NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

                       SPACE SHUTTLE MISSION

                         STS-46 PRESS KITT

                             JULY 1992

PUBLIC AFFAIRS CONTACTS

NASA Headquarters

Office of Space Flight/Office of Space Systems Development
Mark Hess/Jim Cast/Ed Campion
(Phone:  202/453-8536)

Office of Space Science and Applications
Paula Cleggett-Haleim/Mike Braukus/Brian Dunbar
(Phone:  202/453-1547)

Office of Commercial Programs
Barbara Selby
(Phone:  703/557-5609)

Office of Aeronautics and Space Technology
Drucella Andersen/Les Dorr
(Phone:  202/453-2754)

Office of Safety & Mission Quality/Office of Space 
Communications
Dwayne Brown
(Phone:  202/453-8596)

Ames Research Center			Langley Research Center
Jane Hutchison				Jean Drummond Clough
(Phone:  415/604-4968)			(Phone:  804/864-6122)

Dryden Flight Research Facility		Lewis Research Center
Nancy Lovato    			Mary Ann Peto
(Phone:  805/258-3448)			(Phone:  216/433-2899)
 
Goddard Space Flight Center		Marshall Space Flight Center
Dolores Beasley				Mike Simmons
(Phone:  301/286-2806)			(Phone:  205/544-6537)

Jet Propulsion Laboratory		Stennis Space Center
James Wilson				Myron Webb
(Phone:  818/354-5011)			(Phone:  601/688-3341)

Johnson Space Center			Wallops Flight Center
James Hartsfield			Keith Koehler
(Phone:  713/483-5111)			(Phone:  804/824-1579)

Kennedy Space Center
Lisa Malone
(Phone:  407/867-2468)

CONTENTS

General Release                                1

Media Services Information                     4

Quick-Look-Facts                               5

Summary of Major Activities                    6

Payload and Vehicle Weights                    7

Trajectory Sequence of Events                  8

Space Shuttle Abort Modes                      9

Prelaunch Processing                          10

Tethered Satellite System (TSS-1)             12

European Retrievable Carrier (EURECA)         34

Evaluation of Oxygen Interaction with
Materials (EOIM)/Two Phase Mounting Plate
Experiment (TEMP)                             47

Consortium for Materials Development 
in Space (Complex Autonomous Payload)          49

Limited Duration Space Environment
Candidate Materials Exposure (LDCE)            50

Pituitary Growth Hormone Cell Function (PHCF)  52

IMAX Cargo Bay Camera (ICBC)                   52

Air Force Maui Optical Station (AMOS)          55

Ultraviolet Plume Imager (UVPI)                55

STS-46 Crew Biographies                        55

Mission Management for STS-46                  58

Previous Shuttle Flights                       60

Upcoming Space Shuttle Flights                 61

Release:  92-95

49TH SHUTTLE FLIGHT TO TEST FEASIBILITY OF TETHERED SATELLITE

     Highlighting Shuttle mission STS-46 will be experiments 
involving a 12.5-mile-long tether connecting a satellite to 
the orbiter Atlantis, to demonstrate the feasibility of the 
technology for a variety of uses ranging from generating 
electrical power to researching the upper atmosphere.

     During the mission the crew also will deploy the 
European Retrievable Carrier (EURECA-1) platform, which 
contains a series of experiments dealing with materials 
sciences, life sciences and radiobiology.  The platform will 
remain in orbit for about 9 months before being retrieved 
during a later Shuttle mission.

     "First and foremost, this is a mission of discovery," 
Thomas Stuart, Tethered Satellite System Program Manager 
said.

     "It's the first time we've ever deployed a satellite on 
a long tether in space.  This system is at the leading edge 
of scientific discovery and will give us a glimpse of space 
technologies of the future," he said.

     STS-46 is scheduled for launch in late July.  It will be 
the 12th flight for Atlantis, and is scheduled to last 6 
days, 22 hours and 11 minutes, with a planned landing at 
Kennedy Space Center, Fla.

TETHERED SATELLITE SYSTEM

     The Tethered Satellite System-1 (TSS-1) -- a joint 
project of the United States and Italy under an agreement 
signed in 1984 -- consists of a satellite, a 1/10th inch 
diameter tether and a deployer in the Shuttle's cargo bay.

     The 1,139 pound satellite was developed by the Italian 
Space Agency (ASI) and the tether and deployer system were 
developed by the U.S.  The 12 main experiments were selected 
jointly by NASA and ASI.

     "During this mission we're going to learn a great deal 
about how to safely operate a tether system," Stuart said.  
"We're going to demonstrate the feasibility of usinf a tether 
to generate electricity, as a propulsion system to power 
spacecraft and for studying the Earth's magnetic field and 
ionosphere."

     When the tether is fully extended to its 12 1/2 mile 
length, the combination of the orbiter, tether and satellite 
combined will be the longest structure ever flown in space.

EURECA

     The crew will deploy the European Space Agency's (ESA) 
EURECA-1, which will then ascend to its operational orbit of 
515 km using its own propulsion system.  After 9 months it 
will be moved to a lower orbit for retrieval by another 
Shuttle in late April 1993.  After its return to Earth it 
will be refurbished and equipped for its next mission.

     Aboard EURECA-1 are 15 experiments devoted to 
researching the fields of material science, life sciences and 
radiobiology, all of which require a controlled microgravity 
environment.  The experiments include:

     O protein crystallization
     O biological effects of space radiation
     O measurements of fluids' critical points
         in microgravity
     O measurements of solar irradiation
     O solar/terrestrial relationship in aeronomy
          and climatology
     O electric propulsion in space

     Scientists participating in the investigations are from 
Belgium, Germany, Denmark, France, Italy, United Kingdom and 
The Netherlands.

     EURECA-1 was built by the ESA and designed to be 
maintained during its long-term mission by ground controllers 
at ESA's Space Operations Centre (ESOC), Darmstadt, Germany.

ADDITIONAL PAYLOADS

     Additional payloads carried in Atlantis' cargo bay 
include the:

     O Evaluation of Oxygen Interaction with Materials III 
(EOIM) experiment to study how oxygen molecules in low-Earth 
orbit affect materials that will be used to construct Space 
Station Freedom;

     O Thermal Energy Management (TEMP 2A) experiment to test 
a new cooling method that may be used in future spacecraft;

     O Consortium for Material Development in Space Complex 
Autonomous Payload experiment to study materials processing;

     O Limited Duration Space Environment Candidate Materials 
Exposure experiments will explore materials processing 
methods in weightlessness;

     O An IMAX camera will be in the payload bay to film 
various aspects of the mission for later IMAX productions.

     Atlantis will be commanded by USAF Col. Loren Shriver, 
making his third Shuttle flight.  Marine Corps Major Andy 
Allen will serve as pilot, making his first flight.  Mission 
specialists will include Claude Nicollier, a European Space 
Agency astronaut making his first Shuttle flight; Marsha 
Ivins, making her second Shuttle flight; Jeff Hoffman, making 
his third space flight; and Franklin Chang-Diaz, making his 
third space flight.  Franco Malerba from the Italian Space 
Agency will be the payload specialist aboard Atlantis.

