS sensors will be grouped or co-located by function to

26 Appro ximately every 11 to 15 years, the Sun completes one solar cycle.

27 A ~fight ~X of the uppr wat~ of the southern pac~lc, OCCWI_@ about every 4 tO 7 ye~.
Appendix A—Research and the Earth Observing System I 103

Box A-4-The EOS Data and Information System

A central element of NASA’s Mission to Planet Earth is the EOS Data and Information System. This system

is intended to process, store, and distribute the data obtained from Mission to Planet Earth flight projects and

scientific investigations. EOSDIS is intended to be sufficiently flexible to incorporate previously archived data,

measurements from non-EOS spacecraft, and ground-, ocean-, and space-based measurements conducted by

other Federal, foreign, and international agencies. Through the EOSDIS program, NASA has promised to provide

a comprehensive system t hat will merge data from a wide variety of sources to serve integrated, interdisciplinary

research. EOSDIS is ambitious and complex; it must manage vast streams of data perhaps as many as 400 trillion

bytes per year. This is roughly equivalent to the amount of data that would fill 4 million 100-megabyte hard drives

(approximately the amount of storage purchased with a new personal computer). NASA has made comparisons

between the amount of data EOSDIS will handle and the amount of information stored in t he Library of Congress.

These comparisons are faulty, since the Library of Congress contains paintings, movies, pictures, in addition to

printed media. It is more rational to think of the amount of data to be handled in EOSDIS in terms of the largest

data bases currently on line, and no system in use to date has come close to handling this amount of data.

EOSDIS must also make these data easily usable for a very wide variety of users, possibly numbering as

many as 100,000 people, many of whom will have little detailed technical knowledge of remote sensing. EOSDIS

is intended to provide the tools needed to transform data into information, through activities such as the

development and integration of algorithms (“formulas”) for data analysis, the communication and exchange of data

among scientists, the maintenance of standards and formats for data and information, and the archiving of

scientific information for access by others.

Structurally, EOSDIS will consist of at least seven research science-oriented Distributed Active Archive

Centers (DAACS), and several Affiliated Data Centers. The seven sites selected as EOS DAACS are currently

functioning as relatively independent data centers. When linked together and integrated into EOSDIS, the DAACS

will receive raw data from EOS spacecraft and other sources, process the data, and provide data and information

to users. Three systems will operate at each DAAC:

1. a product generation system (PGS),

2. a data archive and distribution system (DADS), and

3. an information management system (lMS).

The product generation system at each DAAC will convert raw data signals into standard sets of Earth science

data, using data processing software developed by t he scientific user community. The data archive and distribution

system at each DAAC will serve as the archive and distribution mechanism for EOS data products, as well as other

data sources both within and outside the EOS program. The information management system at each DAAC will

give users access to all data throughout EOSDIS, as well as help in locating and ordering data. When fully

operational, a scientist signing onto EOSDIS at any DAAC site will have complete access to all data sets anywhere

in EOSDIS, regardless of physical location. NASA has promised to have processed data available to scientists

through EOSDIS within 4 days of initial observations.

NASA has adopted an “evolutionary” approach for the development of EOSDIS, since pre-definition of all

EOSDIS requirements is impossible (e.g., the science and data requirements for studies of the Earth system will

change as our knowledge and experience grow, and most EOSDIS users are currently not practicing Earth system

scientists; some are not yet born). EOSDIS is to have an “open” architecture, meaning that new hardware and

software technologies will be easily inserted as EOSDIS evolves, and changing user requirements can be

accommodated. Feedback from users is intended to inform each new increment of EOSDIS, a “learn-as-you-go”

approach.

(cuntkwd on naxtpage)

—
104 I Remote sensing From Space

Box A-4-The EOS Data and Information System-Continued

NASA is currently developing an early EOSDIS system (“Version O“) to improve access to existing data and

to test the interoperability of existing systems. Version O includes the development of user-friendly “pathfinder”

data sets from archived data of NOAA, DOD, and Landsat satellites, developing commonality among DAAC data

systems, and protot yping a few EOSDIS technologies. Version O is scheduled to be in place by late 1994. Versions

1 through 6 are planned to be delivered through a single contractor, Hughes Information Technology. Version 1

will provide PGS, DADS, and IMS functions at each DAAC, and examine prototyping technologies for data

processing and scheduling functions for EOS instruments. NASA plans to have Version 1 operational at all DAACS

by 1996. Version 2 will be the first full-scale operational EOSDIS, using data from the first EOS platform, and is

scheduled to be operating by the mid-1998 launch of the EOS AM1 spacecraft. Versions 3 through 6 will follow

as subsequent spacecraft are launched and science needs evolve.

SOURCE: National Aeronautics and Space Administration, General Aeeounting Office, National Researeh Counal, House of

Representatives Seienee, Space and Technology Committea

provide simultaneous coverage by complementary for all observation/monitoring projects, despite needs

instruments. Another advantage to the broad array of

sensors carried by the EOS platforms will be the ability

to isolate the effects of individual variables. A goal of

EOS is to make possible real-time analysis of these

observations.

NASA has scheduled the launch of the first EOS

satellite for 1998. Critics of EOS claim that this

schedule does not allow for timely data gathering. The

possibility exists that gaps in monitoring stratospheric

for scientific information.

EOS INSTRUMENTS

EOS Phase One-EOS Phase One is a series of

small satellites that have been grouped together under

the aegis of EOS. Most of these satellites were funded

under existing programs prior to inclusion in the EOS

program. Phase one includes the instruments below,29

which will be launched beginning in 1993.

ozone could occur in 1995-2000, especially if the

Upper Atmosphere Research Satellite (UARS, the first

●

of the EOS Phase One satellites) that concentrates on

measuring upper atmosphere ozone, fails to live past

its expected lifetime (1995). Germany had been s

planning a satellite to monitor ozone, but tight budgets

may prevent such an effort. TOMS (total ozone

mapping spectrometers) will be available on other

satellites, but may not have the ability to ‘‘record in

detail the chemical changes occurring in the stratosphere. ’28 Scientists express concern that similar gaps

will exist in other climate monitoring efforts, and will

likely arise during the lifetime of EOS. The reality of

austere budgets will affect global change research:

smaller than expected budgets will not allow funding

Sea Wide Field Sensor (SeaWiFS), an ocean color

sensor to study ocean productivity and ocean/

atmosphere interaction, still an area of climate

uncertainty.

Total Ozone Mapping Spectrometer, additional

copies of the TOMS instruments to fly on NASA

explorer class satellites and on Japan’s Advanced

Earth Observation Satellite (ADEOS). An earlier

version of TOMS had flown on Nimbus-7 in

1978, and on a (then) Soviet Meteor-3 on August

15, 1991. Japan has developed the ADEOS as an

international effort (app. D); the U.S. is providing

two of the sensors, 30 France is Providing one, 31 and

Japan will develop several others, including an

interferometric monitor for greenhouse gases and

~ C ‘Gaps ~m in Sateuite Data’ Nature, vol. 335, p. 662, Feb. 20, 1992.

29 me ~uber of p~~e oneexp~ent~ ~t~s~ive tie most rment budget cut was ~C)WII at tie time MS report went to pI_lXS. NASA

will also include data from POES, GOES, DMSP, LandSat and other satellites in the EOSDIS, hence NASA also lists data from these satellites

as phase one data.

30 me semors ~tie to~ ozone ~pp@ spectrometer (TOMS) ~d NASA Scatterometer.

31 Polariza tion and Directionality of tbe Earth’s Reflectance (POLDER).
Appendix A—Research and the Earth Observing System I 105

●

●

●

an improved limb atmospheric spectrometer.

ADEOS will be used to measure ozone and other

gases, as well as measure ocean surface winds.

The NASA Scatterometer, an instrument designed to study the ocean’s surface to determine

wind patterns and air-sea interaction, now tentatively scheduled for flight on ADEOS-11.

The Tropical Rainfall Measurement Mission

(TRMM), also a joint program with Japan, will

make extensive measurements of precipitation,

clouds and hydrology in tropical regions, which

cannot be time-sampled adequately from polar

orbit. 32

TOPEX/Poseidon, a group of sensors for measuring ocean topography and altimetry on a platform

launched by France on an Ariane booster in

August 1992.

The Upper Atmosphere Research Satellite, launched

in September 1991, became the first of these Phase

One satellites to enter service. Although its development began in 1985, UARS is viewed as the first major

project of the Mission to Planet Earth. The UARS

platform carries 10 instruments in order to meet two

project goals:

1.

2,

Observe the atmosphere over the northern hemisphere during two winters. The northern hemisphere has a greater terrain/ocean ratio, thus

providing a highly dynamic interaction between

earth, ocean and atmosphere, Although UARS

may function for over nine years, the instrument

for these observations (the Cryogenic Limb

Array Etalon Spectrometer or CLAES) requires

cryogens that will be exhausted in about 2 years.

Observe dynamic processes (presence of chlorofluorocarbons, stratospheric winds, etc.) responsible for the hole in the ozone layer above

Antarctica.33

Other instruments carried on the UARS include an

improved Stratospheric and Mesospheric Sounder

used to observe infrared molecular emissions, a

microwave limb sounder used to measure chemicals

(especially chlorine monoxide) in the upper atmosphere, a halogen occultation experiment, a wind

imaging interferometer, a solar ultraviolet spectral

irradiance monitor, a solar stellar irradiance instrument, and a particle environment monitor.34

EOS-AM

The EOS-AM satellites,35 the first of which

NASA plans to launch in June 1998, will characterize the terrestrial surface and examine the aerosol

and radiation balance within clouds. It will carry

five sensors.

1.

2.

The Clouds and Earth’s Radiant Energy System

(CERES) will provide earth scientists with

measurements of cloud and radiation flux. The

measurements will be taken with two broadband

scanning radiometers, each functioning on three

charnels. These radiometers will calculate the

amount of radiation that is reflected by the

Earth’s surface and the amount reflected by

clouds. Comparing these measurements will

allow a better understanding of the role that

clouds play in regulating the earth’s climate.

Measurements of reflected radiation and the

reflective efficiency of different cloud types will

enable development of global oceanic and atmospheric models.

The Moderate Resolution Imaging Spectroradiometer—(MODIS), will be used to measure

biological and physical processes that do not

require along-track pointing. These applications

will include long-term observation of surface

processes/global dynamics such as: surface temperature; ocean color; chlorophyll fluorescence;

concentration of chlorophyll; vegetation cover,

productivity; fires; snow cover/reflectance; cloud

cover; cloud properties. Data collected by MODIS

will be used to take global measurements of

chlorophyll, dissolved organic matter and other

constituents that provide insight about ocean

productivity. MODIS will provide data useful to

the determination of the role of the oceans in the

32 Shelby G. Tilford, Gregory S. Wilson and Peter W. Backhmd, “Mission To Planet Earth,” paper presented at the 42d Cong. of the

International Astronautical Federation Oct. 5-11, 1991, Montreal, Cam&.

33 f ‘DiscoveV t. ~mch Ffit Element of NASA’S Mission t. PIanet Em’ ‘A}ian”on Week a~SPace Tec~no/ogy, Sept. 9, 1991, pp. 63-67.

~ Ibid.

35 For a more complete description of EOS in~~ents, sm NASA’s 1993 EOS Reference Handbook, NASA, Eti Science SUppOll OffiCe.
106 I Remote Sensing From Space

3.

4.

5.

global carbon cycle. These data will have applications in models as well as providing information regarding the productivity of aquatic and

terrestrial plants. Measurements of total precipitation and aerosol properties will also be facilitated by MODIS measurements.

The Multiangle Imaging Spectra-Radiometer

(MISR) will be the only EOS instrument that will

provide information on cloud and surface angular reflectance. The instrument is designed to

obtain images of each scene from multiple angles

and in four spectral bands. The data are collected

using nine charged-coupled device (CCD)

pushbroom cameras. Measurements taken by

MISR will allow researchers to determine the

effects of aerosols in the atmosphere, understand

how different cloud types affect the radiation

budget, evaluate some changes in the Earth’s

forest and deserts, and study aspects of interaction between biophysical and atmospheric processes.

The Advanced Spaceborne Thermal Emission

and Reflection radiometer (ASTER) is an imaging radiometer that will be used to provide high

spatial resolution images of land, water, and

clouds. ASTER is one of Japan’s contributions to

the EOS program. Images taken in the visible and

near infrared, shortwave infrared, and thermal

infrared wavelengths will be used in the study of

soil and rock formations, to monitor volcanoes,

and to measure surface temperatures, emissivity

and reflectivity. The visible and near infrared and

shortwave infrared channels will also have the

ability to provide information on land use

patterns and vegetation. The very near infrared

and thermal infrared capabilities will provide

information on coral reefs and glaciers. Some

evaporation and land and ocean temperature

readings will be possible as well.

Measurements of Pollution In The Troposphere,

or MOPITT, a correlation spectrometer, will

provide measurements of pollution in the troposphere at three wavelengths in the near infrared.

It will specifically measure levels of carbon

monoxide and methane.

NASA plans to include the Earth Observing Scanning Polarimeter (EOSP) on the second AM platform

(an earlier flight of EOSP was rejected by NASA—see

app. B). EOSP will be designed to map the radiance

and linear polarization of reflected and scattered

sunlight through 12 spectral bands, and provide global

measurements of aerosol distribution and cloud properties. EOSP is a polarimeter that scans cross-track,

providing a global profile of aerosol optical thickness.

These data will correct clear-sky ocean and land

measurements that are of critical importance to other

optical measurements of the Earth’s surface.

In addition to EOSP, AM-1 will carry a second

instrument not on the first AM platform. The Tropospheric Emission Spectrometer (TES) will be an

infrared imaging spectrometer that will provide global

three-dimensional profiles of all infrared-active species from surface to lower stratosphere. This information will be used to study greenhouse gases, tropospheric ozone, precursors of acid rain, and gas

exchange in the stratosphere leading to ozone depletion.

EOS COLOR

EOS-Color (1998) will measure oceanic biomass

and productivity.

. The Sea Wide Field of view Sensor (SeaWiFS-11)

will be a multi-band (8) imager that will operate

in the very near infrared portion of the spectrum.

SeaWiFS will be used to observe chlorophyll,

dissolved organic matter and pigment concentrations in the ocean. The sensor will contribute to

understanding the health of the ocean and concentration of life forms in the ocean.

EOS AERO

EOS-Aero (2000) will measure atmospheric aer0s01s.

. The Stratospheric Aerosol and Gas Experiment

(SAGE III) will be a grating spectrometer,

designed to obtain global profiles of aerosols,

ozone, water vapor, nitrous oxides, airborne

chlorine, clouds temperature and mesospheric,

stratospheric and tropospheric pressure. SAGE is

a follow-on to earlier instruments of the same

name. SAGE III will be self-calibrating, and will

have a better vertical range than its predecessors.

EOS-PM

EOS-PM (2000) will examine clouds, precipitation and the Earth’s radiative balance; will meas-
Appendix A—Research and the Earth Observing System I 107

ure terrestrial snow a nd sea ice; observe sea surface

temperature and monitor ocean productivity.

CERES (see above).

MODIS-N (see above).

The Atmospheric Infrared sounder (AIRS) is a

high spectral resolution sounder that will provide

temperature and humidity profiles through

clouds. It will measure outgoing radiation and be

able to determine land skin surface temperature.

In addition, the sounder will be capable of

determining cloud top height and effective cloud

amount, as well as perform some ozone monitoring.

The Advanced Microwave Sounding Unit (AMSUA) and the Microwave Humidity Sounder (MHS)

are both microwave radiometers that will provide

all weather atmospheric temperature measurements from the surface up to 40 km (AMSU) and

atmospheric water vapor profiles (MHS).

The Multifrequency Imaging Microwave Radiometer (MIMR) will provide passive measurements of precipitation, soil moisture, global snow

and ice cover, sea surface temperature, cloud

water, water vapor and wind speed, MIMR will be

provided to NASA by the European Space

Agency.

EOS-ALT

EOS-Alt (2002) will observe ocean circulation

and ice sheet mass balance using the following

instruments:

●

●

The EOS altimeter (ALT) will be a dual frequency

radar altimeter. ALT will provide mapping data

for sea surface and polar ice sheets. The return

pulse of the radar can also provide information on

ocean wave height and wind speed.

The Geoscience Laser ranging system and altimeter (GLRS-A) will be tailored to measure geodynamic, ice sheet, cloud, and geological processes and features.

EOS-Chem

EOS-Chem (2002) will track atmospheric chemical species and their transformations; and measure

ocean surface stress.

●

●

●

The High Resolution Dynamics Limb Sounder

(HIRDLS) will be an infrared seaming radiometer that derives from similar units deployed on the

Nimbus and UARS satellites, It will be used to

sound the upper troposphere, stratosphere and

mesosphere to determine temperature; concentrations of O3

, greenhouse gases, and aerosols;

locations of polar stratospheric clouds/cloud tops.

The Active Cavity Radiometer Irradiance Monitor (ACRIM) is designed to measure solar output

and variations in the amount of radiation that

enters the atmosphere.

The Stratospheric Aerosol and Gas Experiment

(SAGE III) will be the third in a series of similar

instruments. See description under AERO, above.

Microwave Limb Sounder (MLS) is a passive,

limb sounding radiometer, The MLS will be

designed to study and monitor atmospheric processes that affect ozone. Particular emphasis will

be given to the impact of chlorine and nitrogen.

NASA may try to fly the GPS Geoscience

Instrument (GGI) aboard the Chem satellite. GGI

will be designed to contribute to the accuracy of

mapping data collected by other sensors (down to

the centimeter level). It will also play a role in

ionospheric gravity wave detection.

The primary EOS spacecraft, AM and PM, will be

replaced over time to ensure at least 15 years of

coverage, Follow-on payloads will remain flexible to

meet needs as determined by the evolution of scientific

understanding derived from earlier launches.3b

~ Sbtement by L.A, Fisk Associate Adrninisrrator for Space Science and Applications, National Aeronautics and Space Admink-tiou

before the Subcommittee on Science, Technology and Space, Committee on Commerce, Science and Transpotitiou United States Senate

(102d Cong.), Feb. 26; 1992.
Appendix B:

The Future

of Earth

Remote Sensing

Technologies

T

his appendix examines technology issues associated with the

research, development, and acquisition of future U.S. civilian

Earth observation systems. It begins with a review of EOS

science priorities and the effect of EOS program restructuring

on the development of advanced remote sensing technology. This

appendix also discusses ongoing efforts to develop affordable and/or

less risky versions of several large EOS “facility” instruments that

were deferred or deleted during program restructuring. Next, the

appendix briefly summarizes sensor platform and design considerations, including design compromises and tradeoffs that must be made

to match a particular mission with an appropriate sensor and platform

combination.

Finally, this appendix explores the state of the technical ‘ ‘infrastructure’ for future space-based remote sensing efforts. Researchers

interviewed by OTA generally believed that planned efforts in

technology development at the component level were sufficient to

develop next-generation sensors. However, they were less sanguine in

their assessment of efforts fo r ‘‘engineering’ development, fo r

example, the packaging and prototyping of integrated, space-qualified

sensors. Engineering development, while not as glamorous as basic

science, is essential if the United States wishes to reduce the size,

weight, and cost of space-based sensors and platforms. As discussed

below, engineering issues also enter into debates over the maturity of

proposals to develop new small satellites.

Introducing advanced technologies in Earth remote sensing systems

raises several issues, including the role of government in identifying

and promoting R&D for Earth remote sensing; and the timing of the

introduction of new technologies in operational remote sensing

programs. NOAA’s problems with the development of its GOES-Next

environmental satellite system brought the latter issue to congressional

attention (see ch. 3). The issue has also arisen in connection with the

selection of sensors for Landsat 7,now scheduled for launch in 1997.

109
110 | Remote Sensing From Space

Finding a balance between the risks and potential

benefits of technical innovation is a particular problem

in satellite-based remote sensing systems because

these systems are characterized by long lead times and

high costs. Payload costs are a sensitive function of

satellite weight and volume. 1 In principle, satellite

weight and volume might be reduced by incorporating

advanced technologies, now in development, with next

generation spacecraft, However, in practice, proposed

new instrument technologies are often at an early stage

of development and have not demonstrated the ability

to provide the stable, calibrated data sets required for

global change research. In addition, they may not have

the fully developed data processing systems and

well-understood data reduction algorithms required to

transform raw data into useful information. 2 The

requirements for stability, calibration, and welldeveloped data analysis systems are particularly evident in long-term monitoring missions.

Historically, programs have attempted to minimize

risk in satellite programs by introducing new technologies in an evolutionary reamer, typically only after

subjecting them to exhaustive tests and proving

designs in laboratory and aircraft experiments.3 Although experts generally agree on the desirability of

accelerating this relatively slow process, they do not

agree on the risk that would be associated with a

change in the traditional development cycle.4 The

risks in developing a new sensor system have two

components: the technical maturity of component

technologies (e.g., the detector system), and the

design maturity. A particular design that has not

been used before may be a relatively risky venture

for an operational program, even if it is based on

proven technology.5

Efforts to develop and flight-test emerging technologies have been limited by a number of factors,

including budget constraints; scientific disputes over

the merits of specific proposals; intra-agency and

inter-agency rivalries; and the absence of a coherent

strategy for remote sensing, developed within the

executive branch and supported by the relevant authorization and appropriation committees of Congress.

These problems are embedded in an issue of even

greater concern to global change researcherwhether it will be possible to sustain institutional

commitments, including those from NASA, DOE,

and DoD, for periods of time that are long compared to the time for changes in the executive

branch and in Congress. Without such a commitment, much of the current effort to develop strategies

and instrumentation to monitor important climatological variables could be wasted.

| Technology and the Restructured Earth

Observation System

In conjunction with its international partners, the

United States plans a program of Earth observation

systems to provide, by the early years of the next

century, comprehensive monitoring of Earth resources,

weather, and natural and human-induced physical and

1 U.S. Congress, Oftlce of Technology Assessment, Affirtib/e Spucecrafi: Design and Launch Alternatives, OTA-TM-ISC-60

(Washington, DC: U.S. Government Printing Office, September 1990).

z The complex analysis required to measure the Earth’s radiation budget (discussed below) provides an illustrative example.

~ For example, in the 1960s and 1970s NASA and NOAA had a successful 3-stage process for instrument development: (1) technology

de}elopmenr was supported via an Advanced Applications Flight Experiments (AAFE) program for new instrument concepts, usually leading

to tests on aircraft flights, (2) research space j7ighrs were provided for promising instruments graduating from AAFE, on the Nimbus satellite

series, with flights every 2 or 3 years, (3) opera(iona/ satellites carried instruments selected from those tested via the fhst two stages.

i A phased development cycle has traditionally been used to procure operational systems. The steps in this cycle can be grouped as follows:

Phase A—Study Alternate Concepts

Phase B—Perform Detailed Design Definition Study (manufacturing concerns addressed in this stage)

Phase C—Select Best Approach/Build and Tesl Engineering Model

Phase D-Build Fllght Pwtotypc and Evaluate on Orbit

This approach should be contrasted with a ‘‘skunk-works’ approach which omits some of these steps. Historically, the skunk-works

approach has usually been thought more risky than the methodical approach. As a result, it has been used mostly for demonstrations and

experiments.

s Recognizing this problem, the Advanced Research Projects Agency (ARPA) has proposed several advanced technology demonstrations

(ATDs) on small satellites that, if successful, would rapidly insert technology and shorten acquisition time for larger satellites. These

demonstrations would couple innovative sensor design with a scalable high-performance common satellite bus that would employ a novel

“bolt-on” payload-bus interface.
—.

Appendix B—The Future of Earth Remote Sensing Technologies I 111

chemical changes on land, in the atmosphere, and in

the oceans (see chs. 3-5). NASA’s Earth Observing

System of satellites is the centerpiece of NASA’s

Mission to Planet Earth. NASA has designed EOS to

provide 15 years of continuous high-quality data sets

related to research priorities recommended by the

Intergovernmental Panel on Climate Change (IPCC)

and the Committee on Earth and Environmental

Science (CEES) of the Federal Coordinating Council

for Science, Education, and Technology (FCCSET)

(table 5-1 ). To achieve 15-year data sets, each of two

EOS polar platforms, with a design life of 5 years,

would be flown three times. Most scientists believe an

observation period of 15 years is long enough to

observe the effects of climate change resulting from

the sunspot cycle (11 years), several El Nino events,

and eruptions of several major volcanoes. It should

also be possible to observe some effects of deforestation and other large-scale environmental changes.

Scientists are less certain whether 15 years is long

enough to distinguish the effects of anthropogenic

greenhouse gases on Earth’s temperature from natural

background fluctuations. Ecological studies of the

health and migration of terrestrial systems also require

longer continuous records (on the order of 20-50

years).

Intermediate-size, polar-orbiting satellites are the

principal EOS platforms for sensors gathering global

change data.6 Measurements for MTPE can be broadly

divided into two types:

1. Long-term monitoring-to determine if climate

is changing, to distinguish human-induced from

naturally induced climate change, and to determine global radiative forcings and feedbacks

(box B-1).

2, Mechanistic or “process” studies-detailed analysis of the processes that govern phenomena

ranging from the formation of the Antarctic

ozone hole to the gradual migration of tree

species. 7

Global change researchers disagree over whether the

EOS program as currently configured is optimally

designed to perform these different missions and

whether the EOS program will address the most

pressing scientific and policy-relevant questions. EOS

program officials point to repeated and extensive

reviews by interdisciplinary panels in the selection of

instruments and instrument platforms as evidence that

their program is properly structured. Program officials

also note that payload selection panels followed

priorities set by members comprised mostly of theorists who would be the users of data, rather than

instrument builders hoping for approval of a particular

mission. Nevertheless, some Earth scientists express

concern that:

The limitations of satellite-based platforms will

prevent process-oriented studies from being performed at the level of detail that is required to

address the most pressing scientific questions;

Continuous long-term (decadal time-scale) monitoring is at risk, because of the high-cost, long

lead times, and intermittent operations that have

historically characterized design, launch, and

operation of large multi-instrument satellite platforms.

According to this view, a more “balanced” EOS

program might have greater support for small satellites

and a more balanced USGCRP program might include

greater support for groundbased measurement proA These arc multl-instrument satelhtcs and are relatively expensive. For example, NASA estimates that total hardware development costs

for the EOS AM-1 satellite and Its sensors will approach .$800 million. This figure does not include launch costs, which are expected to bq

$100150 m]llmn, or gnwnd segment and operatlrms costs. EOS AM-1 includes the U.S.-developed MODIS, MISR, and CERES instruments

and the forei.grl-suppllcd ASTER and MOPIIT instruments (provided at no cost to build to the United States).

The cojt of bulldlng followr-ons m the AM series would be substantial} less as much of the initial cost is associated with nonrecuning

Instrurnerrt .ind $pacccraft bus (icjign :md development costs and one-time acquisition of ~ground support elements. Savings of 50 to 70 percent

may hc powble, depending on the acqu]slt ion time-schedule. EOS PM series of multi-instrument satellites will not be a copy of the AM series.

( ‘osts for PM-1 are expected to be s]milar, but somewhat lower, than for AM-1. Follow-ons to the PM series may not be as expensive as

follow-on.s m the AM-l sencs because most of the PM instruments are repeated.

~ Sclcntists make no clear (ielineatirm between process studies and monitoring studies. In general, global change researchers use the term

‘ ‘process study ‘‘ to refer to short-term less costly, and more focused experiments that aim to elucidate the details of a particular mechanism

of some geophysical, chcrnlcal, or biological inter,ic( ion. The distinction is least useful for studies of the land surface, which may require years

or more of study (for example, studies of terrestrial ecosystems may require a decade or more of obscmati~n [o s~dY a P~~ticul~ Process such

as migratmn of tree species).
112 I Remote Sensing From Space

Box B-1-Climate Forcings and Feedbacks

Climate forcings are changes imposed on the planetary energy balance that alter the global temperature;

radiative feedbacks are changes induced by climate change. Forcings can arise from natural or anthropogenic

causes. Examples of natural events are the eruption of Mt. Pinatubo in June 1991, which deposited sulfate

aerosols into the upper atmosphere, and changes in solar irradiance, which scientists believe may vary by several

tenths of a watt/m2 per century (the Earth absorbs approximately 240 watts/m2 of solar energy). Examples of

anthropogenic forcings appear in the table “Human Influence On Climate,” below. At present, the dominant climate

forcing appears to be the increasing concentration of greenhouse gases in the atmosphere.

The distinction between forcings and feedbacks is sometimes arbitrary; however, forcings can be understood

as quantities normally specified in global climate model simulations, for example, C02 amount, while feedbacks

are calculated quantities. Examples of radiative forcings are greenhouse gases (C02, CH4, CFCS, N2Q 03,

stratospheric H20), aerosols in the troposphere and stratosphere, solar irradiance, and surface reflectivity.

Radiative feedbacks include clouds, water vapor in the troposphere, sea-ice cover, and snow cover. For example,

an increase in the amount of water vapor increases the atmosphere’s absorption of long-wave infrared radiation,

thereby contributing to a warming of the atmosphere. Warming, in turn, may result in increased evaporation leading

to further increases in water vapor concentrations.

The effects of some forcings and feedbacks on climate are both complex and uncertain. For example, clouds

trap outgoing, cooling, longwave infrared radiation and thus provide a warming influence.1 However, they also

reflect incoming solar radiation and thus provide a cooling influence. Current measurements indicate t hat the net

effect of clouds is a cooling one. However, it is uncertain if the balance will shift in the future as the atmosphere

is altered by the accumulation of greenhouse gases.

An example of a radiative forcing whose effect on climate is uncertain is ozone. The vertical distribution of

ozone (O3) affects both the amount of radiation reaching the Earth’s surface and the amount of re-radiated infrared

radiation that is trapped by the greenhouse effect. These two mechanisms affect the Earth’s temperature in

opposite directions. Predicting the climate forcing due to ozone change is difficult bemuse the relative importance

of these two competing mechanisms is also dependent on the altitude of the ozone change. Calculations by Dr.

James Hansen of the Goddard Institute for Space Studies indicate that ozone loss in the upper stratosphere warms

the Earth’s surface because of increased ultraviolet heating of the troposphere; ozone addition in the troposphere

warms the surface moderately; and ozone loss in the tropopause causes a strong cooling because the low

temperature at the tropopause maximizes the ozone’s greenhouse effect.2

1 V. ~manathan, Bruce R. Barkstrom, and Edwin Harrison, “Climateandthe Earth’s Radiation Budget,” phySiCS

Today, vol. 42, No, 5, May 1989, pp. 22-32.

2 me tmvs~ere, or loWr atmosphere, is the region of the atmosphere where =dr is most den= and where most

weather occurs. By this definition, the troposphere extends from the surface to altitudes of roughly 30,000-50,000 feet.

In dear sky, the tropxphere is Iargefy transparent to incoming solar radiation, which is absorbed at the Earth’s surface.

The temperature of the atmosphere falls steadily with increasing altitude throughout the troposphere (normaliy

several ‘F per 1,000 feet altitude). The heat transfer by turbulent mixing and convection that results from this variation,

the coupling of the Earth’s rotation to the atmosphere, and latitudinal variations in temperature are responsible for the

development and movement of weather systems. Troposphere temperatures reach a minimum at the tropopause, the

boundary between the troposphere and the stratosphere, and then remain approximately constant through the iower

stratosphere. The temperature rises again in the upper stratosphere. The tropopause can reach temperatures as low as

185 K (-126 oF) in the polar winter.
Appendix B—The Future of Earth Remote Sensing Technologies I 113

Human Influence On Climate

Fossil Fuel Combustion

● CO2 and N2O emission (infrared (IR) trapping)

. CH4 emission by natural gas leakage (IR trapping)

. NO, N02 emission alters 03 (ultraviolet absorption and IR trapping)

. Carbonaceous soot emission (efficient solar absorption)

. S02-Sulfate emission (solar reflection)

Land Use Changes

● Deforestation (releases C02, increases albedo, and increases snow albedo feedback)

. Regrowth (absorbs C02

, decreases albedo, and decreases snow albedo feedback)

. Biomass burning (releases C02

, NO, NOZ, and aerosols)

● Landfills (releases CH4)

Agricultural Acfivity

● Releases CH4 (IR trapping)

● Releases N20 (IR trapping)

/ndustrial Activity

● Releases CFCS (IR trapping and leads to ozone destruction)

. Releases SF6

, CF4, and other ultra-longlived gases (IR trapping virtually forever)

SOURCES: J. Hansen, W. Rossow, and 1. Fung, ‘(Long-Term Monitoring of Global Climate Forcings and Feedbacks,” Proceedings of a

Workshop held at NASA Goddard Institute for Space Studies, Feb. 3-4, 1992; and Johan Benson, “Face to Face,” Interview with James

Hansen, Aerospace America, April 1993, pp. 6-11. Table on human influenee on climate adapted from Dr. Jerry D. Mahlman,

‘

(Understanding Climate Change,”’ Draft Theme Paper, prepared for Climate Researeh Needs Wwkshop, Mohonk Mountain House, Nov.

8, 1991. I

grams, including ocean measurement systems, and thought to be most in need of improved scientific

alternative sensor platforms, such as long-duration,

high-altitude unpiloted air vehicles.

The USGCRP and National Space Policy Directive

7 have assigned the lead role in enabling global

observations from space to NASA (see ch. 2). Greater

support for the non-space-based elements of the

USGCRP would provide important data that would

complement or correlate data derived from spacebased platforms. Officials from the USGCRP, NASA,

and NOAA who attended a February 1993 OTA

workshop were unanimous in their belief that relatively modest additions of funds could produce substantial increases in scientific output.8

In restricting the EOS program (see ch. 5) NASA

has sought to emphasize those global change issues

understanding to support national and international

policymaking activities. This has affected both mission priorities and instrument selection. The restructured program’s first priority is acquiring data on

global climate change. As a result, NASA has

deferred missions designed to improve scientific

understanding of the middle and upper atmosphere and

of solid Earth geophysics. Instruments affected by this

decision include new sensors for very high-resolution

infrared, far-infrared, and submillimeter wave spectroscopy.

Deferral of instruments to monitor solid Earth

physics, which includes the study of crustal and ice

sheet movements, was based on the relative unimportance of these processes to global climate change. A

8 For example, several officials agreed that increases in USGCRP budgets on the order of $100 million per year for correlative measurements

would ‘ ‘double scientific output. Greater support for complementary non-space-based elements of the USGCRP could be provided either by

redirection of already tight NASA budgets, from greater support for the USGCRP within the DOE, DoD, and other relevant departments and

agencies, or from increases in USGCRP budgets. EOS program officials are empbatic in stating that their already reduced budget has little

flexibility to accommodate further reprogramming. A discussion of this and related issues will appear in a forthcoming OTA background paper,

‘‘EOS and USGCRP: Are We Asking and Answering The Right Questions?’
114 I Remote Sensing From Space

Figure B-l—Physical Processes Operating In the Stratosphere

Ultraviolet (UV)

radiation

Catalytic

chemistry

Solar UV \

Chemistry

and dynamics

o

N 02

—.. —.— > H 02

Clo

<’- ‘

- -

‘ -

Trace species

transport

\

Temperature

forced winds

Troposphere

The arrows show interactions between imposition and atmospheric renditions. Maintenance of the stratospheric ozone layer,

which shields terrestrial life from solar UV radiation, is of prime concern.

SOURCE: “Protecting the Ozone Layer,” Energy and Technology, May, June 1990, p. 50.
Appendix B—The Future of Earth Remote Sensing Technologies I 115

different reasoning may account for the decision to

defer instruments to monitor stratospheric chemistry

and, in particular, ozone depletion (figure B-l). The

United States and other nations had already agreed to

steps that would phase out the use of ozone-depleting

chlorofluorocarbons (CFCS). Furthermore, even without the EOS instruments, NASA officials could

anticipate improvements in understanding of upper

atmosphere chemistry and the mechanisms for ozone

depletion as data from UARS, a precursor satellite to

EOS, was combined and analyzed with data from

groundbased, and in-situ balloon and aircraft measurements.

However, assessment of the success of efforts to

stabilize ozone reductions may be hampered by the

deferral of instruments to monitor the upper atmosphere. In addition, elimination of missions that might

provide a detailed understanding of the fundamental

processes that are causing ozone depletion in the lower

stratosphere increases the risk that the United States

and other countries will be unprepared to respond to

future “surprises” with respect to ozone depletion.10

Similarly, detailed process studies are necessary to

measure the sources and sinks of carbon dioxide and

other greenhouse gases. Without this knowledge,

regulative and mitigative actions cannot be made with

high confidence that the desired effect (for example,

decreased rate of CO2 increase) will occur as anticipated.l 1

U.S. policy makers are divided on the question of

what, if any, steps the United States should take to

reduce the emission of greenhouse gases. 12 E OS

instruments will supply some of the needed scientific

data on the effect of greenhouse gases on global

warming (box B-2). Ultimately, researchers hope to

advance climate models to the point where reliable

predictions can be made about the magnitude of global

warming and regional effects. Policymakers regard

this information as essential to guide adaptation or

mitigation efforts. In contrast, although the physical

and chemical processes governing the depletion of

ozone in the upper atmosphere have many uncertainties, the international community has agreed to reduce

CFC emission in hopes of reducing ozone depletion.

This difference in approach is clearly related to the

availability of relatively inexpensive alternatives to

CFCS. Pressure to act despite uncertainty was also

influenced by predictions that various CFCS would

reside in the stratosphere for 50 to 150 years after

emission. In addition, aircraft and satellite observations of a growing ozone hole in the Antarctic fueled

public pressure for action to stabilize ozone levels.

Steps to mitigate the effects of ozone depletion or

global warmin g will require financial or other sacrifices. The relative cost of these mitigative efforts may

be highest in developing nations. Building an international consensus on the appropriate steps to

mitigate ozone depletion and possible global warming will require a USGCRP program organized to

answer the most important scientific questions.

“Good policy” is most likely to flow from “good

science. ”

The rest of this section discusses three key instruments that were delayed or not funded:

s Solar ultraviolet radiation is the principal source of energy in the stratosphere and is responsible for many important photochemical

processes. Ozone is concentrated in the stratosphere at altitudes between approximately 65,000 and 100,000 feet. The absorption of solar

ultraviolet radiation by ozone is responsible for the increase in temperature with altitude that characterizes the stratosphere. The stratosphere

is coupled to the lower atmosphere chemically (through photochemical processes), radiatively, and dynamically (various global circulation

processes). See discussion and figure 4 in V. RamanathaL Bruce R. Barkstsou and Edwin HarrisoG “Climate and the Earth’s Radiation

BudgeC’* Physics Today, vol. 42, No. 5, May 1989, pp. 22-32.

10 UARS is not a long-term monitoring satellite-its various instruments have expected lifetimes that range from approtitely 14 monti

to 4 years. Currently, there is no planned follow-on to UARS. Although some of its instruments will fly on EOS platforms, a gap of several

years in time-series of data is likely.

11 Jerry D. Mahhmq “Understanding Climate Change, ” Draft Theme Paper prepared for Cthnate Research Needs Workshop, Mohonk

Mountain House, Nov. 8, 1991.

12 poliw Options for tie Ufitd Sbtes Me a~v~ ~ us Conwss, Offim of T~~o@y Assessmen~ Changing by Degrees: Steps tO

Reduce Greenhouse Gases, OTA-O-482, (WashingtoIL DC: U.S. Government Printing Ofllce, February 1991).
116 I Remote Sensing From Space

Box B-2–The Greenhouse Effect

The Earth’s atmosphere is composed of approximately 78 percent nitrogen, 21 percent oxygen, and a host

of trace gases such as water vapor, carbon dioxide, and methane. Although these gases are nearly transparent

to solar radiation, atmospheric water vapor, water in clouds, and other gases absorb about 20 percent of the

incoming solar radiation, An additional 30 percent of the incoming solar radiation is scattered or reflected,

especially by clouds, back into space. By contrast, the atmosphere is opaque to the less energetic infrared

radiation emitted by the Earth’s surface. About 90 percent of this heat energy given off the surface is absorbed

by the clouds, water vapor, and trace gases such as C02, methane, and chlorofluorocarbons that are being

increased by human activities.