                            -end-

MEDIA SERVICES INFORMATION

NASA Select Television Transmission

     NASA Select television is available on Satcom F-2R, 
Transponder 13, located at 72 degrees west longitude; 
frequency 3960.0 MHz, audio 6.8 MHz.

     The schedule for television transmissions from the 
orbiter and for the mission briefings will be available 
during the mission at Kennedy Space Center, Fla; Marshall 
Space Flight Center, Huntsville; Ames-Dryden Flight Research 
Facility, Edwards, Calif.; Johnson Space Center, Houston, and 
NASA Headquarters, Washington, D.C.  The television schedule 
will be updated to reflect changes dictated by mission 
operations.

     Television schedules also may be obtained by calling 
COMSTOR 713/483-5817.  COMSTOR is a computer data base 
service requiring the use of a telephone modem.  A voice 
update of the television schedule is updated daily at noon 
Eastern time.

Status Reports

     Status reports on countdown and mission progress, on-
orbit activities and landing operations will be produced by 
the appropriate NASA news center.

Briefings

     A mission press briefing schedule will be issued prior 
to launch.  During the mission, change-of-shift briefings by 
the off-going flight director and the science team will occur 
at least once per day.  The updated NASA Select television 
schedule will indicate when mission briefings are planned.

STS-46 QUICK LOOK
 
Launch Date/Site:      July 21, 1992 - Kennedy Space Center, Fla.,
                       Pad 39B
Launch Window:         9:48 a.m. - 12:18 p.m. EDT
Orbiter:               Atlantis (OV-104)
Orbit:                 230 n.m. x 230 n.m. (EURECA deploy)
                       160 n.m. x 160 n.m. (TSS operations)
                       128 n.m. x 128 n.m. (EOIM operations)
Landing Date/Time:     7:57 a.m. EDT July 28, 1992
Primary Landing Site:  Kennedy Space Center, Fla.
Abort Landing Sites:   Return to Launch Site - Kennedy Space Center, Fla.
                       Transoceanic Abort Landing - Banjul, The Gambia
                       Alternates - Ben Guerir, Morocco; Moron, Spain
                       Abort Once Around - Edwards Air Force Base, Calif.
Crew:                  Loren Shriver, Commander
                       Andy Allen, Pilot
                       Claude Nicollier, Mission Specialist 1
                       Marsha Ivins, Mission Specialist 2
                       Jeff Hoffman, Mission Specialist 3
                       Franklin Chang-Diaz, Mission Specialist 4
                       Franco Malerba, Payload Specialist 1
Operational shifts:    Red team -- Ivins, Hoffman, Chang-Diaz
                       Blue team -- Nicollier, Allen, Malerba

Cargo Bay Payloads:  TSS-1 (Tethered Satellite System-1)
                     EURECA-1L (European Retrievable Carrier-1L)
                     EOIM-III/TEMP 2A (Evaluation of Oxygen Integration with
		     Materials/Thermal Management  Processes)
                     CONCAP II (Consortium for Materials Development in Space
		     Complex Autonomous Payload)
                     CONCAP III
                     ICBC (IMAX Cargo Bay Camera)
                     LDCE (Limited Duration Space Environment 
                     Candidate Materials Exposure)

Middeck Payloads:    AMOS (Air Force Maui Optical Site)
                     PHCF (Pituitary Growth Hormone Cell Function)
                     UVPI (Ultraviolet Plume Instrument)

STS-46 SUMMARY OF MAJOR ACTIVITIES

Blue Team Flight Day One:      Red Team Flight Day One
                               Launch
                               Orbit insertion (230 x 230 n.m.)
                               TSS activation
                               RMS checkout
                               TSS deployer checkout
                               EOIM/TEMP-2A activation

Blue Flight Day Two:           Red Flight Day Two:
EURECA deploy                  TEMP-2A operations
EURECA stationkeeping          Tether Optical Phenomenon (TOP)
                                       checkout

Blue Flight Day Three:         Red Flight Day Three:
TOP checkout                   TSS checkout/in-bay operations
Supply water dump nozzle DTO 
TEMP-2A operations 
OMS-3 burn 
OMS-4 burn (160 x 160 n.m.) 
 
Blue Flight Day Four:           Red Flight Day Four:
TSS in-bay operations           TSS deploy
                                TEMP-2A operations

Blue Flight Day Five:           Red Flight Day Five:
TSS on station 1 (12.5 miles)   TSS retrieval to 1.5 miles
                                TSS final retrieval
                                TSS dock

Blue Flight Day Six:            Red Flight Day Six:
TSS safing                      EOIM/TEMP-2A operations
TSS in-bay operations
OMS-5 burn
OMS-6 burn (128 x 128 nm)

Blue Flight Day Seven:          Red Flight Day Seven:
TSS science deactivation        EOIM/TEMP-2A operations
EOIM/TEMP-2A operations         Flight Control Systems 
checkout
                                Reaction Control System 
                                  hot-fire

Blue Flight Day Eight:           Red Flight Day Eight:
                                 Cabin stow
                                 Deorbit preparations
                                 Entry and landing

STS-46 VEHICLE AND PAYLOAD WEIGHTS
 
 
                                                       Pounds

Orbiter (Atlantis) empty, and 3 SSMEs                 151,377

Tethered Satellite -- pallet, support equipment        10,567
 
Tethered Satellite -- satellite, tether                 1,200
 
European Retrievable Carrier                            9,901
 
EURECA Support Equipment                                  414
 
Evaluation of Oxygen Interaction with Materials         2,485
 
CONCAP-II                                                 590
 
CONCAP-III                                                368
 
LDCE                                                    1,125
 
PHDF                                                       69
 
Detailed Supplementary Objectives                          56
 
Detailed Test Objectives                                   42
 
Total Vehicle at SRB Ignition                       4,522,270
 
Orbiter Landing Weight                                208,721

STS-46 Cargo Configuration

STS-46 TRAJECTORY SEQUENCE OF EVENTS
 
                                                RELATIVE
EVENT                          MET              VELOCITY     MACH   ALTITUDE
                               (d:h:m:s)        (fps)               (ft)
 
Launch                         00/00:00:00
 
Begin Roll Maneuver            00/00:00:10         189         .16       797

End Roll Maneuver              00/00:00:15         325         .29     2,260
 
SSME Throttle Down to 80%      00/00:00:26         620         .55     6,937
 
SSME Throttle Down to 67%      00/00:00:53       1,236        1.20    28,748
 
SSME Throttle Up to 104%       00/00:01:02       1,481        1.52    37,307
 
Maximum Dynamic Press          00/00:01:04       1,548        1.61    41,635
(Max Q)

SRB Separation                00/00:02:04        4,221        4.04   152,519
 
Main Engine Cutoff (MECO)     00/00:08:29       24,625       22.74   364,351
 
Zero Thrust                   00/00:08:35       24,624       N/A     363,730
 
ET Separation                 00/00:08:48
 
OMS-2 Burn                    00/00:41:24
 
Landing                       06/22:11:00
 
 
Apogee, Perigee at MECO:          226 x 32 nautical miles 
Apogee, Perigee post-OMS 2:       230 x 230 nautical miles
SPACE SHUTTLE ABORT MODES
 
     Space Shuttle launch abort philosophy aims toward safe 
and intact recovery of the flight crew, orbiter and its 
payload.  Abort modes include:
 
     * Abort-To-Orbit (ATO) -- Partial loss of main engine 
thrust late enough to permit reaching a minimal 105-nautical 
mile orbit with orbital maneuvering system engines.

     * Abort-Once-Around (AOA) -- Earlier main engine 
shutdown with the capability to allow one orbit around before 
landing at either Edwards Air Force Base, Calif., White Sands 
Space Harbor, N.M, or the Shuttle Landing Facility (SLF) at 
the Kennedy Space Center, Fla.
 
     * Trans-Atlantic Abort Landing (TAL) -- Loss of one or 
more main engines midway through powered flight would force a 
landing at either Banjul, The Gambia; Ben Guerir, Morroco; or 
Moron, Spain.
 
    * Return-To-Launch-Site (RTLS) -- Early shutdown of one 
or more engines, without enough energy to reach Ben Guerir, 
would result in a pitch around and thrust back toward KSC 
until within gliding distance of the SLF.
 
     STS-46 contingency landing sites are Edwards Air Force 
Base, the Kennedy Space Center, White Sands Space Harbor, 
Banjul, Ben Guerir and Moron.

STS-46 PRE-LAUNCH PROCESSING

     KSC's processing team began readying the orbiter 
Atlantis for its 12th flight into space following its STS-45 
flight that ended with a landing at KSC on April 2.  Atlantis 
was in the Orbiter Processing Facility (OPF) from April 2 to 
June 4, undergoing post-flight inspections and pre-flight 
testing and inspections.  While in the OPF, technicians 
installed the three main engines.  Engine 2024 is in the No. 
1 position, engine 2012 is in the No. 2 position and engine 
2028 is in the No. 3 position.

     The remote manipulator system was installed on Apr. 28.  
Members of the STS-46 flight crew participated in the Crew 
Equipment Interface Test on May 16.

     Atlantis was towed from the Orbiter Processing Facility 
(OPF) on June 4 to the Vehicle Assembly Building where it was 
mated to its external tank and solid rocket boosters.  
Rollout to Launch Pad 39-B occurred on June 11, 1992.  On 
June 15-16, the Terminal Countdown Demonstration Test with 
the STS-46 flight crew was conducted.

     The Tethered Satellite System (TSS) was processed for 
flight in the Operations and Checkout Building high bay and 
the EURECA payload was processed at the commercial Astrotech 
facility in Titusville, Fla.  The two primary payloads were 
installed in the payload canister at the Vertical Processing 
Facility before they were transferred to the launch pad.

     Payload installation into Atlantis' payload bay was 
accomplished July 8.  Several interface verification tests 
were scheduled between the orbiter and the payload elements.  
A standard 43-hour launch countdown is scheduled to begin 3 
days prior to launch.  During the countdown, the orbiter's 
fuel cell storage tanks will be loaded with fuel and oxidizer 
and all orbiter systems will be prepared for flight.

     About 9 hours before launch, the external tank will be 
filled with its flight load of a half million gallons of 
liquid oxygen and liquid hydrogen propellants.  About 2 and 
one-half hours before liftoff, the flight crew will begin 
taking their assigned seats in the crew cabin.

     Atlantis's end-of-mission landing is planned at Kennedy 
Space Center. Several hours after landing, the vehicle will 
be towed to the Vehicle Assembly Building for a few weeks 
until an OPF bay becomes available. Atlantis will be taken 
out of flight status for several months for a planned 
modification period.  Atlantis' systems will be inspected and 
improved to bring the orbiter up to par with the rest of the 
Shuttle fleet.

     Atlantis's next flight, STS-57, is planned next year 
with the first flight of the Spacehab payload and the 
retrieval of the EURECA payload deployed on the STS-46 
mission.

TETHERED  SATELLITE  SYSTEM (TSS-1)

     An exciting new capability for probing the space 
environment and conducting experiments will be demonstrated 
for the first time when the NASA/Italian Space Agency 
Tethered Satellite System (TSS-1) is deployed during the STS-
46 Space Shuttle flight.

     The Tethered Satellite System is made up of a satellite 
attached to the Shuttle orbiter by a super strong cord that 
will be reeled into space from the Shuttle's cargo bay.  When 
the satellite on its cord, or tether, is deployed to about 12 
miles above the orbiter, TSS-1 will be the longest structure 
ever flown in space.

     For the TSS-1 mission, the tether -- which looks like a 
12-mile-long white bootlace -- will have electrically-
conducting metal strands in its core.

     The conducting tether will generate electrical currents 
at a high voltage by the same basic principle as a standard 
electrical generator -- by converting mechanical energy (the 
Shuttle's more than 17,000-mile-an-hour orbital motion) into 
electrical energy by passing a conductor through a magnetic 
field (the Earth's magnetic field lines).

     TSS-1 scientific instruments, mounted in the Shuttle 
cargo bay, the middeck and on the satellite, will allow 
scientists to examine the electrodynamics of the conducting 
tether system, as well as clarify their understanding of 
physical processes in the ionized plasma of the near-Earth 
space environment.

     The TSS-1 mission will be the first step toward several 
potential future uses for tethers in space now being 
evaluated by scientists and engineers.  One possible 
application is using long conducting tethers to generate 
electrical power for Space Station Freedom or other orbiting 
bodies.

     Conversely, by expending electrical power to reverse the 
current flow into a tether, the system could be placed in an 
"electric motor" mode to generate thrust for orbit 
maintenance.  Tethers also may be used to raise or lower 
spacecraft orbits.  This could be achieved by releasing a 
tethered body from a primary spacecraft, thereby transferring 
momentum (and imparting motion) to the spacecraft.  Another 
potential application is the creation of artificial gravity 
by rotating two or more masses on a tether, much like a set 
of bolas.

     Downward deployment (toward Earth) could place a 
satellite in regions of the atmosphere that have been 
difficult to study because they lie above the range of high-
altitude balloons and below the minimum altitude of free-
flying satellites.  Deploying a tethered satellite downward 
from the Shuttle also could make possible aerodynamic and 
wind tunnel type testing in the region 50 to 75 nautical 
miles above the Earth.

Mission Objectives

     Space-based tethers have been studied theoretically 
since early in this century.  The first practical application 
of a shuttle-based tether was developed by Dr. Mario Grossi, 
Smithsonian Institutin, in the early 1970s.  Professor 
Guiseppe Colombo, University of Padova, Italy, subsequently 
proved the dynamic feasibility of the tether concept and 
suggested various uses.  More recently, the projected 
performance of such systems has been modeled extensively on 
computers.