Once absorbed in the atmosphere, the heat energy is reradiated, much of it back to the surface which can

be further warmed, leading in turn to increased heat emission to the atmosphere and further absorption and

reradiation to the surface. In this way, clouds, water vapor, and other trace gases have the effect of warming the

surface (however, as noted above, clouds also cool the surface by reflecting incoming solar radiation back to

space). In fact, the recycled energy reemitted from the atmosphere to the surface is nearly twice the energy

reaching the surface from the Sun. It is this “greenhouse effect” that makes the Earth’s climate different from the

Moon. The analogy is not perfect, however, because it suggests that the atmosphere and the glass in a

greenhouse lead to warming by the same mechanisms of trapping and reradiation. A greenhouse actually stays

warm because the glass keeps the atmospheric moisture from escaping (which is why effective greenhouses are

always humid), thereby reducing the cooling effect of evaporation. Despite the difference in how the mechanisms

work, the term “greenhouse effect” has stuck, providing us with a reminder that allowing continued increases in

the concentration of trace gases (and associated increases in the water vapor concentration) will eventually lead

to future warming.

SOURCE: Quotation from “Systematic Comparison of Global Climate Models,” Lawrenee Uvermore National Laboratory, Energy and

Ttinology Review, May-June 1990, p. 59.

1. LASER ATMOSPHERIC WIND SOUNDER– ters to accuracies of 2 to 3 meters/second. Scientists

LAWS would not only use this information in numerical

LAWS is a proposed Doppler laser radar13 that weather prediction,14 but also to understand a number

would allow direct measurement of tropospheric winds of climate processes, including the transport of water

with high resolution. As conceived by NASA, LAWS vapor in the atmosphere and the heat, mass, and

would provide wind speed and direction at different momentum coupling between the ocean and the

altitudes in the troposphere every 100 square kilome- atmosphere. In addition, if successful, LAWS would

13 ASO c~]ed li&r, for light ra&r. The Doppler shift is the change in laser frequency of the retur% which 1S prOpOttiOrEd tO the s@ter~’s

radial motion relative to the laser source. A familiar analog to this is the change in pitch that is heard as an ambulance siren or train whistle

approaches and then recedes from a stationary observer.

In operatiou a LAWS satellite would transmit a pulse of laser energy towards the - some of which would be scattered back to the satellite

by atmospheric clouds and aerosols. Scatterers in clouds and aerosols move with the local wind velocity. Therefore, wind velocities can be

determined by analyzing the return signal’s Doppler shift. The different altitudes at which the wind velocities are measured is determined by

analyzing the round-trip travel time of the laser pulse.

14 me input for nw~c~ w~ther prediction models are maps of temperature, water vapor, md wind speeds and directions defined over

a global network of model gridpoints. These maps, which may contain some 1,000,000 values, specify an ‘‘initial state’ of the atmosphere.

Numerical weather prediction consists of using model equations to advance this initial set of data to a new set at a later time. Current systems

are limited in their capabilities because they tack access to global wind fields.

It might be thought that wind fields could be derived from temperature fields, which ean be roughly determined with current satellite systems.

Although there are dynamical relations between temperature fields and wind fields, wind measurements have more information than do

temperature measurements, especially for the smaller scales of motion that are of key importance for weather prediction. Source: Cecil bi@

Lawrenee Livermore NationaJ Laboratory, private communication.
Appendix B—The Future of Earth Remote Sensing Technologies I 117

allow the determination of the distribution of aerosols

and cirrus clouds, and the heights of cirrus and

stratiform15 clouds.

As initially proposed, LAWS was a large instrument

with a mass of some 800 kilograms. It would fly on its

own platform and its solar power supply would be

required to supply some 2,200 watts of continuous

power. 16 A space-based laser wind sounder requires

large amounts of power because of the necessity to

transmit high-power laser pulses and because candidate lasers convert only a small fraction of their input

electrical energy into laser light.17 The LAWS proposal called for a pulsed, frequency-stable CO2 laser

transmitter operating at the 9.11 micron line of the C02

laser system; 18 a 1.5 meter transmit/receive telescope;

and a cooled detector. The laser transmitter would

produce pulses with an energy of approximately 15 to

20 Joules per pulse, with a pulse repetition rate that

could be varied between 1 and 10 pulses per second.

NASA established a 5-year lifetime requirement for

LAWS. With laser repetition rates of 5 to 10 pulses per

second, this is equivalent to requiring reliability over

approximately 1 billion laser pulses. The high cost of

LAWS (according to officials at GE Astro-Space

Division, about $600 million in 1991 dollars) and

uncertainty about the ability of a space-based CO2 laser

to maintain its pulse rate over 5 years were among the

chief reasons that NASA chose not to fund LAWS in

the restructured EOS program. Efforts to demonstrate

that a CO2 laser can deliver billion shot lifetimes led to

the demonstration, by GE in the summer of 1992, of

100 million pulses from a sealed, laboratory system.

GE Astro-Space officials believe that by adding a

small, lightweight (less than 5 kg) gas refill system

containing ten laser fills a LAWS space-based laser

could achieve one billion pulses.

Research into laser alternatives for the CO2 laser is

proceeding in many locations, especially DOE national laboratories. In principle, solid-state lasers

should be less prone to failure than high-power gas

C O2 lasers. 19 However, another potential advantage-the reduction in requirements for laser energy

or the size of telescope optics—is less certain. 20

Development of space-based solid-state lasers for a

LAWS mission will require the resolution of a number

of technical issues.21 Some of these are associated with

15 s~a~om ~]~ud~, ~ ~~cu]m m~ne Stratocmu]us, S]gfificanfly ~fect tie s~fiace heat budget ~d may be important in regulating

climate, Because marine stratocumulus are associated with regions of large-scale subsidence, they are typically not overlain by higher clouds,

and hence would be observable by a space-based laser wind sounder. Source: Dr. Michael Hardesty, NOAA Wave Propagation Laboratory,

Boulder, CO, private communication.

16 ~ an effo~ t. reduce costs, a “descowd’ ‘ LAws ~ ~s.o been s~dl~. ~ls ~s~ent wo~d reduce tie Ouput pOWeT by a factor C)f

3-4 and reduce the telescope diameter to 0,75 meters. A LAWS science team meeting in Huntsville, AL, from Jan. 28-30, 1992, considered

the science implications of building this instrument. They concluded that the descoped instrument could still measure tropospheric winds well

enough to make important contributions to atmospheric general circulation models.

17 For example, the ‘‘wallplug’ eftlciency of the baseline COZ laser is approximately 5 percent,

[g More precisely, this is a line intie ‘W180Z isotope laser, This line is chosen because the reduced abundance of this isotope int.he atmosphere

minimizes atmospheric attenuation.

19 For ewp]e, sohd-smte liners would avoid tie diffl~lties of designfig a long-lived gas ~dling system. They would also avoid the

possibility of failure from electrode “poisoning’ ‘—impurities introduced into the laser as a resutt of sputtering from the electric discharge

elec~odes, (However, based on the demonstration described above, GE researchers concluded that sputtering would not be a serious problem. )

m me ~ser enerm and sim of telescope optics for a laser radar are related to the efficiency of the detection pmcess, w~ch IIMY be m=smed

by the signal-to-noise ratio (SIYi) coming out of the detector, The leading candidate solid-state laser operates at a wz Telength near 2 microns.

A longstanding, and still unresolved, debate within the community of researchers developing LAWS is whether this shorter laser wavelength

system would have overall superior performance compared to the proposed 9.1 micron COZ laser system.

‘1 These include the design of a system to provide the very accurate pointing of the narrow laser beam that is needed to ensure reeeption of

the return signal. In addition, both the optics and the beam quality of UWS would have to be near-perfect (i.e., near diffraction limited

performance) because LAWS would use coherent detection to measure wind velocities. (Coherent detection mixes a stable frequency source

with the return signal to generate a beat frequency that is proportional to the wind velocity,) COZ wind lidars with similar requirements for beam

quality and optics quality have operated successfully on the ground for over a decade,

Several DOE national laboratories are also exploring the potential of noncoherent laser Doppler velocimetry, which would measure wind

velocities without using coherent detection. Noncoherent methods have much lower requirements for pointing accuracy and beam quality.

However, they may be less sensitive than coherent systems and they also have additionat requirements, for example, the necessity to measure

the amplitude of the transmitted and received beam precisely.
118 Remote Sensing From Space

the development of the requisite laser crystals, semiconductor array pumps, and coherent detectors; others

are related to the pointing and stability of the

shorter-wavelength system. Eye safety is also an issue

of greater concern at the operating wavelengths of the

solid state laser than it is with the CO2 laser.

Currently, only the CO2 system is far enough into

development for consideration in early EOS flights.

An effort to find international partners for this system

is underway; GE officials also are exploring potential

collaborations among NASA, DOE, NOAA, and DoD.

2. SYNTHETIC APERTURE RADAR-SAR

NASA originally proposed a SAR for the EOS

program because of its unique ability to make high

resolution global measurements of the Earth’s surface

(see box B-3), but decided not to fund it because of its

probable high cost (over $1 billion in 1991 dollars).

Operating at microwave frequencies, SAR radar returns are sensitive to the electrical and geometric

properties of the Earth’s surface, its cover, and its near

subsurface. These data complement optical imagery

and the combined data set may allow the study of such

important Earth system processes as the global carbon

cycle. Because SARS operate at microwave frequencies they are largely unaffected by clouds. This is

particularly useful for monitoring the intensely clouded

tropical and polar regions of the Earth. Operation

during both day and night is also possible because

SARS, like all radars, provide their own illumination in

the form of radar energy.

SAR data could substantially improve the value of

other EOS data. For example, researchers are particularly excited by the possibility of combining data from

SAR about the physical properties of Earth’s surface

with data about chemical composition from HIRIS (see

below). The combination would have the potential to

date the ages of geomorphic surfaces and thus provide

anew data set that would determine the rates of surface

erosion and deposition.22 A space-based SAR would

also provide digital topographic data, vital for most

hydrologic, geologic, and geophysical investigations.

By using two antennas, SARS can be used in an

interferometric mode to acquire global topographic

data at resolutions on the order of 30 to 50 meters

horizontal, 2 to 5 meters vertical.23

Synthetic aperture radar is a well understood technology with a long heritage of both civilian and

military applications. The U.S. experience in flying

space-based SARS for civilian applications began with

the Seasat mission in 1978 and continued with SAR

missions on Space Shuttle flights in 1981 and 1984

(Shuttle Imaging Radar-A & B). Currently, the Jet

Propulsion Laboratory is preparing a third Shuttle

imaging radar, SIR-C, for l-week flights in 1994-1996

(box B-4). SIR-C will include a German and Italian

X-band SAR (and is therefore sometimes referred to as

SIR-C/X-SAR); the combination of systems will form

a multiangle, multifrequency, multipolarization radar

(a “color” SAR) that will demonstrate the technologies necessary for EOS SAR.24 Foreign experience in

space-borne SARS includes the two SARS currently in

orbit. These systems, built and operated by Japan and

Europe, are free-flying systems designed for multiyear

~ B.L. Isacks and Peter Moughinis-Marlq “Solid Earth p~el, “ in The Earth Observer, vol. 4, No. 1, 1992, pp. 12-19. The Earth Observer

is published by the EOS Project Science Office, Code 900, NASA Goddard Space Flight Center, Greenbelt, MD. As discussed below, budget

cuts forced cancellation of I-IRIS fiorn the EOS program.

2-3 D~ne L Evms, Jet ~p~sion ~borato~, p~soti cOmCnticatiOn, Apr. 20, 1992. The essence of tie ~tefierometic SM ‘Wtique

is to transmit a radar pulse and usc the phase difference in signals received by two antennas, sepamted by a known distance, to infer ground

elevations. The required distance between the separated antennas increases M the frequency is lowered. Thus, for example, bband transmission

would require locating receive antennas on two separate spacecraft. However, at Ka band, both antennas could be located on a single spacecraft

(one located on a boom).

~ me capability to vw radw incidence angle is necessary for measurements that require penetration to the Surface, for example, ~ mapp@

forest clear cuts. SIR-C, which is being developed by the Jet Propulsion Laboratory for NASA, is a two-frequency, multi-polarization SAR

that can vary its angle of incidence from 15c’ to 55°. SIR-C/X-SAR is a joint project of NASA, the German Space Agency and the ItaLian Space

Agency and will be the first spaceborne radar system simultaneously to acquire images at multiple wavelengths and polarizations. X-SAR,

which Germany and Italy are providing, is a single polarization radar operating at X-band (3 cm wavelength). It is mounted on a bridge structure

that is tilted mechanically to align the X-band beam with SIR-C’s L-and C-band beams. SIR-C/X-SAR is scheduled to fly aboard the Space

Shuttle on 3 missions in 1994-1996 and will acquire seasoml data on vegetation, snow, and soil moisture.
Appendix B—The Future of Earth Remote Sensing Technologies I 119

Box B-3-Synthetic Aperture Radar

Spaceborne radar systems may be classified in three general categories: imagers, altimeters, and

scatterometers/spectrometers. Imaging radars are used to acquire high-resolution (few meters to tens of meters)

large-scale images of the surface. They are used for the study of surface features such as geologic structures,

ocean surface waves, polar ice cover, and land use patterns. A synthetic aperture radar is a special type of

microwave radar-a “side-looking radar” (see figure B-2)-that achieves high resolution along the direction of

motion of its airborne or spaceborne platform.

Radar resolution is usually defined as the minimum ground separation between two objects of equal

refIectivity t hat will enable t hem to appear individually in a processed radar image. A sideways-looking radar has

two resolutions: range resolution (“cross-track” resolution), which is perpendicular to the ground track, and azimuth

resolution (“along-track”) resolution, which is in the direction of motion. Range resolution is determined by the

length of the radar pulse because objects at different ranges can only be distinguished if their radar returns do not

overlap in time. Azimuthal resolution is determined in conventional radar systems by the width of t he ground strip

that is illuminated by the radar, which is determined by the antenna beamwidth. Unlike conventional radar, the

azimuthal resolution obtainable with a SAR is not determined by the size of antenna used in the

measurement. A small antenna with a wide field-of-view can make high spatial resolution images by taking many

closely spaced measurements.

Mathematically, an array of antennas is equivalent to a single moving antenna along the array line as long

as the received signals are coherently recorded (i.e., phase information is retained) and then added. The SAR

technique can be applied to spaceborne radar applications where the motion of t he spacecraft allows a particular

object on Earth to be viewed from numerous locations along the orbital path. It can be shown that the best

azimuthal resolution on t he ground using a synthesized array is equal to L/2, where L is the antenna length. This

result is counter-intuitive because smaller antennas have higher resolution and because the ground resolution is

independent of sensor altitude.

In his text on radar remote sensing, Charles Elachi notes that the fact that the resolution is independent of

the distance between sensor and the area being imaged can be understood by noting that the farther the sensor

is from the ground, the larger the footprint, and therefore the longer the synthetic array, This leads to a finer

synthetic beam which exactly counterbalances the increase in distance.

The other surprise of synthetic aperture technique-finer resolution can be achieved with a smaller

antenna-ca n be explained by noting t hat the smaller the antenna, t he larger the footprint and the synthetic array.

This leads to a finer synthetic beam, and therefore, finer resolution, However, smaller antennas gather less energy

than larger antennas. Therefore, for maximum signal-to-noise in the detected signal, a designer may choose the

largest antenna that is consistent with the minimum required resolution and the volume constraints of the

instrument package. (Another way to increase the signal-to-noise would be to increase the time the SAR dwells

in scanning a particular scene; however, platform speed in low-Earth orbit (approximately 7 km/s) places practical

limits on this method.)

The return radar echoes received by a SAR are spread over a time that is proportional to the distance between

the SAR platform and various features in the target. In addition, interference between signals reflected from various

parts oft he target will modify t he amplitudes and the phases of the echo signal pulses. Thus, synthetic aperture

radar signals are unintelligible in their raw form; they must be processed electronically to produce a useful visual

display. Uncompensated motion during aperture synthesis causes a blurring of the resultant SAR image.

Techniques to deblurr these images using novel image processing software/parallel computer processing are

being developed with the support of DOE and DoD.

(continued on next page)

L
120 I Remote Sensing From Space

Spaceborne synthetic aperture radars can achieve ground azimuthal resolutions that are hundreds or even

thousands of times better than those from a real aperture system. (In practice, the azimuthal resolution is often

made equal to the range resolution.) However, they require very fast on-board electronic processing and

high-speed data links to the ground. Data are generated at enormous rates in SARs-for EOS SAR, 180 Mbps

peak, 15 Mbps, average.

Satellite-based SARS have their antenna, power, and data transmission requirements fixed by mission

requirements such as spatial and temporal resolution and radar frequency. For example, the frequency and

altitude of a SAR drive antenna size requirements; the required signal-to-noise ratio is a important factor in

determining transmitter power requirements; and the size and resolution of the area to be imaged dictate the

required data rate. Power requirements scale as the cube of altitude; power-aperture products scale with the

square of altitude.’ Power, size, and weight requirements may be relaxed for aircraft-mounted SAR. However,

compensating for a platform that vibrates and may be buffeted by winds and changing atmospheric conditions

poses new challenges. In addition, aircraft-mounted SAR have the endurance limitations common to all

aircraft-mounted instruments.

1 ~ese fact~s are related byttte “radarequation,” which can be expressed in terms of the observed signai to nh

ratio (SNR). The SNR is dependent on receiver performance. In addition it is proportional to the average transmitted power;

the square of the antenna gain (proportional to area); the cube of the radar wavelength; the target radar “cross section,”

(a measure of target reflectivity); the cross-track resolution (which is related to the bandwidth of the radar processor and

is therefore related to the noise); the inverse cube of the slant range to target; and the inverse of the spacecraft velocit y.

SOURCES: Briefings to OTA, Jet Propulsion Laboratory, January 1992; Chartes Elachi, Spacdwrne Radar Remote Sensing: App/ieat/ons

and Techniques, (New York, NY: The Institute of Electrical and Electronics Engineers, 19SS); and “Radar Images,” in Sandia National

Laboratory, Sandia Technology: Engineering and Scierree Accomplishments, 1992, pp. 32-33.

operation. A similar free-flying Canadian SAR is combined with advances in modeling of radar backscatscheduled for launch in 1995.25

All current and planned foreign space-based SARS

operate in single-frequency, single-polarization mode.

In contrast, the proposed EOS SAR, like SIR-C/XSAR, would be capable of making multiangle, multifrequency, multipolarization measurements. These

capabilities allow more information to be extracted

from an analysis of radar backscatter and would give

EOS SAR the potential to make global measurements

of biomass, soil moisture, polar ice, and geology.26

(Data from aircraft27 and Shuttle-based experiments

ter signals will be necessary to demonstrate that

biomass and soil moisture measurements over vegetated land can, in fact, be made precisely enough to be

useful to global change researchers.) Multifrequency,

multipolarization SARS have been developed for

aircraft experiments, but until recently they have been

considered too challenging and expensive to incorporate in a free-flying spaceborne system.

In principle, EOS SAR could have been used to

monitor and characterize forest growth. Atmospheric

C02 from forests is a key unknown parameter in the

~ See ch. 4: Stiace Remote Sensing and app. D for descriptions of eNsting SAR SateuteS.

26 FOrelw s~5 ~ve more lfit~ ~apabiliti~ for glob~ c~ge res~ch comp~ed to the proposed EOS SAR. The European ERS- 1

operates in C-band (at 5.4 GHz). This frequency is especially suited for mapping sea ice and snow cover, but is not the preferred frequency

for most EOS-class science missions. For example, studies of plant and soil moisture require lower frequency SARS because the lower

frequency penetrates deeper into vegetation and soils. ERS-1 also does not have global coverage. The Japanese JERS-1 operates in L-band (at

1.3 GHz), and is preferred for more science missions. However, JERS- 1 has relatively poor signal-to-noise ratio. Its principal scientitlc objective

is to study geology. The Canadian Radarsat witt be a single frequency and pol arization instrument operating in C-band (at 5.3 GHz), and will

have a wide swath width, but its principal application will be to monitor polar ice in the northern latitudes. (The Russian Alrnaz, which

de-orbited on Oct. 17, 1992, was a single polarization instrument that operated at a frequency near 3.1 GHz in the S-band.)

27 Airborne SARS include tie Jet PmpuIsion Laboratory AIRSAR, a three-frequency pokirnetric SAR that 1S providing prototype data for

the Shuttle Lmaging Radar-C (SIR-C) and the EOS SAR.
Appendix B—The Future of Earth Remote Sensing Technologies I 121

global carbon cycle.

28 EOS SAR would have complemented EOS MODIS, which will monitor C02 uptake

in the oceans, by monitoring the extent of deforestation, the biomass of existing forests, and the successional stage of existing forests. Remote sensing studies

of biomass in the tropical forest require a capability to

sense both the forest canopy structure and the tree

trunks underneath the canopy. Radar returns from the

“C” band of EOS SAR would be sensitive to the

canopy structure while the longer wavelength ‘‘L’

band would be able to penetrate the canopy and give

information about tree height, biomass, and canopy

architecture.29

The principal impediment in developing EOS SAR

is its high cost, a direct result of the requirements for

a high-power system with a large antenna. The

European Space Agency’s ERS-1 SAR cost nearly $1

billion30 and the Japanese JERS-1 cost approximately

$380 million. Early estimates of the cost of EOS SAR,

including ground segment and launch costs, approached $1 billion.

Cost reductions are possible if ways can be found to

lower power and size requirements. Program managers

for EOS SAR generally believe that reducing power,

mass, and size requirements will result from investment in what are, in effect, engineering programs31—

scientists see no near-term technology ‘breakthrough’

that would change this conclusion. As noted earlier,

program officials for both EOS SAR and LAWS raise

concerns that government technology development

efforts generally minimize funding for engineering and

risk reduction programs and instead fund what is

considered more basic science. Yet, investing in

technology development may have significant payoff

in more capable, lower cost technology.

Another option for EOS SAR would be to combine

the data streams from a constellation of co-orbiting

spacecraft, each carrying a single frequency SAR. The

cost of each instrument might be reduced by using a

standard instrument bus. A more substantial opportunity for savings would come from international

collaboration. NASA and its sister agencies in Canada

and Europe have begun informal discussions to

explore the possibility of achieving the multifrequency

capabilities proposed for EOS SAR through international partnerships. The European Space Agency

(ESA) and Canada might provide C-band data (possibly with polarization diversity), the United States

might provide L-band polarimetric data, and Germany

might provide X-band data. To achieve the objectives

of multitemporal observations and data continuity in

the near term, the agencies have discussed develop-

~ The global carbon cycle describes the movement of carbon from i(s sources and sinks in the ocean, atmosphere, and land (e.g., ice pack

tundr% jungles, marshes). For example, during the day, plants take carbon dioxide from the atmosphere and convert it into organic compounds

such as carbohydrates by using solar energy and water (the process of ‘‘photosynthesis’ ‘). Plants emit COZ during respiration, when they use

the energy stored in these compounds. The balance favors the net accumulation of carbon in trees, shrubs, herbs, and roots. When forests are

cut, the effect on atmospheric C02 depends on how much carbon was stored (i.e., total biomass), what happens to the cut wood, and how the

lands are mamged (e.g., new vegetation WI1l take up COZ unless the site IS converted to a reservoir, highway, or other nonvegetative state.

Source: U.S. Congress, Office of Technology Assessment, Changing by Degrees: Steps To Reduce Greenhouse Gases, OTA-0482

(Washington DC: U.S. Government Printing Office, February 1991), pp. 201-203.

29 ~c SAR on tie European EFN- 1 has been limited in its capability to make soil moisture measurements, even though Its frequency and

incidence angle were specifically chosen for this application, because of the problem of differentiating between vegetation cover and ground

moisture. EOS SAR would allow better separation of radar backscatter contributions from the Earth’s surface and its ground cover. In principle,

a multiangle, multifrequency, multipolarization SAR would allow soil moisture to be distinguished from canopy moisture or soil moisture to

be distinguished from vegetation moisture. (Successful tests have occurred in aircraft experiments; however, EOS SAR would have to able

to make similar measurements at an accuracy useful for global change.) The multiple frequency and polarization data of EOS SAR would be

gathered simultaneously. This would allow researchers to monitor processes independent of diurnal or weather effects, for example, monitoring

soil and canopy moisture, which will change from day to night or after a rainfall. Simultaneous measurements are also useful in monitotig

ice in marginal ice zones.

30 ~sfiWe ~cludes tie cost to develop, build, and launch the satellite and to construct a network of ground receiving stations and facilities.

In addition+ the cost includes development of supporting instruments such as the Along-Track Scanning Radiometer. The cost to build a second

radar satellite that would be similar to ERS- 1 and use the existing ground segment is approximately $500 million.

31 Al~ough tie comPnent tw~ologies for an EOS SAR are not new, tie system possesses a number of U@Ue rM@XIlentS tit S@eSS

design and add to cost. For example, special monolithic microwave integrated circuits (MMIC) with exceptionally linear response would be

required. Similarly, specialized efforts would be needed to package SAR components in lighter weight and smaller structures. An attendee at

OTA’S workshop on technologies for remote sensing noted that power efficient MMICS and lightweight antenna structures are examples of

SAR-related technology that have suffered from lack of funding.
122 I Remote Sensing From Space

bm .

Signals collected from different orbital positions are merged to create a narrow synthetic aperture beam.

SOURCE: Japanese Earth Resources Satellite-1 brochure, Japan Rcscurces Observation System Organization.
Appendix B–The Future of Earth Remote Sensing Technologies I 123

ment of a SIR-C/X-SAR flee-flyer in order to provide

multiparameter SAR data prior to an EOS SAR

mission. Discussions regarding exchange of science

team members have been initiated in order to analyze

these options further.

3. HIGH-RESOLUTION IMAGING

SPECTROMETER–HIRIS

Since 1972, the Landsat series of satellites have

imaged most of the Earth land surface at 80-meter

and 30-meter resolution in several relatively broad

visible and infrared spectral bands.32 The reflectance

characteristics of vegetation, soil, and various surface

materials are sufficiently different that they can be

distinguished by the relative strength of their reflectance in various combinations of these bands.

HIRIS was conceived as an ‘‘imaging spectrometer’ capable of making much more refined measurements of the Earths surface than Landsat by acquiring

simultaneous images of the Earth in hundreds of

contiguous narrow spectral bands. In principle, analysis of HIRIS data would allow direct identification of

surface composition; for example, identifying specific

minerals, specific types of trees or ground cover,

pollutants in water, and vegetation under “stress.”33

HIRIS would build on experience with the Airborne

Visible and Infrared Imaging Spectrometer (AVIRIS),

which became operational in 1988.34 NASA’s original

HIRIS proposal envisioned an instrument that would

collect images in 192 narrow spectral bands (approximately 0.01 microns wide) simultaneously in the 0.4 to

2.5 micron wavelength region. This range, from the

visible to the near-infrared, contains nearly all of the

spectral information that can be derived from passive

sensors collecting reflected solar energy.

NASA chose HIRIS’ spatial resolution to be 30

meters in part because of its use in vegetation research

and geological mapping. For example, in forest

Box B-4-Shuttle Imaging Radar

NASA has flown two models of a synthetic aperture

radar on the Shuttle, the Shuttle imaging radar, SIR-A

and SIR-B. Both instruments collected thousands of

images of Earth’s surface between +280 North and

-280 South. SIR-C, an international effort that incorporates more advanced technology, is designed to fly on

the Space Shuttle for l-week experiments in 1994,

1995, and 1996. The United States is providing a

dual-frequency quad-polarization radar operating at

L-band and C-band frequencies; Germany and Italy

will supply an X-band imaging radar. The combined

3-frequency system (sometimes referred to as SIR-C/

X-SAR) is the latest in a series of Shuttle imaging

radars designed to demonstrate the technologies

necessary for an EOS SAR. SIR-C/X-SAR will be

functionally equivalent to EOS SAR and will be used

to identify the optimum wavelengths, polarizations,

and illumination geometry for use by EOS SAR.

However, EOS SAR would not be attached to a shuttle

and would require an independent power source from

solar panels. It would also have more stringent volume

and weight constraints. On the other hand, if launched

on an expendable launcher, a free-flying SAR would

not have to have the safety requirements of systems

that are rated for flight with humans.

SOURCE: Jet Propulsion Laboratory: Briefing to OTA, 1992.

ecosystems, successional changes in vegetation structure and function are linked to the size of gaps created

by tree death, windfall, and other disturbances.35

Thirty meters corresponds to the approximate size

patch that develops in an Eastern hardwood forest

when a tree is felled. It is also the approximate

sz ~ngm time.~erle~ of data is available from the series of Advanced Vev Hi@ Resolution ‘diometer (A

VHRR) sensors that have been

orbited on TIROS polar satellites. AVHRR provides multispectral imaging (2 visible channels; 3 infrared channels), but at much lower

resolution ( 1 km and 4 km).

33 Alexander F. H. Goetz and Mark He*g, “The High Resolution Imaging Spectrometer (HIRIS) for EOS, ” IEEE Transactions on

Geoscience and Remote Sensing, vol. 27, No. 2, March 1989, pp. 136-144. Plant leaf spectml reflectance has been shown to differ when plants

are stressed by a variety of agents including dehydration and fungus attack. See Gregory A. Carter, ‘‘Responses of Leaf Spectral Response to

Plant Stress,” American .lournal of Botany, 80(3): 239-243, 1993.

34 A much ~orc ~emltive “=slon of A~S, ~1~—hypmsp&~ digital i~ging coll~tion experiment-is being developed by the

Naval Research Laboratory for aircraft flight in 1994. HYDICE wI] serve as a testbed for both the technologies that would enable HIRIS and

for advanced aircraft-mounted sensors that could have militay applications in land and ocean surveillance.

35 Goe~ md Herring, op. cit., footnote 33, p 138.
124 | Remote Sensing From Space

resolution needed in some geological applications and

is roughly the minimum resolution necessary to detect

roads. Even higher resolutions may be desirable, but

the combination of hyperspectral imaging, relatively

high spatial resolution, and requirements for large

dynamic range36 already stresses many aspects of

instrument design, especially data handling and transmission.

HIRIS was originally scheduled for flight on the

second EOS-AM platform in 2003. Faced with the

1992 reductions in the proposed outlays for EOS,

NASA deleted HIRIS because of its high probable cost

(more than $500 million in 1991 dollars). Efforts to

design a smaller, lighter, and therefore lower cost

instrument are continuing. Proposals for a smaller

HIRIS include reductions in required ground resolution (which reduces the size of instrument optics and

peak data rates) and the use of active refrigeration to

cool infrared focal plane arrays.37 Establishing the cost

of a smaller, lighter HIRIS is complicated by disputes

over how much to budget to cover unanticipated costs

associated with the introduction of advanced sensor

technologies. Additional research is also required to

establish the utility of HIRIS to support the highest

priority missions of the restructured EOS program.3g

| Platforms: Issues and Tradeoffs

Each remote sensing mission has unique requirements for spatial, spectral, radiometric, and temporal

resolution (box 4-B). Numerous practical considerations are also present, including system development

costs; the technical maturity of a particular design; and

power, weight, volume, and data rate requirements. As

a result, the selection of a “system architecture’ for a

remote sensing mission typically requires compromises and tradeoffs among both platforms and sensors.

For example, some of the factors in determining

system architecture for imaging of the land surface are

the required geographical coverage, ground resolution,

and sampling time-intervals. In turn, these affect

platform altitude, the number of platforms, and a host

of sensor design parameters.

SATELLITE V. NON-SATELLITE DATA

COLLECTION

Remote sensing instrumentation can be placed in

space on platforms that have a variety of orbital

altitudes and inclinations. It can also be flown on

endo-atmospheric platforms: aircraft (e.g., NASA’s

ER-2), balloons, and remotely piloted aircraft.39 Finally, instruments can be sited at well-chosen locations

on the Earth’s surface.

Satellites play a central role in global change

research because they facilitate global, synoptic, and

repeatable measurements of many Earth systems (box

B-l). Thus, for example, satellite-based measurements

are ideal for monitoring changes in global biomass,

land use patterns, the oceans and remote continental

regions, and global processes that have large amounts

of small-scale variability, such as weather.40 However,

satellite-based measurements also have a number of

limitations that only complementary remote sensing

programs can address.

Orbiting above the atmosphere, a satellite-based

remote sensing system gathers information about the

Earth by measuring emitted or reflected electromagnetic radiation. These signals are then manipulated into

forms that can be used as input data for analysis and

interpretation. However, the process that converts

36 sm~or~ ~pable of dete~fig ~i~s hat vary widely in intemi~ (large dynamic range) and characterizing SlgrldS freely (Squantization) are required to analyze scenes of widely varying reflectance and to characterize processes that may have only small differences

in reflection.

37 NASA ~s~fi~ s~l~ cycle mW~c~ c~lers for EOS for approv~ or potential ins~en~ such as AIRS, SWIRLS, TES,

HIRDLS, and SAFIRE. Only the Oxford Stirling cooler is space qualified (a Lockheed mechanical cooler maybe space qualMed in the near

fu hue----it is scheduled for flight in November 1994). Incorporation of mechanical coolers for EOS instruments wilt be possible only if current

expectations for satisfactory cooling power, endurance, and vibration isolation are met.

3S H~S Wm fiti~ly prows~ when geolo@c~ qpfications had a higher priori~. ~S hv~tigatom have been asked to show that

spacebased imaging spectrometry can, in fac~ monitor portions of the carbon cycle. Source: Berrien Moore III and Jeff Dozier, ‘‘Adapting

the Earth Observing System to the Projected $8 Billion Budget: Rmommendations from the EOS Investigators, ” Oct. 14, 1992, unpublished

document available from authors or from NASA Office of Space Science and Applications.

39 some shofl-d~ation ~-sl~ sampling of tie atmosphme CaII alSO be accomplished USing rockets.

40 sate~te.bas~ mWWmen~ are not ne~ssary to measure variables whose dis~bution is approximately UIlifOITll, for example, dle

atmospheric concentration of C02, which can ~ monitored at a few sites on tie gro~d.
Appendix B—The Future of Earth Remote Sensing Technologies I 125

measurements into geophysical variables is often

complex and data from nonsatellite measurements are

necessary to reduce ambiguities in the analysis. Scientists also need to compare satellite data with surfacebased or airborne measurements to verify that the

satellite data are free of unforeseen instrument artifacts

or unforeseen changes in instrument calibration. These

comparisons are particularly important for long-term

measurements and for measurements that seek to

measure subtle changes. Satellite data must also be

corrected to account for the attenuation and scattering

of electromagnetic radiation as it passes through the

Earth’s atmosphere. In addition, corrections are necessary to account for the variations in signal that occur

as a result of changes in satellite viewing angle.41

Another !imitation of sensors on satellites is their

capability to make measurements in the lower atmosphere. They may also be unable to make the detailed

measurements required for certain process studies. For

example, an understanding of the kinetics and photochemistry that govern the formation of the Antarctic

ozone hole (and the role of the Antarctic vortex) has

only been possible with in-situ balloon and highaltitude aircraft experiments.42 Ground and in-situ

measurements also help ensure that unexpected phenomena are not inadvertently lost as a result of

instrument or analysis errors .43 Satellite-borne sensors

are also unable to measure climatological variables to

the precision necessary for certain numerical weather

and climate models, and their ability to determine

temperature, moisture, and winds is inadequate for

meteorologists interested in predicting, rather than just

detecting, the formation of severe storms/hurricanes.

UNPILOTED AIR VEHICLES

Researchers interested in elucidating mechanisms

for ozone depletion are particularly interested in

obtaining a stable, controllable, long-endurance platform that could be instrumented to monitor conditions

in the upper atmosphere at altitudes up to and above 25

km (approximately 82,000 feet). Scientific explorations of this region are currently hampered by the

uncontrollability of balloons, the inadequate altitude

capabilities and high operating costs of piloted aircraft,

and the inadequate spatial and temporal resolution of

satellite-borne instruments.

Several recent studies have concluded that unpiloted

air vehicles (UAVS) are capable of carrying instruments that would provide unique and complementary

data to the NASA’s EOS program and to the DOE’s

groundbased Atmospheric Radiation Measurement

program.

44 For example, high-altitude UAVS would

allow detailed studies of the mechanisms involved in

the formation, maintenance, and breakup of the

Antarctic ozone hole. In turn, this information could

provide researchers with the tools to predictf the onset

of a similar hole in the Arctic. Positioning a UAV

above a heavily instrumented site on the ground would

also allow researchers to obtain accurate vertical

profiles of radiation, water droplets, water vapor, ice

particles, aerosols, and cloud structure-information

that complements surface measurements and that is

essential to test larger-scale models of atmospheric

phenomena (UAVS would characterize processes occurring on a scale of General Circulation Model grid

box, which is several tens of thousands of square

kilometers) .45

41 see Jeff Dozier and Alan H. Strahler, “Ground Investigations in Support of Remote Sensing, ” Manual of Remote Sensing: Theory,

Instruments, and Techniques (Falls Churcb VA: American Society of Phtograrnm etry and Remote Sensing, 1983).

42 J.G. Anderson, D.W. Toohey, W.H. Brune, “Free Radicals Within the Antarctic Vortex: The Role of CFCS in Antarctic Ozone Loss,’

Science, vol. 251, Jan. 4, 1991, pp. 39-46.

43 me diXovW of the $ *ozone hole’ ‘ above ~tarcticapmvides ~ ins~ctive example of tie impo~ce of Wound-bmti observations (bOX

A-3).

~ See Peter Banks et al., “Small Satellites and RPAs in Global-Change Researc~” JASON Study JSR-91-330 (McLea~ VA: JASON

Program Office, The MITRE Corp., July 13, 1992); U.S. Department of Energy, OffIce of Health and Environmental Researe& Atmospheric

Radiation Me~surement Unmanned Aerospace Vehicle and Satellite Program Plan, March 1992 Draft (Washingto~ DC: Department of

Energy, March 1992); and James G. Anderson and John S. Langford, eds., Unmanned Aircraft: An Essential Component in Global Change

Research, version 1.0, June 1991, (available from authors). A popular article that discusses the potential role of UAVs in atmospheric research

appears in Steven Ashtey, ‘‘Ozone Drone, “ Popular Science, vol. 241, No, 1, July 1992, pp. 60-64.

45 Water Vawr and clouds tie tie dominant regulators of radiative heating on the planeL and Uncertainty about tie effmt of clouds o

n cltite

is a source of fundamental uncertainty in climate prediction. Scientists have proposed UAVS for making some of these measurements.
126 I Remote Sensing From Space

Table B-l-Specifications of Airborne Measurement Platforms and Proposed

Conventional Research Aircraft

a Aircraft exists, but not currently equipped for atmospheric research.

SOURCE: Department of Energy, Office of Energy Research, Office of

UAVS are particularly suited towards making measurements at or near the tropopause, where the quality

of remotely sensed data from both ground- and

space-based platforms is poor. If developed, a longendurance (multiple diurnal cycles) high-altitude UAV

would effectively become a geostationary satellite at

the tropopause. The tropopause is of particular interest

because it marks the vertical limit of most clouds and

storms. 46

The instruments on UAVS can be changed or

adjusted after each flight. UAVS are therefore potentially more responsive than satellite systems to new

directions in research or to scientific surprises. Scientists have also proposed using UAVS as platforms for

releasing dropsondes from high altitudes, a procedure

that would provide targeted measurements of climate

and chemistry variables at different altitudes in the

atmosphere.

UAVS would be especially important in calibrating

and interpreting satellite measurements. For example,

scientists have proposed using UAVS to measure the

angular distribution of solar and infrared radiation at

tropopause altitudes, which is necessary to estimate

flux and heating rates. Satellites are limited in their

capabilities to make these measurements because they

measure radiation from a limited number of angles.

Health and Environmental Research, 1993.

Currently, researchers using satellite data employ

elaborate models to reconstruct angular distributions

of radiation; limitations in the models remain a source

of fundamental uncertainty in Earth radiation budget

measurements. UAVS would both augment and complement satellite measurements of the effect of cloud

cover on the net radiation balance.47

High-altitude UAVS have a smaller payload capability than currently available piloted aircraft (table B-1 ).

However, they have several advantages that make

them particularly attractive for climate research:

●

●

●

UAVS under design should reach higher altitudes

than existing piloted aircraft. For example, the

ER-2 can reach the ozone layer at the poles, but

it cannot reach the higher-altitude ozone layer in

the mid- latitude and equatorial regions that

would be accessible to a UAV.

UAVS can be designed to have longer endurance

than piloted aircraft.

UAVS should have much lower operating costs

than piloted aircraft. For example, estimates of

direct and indirect costs for the piloted highaltitude ER-2 aircraft total some $15,000/hr of

flight. 48 UAV studies predict savings of an order

of magnitude or more.

~ k me ~opics, &e tropopause can reach altitudes of 18 km. Monitoring the tropopause with airborne platfOrmS therefOre re@res vticles

capable of reaching an altitude of some 20 km. NASA’s piloted ER-2 can reach this altitude, but it is restricted to flights of 6 hours.

A long duration UAV flying at or below the tropopause would facilitate measurements of two quantities of fundamental interest. One, the

angular distribution of radiatio~ is necessary for measurements of the Earth’s radiation budget, but is dtilcult to measure with satellit= (see

discussion below). The other, the flux divergence, can be related to the net heating that is ooauring in a particular laycx of the atmosphere. It

is a fundamental parameter that appears in globat circulation models of the Earth’s atmosphere and climate.

47 Satellites fly above tie Eti’s atmosph~e. A source of uncertainty in measurements of the effects Of clouds on the net rWhtiOII balance

is the relationship between the ‘‘top of the atmosphere’ infrared and solar fluxes observed by satellite and the fluxes at the tropopause, which

are the fundamental quantities of interest. See Peter Banks et al., op. cit., footnote 44, pp. 37-41.

a Estiates from James G. Anderso~ based in part on contract Costs frOm mkh~ COrP.
Appendix B—The Future of Earth Remote Sensing Technologies | 127

1993.

●

●

●

●

UAVS alleviate concerns about pilot safety on

flights through polar or ocean regions.

UAVS would be designed to fly at high altitudes

at subsonic speeds. Supersonic high-altitude aircraft like the SR-71 (cruise altitude over 80,000

feet) are not suitable for many in-situ experiments

because they disturb the atmosphere they are

sampling (for example, the chemical species

involved in ozone depletion).

UAVS do not have the flight restrictions of piloted

aircraft. For example, the ER-2 is restricted to

daytime flight.

The relatively low cost of UAVS compared to

piloted aircraft should translate into more research aircraft and greater availability.

Table B-2 summarizes the characteristics of existing

and proposed high-altitude UAVS. The altitude record

for a propeller-driven UAV (67,028 feet or 20.4 km) is

held by the Condor, a very large (200-foot wingspan,

20,000 pound) drone aircraft developed by Boeing for

the DoD. The Condor has the range and payload

capability to be useful to atmospheric scientists;

furthermore, proposals exist to extend its operating

ceiling to even higher altitudes (researchers would like

UAVS to fly at altitudes of some 80,000 feet; in fact,

NASA studies call for the design of aircraft capable of

reaching 100,000 feet) .49 However, Condor would be

an expensive vehicle to buy and adapt for scientific

resea.rch. so

Aurora Flight Sciences, a company founded in

1989, is developing low-cost, lightweight UAVS

specifically for the atmospheric science community

(box B-5). Closest to development is Perseus-A, a

high-altitude drone capable of carrying 50-100 kg

payloads to altitudes above 25 km. The first two

Perseus aircraft are scheduled for delivery to NASA in

1994 at a cost of approximately $1.5 -$1,7 million for

each Vehicle.51 NASA, foundations, and private investors have supplied funds to Aurora for this work.

Both NASA and DOE (in its ARM program) plan to

use UAVS for key experiments. In addition, the

development of sensors for UAVS relates closely to the

development of sensors appropriate for small satellites. Despite the potential of UAVs to enable measure49,,sub~o~c ~~e for High Altitude Re~cht “ NASA Tech Briefs, ARC-12822, Ames Researeh Center, Moffett Field, CA. The

diffkulty in designing a high-altitude subsonic aircraft is direetly related to the challenge of designing propulsion systems, wing structures with

suftlcient ML and heat rransfer systems appropriate for operation in the tenuous reaches of the upper atmosphere. The density of air falls off

rapidly with increasing altitude (an exponential decrease).

50 unofflcl~ indu~~ e~~tes provid~ to OTA sugg~t tit resto@ one Condor could cost $20 million and y~ly main~t2D(% COStS

would be severat rnitlion dollars or more.

51 NASA my exacix ~ option for a ~d vehicle, which ~@t lower tit ~c~t WSE. A~Ora Flight sciences COrp. is SUpply@ a n

existing ground station for use with Perseus A. Development of Perseus B is also proceeding at Aurora. It is being funded with internal monies

and several small grants, including one from the Nationat Science Foundation.
128 I Remote Sensing From Space

Box B-5 The Perseus Unpiloted

Aerospace Vehicle

Perseus A is designed to carry payloads of about 50

kg to altitudes of 30 km in support of stratospheric

research. Perseus A will carry liquid oxygen to support

combustion because air densities at 30 km are only

some 2 percent those of sea level.

Perseus B would trade altitude for payload mass

and flight duration. It would also replace the closedcycle engine design of Perseus A with a two-stage

turbocharged engine. This more complicated engine

avoids the payload penalty incurred by carrying

on-board oxidant and is the key to long endurance.

Perseus C would be designed for mid-latitude

meteorological research and be capable of carrying

100 kg payloads to altitudes of 12-15 km.

SOURCE: Perseus Payload User’s Guide, Aurora Flight Sciences

Corp., 1992.

ments crucial to the global change research program,

congressional support for civilian UAV development,

and associated instrumentation, has been meager and

may be inadequate to provide a robust UAV capability.52 If it wishes to encourage innovation in global

change research, Congress may wish to increase

funding for the development of UAVS specifically

designed for USGCRP missions. Because UAVS

could be highly cost effective, moderate funding

increases of only a few million dollars per year could

ultimately lead to a major increase in UAV availability

for research.

THE ROLE OF SMALL SATELLITES IN EARTH

OBSERVING PROGRAMS

“Small” satellites have been defined as costing

$100 million or less including spacecraft, instruments,

launch, and operations. As noted in ch. 5, NASA, DOE

and ARPA are examining small satellite systems for

three roles in the U.S. Global Change Research

Prograrn: 53 1) to address gaps in long-term monitoring

needs prior to the launch of EOS missions, 2) to

provide essential information to support process studies prior to, and complementary with, the restructured

EOS, and 3) to allow for innovative experiments to

demonstrate techniques that greatly improve the ability to monitor key variables or improve/speed up the

process studies.54

Small satellites have three advantages as complements to larger systems, First, they are characterized

by relatively low cost compared to larger satellites.55

This facilitates ‘risk taking’ and encourages technical

innovation. Small satellite proponents see this advantage as the key to enabling rapid, affordable augmentation and modernization of larger satellites. Second,

small satellite missions can be developed in only a few

years or less. Typically, development of a small

satellite avoids the potential problems associated with

managing the integration of multiple instruments on a

single platform. Shortening the time to launch would

add resilience to the satellite portion of the global

change research program, large parts of which are

frozen in development some 10 years before flight.

Third, flying only a small number of instruments per

satellite allows orbits to be optimized for a particular

set of measurements.56

52 For exmple, although the FY 93 USGCRP report to Congress gave strong support for a $10 million dollar new start by tie DOE to develop

a UAV program, tight budgets prevented its irnplemeatation. For further information, see Our Changing Planet: The FY 1993 U.S. Global

Change Research Program (Washington DC: National Science FoundatioxL 1992), p. 71.

53 SW Committ& on Earth and Environmental Sciences (CEES) of the Federal Coordinating Council for Science, Engineering, and

Technology, Report of the Small Climate Satellites Workshop (Washingto& DC: Office of Science and Technology Policy, May 1992).

w Report of the Smll C/imte Sate//ltes Workshop, pp. 20-21. In addition to these missions, researchers at tie Godtid ~ti~te for SPace

Studies have proposed using small satellites for long-term (decadal-scale) monitoring in a program that would complement EOS.

55 ~ey ~so wei@ 1ess ~d do not require as expensive a launcher. However, launch costs are Smd compared to other EOS cosB.

Mutti-instrument EOS AM and PM satellites, Landsat 6, Landsat 7, and proposed EOS facility instruments-LAWS, Sm and HIRIS----require

a launcher in the Atlas 2AS-class. Launch costs with an Atlas 2AS may be some $130 rnilliorL but this is 20 percent or less of total system

costs (which also includes ground segment costs).

M However, some missions r~uire nearly simultaneous measurements by instruments that cannot be packaged on a skgle Wteuite. ~ Ws

case, a larger platform carrying severat instruments may be desirable. Another option would be to attempt to fly small satellites in close

formation.

ST For a more detailed dis~ssion of this subject see V. Ramanathan, Bruce R. Barkstrom, and EdwiI_I Harrisor4 ‘ ‘Climate arid tie ~’s

Radiation Budget, ” Physics Today, vol. 42, No. 5, May 1989, pp. 22-32.
—

Appendix B—The Future of Earth Remote Sensing Technologies I 129

A SMALL SATELLITE “GA P-FILLER’ ’-CLOUDS

AND THE EARTH’S RADIATION BUDGET57

The effects of human activities on the planetary

energy balance are a principal focus of climate change

research. The Earth’s energy balance or ‘‘radiation

budget’ consists of incident sunlight, reflected sunlight (e.g., from the tops of clouds), and radiation

emitted back to space, primarily from the Earth’s

surface and atmosphere. The emitted radiation falls

predominantly in the infrared and far-infrared portion

of the electromagnetic spectrum, The radiation budget

is directly related to climate because the balance

between the absorbed solar energy and the emitted

energy determines the long-term average global temperature. In addition, the temporal and spatial variations of the radiation balance are linked to the global

circulation patterns of the atmosphere and the oceans. sg

Lack of knowledge concerning how changes in

cloud type and cover59affect the radiation budget is a

principal source of uncertainty in 1) predicting climate

changes associated with anthropogenic increases in

greenhouse gases; and 2) understanding past and

future climate changes caused by variations in solar

output or in the orbital characteristics of the Earth60

.

Scientists have monitored the Earth’s radiation

budget with spaceborne instrumentation since the

early 1960s.

61 The most precise measurements of the

radiation balance and the effects of clouds (box B-6)

were made with sensors that were part of the Earth

Radiation Budget Experiment (ERBE) (box B-7).

Iong-term measurements of the radiation budget

and related data are necessary to distinguish

between anthropogenic and naturally occurring

variations in Earth’s climate. Continuing measurements of Earth’s radiation budget, and the effect of

clouds and aerosols, are necessary to establish a

baseline that might guide future policy decisions.

58 Many coup]cd ocean.atmosphere-land interactions influence the radiation budget. For example, the intensity of radiation emitted from tie

land surface varies w]th surface temperature. However, surface temperature depends on such factors as the amount of incoming solar ra(iiation,

which is affected by atmospheric absorption and scattering (which can be altered by human induced greenhouse gas changes or by natural events

such as volcanic eruptions), and the effects of clouds. Surface temperature is also affected by surface moisture (because the surface cools by

evaporation), which in turn is affected by surface composition and the presence of surface vegetation. Cloud formation and distribution depend

on a host of coupled ocean-atmosphere-land processes.

59 ~e$e Chnges ~clude he d]s~bution and fractional cover over land and ocean, and changes in cloud ~ti~de, latitude! and ‘efl~tivitY.

~c optical reflectivity of’clouds is itself a sensitive function of the detailed internal structure of the cloud, for example, the size and distribution

of water droplets and Ice crystals.

~ Solm output has been Masured since 1978 and has fluc~ated by approximately (J. 1 percent. AS noted earlier, the Ed absorbs

approximately 240 watts\mz of solar energy. Based on correlation of measured irradiance changes with visible features on the Sun+ scientists

suspect that solar irradlance may \ ary by several tenths of a watt per century. Changes of Earth’s orbit (e.g., its eccentricity or the inclination

of its spin axis) occur on time scales ranging from approximately 20,000 to 100,000 years. Source: Johan Benson, ‘ ‘Face to Face, Interview

with James Hamew Aerospace America, April 1993, p, 6.

61 Andrew ~Meton, sa~elll~e Remote sensing In cli~f(~l(jgy (@Oca RatOn, FL: CRC Ress), pp. 206-209,
130 I Remote Sensing From Space

NASA plans to continue radiation budget measurements as part of EOS by flying radiation budget

sensors on the U.S./Japan

62 satellite and on the

AM-1 platform (the CERES instrument, a follow-on to

ERBS). TRMM and AM-1 are scheduled for launch in

1997 and 1998, respectively. NASA plans related

flights of SAGE,63 the stratospheric aerosol and gas

experiment, as part of EOS. NASA officials acknowledge the desirability of flying CERES and SAGE

missions before EOS flights in the late 1990s, both to

assure data continuity and to have instruments in place

before the next occurrence of El Nino-type events in

1995-1997 (see box B-8).& Researchers would also

like to have instruments in place to monitor climatechanging surprises such as the eruption of Mt.

Pinatubo. However, NASA has not identified sources

of funding for these missions.

Researchers attending OTA’S workshop on the

future of remote sensing technology stressed that, to be

useful, radiation budget sensor systems must have very

high-quality calibration, long-term stability, and fully

developed data processing systems. Similar concerns

govern the ACRIM mission (see box B-9). Measurements taken on successive satellites must also overlap

for a sufficient time period to allow the two systems to

be intercalibrated.

Sensor requirements of fine calibration and longterm stability can be understood intuitively by observing that the radiation balance is the difference between

large energy inputs and outputs. Therefore, relatively

small measurement or calibration errors in incoming or

outgoing radiation will lead to errors in the energy

balance that would mask evidence of an actual change.

Similarly, changes in the way raw data are converted

to radiation intensities could mask small changes in the

radiation balance.65

A small satellite that would include the CERES

instrument is among a number of small satellites being

62 TRMM, the tropicaJ rainfall measuring mission, will combine a NASA-supplied spacecraft with a Japanese launch vehicle. ‘Ihe payload

for TRMM will be supplied jointly.

63 SAGE I flew ~m Fe- 1979 to Nove~r 1981. SAGE ~ ~b-flying on & ERBS ~tefite SiIICC octo&r 1984, a period we~

beyond the instrument design life. Flights of SAGE III before the year 2000 were recommended by the Payload Advisory Panel of the EOS

Investigators’ Working Group in October 1992 because ‘SAGE has demonstrated that it can monitor consistently and overlong term several

parameters that are crucial to global change: a. vertical profiles of ozone, b. stratospheric and tropospheric aerosol loading, and c. water vapor

in the upper troposphere and lower stratosphere. The SAGE ozone measurements are now a key component of the present monitoring of the

changing stratospheric ozone; the aerosol measurements are crucial for assessing the variability of solar forcing to the climate system

consequent to the sporadic and highly variable volcanic aerosols. ” See Bernen Moore III and Jeff Dozier, “Adapting the Earth Observing

System to the Projected $8 Billion Budget: Recommendations from the EOS Investigators,” Oct. 14, 1992, unpublished document available

from authors or from NASA Office of Space Science and Applications, pp. 23-25.

1$1 ~her fli~ts of SAGE III on a ‘ ‘mission of opportunity” is advocated by EOS’ Payload Panel Advisory Group. One ~ch flight would

be on a planned NOAA weather satellite that could accommodate SAGE without necessitating expensive modiilcation of the bus or causing

signi.tlcant changes in the planned instrument package. NOAA’s ‘AM” TIROS series is a suitable candidate (it has a space where the SBW

sensor is placed for “PM’ flights); a 1997 launch might be possible if funding is identifkd. However, even if this gap-falling mission were

launched, sampling of diurnal variations would still be lacking because NOAA weather satellites fly in polar, sun-synchronous orbits. To fti

the potential gap in SAGE data and to supply data from inclined orbits, scientists have proposed flight of SAGE II on a planned 1995 Russian

launch. As of June 1993, NASA officials had not identi.fkd funding for either of these options.

65 Denv~g ~diation budget &~ 

from ~te~ite.~~ instrument measurements is till extremely COII@eX Prowss tit~iressophistic~~

models and computer programs. The steps involved in processing radiation data include:

. Convert instrument counts to radiant energy at detector.

. Unfiiter that signal to the froni end of the instrument (i.e., put back what was lost in the instrument’s optical path). This correction is scene

dependent.

. Convert to radiance at the top of the atmosphere.

. Convert radiance to flux using angulardirectional models.

Robert Cess, “Science Context of Small Globat Change Satellites or Perspectives From One Who Would Like To Have Satellite

Radiometric Data Before He Retires or Expires, ‘‘ in Paul V. Dreseler and Jack D. Fellows, cc-chairrnq Collected Viewgraphs: A Supplement

to the Reporr of the Smull Satellites Workshop, (Washington D.C.: Committee on Earth and Environmental Sciences, June 1992).
Appendix B—The Future of Earth Remote Sensing Technologies I 131

Box B-7–Earth Radiation Budget Experiment (ERBE)

ERBE (Earth Radiation Budget Experiment) is a NASA research instrument that consists of two parts. The

first is a relatively wide fixed field-of-view instrument with four Earth-viewing radiometers and a Sun-viewing

radiometer equipped with shutters. The Earth-viewing radiometers monitor outgoing Earth radiation in two bands:

0.2 to 5 microns (short-wave infrared) and 0,2 to 50 microns (broadband total). The second part of ERBE is a

narrow field-of-view (instantaneous field of view of approximately 3°) three-channel (0.2 to 50,0.2 to 5.0, and 5.0

to 50 micron) instrument that can be scanned. ERBE data allow an analysis of monthly and seasonal variations

of the radiation balance at regional scales. They also allow an analysis of the effect of clouds on the radiation

budget. As noted in the text, analysis of ERBE data to date has shown that the net effect of clouds is a small cooling

of the Earth. scientists are still unsure how the planetary energy balance will be affected by clouds in future

atmospheres that are likely to contain higher concentrations of greenhouse gases such as C02.

To monitor the Earth’s radiation budget properly, daily global data from two polar orbits (A.M. and P. M.) and

a mid-latitude inclined orbit of 50-60 degrees are required. ERBE sensors flew on the Earth Radiation Budget

Satellite (ERBS), which was launched by the Space Shuttle into a Iow-inclination, non-sun-synchronous orbit and

the NOAA 9 and NOAA 10 operational weather satellites, which are in sun-synchronous polar orbits. These were

launched in December 1984 and July 1986, respectively. Five years of data were collected before the last ERBE

scanner failed in 1990.1

1 Non-scanner measurements are continuing on the NOAA-9 and NOAA-10 and data are continuing to be archived.

However, the ability to characterize the scene covered by ERBS, which is crucial in radiation budget measurements, is

limited because the non-scanners have a relatively wide field-of-view. As a result, the data have limited utility compared

to the data that was being provided by the ERBS narrow field-of-view scanner.

SOURCE: National Aeronautics and Space Administration and Office of Technology Assessment, 1993,

considered for joint missions among NASA, DOE,66 discussed in ch. 5. The several decade record of

and DoD (through ARPA). (However, as noted earlier,

budget constraints and other difficulties have delayed

implementation of these proposals.) NASA officials

interviewed by OTA supported efforts by DOE and

DoD for collaboration because interagency cooperation may be the key to ensuring the long-term support

that is necessary for multidecadal missions such as

ERBS. In addition, harnessing the expertise resident in

DOE laboratories could accelerate the development of

technologies that promise to reduce mission costs.

CLIMSAT: A SMALL SATELLITE COMPLEMENT

TO EOS

The rationale for launching a series of small

environmental monitoring satellite*Climsat-was

high-quality data on CO2 abundance in the atmosphere

is a prototype for the kind of measurements that

Climsat would perform (figure B-3). CO2 change is a

key climate forcing variable. In addition, the historical

C O2 record provides an important constraint on

analyses of the carbon cycle and directs researchers to

the kind of detailed measurements needed to understand the observed CO2 change.67 In the same way,

Climsat’s long-term monitoring of other global forcings and feedbacks would help bound the thermal

energy cycle and direct researchers toward detailed

measurements of climate processes (some of these

measurements would be made in the EOS program).

~ ResWch grOUpS in the DOE have proposed to build and launch, by 1995, one or more small spacecraft equipped wi~ mdiation budget

instruments similar to those now flying on ERBS, or with what they believe would be an improved sensor. The improved sensor, which would

be designed by DOE, promises better capability in analyzing the spectral content of the received signals. DOE researchers believe their sensor

would therefore allow a better understanding of climate forcing from for example, COZ and water vapor. However, the importance of stibifity

in instrument calibration and data analysis argue for a cautious approach when comidering major departures from previous ERBE sensors.

67 J~es men, NASA Goddard Institute for Space Studies, peNOIEd communication, 1993.
132 I Remote Sensing From Space

Box B-8-The Linkage Among Earth’s Systems: El Nino and the Southern Oscillation

Coastal Peru is arid enough so that sun-baked mud is often used to build houses. In the

neighboring ocean, intense upwelling pumps nutrients tot he surface to create one of t he world’s richest

fisheries. In late 1982 the nutrient pump shutdown, eliminating the local fishery. And the rains began:

some normally arid zones received as muchas3m[118 inches] of rain within a 6 month period. Mud

houses dissolved, and much of the transportation infrastructure washed away. Almost 1,000 years ago,

a similar climatic disaster destroyed a prosperous agricultural civilization rivaling the Incas.

Peru was not alone: the impact of the strange climatic events of 1982-83 was global. In Indonesia,

vast areas of rainforest were destroyed in fires spawned by a devastating drought. Australia

experienced the worst drought in its recorded history: firestorms incinerated whole towns, livestock

herds had to be destroyed, and production of cotton, wheat, and rice was sharply reduced. In Brazil,

an exceptionally poor rainy season distressed the impoverished Nordeste region, while southern Brazil

and northern Argentina were hit with destructive flooding. Throughout southern Asia, poor monsoon

rains in 1982 reduced crop yields and slowed economic growth. China saw drought over the northern

part of the country and unusual winter floods in the south, leading to major losses in the winter wheat

crop. . . Severe winter storms rearranged the beaches of California; spring floods covered the streets

of Salt Lake City. . .

The above paragraphs describe events that occurred as a result of an irregularly recurring pattern known as

ENSO. The acronym combines its oceanographic manifestation in the eastern tropical Pacific, El Nino, with its

global atmospheric component, the Southern Oscillation. ENSO is an irregular cycle with extremes of variable

amplitude recurring every 2 to 7 years. The 1982-83 events are an instance of its warm phase. Events of 1988,

including catastrophic flooding of Bangladesh, demonstrate the impact of t he cold phase. Historically El Nino was

the name given to the marked warming of coastal waters off Ecuador and Peru. It is now understood that during

the ENSO warm phase the warming covers the equatorial Pacific from South America to the dateline, fully

one-quarter of the circumference of the Earth (plate 8).

SOURCE: Mark A. Cane, Geophysics Report E/Ninoandthe Southern Osci//ation (ENSO), Larnont-Ooherty Earth Observatory, Columbia

University,

Although Climsat is designed for long-term meas- . Short-term tests of climate models/understanding

urements, it would also address short-term issues.68 (e.g., effects of volcanic aerosols).

These include:

Each Climsat satellite would carry three instruments . Assessment of climate forcing resulting from (box B-10). Versions of two of these instruments, ozone change versus forcing that results from SAGE ILIG9 (Stratospheric Gas and Aerosol Experi- changes in CFC concentrations.

. Assessment of climate forcing resulting from ment) and EOSP (Earth Observing Seaming Polarimeanthropogenic tropospheric aerosol change ver- ter),

first sus CO2 change.

are part of the current plans for EOS. However,

launches of these instruments may not occur until

~ ~ese issues ~emong hose discussed in the Supplementary Report to the Intergovernmental Panel on Climate Change @CC) Scientific

Assessment (an update of the 1990 report). The IPCC supplementary report concludes that stratospheric ozone depletion may be offsetting much

of the greenhouse warming caused by CFCS. In additiow cooling by tropospheric aerosols from sulfur emissions may have offset a significant

part of the greenhouse warming in the northern hemisphere during the past several decades.

@ SAGE fJI is ~ improved version of SAGE II, now in orbit. It should increase the accuracy of aerosol, ozone, and water vapor

measurements. It should also permit extensions of these measurements deeper into the troposphere.
Appendix B—The Future of Earth Remote Sensing Technologies I 133

Figure B-3-Carbon Dioxide Concentrations

in the Atmosphere

380

300 ‘

1955 1965 1975 1985 1995

inclined orbit that drifts in diurnal phase. Having

SAGE III on both these satellites would provide global

coverage and allow researchers to sample diurnal

varaitions. 71 EOS might duplicate this coverage for

SAGE III, assuming SAGE III flies to inclined orbit on

a Pegasus in 2000 and to polar orbit on a multiinstrument platform around the year 2002. EOSP is

currently scheduled for inclusion only on the second

AM platform in (approximately) 2003.72

SAGE III was recommended for inclusion in EOS

principally because of its capability to make highaccuracy measurements of the vertical distribution of

ozone and stratospheric aerosols. These measurements

will be made in a geometry that allows SAGE III to

observe the sun or moon through the limb of the

Earth’s atmosphere. A dramatic example of the impact

of aerosols on Earth’s climate is the apparent global

cooling effect of the June 1991 eruption of Mt.

Pinatubo in the Philippines.73

EOSP measures the radiance and polarization of

sunlight reflected by the Earth in 12 spectral bands

from the near ultraviolet to the near infrared. Among

the principal objectives of EOSP are the global

measurement and characterization of tropospheric

aerosols, surface reflectance, and cloud properties

(e.g., cloud top height and cloud particle phase and

70 &ller fllghts of SAGE III on a ‘‘flight of opportunity ‘‘ is advocated by EOS Payload Panel Advisory Group. One such flight could be

on a plamed NOAA weather satellite that could accommodate SAGE without necessitating expensive modification of the bus or causing

significant changes in the planned instrument package. NOAA’s ‘ ‘AM’ TIROS series is a suitable candidate; a 1997 launch might be possible

if funding 1s available, However, even if this gap-filling mission were launched, sampling of diurnal variations would still be lacking because

NOAA weather satellites fly in polar, sun-synchronous orbits.

71 A Cllmat ~ a sun_sync~onousncm_wlM orbit would provide a fixed did reference. The second satellite would be placed into in a

processing orbit inclined 50-6072 to the equator. It would provide a statistical sample of diurnal variations at latitudes with significant diurml

change.

YZ An EOSp ~redwessor ~smments tit was Iauched on a fission to Venus allowed SClt?IItlStS tO derive v~uable dam on cloud and ‘e

characteristics and stmcture. However, the capability of EOSP to make similar measurements over Earth is complicated by Earth’s more varied

surface reflectivity and polarimtion characteristics, particularly over vegetated-covered land. As part of its plan to adapt EOS to funding of

$8 billion for 1991-2000, instead of$11 billion, NASA accepted the recommendation of its advisory group to delay EOSP until the second

AM platform in 2003.

Climsat supporters at the Goddard Institute for Space Studies argued against the delay in EOSP. Their reasons for believing EOSP could

make the required aerosol measurements were based on both experimental and theoretical studies. These studies are detailed in J. Hansen, W.

Rossow, and I. Fung, “Long-Term Monitoring of Global Climate Forcings and Feedbacks,” Proceedings of a Workshop held at NASA

Goddard Institute for Space Studies, Feb. 3-4, 1992, pp. 4&47.

73 The Plme from the emption deposited great quantities of gases (e.g., SOZ) and ash hto the smatosphere where they pmduc~ oPti~lY

significant quantities of aerosols that are expected to remain for several years. (Photochemical reactions convert the S02 to sufic acid, H2SOA,

which subsequently condenses to form a mist of sulfuric acid solution droplets. Sulfate aerosol is a mixture of sulfiuic acid and water). Beeause

of their small sti.e, these aerosols are more effective at reflecting shortwave solar radiation than they are at attenuating the longer wavelength

thermat radiation emitted by the Earth. Thus, the aerosols alter the Earth’s radiation balance by reflecting more of sun’s energy back to space

while permitting the Earth to COOI radiatively at approximately the same rate as before the eruption. The result is a net loss of energy for the

Earth atmosphere system, or a cooling of the atmosphere and surface. See P. Minnis et. al., ‘‘Radiative Climate Forcing by the Mount Pinatubo

Eruption, ” Science, vol. 259, No. 5100, Mar. 5, 1993, pp. 1411-1415.
134 I Remote Sensing From Space

Box B-9-Why Remote Sensing Places Particular Demands on Instrument

Calibration and Stability

Much of global change research consists of establishing long-term records that will allow anthropogenic

changes to be distinguished against a background of naturally occurring fluctuations. Therefore, measurements

must be finely calibrated, instruments must have long-term stability, and data reduction and analysis algorithms

must be well understood. Measurements of the Earth’s radiation budget illustrate these requirements. Another

example of the need for finely calibrated data in global change research is provided by the ACRIM (active cavity

radiometer irradiance monitor) instrument to monitor long-term changes in the total solar output. This instrument

is currently not on the EOS flight manifest, but NASA officials have stated their desire to fly ACRIM on a “flight of

opportunity.”

The interaction of the Earth and its atmosphere with the total optical solar radiation from the sun determines

weather and climate. Even small variations in the total solar output would have profound effects on both weather

and climate if they persisted. Scientific evidence exists for past climate changes, including cyclic changes ranging

in period from the approximate 11-year solar activity cycle to many millions of years. Variations in solar output are

suspected as the cause of some cycles, particularly short-term ones.

Acquiring an experimental database on solar variability is a necessary first step in testing hypotheses about

how solar variability might affect climate. It is also necessary if researchers are to distinguish variations in solar

output from other climate “forcings” such as changes in concentration and vertical distribution of infrared trapping

“greenhouse” gases, aerosols, and clouds. Previous ACRIM measurements, beginning with the “Solar Maximum

Mission” in 1980, have shown that solar luminosity varies with solar activity during the n-year solar cycle.

Researchers would Iike to extend the ACRIM record base begun in the 1980 as part of the Earth radiation budget

database for the Global Change Research Program. They would especially Iike to avoid gaps between successive

ACRIM missions to “connect” (calibrate) readings between successive instruments and facilitate detection of

subtle changes.

In his proposal for launching a new ACRIM mission before the mid-1990s,l Richard C. Willson, of the Jet

Propulsion Laboratory, cites estimates that all the climate variations known to have occurred in the past, from major

ice ages to global tropical conditions, could be produced by systematic solar variability of as little as 0.5 percent

per century. Because the results of many solar irradiance experiments would be required to monitor the solar

Iuminosity for 100 years, the relative precision of successive experiments would have to be small compared to O.5

percent.

Researchers have adopted an overlap strategy that would deploy successive ACRIM experiments so that

overlapping observation periods of approximately 1 year can be used to provide relative calibration of the data at

a precision level (0.00I% of the total irradiance) that is substantially smaller than their inherent uncertainty (0.1%).

Although continuous data on solar luminosity has not existed long enough to detect the presence of sustained solar

luminosity changes that might have climate implications, the long-term precision required to detect such a trend

would considerably exceed 0.1 percent.

1 NASA ~ans to fly ACRIM on EOS flights starting around the year 2002, but a potential gap in measur~ents

exists for the approximate period of 1994-2002. The only ACRIM sensor now in orbit is on UARS, a satellite whose useful

Iifeis expsctedto end In 1994. UARS might exceed Its design life, but recent problems with its battery povversuppliesalso

serve as a reminder that satellites can suffer premature failure.

SOURCES: Office of TAnology /keeeernent and Richard C. Willeon, “Science Objective of an Active Cavity Radiometer Irradiance

Monitor (ACRIM) Experiment on a Dedicated Small Satellite System,” in Committee on Earth and Environmental Sciences (CEES) of the

Federal Coordinating Coundl for Science, Engheedng, and Technology, I?epoft of the Sma//C/hnate Satellites )Wrkshop (Washington,

DC: Office of Sdenoe and Technology Policy, May 1992).
Appendix B—The Future of Earth Remote Sensing Technologies I 135

Box B-10-Climsat Sensor Summary

SAGE Ill (Stratospheric Gas and Aerosol Experiment): an Earth-limb scanning grating spectrometer that

would be sensitive from t he ultraviolet to the near infrared. Yields profiles of tropospherc aerosols,O3N02

,H2O

OCIO-most down to aloud tops. Instrument mass: 35 kg; Power (mean/peak): 10/45 watts; Estimated Cost: $34

million for 3 EOS copies ($18M + $8M + $8 M).

EOSP (Earth Observing Scanning Polarimeter): global maps of radiance and polarization; 12 bands from near

UV to near IR. Yields information on aerosol optical depth (a measure of aerosol abundance), particle size and

refractive index, cloud optical depth and particle size, and surface reflectance and polarization. Instrument mass:

19 kg; Power (mean/peak): 15/22 watts; Estimated Cost: $28 million for 3 EOS copies ($16M + $6M + $6M).

MINT (Michelson Interferometer): Infrared measurements between 6 and 40 microns. Yields cloud

temperature, optical depth, particle size and phase, temperature, water vapor, and ozone profiles and surface

emissivity. Instrument mass: 20 kg; Power (mean/peak): 14/22 watts; Estimated Cost: $15-$20 million for first copy.

SOURCE: J. Hansen, W. Rossow, and 1. Fung, “Long-Twin Monitoring of Global Climate Forcings and Feedbacks,” Proceedings of a

Workshop held at NASA Goddard Institute for Space Studies, Feb. 3-4,1992.

size). Characterization of clouds and aerosols is science missions, including EOS and the Mission to

necessary for both climate models and to interpret

signals received by satellite from the Earth’s surface

(e.g., by AVHRR and Landsat). For example, aerosols

affect the transmission of electromagnetic radiation

through the atmosphere and the clouds, but they are

currently among the most uncertain of global climate

forcings. Cloud cover and aerosol content are highly

variable; like SAGE III, the argument for launching

these instruments as part of Climsat, rather than EOS,

is the additional coverage and better sampling of

diurnal variations.

MINT (Michelson Interferometer) is the only

Climsat instrument that is currently not scheduled for

inclusion in EOS. MINT would measure the infrared

emission from the Earth at high spectral resolution

over a broad spectral range. Its principal measurement

objectives include cloud temperature, transrnissivity,

particle size and phase (water or ice); temperature,

water vapor, and ozone vertical profiles; and surface

emissivity.

| Developing Advanced Systems for

Remote Sensing

The final section of this appendix draws on comments by participants at an OTA workshop on the

future of remote sensing technology and briefings

from scientists at NASA, DOE national laboratories,

and industry.

NASA has identified a variety of high-priority

technologies needed to enable or enhance future space

Planet Earth (box B-1 1). NASA’s most urgent shortterm technology requirements are for more sensitive

long-wave infrared detectors, reliable cryogenic cooling systems, and development of submillirneter and

terahertz microwave technologies. Mid-term requirements include new lasers, improved onboard data

storage systems, and development of larger antenna

structures. Long-term requirements, which are considered very important for the success of MTPE, include

improvements in software and data analysis and in

power systems. Improvements in software and data

analysis are critical to the success of EOS because

scientists need to convert the raw data to information. Accumulating data is not equivalent to solving

problems.

Participants of OTA’S workshop on the future of

remote sensing technology generally agreed that

existing and planned efforts in technology development at the component level were sufficient to develop

next-generation sensors. However, several participants

expressed concern about the lack of commitment and

funds to perform required engineering, integration, and

prototyping of integrated, space-qualified sensors.

This work is essential if the size, weight, and cost of

space-based sensors is to decrease. Such efforts are

particularly important for the large EOS “facility”

instruments that were deferred or canceled-LAWS,

SAR, and HIRIS. (One participant characterized the

kind of development work that is necessary to develop
136 I Remote Sensing From Space

Box B-11–Technology For Mission To Planet Earth

Direct Detectors

The particular need is for detectors capable of monitoring the interaction of the long-wave infrared thermal

emission from the Earth with greenhouse gases-this requires detection of far-infrared photons in the 8 to 20

micron range.

Cryogenic Systems

Cryogenic coolers are needed to increase the sensitivity of infrared radiation detectors, particularly at long

wavelengths. Stored cryogens (e.g., liquid nitrogen) are not suitable for long-duration missions. Passive radiative

coolers, which area mature technology, cannot be employed when extremely low temperatures are required or

when there are geometric limitations (a passive cooler requires a large surface that never absorbs energy from

the sun).

Mechanical cryo-coolers are miniature refrigerators. NASA plans to use tens of mechanical coolers during

the 15-year EOS program. Concerns about their use include: their long-term reliability in a space environment; how

to damp vibrations (NASA currently favors employing two matched cryo-coolers in a configuration where the

vibrations of one cancel the other’s); how to increase the efficiency of coolers (to provide sufficient cooling power);

and how to reduce the cost of developing space-qualified units, which is currently measured in the million dollar

range.

Submillimeter and Terahertz Microwave Technologies

The millimeter, sub-millimater (frequencies above 300 GHz) and terahertz region of the microwave is of

interest because this is the region where small, light molecules and free radicals of fundamental importance in t he

chemistry of the upper atmosphere can be monitored via their strong rotational emissions. Monitoring in this region

also complements other techniques. For example, measurements taken with millimeter/sub-millimeter techniques

are not affected by changes in aerosol or dust concentrations in the atmosphere (because the wavelengths are

larger than the dust or aerosol particle size). In contrast, optical or ultraviolet measurements are strongly affected

by aerosol and dust loading and therefore are sensitive to changes that resulted from the eruption of Mt. Pinatubo.

Using techniques that are common to ground-based radio astronomy, researchers can analyze the strength and

spectral width of molecular line shapes to determine the altitude and temperature distribution of molecules and

radicals such as CIO, water vapor, nitrous oxide (N20), CO, and H02

.’

Historically, sources and detectors for this region of the electromagnetic spectrum have been notoriously

difficult to develop. At lower frequencies, up through the millimeter wave region, conventional klystrons and

multiplication techniques may be used. Optically pumped far-infrared lasers provide a source of energy at higher

frequencies, but only at a relatively few discrete laser frequencies.

Lasers

As noted earlier, development of a space-qualified high-power laser would allow the measurement of global

wind velocities. it would also be a powerful method to identify and measure concentrations and vertical profiles

1 Mol~ules are “excited” to higher energy states following collisions with other gas species. Emission of energy

oocurs when the molecule “relaxes” back to its normal energy state. The strength of the emission is a function of molecular

abundance. In addition, beoause of “pressure broadening,” the spectral w“dth of the emission contains information on the

altitude distribution of the emitting molecule (pressure broadening occurs for molecules of Interest at altitudes at pressures

correspmding to altitudes below 70 km). See, for example, Alan Parrish, “Millimeter-wave Environmental Remote Sensing

of Earth’s Atmosphere,” Microwave Journal, vol. 35, No. 12, Dec. 1992, pp. 24-34.
Appendix B—The Future of Earth Remote Sensing Technologies I 137

of trace gases in the troposphere and stratosphere. In addition, it would allow accurate global measurements of

altitudes and land surface elevations from space. Current research centers on the demonstration of reliability of

COZ gas lasers and development of alternative solid-state lasers. Solid-state lasers require a laser “pump” to

excite the upper energy level involved in laser action. Current research is focused on the development of

diode-laser pumps because of their inherent reliability and energy efficiency.

LAWS is an example of a Iidar (light detection and ranging, i.e., laser-based radar). New lasers are needed

for Iidars and for DIAL (differential absorption Iidar). Important molecular atmospheric species such as oxygen,

water, and trace species such as nitric oxide (NO) and the hydroxyl radical (OH) can be measured with great

sensitivity using DIAL. Atmospheric temperatures and pressure can also be determined from an analysis of the

molecular absorption line width and strength. Laser measurements of molecular absorption bands for species

require tunable sources with extremely high frequency stability. For global use, systems must also operate at

eye-safe levels or in eye-safe spectral regions. As mentioned earlier, laser velocimetry can be performed using

either coherent or novel incoherent techniques. All of these issues are being explored in very active programs at

DOE and NASA laboratories.