     In 1984, the growing interest in tethered system 
experiments resulted in the signing of an agreement between 
NASA and the Italian Space Agency (Agenzia Spaziale Italiana 
- ASI) to jointly pursue the definition and development of a 
Tethered Satellite System to fly aboard the Space Shuttle.  
Scientific investigations (including hardware experiments) 
were selected in 1985 in response to a joint NASA/ASI 
announcement of opportunity.

     The TSS-1 mission will be the first time such a large, 
electrodynamic tethered system has ever been flown.  In many 
respects, the mission is like the first test flight of a new 
airplane:  the lessons learned will improve both scientific 
theory and operations for future tether missions.

     The mission objectives are to evaluate the capability 
for safely deploying, controlling and retrieving a tethered 
satellite; to validate predictions of the dynamic forces at 
work in a tethered satellite system; to conduct exploratory 
electrodynamic science investigations; and to demonstrate the 
capability of the system to serve as a facility for research 
in geophysical and space physics.

     Since the dynamics of the Tethered Satellite System are 
complex and only can be tested fully in orbit, it is 
impossible to predict before the mission exactly how the 
system will perform in the space environment.  In particular, 
retrieval and recapture present the greatest uncertainties.

     Though tether system dynamics have been extensively 
tested and simulated, it could be that actual dynamics will 
differ somewhat from predictions.  The complexity of a widely 
separated, multi-component system and the forces created by 
the flow of current through the system are other variables 
that will affect the system's performance.

Responsibilities

     Responsibility for Tethered Satellite System activities 
within NASA is divided between the Marshall Space Flight 
Center, Huntsville, Ala., and the Johnson Space Center, 
Houston.  Marshall has the development and integration 
responsibility.  Marshall also is responsible for developing 
and executing the TSS-1 science mission, and science teams 
for each of the 12 experiments work under that center's 
direction.  During the mission, Johnson will be responsible 
for the operation of the TSS-1 payload.  This includes 
deployment and retrieval of the satellite by the crew as well 
as controlling the satellite's motion in orbit and monitoring 
the state of the 

       Satellite (stowed for launch) and Deployer on Carriers

Spacelab pallet, the deployer and the satellite.  Marshall 
will furnish real-time engineering support for the TSS-1 
system components and tether dynamics.  The ASI 
responsibility for the TSS system is the development of the 
tethered satellite, the Italian onboard experiments and the 
Core equipment.  In addition, ASI is providing satellite/Core 
equipment engineering support during the mission.  All remote 
commanding of science instruments aboard the satellite and 
deployer will be executed by a Marshall payload operations 
control cadre stationed at Johnson for the mission.

Tethered Satellite System Hardware

     The Tethered Satellite System has five major components:  
the deployer system, the tether, the satellite, the carriers 
on which the system is mounted and the science instruments.  
Under the 1984 memorandum of understanding, the Italian Space 
Agency agreed to provide the satellite and NASA agreed to 
furnish the deployer system and tether.  The carriers are 
specially adapted Spacelab equipment, and the science 
instruments were developed by various universities, 
government agencies and companies in the United States and 
Italy.

Carriers

     TSS-1 hardware rides on two carriers in the Shuttle 
cargo bay.  The deployer is mounted on a Spacelab Enhanced 
Multiplexer-Demultiplexer pallet, a general-purpose 
unpressurized platform equipped to provide structural support 
to the deployer, as well as temperature control, power 
distribution and command and data transmission capabilities.  
The second carrier is the Mission Peculiar Equipment Support 
Structure, an inverted A-frame truss located immediately aft 
of the enhanced pallet.  The support structure, also 
Spacelab-provided, holds science support equipment and two of 
the TSS-1 science experiments.

Deployer

     The deployer system includes the structure supporting 
the satellite, the deployment boom, which initially lifts the 
satellite away from the orbiter, the tether reel, a system 
that distributes power to the satellite before deployment and 
a data acquisition and control assembly.

     Cables woven through the structure provide power and 
data links to the satellite until it is readied for release.  
When the cables are disconnected after checkout, the 
satellite operates on its internal battery power. 

     The boom, with the satellite resting atop it, is housed 
in a canister in the lower section of the satellite support 
structure.  As deployment begins, the boom will unfold and 
extend slowly out of the turning canister, like a bolt being 
forced upward by a rotating nut.  As the upward part of the 
canister rotates, horizontal cross members (fiberglass 
battens similar to those that give strength to sails) are 
unfolded from their bent-in-half positions to hold the 
vertical members (longerons) erect.  Additional strength is 
provided by diagonal tension cables.  The process is reversed 
for retrieval.  When it is fully extended, the 40-foot boom 
resembles a short broadcasting tower.

          Orbiter with deployed tether and satellite

Tether cutaway

     The tether reel mechanism regulates the tether's length, 
tension and rate of deployment -- critical factors for tether 
control.  Designed to hold up to 68 miles of tether, the reel 
is 3.3 feet in diameter and 3.9 feet long.  The reel is 
equipped with a "level-wind" mechanism to assure uniform 
winding on the reel, a brake assembly for control of the 
tether and a drive motor.  The mechanism is capable of 
letting out the tether at up to about 10 miles per hour.  
However, for the TSS-1 mission, the tether will be released 
at a much slower rate.

Tether

     The tether's length and electrical properties affect all 
aspects of tethered operations.  For the TSS-1 mission, the 
tether will be reeled out to an altitude about 12 miles above 
the Shuttle, making the TSS-1/orbiter combination 100 times 
longer than any previous spacecraft.  It will create a large 
current system in the ionosphere, similar to natural currents 
in the Earth's polar regions associated with the aurora 
borealis.  When the tether's current is pulsed by electron 
accelerators, it becomes the longest and lowest frequency 
antenna ever placed in orbit.  Also, for the first time, 
scientists can measure the level of charge or electric 
potential acquired by a spacecraft as a result of its motion 
through the Earth's magnetic field lines.  All these 
capabilities are directly related to the structure of the 
bootlace-thick tether, a conducting cord designed to anchor a 
satellite miles above the orbiter.

     The TSS-1 tether is 13.7 miles long.  When deployed, it 
is expected to develop a 5,000-volt electrical potential and 
carry a maximum current of 1 ampere.  At its center is the 
conductor, a 10-strand copper bundle wrapped around a Nomex 
(nylon fiber) core.  The wire is insulated with a layer of 
Teflon, then strength is provided with a layer of braided 
Kevlar -- a tough, light synthetic fiber also used for making 
bulletproof vests.  An outer braid of Nomex protects the 
tether from atomic oxygen.  The cable is about 0.1 inch in 
diameter.

Satellite

     Developed by the Italian Space Agency, the spherical 
satellite is a little more than 5 feet in diameter and is 
latched atop the deployer's satellite support structure.  The 
six latches are released when boom extension is initiated.  
After the satellite is extended some 40 feet above the 
orbiter atop the boom, tether unreeling will begin.