Onboard Data Storage Systems

EOS spacecraft will acquire enormous quantities of data. Onboard storage is necessary to manage these

data-either to store data until satellite downlinks to Earth ground stations are available later in t he orbit, or to

facilitate data manipulation/compression to Iower the required communication data rate to Earth. For example, the

EOS AM-1 platform will acquire data at some 100 million bits/second (peak) and 16 million bits/second (average).

Output of data at peak rates up to 150 million bits/second will occur when AM-1 is in contact with the TDRS satellite

communications relay.

Near-term plans call for digital tape recorders to be used in EOS; however, the requirements of EOS

spacecraft will push the limits of tape recorder technology. Current research is focused on developing alternative

space-qualified storage systems, which would be smaller, lighter, more reliable (tape recorders have many moving

parts), and better matched to the data requirements. Concepts under development include solid-state memories

and optical disk technology.

Large Antenna Structures

Large lightweight antennas would facilitate development of affordable SARS.

Improvements in Software and Data Analysis

If current plans continue, the fully deployed EOS system of polar orbiters and other spacecraft are expected

to acquire some 1-2 trillion bits of data each day. Storing these data and translating them into useful information

in a timely manner is critical to the success of EOS. The SEASAT spacecraft (which included a SAR) operated

for only three months in 1978, but scientists took eight years to analyze the data. A sizable fraction of the total EOS

cost (currently at $8 billion for this decade) is earmarked to solving the myriad of problems associated with data

acquisition, analysis, and dissemination. OTA plans to publish a report on EOS data issues in late 1993.

Power Systems

Development of lighter weight and more energetic power systems would have a number of applications. In

particular, when combined with lightweight, large antenna structures, the possibility exists for placing radar

systems in higher orbits. Ultimately, researchers would like to place systems in gee-stationary orbit. Large

antennas would be needed because the beam size on the Earth is inversely proportional to antenna size.

SOURCE: OTA and Robert Rosen and Gordon 1. Johnston, “Advanced Technologies to Support Earth Orbiting Systems,” paper

IAF-92-0751, presented at the 43rd Cong. of the International Astronomical Federation, Aug. 25-Sept. 5, 1992, Washington, DC.
138 I Remote Sensing From Space

Box B-12–ARPA Space Technology Initiatives in Remote Sensing

ARPA’s Advanced Systems Technology Office has proposed several advanced technology demonstration

(ATDs) that might point to remedies for key problems in the development of future space systems: lack of

affordability, long development times, and high technical risk. ARPA program managers note that “our current

practice is to custom-build large satellites on roughly 10-year cycles. To avoid unacceptable program risk, only

proven or space-qualified technologies are typically incorporated. These technologies become obsolete even

before the first satellite is launched ...”

Two ARPA ATDs have particular interest to the civilian remote sensing community: the Advanced Technology

Standard Satellite Bus (ATSSB) and the Collaboration on Advanced Multispectral Earth Observation (CAMEO).

ATSSB would be characterized by very high payload mass fraction and a simplified payload interface (“bolt-on”)

that would support a wide variety of missions while minimizing acquisition times and recurring costs. CAMEO is

a proposal for a joint DoD/DOE/NASA collaboration to design, build, and launch a satellite using ATSSB that would

carry instruments of interest to both civil and military users.

CAMEO would demonstrate the utility of smaller satellites to rapidly insert technology and shorten

development time for larger satellites. It would carry three instruments:

. CERES, a NASA-developed instrument for aloud and Earth radiation budget measurements. CERES is

an approved EOS instrument scheduled for launch in the late 1990s. Earlier versions of the CAMEO

proposal considered a higher performance, but unproved, las Alamos-designed radiometer.

● MPIR, a DOE-developed, very wide-field of view (90 degrees; swath width at nadir for nominal orbit altitude

of 700 km is 1,000 km), pushbroom multispectral imaging radiometer. MPIR’s principal objective would be

to gather data for global change research, primarily aloud properties (e.g., cloud detection, identification,

type, amount height, reflectance, optical thickness, and internal characteristics such as particle size and

phase). Its 10 spectral bands would measure reflected sunlight and thermal emission from the Earth at

visible/near-infrared to long-wave infrared wavelengths from 0.55-12 microns. Because MPIR’s primary

mission is measurement of cloud properties, high resolution is not necessary. The baseline proposal calls

for a ground resolution of 2 km at nadir. MPIR would cool its medium-wave and long-wave infrared

detectors to 60 K with an 600-milliwatt Stirling-cycle mechanical cooler. MPIR would be small (it would fit

in a box 20 cm X 20 cm X 36 cm) and lightweight (25 kg). Its size and weight would also make it suitable

for a flight on a UAV.

lasers for LAWS and SAR as “somewhere between Workshop participants agreed unanimously that this

exploratory and advanced development.”)

Several researchers interviewed by OTA believed

the lack of attention to engineering development was

symptomatic of a larger problem: government interest

and investment typically wane as a technology becomes more mature. However, schedule slips and cost

overruns that occur during the final stages of instrument/

platform development might be avoided by making a

greater investment earlier in the development cycle,

even if it is for what maybe perceived as lower priority

engineering problems.

Currently, the time required between preliminary

design and launch for a new, large, and complex

satellite system may stretch to nearly a decade.

period must be reduced for remote sensing systems.

Similarly, workshop participants stressed the importance of reducing space mission costs. Unfortunately,

the space community has not reached consensus on

how best to achieve these goals. Box B-12 discusses

ARPA’s belief that space missions can be carried out

with lower costs and shortened acquisition times by

developing small satellites that would employ a small

common satellite bus featuring standardized payloadbus interfaces. In particular, ARPA has proposed a

joint collaboration among NASA, DOE, and ARPA to

build and fly a gap-filling satellite to collect data for

Earth radiation budget experiments. This satellite

would also demonstrate technology applicable to
Appendix B—The Future of Earth Remote Sensing Technologies I 139

. LMIS, a DARPA-sponsored narrow field-of-view, high-resolution multispectral imager. LMIS would use

pushbroom image formation and have a mechanically cooled focal plane. Notable among its

characteristics is its hyperspectral imaging (32 bands) in visible/near-infrared bands. Other spectral bands

would image the Earth in visible, short-, and medium-wave infrared. Resolutions would range from 2.5

meters in the panchromatic band to 20 meters in the medium-wave infrared. LMIS’ swath width at nadir

would be 20 km.

CAMEO’s flight of CERES would avoid a likely gap in Earth radiation budget measurements while LMIS and

ATSSB would demonstrate technologies for advanced imaging satellites. In particular, ARPA hopes LMIS and

ATSSB would facilitate follow-ons in the Landsat series that would be lighter, smaller, less expensive, and

incorporate a greater number of spectral bands. However, realizing all of these objectives in an imaging system

similar to Landsat is likely to prove difficult, even if the CAMEO demonstration proved successful. For example,

although the Thematic Mapper on Landsat 6 and Landsat 7 have fewer bands and somewhat lower ground

resolution than proposed for LMIS, they also have a much larger swath width (165 km versus LMIS’ 20 km).

Whether it will possible to develop a LMIS-type instrument with a wider field-of-view is one of many technical

challenges. An ancillary issue t hat affects CAMEO and other proposed multispectral and hyperspectral imaging

satellites is how best to use the added spectral information. Researchers in the satellite-based HIRIS program and

in the aircraft-based HYDICE program are still at a relatively early stage in determining the capabilities of

hyperspectral imaging.

ARPA’s ATDs were fully supported by the DoD, but were severely cut by the Senate Appropriations Defense

Subcommittee staff. The programs have been restructured for a fiscal year 1994 start and include an added new

emphasis on the potential benefits of CAMEO in enabling the United States to develop and greatly expand its role

in future commercial remote sensing markets.

SOURCE: Advanesd Research Projeets Ageney, 1993.

follow-ons in the Landsat series and to global change As noted in chapter 2, the projected annual shortfall

research. Other proposals for small satellites and

lightweight remote sensing instruments have been

advanced by the DOE national laboratories (box

B-13).

In an era of level or declining budgets, cost, not

technology, may be the most important factor in

determining which new remote sensing projects to

fund.74 However, even without the pressure induced

by recent budget cutbacks, programs that hope to

address the fundamental questions associated with

global change research in a timely manner will still

have to evolve in the direction of “smaller, faster,

better, cheaper.” Shorter project development periods and lower costs would better match the period over

which scientific understanding improves, technology

advances, and changes occur in the Earth systems

under study.

between NASA’s planned activities and appropriations may increase throughout the decade. With

multibillion dollar shortfalls, new development efforts

for remote sensing technologies may be curtailed in an

effort to maintain ongoing programs. Given this

reality, one OTA Advisory Panel member suggested

that NASA should institute a process to phase out

approximately 15 percent of the base program per year

to make room for innovation and new scientific/

technical directions. This panel member further noted

that because the current management approach is to

key new ideas to budget appropriations, “new ideas

rarely see the light of day. ’

Other researchers interviewed by OTA agreed that

lack of funding for some programs might stifle future

innovation in the future, but disagreed with the

assessment that a problem currently exists. They

74 ~s view is widely held; see, for example, Dean Freer, ‘‘Using Today’s Strategic Defense Initiative (SDI) Technologies to Accomplish

Tomorrow’s hw Cost Space Missions, ” IAF-92-0752, paper presented at 43rd World Space Congress, Aug. 31, 1992, Washingto~ D.C.
140 I Remote Sensing From Space

Box B-13-DOE Multispectral and Hyperspectral Imaging Systems

The Department of Energy is developing a variety of multispectral instruments for launch on small satellites

to support ongoing efforts in global change research and to demonstrate technologies for nuclear proliferation

monitoring. DOE’s multispectral pushbroom imaging radiometer-MPIR-was discussed in box B-12. This box

summarizes characteristics of two other proposed DOE instruments: SiMS-small imaging multispectral

spectrometer (formerly denoted as “mini-HIRlS”) and the MT1-multispectral thermal imager.

The SIMS spectrometer is a joint NASA-DOE technology project to demonstrate that a small, lightweight

instrument can obtain high spectral resolution images of modest spatial resolution that would be useful for global

change research and non-proliferation missions. SIMS would have two grating spectrometers. It would operate

in 5 nm contiguous bands from 0.4-1 micron and from 1-2.5 micron. SIMS would employ a 10 cm diameter

telescope; its spatial resolution in the various bands would be 80-100 meters from its nominal orbit altitude of 700

km.1 AS noted in earlier discussions of HIRIS, hyperspectral imaging with even modest spatial resolution can

translate into enormous data rate and storage requirements. A 20 km X 20 km SIMS image would contain some

100 trillion bits. Data rate and storage requirements can be reduced, however, by selecting only a small subset

of spectral channels for each scene.

The Multispectral Thermal Imager (MTl) is, in effect, DOE’s version of ARPA’s LMIS instrument (box B-1 1).

MTI is a technology demonstration that is jointly sponsored by DOE’s Sandia National Laboratory, Los Alamos

National Laboratory, and Savannah River Technology Center. Its objectives are to collect high spatial resolution

multi-spectral and thermal images for proliferation monitoring and to demonstrate technology applicable for future

Landsats. However, in contrast to ARPA’s proposal for CAMEO, MTI’s development will not be tied to the

development of a new standardized bus.

MTI would operate from 0.4-12 microns in 18 spectral bands. The instrument would fly in a nominal orbit

altitude of 500 km with a 0.35 meter diameter telescope. Its spatial resolution would range from 5 meters in the

0.4-1 micron (VNIR) to 40 meters in the 8-12 micron band (LWIR). A separate Iinear array would be used for each

spectral channel on a common focal plane assembly that would be cooled to 80 K with Stirling-cycle mechanical

coolers.

noted, for example, that innovation and new scientific fourth groupings might be satisfied by advanced

or technical directions have emerged out of existing

efforts by several agencies, notably in the discovery

and investigation of the Antarctic ozone hole. Furthermore, they believed that competitive peer review of

grant proposals to agencies such as the National

Science Foundation insured turnover in base programs.

| Developing Follow-ons in Landsat Series

User requirements for surface remote sensing data

can be grouped in four broad categories as shown in

table B-3. The first grouping of requirements will be

satisfied by the EOS system; the second grouping is

satisfied by the current Landsat; and the third and

Landsats. -

Landsat 5 was launched in March 1984. It has

greatly exceeded its planned operational life and will

be replaced by LandSat 6 in late 1993. Landsat 6 is

similar in most respects to Landsat 5, differing most

noticeably in its incorporation of an enhanced Thematic Mapper (TM) (table 4-1 ). The enhanced features

of Landsat 6 include the addition of a 15-meter

panchromatic (black and white) band, which can be

used as a ‘‘sharpening’ band for the 30-meter

multispectral imagery and improved band-to-band

registration (i.e., how well the same scene is recorded

in different spectral bands). Landsat 7, scheduled for

launch in the 4th quarter of 1997, would be the first
Appendix B—The Future of Earth Remote Sensing Technologies I 141

An example of a proliferation application for MTI would be to detect, monitor, and characterize the thermal

signature from a nuclear reactor’s cooling pond. This requires an infrared detection system that has relatively high

spatial resolution. Other applications are noted below.

Nuclear Facility Monitoring Objectives

. Relevant Objectives

detect/identify proliferators as early in cycle as possible

-assess =capabilities: test or use?

. Production Reactor

-thermal power and duty cycle

-total burnup

-fuel cycle technology

. Nuclear Material Processing/Reprocessing Plant

-plant identification

-process type

-capacity

—throughput

● Enrichment Plant

-plant identification

-process identification and capacity

—throughput and duty cycle

● Nuclear Device Fabrication/Storage Facility

-facility identification

-material fabricated and duty cycle

—storage area identification and location

1 Ireasing the resolution to 30 meters, the resolution of Landsat 5, would require increasing the aperture by

approximately a factor of 10.

2 SOURCE:Los Alamos National Laboratory, Space Science and Technology Division.

Landsat to incorporate stereo (table 4-2); it would also tral bands or provide a method to reconstruct older

have higher resolution than Landsat 6. 75 Landsat data in software. This is possible using

The first opportunity to depart from the current existing technology. (This assumes that an examinaevolutionary approach to Landsat improvements will tion of Landsat data concludes that the original bands

occur in Landsat 8, which, if approved, might be chosen for Landsat are still the most useful for Earth

launched some five years after Landsat 7. Develop- observation. Another option would be to discard some

ment of advanced Landsats presents familiar aspects of bands and retain only the several that are considered

the debate over how to guarantee 1ong-term continuity most important for continuity).

of measurements in an operational system, while still A more contentious issue centers on sensor design

allowing for technical innovation. Because much of for Landsat 8 and beyond. The design of Landsat’s

the value of Landsat for monitoring global change lies detectors requires compromises and tradeoffs among

in its ability to collect comparable data over time, spatial, spectral, and radiometric resolutions. Competfollow-on systems must either include existing spec- ing sensor concepts differ in their choice of optics

75 me H1~h Resolution Mulllspcctra] stereo Im~ger (HRMSI), if funded, would have a ground resolution of 5 mCtcrS in tie pmc~omatic

band and 10-meter resolution in the new-infrared bands, This is a three-fold improvement over Landsat 6, The Enhanced Thematic Mapper

(ETM+) planned for Landsat 7 also incorporates some improvements over the ETM for Landsat 6.
142 I Remote Sensing From Space

Table B-3-Surface Data Requirements

1. Wide-field, low-moderate spatial resolution

. Global land survey

. Global ocean survey

2. Medium-field, moderate-high spatial resolution

. Synoptic regional coverage

● Landsat user commmunity

3. Narrow-field, high spatial resolution, stereo

● Terrain elevation

● Perspective views, flight simulation

4. Narrow-field, high spatial and spectral resolution

● Custom-tailored data acquisition

. Application specific

SOURCE: A.M. Mike and C. F. schueler, “Landsat Sensor Technology,” Briefing to OTA at Hughes Santa Barbara Research Center,

January 1992.

(narrow or wide-field), scanning approach, and detector focal plane. Figure B-4 depicts the different

approaches (note, direction of satellite is indicated by

large arrow).

The simplest detector concept is to use a single

detector for each spectral band. This is the approach

used in NOAA’s AVHRR. Landsat uses several

detectors per band along the satellite track and scans

these detectors (using a mirror) simultaneously across

the satellite track. The scan rate is relatively high, but

still much slower than if only a single detector had

been used. NASA used this type of detector on the

multispectral sensor (MSS) on Landsat 1-5, and also

on the Thematic Mapper on Landsat 4 and Landsat 5.

It will also be used on the enhanced TM on Landsat 6.

A simple detector array has several advantages. In

particular, calibration of the sensor is relatively easy

because only a few electronic channels need to be

compared, and optics with a narrow field-of-view may

be used because they image only across a short array.

The principal disadvantage of this detection scheme is

its limited ‘‘dwell time’ (the time the detector is

gathering signal from a particular location on the

Earth). The limited dwell time restricts the signal-tonoise ratio at the detector and also requires ‘‘fast’

detectors and associated electronics (i.e., detectors and

electronics with high temporal frequency response).

Small detector arrays also require scanning mirrors.

While scanning mirrors have proved robust, a system

without a mechanical seaming system would be more

reliable and come closer to the ideal of a detector that

had only small numbers of electronic components and

no moving parts.

The “pushbroom” detector concept, which has

already been demonstrated on SPOT and on JERS-1,

has been proposed for future Landsats. In the

pushbroom concept, wide-field optics image a onedimensional line image of the Earth onto a large linear

array of detectors. The motion of the pushbroom along

the satellite track generates a series of one-dimensional

images, which are then added together electronically to

form a two-dimensional image. Several advantages

follow, principally that the scan rate is now slowed

down (to that provided by the motion of the satellite

moving in orbit+ .75 km/s for a satellite in orbit at

700 km). This greatly increases the time the detector

“sees” the image, which results in a larger signal and

therefore allows either greater spatial resolution or

finer spectral resolution. The pushbroom concept also

allows designers to craft a smaller, lighter instrument.

Finally, the reliability of the pushbroom should be high

because it doesn’t use mechanical cross-track scanning,

The pushbroom design has two principal drawbacks. First, it requires much longer detector arrays,

which have many more elements and are therefore

more difficult and expensive to manufacture and

calibrate (the number of detector elements for

pushbroom linear arrays might number on the order of

10,000). Second, it requires optics with a wide

field-of-view to obtain the same swath width as for the

corresponding seamer. Pushbrooms were not chosen

for Landsat 7 because the requirement for a 185 km

swath width would have forced designers to use wide

field-of-view optics. The SPOT satellite, which uses a

pushbroom, avoids some of the difficulties of developing wide-field optics because its swath width is only 60

kilometers.

Pushbroom scanners are being considered for Landsat 8. A more ambitious proposal would replace the

linear detector array of the pushbroom with a large

two-dimensional detector array and use a‘ step-stare’

imaging scheme. A step-stare system would use image

motion compensation to allow the array to stare at a

particular patch on the ground as the satellite moves

forward. The array would then be stepped to a new

location and held again until it had imaged all the way

across track. The advantages of this system are

increased dwell time and necessity for only moderate
Focal

plane

Appendix B—The Future of Earth Remote Sensing Technologies I 143

Figure B-4-Surface Optical Remote Sensing Techniques

“Whisk-broom”

Serial Parallel

cross-track cross-track

<

Low-earth orbit

6.75 km/see ground velocity

—

Cross-track High

scan speed

Motion Continuous

Multiple

detectors

per band

Medium

Oscillatory

Linear Two-dimensional

array for array for

each band each band

Zero Medium

SOURCE: Hughes Santa Barbara Research Center Briefing Charts, 1992.

field-of-view optics. Its disadvantages are a larger and

more complex focal plane than the pushbroom, which

leads to greater problems in manufacturing, calibration

and higher cost. Active mechanical cooling is also

likely to be necessary to cool the array (passive

radiative cooling may be possible for pushbroom

detectors). The discontinuous motion also presents

problems—the system has to settle between each step.

A last option, which is not appropriate for Landsat, is

a full stare system. Satellite velocities in low-Earth

orbit are too fast to allow a full stare system to dwell

long enough on a region of interest. Full stare systems

could be used in geosynchronous orbits.

As noted at the beginning of this appendix, the risks

in developing a new sensor system have two components: the technical maturity of component technologies and the design maturity. A particular design that

has not been used before may be a relatively risky

venture for an operational program, even if it is based

on proven technology. Some concepts for advanced

Landsats would stress both component maturity and

design maturity.

A notable example of a new component technology

that might enable the design of smaller, lighter, and

less expensive land remote sensing instruments, with

much greater spectral capabilities, is the linear spectral
144 I Remote Sensing From Space

wedge filter, the heart of a proposed “Wedge Spectrometer. ’76 The wedge spectrometer, under development at Hughes Santa Barbara Research Center

(SBRC), would be an extremely compact visible and

infrared imaging spectrometer. A demonstration system has been fabricated; it uses a 1 cm2 linear spectral

wedge filter and detector array to gather a 128 X 128

pixel image in each of about 64 spectral bands in the

visible/near-infrared region (0.4-0.85 microns) .77 SBRC

has tested this system on an aircraft under ARPA

sponsorship and generated image products.

The compactness of the wedge spectrometer is

achieved in part because spectral discrimination occurs

in a focused beam. In contrast, imaging spectrometers

that use gratings or prisms to disperse light require

collimating and reimaging optical and mechanical

components. The wedge spectrometer is also thought

to be inherently cheaper and more rugged than grating

or prism instruments. The key element of the system,

the filter wedge, has been fabricated and is in use in

devices such as laser warning receivers. However, the

filter wedge in a laser warning receiver would not be

suitable for calibrated remote sensing.

Officials at SBRC informed OTA of several spectral

and radiometric performance issues that require further

work so that a wedge spectrometer might be used in

Earth remote sensing applications that require a high

degree of radiometric and spectral sensitivity.78 SBRC

is currently under contract to the Defense Nuclear

Agency to demonstrate the wedge spectrometer for

treaty verification applications. SBRC expects to

demonstrate the device operation in the short-wave

infrared (SWIR) bands in calendar year 1993.79

76 me key elaent of the w~ge Spectrometer is the linear spectral wedge filter; a thin-fb optical device that &ansmits hght at a center

wavelength that is specified by the spatial position of illumination on the fiher. (A thin film of oil selects light via a similar ‘‘interference’

effect and accounts for the familiar rainbow of colors that are seen from varying thicknesses of an oil slick. The wedge falter is, in effecc an

interference filter with a thickness that varies linearly along one axis.) Therefore, if an array of detectors is placed behind the filter, each detector

will encounter light from a scene at a different center wavelength. If there is a linear variation in wavelength versus spatiat positiom the array

output is effectively the sampled spectrum of the scene. An array of detectors behind the falter will vary spatially in one direction and spectrally

in a perpendicular direction. Scanning the falter/array assembly along the spectrat dimension will build a 2-dimensional spatial image in each

of the spectrat bands transmitted by the filter.

rI ~e new.~wed is often defined as 0.4- 1.0 micro~.

78 A ~ljor issue for the filter wedge 1S improving “out of band’ performance---currently, energy at wavelen@hs other than at the center

wavelength specified by the spatial position of illumination on the filter may be passed. This energy undergoes multiple reflections within the

filter substrate and results in inaccuracies in spectral information. Grating or prism systems are immune from this problem.

79 me SWIR is often defined as 1.0-2.5 microns.
Appendix C:

Military Uses

of Civilian

Remote Sensing

Data

T

his appendix addresses the military utility of data from civilian

remote-sensing satellites. This utility draws the interest Of

those who might ignore the satellites and their more prosaic

utility for Earth-sciences applications. Technically, it presses

the satellites to their limits of resolution, both spatial and spectral, and

timeliness. Politically, it raises questions of who should be allowed to

buy what data. Militarily, it brings a whole new group of intelligence

platforms, for what they are worth, into play for only their marginal

cost. The Department of Defense has been purchasing remotely sensed

data from EOSAT (Landsat) and SPOT Image (SPOT) for some time. 1

However, tile extensive use of Landsat and SPOT data in the Persian

Gulf Conflict has awakened public and congressional interest in the

subject and focused attention on the issues involved.

This appendix does not address such questions as the civilian

(scientific) utility of military satellites, or the “overlap” of civilian and

military satellite capabilities. Thus, the sensitive question of the

capabilities of military satellites does not concern us here-we need

only investigate the capabilities of civilian satellites, and the question

of how well those capabilities might serve military needs.

| Military Remote Sensing Missions

Military remote sensing missions include reconnaissance (including

broad area search, combat intelligence, indications and warning of war,

and arms control verification); mapping, charting, and geodesy; and

meteorology. While rule-of-thumb precepts quantifying the capabilities needed to perform certain tasks abound, we find them wanting and

1 U.S. Congress, Office of Technology Assessment, l?emote Sensing and the Private

Sector; l.rsue.~ for D/.rcu.r.rion, OTA-TM-lSC-20 (Washing[on, DC U.S. Government

Printing Office, March 1984).

2 Or capabihty—most such precepts reduce satellite capabilities to a single parameter,

‘‘resolution.

145
146 I Remote Sensing From Space

prefer instead to be guided by instances in which

specific satellites imaged specific targets of military

interest, or targets like those of military interest. Seen

in this light, even some of the least promising civilian

satellites show surprising potential military utility.

RECONNAISSANCE MISSIONS

Reconnaissance is ‘‘a mission undertaken to obtain,

by visual observation or other detection methods,

information about the activities and resources of an

enemy or potential enemy. ‘‘3 This mission dates back

at least as far as the spies Moses and Joshua sent into

the Promised Land,4 and has traditionally been the

province of unarmed or Lightly armed scouts (like

Joshua and his men), as well as cavalry, balloons,5 and

aircraft. Particular reconnaissance missions include

(roughly in ascending order of difficulty) broad area

search; indications and warning; combat intelligence;

and arms control agreement verification.

Broad Area Search—This mission is the most

unfocused reconnaissance possible: sweeping attention

to an area of land or sea looking for previously

undetected items of potential military significance,

rather than for some particular military installation or

formation. The enormous scope of the typical broad

area search mission is, typically, somewhat offset by

the large size of the targets of interest: when searching

the hinterlands, one probably seeks clandestine or new

military installations, indications of new military

programs, and the like. Detailed examination of what

one finds can be done later, with more focused

coverage.

Broad area search is almost the norm for reconnaissance at sea: even in peacetime, ships and airplanes

patrol the oceans to see whatever is there. While their

efforts are largely focused on submarines, these

difficult and yet important targets do not get all of the

attention; tracking of surface ships remains a vital

mission in the United States Navy.

Indications and Warning—Indications and Warning comprises:

.,. those intelligence activities intended to detect and

report time-sensitive intelligence information on foreign developments that could pose a threat to the United

States or allied military, political, or economic interests

or to U.S. citizens abroad. It includes forewarning of

enemy actions or intentions; the imminence of hostilities; insurgent or other attack on the United States, its

overseas forces, or allied nations; hostile reactions to

United States reconnaissance activities, terrorists’ attacks; and other similar events.b

During crisis, rearrangement of aircraft, tanks,

railcars, or ships within their basing areas, or their

departure from their basing areas, could lead one to

expect that an attack, or at the very least an alert, was

underway. Vigilance regarding warning signs is a

major intelligence mission for the United States. By its

very nature, this mission must be performed continuously. Its intensity increases during periods of tension

and crisis.

Combat Intelligence-Combat intelligence is ‘that

knowledge of the enemy, weather, and geographical

features required by a commarider in the planning and

conduct of military operations, It provides military

forces with enormous leverage, and is a prerequisite for

the American style of War,g and, indeed, for victory

itself, ‘‘Knowledge of the enemy” includes the size

and character of his forces, where they are and where

they are not, the routes by which they are supplied, the

extent of their logistic preparation for movement or

combat, the nature of any fortifications they may

occupy, and so on. It also includes the character of

terrain and weather where operations might occur.

3 Depa~~nt of Defense Dictiona~ of Military and Associated Term.r (Joint Pub 1-02, formerly JCS ~b 1). ~s is tie fist def~tion of

.

“reconnaissance.’ The second is more general and includes mapping, hydrography, etc..

4 Numbers 13: 1-25 and Joshti 2:1-24. (See also Numbers 13:27 and 13:28 for an early example of an ‘‘On the one hand ... , but on the

other hand . . . “ intelligence assessment.)

s Both crewed and otherwise. See Curtis Peebles, The Moby Dick Projecf (WashingtorL DC: Smithsonian Institution+ 1991).

b Department of Defense Dictionary of MiIita~ and Associated Terms, op. cit., footnote 3, p. 177.

7 Ibid., p. 74.

g * ‘No commander an succ~d ~ess he demands and receives the intelligence and combat kfOImiNiOn he netXk. ’ Udd S@teS Army

FM 100-5, Operations, August 1982, Washir@o~ DC, p. 6-6.
Appendix C-Military Uses of Civilian Remote Sensing Data I 147

Surprisingly, military weather is not quite the same

as civilian weather. Civilian satellites presently make

significant contributions to the military’s weather

forecasting: the military person’s “theater’ and the

meteorologist ‘‘mesoscale’ correspond to about the

same spatial dimensions-on the order of a million

square kilometers. But the knowledge of weather

required for the combat intelligence mission can

include scales of time and space not normally associated with weather forecasts, right down to the limiting

case of informing a commander as to the current

weather at his present location. Military meteorology

also includes measurement of parameters seldom

wanted or needed in the civilian world, such as direct

measurement of rain rate.9 Civilian weather satellites’

deficiencies in satisfying military needs include:

atmospheric sensing and observation capabilities,

meteorological data acquisition and assimilation systems, and models needed to make reliable forecasts

and ‘‘nowcasts’ (descriptions of the weather within

the coming day) of mesoscale weather with resolution

of kilometers, extent of thousands of kilometers, and

timescales of 6 to 72 hours. The military’s goal of

worldwide rapid response exceeds any current capability, military or civilian, for collecting data and turning

them into a forecast. ’”

Some argue that the military’s asserted need for its

own weather satellite system, the Defense Meteorological Satellite Program (DMSP), stems from bureaucratic, not meteorological, concerns:

. . . there is considerable evidence to justify initiating

action to converge the DMSP and TIROS systems.

What has been lacking is sufficient impetus for the

federal agencies involved to take such action.11

However, DMSP proponents can point to the woes of

GOES-Next as evidence to support their position that

the military need for weather forecasting is too great to

be left in the hands of any other organization.

Monitoring Arms Control Agreements-Arms

control agreement verification is:

. . . a concept that entails the collection, processing, and

reporting of data indicating testing or employment of

proscribed weapon systems, including country of origin

and location, weapon and payload identification, and

event type. ’2

It also entails the evaluation of those data, and the

consideration of them in light of a larger political

context. Congress, particularly the Senate-in the

exercise of its Constitutional mandate to advise and

consent in the making of treaties-has made verifiability a prerequisite for most arms control treaties. While

verification entails many ingredients other than those

listed above (including political judgment-calls), the

Joint Chiefs’ list includes most or all of what

arms-control theorists refer to as the ‘‘monitoring’

part of verification; arms control agreement monitoring has become an important task for the U.S.

intelligence community. Indeed, some have argued

that this one task has preoccupied U.S. hightechnology intelligence collection as a whole.13

MISSIONS OTHER THAN RECONNAISSANCE

Mapping, Charting, and Geodesy-Tradition dictates the use of the word “map” by ground forces and

the use of the word ‘‘chart’ by naval forces, including

each force’s respective air arms. 14 Geodesy is the

measurement of the shape of the Earth. The Defense

Mapping Agency uses the phrase ‘Mapping, Charting,

and Geodesy” (MC&G) as the description of its

principal mission,

15 defining the term as fOllows:

9 Civilian meteorologists can let rainwater accumulate and then issue a report of the amount of rainfatl recorded overa cetiain time. Military

meteorologists can need to know instantaneous rain rate, because of its effect on radar systems.

10 ~s Pmgaph tiaws on “Comments on Military Uses of Civilian Remote Sensing Satellites, ” Major General Robert A. Rosenberg

USAF, (retired), Aug. 4, 1992.

I I Gener~ ~co~t~g Office, GAO NSIAD-87- 107, Weather Satellites, p. 4.

12 Department of Defense Dictiona~ of Milita~~ and Associated Terms, Op. cit., footnote 3, p. 36.

13 ~gelo Codevilla, znforming Sratecraji (New York+ W: Free ~ess, 1992)* P. 112.

ILt me jo~t Semlces* Dep~rtmenf of Defense DJctionaV of Mi/ita~ and Associated Terms (Joint Pub 1-02, formerly JCS ~b 1) defines a

‘ ‘map’ as ‘‘a graphic representation, usually on a plane surface, and at an established scale, of natural or artificial features on the surface of

a part or the whole of the earth . . . ,’ p. 219.

15 Defense Mapping Agency briefing to OTA s~f, May 13, 1992.
148 I Remote Sensing From Space

MC&G is the combination of those sciences,

processes and data which form the basis for preparing

maps, charts and related products and for determining

the size and shape of the Earth and its gravity and

magnetic fields.

MC&G includes the collection, evaluation, transformation, generation, storage and dissemination of topographic, hydrographic, cultural, navigational, geographic names, geodetic, gravimetric and geomagnetic

data. The data are manipulated to support air, land and

sea navigation, weapon orientation, target positioning,

military operations, planning and training.

Meteorology—Meteorological data are “meteorological facts pertaining to the atmosphere, such as

wind, temperature, air density, and other phenomena

which affect military operations. 16 The military

voraciously consumes weather data. These data are

routinely needed for mission planning and assessment

of possible enemy operations, and occasionally needed

for such other tasks as predicting the coverage of

chemical weapons and smoke from frees.

| Civilian Satellites and the Requirements

of Military Remote Sensing Missions

To begin an evaluation of civilian satellites’ military

utility, we need to compare their characteristics to the

requirements of the military’s remote sensing missions, The previous section has treated the latter; we

now turn to the former.

CIVILIAN SATELLITE CHARACTERISTICS

The most-discussed characteristic of remote sensing

satellites is their imagers’ ‘‘ground resolution, ’ or

ability to distinguish objects on the surface of the

Earth. (See box 4-B.) Sensor characteristics other than

resolution are often overlooked. These include scene

size, the spectral range within which the sensor

operates, the availability of stereo imagery, whether

the pictures are digitized or not, the “metric” or

accuracy with which the sensor knows and reports its

own location, the timeliness with which the images are

returned, the frequency with which a given target can

be revisited, the fraction of the time that the system can

devote to taking pictures,17 the entire system’s throughput capacity, and the cost of the imagery. This section

Table C-l—” Resolution” (ground sample distance)

of Selected Civilian Satellites

Resolution

Satellite Sensor (in meters)

addresses a variety of civilian satellite capabilities,

albeit with resolution as the first among equals (table

c-l).

The basic image parameters-spatial resolution,

scene size, spectral resolution, and spectral coveragecompete for satellite resources. Fixed or expensive-tochange constraints such as the data capacity of the

downlink, the ‘ ‘speed’ of the sensor optics, and

ultimately the weight of the satellite itself, place upper

16 Department of Defe~e Dictionary of Military and Associated Terms, op. cit., foo~ote 3* P. 227.

17 AS opposed t. pe-fom~g ~~er activities, such as send~g do~ to an E* s~tion the pieties that have tieady been tilkc?!ll.
Appendix C-Military Uses of Civilian Remote Sensing Data I 149

limits on the amount of information the image can

contain. Within those limits, tradeoffs must be made so

as to maximize the image’s utility for its intended

purpose. A multipurpose satellite entails another level

of tradeoff, compromise among purposes. A civilian

satellite, especially a commercial one, is intended to be

all things to all customers, and thus will not necessarily

fill any one customer’s bill perfectly.

Resolution----One often sees the optical acuity of

remote sensing systems expressed in terms of the

ground resolution (or ‘ ‘resolution,” or “ground sample distance”) of their imagery-the closest that two

objects can be and still be perceived as two separate

objects. 18 In practice, it is usually about twice the size

of the smallest item that can be perceived as a separate

object.

Many sources in the open intelligence literature

tabulate the utility of different ground resolutions

(table C-2).19 These sources generally list various

objects and the ground resolutions needed to perform

various tasks with respect to these objects, such as

‘‘detection, ‘‘recognition, ’ ‘‘identification, and

‘‘technical analysis. ’ For example, 9-meter resolution

allows the detection of a ship, but 3- to 4-meter

resolution may be needed to determine the type of the

ship (e.g., ‘‘submarine’ and even finer resolution is

needed to determine its class (e.g., Oscar). The many

sources, some quoting from others, show rough

agreement as to the resolutions needed for the different

tasks.

A more sophisticated expression of sensor definition, the Image Interpretability Rating Scale (IIRS),

Table C-2—Resolution Requirements (in meters)

Sorted by Task and Target

Task

Target Detect Identify Analyze

Surface ships . . . . . . . 15 0.15 0.04

Land minefield. . . . . . 3 0.30 0.08

Missile sites . . . . . . . . . 3 0.15 0.04

takes into account aspects of image quality other than

ground resolution. These include contrast, intensity,

shadowing, and so on. The IIRS is, at base, a subjective

rating system: it works from the image’s utility in

detecting, identifying, or analyzing given types of

target to the image’s rating on the scale.20

Both IIRS and the more objective (but simplistic)

ground resolution paradigm address the utility of

images. However, the tasks to which they refer are of

the most rudimentary nature. Military consumers of

remotely sensed data are really not interested in

detecting, identifying, or analyzing particular objects.

They care about such tasks as mapping, forecasting,

targeting, and verifying. The ground resolution needed

to perform these tasks is not so clear-cut, and

deficiencies in image quality can in some cases be

made good by virtuoso performance of the image

interpreter’s art. For example, ships too small to be

seen at a given resolution could, if under way, be

detected via their wakes. Fences, themselves an

IS The Depurtmenf ~fDefen~e Dic(iona~ of Military and Associated Terms (Joint Pub 1-02, formerly JCS ~b 1 ) defines ‘‘resolution’ M

‘‘a measurement of the smallest detail wh]ch can be distinguished by a sensor system under specific conditions. ” The role of the word

‘ ‘distinguished” in this definition is sometimes given insufficient emphasis.

‘9 These include:

McDonnell Douglas Aircraft Corp., The Reconnaissance Handy Book, p. 125.

Ronald J. Ondrejk~ ‘‘Imaging Technologies, in Arms Conrrol l’enfication, Kosta Tsipis, David W. Hafemeister, and Penny Janeway

(cds.), p, 67.

Jeffery T. Richelson, ‘ ‘Implications for Nations Without Space-Based Intelligence-Collection Capabilities, ’ (in Civilian Obsen!ation

Sufellites and Infernanonul Security, Peter Zimmerman et at. (eds.)), p. 60.

Ronald A. Scribncr et al,, The Verification Challenge: Problems and Promise of Strategic Nuclear Arms Control Verification, p. 32.

U. S, Congress, Office of Technology Assessment, Verification Technologies: Cooperative Aerial Surveillance in International

Agreements, OTA-ISC-40, (Washington, DC: U.S. Government Printing Office, July 1991), p. 38.

United States Department of Defense, Headquarters, Department of the Army, STP 34-% D1-SM Soldier’s Manua/ Skill Level 1 MOS

96D Imagery Analyst, pp. 2-146 to 2-150.

~ Itek CII Systems Bullctm IL-Z, ‘‘IIRS Image Interpretability Rating Scale” (Lexingtom MA: Litton Itek Optical Systems, 1984).
150 I Remote Sensing From Space

indicator of the nature of the facility they surround,21- 22

can be detected by the way they channel foot traffic

(and the paths it creates),23 and by its effect on

vegetation, 24 while dummy installations are given

away by the absence of foot traffic in their vicinities25

or the lack of snowmelt on their roofs.26 In a most

remarkable instance of detecting the non-resolvable, J.

Skorve found a set of seven Soviet submarinecommunications antennas in an 80-meter Landsat

picture. 27 Although the antennas themselves cannot be

seen, the snowflake pattern28 created by their bases,

their stays, and their stays’ bases is some 1,700 meters

across. Skorve apparently deduced the function of the

antennas from their large size, which bespeaks a long

wavelength most suitable for communication with

submarin es. He indicates that weather conditions

prevented a cued follow-up shot with the higherresolution SPOT. Working with even less raw material, Peter Zimmerman analyzed a SPOT picture of

the Soviet Northern Fleet headquarters at Severomorsk, concluding that:

. . . there are no buildings or rocky terrain around the

base, which suggests that caverns have been blasted out

of the cliffside.29

Photo interpreters are, however, only human, and

their logic can at times be faulty. For example, analysts

noted that a certain building in Iraq lacked the multiple

surrounding fences associated with high-technology

military work. However, it was later discovered that

the building lay inside a huge military facility, whose

security fences apparently lay entirely outside the

boundaries of the overhead picture.30

Moreover, targets of sufficient contrast can be

detected even if they are too small to be resolved. (We

are familiar with this effect because of the operation of

our own eyes, which can detect distant stars without

resolving them.) Again citing the example of a ship,

heat from machinery or absorbed sunlight could make

the ship such a bright thermal infrared source, or

reflected sunlight could make it such a bright visible,

near infrared, or medium infrared source—in contrast

to the surrounding sea—that it would light Up a whole

pixel31 despite occupying far less space than is imaged

by that pixel. Alternatively, concave corners in the

ship’s superstructure could strongly reflect energy

straight back to a radar satellite (such as the nowdefunct AlmaZ-l, or ERS-1), again lighting up a point

on the image and showing that something other than

the ocean was there, even though it could not be

resolved.

The whole resolution concept is also confounded by

targets that exceed the system’s resolution in one

dimension while falling short in another. A railroad,

for example, is narrower than 30 meters but far

longer—railroads can and do occasionally appear in

21 soldier’s Manul Sb”ii Level I, Imagery Analyst, p. 2-439.

22 1‘me Space Media Network a~ysts who published a story about the Soviet electro-optical facility atop Mt. S~glok in Tadjikistan felt

confident that they had seen double fencing on that site. Such indications of security call attention to an industrial site that might otherwise

have been overlooked. (Peter Zimmerman, ‘‘The Use of ‘Open Market Observation Satellites for the Monitoring of Multilateral Arms Control

Accords,” p. 51.)

23 Soldier’s Ma~l Sia”ll Level i, op. cit., foomote 21, p. 2-367.

B Ibid., p. 2457.

~ Ibid., p. 2-360.

26 Dino A. Brugioni, ‘‘The Serendipity Effect of Aerial Reconnaissance, Interdisciplinary Science Reviews, vol. 14, No. 1, 1989, p. 16.

Brugioni also points out that snowplowing habits can indicate facilities’ functions: headquarters buildings typically receive the most prompt

service.

27 Joby Skome, The Ko/a Zrnage Atlas, Oslo, The Norwegian Atlantic committee, 1991.

~ ~e sixfold symme~ arises because six antennas surround the seventh in a hexagon.

29 peter z~emm ‘‘A New Resource fOr Arms control, “ New Scienh”st, Sept. 23, 1989, p. 39.

30 Jay c, Davis and David A. KaY~ ‘ ‘Iraq’s Secret Nuclear Weapons Program, ” Physics Today, July 1992, p. 24.

31 A ‘‘p~el, ’ ‘ short for ‘‘picture element, ‘‘ is a single one of the many dots, of differing color and/or brightness, that combine to form a

picture. Computer graphics use true pixels, while newspaper and magazine pictures use an offset image printing process whose dots can be

seen with a magnifying glass, Broadcast TV forms images that are discrete, like computer images, in the scan-to-scan dimension and diffuse,

like emulsion film images, in the along-the-scan one.
— . ——

Appendix C-Military Uses of Civilian Remote Sensing Data I 151

Landsat images, because a pattern made up of nonresolvable elements can be discerned.32

Thus, resolution requirements are hard to specify.

The following sections assess the military utility of

particular satellites not just in terms of the resolutions

needed for particular tasks, but in terms of the

satellites’ proven overall abilities to see targets of

interest in MC&G, meteorology, broad area search,

Indications and Warning, battlefield intelligence, and

arms control monitoring. Considerable overlap exists

in these target categories. For example, a large

clandestine missile factory or radar would be a broad

area search target and also an arms-control monitoring

target.

Scene Size-Just as users will always hanker after

finer resolution, they will always want larger scene

sizes, everything else being equal. However, larger

scenes come at a price-in dollars, resolution, or

both-and therefore are subject to some limits.

Spectrum—"Panchromatic" sensors make images

that a lay person would term a black-and-white

photograph, using visible light.

“Spectral coverage’ refers to the satellite’s ability

to detect light, and thus form images, in different parts

of the spectrum, such as the visible band or infrared.

These can all be combined into a “panchromatic”

(black-and-white) picture, or separated. “Multispectral” sensors take, or construct, what the lay person

would call color pictures. Normally the colors seen in

the color pictures are not the colors of the orginal

scene, but are instead a ‘‘fauvist’ color set chosen so

as to make the information contained in the picture as

apparent as possible to the human eye. One obvious

reason for making such a color substitution is that the

wavelengths orginally collected by the sensor may not

be visible to the human eye. For example, the infrared

portion of the spectrum (with wavelengths too long to

be seen by the human eye) contains data useful in a

variety of circumstances such as nighttime. Therefore

a ‘‘color composite’ image is used, in which the

various parts of the spectrum sampled by the sensor are

represented by colors visible to the human eye. In the

common case of a combination using the near infrared

band, such as a Landsat 4,3,2 TM band combination,

the term “false color” is often used to describe this

form of enhanced presentation.

‘‘Spectral resolution’ refers to the satellite’s ability

to subdivide the covered portion of the spectrum into

smaller segments, in effect discerning different colors

in the scene. while multispectral sensors of the Landsat

class collect images using a handful of wavelength

bands, recent advances in detector technology and

computational power have made it possible to build

sensors that have hundreds of very narrow spectral

bands. These “hyperspectral” imaging systems, still

experimental in nature, have the potential to discern

much additional information in the scene, contributing

to the detection of camouflaged or concealed targets,

ocean bottom features, small-plot crop plantings of

interest to drug interdiction efforts, detailed structures

in clouds, and other highly detailed image features of

military interest. Whereas panchromatic sensors combine all the light they receive into a single image and

multispectral sensors sample light in several nonadjacent color bands, hyperspectal sensors sort incoming light into a hundred or more mutually exclusive

and collectively exhaustive ‘‘bins. The detailed

spectral information thus captured allows for detailed

examination of the scene, especially with regard to

identifying particular materials in the scene by their

unique spectral “fingerprints.”33

Synthetic Aperture Radars, such as those aboard the

now-defunct Almaz-1, JERS - 1, and ERS - 1, operate at

even longer wavelengths, the microwave portion of the

electromagnetic spectrum. Their final products have

the appearance of black-and-white photographs, but

they can be colorized, for example to display soil

characteristics of particular interest.

Stereoscope—Three-dimensional or “stereo” images are useful in a wide variety of tasks, and essential

in map-making and the creation of scenery in flight

simulators. A stereo satellite image combines images

taken at slightly different locations in the fashion

familiar from childhood’s various ‘‘3-D Viewer’ toys

32 ~even more complicated CKSe is that of minefield. The minefield’s extent can exceed the sensor’s resolution in bo~ dfi~tiom, ~~

each mine being nonresolvably smaI1. In some cases, the trained eye can perceive the presence of the field, based on the pattern of nonresolved

specks.

33 Ro5enberg, op. cit., foo~ote 10, and an Aug. 27, 1992, briefing at the Naval Rti~ch LaboratoV, was~ngton, DC on ~ek ~D1cE

(Wpq=@~ W@J Im3ng and co~e~tion Expe~ent) prok=t.
152 I Remote Sensing From Space

and, indeed, from human depth perception itself. In

some applications, a photo interpreter sees and benefits

from this illusion personally;34 in others, computers

manipulate the data to produce a contour map, with no

actual 3-D viewing having taken place. The value of

stereoscopic coverage is so great as to elicit a rare

instance of sardonic wit from the U.S. Army in its

Soldier’s Manual, Skill Level I Irnagery Analyst: “YOU

will appreciate the advantages of stereoscope more

each time you interpret photography that doesn’t have

sufficient overlap to permit stereo viewing. ’35 For best

results with human viewing, the separation between

the points where the picture was snapped should be

about a tenth of the distance to the target.36

Photo reconnaissance aircraft produce the stereo

pairs by taking photographs in rapid succession during

their pass over the target. Civilian satellites currently

lack this ability, and can make stereo pairs only by

carefully planned shots on separate orbits. JERS-1

planning included the ability to make along-track

stereo pairs .37

Metric—Accurate photogrammetric measurement

of the objects seen in the image requires an accurate

account of the distance and viewing angle from the

sensor to the target. If, in addition, accurate absolute

location of the objects with respect to a larger

coordinate system (such as global latitude, longititude,

and altitude) is desired, an accurate account of the

absolute location of the sensor is needed. Such location

is now best obtained from the Global Positioning

System (GPS), whose unencrypted signals normally

allow three-dimensional location to within 80 meters

or better and time-domain location within a hundredmillionth of a second and whose encrypted signals

provide even freer location and time accuracy. The

analogous Russian GLONASS system provides comparable accuracy but poor coverage. Through repeated

measurements, the accuracy of either system can be

increased. Access to the ‘‘precise-code’ GPS output,

which is normally encrypted, could allow a satellite to

locate itself to within lo-meter accuracy or better.

Special processing software can also improve metric

accuracy. For example, routine decisionmaking data

processing can locate SPOT data to within half a

pixel. 38

Considerable accuracy is possible even without

such systems. France’s SPOT, for example, can locate

its pictures to within one kilometer purely through the

use of its own orbit data.39

Timeliness-There are actually two aspects of

timeliness, both desirable. First, the rapidity with

which an order is filled, measured in terms of the

length of time between the request and the collection

of the imagery. Second, the freshness of the imagery,

measured in terms of the length of time between the

moment that the image is collected and the moment it

is delivered to the customer. These two types of

timeliness are not strongly related, except insofar as

most customers will want them both.

The former depends in part on the ‘‘revisit time’ of

the satellite (how long it takes between successive

passes over the same spot) and the degree to which it

can aim its camera obliquely, obviating the need for an

exact pass over the target. These combine to create an

average delay between successive opportunities to

image the target. The actual delay—which one might

term the “visit time’ ’-experienced by the customer

will vary according to how lucky he or she is: a lucky

customer will request a picture right before an opportunity to schedule it arises, while an unlucky one will

request a picture just after a good time to take it has

passed, resulting in a delay. Such a customer might

want to shop around for a different satellite’s services.

Customers seeking visible-light views of regions

frequently covered by clouds will also find themselves

subject to collection delays caused by weather. Revisit

times can be considered two ways: the revisit time of

a particular satellite, or that afforded by a satellite

system, in which a pair of satellites can halve the revisit

time. The second column of the table below reflects

~ Wl@ ~r~ps, an ficially exaggerated depth dimension so as to aid in the interpretation task.

~S SOldier’S Man~l, skill Lel*el I, op. cit., footnote 21, p. 2-281.

36 Dodd Light u.s.G.s National Aerial PhotoWaphy ~o~

37 zimme~~ op. cit., footnote 22, p. 21.

38 wil~ Ke~edy, Hughes SIX Corp., personal communication, July 8, 1992.

w Wflfim ~ith ad David W. Simpso% ‘ ‘Monitoring Underground NUCIW Tests, ‘‘ in Peter Zimrnermaq Civilian Observation Satellites

and International Security (New York NY: St. Martin’s, 1990), p. 116.
Appendix C-Military Uses of Civilian Remote Sensing Data I 153

Table C-3—Timeliness of Selected Civilian

Sensing Systems

Revisit time “Freshness”

Satellite (days) (days)

this distinction. Also counted as part of the “visit

time ’ is the delay entailed in processing the customer’s order on the ground. This delay-often best

measured in weeks in business-as-usual commercial

operation—is far beyond acceptable limits for many

military uses.

The second type of timeliness, which one might

term ‘ ‘freshness, ” depends upon the way pictures get

from the satellite to the customer. Normally, processing on the ground-needed to turn a signal from the

spacecraft into a usable image—accounts for much of

this delay. In the case of Resurs-F, however, additional

delay results from the use of a film-return-as opposed

to TV-like-transmission of the picture from the

satellite, Film-return systems return a capsule of

photographic film to the ground for processing. A

lucky customer will request a picture just before the

roll of film is used up. This aspect of timeliness is a

major difference between the two high-resolution

competitors, SPOT (table C-3) and Resurs-F: SPOT

uses a digital video downlink while Resurs-F uses a

physical film-return system (see app, D).

Throughput—Image vendors can only sell pictures

as fast as they can take them. At some level of demand,

perhaps reachable by even a single customer during

period of peak use such as a war, further pictures

cannot be purchased at all for a while, and additional

requests will have to go unfilled.

Cost—However important the mission, cost is an

important consideration. Civilian satellites are no

exception. Whether a cost is deemed ‘high’ or ‘low’

depends upon how it compares to the costs of

alternative means of accomplishing the mission and to

the cost of allowing the mission to remain unperformed (table C-4).

Control--space-race handicappers will already have

noted that the civilian satellites with the freest resolutions (SPOT, Resurs-F, and the now-defunct Alrnaz)

do not belong to the United States. Therefore, political

considerations might vitiate the potential military

utility of these satellites in a crisis, In the case of the

Gulf War, this effect worked in favor of the United

States: the French were on our side, and sold SPOT

images only to ‘‘well known clients in support of the

allied effort. ’40 On the other hand, it has been stated

that France denied the United States use of SPOT

during planning for the 1986 raid on Libya. Even

during normal peacetime operation Russia has had a

policy of not selling Resurs-F imagery of its own

territory, though Almaz images are available. This

practice, too, could change in light of Russian needs

for foreign exchange.

40 st~p~ne Chenard, ‘ ‘Lessons of the First Space War, ” Space Markets, April 1991, p. 5.
154 I Remote Sensing From Space

Table C-4-Costs and Capacities of

Selected Civilian Satellites

$1,000

CIVILIAN SATELLITES’ USE IN MILITARY

saw considerable use in the Persian Gulf War.

One particular application of mapping is the study

of deployment-constraining terrain characteristics in

the deployment regions of the Russian land-mobile

SS-25 missile. Budget Director Richard Darman cited

the Defense Department ‘‘absolute need’ for multispectral images as a reason to turn the Landsat program

over to DoD,41 perhaps to perform this area limitation

analysis.

Mapping does not necessarily mean undetailed

coverage; some important targets for mapping, such as

railroads, are not always visible at the resolutions often

associated with maps. Because of its chancy success in

picking up these targets, Landsat is the subject of

varying performance assessments, ranging from ‘Landsat does not show the railroads, sometimes not even the

rivers’ ’42 to:

. . . since MSI maps are images of the Earth, they

show existing roads, trails, airfields, etc. Clear,

open areas, which may be suitable for military

purposes, also stand out and are easily factored

into planning. For example, after the 82nd

Airborne Division obtained a Landsat map of

Kuwait City, it asked for national imagery to

determine if there were traps or obstructions that

would prevent an airborne landing. MSI images

may be able to show surface or subsurface

features down to 30 meters, depending on water

clarity. The Navy used MSI data in planning

amphibious operations during Operations Desert

Shield and Desert Storm.43

Certainly some railroads, roads, and rivers are

visible in the Landsat pictures (images 1-17) of the

Kola peninsula used in J. Skorve’s The Kola Satellite

Image Atlas (footnote 27).

Both SPOT and Landsat data are used in military

flight simulators. An important and emerging part of

MC&G relates to combat intelligence: the creation of

databases for guidance systems. While the creation of

scenes used by DSMAC,44 for example, could well be

categorized as combat intelligence, the maps used by

the pilot or TERCOM45 during the approach properly

belong to the realm of MC&G. Though Landsat data

were not used in preparing TERCOM maps for the

41 ~~ ~womt &am from ‘ ‘SAC n~ds ~dsat to hut mobile missiles, ’ ‘ Military Space, Dec. 18, 1989 (Arlington, VA: Pasha

Publications), p. 3.

42 Brigadier &ner~ Da,le E, Stovall, USAF, quoted in ‘‘Lessons of the First Space War, ’ Space kfarkers, Ap~ 1991, p. 6.

43 Sareq of ~fense Dick Cheney, IJ. S. Department of Defense, Conduct o~the Persian Guy War: Find Report tO Congre$$, p. T-23 1.

This reference, while in a section entitled ‘Muki-Spectral Imagery: LandSat,’ might refer to SPOT MSI as well or instead. SPOT is mentioned

in an earlier subsection but without acknowledgment that SPOT images were used in the Persian Gulf War, which they were.

M D1gi~ Scene ~tc~g and correlation, ‘l%is system accomplishes terminal guidance by relating a TV image of tie sighted met ma

to a stored image, and guiding the missile to that part of the image that has been designated as the target.

45 Temain cone~tion ~d ~tc~, ~ssyst~ uses stored ~ps of ce~ patches to be ovefiown en route to the target. when tie

missile’s inertial guidance system decides that it is over a patck it activates an altimeter. The alimeter readings are then correlated with the

elevations present in the patch to fiid the missile’s ground track. A course correctioncsn then be made, if necessary. Unlike DSMAC, TERCOM

looks only at elevations on a one-dimensional ground track, not a two-dimensional landscape.
Appendix C-Military Uses of Civilian Remote Sensing Data I 155

Tomahawk cruise missile strikes executed in Operation Desert Storm, the ability to make such use of

Landsat data is expected in the near future.46

Uniquely, the MC&G mission demands extreme

consistency in its data. Change analysis is useful in

almost all military uses of remotely sensed data, but the

changes exploited in MC&G imagery maybe so subtle

that almost any alterations in the sensor are detrimental, perhaps even fatal, to completion of the mission .47

Thus, consumers of MC&G data often oppose “upgrades” in the sensors they use, preferring old

ones—flaws and all-to new ones whose output will

not be strictly comparable to the archived outputs of

the old sensors. At the level of precision demanded by

MC&G, software cannot compensate for the effects of

concern. For example, some MC&G consumers oppose even integer-denominated improvements in resolution, even though one would think that, say, 30-

meter resolution could be recovered from 15-meter

data simply by averaging blocks of four 15-meter

pixels into single 30-meter pixels. Because of possible

nonlinearity in the response of the sensors to brightness, however, this approach can fail.

Meteorology—DoD operates meteorological satellite systems, completely devoted to serving the

weather-forecasting needs of the military.

Two Defense Meteorological Support Program

(DMSP) Block 5D-2 satellites, aided by the National

Oceanic and Atmospheric Administration (NOAA)

Polar-Orbiting Operational Environmental Satellites

(POES) as well as the European Meteosat and Soviet

Meteor civilian weather satellites, served the military’s

weather forecasting needs in the Gulf War.48

Weather and other forces change underwater currents in ways that the Navy must monitor in order to

predict sonar propagation paths, This requirement is

currently filled by civilian NOAA satellites.49

Broad Area Search-Broad area search for major

installations could be accomplished by civilian satellites. Many sources, such as certain editions of the

Department of Defense publication Soviet Military

Power and even a novel by the author Tom Clancy,

show photographs of such installations, taken by

civilian satellites. (Which is not to say that that is how

the Department of Defense or other civilian customers

orginally became aware of them.) In the cases of the

airfields, shipyards, and naval bases, even the untrained eye can readily identify the nature and function

of the facilities.

Interestingly, the coarse resolution of civilian sensors (especially those best suited to broad area search)

is less of an impediment, in the case of some

high-contrast targets, than one might imagine: detection of any target in a supposedly desolate area, even

one of sub-pixel size, is a success for the broad area

searcher (table C-5). For example, Landsat-4, using its

Band 7, detected the “Wrangel Island Anomaly,” a

circle 2 miles in diameter on the arctic ice near

Wrangel Island. This circle called attention to dots near

its center that might otherwise have been overlooked.

These turned out to result from tests of a new Soviet

submarine’s ability to punch its way through the ice,

preparatory to launching a ballistic missile. The circle

was made by an observation aircraft circling the test

site. 50 In other examples, buildings of the North

Korean nuclear plant at Yongbyon show up (albeit as

dots) in a Landsat Thematic Mapper5l picture, and

ships off California are visible in the Seasat-A radar

image. The use of the Thematic Mapper in this role is

intriguing, because it suggests the possibility of

deliberately sacrificing resolution so as to obtain

improved contrast against a target that is much hotter

than the surrounding landscape. In the same vein, one

could operate visible-light satellites at night, when

fi D. Bfian Gordo~ Chairma~ Tactical and Military Multispectral Requirements Working Group, Defense htelhgen~ Agency, testionY

of hearings before the House Committee on Science, Space and Technology and the Permanent Select Committee on Intelligence, 102d

Congress, 1st Ses., June 26, 1991. Scientific, Military, and Civilian Applications of the Landsat Progrm p. 31. Note that the essence of a

TERCOM map is its elevation data, available only from stereo imagery.

47 Ckge det~tion for ~~w Pwses may not be as subtle as that used by MC&G.

@ Chewd, op. cit., footnote 40, p. 11.

49 Ibid.

50 Some soUce~ refer to ~~fi]e as a con~~] ~her~s othe~ descfibe it as an actu~ @ce on tie ice, created by the shghtr~ effect

of the contrail. The latter explanation is more plausible in that a contrail would drift away and become diffuse, whereas a melted circle in the

ice would become more pronounced the longer the airplane loitered.

51 DOD sowces ofien call this devia the ‘ ‘Thematic Imager, ’ perhaps because its output 1s an tige, not a map.
156 I Remote Sensing From Space

Table C-5-Civilian Satellite Images of Area-Search Targets

even the poorest resolution could allow sightings of ‘‘retrocueing can also occur: once the target is

large, illuminated cities and installations.52 (Under the discovered, earlier imagery can be re-examined and the

Soviet system, there were entire cities whose existence target found in it as well.55 J. Skorve recounts his

was not publicly revealed or acknowledged.53 Similar successful implementation of both of these strategies

conditions may apply today in other countries.) using only civilian systems:

Use of coarse-resolution, broad-area (and perhaps

It was by scrutinizing a Landsat-TM image from

economical) sensors for wide-area search with selec- 1985 that the large Schagui airbase in southwestern

tive follow-up by better and more narrowly focused Kola [in the Russian Federation, formerly the U. S. S. R.]

sensors illustrates the important idea of cueing: objects was discovered. The revelation of the existence of

seen with the first system receive special attention Schagui was a real surprise since there were no

from the latter.54 In many cases, what one might term indications of it in available open sources. First it

52 Skome, op. cit., foo~ote 27, shows an example of this kind of image, made by a Defense Meteorological PrOgarn =tellite (p. 48).

53 <‘~ Russia, Swret Labs Struggle to Sun’ive, ’ New York Times, Jan. 14, 1992, p. Cl.

~ For more on cueing, see OTA’S Verijicatiun Technologies, OP. Cit., foomote 19.

55 ~oftisor R.V. Jones, retmcued by some signals intelligence, found a Gemm V-2 rocket that had previously gone unnoticed in pictures

of a V-1 test site in occupied Poland. His highty instructive account appears in his book Most Secret War (Londo& Hamish Hamittom 1978),

pp. 549-551, and is excerpted in OZ4’S Venfi”cation Technologies, op. cit., footnote 19, pp. 97-98.
Appendix C-Military Uses of Civilian Remote Sensing Data I 157

looked as though the airbase was still under construction at the time of imaging in 1985. However, later it

was possible to reveal the time-sequence of the

development of the Schagui airbase. A complete listing

of the Landsat images of the area shows that there was

coverage in 1972, 1974 and 1978. Even though the

[Landsat] MSS pictures . . . are rather rough, it was

possible to show that in the summer of 1972, the airfield

was only 25-30 per cent of its present size. The rate of

progress could be determined when the 1974 picture

became available. It showed that Schagui by then had

grown to its present size. . . . Even the Landsat TM

image of 1985 was insufficiently detailed to show the

most interesting features of the base. It was therefore a

major advance when [my group] could requisition a

SPOT-P image taken during the 1988 summer season.56

Skorve similarly describes his 1985 discovery of the

Gremikha naval base in a 1985 SPOT picture, which

retrocued him to earlier Landsat pictures.57 The base

also appears in the 1978 nighttime DMSP picture

presented by Skorve.ss Retrocueing was also used by

U.S. Air Force mission planners in their Scud-hunting

efforts during the Persian Gulf Conflict. When a

launch was detected, planners would examine preexisting SPOT pictures of the launch area, looking for

likely launcher sites.59

Submerged submarines, an important target of

broad area search at sea60, could conceivably be seen

by civilian satellites equipped with Synthetic Aperture

Radar. Though the radar waves themselves can penetrate seawater only a little, their presentation of

disturbances on the surface, potentially including

submarine wakes, would allow them to detect submarines indirectly.6l Diverse alternate traces of submarines’ passage, such as changes in the water’s temperature or even its plankton population, have received

intermittent attention over the years. 62 Conceivably

some such phenomenon could someday be detected by

a civilian satellite. Surfaced submarines would be

almost as readily detectable as ships of the same size.

The principal drawback of civilian satellite sensing

systems (and, indeed of most systems!) for broad area

search is the large number of pictures needed to

complete the search. This large number, in turn,

translates into time and money.

For example, the former Soviet Union covered

about 10 million square miles. A complete search of

that territory by Landsat would require about 1,000

pictures, obtained at a cost of $1 million over many

pciture months.63 The subsequent analysis of the Pictures

would add more time and cost to the project. SPOT

pictures are less expensive per image, but cover less

area (albeit at a higher resolution). Use of SPOT

pictures would more than double the price: it takes nine

SPOT scenes to cover a single Landsat scene.

These daunting figures suggest that true broad area

search might not be done very often. More likely, a

focused search, based on prior information such as the

locations of cities, rivers, and coastlines, would be

performed. Even so, a Landsat survey of the over 4,500

airfields in the former Soviet Union would, with one

M Skone, Op. cit., footnote 27, P. 90

57 Ibid., p, 86.

s~ Ibid., p. 48.

59 Craig Covault, ‘ ‘USAF Urges Great Use of SPOT Based on Gulf War Experience, “ A]’iution Week and Space Technology, July 13, 1992,

p. 65.

m nc m~ern defe~se hterature contains numerous descriptions of the dramatic change that would come about if ‘the oceans were made

transparent. ” In most cases, the authors have broad area search, not support of combat operations, in mind-they are concerned that

ballistic-missile launching nuclear submarines (S SBNS), whose deterrent mission rests on the other side’s ignorance of their whereabouts,

would become locatable.

61 Crmg Covault, ‘ ‘Soviet Radar Satellite Shows Potential to Detect Submarines,’ Aviation Week and Space Technology, (M. 8, 1990, pp.

22-23,

62 se ~omm Stefanlck, ,~~ategic Ann”~ubman”ne wa~are ~~ NaV,a[ s~a~egy, ~~gton, MA: Gxing[on BOOkS, 1987), especidy

app. 3.

C3 While ~ndsat would ~Wu~e o~y weeks [o orbit over ~ch scene, it could take mon~ or even years to collect a Complete Set Of

clear-weather daylight pictures. Recall Skorve’s experience in imaging the Kola Peninsula.
158 I Remote Sensing From Space

picture each, cost $18 million.64 In this case, use of

SPOT would be more economical, because an airfield

would fit inside a single scene, negating SPOT’s

disadvantage of having a smaller scene size: the SPOT

version of this search would cost only $4.5 million.

Searches at sea highlight another problem as well.

Not only would an Almaz search of the 400,000-squaremile Sea of Japan (an antisubmarine warfare arena of

modest size) have required 640 25x25-km scenes at a

total pre-analysis cost of about a million dollars, but it

would have taken at least a week to complete65—too

long to be of use in many antisubmarine warfare

scenarios.

A new broad-area search mission has arisen with

increasing military involvement in countering the

narcotics trade: searching for fields of illegal drugs.

According to a United Nations report,

. . . it would be feasible to develop a global system for

locating cultivation of illicit narcotic crops by spaceborne remote sensing devices but that preliminary

activity would need to include inspection on the ground

at selected test sites to verify the accuracy of information interpreted from satellite photography.66

Presently, there is great interest in detecting coca (from

which cocaine is derived) planted in South America.

Created as a land-use sensor, Landsat would seem

ideal for this mission, However, coca turns out to be a

difficult crop to monitor. MSS and TM differentiate

between vegetation and other features by detecting key

substances such as chlorophyll, other pigments, color

in general, water content, and even leaf structure:67 It

turns out that the contrast from the minor chlorophyll

differences among coca and other local plants such as

citrus fruits is small.

Not only is coca’s multispectral signature similar to

that of other plants in the area, but the agricultural

practices of the coca growers can stymie detection:

they interplant coca with other crops, and even grow it

in patches covered by a tree canopy. Coca tends to be

produced in small plots, commonly a half a hectare to

two hectares-so small-sized plots would be too small

to dominate a pixel,68 increasing the probability that

surrounding features will overshadow evidence of

coca. Also, other interfering features (e.g., smoke,

clouds) can interfere with satellite detection. Large

marijuana fields, however, generally create an easier

Landsat target.

Indications and Warning—The indications and

warning mission (I&W) is very demanding, and policy

makers would certainly like to be able to spread it

among as many systems as possible. Table C-6 lists a

variety of targets similar to those that might be

routinely imaged in the performance of the I&W

mission.

While aircraft are visible in Banner’s SPOT pictures

of Kabul airport, they become much more apparent

when one panchromatic image of the airport is overlaid

on another, with false color added to highlight

differences. Then the moved aircraft-which appear

only in one image or the other and are hence brightly

colored-become quite obvious not only through their

color and shape but through their placement on ramps

and runways where any large movable object would be

presumed to be an aircraft.

Banner’s SPOT-aided discovery that trucks had left

a military encampment near Kabul deserves special

note for two reasons. First, Banner’s knowledge that

the site was a military camp, and that it housed the

Soviet 108th Motorized Rifle Division, was not gained

via satellite imagery: it was collateral information,

openly available, that aided him in his photointerpretation. Second, the size of an individual vehicle

~ ASS-that no two ~lelds are close enough to fit into the same picture. In facti near cities two or three airfields might exist in the

same Landsat scene. However, this effect is not strong enough to alter the conclusions of this calculation. Skorve’s 17-picture Landsat Kola

atlas shows an average of only slightly more than one airbase per picture (not counting duplicate views of the same base in overlapping pictures)

even though Kola is a very militarized region and even though some pictures show as many as four or five bases.

~ Almazfacts fromAviarion Week and Space Technology, Oct. 8, 1990; area of the Sea of Japanffom 1990 World Almana c. Almaz’s image

processing facility in Moscow is projected to be able to handle about 100 images per day.

66 UN ~termtio~ Narcotics Control Board Report for 1990, 1/91.

ST Kennedy, op. cit., footnote 38.

@ A hectare is 10,OOO ~uare meters, or about 2.5 acres. An 80 x 80 meter pixel is thus 0.64 hectares in are% and itS boundaries wodd not

necessarily be aligned with those of the planted plot. Even adjacent small coca plantings may not add up to a discernible target because they

are owned by different growers, who cultivate them in different ways. Thus the signature of an unhamested field may be diluted by that of an

adjacent harvested field.
. . . . .

Appendix C-Military Uses of Civilian Remote Sensing Data I 159

Table C-6-Civilian Satellite Images of l&W-Type Targets

would make one think that a system with SPOT’s

resolution could not see vehicles, but Banner detected

their departure by the fact that they had been parked

together, aided by change analysis. In his own words:

Using SPOT imagery, with its spatial resolution of

10 m or more, all but the largest rnilitary vehicles will

be smaller than even a single image pixel. Nevertheless,

irnagery of this quality might provide some limited

evidence of large-scale migration of vehicles from an

area. . . . The red areas in the change image [an “after”

picture subtracted from a ‘‘before’ picture-OTA] are

indicative of dark-toned features that existed in 1987

but not in 1988. The thin lines . . . and smaller features

. . . might be vehicles parked in rows and next to a

building. The thicker red areas . . . might be vehicles

parked several rows deep. Although the spatial resolution of SPOT imagery is clearly insufficient to detect

individual vehicles, it might be able to detect changes

in orderly rows of vehicles. At the same time, other

possible explanations for the changes are apparent in

the imagery. For example, it could be tents or packing

crates that have been moved.69

For many purposes, the sudden departure of large

objects from a military base would be of great interest

even if one could not establish whether the objects

were crates, trucks, or tents. While Banner’s interest is

the verification of troop withdrawals amid the outbreak

of peace, the same technology and logic could be

applied to see troop arrivals, or the departure of troops

from their customary bases. This last item takes on

particular salience in the context of the indications and

warning mission. Perception of these aircraft and

vehicles at such low resolution would be vulnerable to

deceptions in which dummy equipment is substituted

for the real thing.70

Sensors capable of piercing clouds or darkness, such

as thermal infrared and radar sensors, could provide the

timely coverage that is particularly vital in the I&W

task This consideration is hardly second-order; the

Kola peninsula, for example, widely cited during the

Cold War in such terms as “the largest concentration

of military installations and hardware anywhere in the

world” 71 and therefore rating intensive I&W coverage, experiences overcast conditions 80 to 90 percent

of the time. Four-fifths of the peninsula lies above the

Arctic Circle and thus experiences round-the-clock

darkness part of the year. With “prevailing bad luck’

some targets in the peninsula went through a whole

year without presenting themselves to be photographed by J. Skorve’s civilian satellite survey .72

Combat Intelligence-Unlike the shipyards, airfields, and other targets of broad area search, the targets

of combat intelligence occupy sharply delimited areasthe battlefield and its environs. Thus when Air Force

planners looking at combined SPOT and Landsat

69 Al]en v.B-~r,@erhe&I~8i~~for Venfi”cation ad peacekeeping: Three s(~ies, prepar~ for the kIIIS Control ~d D~~t

Division (Ottawa, Ontario, Canada: External Affairs and International Trade Canada, 1991), pp. 2(P21.

70 R.V, Jona, Reflec~jonS on ~nte~~jgence @ndon, Eng~d: Wilm Heine~M Ltd, 1989), p. 123. h their second World WU <fle at

El Alamein+ the British deployed durnm y artillery and fooled the Germans, who eventually caught on only to be fooled again when real artillery

replaced the dummies!

T] Jo~ Jorgen Hoist, h tis preface to Skome’s The KokI Satellite ]~ge Atlas, p. 6.

72 Skone, op. cit., footnote 27, pp. 54-55.
160 I Remote Sensing From Space

pictures of a fertilizer plant in Al Qaim (Iraq) saw

antiaircraft installations around it and deduced that

they should bomb it,73 they were performing combat

intelligence, not broad area search. The antiaircraft

example also illustrates how the utility of nonresolvable or barely resolvable images can be enhanced by combining them with better images.74 For

example, the SMP 1987 picture of Chernobyl combines SPOT panchromatic imagery and Landsat thermal imagery, creating a useful view of the overheated

reactor. Remarkably, many U.S. military units, even

low-level commands, have the ability to combine

imagery in this way.75

Though, as mentioned above, Landsat often cannot

see roads, DIA has stated that ‘during preparations for

the ground war during Operation Desert Storm,

30-meter Landsat could have revealed ground scars

and track activity indicating the thrust into Iraq west of

Kuwait. ’ ’76 It has been claimed that both sides in the

Iran-Iraq war purchased SPOT images as a means of

gaining combat intelligence,77 so such concerns are

hardly misplaced. In the case of Desert Storm,

however, U.S. and French vendors did not sell to Iraq

after hostilities began.78

Use of even coarser resolution images may be

possible. A Singapore-based civilian aviation journal

has reported that:

Pictures from the domestically developed IRA-lA

B remote sensing, and INSAT-D weather satellites are

being used for photo-processing and weapon targeting

under a high priority defence project that is ushering

India into the era of satellite reconnaissance and

communication. When fully commissioned, this system will increase India’s capability for targeting its

cruise and ballistic missiles for counter-base and

counter-force operations, as well as giving the country’s armed services a near real-time theater reconnaissance and battle-damage assessment capability.

In modem warfare, part of combat intelligence is the

preparation of fighting men for particular missions.

The Air Force’s successful attempt to staunch the

massive Kuwaiti oil leak perpetrated by Saddam

Hussein near the end of the Gulf War was rehearsed in

simulators using SPOT data.79 Formulation of databases to drive simulations used for training and

mission planning represents an emergent use of

remotely sensed civilian data. DIA has shown mem73 Cheud, op. cit., footnote 40, p. 4. This is probably the same well-protected ‘fetitier plant’ mentioned by Gordon on p. 30 of the June

26, 1992 testimony. For more on the fascinating art of photointerpretatio~ see OTA’S Verification Technologies: Cooperative Aerial

Survelliance in International Agreements.

74 ~p~ciple, an ~age’s ~solutlon co~d be improved by combining it with another image of Wud quati~, as long as the P~el bound~es

fell in different places on the two images (as would be almost guaranteed to happen.)

75 D, Brian Gordoq Chairma % TacticaJ and Military Multispectral Requirements Working Group, Defense Intelligence Agency, testimony

of hearings before the House Committee on Science, Space and Technology and the Permanent Select Committee on Intelligence, 102d

Congress, 1st sessio~ June 26, 1991. Scientific, Mititary, and Civilian Applications of the Landsat Program, p. 29.

76 Ibid., p. 56.

77 che~d, op. cit., footnote 48, p. 5.

78 Gordo~ op. cit., foomote 75, written response to questions inserted fOr the rword, P. 57.

79 Ibid., p. 31.
Appendix &Military Uses of Civilian Remote Sensing Data I 161

bers of Congress a few minutes of video tape

portraying a simulated pilot’s eye view of a flyaround

of Kuwait City and the neighboring Faylakah Island.

Landsat, SPOT, and Resurs-F images were combined

to create this tape.80 A published example shows how

an original SPOT picture of Baghdad can be turned

into a pilot ’s-eye view of the approach to a target,

complete with antiaircraft guns and annotations showing the locations of sites to avoid hitting, such as

schools and mosques.81

An important part of combat intelligence relates to

MC&G: the creation of databases for guidance systems. While the creation of map patches used by

TERCOM, for example, could well be categorized as

MC&G, the scenes used by the pilot or DSMAC

(Digital Scene Matching and Correlation) properly

belong to the realm of combat intelligence.

As mentioned in the description of the nascent

Indian capabilities, the combat intelligence mission

continues after the attack is made. Bomb damage

assessment must be performed to see if the target

merits another attack. The entry in table C-7 regarding

the damaged reactor at Chernobyl represents a possible

bomb damage assessment mission, but the reader

should be aware that bomb damage assessment is

notoriously difficult even with the best of sensors, and

that civilian satellites are unlikely to play any appreciable role in bomb damage assessment in the foreseeable future. 82

In performing the combat intelligence mission

during coalition warfare such as that prosecuted by our

side during the war with Iraq, civilian satellites have

the advantage that their product can be released to

foreigners allied with the United States.83 It can also be

distributed near the front without fear of compromising the capabilities of highly classified systems if

combat intelligence documents are captured.

Arms Control Agreement Monitoring—’’Politics, ’ as Prince Bismarck said, ‘‘is the art of the

possible. ”84 For this reason, arms control agreements

are, to a large degree, crafted so as to be verifiable at

the limits of available technology .85 The SALT arms

control agreements

86 dealt with large objects such as

submarin es and missile silos. President Jimmy Carter

said, during the SALT era, that “Photoreconnaissance

satellites have become an important stabilizing factor

in world affairs in the monitoring of arms control

agreements. ’87 Increased arms control ambitions and

improved verification technology (as well as the

newfound acceptability of on-site inspection) now

combine to create agreements such as START, in

which constraints are applied to the payloads of

missiles deployed underground.

Present-day civilian satellites seem hardly capable

of verifying even yesterday’s arms control agreements.

For example, SALT specified that an intercontinental

ballistic missile (ICBM) would be deemed to be of a

“new type” if its dimensions (or, more accurately, the

dimensions of its silo launcher) differed from those of

its predecessor by more than 5 Percent.** Such a

tolerance---less than 1 meter89cannot be measured

w Ibid., p. 37.