     The satellite is divided into two hemispheres and a 
centered propulsion module.  The payload module (the upper 
half of the sphere opposite the tether) houses satellite-
based science instruments.  Support systems for power 
distribution, data handling, telemetry and navigational 
equipment are housed in the service module or lower half.  
Eight aluminum-alloy panels, covered with electrically 
conductive paint, developed at the Marshall Space Flight 
Center, form the outer skin of the satellite.  Doors in the 
panels provide access for servicing batteries; windows for 
sun, Earth and charged-particle sensors; and connectors for 
cables from the deployer.

     A fixed boom for mounting science instruments extends 
some 39 inches from the equator of the satellite sphere.  A 
short mast opposite the boom carries an S-band antenna for 
sending data and receiving commands.  For the TSS-1 mission, 
the satellite is outfitted with two additional instrument-
mounting booms on opposite sides of the upper sphere.  The 
booms may be extended up to 8 feet from the body of the 
satellite, allowing instruments to sample the surrounding 
environment, then be retrieved inside the payload module 
before the satellite is reeled back to the Shuttle.

     Attitude of the tethered satellite is controlled by its 
auxiliary propulsion module, while the satellite motion is 
controlled by the deployer's tether reel and motor.  The 
module also initiates, maintains and controls satellite spin 
at up to 0.7 revolution per minute on command from the 
Shuttle.  One set of thrusters near the tether attachment can 
provide extra tension on the tether, another can be used to 
reduce or eliminate pendulum-type motions in the satellite, 
and a third will be used to spin and de-spin the satellite.  
A pressurized tank containing gaseous nitrogen for the 
thrusters is located in the center of the sphere.

                  Satellite with booms extended

TSS Spacecraft

TETHERED SATELLITE SYSTEM-1 FLIGHT OPERATIONS

     The responsibility for flying the tethered satellite, 
controlling the stability of the satellite, tether and 
Atlantis, lies with the flight controllers in the Mission 
Control Center at the Johnson Space Center, Houston.
 
     The primary flight control positions contributing to the 
flight of the Tethered Satellite System (TSS) are the 
Guidance and Procedures (GPO) area and the Payloads area.  
GPO officers will oversee the dynamic phases of deployment 
and retrieval of the satellite and are responsible for 
determining the correct course of action to manage any tether 
dynamics.  To compute corrective actions, the GPO officers 
will combine data from their workstations with inputs from 
several investigative teams.  

     The Payloads area will oversee control of the satellite 
systems, the operation of the tether deployer and all other 
TSS systems.  Payloads also serves as the liaison between 
Mission Control Center and the science investigators, sending 
all real-time commands for science operations to the 
satellite.  Atlantis' crew will control the deployer reel and 
the satellite thrusters from onboard the spacecraft.
 
Deploy Operations
 
     The satellite will be deployed from Atlantis when the 
cargo bay is facing away from Earth, with the tail slanted 
upward and nose pitched down.  A 39-foot long boom, with the 
satellite at its end, is raised out of the cargo bay to 
provide clearance between the satellite and Shuttle during 
deploy and retrieval operations.  The orientation of the 
payload bay will result in the tethered satellite initially 
deployed upward but at an angle of about 40 degrees behind 
Atlantis' path.
 
     Using the tether reel's electric motors to unwind the 
tether, an electric motor at the end of the boom to pull the 
tether off of the reel and a thruster on the satellite that 
pushes the satellite away from Atlantis, the satellite will 
be moved away from the Shuttle. The deployment will begin 
extremely slowly, with the satellite, after 1 hour has 
elapsed since the tether was first unwound, moving away from 
Atlantis at about one-half mile per hour. The initial 
movement of the satellite away from the boom will be at less 
than two-hundredths of 1 mile per hour.  The speed of deploy 
will continue to increase, peaking after 1 and a half hours 
from the initial movement to almost 4 miles per hour.  

     At this point, when the satellite is slightly less than 
1 mile from Atlantis, the rate of deployment will begin 
slowing briefly, a maneuver that is planned to reduce the 40-
degree angle to 5 degrees and put the satellite in the same 
plane almost directly overhead of Atlantis by the time that 
about 3 miles of tether has been unwound.
 
     When the satellite is 3.7 miles from Atlantis, 2 and 
one-half hours after the start of deployment, a one-quarter 
of a revolution-per-minute spin will be imparted to it via 
its attitude control system thrusters.  The slight spin is 
needed for science operations with the satellite.
 
     After this, the speed of deployment will again be 
increased gradually, climbing to a peak separation from 
Atlantis of almost 5 mph about 4 hours into the deployment 
when the satellite is about 9 miles distant.  From this 
point, the speed with which the tether is fed out will 
gradually decrease through the rest of the procedure, coming 
to a stop almost 5 and half hours after the initial movement, 
when the satellite is almost 12.5 miles from Atlantis.  Just 
prior to the satellite arriving on station at 12.5 miles 
distant, the quarter-revolution spin will be stopped briefly 
to measure tether dynamics and then, a seven-tenths of a 
revolution-per-minute spin will be imparted to it.  At full 
deploy, the tension on the tether or the pull from the 
satellite is predicted to be equivalent to about 10 pounds of 
force.
 
     The tether, in total, is 13.7 miles long, allowing an 
extra 1.2 miles of spare tether that is not planned to be 
unwound during the mission.
 
Dynamics Functional Objectives
 
     During the deploy of TSS, several tests will be 
conducted to explore control and dynamics of a tethered 
satellite.  Models of deployment have shown that the longer 
the tether becomes, the more stable the system becomes.  The 
dynamics and control tests to be conducted during deploy also 
will aid in preparing for retrieval of the satellite and 
serve to verify the ability to control the satellite during 
that operation.  During retrieval, it is expected that the 
stability of the system will decrease as the tether is 
shortened, just opposite the way stability increased as the 
tether was lengthened during deploy.
 
     The dynamics tests involve maintaining a constant 
tension on the tether and correcting any of several possible 
disturbances to it.  Possible disturbances include:  a 
bobbing motion, also called a plumb bob, where the satellite 
bounces slightly on the tether causing it to alternately 
slacken and tighten; a vibration of the tether, called a 
libration, resulting in a clock-pendulum type movement of 
tether and satellite; a pendulous motion of the satellite or 
a rolling and pitching action by the satellite at the end of 
the tether; and a lateral string mode disturbance, a motion 
where the satellite and Shuttle are stable, but the tether is 
moving back and forth in a "skip rope" motion.  All of these 
disturbances may occur naturally and are not unexpected.