81 Covault, Op. cit., footnote 59, pp. 61, 63.

82 Swre- of Defeme Dick Cheney, Conduct of the persian Gulf Conflict: An Interim Report to Congress, p. 14-2, and conduct of the

Persian Guy War: Final Report to Congress, pp. C-14 to C- 16.

83 Gordo~ op. cit., footnote 75, p. 28.

84 The O@ord Dlctiomry of Quo[afzon$, 4th editioq Angela partington (~.) (oxford, ~: Oxford University press, 1992), p. 84.

85 Ide~ly, tw~olo= ~ou]d be develo~ ~th an eye to -gv~fiable those agr~en~ that wme desirable for other reasons. See U.S.

Congress, Office of Technology Assessment, Verification Technologies: Managing Research and Development for Cooperative Arms Control

Monitoring Measures, OTA-ISC-488 (Washington DC: U.S. Government Printing Office, May 1991).

66 From t~y~s perspective S~T I includ~ the signed ~d ra~i~ MM Treaty and tie ~terirn Agreement on Offensive AllIIS. SfiT H

was signed but never ratified. All continue to figure in today’s arms-control compliance debate, even though time spans stated in the Interim

Agreement and SALT II have now elapsed. START, signed but not yet ratified, subsumes many of the SALT provisions that have lived on

past their officiat lifetimes.

.87 SpeWh by fiesldent JimmyCarter, at the Kemedy Space Center, Oct. 1, 1978.

88 ~ter, Comlderab]e contention would ~se over tie quesiton of whether (his proviso ~fe~d to finear dimensions Or tO VOIUme. b tie

present context, this important consideration is irrelevant.

89 Not because 5 ~rcent of the dlametm is less tin a meter, but ~~use tie difference between WI a~owable 5 p~cent change and an illegal

6 percent change is less than 1 meter. This important point is made by Zimmerrnam op. cit., footnote 22, p. 41.
162 I Remote Sensing From Space

by today’s civilian satellites, though they could see the

construction equipment present during silo modification if they looked at the right time.

However, civilian remote sensing satellites are not

without utility in arms control verification (table C-8).

They can, for example, locate facilities deserving

greater attention from other treaty-monitoring systems, including onsite inspection. Jasani’s analysis of

SS-25 sites in the former Soviet Union brings to light

several discrepancies between the site plans submitted

by the Soviet side and the actual layouts of the sites.

The INF Treaty protocol allows for the revision of data

submitted in the data exchanges (Article IX.3), and

SPOT-derived indications that such revision was in

order could be freely shown to CIS representatives.

| The View From the Other Side

So far this analysis has been one-sided, addressing

only the benefits the U.S. military could derive from

civilian remote sensing satellites. In this section we

shall turn to the view from the other side—ways in

which an adversary could diminish the utility of these

satellites to the United States military, and ways in

which he could avail himself of their services to the

military detriment of the United States.

CAMOUFLAGE, CONCEALMENT, AND DECEPTION

(CC&D)90

Sun-Tzu Wu, the ancient Chinese military writer,

maintained that deception was the cornerstone of

successful military planning. More recently, the erstwhile Soviet military emphasized the role of maskirovka, a military art grouping under one tarpaulin the

Western notions of camouflage, concealment, and

deception. 9l The Soviets’ confederated successors and

Third-World understudies doubtless attach similar

importance to these dissimulative practices.

“Camouflage is the technique of hiding from view

that which is physically present,”92 and includes the

mottled paint and nets festooned with fresh-cut branches

familiar to us from war movies and television, and

other techniques of making the objects of interest

blend in with the ground.

“Concealment” includes other means of avoiding

detection. In the case of radar satellites such as Almaz,

concealment could be accomplished by jamming—

beaming junk radio waves of the correct frequency at

the satellite. Such jamming would ‘‘appear as dark

static interference on imagery and [would] usually

cover the entire section of imagery in the area of

coverage. ’93

“Deception is the technique of making what is

physically present appear to be something different. ’94 It includes the use of dummies and decoys.

‘‘Dummies are imitations of actual objects or installations, usually composed of dummy weapons, emplacements, vehicles, and equipment, They are designed to

simulate real activity and draw fire away from

camouflaged or concealed activities. Decoys are lures

located in logical military positions but far enough

from actual targets to prevent fire directed against them

from hitting the real sites, ’ ’95 Interestingly, a decoy or

dummy must—for realism’s sake-be camouflaged,

though not so well as to prevent it from being seen!

Military applications of civilian remote sensing that

use the sensors’ utmost spatial resolution and rely

heavily on the deductive powers of the end user could

be deceived by the crudest of CC&D operations:

10-meter resolution could hardly hope to discriminate

a decent dummy from the real thing. However, civilian

satellites’ spectral resolution could come to the rescue:

painted-on foliage might look realistic in the visiblelight portion of the spectrum, but only the fanciest

camouflage nets maintain their deception into the near

infrared. Thermal infrared provides yet another view,

one very difficult to mask. The detection of these, and

of CC&D efforts in general, is aided greatly if

comparative covers (multiple images of the same

region) are available: comparison of a current image to

an archive picture taken much earlier immediately

LX) sm ~~o OTA~S VerificationTechnologies, op. cit. footnote 19, esp=idly ch. 3 and WP. B.

!31 s=, for ~mple, Cmufiuge: A Soviet View, ~oviet Milltaq Th~~ght, no. 22, ~mlated and published under the auspices of the U.S.

Air Force (Vhshingtom DC: U.S. Government Frinting OffIce, 1989). This volume is comprised of two Soviet books on maskirovka.

~ Soldier’s ~n~ Skill Level I, op. cit., footnote 21, p. 2-298.

93 Ibid., p. 2-484.

~ Ibid., p. 2-298.

93 Ibid., p. 2-236.
Appendix &Military Uses of Civilian Remote Sensing Data I 163

Table C-8-Civilian Satellite Images of Arms-Control Targets

Installation Treaty Satellite Source

the United Nations Department of Disarmament Affairs.

focuses attention on those features that are different,

alerting the interpreter to the fact that they might be

parts of a CC&D operation. The U.S. Army’s manual

for the beginning image analyst counsels: “Be suspicious of everything in the photograph that does not

have an explanation. ”9b

SPYING ON AMERICA

Under current policies, vendors will sell satellite

pictures of the United States to anybody who has the

money. While one can imagine various ways in which

such information could be used in the realm of

economic competition (prediction of crop yields, for

example), it is at first difficult to imagine ways in

which satellite imagery could further a military effort

against the United States. Information about the United

States is relatively easy to come by, and few potential

enemies have the ability to reach U.S. territory with

anything but a terrorist attack. (Even so, terrorist

attacks against the United States to date have occurred

at foreign airports, bases, or embassies. Additionally,

some of these attacks have required information that

could not be obtained by satellite, such as the internal

layout and security procedures of airline terminals.)

However, remotely sensed data from civilian imaging satellites could be used in certain ways inimical to

the United States.

Obtaining Accurate Location of Target-In the

near future, even a technologically unprepossessing

foe may be able to fit primitive cruise missiles (perhaps

no more complicated that the German V- 1s of 50 years

ago) with inexpensive, and yet highly accurate, guidance equipment using the universally accessible Global

w ~id., p. 2-281, as welt as numerous Other pagw.
164 I Remote Sensing From Space

Positioning System (GPS).97 Such accurate guidance

engenders a need for accurate knowledge of the

target’s location, because otherwise the accurate guidance is wasted. A typical target would be a building on

a military base. A SPOT or other image with good

metric data would allow for accurate GPS-based

navigation of the missile to the target.

Testing CC&D Methods-The practitioner of

CC&D, especially that directed against civilian imaging satellites, could test the efficacy of his methods by

requesting imagery of test targets, in his own territory,

incorporating his CC&D methods. In this way he

would be spying not on America’s territory, but on her

civilian detection capabilities vis-a-vis his denial

techniques.

Observation of Denied Areas---Despite America’s

overall character as an open society, there exist many

good-sized military reservations to which access is

denied. These could be probed through the use of

satellite photography.

| Market Motives and Military Missions

Technical progress is possible in all facets of remote

sensing technology+ specially in the four basic

parameters, spatial and spectral coverage and resolution—but civilian satellites’ designs are based on

tradeoffs among these and other desirable characteristics. These tradeoffs are made on the basis of civilian

science and commercial demands. Assuming that the

design of future systems is not shaped by military

requirements recycled into the commercial marketplace,

will civilian satellites, through technical progress,

become ever-more suited to military missions?

Almost any technological improvement in civilian

remote sensing technology will have some military

benefit, but the principle defect of civilian satellites for

military remote sensing-their untimely responsiveness—is unlikely to be remedied unless the designers

of civilian satellites accede explicitly to their military

customers’ demands. In the civilian world, timeliness

measured in days or weeks is perfectly acceptable for

most applications: geology and topography aren’t

going anywhere, and pictures of crops, evanescent

though their subjects may be, can often be scheduled

far in advance because planting and harvesting occur

on strict schedules.

Interestingly, arms control missions-in which

civilian satellites do not now perform conspicuously

well because of their limited resolutio~may be very

well-served by the civilian satellites of the future.

Market forces will almost certainly push satellites to

finer resolutions, and the arms control mission requires

no greater a timeliness than do many civilian missions

because arms control verification takes place on a

diplomatic, not a military, time scale. However, the

high resolutions desired by the arms<ontrol customer

would have little use for nonmilitary missions and

would pressure the satellite’s design away from the

broad-area coverage desired for the nonmilitary missions.

Might a satellite optimized for military uses be built

and launched as a commercial venture? Such a

“mercsat’ is already in the advanced planning stage:

a U.S. company has proposed to build, launch, and

operate a satellite for a foreign customer, providing

data with l-meter resolution98 and other such deals

have been contemplated.99 This arrangement is not an

export of anything but the data, because the foreign

customer would at no time lay hands on the satellite or

its

|

1.

2.

controls.

Findings

Civilian satellites such as Landsat, but most notably

SPOT and Resurs-F, have considerable military

utility. Imagery from these assets can and has been

used to support military operations. Their utility for

arms control is limited. Technical progress, especially in spatial and spectral resolution, continues to

improve the military utility of successive generations of these satellites.

Civilian satellites’ use to date for military reconnaissance suggests that post-processing, skilled

interpretation, and the use of collateral information

can make even fuzzy pictures informative. For this

reason, the civilian satellites’ in reconnaissance

exceeds that which might be expected on the basis

of ground resolution—a simplistic, though custom-

~ K~s@ Tsip:s, New York Times, Apr. 1, l~z, P. ~5.

98$ ‘Efitw Want TO Buy U.S. Spy Satellite,” Space News, vol. 3, No. 43 (Nov. 16-22, 1992), p. 1.

99 wil~ J. Bm~, “3 Natiom Seek To Buy Spy Satellita, Causing a pOhW ~t kl U.S.,’ New York Times, Nov. 23, 1992, p. A7.
.. .

Appendix C-Military Uses of Civilian Remote Sensing Data I 165

ary, measure of capability-and the highly conservative rules of thumb normally used to relate it to

suitability for particular reconnaissance tasks.

3. However, reconnaissance missions’ requirements

for timeliness often exceed the current capabilities

of civilian satellite systems. Because civilian missions’ timeliness requirements are relatively lax

compared to military ones, civilian satellite systems will continue to fall short in this regard unless

they begin to cater expressly to the military market.

4. Foreign ownership of the most capable civilian

remote-imaging satellites brings into play the usual

foreign-source considerations: the United States

could be denied access to imagery for political

reasons, and the assets could well be operated in

ways inimical to U.S. interests, and so on. Restoration of U.S. technical dominance in the commercial

remote-imaging field could allay these fears.

5. Though the possibility of using Landsat, SPOT, and

Resurs-F data to sense enemy forces springs most

readily to mind when one speaks of military uses of

civilian sensing, the military needs accurate meteorological data as well. These, too, come from

civilian satellites as well as from the military’s own

weather satellites.

6. Mapping—including precise measurement of the

geoid itself—is a civilian mission with important

military applications. These applications include

simulation, training, and the guidance of automated

weapons. Mapping to date falls short of what most

people might imagine, both in terms of coverage

and of precision. A more capable system, perhaps

a interferometric SAR, would remedy this shortfall.

7. Many uses, civilian and military, of remotely

sensed Earth data require that one be able to mix,

match, compare , contrast, combine, add ,

or subtract data from different sources. While such

operations are hampered by the plethora of different

formats and media in which the data are collected

and stored, this lack of standardization poses no

insuperable obstacles-data from such diverse

sources as Landsat, SPOT, and even the Russian

Almaz are routinely combined once an initial

learning period has passed. Moreover, in recent

action by the executive branch, the Secretary of

Defense and the Director of Central Intelligence

have chartered a new Central Imagery Office.lm

Specifically included in its responsibilities are the

areas of imagery formats, standardization, and

interoperability.

| Issues for Congress

1. Standardization: Is there need for Federal action

to regularize Earth data reporting formats and

media? If so, ought action to be taken by the

executive or the legislative branch?

2. Competitiveness: Civilian satellites such as Landsat, but most notably SPOT and Resurs-F, have

considerable military utility. Imagery from these

assets can and has been used to support military

operations. Is potential loss of this military market,

by EOSAT to foreign suppliers a national competitiveness concern?

3. Threats to Security: The United States could be

denied access to imagery for political reasons, and

the assets could well be operated in ways inimical

to U.S. interests. Putting the shoe on the other foot,

other countries could use civilian images of the

United States or its foreign military deployments to

plan their attacks. Can the U. S., through its

Landsat program, take action to prevent or deter

such operation?

4. Entanglement: Foreign belligerents can, and probably have, buy Landsat pictures (or use GPS data)

to further their wars against each other. They might

even buy them to prepare for a war (or terrorism)

against the United States or its allies, fulfilling

Lenin’s prophecy that the capitalist would sell the

rope that would be used to hang him. How should

the United States respond to indications that such

activity might be in the offing? Could the United

States detect that such use of Landsat images was

being made?

lm Dep~ent of Defense Directive 5105.56, MY 6, 1992.
Appendix D:

Non-U.S. Earth

Observation

Satellite

Programs

M

any countries routinely use satellite remote sensing for land

planning, weather forecasting, environmental monitoring,

and other purposes. Most of these countries share data with

the United States, neighboring countries, and international

organizations. This appendix summarizes the remote sensing systems

of other countries and organizations.

EUROPE

Development of remote sensing spacecraft in Europe is under the

management of the European Space Agency (ESA), a consortium of 13

member states-Austria, Belgium, Denmark, Germany, France, Ireland, Italy, The Netherlands, Norway, Spain, Sweden, Switzerland, and

the United Kingdom. Finland has ESA Associate Member status, and

there is an agreement for close cooperation with Canada. Since ESA’S

inception in May 1975, it has pursued an Earth observation program.

Meteosat/MOP

ESA’S Earth observation program was based initially on a series of

pre-operational meteorological satellites, called Meteosat. 1 The first—

Meteosat l—was launched in November 1977 and placed in a

geostationary orbit, but suffered an onboard imaging failure after two

years of service. A second pre-operational Meteosat was launched in

June 1981. Yet another of the series, a Meteosat P2 (a refurbished

engineering model for the pre-operational series), was deployed in June

1988.

The first spacecraft of the Meteosat Operational Programme (MOP1) was launched in March 1989 and carried four independent imaging

‘ What’s the Forecast? The European Space Meteorology Operational Programme,

European Space Agency, ESA F-01, 2nd Edition, ESTEC, Noordwijk, The Netherlands,

January 1989.

167
168 I Remote Sensing From Space

channels. MOP-2 was orbited in March 1991,2 and

MOP-3, the sixth spacecraft of the Meteosat series,

will be ready for launch in late 1993. It will have an

expected seven-year life.

The MOP satellites are developed and operated by

ESA on behalf of the European Organisation for the

Exploitation of Meteorological Satellites (Eumetsat).3

Formed in January 1987, Eumetsat is composed of 16

member states: Belgium, Denmark, Finland, France,

Germany, Greece, Ireland, Italy, The Netherlands,

Norway, Portugal, Spain, Sweden, Switzerland, Turkey, and the United Kingdom. Eumetsat manages the

operational Meteosat program, while ESA procures,

launches and operates the spacecraft on a reimbursable

basis for Eumetsat. In general, the Meteosat/MOP

spacecraft design, instrumentation, and operation are

similar to the U.S. NOAA SMS/GOES spacecraft. The

spin-stabilized spacecraft carry:

●

●

a visible-infrared radiometer to provide highquality day/night cloud cover data and to take

radiance temperatures of the Earth’s atmosphere,

and

a meteorological data collection system to disseminate image data to user stations, to collect

data from various Earth-based platforms, and to

relay data from polar-orbiting satellites.

The satellite’s principal payload is a high-resolution

radiometer. This instrument allows imaging of the

Earth in three spectral bands: visible light; thermal

infrared; and infrared “water vapor” (see table D-l).

Meteosat spacecraft are positioned to survey the

whole of Europe, as well as most parts of Africa, the

Middle East and the Atlantic Ocean. The satellites

relay images and data to the Meteosat Operations

Control Centre within ESA’S Space Operations Control Centre in Darmstadt, Germany. The Meteorological Information Extraction Centre, located within the

Meteosat control center, distributes the satellite data to

various users.

Meteosat is part of a program involving four

geostationary satellites (nominally, two American, one

European and one Japanese) that constitutes the basis

of the World Weather Watch of the Global Atmosphere Research Program. Data from the Meteosat

series is received in Europe directly from the satellites

and relayed to the United States.4 Meteosat data are

used in various international research projects. Recently, as the result of an agreement between Eumetsat

and NOAA, ESA moved Meteosat to a position of

75oW longitude in order to provide better coverage of

the United States (see ch. 3).5

Eumetsat

Eumetsat manages the Meteosat series of geostationary satellites and is NOAA’s partner in the

follow-on NOAA-K, L, and M satellites. Eumetsat is

headquartered in Darmstadt, Germany, and is establishing a remote sensing ground infrastructure, including data processing and archives. Eumetsat is developing user access policies for full and open access to data

in the meteorological tradition, but is also providing

incentive for European countries to become members

and share the financial burden of maintaining and

improving operational meteorological services. Nonmember countries are likely to pay for data through

royalties or license fees. Encryption of satellite data

would allow enforcement of any Eumetsat pricing

policies. 6

The Meteorological Information Extraction Centre

in Darmstadt develops products in support of the

International Satellite Cloud Climatology Project, with

selected products supplied to the Global Telecommunications System of the World Meteorological Organization (WMO) as part of the World Weather Watch.

These data are archived at ESA’S Operations Control

Centre, which also controls and operates the Meteosat

satellites for Eumetsat.

European Remote Sensing Satellite (ERS)

The ERS-1 satellite was launched into polar orbit by

an Ariane booster in July 1991 and was declared

2 MOP-2: A4eteosat Operational Programme, ESA/EUMETSAT, European Space Agency, ESA C-6, January 1991.

3 c ~ESA H~d~ over Met~~at.5 to E~TSAT, ” ESA News Release, No. 2, EuropMn Space Agency, Paris, France, Jan. 14, 1992.

d NOAA archives Meteosat data for use in the U.S.

5< *Metmsat.3 t. tie Rescue , . . of NOM,” in ESA Newsletter, No. 9, European Space Agency, Paris, France, November 1991.

6 Lisa R. Shaffer, “The Data Management Challenge,” presented at Annual Meeting of the American Association for the Advancement

of Science, Washington, DC, February 1991.
Appendix D-Non-US. Earth Observation Satellite Programs I 169

Table D-l—Spectral Coverage of Selected Remote Sensing Satellites

* Antlclpatcd launch
170 I Remote Sensing From Space

Table D-l-Spectral Coverage of Selected Remote Sensing Satellites-Continued

7 c t~s-I Now Ddi3KxI Operational, “ ESA News Release, European Space Agency, Paris, France, Jan. 27, 1992.
..

Appendix D—Non-U.S. Earth Observation Satellite Programs I 171

Satellite

Speectral Coverage

Ultraviolet

Blue

Green

Red

Near Infrared

Mid Infrared

Thermal IR

Microwave

Panchrornatic

Meteor 2

CIS

Numerous

NIA

NIA

.50-,70

NIA

NIA

8-12

(8 km rcs.)

141-18,7

(30 km rcs)

NIA

N/JA

Meteor-3

CIS

8-91

.5 km

2600 km

.25-,38

(3-5 km rcs)

N/A

.50-,80

NIA

NIA

10-12.50

11.5012.50

9.65-187

(42 km rcs)

NIA

N/A

CIS

2.90

N/A

NIA

50-.60

60-70 (2

channels)

70-80

.80-1 10

1050-1150

1150-1250

NIA

.8 cm band/6-

15 km rcs,

3.15 cm

band/l -2 km

rcs

NIA

CIS

4-88

10-30 m

180 km

N/A

NIA

.50-60

60-70

NIA

.70-80

80-1.10

104-126

.8-4.5 cm

band

17-90 km rcs

9,2 cm SAR

200 m rcs

N/A

ClS

5-91,

6 launched in

1990-91

10-30 m

180 km

NIA

NIA

NIA

.63-70 (6

channels,

NIA

N/A

N/A

NIA

N/A

1.1 km

NIA

.48-53

.53-.58

.58-68

.725 -1.10

10.5 -12.5

NIA

N/A

N/A

IRS 1-B

India

3-88/8-9 1

72 m

148 km

N/A

45-.52

52-59

62-68

.77-86

NIA

N/A

NIA

365 m

7425 km
172 I Remote Sensing From Space

operational six months later.7 Operating from a sunsynchronous, near-polar orbit, ERS-1 is the largest and

most complex of ESA’S Earth observation satellites.8

The ERS-1 platform is based on a design developed for

the French SPOT program.

From a 98.5-degree orbit at 785-km altitude, ERS-1

makes use of a synthetic aperture radar (SAR) to study

the relationships between the oceans, ice, land, and the

atmosphere. The SAR’S all-weather, day-and-night

sensing capability is critical for polar areas that are

frequently obscured by clouds, fog, or long periods of

darkness.

The primary mission objectives of ERS-1 include:9

●

●

●

●

●

improving understanding of oceans/atmosphere

interactions in climatic models;

advancing the knowledge of ocean circulation

and transfer of energy;

providing more reliable estimates of the mass of

the Arctic and Antarctic ice sheets;

enhancing the monitoring of pollution and dynamic coastal processes;

improving the detection and management of land

use change.

Data from ERS-1 allows researchers to:

●

●

●

●

●

study ocean circulation and global wind/wave

relationships;

monitor ice and iceberg distribution;

more accurately determine the ocean geode;

assist in short and medium-term weather forecasting, including the determination of wind speed;

locate pelagic fish through monitoring of ocean

temperature fronts.

The spacecraft’s synthetic aperture radar provides

all-weather, high-resolution (30 meters) imagery in

100-km-wide swaths over oceans, polar regions, and

land. A core suite of onboard microwave sensors is

supported by additional instruments (see table D-l).

ESA has developed a ground system for ERS-1,

including centers for receiving, processing, validating,

disseminating and archiving data:

●

●

●

●

●

●

the Mission Management and Control Centre

(MMCC) in Darmstadt, Germany, which carries

out all satellite operations control and management, including instrument operational scheduling;

ESA ground stations at Kiruna (Sweden), Fucino

(Italy), Gatineau and Prince Albert (Canada), and

Maspalomas (Canary Islands, Spain) which provide the main network for data acquisition and the

processing/dissemination of fast-delivery products;

national ground stations around the world receive ERS-1 high-rate data by arrangement with

ESA, extending the coverage potential of the

high-resolution SAR imaging mission. One such

ground station, funded by NASA, is the Alaska

SAR facility at the University of Alaska Fairbanks. This facility, combined with two SAR

stations in Canada and one in Sweden, provide

nearly complete satellite coverage of Alaska and

the Arctic for the first time; 10

the Earthnet ERS-1 Central Facility (EECF) in

Italy, which carries out all user interface functions, including cataloging, handling of user

requests, payload operation planning, scheduling

of data processing and dissemination, quality

control of data products and sensor performance

monitoring;

Processing and Archiving Facilities (PAFs) located in the United Kingdom, Germany, France,

and Italy which are the main centers for the

generation of off-line precision products and the

archiving of ERS-1 data and products;

user centers and individuals, such as national and

international meteorological services, oceanographic institutes, and various research centers.

7 “ERS- 1 Now Declared operational, “ ESA News Release, European Space Agency, Paris, France, Jan. 27, 1992.

g The Data Book of ERS-1: The European Renwte Sensing Satellite, ESA BR-75, European Space Agency Publications Divisio% ES’I’EC,

Noordwijk, The Netherlands, 1991. Pam Vass, and Malcolm Handoll. UK ERS-1 Reference Manual, DC-MA-EOS-ED-0001, Issue No. 1.0,

Royal Aerospace Establishment, Farnboroughj UK, January 1991.

9 R. Holdaway, “UK Instruments for Mission to Planet Earth, ” presented at 42nd Congress of the International Astronautical Federation

OAF), (M-91-139), Montre~, Canada, Oct. 5-11, 1991; Ian pinker, “Satellite Sees All,” Space, vol. 7, No. 6, November/December 1991,

pp. 8-12.

10 ‘ ‘satellite Facility Ready as ERS-1 b~chti,” Geoph~~sicaZInstitute Quarter/y, vol. 9, Nos. 3 & 4, Fairbanks, AlaslciL summer 1991.
Appendix D—Non-U.S. Earth Observation Satellite Programs I 173

An ERS-2 spacecraft, a follow-on mission to ERS-1,

is an approved ESA project for launch in 1994, thereby

offering uninterrupted data collection from 1991 until

the initiation of ESA’S Polar Orbit Earth Observation

Missions (POEM) program scheduled to begin orbital

operations in 1998. ESA will first launch Envisat, an

experimental ecological monitoring satellite. Later,

around 2000, ESA will launch the Metop satellite,

designed to provide operational meteorological data.

Eumetsat will provide data from the Metop system in

cooperation with NOAA (see ch. 3 and ch. 8), ERS-2,

along with ERS-1 instrumentation, will carry the

Global Ozone Monitoring Experiment package to

analyze atmospheric chemistry, using mediumresolution spectrometry in the ultraviolet and visible

regions of the spectrum to examine ozone and other

chemical substances in the troposphere and stratosphere.

The ERSC Consortium (Eurimage, Radarsat International, and SPOT Image Consortium) is responsible

for worldwide commercial distribution of ERS-1 data

and products to users. Eurimage is owned by four

companies: Telespazio (Italy), Dornier (Germany),

Satimage (Sweden), and British Aerospace (United

Kingdom), with each as a 25 percent shareholder.

Eurimage is responsible for the distribution of all ESA

products within Europe and the Middle East, Radarsat

distributes products in North America. SPOT is

responsible for distribution to remaining world markets. 11

The European Space Agency’s remote sensing data

management program is called Earthnet. 12 This group

is headquartered in Frascati, Italy, at the European

Scientific Research Institution (ESRIN).13 ESA primarily serves European users, but data from Earthnet

are available to any user for a price, either directly or

through Eurimage. Earthnet provides basic remote

sensing data in digital and photographic format, while

higher level products are turned over to value-added

firms for production and distribution. Users from

countries who contributed to the cost of the program

are given preferential prices.

FRANCE

Systeme Probatoire d’Observation de la Terre

(SPOT)

The SPOT-1 spacecraft was launched in February

1986 by Centre National D’Etudes Spatiales (CNES),

the French space agency, as an operational, commercial satellite. The SPOT program represents a $1.7

billion investment through the end of the decade.14

CNES acts as overall program leader and manager with

full responsibility for satellite launches and orbital

control and related funding. Government/industry

organizations participating in the SPOT program are led

by CNES, the Swedish Space Corporation in Sweden,

and the Societe Nationale d’Investissement of Belgium.

SPOT-1 was placed in a sun-synchronous, nearpolar orbit of 824 X 829 km altitude, with a design

lifetime of two years. Every 369 revolutions around the

Earth (every 26 days), SPOT-1 arrives at the same

place over the globe. SPOT-1 carries twin pushbroom

CCD High Resolution Visible (HRV) Imaging Instruments. The HRV can point up to 27 degrees off the

satellite track, allowing the satellite to reimage places

on the surface within 2 or 3 days. Also onboard are two

magnetic tape data recorders and a telemetry transmitter. Until December 1990, the HRV observed in three

spectral bands in multispectral mode with a swath

width (nadir viewing) of 60 km; and in panchromatic

mode with a swath width of 60 km (see table D-l).

SPOT-1 attained a ground resolution of 20 meters in

multispectral mode, and 10 meters in panchromatic

mode. SPOT-1 off-nadir viewing yielded stereoscopic pairs of images of a given area during successive satellite passes. A standard SPOT-1 scene covers

an area 60 X 60 km.

SPOT-1 lifetime of two years stretched until its

first retirement in 1990, after suffering from a failing

11 Peter de Selding, ‘‘ESA Sigm Long-awaited Imagery Sales Deal, ’ Space New)s, vol. 3, No. 5, Feb. 1016, 1992, pp. 4; “ESA Initiates

Commercd Distribution of ERS-1 Data,” ESA News Refeuse, No. 8, European Space Agency, Paris, France, Feb. 7, 1992.

]Z s~fer, op, cit., fOOtnOte 6“

13 E-et Wm ongl~ly es~blished t. rwelve and me availab]e EM obsemation dam from non-ESA satellites, such as Landsat and

MOS, Tires-N, Seasat, HCMM, Nimbus-7, and SPOT, but is now the focal point for ESA remote sensing data mamgemen~ with substantial

ERS-1 responsibilities.

14 ~unc~rng SPOT 2.]nfor~tion Fi/e, Centre Nation~ d’Etudes Spatiales, Toulouse France, 1989; ‘ ‘France: Remote sensing ~~~’

in Science and Technology perspechves, Foreign Broadcast Information Service, vol. 5, No. 4, Apr. 30, 1990, pp. 11-12.
174 I Remote Sensing From Space

onboard tape recording system. The satellite was

reactivated in March 1992,15 with ground operators

making use of SPOT-1 imaging instruments and

real-time acquisition mode. By providing operational

service, SPOT-1 is being used to meet a data demand

during the northern hemisphere growing season, and to

reduce the workload on SPOT-2 over high-demand

areas.

SPOT-2 was launched in January 1990 as a replica

of SPOT-1. Only minor modifications were used in the

building of SPOT-2: use of improved charge coupled

devices (CCD); improved calibration housing; and the

addition of a high-precision orbit determination system.

A SPOT-3 has been built and is ready for launch

when needed, to assure continuity of SPOT services

until the year 2000. SPOT-3 will exhibit the same

capability as the first two SPOT spacecraft, but will

also carry a Polar Ozone and Aerosol Measurement

instrument for the USAF Space Test Program.

SPOT-4 has been approved for development, and

should be ready in 1994 in the event of a SPOT-3

failure. SPOT-4 is considered the first of the secondgeneration Earth observation platform series. SPOT 4

will be built around an improved platform that will

have an expected operational life of five years.16

SPOT-4 will have increased on-board instrumentation

capacity and performance, including more than double

the electric, computing, and recording capacity. The

High Resolution Visible Imaging Sensors carried

onboard SPOTS 1-3 are to be upgraded to High

Resolution Visible Infra-Red by the addition of a

mid-infrared band (1.58-1 .75 microns) .17

Beyond SPOT-4, discussions are underway concerning synthetic aperture radar and optical instruments, such as a new stereo, high-resolution imager. 18

CNES is studying the potential for developing a

microwave subfamily within the SPOT family of

remote sensing satellites using the SPOT-4 spacecraft

bus. Using a synthetic aperture radar, such a spacecraft

could be introduced in parallel with the optical SPOT

family after 2000.19 The radar-carrying satellite would

be operated on a commercial basis and would maximize use of the SPOT receiving station network, as

well as commercial and product delivery facilities.

SPOT satellites transmit data to an expanding

network of receiving stations. Major space imagery

receiving stations are located at Toulouse, France, and

in Kiruna, Sweden. Other receiving stations capable of

receiving SPOT data are located in Canada, India,

Brazil, Thailand, Japan, Pakistan, South Africa, and

Saudi Arabia, as well as the European Space Agency’s

station in the Canary Islands, Spain. Actual operation

of the satellite is carried out by CNES at SPOT mission

control in Toulouse.

Formed in 1978 and located in Reston, Virginia,

SPOT Image, Inc. provides U.S. businesses, universities, and government agencies a range of products and

services based on SPOT data.20The worldwide commercial headquarters, SPOT Image, S. A., is anchored

in France, with SPOT Imaging Services in Australia

and SPOT Asia located in Singapore. SPOT distributors are present in over 50 countries around the world.

Helios

Common with the development of a SPOT-4 is the

Helios reconnaissance satellite being built for the

French Ministry of Defense.21 This satellite received

approval in 1988. Italy and Spain are partners in this

project, contributing 14 percent and 7 percent of the

funding, respectively. Helios will have a reported

resolution of about 1 m. Helios-1 should be ready for

launch in 1994, possibly followed 2 years later by

Helios-2.

15 f ~spoT. 1 Res~~ Operational Service, ” SPOT Image Co~oration Press Release, Restoq VA, Mar. 27, 1992.

16 J,M. Au&~, C. Bi~ard, and P. Ranzoli. ‘The SPOT MKII Bus, A Key to Earth Observation in the ‘90s, ’ presented at the 42nd COn@XS

of the International Aeronautical Federation (IAF-91-013), Montreal, Canada, Oct. 5-11, 1991.

IT c. Fra~er, AlfiBaudo~ et ~., ‘‘A Stereo, High Resolution Concept for the Future of the SPOT Program, ’ presented at the 42nd Congress

of the International Astronautical Federation (IAF-91-128), Montreal, Canada, Oct. 5-11, 1991.

18 D. Sewela, J.P. Durpaire et al., “GLOBSAT: A French Proposat for Earth Environment Monitoring from Polar orbi~” @F-91-120),

Montreal Canada, Oct. 5-11, 1991.

19 J.p. A~~es, D. Massome~ and O. Grosjmn. “A New Radar System for the French Program in the ‘00s,” presented at 40th Congress

of the International Astronautical Federation (IAF-89-124), Malaga, Spaim Oct. 7-13, 1989.

m Stephne Chenard, “SPOT’s Subsidized Success Story, “ in Space Markets, February 1990, pp. 102-103.

21 Ann~/ Report 1$290, Centre National D’Etudes Spatiales (CNES), Ptis, France, pp. 65-68.
Appendix D—Non-U.S. Earth Observation Satellite Programs [ 175

The Ministry of Defense has appointed CNES to act

as overall system architect for Helios and has given it

procurement responsibility for the Helios segment.

The Western European Union (WEU) has established

a facility in Torrejon, Spain, to analyze images from

SPOT and Landsat. It will also receive some imagery

from Helios.22

TOPEX/Poseidon

Launched in July 1992 aboard an Ariane booster,

TOPEX/Poseidon is studying the topography of the

ocean’s surface and ocean currents worldwide. The

project is a joint undertaking, initiated in September

1983 between France and the United States. The

spacecraft is the result of the merger of two similar

programs: NASA’s Ocean Topography Experiment

(TOPEX) and France’s CNES Poseidon experiment.

The launch marked the first time a NASA spacecraft

was launched by an Ariane booster.23 The satellite

should operate for at least three years and is comprised

of two French and five U.S. instruments: a NASA radar

altimeter; a NASA laser retroreflector assembly; a

NASA frequency reference unit; a NASA TOPEX

microwave radiometer; a Jet Propulsion Laboratory

global positioning system demonstration receiver; a

CNES solid state altimeter; and the CNES Determination d’Orbite et Radiopositionement Integre par Satellite (DORIS) receiver.

From its 1,334-km altitude, the TOPEX has a fixed

ground track that repeats every 127 circuits of Earth

(9.9 days). Using NASA tracking and data relay

satellites, as well as laser tracking from the ground, the

satellite’s orbit around the Earth can be pinpointed

within an accuracy of 13 centimeters. A comparison of

the distance between satellite and sea surface with the

distance between the satellite and the Earth’s center

allows for accurate topographic mapping of the ocean,

The U.S. radar altimeter operates with a prime

channel of 13.6 GHz in the Ku-band and a secondary

channel at 5.3 GHz in the C-band. The microwave

radiometer is a four-channel, three-frequency sensor

that operates at 18, 21, and 31 GHz to measure the

correction for the tropospheric water vapor content of

the altimeter nadir column to an accuracy of 1.2 cm.

The French radar altimeter is a single-frequency (13.65

GHz) experimental sensor, with an accuracy of about

2 cm. The CNES DORIS dual-frequency (401 and

2036 Mhz) dopplerreceiver achieves an accuracy of 10

cm.

Data received from the TOPEX/Poseidon will assist

in the World Ocean Circulation Experiment (WOCE),

and the Tropical Ocean Global Atmosphere (TOGA)

program.

JAPAN

The Japanese are engaged in an active remote

sensing satellite program and are expected to expand

their work in this arena, both in ground and space

segments.24 Movements into the commercial sales of

remote sensing data seem likely, as Japan moves into

a continuity of data flow from their own Earth

Resources Satellite (JERS-1) and the Advanced Earth

Observing Satellite (ADEOS).

The Geostationary Meteorological Satellite (GMS)

GMS “Himawari” series satellites have contributed

to the improvement of Japan’s meteorological services

and development of weather satellite technology .25

Data gathered by the GMS satellites are shared with the

World Weather Watch, Operational weather data,

including monitoring of cloud cover, temperature

profiles, real-time storm monitoring, and severe storm

warning, are key missions objectives of the GMS

series. The cloud distribution pictures are used in

countries of Southeast Asia and the Western Pacific.

The first satellite in the GMS series was launched by

a U.S. Delta rocket in July 1977, with later GMS

satellites boosted by Japan’s own N-II and H-1 rockets.

GMS-2 and the GMS-3 were launched in August 1981

and August 1984, respectively, with the H-1 launching

the GMS-4 in September 1989. Now under development for a projected 1994 launch is the GMS-5, which

is expected to conclude the series.

Japan’s space agency, NASDA, developed the first

two GMS satellites and the Japan Meteorological

.22 peter B. de%lding, “Potential Partners Give Helios Follow-On Cool Response,’ Space News, June 28, p. 5.

23 R, Hal], f ‘TOpE~oseldon satellite: Emb]ing a Joint U, S. French ~ssion for G]ob~ Ocem s~dy, ’ presented at QIst congress Of the

International Astromutical Federation, (IAF-9O-1O1), Dresden, Germany, Oct. 6-12, 1990.

~ NAL7DA-Nah~na[ Space Development Agency of Japan, Tokyo, Japan, 1991.

M Geo~faTionan Mereoro/()<qlcu/ ,$afe//ite-5, National Space Development Agency of Japan, 3/10~ Tok>ro, JaPan> 1991.
176 I Remote Sensing From Space

Agency was in charge of the installation of ground

facilities needed for their operations. Since GMS-3, the

two agencies share the development costs of the

satellite. NASDA is responsible for development

efforts, while the Japan Meteorological Agency manages the operation of the satellites and the distribution

of data.

Design of the GMS, which is manufactured by

Hughes Communications and Space Group and Japan’s

NEC, draws heavily from the Hughes-built U.S. GOES

meteorological satellite. The GMS satellites are spinstabilized, and carry radiometers, the space environment monitor, along with a data collection system,

which gathers environmental data from ground-based

instruments. The GMS-3 was replaced by the GMS-4

as the primary GMS satellite, but is still capable of

transmitting cloud photos over the earth 28 times per

day. GMS-4 provides 1.25-km resolution in the visible

channel, and 5-km resolution in the infrared charnel.

Sensors onboard the GMS-4 include a single imaging

Visible and Infrared Spin Scan Radiometer (VISSR)

operating in 0.5 to 0.75 microns visible band and 10.5

to 12.5 microns in the infrared band. This instrument

provides a full-disc Earth image in less than a half

hour, simultaneously in both visible and infrared

bands. The visible channel consists of four detectors

(with four backup detectors) that scan simultaneously,

covering a 1.1-km area. The GMS-4 also carries a

space environment monitor to survey radiation levels

at geostationary altitude and to monitor solar protons,

electrons, and alpha particles.

GMS-5 will be launched in late 1994, and will be

similar to the GMS-4 design. It will carry a Search and

Rescue experiment on behalf of the Ministry of

Transport of Japan.

Marine Observation Satellite (MOS-1, MOS-1b)

The MOS-1 is Japan’s first domestically developed

Earth observation satellite.2b MOS-1 was launched in

February 1987 from Tanegashima Space Center by an

N-II rocket. Its successor, MOS-lb, was launched by

a H-I rocket in February 1990. These spacecraft were

sent into a sun-synchronous orbit of approximately

909 km and have a 17-day recurrent period, circling the

Earth 14 times a day. The two spacecraft can be

operated in a simultaneous and/or independent mode.

MOS-1 and MOS-lb (also called MOMO-1 and

MOMO-lb) are dedicated to the following mission

objectives:

●

●

●

Establishment of fundamental technology for

Earth observation satellites;

Experimental observation of the Earth, in particular the oceans, such as water turbidity of coastal

areas, red tide, ice distribution; development of

observation sensors; verification of their functions and performance;

Basic experiments using the MOS data collection

system.

Each of the spacecraft carries three sensors: a

Multispectrum Electronic Self-Scanning Radiometer;

a Visible and Thermal Infrared Radiometer and a

Microwave Scanning Radiometer (table D-l). Both

satellites are designed for a two-year lifetime.

Facilities to receive data directly from the MOS

series are located at Japan’s Earth Observation Center

in Hatoyama-cho, Hiki-gun, Saitama prefecture. Data

processing facilities have also been set up by NASDA

at the Remote Sensing Center of the National Research

Council of Thailand, located in a suburb of Bangkok.

This Thailand station can receive MOS data over

Thailand, Bangladesh, Bhutan, Cambodia, Malaysia,

Vietnam; and part of China, India, Indonesia, Nepal

and Philippines. The Thailand collection center transports monthly data to Japan’s Earth Observation

Center and NASDA for processing and generation of

products.

MOS products are available for a fee from the

Remote Sensing Technology Center of Japan

(RESTEC). RESTEC was established under the guidance of the Science and Technology Agency and

NASDA in 1975 as a foundation, with the assistance

of Mitsui & Co., Ltd. and the Mitsubishi Corporation.

Earth Resources Satellite-1 (JERS-1)

JERS-1 is a joint project of the Science and

Technology Agency, NASDA, and the Ministry of

International Trade and Industry (MITI). JERS-1 was

26 Marine Observation Satellite-i, National Space Development Agency of Japaq 8/5T, Tokyo, Japa& 1990. Keiji Maruo, “Remote Sensing

Activities in Japan, ’ in Space Commercialization: Satellite Technology, edited by F. Shahrokhi, N. Jasenhdiyana, and N. Tarabzouni, vol. 128

of Progess in A.womzutics and Aeronuufic.r, American Institute of Aeronautics and Astronautics, Washingto& DC, 1990.

~T Earth Resources Sareflire-1, National Space Development Agency of Japa~ 3/10’r, To@o, Japan, 1991.
Appendix D—Non-U.S. Earth Observation Satellite Programs I 177

launched by an H-I rocket in February 1992, 27

Problems with a balky radar antenna were overcome in

the early months of the mission.

The JERS-1 is Japan’s third domestic remote

sensing satellite (following the MOS-1 and MOS-lb)

and will observe Earth using optical sensors and an

L-band SAR for two years. JERS-1 will enable the

overlaying of optical multispectral data with allweather radar imagery. JERS-1 was placed in a

sun-synchronous orbit of approximately 570 km. Its

recurrent period over the same location is 44 days.

The primary purpose of JERS-1 is to verify functions and performance of optical sensors and a

synthetic aperture radar, and to establish an integrated

system for observing the Earths resources. Earth

observations are to focus on land use, agriculture,

forestry, fishery, environmental preservation, disaster

prevention, and coastal zone monitoring.

The JERS-1 radar system has day/night and allweather observation capabilities. Resolution of the

radar is 18 meters with a swath width of 75 km. The

SAR is capable of an off-nadir angle of 35 degrees

(table D-l), An onboard recorder records SAR and

OPS data when no data receiving station is available,

allowing JERS-1 to attain global coverage.

In Japan, JERS-1 data are received at NASDA’S

Earth Observation Center, Saitama. In addition, .JERS -

1 data are received at the Tokai University in

Kumamoto Prefecture, the Showa Base in the Antarctic, and the Thailand MOS-1 station. Under a NASDANASA Memorandum of Understanding, the NASAfunded SAR station in Fairbanks, Alaska, also receives

JERS-1 data. These data overlap the SAR data from the

already-orbiting European ERS-1 mission and the

Canadian Radarsat mission, planned for launch in

1994.

Advanced Earth Observation Satellite (ADEOS)

The main objective of ADEOS, the next generation

of Japanese Earth observation satellites, is to continue

and further advance Earth observation technology

spurred by the MOS-1 and JERS-1 programs. The

spacecraft is to have a 3-year lifetime.28 ADEOS will

have a sun-synchronous, 98.6 degree inclination orbit

with a crossing time of 10:30 am, and a repeat cycle of

41 days.

ADEOS will verify functions and performance of

two NASDA sensors, the Ocean Color and Temperature Scanner (OCTS) and the Advanced Visible and

Near Infrared Radiometer (AVNIR). The OCTS will

be used for marine observation with high precision,

and the AVNIR for land and coastal observation with

high resolution.29

NASA plans to fly the Total Ozone Mapping

Spectrometer (TOMS) aboard ADEOS, as well as a

NASA Scatterometer (NSCAT), which will provide

accurate measurements of ocean surface winds. Such

a device was demonstrated during the U.S. Seasat

program in 1978.

Along with the U, S.-provided sensors, the Interferometric Monitor for Greenhouse Gases (IMG) will be

provided by the Ministry of International Trade and

Industry of Japan, the Improved Limb Atmospheric

Spectrometer and the Retroreflector in Space will be

provided by the Environment Agency of Japan. Lastly,

the Polarization and Directionality of the Earth’s

Reflectance (POLDER) instrument is to be provided

by the French space agency, CNES,

The ADEOS program will also conduct experiments

on Earth observation data relay using the Engineering

Test Satellite-VI and the Experimental Data Relay and

Tracking Satellite to enhance global observation

capabilities. Lastly, Japanese officials expect to demonstrate the ADEOS modular design they believe

necessary to build future Japanese polar-orbiting

platforms.

ADEOS was initially to be launched by the H-II

rocket in early 1995, but delays in the H-II program

and problems integrating non-Japanese instruments

have caused a slip in schedule. Japan now plans a

February 1996 launch.

The OCTS instrument planned for ADEOS is to be

a multispectral radiometer designed to measure global

ocean color and sea surface temperature simultaneously during the day. It is based on the VTIR

instrument flown on the MOS-1 series. OCTS spatial

resolution will be approximately 700 meters, with a

1,400-krn swath width. The OCTS will be pointable on

x (~EO,S) Adl,anced Earth Obsenl;ng Satellite, National Space Development Agency of JaP~ 3/1 ~t TOkYO! ~aP~t 191 ~

29 N, IWWM, Makoto Kajii et al., ‘ ‘Status of ADEOS Mission Sensors, ’ presentd at 42d Congress of the International Astronautical

Federation (IAF-91-144), Montreal, Canada, Oct. 5-11, 1991.
178 I Remote Sensing From Space

command and capable of tilting along track to either

side of nadir.

The AVNIR is a high spatial resolution multispectral radiometer for Earth observing during the day in

visible and near-infrared regions. AVNIR is a thirdgeneration sensor using CCD technology, preceded by

MESSER of the MOS-1 and OPS of the JERS-1. The

sensor swath width is approximately 80 km. AVNIR is

equipped with a pointing mechanism that selects the

observing path arbitrarily in the cross track direction of

ADEOS flight.

Major specifications of the sensors aboard ADEOS

are as follows:

●

●

●

●

●

The NASA Scatterometer (NSCAT) can measure

surface wind speed and direction over the global

oceans. Swath width: 1,200 km; frequency:

13.995 GHz; wind speed measurement accuracy:

2 m/s.; direction accuracy of 20 degrees (at spatial

resolution of 50 km). This sensor will observe

globally, day and night;

The NASA Total Ozone Mapping Spectrometer

(TOMS) will observe ozone changes, evaluate

changes in ultraviolet radiation and sense sulfur

dioxide in the atmosphere. Swath width: 2,795

km; wavelengths: 304.0, 312.5, 325.0, 317.5,

332.6 and 360 microns. This sensor will operate

in the day on a global basis;

The CNES Polarization and Directionality of the

Earth’s Reflectance (POLDER) sensor will observe solar radiation reflected by the Earth’s

atmosphere. Swath width: 1,440 X 1,920 km;

wavelengths: 0.443, 0.490, 0.520, 0.565, 0.670,

0.765, 0.880, 0.950 microns. This device will

operate in the day on a global basis;

MITT’s Interferometric Monitor for Greenhouse

Gases (IMG) will observe carbon dioxide and

other greenhouse gases. Swath width: 20 km;

wavelengths: 3.3-14 microns. This sensor will

observe globally, day and night;

Environment Agency of Japan’s Improved Limb

Atmospheric Spectrometer (ILAS) will observe

the micro-ingredients in the atmosphere over

high-latitude areas on the Earth’s limb. Wave-

●

lengths: 0.75-0.78 and 6.2-11.8 microns. This

sensor will operate on a regional basis;

Environment Agency of Japan’s Retroreflector in

Space (RIS) that measures ozone, fluorocarbons,

carbon dioxide, etc., by laser beam absorption.

Laser beam is transmitted from ground station

and reflected on ADEOS. Wavelengths: 0.3-14

microns. This experiment will be done on a

regional basis.

Mission operation of ADEOS will be controlled

from the NASDA Earth Observation Center (EOC).

However, the limited visibility of ADEOS by the EOC

will require use of foreign, near-polar ground stations

as well, Data rate for direct transmission from ADEOS

is a maximum of 100 megabits per second (Mbps).

Future Planning

Future plans by Japan in Earth observation satellites

center on a number of post-ADEOS sensors and

satellites, as well as enhancement of the remote

sensing ground segment, data networks, remote sensing training activities, and marketing.30

Tropical Rainfall Measurement Mission (TRMM)-

TRMM is detailed in appendix A.

Japanese Polar Orbiting Platform (JPOP)--

Japanese officials expect this platform to succeed

ADEOS in the late 1990s and to constitute a Japanese

contribution to the international Earth observation

system. The JPOP is expected to be launched by H-II

rocket into Sun-synchronous orbit after 1998.

Ground Facilities—Use of NASDA’S Earth Observation Center (EOC) will increase given its role in the

data reception and processing of Landsat, SPOT,

MOS-1, MOS-lb, JERS-1 and ADEOS data.

Data Distribution

The role of the Remote Sensing Technology Center

of Japan (RESTEC) will likely grow in future years.31

RESTEC handles data distribution for Landsat, MOS,

and SPOT to general users in Japan and foreign

customers. NASDA data policy for MOS-1 is to charge

for the cost of reproduction and handling. NASDA is

responsible for processing JERS-1 data, but RESTEC

m Monitom’ng the Ea~h Envirowntfiom space: A Scenario of Earth Observation for the Next Decade, National Space Development

Agency of Japan (NASDA), Tokyo, Japan.

31 RESTEC: Remote Sensing Technology Center of Japan, To&o, Jap~ 1991.
Appendix D—Non-US. Earth Observation Satellite Programs I 179

will distribute the NASDA-processed JERS-1 data to

Japanese and foreign users.

Japanese geography and politics permit only one

satellite tracking and receiving facility, which does not

view Earth-orbiting spacecraft often enough to permit

global data acquisition and relay to Earth of tape

recorded data. Until Japan establishes a data relay

satellite capability, it must rely on international

cooperation to obtain data from its satellites.32

COMMONWEALTH OF INDEPENDENT

STATES (CIS)

The former Soviet Union’s space activities show a

great and expanding interest in Earth observation, not

only for military purposes, but for assessing resources

on a regional and global scale.33

Beyond military spaceborne reconnaissance assets,

the Soviet meteorological and remote sensing programs have been forged into an integrated network,

comprising various spacecraft. Today the CIS operates

eight different types of space platforms-both piloted

and automated spacecraft-that provide global environmental data, and it is proposing even more systems

for the future.34 This network is comprised of Meteor

2 and Meteor 3-series satellites; the Okean-O spacecraft; the Resurs-0, Resurs-Fl and Resurs-F2 satellites; and the piloted Mir space station complex.

Soviet authorities have claimed that their nation’s

meteorological and remote sensing satellites provide

an economic savings of some one billion rubles each

year. Indeed, Earth observation data are widely used in

the former Soviet Union for land and forestry management, mapping soil erosion threats, studying ice

situations in polar areas, and monitoring earthquake

and avalanche hazards.35

Meteor

Meteor was the first civil applications satellite

deployed by the former USSR. It is comparable, in

many ways, to the U.S. NOAA series. Following a

long stretch of testing under the Cosmos satellite label,

the first Meteor was identified as such in 1969.

Numbers of Meteor l-class spacecraft were launched

and then replaced (after 1975) by the current Meteor

2-class spacecraft and (after 1985), by the Meteor 3

satellite. Meteor 2 and Meteor 3 satellites are routinely

launched, typically twice a year.

Meteor 2 satellites are placed in 950-km polar orbits,

with two or three of this class of spacecraft in operation

at all times. Grouped in a constellation, individual

Meteor 2 satellites gather data from one-fifth of the

globe during a single circuit of Earth, relaying data on

clouds, ice cover, and atmospheric radiation levels.

Two of these satellites provide 80 percent coverage of

the Earth’s surface in six hours.

Onboard a Meteor 2 satellite are scanning radiometers for direct imaging and global coverage; a scanning

infrared radiometer for global coverage; and a scanning infrared spectrometer, covering eight channels

(table D-l). Automatic Picture Transmission (APT) is

carried out from a Meteor 2-class satellite at frequencies between 137 and 138 Mhz, therefore compatible

with international APT formats. Some 15,000 APT

terminals exist across the CIS territories.

The newer Meteor 3-class satellites are being placed

into higher orbits, 1,200 km, in order to prevent

coverage gaps in the equatorial regions. Payload of

Meteor 3 spacecraft are similar to Meteor 2 satellites

(table D-l). Also onboard Meteor 3-class spacecraft is

a radiation measurement device to record electron and

proton charges in the space environment.

The Meteor 3 satellites are designed to accommodate additional payload packages. For example, the

August 1991 Meteor 3 launch carried NASA’s Total

Ozone Mapping Spectrometer (TOMS).3G Russia plans

to fly Earth radiation budget instruments provided by

CNES aboard a future Meteor 3.

Russian authorities have discussed developing a

Geostationary Operational Meteorological Satellite

32 S& S&fer, op. cit. footnote 6.

J3 Nicbolas L. Johnso~ The soviet Year in Space 1990, Teledyne Brown Engineering, Colorado Spfigs, CO, 1991.

~ Neville Kidger, “The Soviet Unmanned Space FleeL” Spacejl’ight, vol. 32, July 1990, pp. 236-239.

N MMcla Smlm ,Sol,ief Space Comrcia/lzafion Ac~~,i~es, CRS Repo~ for Conwess, congr~sioti Reseuh Service, 88-473 SPR,

Washington DC, July 6, 1988. Kazakov, Roudolf V. Applications of Soviet Remote Sensing Data for Studies of Natural Resources and

Mapping Pu~oses. Sojuzkarta Company, Moscow, 1991.

36 Brim Dunbar and Dolores Beasley, NASA News, “Soviets to Launch NASA Instrument to Study Ozone Levels,’ Release 91-127, NASA

Headquarters, Washington, DC, Aug. 12, 1991; NASA Meteor-31TOMS Press Kit, NASA Headquarters, Washingto& DC, Aug. 12, 1991.
180 I Remote Sensing From Space

(GOMS) that would carry a sensor suite similar to the

NOAA GOES-Next satellite series. Economic turmoil

in Russia has delayed GOMS deployment. GOMS

would acquire, in real time, television images of the

Earth’s surface and cloud cover in the visible (0.4-0.7

microns) and infrared (10.5 -12.5 microns ) regions of

the spectrum, providing resolutions of 1-2 km and 5-8

km, respectively, with a total field of view of 13,500

km x 13,500 km.

Okean-O

Toward the end of the 1980s, the former Soviet

Union developed the Resurs system of remote sensing

satellites, of which Okean-O is a part. Okean-O is a

series of all-weather oceanographic satellites with real

aperture side-looking radars. These satellites are built

to provide all-weather monitoring of ice conditions;

wind-induced seaway, storms and cyclones; flood

regions; and ocean surface phenomena.

A standard Okean-O is placed in a 630- to 660-krn

orbit. The spacecraft carries a side-looking radar, a

microwave scanning radiometer, a medium-resolution

multispectral (4-channel) scanner and a highresolution multispectral (2-channel) scanner.

Okean satellites make use of the APT frequency of

137.4 Mhz. A data collection and distribution system

called Condor allows data to be culled by Okean

spacecraft from ground-based instruments, then relayed to ground stations. These data can then be

relayed directly to ships at sea via communications

satellites.

A follow-on to Okean-O has been discussed for

launch in 1993. Significant changes include addition

of a second side-looking radar. The modified Okean

would then provide coverage on both sides of the

satellite’s flight path, sweeping out a wider swath, but

retaining the same resolution. In addition, a more

advanced multispectral scanner will make use of three

visible bands with a resolution of 200 meters and three

infrared bands yielding a 600-meter resolution.

Resurs-O

The Resurs-O spacecraft are roughly comparable to

the U.S. Landsat system. These digital Earth resources

satellites, derived from the Meteor series, circle Earth

at altitudes of 600 km to 650 km in sun-synchronous

orbit. They carry a multiple multispectral instrument

package, operating in the visible to thermal infrared,

and have been touted for their ability to detect

industrial pollution.37 Remote sensing hardware aboard

Resurs-O comprise two high-resolution, multiband

(3-channel)CCD scanners, a medium-resolution multiband (5-channel) conical seamer, a multiband (4-

channel) microwave radiometer, and a side-looking

synthetic aperture radar. The Resurs-O spacecraft can

process some data in orbit and relay realtime data at

7.68 mbps.

Russians officials plan a follow-on to this series

carrying high-resolution optical sensors capable of 15-

to 20-meter resolution. Discussions have also been

held about establishing commercial Resurs-O receiving stations in Sweden, as well as the United Kingdom.

Resurs-F

This class satellite mimics CIS military reconnaissance spacecraft by using a capsule containing exposed

film that is ejected by the spacecraft and returned to

Earth under parachute. 38 Resurs-F1 and Resurs-F2

spacecraft use the Vostok reentry sphere, used previously to launch the frost cosmonauts into orbit.

The Resurs-Fl typically flies at 250 km to 400 km

altitude for a two-week period and carries a threechannel multispectral system which includes three

KATE-200 cameras and two KFA-1OOO cameras. The

KATE-200 camera provides three spectral bands for

Earth observing (table D-1) at a swath width of 180

km. Stereoscopic imagery can be accomplished with

an overlap of 20, 60, or 80 percent. Resolution varies,

according to spectral band and survey altitude, from 10

to 30 meters. The KFA-1OOO cameras provide 300 X

300 mm frame window size with images capable of

being taken in stereo, with an overlap of 60 percent.

The Resurs-F2 spacecraft normally cover Earth in 3-

to 4-week periods (sometimes as long as 45 days) in a

variable orbit of 259 km to 277 km. Onboard is the

MK-4 camera system which can survey the Earth using

a set of four cameras, Six spectral channels from 0.635

to 0.700 are available. Imagery provided by Resurs-Fl

37 Resours.O.Space System for Ecological Monitoring, The Soviet Association for the Earth Remote Sensing, MOSCOW, December 1990.

38$ *USSR: @bi~ ~terials ~ocessing’ ~SO details Earth resources photographic return capsules. Science and TedVdOgy perspech”ves,

Foreign Broadcast Information Service, vol. 5, No. 6, June 29, 1990, pp. 5-7.
Appendix D-Non-US. Earth Observation Satellite Programs I 181

and F2 spacecraft are being offered commercially

through the Soyuzkarta company .39

Almaz

Recently, the CIS collected a wealth of data from its

A1maz satellite. Almaz-1 was a large spacecraft

equipped with synthetic aperture radar (SAR) for

day/night operations. Launched in March 1991 and

operated until October 1992, the Almaz followed a

300-krn-high orbit, and provided coverage of an

appointed region at intervals of one to three days. Its

orbital position was corrected every 18-31 days, and

accounted for considerable fuel use. The orbit was also

changed frequently to comply with customers’ requests. A similar bus-sized, radar-equipped prototype

spacecraft-Cosmos-l 870-was launched in 1987,

and was based upon that of the piloted Salyut and Mir

40 Cosmos- 1870 operated for two years, space stations.

producing radar imagery of 25 to 30 meters resolution.

An Almaz Corporation was formed to stimulate

commercial use of the satellite data. G1avkosmos, the

civil space arm in Russia, NPO Machinostroyenia, and

the U.S.-based Space Commerce Corporation of Houston, Texas, established a joint Data Processing and

Customer Support Center in Moscow to assist customers in using Almaz data. The French company, SPOT

Image, also markets Almaz data in the United States

and Canada. In 1992, Hughes STX Corp. of Lanham,

Maryland, signed an agreement with Almaz Corp. of

Houston to be exclusive worldwide commercial marketer, distributor, processor and licenser of data from

the Almaz-l spacecraft.

41 According to some reports,

Almaz data sales have been slow; a sales target of $2

million for 1992 may have been unrealistic.42

The Russians would like to launch and operate an

Almaz-2. However, lack of capital and a weak market

for Almaz data have prevented such arrangements.

Mir

Since the first crew occupied the Mir space station

in 1986, cosmonauts onboard the orbiting complex

have completed numerous experiments dedicated to

Earth remote sensing. Various Earth imaging systems

have been flown to the Mir, such as the Kate-200,

KFA-1OOO, and the MK4 camera hardware also used

on board the Resurs-1 and Resurs-2 satellites.

The Kavant-2 module, attached to the central core of

the Mir in December 1989, carried the MKF-6M

camera, capable of imaging Earth at a resolution of

22.5 m.

Of significance is the potential for further expansion

of the Mir complex to include a Priroda remote-sensing

module, which has been under development for several

years. Russia plans to attach the Priroda module to Mir

in late 1994. Use of instruments carried inside the

module would be geared to monitoring ocean surface

temperatures, ice cover, wind speed at the ocean

surface, and surveying concentrations of aerosols and

gases in the atmosphere.

INDIA

India has invested heavily in space-based remote

sensing. The Indian Space Research Organization

(ISRO) is the primary government space agency for the

country, organized under the government’s Department of Space. The ISRO Satellite Centre is the

primary laboratory for design, building, and testing of

Indian satellites.

A National Remote Sensing Agency was established in 1975 and is charged with shaping an

operational remote sensing system for India. Since

1979, India’s central Earth station in Shadnagar has

received U.S. NOAA spacecraft data, as well as

information transmitted by Landsat, SPOT, and the

country’s own Indian Remote Sensing (IRS) spacecraft. IRS is the data mainstay for India, accounting for

over 72 percent of the data requests by users, followed

by Landsat at 18 percent and SPOT around 6 percent .43

India’s remote sensing program centers on use of the

Indian Satellite (INSAT) series, two Bhaskara spacecraft, the Rohini satellites, and the Indian Remote

w soyuz~rta, Foreign Trade Assoia[io~ Kartex, MOSCOW . Sovero No. 28 1/88.

.@ BuYer*~ Guide Almz Radar Remote Sensing ,yalP//ite, Space Commerce Corporation, Houston. Texas; William B Wirin! ‘‘New Vision

from Space: ALMAZ, ” Aerospace & Defense Science, October/November 1990, pp. 19-22, William B. Wirim Almaz: hoking Through

Clouds, presented at 1 lth Symposium EARSel, Gru, Austria July 3-5, 1991.

q] “Hughes STX Signs Agreement on Data from Russian Satellite, ” The Wo.rhz’ngton Post, Mar. 2, 1992, p. 7.

42 Daniel J. Marcus, ‘‘Ahnaz Team Fears Shutdown Without More Foreign Sales,’ Space News, vol. 3, No. 3, Jan. 27-Feb, 2, 1992, p. 23.

A? [nV,entorY of Remote ,~en$lng Faclll[ie$ and ~tiv,itie$ in the E,~CAp Region, United Nations Inventory Report: India, December 1990.
182 I Remote Sensing From Space

Sensing satellite series: IRS-1A and IRS-lB, Along

with the development of these spacecraft, India has

pursued an independent launch capability, although

U. S., Soviet, and European boosters have also been

utilized to launch Indian satellites.

Bhaskara

The Bhaskara series served as experimental spacecraft, launched by Soviet boosters in 1979 and 1981.

The Bhaskara spacecraft were each placed in a roughly

400-mile-high Earth orbit. Both satellites carried slow

scan vidicon equipment and passive microwave radiometers. The satellite’s vidicon equipment operated in

0.54-0.66 micron and 0.75-0.85 micron spectral channels, and produced images for land use, snow cover,

coastal processes, and for forestry purposes. The

radiometers operated in the 19, 22, and 31 GHz range

and collected data on sea surface phenomena, water

vapor and liquid water content.

Rohini

The Rohini series began with Rohini-1 launched

into Earth orbit in July 1980, using India’s national

booster, the SLV-3, While the initial Rohini was

apparently used to measure rocket performance, Rohini2, orbited in May 1981, carried remote sensing

equipment but operated for only 9 days. Rohini-3 was

orbited in April 1983 and also carried equipment for

“remote sensing’ purposes. Material provided by

ISRO for this assessment contains no mention of the

Rohini series. Western officials have claimed these

satellites are designed to assist in the creation of an

Indian military reconnaissance capability.

INSAT

The Indian National Satellite system combines both

Earth observation and domestic communications functions. The INSAT spacecraft built to date have been of

American design, purchased by India from Ford

Aerospace. The INSAT-lA was launched in April

1982 by a U.S. Delta rocket, but suffered problems

during deployment of spacecraft hardware. An INSAT

1B was subsequently launched using a U.S. Space

Shuttle in August 1983. INSAT 1C was launched by

an Ariane booster in July 1988, and an INSAT ID was

rocketed into orbit by a commercial U.S. Delta in June

1990.

INSAT remote sensing activities center on using a

two-channel Very High Resolution Radiometer (VHRR)

that yields 0.55-0.75 micron visible and 10.5-12.5

micron infrared images of the Earth. From their

geostationary altitude, INSAT spacecraft produce

imagery every 30 minutes. INSAT-series spacecraft

have a design life of some ten years. In addition to

imagery, the INSAT satellites relay data collected from

some 100 hydrological, oceanographic, and meteorological ground stations.

INSAT-2 is under development, and will be constructed by ISRO and Indian companies and launched

by an Ariane booster. Similar in capabilities to

previous INSATS, the INSAT-2 is expected to yield

higher VHRR resolution in the 2 km visible and 8 krn

infrared. A series of two INSAT-2 test spacecraft and

three additional operational satellites is now being

planned.

Indian Remote Sensing Satellite (IRS)

As India’s first domestic dedicated Earth resources

satellite program, the IRS series provides continuous

coverage of the country, with an indigenous ground

system network handling data reception, data processing and data dissemination. India’s National Natural

Resources Management System uses IRS data for

many projects.

To date, two IRS satellites have been launched:

IRS-1A in March 1988 by a Russian launcher; and

IRS-l B in August 1991, also launched by a Russian

booster, Both IRS spacecraft carry identical onboard

hardware.

IRS-1A and IRS-lB are the backbone of India’s

Natural Resources Management System; both are in

904-km polar sun-synchronous orbit. Each carries two

payloads employing Linear Imaging Self-scanning

Sensors (LISS), which operate in a pushbroom scanning mode using CCD linear arrays. The IRS satellites

have a 22-day repeat cycle. The LISS-I imaging sensor

system constitutes a camera operating in four spectral

bands compatible with the output from Landsat-series

Thematic Mapper and SPOT HRV instruments (table

D-l), Geometric resolution of the LISS-I is 72 meters

at a swath of 148 km. The LISS-IIA and B are

comprised of two cameras operating in 0.45 to 0.86

microns with a ground resolution of 36.5 meters, each

with a swath of 74 km. The two units are located on

either side of the LISS-I and view either side of the

ground track with a 3-km lateral overlap.
Appendix D—Non-U.S. Earth Observation Satellite Programs I 183

Data products from the IRS can be transmitted in

real time, or by way of tape recorder. As part of the

National Remote Sensing Agency’s international services, IRS data are available to all countries which are

within the coverage zone of the Indian ground station

located at Hyderabad: Afghanistan, Bahrain, Bangladesh, Bhutan, Burma, Cambodia, China, Indonesia,

Iran, Laos, Malaysia, Maldives, Mali, Nepal, Oman,

Pakistan, Qatar, Saudi Arabia, Singapore, Socotra,

Somalia, Sri Lanka, Thailand, United Arab Emirates,

the CIS (former USSR), Vietnam, and Yemen. These

countries can receive the raw/processed data directly

from the NRSA Data Center.

IRS Follow-on Series

Second-generation IRS-l C and 1D satellites are

being designed to incorporate sensors with resolutions

of about 20 meters in multispectral bands and better

than 10 meters in the panchromatic band apart from

stereo viewing, revisit and onboard data recording

capabilities. ISRO is planning to add a band in Short

Wave IR (SWIR) at a spatial resolution of 70 meters.

In addition, a Wide Field Sensor (WiFS) with 180

meters spatial resolution and a larger swath of about

770 km is planned for monitoring vegetation.

India expects to launch IRS-l C sometime in 1994,

while IRS-l D will be launched in 1995 or 1996. An

IRS-series spacecraft capable of microwave remote

sensing—similar to Europe’s ERS-1—is also under

consideration for launching in the late ‘90s.

Ground Facilities

IRS data are regularly acquired at the National

Remote Sensing Agency (NRSA) Earth station at

Shadnagar, Hyderabad. Five regional remote sensing

service centers have been established to provide users

digital analysis and interpretation of IRS data and other

remotely sensed satellite information. The centers are

located at Bangalore, Dehra Dun, Jodhpur, Nagpur and

Kharagpur. Also, state remote sensing centers in all 21

states have been established to carry out projects of

direct relevance to the states and/or participate in

national programs.

The use of low-cost PC-based digital image processing systems have permitted widespread applications of

remote sensing data throughout India. IRS data have

been used to monitor drought, map saline/alkaline

soils, estimate large area crop production, and inventory urban sprawl of all cities with populations greater

than one million.

CHINA

China’s remote sensing activities have been tied to

satellite communications and geographic information

systems designed to alert the government of environmental situations, such as impending flood conditions

Capable of launch- and to estimate disaster damage.44

ing its own satellites with its Long March boosters,

China’s remote sensing work centers around the Feng

Yun (FY) satellite series to gather meteorological

data, 45 while China’s FSW (see below) recoverable

satellites have returned film of remotely sensed scenes

to Earth-useful for commercial and military purposes.

46 In December 1986, the Chinese inaugurated

operational use of a Landsat receiving station, purchased from the United States. China pays a $600,000

annual access fee to EOSAT to use the Landsat ground

terminal. 47 China can market the data without restriction. The station is positioned at Miyun, northeast of

Beijing, with processing facilities situated northwest

of Beijing. Lastly, China and Brazil are cooperating on

the Earth Resources Satellite system comprised of two

spacecraft and several Earth stations.

Feng Yun (FY)

The Feng Yun (FY) “Wind and Cloud” satellites

are built for meteorological purposes, to monitor

conditions of China’s vast territory and coastline, Two

of the FY series have been launched since September

1988.

While China can obtain realtime cloud NOAA/TIROSN data, this information is not in the three-dimensional

“The Proposat About Constructing the National Disaster Monitoring, Forecast and Control a c. FaW-~ Tong I@, and Yang Jia-c~,

System, ” presented at 42d Congress of the International Astronautical Federation, (T.AF-91-1 13), Montreal, Canada, Oct. 5-11, 1991.

45 M. ~fiong, and XuFuxia%, “Chinese Meteorological Satellites and Technical Experiment of the Satellites,” presented at 42d Congress

of the International Astronautical Federation (1.AF-91-017), Montreal, Canadq Oct. 5-11, 1991.

46 Recoverable Sare//lf@,$W~icorgra},iO Test P/a&orm, Chinese ~demy of Space Technology, Beijing, Chim.

47 ~c~ Smlti, space Comercia/jzanon in china a~~apan, CRS Repofi for Congress, (88-519 SPR), Congressional Research Service,

Washin@oU DC, July 28, 1988, pp. 8-9.
184 I Remote Sensing From Space

format needed for medium and long-range weather

forecasting, numerical forecasting, and climate research. Similarly, China has access to data from the

Japanese geostationary meteorological satellite but

this satellite is positioned to the east of China,

seriously distorting cloud imagery of the vast western

part of China. Therefore, beginning in the 1970s,

China started its own polar-orbiting meteorological

satellite program, followed in the mid-1980s with

plans to develop a geostationary meteorological satellite.

The FY-1 had a one-year design lifetime, but failed

after 39 days. During its life, China’s first experimental

weather satellite relayed high-quality imagery to Earth.

While four visible channels from the satellite broadcast

successfully, signals from the infrared charnel were

poor, apparently as a result of contamination of the

infrared sensing hardware at the launch site. An

attitude control failure shortened the mission of the

satellite.

The FY-1 made 14 cycles per day (seven passes per

day over Chinese territory) in a near polar sunsynchronous orbit with an altitude of 900 km. Part of

its instrument package contained two scanning fivechannel Advanced Very High Resolution Radiometers

(AVHRRS), four in the visible spectrum and one in

infrared (table D-1 ). Day and night cloud images were

acquired, permitting measurements of sea surface state

and silt and chlorophyll concentrations in brine.

Use of C band frequency permitted the FY-1 to

incorporate a High Resolution Picture Transmission

system in a data format the same as that of the

NOAA/TIROS-N and with a ground resolution of 1.1

km. Also, an APT transmitter sent realtime cloud

images with a resolution of 4 km.

Hardware changes were made in the design of

FY-l B, orbited in September 1990. Further refinement

of the FY-1 class satellite, according to some sources,

suggest China may launch an FY-l C and FY-lD

satellite, then embody that technical expertise into a

fully modified FY-1 satellite.

At present, the development of FY-2A is underway,

with a launch set for the mid-1990s. This satellite will

be placed in geostationary orbit over China and is to

provide almost instantaneous weather/climate data

collection over every region of China and Asia, as well

as most parts of Oceania.

Fanhui Shi Weixing (FSW) Recoverable Satellite

The Chinese FSW commercial platform series is

capable of carrying various kinds of equipment into

orbit, including remote sensing hardware. Presently,

an FSW-I and larger FSW-II platform are being made

available by the Chinese Academy of Space Technology. These are geared primarily for microgravity

research purposes. The FSW-I recoverable satellite can

remain in orbit for 5 to 8 days and is replete with

telemetry for realtime data transmission, or tape

recorders for data storage. Recoverable payloads of 20

kg are possible. For the FSW-II, recoverable payload

weight of 150 kg is possible, with the satellite able to

remain in orbit for 10 to 15 days. The price for use of

an FSW recoverable satellite has been reported to be

$30,000 to $50,000 per kilogram.

The FSW is similar to the satellite recovery concept

used in the U.S. Air Force Discovery program of the

late 1950s and early 1960s. Previous FSW returnable

capsules have reportedly been used for capturing

high-quality imagery for military reconnaissance purposes.

China-Brazil Earth Resources Satellite (CBERS)

Initiated by an agreement signed July 6, 1988, China

and Brazil have jointly pursued a cooperative project

to build two remote sensing satellites, each capable of

SPOT-like performance using linear CCDS.

48 The

CBERS-1 and CBERS-2 would be designed by the

Xian Research Institute of Radio Technology, which

would also supply the imaging system. Brazil’s

Institute of Space Research (INPE), near Sao Paulo,

would be responsible for satellite structure, power

supply, data collection system and other items.

China would take on the larger financial stake for the

CBERS satellites-70 percent to Brazil’s 30 percent.

In U.S. dollars this percentage split represents an

investment of $105 million, with Brazil spending $45

million.

Prior to the first CBERS launching, Satellite de

Coleta de Dados 1 (SCD-1) was orbited in 1992. This

first Brazilian-made satellite is an environmental data

collection satellite to be followed by an SCD-2 launch

48 China_Brazi/ Earth Re~ource~ Safe//ite-CBERS, I~titute de Pequisas Espaciais, Sao Jose dos CtimpOS, Brazil. [nO date]
Appendix D—Non-U.S. Earth Observation Satellite Programs I 185

in 1993. Each will be placed in 750-km orbits. Two

Sensoriarnento Remoto (SSR) satellites are also to be

launched, in 1995 and in 1996, respectively. Carrying

CCD cameras capable of 200-meter resolution, the

SSR-1 and SSR-2 are to be placed in 642-km,

sun-synchronous orbits.

The CBERS project completed its phase B work in

1989, when the preliminary design of the satellite was

completed. The project is currently in the development

and engineering phase with some contracts with

Brazilian industries established. Because of budget

difficulties, work on the project has been slowed.

Launch of the CBERS-1 appears now to be planned

for 1995, with the satellite placed in a 778-km

sun-synchronous orbit. CBERS-2 launch is targeted

for 1996. The CBERS five-channel linear CCD would

provide visible and panchromatic coverage. Spectral

bands would range from 0.51 microns to 0,89 microns.

Ground resolution of the CCD camera is 20 meters. A

CBERS infrared multispectral scanner would include

four channels between 0.5 and 12.5 microns. The

infrared multispectral scanner would yield an 80-meter

ground resolution, CBERS imagery is designed to

rival SPOT and Landsat data. China’s Great Wall

Industry Corp. and Brazil’s Avibras Aeroespacial in

1989 signed a joint venture agreement to establish

INSCOM, a company that would specialize in establishing a ground data handling network. Like China,

Brazil has a Landsat ground station, operating a facility

since 1973, A data processing center was established

there the following year.

INTERNATIONAL COOPERATION IN

REMOTE SENSING

Global climate change knows no national borders.

Satellite observations of the Earth, therefore, must in

time become a truly international activity. A myriad of

organizations now play key roles in the attempt to

coordinate the scientific study of Earth’s biosphere,

These include groups from the national and international scientific community; government agencies;

and intergovernmental science bodies.49

Key Organizations

The International Council of Scientific Unions

(ICSU)--created in 1931 as an autonomous federation

consisting of 20 disciplinary scientific unions and 70

national member organizations---has endorsed and

runs the International Geosphere-Biosphere Program

(IGBP) to help determine the interactive physical,

chemical and biological processes that regulate the

total Earth system, including the influences of human

actions on those processes.

The IGBP, in turn, involves the United Nations

(UN) World Meteorological Organization (WMO), the

United Nations Educational, Scientific, and cultural

Organization (UNESCO), and the United Nations

Environment Program (UNEP), which, in turn, is

coordinating the World Climate Research Program

(WCRP).

In 1988, the UN established the Intergovernmental

Panel on Climate Change (IPCC), sponsored jointly by

the WMO and the UNEP. The IPCC serves as a

primary international forum for addressing climate

change, with three working groups that: assess scientific evidence on climate change; assess likely impacts

resulting from such change; and consider possible

response strategies for limiting or adapting to climate

change.

As a member of ICSU, the National Academy of

Sciences’ National Research Council (NRC) participates in the IGBP through its Committee on Global

Change (CGC), which is reviewing the U.S. Global

Change Research Program (USGCRP). Another NRC

entity, the Committee on Earth Studies (CES), is

providing the federal government with advice on the

study of the Earth from space.