     The first test objectives will be performed before the 
satellite reaches 200 yards from Atlantis and will involve 
small firings of Atlantis' steering jets to test the 
disturbances these may impart to the tether and satellite.  
The crew will test three different methods of damping the 
libration (clock pendulum) motion expected to be created in 
the tether and the pendulous (rolling and pitching) motion 
expected in the satellite.  First, using visual contact with 
the satellite, to manually stabilize it from onboard the 
Shuttle by remotely firing TSS's attitude thrusters.  Second, 
using the telemetry information from the satellite to 
manually fire the satellite's attitude thrusters.  Third, 
using an automatic attitude control system for the satellite 
via the Shuttle's flight control computers to automatically 
fire the TSS thrusters and stabilize the system.
 
     Another test will be performed when the satellite is 
about 2.5 miles from Atlantis.  Atlantis' autopilot will be 
adjusted to allow the Shuttle to wobble by as much as 10 
degrees in any direction before steering jets automatically 
fire to maintain Atlantis' orientation.  The 10-degree 
deadband will be used to judge any disturbances that may be 
imparted to the satellite if a looser attitude control is 
maintained by Atlantis.  The standard deadband, or degree of 
wobble, set in Shuttle autopilot for the tethered satellite 
operations is 2 degrees of wobble.  Tests using the wider 
deadband will allow the crew and flight controllers to 
measure the amount of motion the satellite and tether impart 
to Atlantis.

     Dampening of the various motions expected to occur in 
the tether and satellite will be accomplished while at 12.5 
miles using electrical current flow through the tether.  
During retrieval, test objectives will be met using a 
combination of the Shuttle's steering jets, a built-in 
dampening system at the end of the deploy boom and the 
satellite's steering jets.
 
Tether Retrieval Operations
 
     Tether retrieval will occur more slowly than deployment.  
The rate of tether retrieval, the closing rate between 
Atlantis and the satellite, will build after 5 hours since 
first movement to a peak rate of about 3 miles per hour.  At 
that point, when the satellite is about 4 and a half miles 
from Atlantis, the rate of retrieval will gradually decrease, 
coming to a halt 10 hours after start of retrieval operations 
when the satellite is 1.5 miles from Atlantis.
 
     The satellite will remain at 1.5 miles from Atlantis for 
about 5 hours of science operations before the final 
retrieval begins.  Final retrieval is expected to take about 
2 hours.  A peak rate of closing between Atlantis and the 
satellite of about 1.5 miles per hour will be attained just 
after the final retrieval begins, and the closing rate will 
decrease gradually through the remainder of the operation.  
The closing rate at the time the satellite is docked to the 
cradle at the end of the deployer boom is planned to be less 
than one-tenth of 1 mile per hour.

     If the safety of the orbiter becomes a concern, the 
tether will be cut and the satellite released or the 
satellite and boom jettisoned.

TSS-1 SCIENCE OPERATIONS

     Speeding through the magnetized ionospheric plasma at 
almost 5 miles per second, a 12-mile-long conducting tethered 
system should create a variety of very interesting plasma-
electrodynamic phenomena.  These are expected to provide 
unique experimental capabilities, including the ability to 
collect an electrical charge and drive a large current system 
within the ionosphere; generate high voltages (on the order 
of 5 kilovolts) across the tether at full deployment; control 
the satellite's electrical potential and its plasma sheath 
(the layer of charged particles created around the 
satellite); and generate low-frequency electrostatic and 
electromagnetic waves.  It is believed that these 
capabilities can be used to conduct controlled experimental 
studies of phenomena and processes that occur naturally in 
plasmas throughout the solar system, including Earth's 
magnetosphere.

     A necessary first step toward these studies -- and the 
primary science goal of the TSS-1 mission -- is to 
characterize the electrodynamic behavior of the satellite-
tether-orbiter system.  Of particular interest is the 
interaction of the system with the charged particles and 
electric and magnetic fields in the ionosphere.  

     A circuit must be closed to produce an electrical 
current.  For example, in a simple circuit involving a 
battery and a light bulb, current travels down one wire from 
the battery to the bulb, through the bulb and back to the 
battery via another wire completing the circuit.  Only when 
the the circuit is complete will the bulb illuminate.  The 
conductive outer skin of the satellite collects free 
electrons from the space plasma, and the induced voltage 
causes the electrons to flow down the conductive tether to 
the Shuttle.  Then, they will be ejected back into space by 
electron generator (Core equipment).

     Scientists expect the electrons to travel along magnetic 
field lines in the ionosphere to complete the loop.  TSS-1 
investigators will use a series of interdependent experiments 
conducted with the electron guns and tether current-control 
hardware, along with a set of diagnostic instruments, to 
assess the nature of the external current loop within the 
ionosphere and the processes by which current closure occurs 
at the satellite and the orbiter.

Science Operations

     The TSS-1 mission is comprised of 11 scientific 
investigations selected jointly by NASA and the Italian Space 
Agency.  In addition, the U.S. Air Force's Phillips 
Laboratory, by agreement, is providing an experimental 
investigation.  Seven investigations provide equipment that 
either stimulates or monitors the tether system and its 
environment.  Two investigations will use ground-based 
instruments to measure electromagnetic emissions from the 
Tethered Satellite System as it passes overhead, and three 
investigations were selected to provide theoretical support 
in the areas of dynamics and electrodynamics.

     Most of the TSS-1 experiments require measurements of 
essentially the same set of physical parameters, with 
instrumentation from each investigation providing different 
parts of the total set.  While some instruments measure 
magnetic fields, others record particle energies and 
densities, and still others map electric fields.  A complete 
set of data on plasma and field conditions is required to 
provide an accurate understanding of the space environment 
and its interaction with the tether system.  TSS-1 science 
investigations, therefore, are interdependent.  They must 
share information and operations to achieve their objectives.  
In fact, these investigations may be considered to be 
different parts of a single complex experiment.

     The TSS-1 principal and associate investigators and 
their support teams will be located in a special Science 
Operations Center at the Mission Control Center in Houston.  
During the tethered satellite portion of the STS-46 flight, 
all 12 team leaders will be positioned at a conference table 
in the operations center.  Science data will be available to 
the entire group, giving them an integrated "picture" of 
conditions observed by all the instruments.  Together, they 
will assess performance of the experiment objectives.  
Commands to change any instrument mode that affects the 
overall data set must be approved by the group, because such 
a change could impact the overall science return from the 
mission.  Requests for adjustments will be relayed by the 
mission scientist, the group's leader, to the science 
operations director for implementation.

     The primary scientific data will be taken during the 
approximately 10.5-hour phase (called "on-station 1") when 
the satellite is extended to the maximum distance above the 
Shuttle. Secondary science measurements will be taken prior 
to and during deployment, during "on-station 1," and as the 
satellite is reeled back to the orbiter.  However, after 
accomplishment of the primary science objectives, tether 
dynamic control takes priority over further science data 
gathering.

     Science activities during the TSS-1 mission will be 
directed by the science principal investigator team and 
implemented by a payload cadre made up primarily of Marshall 
Space Flight Center employees and their contractors.  Science 
support teams for each of the 12 experiments will monitor the 
science hardware status.  From the Science Operations Center 
at Mission Control, the principal investigator team will be 
able to evaluate the quality of data obtained, replan science 
activities as needed and direct adjustments to the 
instruments.  The cadre will be led by a science operations 
director, who will work closely with the mission scientist, 
the mission manager and Mission Control's payloads officer to 
coordinate science activities.

     During the mission, most activities not carried out by 
the crew will be controlled by command sequences, or timeline 
files, written prior to the mission and stored in an onboard 
computer.  For maximum flexibility, however, during all TSS 
phases, modifications to these timeline files may be 
uplinked, or commands may be sent in real-time from the 
Science Operations Center to the on-board instruments.

SCIENCE INVESTIGATIONS

TSS Deployer Core Equipment and Satellite Core Equipment 
(DCORE/SCORE)

Principal Investigator:

Dr. Carlo Bonifazi
Italian Space Agency, Rome, Italy

     The Tethered Satellite System Core Equipment controls 
the electrical current flowing between the satellite and the 
orbiter.  It also makes a number of basic electrical and 
physical measurements of the system.

     Mounted on the aft support structure in the Shuttle 
cargo bay, the Deployer Core Equipment features two identical 
electron generators (the prime and the back up) that can each 
eject up to 750 milli-amperes (3/4 amp) of current from the 
system.  A master switch, the electron generator control 
switches, power distribution and electronic control unit, and 
command and data interfaces also are included in the deployer 
core package.  A voltmeter measures tether potential with 
respect to the orbiter structure, and a vacuum gauge measures 
ambient gas pressure to prevent operations if pressure 
conditions might cause electrical arcing.

     Core equipment located on the satellite itself includes 
an ammeter to measure tether current collected on the skin of 
the TSS-1 satellite and an accelerometer-gyro three exes 
packages to measure satellite motion and attitude.

Research on Orbital Plasma Electrodynamics (ROPE)

Principal Investigator:

Dr. Nobie Stone
NASA Marshall Space Flight Center, Huntsville, Ala.

     This experiment studies behavior of ambient charged 
particles in the ionosphere and ionized neutral particles 
around the satellite under a variety of conditions.  
Comparisons of readings from its instruments should allow 
scientists to determine where the particles come from that 
make up the tether current as well as the distribution and 
flow of charged particles in the space immediately 
surrounding the satellite.

     The Differential Ion Flux Probe, mounted on the end of 
the satellite's fixed boom, measures the energy, temperature, 
density and direction of ambient ions that flow around the 
satellite as well as neutral particles that have been ionized 
in its plasma sheath and accelerated outward by the sheath's 
electric field.

     The Soft Particle Energy Spectrometer is actually five 
electrostatic analyzers -- three mounted at different 
locations on the surface of the satellite itself, and the 
other two mounted with the Differential Ion Flux Probe on the 
boom.  Taken together, measurements from the two boom-mounted 
sensors can be used to determine the electrical potential of 
the sheath of ionized plasma surrounding the satellite.  The 
three satellite-mounted sensors will measure geometric 
distribution of the current to the satellite's surface.

Research on Electrodynamic Tether Effects (RETE)

Principal Investigator:

Dr. Marino Dobrowolny
Italian National Research Council, Rome, Italy

     This experiment measures the electrical potential in the 
plasma sheath around the satellite and identifies waves 
excited by the satellite and tether system.  The instruments 
are located in two canisters at the end of the satellite's 
extendible booms.  As the satellite spins, the booms are 
extended, and the sensors sweep the plasma around the entire 
circumference of the spacecraft.  To produce a profile of the 
plasma sheath, measurements of direct-current potential and 
electron currents are made both while the boom is fully 
extended and as it is being extended or retracted.  The same 
measurements, taken at a fixed distance from the spinning 
satellite, produce a map of the angular structure of the 
sheath.

Magnetic Field Experiment for TSS Missions (TEMAG)

Principal Investigator:

Prof. Franco Mariani
Second University of Rome, Italy

     The primary goal of this investigation is to map the 
levels and fluctuations in magnetic fields around the 
satellite.  Two magnetometers -- very accurate devices for 
measuring such fields -- are located on the fixed boom of the 
satellite, one at its end and the other at its midpoint.  
Comparing measurements from the two magnetometers allows 
real-time estimates to be made of unwanted disturbances to 
the magnetic fields produced by the presence of satellite 
batteries, power systems, gyros, motors, relays and other 
magnetic material.  After the mission, the variable effects 
of switching satellite subsystems on and off, of thruster 
firings and of other operations that introduce magnetic 
disturbances will be modeled on the ground, so these 
satellite effects can be subtracted from measurements of the 
ambient magnetic fields in space.

Shuttle Electrodynamic Tether System (SETS)

Principal Investigator:

Dr. Peter Banks
University of Michigan, Ann Arbor

     This investigation studies the ability of the tethered 
satellite to collect electrons by determining current and 
voltage of the tethered system and measuring the resistance 
to current flow in the tether itself.  It also explores how 
tether current can be controlled by the emission of electrons 
at the orbiter end of the system and characterizes the charge 
the orbiter acquires as the tether system produces power, 
broadcasts low-frequency radio waves and creates 
instabilities in the surrounding plasma.

     The hardware is located on the support structure in the 
orbiter cargo bay.  In addition to three instruments to 
characterize the orbiter's charge, the experiment includes a 
fast-pulse electron accelerator used to help neutralize the 
orbiter's charge.  It is located close to the core electron 
gun and aligned so beams from both are parallel.  The fast-
pulse accelerator acts as a current modulator, emitting 
electron beams in recognizable patterns to stimulate wave 
activity over a wide range of frequencies.  The beams can be 
pulsed with on/off times on the order of 100 nanoseconds.

Shuttle Potential and Return Electron Experiment (SPREE)

Associate Investigators:

Dr. Dave Hardy and Capt. Marilyn Oberhardt
Dept. of the Air Force, Phillips Laboratory, Bedford, Mass.

     Also located on the support structure, this experiment 
will measure populations of charged particles around the 
orbiter.  Measurements will be made prior to deployment to 
assess ambient space conditions as well as during active TSS-
1 operations.  The measurements will determine the level of 
orbiter charging with respect to the ambient space plasma, 
characterize the particles returning to the orbiter as a 
result of TSS-1 electron beam ejections and investigate local 
wave-particle interactions produced by TSS-1 operations.  
Such information is important in determining how the Tethered 
Satellite System current is generated, and how it is affected 
by return currents to the orbiter.  The experiment uses two 
sets of two nested electrostatic analyzers each, which rotate 
at approximately 1 revolution per minute, sampling the 
electrons and ions in and around the Shuttle's cargo bay.

Tether Optical Phenomena Experiment (TOP)

Associate Investigator:

Dr. Stephen Mende
Lockheed, Palo Alto Research Laboratory, Palo Alto, Calif.