Remote sensing for environmental monitoring cuts

across territory, airspace and economic zones of the

Earth’s nation states, where the systematic exchange of

data or joint access will necessitate international

@ ~cla S, Smlh, and John R. JUWUS, Mission to PlanetEarth and the U.S. Globa[ Change Research Program, CRS Report for Conpss,

Congressional Research Service, 90-300 SPR, June 19, 1990; James D. Baker, “Observing Global Change from Space: Science &

Technology, ’ presented at Annual Meeting of the American Association for the Advancement of Science, Washingto% DC, February 1991;

C[imate Change: The IPCC Scienfrjic Assessment, J.T Houghton, G.J. Jenkins and J.J. Ephraums, eds., Cambridge University Press,

Cambridge, MA, 1990, pp. 315-328; Assessment of Satellite Earth Observation Programs-1991, Committee on Earth Studies, Space Studies

Board, Commission on Physical Sciences, Mathematics, and Applications, Nationat Research Council, Washington, DC, 1991; and Congress

of the United States, Office of Technology Assessmen4 Changing By Degrees: Steps to Reduce Greenhouse Gases (OZ4-OE-O-482,

Washington DC: U.S. Government Printing OffIce, February 1991), pp. 282-283.
186 I Remote Sensing From Space

agreement. Compatibility among observation systems,

data exchanges, and the setting of data product

standards is key to establishing a meaningful and

unified global research program of Earth observation.

A recent example of this is exploratory discussions

between the European Space Agency (ESA) and the

Japanese Minister for Science and Technology, who

also chairs Japan’s Space Activities Commission.50

Both parties agreed to study the prospects for wider

cooperation between ESA and Japan on observations

of the Earth and its environment, using next-generation

meteorological satellites. In addition, ESA and Japan

will study the relay of data by European and Japanese

data relay satellites.

The following paragraphs summarize the work of

three organizations that are attempting to coordinate

data gathered globally, or are wrestling with the policy

issues attendant to the acquisition and interpretation of

remote sensing information.

Consortium for International Earth Science

Information Network (CIESIN)

The U.S. Congress, on Oct. 18, 1989, mandated

through Public Law No. 101-144 an effort to “integrate and facilitate the use of information from

government-wide Earth monitoring systems” for understanding global change. The law stipulated that

NASA should take the lead in broadening the work

now planned for the Earth Observing System ‘‘to

create a network and the required associated facilities

to integrate and facilitate the use of information from

government-wide Earth monitoring systems. CIESIN

was chartered in October 1989 as a nonprofit corporation in the State of Michigan to accomplish this. The

founding members are the Environmental Research

Institute of Michigan (ERIM), Michigan State University, Saginaw Valley State University, and the University of Michigan.51 CIESIN membership has been

expanded to include New York Polytechnic Institute,

and the University of California.

According to CIESIN, the organizational mix brings

expertise in the fields of the natural Earth sciences,

remote sensing and its international applications,

public policy, the social sciences, electronic networking, media, and education. The group has been

established to enable scientists and policymakers to

model, predict, and understand global change on an

international scale. CIESIN has embarked on networking global change resources as an early priority.

Committee on Earth Observation Satellites

The Committee on Earth Observation Satellites

(CEOS) was created in 1984 as a result of recommendations from the Economic Summit of Industrialized

Nations. Members of CEOS are government agencies

with funding and program responsibilities for satellite

observations and data management. The United Kingdom served as CEOS secretariat in 1992. Japan will

host the CEOS plenary in 1993, followed by Germany

in 1994.

At the CEOS plenary level, agencies are represented

by the head of the agency or Earth observation

division: NOAA and NASA for the U. S., ASI (Wily),

BNSC (UK), CNES (France), CSA (Canada), CSIRO

(Australia), DARA (Germany), ESA (Europe), Eumetsat (Europe), INPE (Brazil), ISRO (India), STA

(Japan), and the Swedish National Space Board.

Governmental bodies with a space-based Earth

observation program in the early stages of development or with significant ground segment activities that

support CEOS member agency programs may qualify

for observer status. Current observers are agencies

from Canada, New Zealand, and Norway.

CEOS members intend for the organization to serve

as the focal point for international coordination of

space-related Earth observation activities, including

those related to global change. Policy and technical

issues of common interest related to the whole

spectrum of Earth observations satellite missions and

data received from such are to be addressed by CEOS.

CEOS has been successful in interacting with both

international scientific programs—ICSU/IGBP, WCRP

—as well as intergovernmental user organizationsIPCC, WMO, the Intergovernmental Oceanographic

Commission (IOC), the United Nations Environmental

Program (UNEP)-in order to enhance and further

focus space agency Earth observation mission planning on global change requirements.

~ 44ESA and Jap~ Meet on Space Cooperation” ESA News Release, No. 12, European Space Agency, park, fiance, -h11, 1~.

51 c ‘~omtion for a Changing World-Strategies for Integration and Use of Global Change hlfOrnlatiO%’ fi=utiveS~ of a Report

to Congress, Consortium for International Earth Science Information Network (CIESIN), May 15, 1991.
Appendix D—Non-U.S. Earth Observation Satellite Programs I 187

Space Agency Forum on ISY (SAFISY)

The International Space Year (ISY) of 1992 promulgated the establishment in 1988 of SAFISY, a coordination group of the world space agencies.52 SAFISY

provided a mechanism, through periodic meetings, for

the agencies to share ideas and pool resources in

connection with the International Space Year.

Panels of experts were established by SAFISY, two

of which are scientific in nature, The Panel of Experts

on Earth Science and Technology monitored projects

that are designed to provide worldwide assessment of

threats to the environment through satellite observations and the development of predictive models. The

Panel of Experts on Space Science monitored projects

under the theme ‘‘Perspectives from Space, ’ emphasizing that unlimited perspectives are gained through

all aspects of space science study and through venturing out into space<

A third SAFISY panel, Panel of Experts on Education and Applications, was geared to promote ISY

educational activities internationally, many of which

deal with satellite remote sensing.

52 sp~c~ &~~cy F~~mon ~~ ~tematio~Space Year-Third Meeting (SAFISY-3), NASDA CM-147, Kyoto, JaP~ MY 17-18> l~o.
Appendix E:

AATSR

ACR

ACRIM

ADEOS

AES

AIRS

ALEXIS

ALT

AMS

AMSR

AMSU

AMTS

APT

ARA

ARGOS

ARM

ASAR

ASCAT

ASF

ASTER

ATLAS

ATMOS

AVHRR

—Advanced Along-Track Scanning

Radiometer

—Active Cavity Radiometer

—Active Cavity Radiometer Ix-radiance

Monitor

—Advanced Earth Observing Satellite

—Atmospheric Environment Service

—Atmospheric Infrared Sounder

—Array of Low Energy X-Ray Imaging

Sensors

—Altimeter

—American Meteorological Society

—Advanced Microwave Scanning

Radiometer

—Advanced Microwave Sounding Unit

—Advanced Moisture and Temperature

Sounder

—Automatic Picture Transmission

—Atmospheric Radiation Analysis

—Argos Data Collection and Position

Loacation System

—Atmospheric Radiation Measurement

—Advanced Synthetic Aperture Radar

—Advanced Scatterometer

—Alaska SAR Facility

—Advanced Spaceborne Thermal

Emission and Reflection Radiometer

—Atmospheric Laboratory for

Applications and Science

—Atmospheric Trace Molecules

Observed by Spectroscopy

—Advanced Very High Resolution

Radiometer

AVIRIS

AVNIR

CCD

CCRS

CEES

CEOS

CERES

CES

CFC

CGC

CIESIN

CLAES

CNES

CNRS

COSPAR

CPP

CSA

CZCS

DAAC

DB

DCS

DDL

DMSP

DOC

Glossary

of

Acronyms

—Airborne Visible Infrared Imaging

Spectrometer

—Advanced Visible and Near-Infrared

Radiometer

—Charged Coupled Device

—Canada Centre for Remote Sensing

—Committee on Earth and

Environmental Sciences

—Committee on Earth Observations

Satellites

—Clouds and Earth’s Radiant Energy

System

—Committee on Earth Studies

— Chlorofluorocarbon

—Committee on Global Change

—Consortium for International Earth

Science Information Network

—Cryogenic Limb Array Etalon

Spectrometer

—Centre National d’Etudes Spatiales

—Centre National de la Recherche

Scientifique

—Congress for Space Research

—Cloud Photopolarimeter

—Canadian Space Agency

—Coastal Zone Color Scanner

—Distributed Active Archive Center

—Direct Broadcast

—Data Collection System

—Direct Downlink

—Defense Meteorological Satellite

Program

—Department of Commerce

189
190 I Remote Sensing From Space

DOD —Department of Defense

DOE —Department of Energy

DOI —Department of the Interior

DORIS —Doppler Orbitography and

Radiopositioning Integrated by

Satellite

DOS —Department of State

DPT —Direct Playback Transmission

DRSS —Data Relay Satellite System

EC —European Community

EDC —EROS Data Center

EDRTS —Experimental Data Relay and

Tracking Satellite

EOC —EOS Operations Center

EOS —Earth Observing System

EOS-AERO —EOS Aerosol Mission

EOS-ALT —EOS Altimetry Mission

EOS-AM —EOS Morning Crossing (Ascending)

Mission

EOSAT —Earth Observation Satellite company

EOS-CHEM-EOS Chemistry Mission

EOSDIS

EOSP

EOS-PM

EPA

ERBE

ERBS

EROS

ERS

ERTS-1

ESA

ESDIS

EWUN

ETS-VI

—EOS Data and Information System

—Earth Observing Seaming Polarimeter

—EOS Afternoon Crossing

(Descending) Mission

—Environmental Protection Agency

—Earth Radiation Budget Experiment

—Earth Radiation Budget Satellite

—Earth Resources Observation System

—European Remote-Sensing Satellite

—Earth Resources Technology

Satellite-1

—European Space Agency

—Earth Science Data and Information

System

—European Scientific Research Institute

—Engineering Test Satellite-VI

E UMETSAT-European Organization for the

Exploitation of Meteorological

Satellites

FCCSET —Federal Coordinating Council for

Science, Engineering, and Technology

FOV —Field-of-View

FST —Field Support Terminal

FY —Feng Yun

GCDIS —Global Change Data and Information

System

Geosat —Navy Geodetic Satellite

GEWEX

GGI

GLAS

GLI

GLRS

GMS

GOES

GOMI

GOMOS

GOMR

GOMS

GPS

HIRDLS

HIRIS

HIRS

HIS

HYDICE

ICSU

IGBP

ILAS

INSAT

IMG

IPCC

IRS

IRTS

ISAMS

ISY

JERS

JOES

JPL

JPOP

LAGEOS

—Global Energy and Water Cycle

Experiment

—GPS Geoscience Instrument

—Geoscience Laser Altimeter System

—Global Imager

—Geoscience Laser Ranging System

—Geostationary Meteorological

Satellite

—Geostationary Operational

Environmental Satellite

—Global Ozone Monitoring Instrument

—Global Ozone Monitoring by

Occultation of Stars

—Global Ozone Monitoring Radiometer

—Geostationary Operational

Meteorological Satellite

—Global Positioning System

—High-Resolution Dynamics Limb

Sounder

—High-Resolution Imaging

Spectrometer

—High-Resolution Infrared Sounder

—High-Resolution Interferometer

Sounder

—High-Resolution Picture Transmission

—Hyperspectral Digital Imagery

Collection Experiment

—International Council of Scientific

Unions

—International Geosphere-Biosphere

program

—Improved Limb Atmospheric

Spectrometer

—Indian National Satellite

—Interferometric Monitor for

Greenhouse Gases

—Intergovernmental Panel on Climate

Change

—Indian Remote Sensing Satellite

—Infrared Temperature Sounder

—Improved Stratospheric and

Mesospheric Sounder

—International Space Year

—Japan Earth Resources Satellite

—Japanese Earth Observing System

—Jet Propulsion Laboratory

—Japanese Polar Orbiting Platform

—Laser Geodynamics Satellite .
Appendix E—Glossary of Acronyms I 191

Landsat

Lidar

LIMS

LIS

LISS

LITE

LR

MERIS

MESSR

METOP

MHS

MIPAS

MISR

MODIS

MOP

MOPITT

MOS

MSR

MSS

MSU

MTPE

MTS

NASA

NASDA

NESDIS

NOAA

NREN

NRSA

NSCAT

NSPD

OCTS

OLS

—Land Remote-Sensing Satellite

—Light Detection and Ranging

—Limb Infrared Monitor of the

Stratosphere

—Lightning Imaging Sensor

—Linear Imaging Self-scanning Sensors

—Lidar In-Space Technology

Experiment

—Laser Retroreflector

—Medium-Resolution Imaging

Spectrometer

—Multispectrum Electronic SelfScanning Radiometer

—Meteorological Operational Satellite

—Microwave Humidity Sounder

—Multifrequency Imaging Microwave

Radiometer

—Michelson Interferometer for Passive

Atmospheric Sounding

—Multi-Angle Imaging

SpectroRadiometer

—Microwave Limb Sounder

—Moderate-Resolution Imaging

Spectroradiometer

—Meteosat Operational Programme

—Measurements of Pollution in the

Troposphere

—Marine Observation Satellite

—Microwave Scanning Radiometer

—Multispectral Scanner

—Microwave Sounding Unit

—Mission to Planet Earth

—Microwave Temperature Sounder

—National Aeronautics and Space

Administration

—National Space Development Agency

(Japan)

—National Environmental Satellite, Data,

and Information Service

—National Oceanic and Atmospheric

Administration

—National Research and Education

Network

—National Remote Sensing Agency

—NASA Scatterometer

—National Space Policy Directive

—Ocean Color and Temperature Scanner

—Optical Line Scanner

OMB —Office of Management and Budget

OPS —Optical Sensors

OSC —Orbital Sciences Corporation

OSIP —operational Satellite Improvement

Program

POEM —Polar-Orbit Earth Observation

POES

POLDER

RA

Radarsat

RESTEC

RF

RIS

SAFIRE

SAFISY

SAGE

SAMS

SAR

SARSAT

or S&R

SBUV

SCARAB

SeaWiFS

SEDAC

SEM

S-GCOS

SIR-C

SLR

SMMR

SOLSTICE

SPOT

SSM/I

SSU

STIKSCAT

Mission

—Polar-orbiting Operational

Environmental Satellite

—Polarization and Directionality of Earth’s

Reflectance

—Radar Altimeter

—Radar Satellite

—Remote Sensing Technology Center

—Radio Frequency

—Retroreflector in Space

—Spectroscopy of the Atmosphere using

Far Infrared Emission

—Space Agency Forum on ISY

—Stratospheric Aerosol and Gas

Experiment

—Stratopheric and Mesospheric Sounder

—Synthetic Aperture Radar

—Search and Rescue Satellite Aided

Tracking System

—Solar Backscatter Ultraviolet

Radiometer

—Scanner for the Radiation Budget

—Sea-Viewing Wide Field Sensor

—Socio Economic Data Archive Center

—Space Environment Monitor

—Space-based Global Change

Observation System

—Shuttle Imaging Radar-C

—Satellite Laser Ranging

—Scanning Multispectral Microwave

Radiometer

—Solar Stellar Irradiance Comparison

Experiment

—System Probatoire d’Observation de la

Terre

—Special Sensor Microwave/Imager

—Stratospheric Sounding Unit

—Stick Scatterometer
192 I Remote Sensing From Space

SWIR

TDRSS

TIROS

TM

TOMS

TOGA

TOPEX

TUSK

UARS

UAVS

UNEP

UNESCO

—Short Wave Infrared

—Tracking and Data Relay Satellite

System

—Television Infrared Observing Satellites

—Thematic Mapper

—Total Ozone Mapping Spectrometer

—Tropical Ocean Global Atmosphere

—Ocean Topography Experiment

—Tropical Rainfall Measuring Mission

— Tethered Upper Stage Knob

—Upper Atmosphere Research Satellite

—Unpiloted Air Vehicles

—United Nations Environment Program

—United Nations Educational, Scientific,

and Cultural Organization

USDA

USGCRP

USGS

VISSR

VTIR

WCRP

WEU

WMO

WOCE

X-SAR

—U.S. Department of Agriculture

—U.S. Global Change Research

Program

—U.S. Geological Survey

—Very High Resolution Radiometer

—Visible and Infrared Spin Scan

Radiometer

—Visible and Thermal Infrared

Radiometer

— World Climate Research program

—Western European Union

—The U.N. World Meteorological

Organization

—World Ocean Circulation Experiment

—X-Band Synthetic Aperture Radar
Index

ACRIM. See Active Cavity Radiometer Irradiance Monitor

Active Cavity Radiometer L-radiance Monitor

description, 69, 134

EOS-Chem, 107

ADEOS. See Advanced Earth Observation Satellite

Administration La.ndsat Management Plan, 48,50

Advanced Earth Observation Satellite, 24, 177-178

Advanced Microwave Sounding Unit

EOS-PM, 107

METOP platform, 41

Advanced Research Projects Agency

CAMEO program, 75

space technology initiatives, 138-139

Advanced Spaceborne Thermal Emission and Reflection

radiometer, 106

Advanced Technology Demonstrations, 75, 138-139

Advanced Technology Standard Satellite Bus, 75, 138

Advanced Very High Resolution Radiometer

AVHHR/2, 40

METOP platform, 41

research cooperation between NASA and NOAA, 36

Advanced Visible and Near Infrared Radiometer, 177-178

Air Force Space Command, 15

Aircraft, piloted and unpiloted, 78-79, 124-128

AIRS. See Atmospheric Infrared Sounder

Almaz, 61, 181

Altimeters

description, 6

ocean remote sensing, 56, 57

AMSU. See Advanced Microwave Sounding Unit

APT. See Automatic Picture Transmission recorders

ARGOS Data Collection System, 40

ARM. See Atmospheric Radiation Measurement program

Arms control monitoring, 82, 161-162, 163

ARPA. See Advanced Research Projects Agency

ASTER. See Advanced Spaceborne Thermal Emission and

Reflection radiometer

ATDs. See Advanced Technology Demonstrations

Atmospheric Infrared Sounder, 37, 107

Atmospheric Radiation Measurement program, 70

ATSSB. See Advanced Technology Standard Satellite Bus

Aurora Flight Services, Inc., 79

Automatic Picture Transmission recorders, 39

AVHRR. See Advanced Very High Resolution Radiometer

AVNIR. See Advanced Visible and Near Infrared

Radiometer

Balloons, 78-79

Bhaskara series, 181

Broad area search, 155-158

Bromley, D. Allan, 100

Budgets

costs of remote sensing, 24-25

DoD’s remote sensing systems, 18

global change research program, 13

NASA’s remote sensing systems, 18-23

NOAA’s remote sensing systems, 18, 23-24

reduction of NASA’s Earth Observing System program,

17-18,65-68

CAMEO. See Collaboration on Advanced Multispectral

Earth Observation

Camouflage, Concealment, and Deception, 162-163

Canada, remote sensing satellite, 57

CBERS. See China-Brazil Earth Resources Satellite

CC&D. See Camouflage, Concealment, and Deception

CEES. See Committee on Earth and Environmental Science

Centre Nationale d’Etudes Spatial, 52-53

CEOS. See Committee on Earth Observations Systems

CERES. See Clouds and Earth’s Radiant Energy System

China, satellite programs, 183-185

China-Brazil Earth Resources Satellite, 184-185

193
194 I Remote Sensing From Space

CIESIN, See Consortium for International Earth Science

Information Network

CIS. See Commonwealth of Independent States

Civilian space program

future of, 11-13

market motives, 164

military use, 81-84, 145-164

satellite characteristics, 148-154

Climate change. See also Global change

current state of research, 96-100

geostationary satellite system, 34-37

human influence, 113

meteorological satellite system, 4244

non-U.S. environmental satellite systems, 44-45

observations of satellite sensors, 33-34

polar-orbiting satellite system, 37-43

Climate feedbacks, 76, 112

Climate forcings, 76, 112-113

Climsat, 76-77, 131-135

Clinton administration, NASA budget request, 20

Clouds and Earth’s Radiant Energy System, 105, 129-131

CNES. See Centre Nationale d’Etudes Spatial

CO2 change, 132, 133

Coastal Zone Color Scanner, 55

Collaboration on Advanced Multispectral Earth

Observation, 75, 138

Combat intelligence, 159-161

Committee on Earth and Environmental Sciences, 13,63-64

Committee on Earth Observations Systems, 31,90, 186

Commonwealth of Independent States

earth observation satellite programs, 179-181

environmental satellite system, 44-45

Congressional considerations

comparing costs and benefits of global change research,

25-26

consolidation of DoD’s meteorological system and NOAA’s

polar-orbiting system, 16,44

cost reduction for remote sensing systems, 87-88

Earth Observing System funding, 65

future of space-based remote sensing, 2-3

global change data collection continuity, 27

improved calibration sensitivity of NOAA sensors, 14-15

international cooperation in remote sensing programs, 71

land remote sensing support, 27-28

Landsat sensors funding, 50

Landsat technology development funding, 52

military uses of civilian remote sensing data, 165

NASA’s funding plans for Mission to Planet Earth, 23,

68-69

non-space-based research support, 17

planning for development of Landsat 8,52

private satellite industry support, 87

private sector use of land remote sensing, 28,85-87

research cooperation between NASA and NOAA, 36-37

small satellite systems support, 75

unpiloted air vehicles funding, 79, 128

Consortium for International Earth Science Information

Network, 186

CZCS. See Coastal Zone Color Scanner

DAACS. See Distributed Active Archive Centers

Data gathering, 4

DCS. See ARGOS Data Collection System

Defense Meteorological Satellite Program

future of, 15-16, 17

weather observations, 4244

Department of Defense

collaborative projects with NASA, 70

developing a strategic plan for remote sensing, 26-27

Landsat program, 48-52

meteorological satellite system, 15-16, 42-44

remote sensing budget, 18

Department of Energy, strategic plan for remote sensing,

26-27

Distributed Active Archive Centers, 73, 103

DMSP. See Defense Meteorological Satellite Program

DOD. See Department of Defense

DOE. See Department of Energy

Earth Observation-Intemational Coordination Working Group,

31

Earth Observation Satellite Company, 49, 85

Earth Observing Scanning Polarimeter

Climsat, 133, 135

description, 106

Earth Observing System

current state of climate research, 96-100

description, 16-18,95-96, 101-107

EOS Aero, 106

EOS-Alt, 107

EOS-AM, 105-106

EOS-Chem, 107

EOS Color, 106

EOS Phase One, 104-105

EOS-PM, 106-107

global change research, 65-72,73

instruments not funded, 116-124

program, 71

and related systems, 101-104

restructured program, 69

science and policy priorities, 68

technology and the restructured program, 110-124

Earth Observing System Data and Information System

description, 102-104

global change research, 65-72,73

improving the use of research data, 29-30
Index I 195

Earth Probe satellites, 67

Earth Radiation Budget Experiment, 41, 131

Earth Resources Satellite, 57-58, 176-177

El Nino, 55,97, 132

Electro-optical sensors, 47

Enhanced Thematic Mapper, 50-51

Environmental change. See Global change

ENVISAT platform, 41

EO-ICWG. See Earth Observation-International

Coordination Working Group

EOS. See Earth Observing System

EOSAT. See Earth Observation Satellite Company

EOSDIS. See Earth Observing System Data and Information

System

EOSP. See Earth Observing Sc anning Polarimeter

ERBE. See Earth Radiation Budget Experiment

ERS. See European Remote Sensing Satellite

ERS-1. See Earth Resources Satellite

ESA. See European Space Agency

ETM. See Enhanced Thematic Mapper

Eumetsat. See European Organization for the Exploitation of

Meteorological Satellites

Europe

coordination of satellite research, 31

earth observation satellite programs, 167-175

European Organization for the Exploitation of

Meteorological Satellites

description, 168

environmental satellite system, 44

loan of Meteosat-3 to U. S., 34-35

METOP polar platform, 39,41

European Remote Sensing Satellite, 168-173

European Space Agency

environmental satellite system, 44

loan of Meteosat-3 to U. S., 34-35

METOP polar platform,41

ocean remote sensing satellite, 57-58

Fanhui Shi Weixing recoverable satellite, 184

FCCSET. See Federal Coordinating Council for Science,

Engineering, and Technology

Federal Coordinating Council for Science, Engineering

Sciences, and Technology, 13,63

Feng Yun, 183-184

Filter wedge, 14

Flux divergence, 79-80

France

land remote sensing system, 52-53, 173-175

ocean remote sensing, 58, 175

FSW. See Fanhui Shi Weixing recoverable satellite

Funding. See Budgets

FY. See Feng Yun

GCMS. See General circulation models

General circulation models, 95,96

Geodesy satellite

description, 61

Geosat Follow On, 61

Geographic information systems, 85-86

Geosat. See Geodesy satellite

Geoscience Laser Ranging System and Altimeter, 107

Geostationary Meteorological Satellites, 44, 175-176

Geostationary Operational Environmental Satellites

future of, 14

weather observations, 34-37

Geostationary Operational Environmental Satellites-Next

cost performance, 23

description, 35-36

development problems, 36, 38-39

GIS. See Geographic information systems

Global change. See also Climate change; Earth Observing

System

contribution of space-based remote sensing, 13

COStS, 25, 26

data collection continuity, 25-26

improving the use of research data, 29-31

international cooperation, 89-91

operational meteorological satellite systems, 14-15

research program budgets, 13

U.S. research program, 28-30,63-64

Global Change Data and Information System, 29

Global Habitability Program, 101

Global Positioning System, 83

GPS Geoscience Instrument, 107

Global Wa.rmin g, 98-99

GLRS-A. See Geoscience Laser Ranging System and

Altimeter

GMS. See Geostationary Meteorological Satellites

GOES. See Geostationary Operational Environmental

Satellites

GPS. See Global Positioning System

Greenhouse effect, 98-99, 115-116

Ground resolution, 81, 148

Helios, 174-175

High Resolution Dynamics Limb Sounder, 107

High-Resolution Imaging Spectrometer, 123-124

High Resolution Infrared Radiation Sounder, 40

High Resolution Multispectra1 Stereo Imager, 50-51

High Resolution Picture Transmission recorders, 39

HIRDLS. See High Resolution Dynamics Limb Sounder

HIRIS. See High-Resolution Imaging Spectrometer

HIRS/2. See High Resolution Infrared Radiation Sounder

HRMSI. See High Resolution Multispectral Stereo Imager

HRPT. See High Resolution Picture Transmission recorders

Hughes STX Corporation, 61
196 I Remote Sensing From Space

Hyperspectral imaging systems, 123-124, 139, 140

Ice caps. See Ocean remote sensing

IEOS, See International Earth Observing System

IIRS. See Image Interpretability Rating Scale

ILAS. See Improved Limb Atmospheric Spectrometer

Image Interpretability Rating Scale, 149

Imaging radiometer, 6

IMG. See Interferometric Monitor for Greenhouse Gases

Improved Limb Atmospheric Spectrometer, 177

India

earth observation satellite program, 181-183

ground facilities, 183

land remote sensing system, 53

Indian National Satellite system, 182

Indian Remote Sensing Satellite

description, 53, 182-183

follow-on series, 183

Indian Space Research Organization, 181

Indications and Warning, 158-159

Insat. See Indian National Satellite system

Interferometric Monitor for Greenhouse Gases, 177-178

Intergovernmental Panel on Climate Change, 65

International cooperation, 89-93, 186-187

International Earth Observing System, 90

IPCC. See Intergovernmental Panel on Climate Change

IRS. See Indian Remote Sensing Satellite

ISRO. See Indian Space Research Organization

I&W. See Indications and Warning

Japan

data distribution, 178-179

earth observation satellite program, 175-178

environmental satellite system, 44

future planning, 178

land remote sensing, 53-54

ocean remote sensing, 58

Japan Earth Resources Satellite, 53-54, 176-177

JERS-1. See Japan Earth Resources Satellite

Land remote sensing

applications, 8, 10

description, 47-48

France, 52-53, 173-175

India, 53

Japan, 53-54, 176-177

Landsat program, 48-52

Russia, 54

Land Remote Sensing Commercialization Act of 1984,49

Land Remote Sensing Policy Act of 1992

continuity of data collection and use, 25-26

introduction of legislation, 48

shift of operational control of Landsat, 27, 48

technology development program, 51-52

Landsat program

description, 48,49

developing follow-ens, 140-144

future satellites, 51-52

Landsat 7,48,50-51

military uses, 81-84

role of private sector, 85-86

use of data, 27-28

Laser Atmospheric Wind Sounder, 116-118

LAWS. See Laser Atmospheric Wind Sounder

Lidar altimeter, 6

Linear Imaging Self-searming Sensors, 53, 182

LISS. See Linear Imaging Self-searming Sensors

Mapping, Charting, and Geodesy, 82-84

description, 147-148

use of civilian satellites, 154-155

Marine Observation Satellite, 58, 176

MC&G. See Mapping, Charting, and Geodesy

Measurements of Pollution in the Troposphere, 106

MESSR. See Multispectral Electronic Self-scanning

Radiometer

Meteor satellites, 179-180

Meteosat Operational Programrne, 167-168

Meteosat satellites

description, 44, 167-168

loan to U. S., 34-36

METOP polar platform, 41

MHS. See Microwave Humidity Sounder

Michelson Interferometer, 135

Microwave Humidity Sounder, 107

Microwave Imager, 42

Microwave Limb Sounder, 107

Microwave Scanning Radiometer, 58

Microwave Sounding Unit, 40

Microwave Temperature Sounder, 42

Microwave Water Vapor Sounder, 42

Military operations

civilian satellite characteristics, 148-154

issues for Congress, 165

market motives, 164

remote sensing missions, 145-148

use of civilian satellites, 81, 154-165

MIMR. See Multifrequency Imaging Microwave Radiometer

MINT. See Michelson Interferometer

Mir space station, 181

MISR. See Multiangle Imaging Spectra-Radiometer

Mission to Planet Earth

budget, 18-23

current research efforts, 101

description, 16-18

global change research, 65-72,73
Index I 197

improving the use of research data, 29

new technology for, 136-137

ML-S. See Microwave Limb Sounder

Moderate Resolution Imaging Spectrometer, 105-106

MODIS. See Moderate Resolution Imaging Spectrometer

MOP. See Meteosat Operational Programme

MOPITT See Measurements of Pollution in the Troposphere

MOS. See Marine Observation Satellite

MPIR. See Multispectral Pushbroom Imaging Radiometer

MSR. See Microwave Scanning Radiometer

MSU. See Microwave Sounding Unit

MIT. See Multispectral Thermal Imager

MTPE. See Mission to Planet Earth

Multiangle Imaging Spectra-Radiometer, 106

Multifrequency Imaging Microwave Radiometer, 107

Muhispectral Electronic Self-searming Radiometer, 58

Multispectral Pushbroom Imaging Radiometer, 138

Multispectral Thermal Imager, 140-141

N-ROSS. See Navy Remote Ocean Sensing Satellite

NASA. See National Aeronautics and Space Administration

National Aeronautics and Space Act of 1958, 12

National Aeronautics and Space Administration

cooperative research development with NOAA, 36-39

developing a strategic plan for remote sensing, 26-27

global change research, 65-72,73

global research budget, 13

Landsat program, 48-52

Mission to Planet Earth, 16-18, 101-107

remote sensing budget, 18-23

National Environmental Satellite, Data, and Information

Service, 14, 24

National Natural Resources Management System, 53

National Oceanic and Atmospheric Administration

data processing coordination with DoD, 42,43-44

developing a strategic plan for remote sensing, 26-27

environmental earth observations, 14-15

the geostationary satellite system, 34-37, 38-39

the polar-orbiting satellite system, 37-43

remote sensing budget, 18, 23-24

National Oceanic Satellite System, 56

National Remote Sensing Agency, 183

National Space Policy Directive 7,28

National Weather Service, 14,34

Navy Remote Ocean Sensing Satellite, 56

NESDIS. See National Environmental Satellite, Data, and

Information Service

Nimbus 7, 55

NNRMS. See National Natural Resources Management

System

NOAA. See National Oceanic and Atmospheric

Administration

NOSS. See National Oceanic Satellite System

NRSA. See National Remote Sensing Agency

NSPD7. See National Space Policy Directive 7

Ocean Color and Temperature Scanner, 177-178

Ocean remote sensing

Canada, 57

description, 54-55

European Space Agency, 57-58, 168, 172

France, 58, 175

Japan, 58, 176

observations of sea ice, 56-57

operational uses of ocean satellites, 56

Orbital Sciences Corp., 59,61

research of ocean phenomena, 55-56

Russia, 61, 180

sensor design and selection, 60, 61

United States, 61

United States/France, 58, 175

OCTS. See Ocean Color and Temperature Scanner

Office of Science and Technology Policy, 31

Okean-0, 180

OLS. See operational Linescan System

Operational Linescan System, 42

Operational Satellite Improvement Program, 36,38

Orbital Sciences Corporation, 59,61

OSC. See Orbital Sciences Corporation

OSIP, See Operational Satellite Improvement Program

Ozone depletion, 102, 115. See also Radiative forcings

Perseus, 79, 127-128

Platforms

role of small satellites, 128

satellite v. non-satellite data collection, 124-125

unpiloted air vehicles, 125-128

POEM. See Polar Orbit Earth Observation Mission

POES, See Polar-orbiting Operational Environmental

Satellite

Polarization and Directionality of the Earth’s Reflectance,

177-178

Polar Orbit Earth Observation Mission, 41

Polar-orbiting Operational Environmental Satellite

future of, 14-15

weather observations, 37-43

POLDER. See Polarization and Directionality of the Earth’s

Reflectance

Private sector

partnership with government for system development,

92-93

role in remote sensing, 85-88

use of land remote sensing, 28, 85-88

Process studies, 79-80

Pushbroom detectors, 139, 142-143
198 I Remote Sensing From Space

Radar altimeters

description, 6

ocean remote sensing, 57

Radarsat, 57

Radar sensors, 6

Radiation budget, 8,79, 129-131

Radiative feedbacks, 76, 112

Radiative forcings, 76, 112-113

Radiometers. See also Advanced Very High Resolution

Radiometer

imaging, 6

ocean remote sensing, 57

polar-orbiting operational environmental satellites, 40,41

Radiometric resolution, 60

Radiosondes, 41

Reagan Administration, NASA funding, 38

Reconnaissance, 81-82, 146-147

Remote Sensing Technology Center of Japan, 58, 178-179

Resolution, role in military detection, 148-151

RESTEC. See Remote Sensing Technology Center of Japan

Resurs satellites, 54, 180-181

Retroreflector in Space, 177

RIS. See Retroreflector in Space

Rohini series, 181

Russia

environmental satellite system, 44-45, 179-180

land remote sensing, 54, 180-181

MIR space station, 181

ocean remote sensing, 61, 180-181

possible coordination of satellite research, 31

S-GCOS. See Space-based Global Change Observation

System

SAFISY. See Space Agency Forum on International Space

Year

SAGE III. See Stratospheric Aerosol and Gas Experiment

Santa Barbara Research Center, 144

SAR. See Synthetic Aperture Radar

SARSAT. See Search and Rescue Satellite Aided Tracking

System

Satellite de Coleta de Dados, 184-185

satellites

applications of remote sensing, 6-10

benefits of remote sensing, 22,24-25

control, 153

costs, 24-25, 153, 154

current remote sensing systems, 2, 72-73

earth monitoring satellites, 3

international coordination of research, 31

metric, 152

military use against U. S., 162-164

NOAA’s operational meteorological systems, 14-15

nonsatellite data, 77-78, 124-125

role of private sector, 85-88

small systems, 73-76, 128-129

spectrum, 151

stereoscope, 151-152

throughput, 153

timeliness, 152-153

USe in military operateions, 154-162

SBRC. See Santa Barbara Research Center

SBUV/2. See Solar Backscatter Ultraviolet Radiometer/2

Scanning Multichannel Microwave Radiometer, 55

Scatterometer

aboard ADEOS satellite, 24

description, 6

EOS Phase One, 105

NASA, 177-178

ocean remote sensing, 56, 57

SCD. See Satellite de Coleta de Dados

Sea ice. See Ocean remote sensing

Sea-viewing Wide Field of view Sensor

EOS Color, 106

EOS Phase One, 104

surface remote sensing, 59, 61

Search and Rescue Satellite Aided Tracking System, 40

Seasat, 55-56

SeaStar satellite, 59,61,87

SeaWiFS. See Sea-viewing Wide Field of view Sensor

SEM. See Space Environment Monitor

Sensoriamento Remoto satellites, 185

Sensors

applications, 6-10

design and selection, 60,61

developing new systems, 28

how SensOrS WOrk, 5-6

for land remote sensing, 49-50

research cooperation between NASA and NOAA, 36-37

Shuttle Imaging Radar, 118, 123

Shuttle orbiters, 22

SIMS. See Small Imaging Multispectral Spectrometer

SIR-C. See Shuttle Imaging Radar

Small Imaging Multispectral Spectrometer, 140

SMMR. See Scanning Multichannel Microwave Radiometer

Solar BackScatter Ultraviolet Radiometer/2,40

Solar radiation, 6,7

Sounders, 6,37,40

Space Agency Forum on International Space Year, 187

Space-based Global Change Observation System, 28-29

Space Environment Monitor, 40

Space program

applications of remote sensing, 6-10

collecting routine earth observations, 27-28

developing a strategic plan for remote sensing, 26-27

future of civilian program, 11-13

global change research, 28-29
Index I 199

improving the use of data, 29-30

remote sensing defintion, 5

role of private sector, 85-88

U.S. space policy, 90

Spectral resolution, 60, 151

SPOT. See Systeme Pour d’Observation de la Terre

S&R. See Search and Rescue Satellite Aided Tracking

System

SSR. See Sensoriamento Remoto satellites

SSU. See Stratospheric Sounding Unit

Stratospheric Aerosol and Gas Experiment

Climsat, 133, 135

EOS Aero, 106

Stratospheric Sounding Unit, 40

Surface remote sensing. See also Land remote sensing;

Ocean remote sensing

international cooperative development program, 92

Synthetic Aperture Radar

description, 118-123

ocean remote sensing, 56-58, 61

Systeme Pour d’Observation de la Terre

description, 52-53, 173-174

military uses, 81-84

SPOT Image, S. A., 53

Technology issues

developing advanced remote sensing systems, 135-141

EOS program restructuring, 110-124

Landsat follow-ens, 140-144

overview, 109-110

platforms, 124-135

Television Infrared Observing Satellites, 14-15

Temporal resolution, 60

TES. See Tropospheric Emission Spectrometer

TIROS. See Television Infrared Observing Satellites

TOMS. See Total Ozone Mapping Spectrometer

TOPEX/Poseidon

description, 58, 175

EOS Phase One, 105

Total Ozone Mapping Spectrometer

EOS Phase One, 104-105

NASA, 177-178

polar-orbiting satellite, 41

research cooperation between NASA and NOAA, 36

TRMM. See Tropical Rainfall Measurement Mission

Tropical Rainfall Measurement Mission, 105

Tropospheric Emission Spectrometer, 106

UARS. See Upper Atmosphere Research Satellite

UAVS. See Unpiloted air vehicles

Unpiloted air vehicles

advantages, 125-128

description, 79-80, 125-126

Perseus, 127-128

specifications, 127

Upper Atmosphere Research Satellite

cost performance, 23

global change research, 69,70

project goals, 105

U.S. Global Change Research Program

Climsat, 76-77

complementing satellite measurements, 77-78

coordination of global change research, 28-29

current research efforts, 100

description, 63-64

existing satellite systems, 72-73

Mission to Planet Earth, 65-72

non-space-based research, 17

process studies, 79-80

program structure, 72

purpose, 13

small satellites, 73-76

unpiloted air vehicles, 79-80

USGCRP. See U.S. Global Change Research Program

Value-added services, 85-86

Visible and ThermaI Infrared Radiometer, 58

VTIR. See Visible and Thermal Infrared Radiometer

Weather monitoring

geostationary satellite system, 34-37

international cooperation, 90

meteorological satellite system, 42-44

non-U.S. environmental satellite systems, 44-45

observations of satellite sensors, 33-34

operational meteorological satellite systems, 14-15

polar-orbiting satellite system, 37-43

Wedge Spectrometer, 144

Wide Field Sensor, 53

WiFS. See Wide Field Sensor

Wind scatterometer, 57

WMO. See World Meteorological Organization

World Meteorological Organization, 35,41,90

WorldView Imaging Corporation, 87