     This experiment uses a hand-held, low-light-level TV 
camera system operated by the crew, to provide visual data to 
allow scientists to answer a variety of questions about 
tether dynamics and optical effects generated by TSS-1.  The 
imaging system will operate in four configurations:  
filtered, interferometer, spectrographic and filtered with a 
telephoto lens.  In particular, the experiment will image the 
high voltage plasma sheath surrounding the satellite when it 
is reeled back toward the orbiter near the end of the 
retrieval stage of the mission.

Investigation of Electromagnetic Emissions for Electrodynamic 
Tether (EMET)

Principal Investigator:

Dr. Robert Estes
Smithsonian Astrophysical Observatory, Cambridge, Mass.

Observations at the Earth's Surface of Electromagnetic 
Emission by TSS (OESEE)

Principal Investigator:

Dr. Giorgio Tacconi, University of Genoa, Italy

     The main goal of these experiments is to determine how 
well the Tethered Satellite System can broadcast from space.  
Ground-based radio transmissions, especially below 15 kilohertz,
are inefficient since most of the power supplied 
to the antenna -- large portions of which are buried -- is 
absorbed by the ground.  Since the Tethered Satellite System 
operates in the ionosphere, it should radiate waves more 
efficiently.  Magnetometers at several locations in a chain 
of worldwide geomagnetic observatories and extremely low-
fequency receivers at the Arecibo Radio Telescope facility, 
Puerto Rico, and other sites around the world, will try to 
measure the emissions produced and track direction of the 
waves when electron accelerators pulse tether current over 
specific land reference points.  An Italian ocean surface and 
ocean bottom observational facility also provides remote 
measurements for TSS-1 emissions.

The Investigation and Measurement of Dynamic Noise in the TSS 
(IMDN)

Principal Investigator:

Dr. Gordon Gullahorn
Smithsonian Astrophysical Observatory, Cambridge, Mass.

Theoretical and Experimental Investigation of TSS Dynamics 
(TEID)

Principal Investigator:

Prof. Silvio Bergamaschi
Institute of Applied Mechanics, Padua University, Padua, 
Italy

     These two investigations will analyze data from a 
variety of instruments to examine Tethered Satellite System 
dynamics or oscillations over a wide range of frequencies.  
Primary instruments will be accelerometers and gyros on board 
the satellite, but tether tension and length measurements and 
magnetic field measurements also will be used.  The dynamics 
will be observed in real-time at the Science Operations 
Center and later, subjected to detailed post-flight analysis.  
Basic theoretical models and simulations of tether movement 
will be verified, extended or corrected as required.  Then 
they can be used confidently in the design of future systems.

Theory and Modeling in Support of Tethered Satellite 
Applications (TMST)

Principal Investigator:

Dr. Adam Drobot
Science Applications International Corp., McLean, Va.

     This investigation provides theoretical electro-dynamic 
support for the mission.  Numerical models were developed of 
anticipated current and voltage characteristics, plasma 
sheaths around the satellite and the orbiter and of the 
system's response to the operation of the electron 
accelerators.  These models tell investigators monitoring the 
experiments from the ground what patterns they should expect 
to see in the data.

THE TSS-1 TEAM

     Within NASA, the Tethered Satellite System program is 
directed by the Office of Space Flight and the Office of 
Space Science and Applications.  The Space Systems Projects 
Office at the Marshall Space Flight Center, Huntsville, Ala., 
has responsibility for project management and overall systems 
engineering.  Experiment hardware systems were designed and 
developed by the U.S. and Italy.  Responsibility for 
integration of all hardware, including experiment systems on 
the MPESS pallet, is assigned to the project manager at the 
Marshall center.  The Kennedy Space Center, Florida, is 
responsible for launch-processing and launch of the TSS-1 
payload.  The Johnson Space Center, Houston, has 
responsibility for TSS-1/STS integration and mission 
operations.

     R.J. Howard of the Office of Space Science and 
Applications, NASA Headquarters, Washington, D.C., is the 
TSS-1 Science Payload Program Manager.  The TSS Program 
Manager is Tom Stuart of the Office of Space Flight, NASA 
Headquarters.  Billy Nunley is NASA Project Manager and TSS-1 
Mission Manager at the Marshall Space Flight Center.  Dr. 
Nobie Stone, also of Marshall, is the NASA TSS-1 Mission 
Scientist, the TSS Project Scientist and Co-chairman of the 
Investigator Working Group.  

     For the Italian Space Agency responsible for the 
satellite, Core equipment and Italian experiments development 
and for the science integration into the satellite, Dr. 
Gianfranco Manarini is Program Manager for TSS-1, while the 
Program Scientist is Dr. F. Mariani.  Dr. Marino Dobrowolny 
is the Project Scientist for the Italian Space Agency, and 
Co-chairman of the investigator group.  Dr. Maurizio Candidi 
is the Mission Scientist for the Italian Space Agency.

     Martin Marietta, Denver, Colo., developed the tether and 
control system deployer for NASA.  Alenia Spazio in Turin, 
Italy, developed the satellite and the Core equipment for the 
Italian Space Agency.

TSS-1 SCIENCE INVESTIGATIONS

            Title                    Institution (Nation)

Research on Electrodynamic           CNR or Italian National
Tether Effects                       Research Council (Italy) 

Research on Orbital Plasma           NASA/MSFC (U.S.)
Electrodynamics

Shuttle Electrodynamic Tether Sys.  University of Michigan 
(U.S.)

Magnetic Field Experiments          Second University of Rome 
for TSS Missions                    (Italy)

Theoretical & Experimental          Univ. of Padua (Italy)
Investigation of TSS Dynamics

Theory & Modeling in Support         SAIC (U.S.)
of Tethered Satellite

Investigation of Electromagnetic     Smithsonian 
Astrophysical
Emissions for Electrodynamic         Observatory (U.S.)
Tether

Investigation and Measurement of     Smithsonian 
Astrophysical 
Dynamic Noise in TSS                 Observatory (U.S.)

Observation on Earth's Surface of    Univ. of Genoa (Italy)
Electromagnetic Emissions by TSS

Deployer Core Equipment and Satellite   ASI (Italy)
Core Equipment

Tether Optical Phenomena Experiment  Lockheed (U.S.)

Shuttle Potential & Return           Dept. of the Air Force
Electron Experiment                  Phillips Laboratory 
(U.S.)

EUROPEAN RETRIEVABLE CARRIER (EURECA)

     The European Space Agency's (ESA) EURECA will be 
launched by the Space Shuttle and deployed at an altitude of 
425 km.  It will ascend, using its own propulsion, to its 
operational orbit of 515 km.  After 6 to 9 months in orbit, 
it will descend to the lower orbit where it will be retrieved 
by another orbiter and brought back to Earth.  It will 
refurbished and equipped for the next mission.
 
     The first mission (EURECA-1) primarily will be devoted 
to research in the fields of material and life sciences and 
radiobiology, all of which require a controlled microgravity 
environment.  The selected microgravity experiments will be 
carried out in seven facilities.  The remaining payload 
comprises space science and technology.
 
     During the first mission, EURECA's residual carrier 
accelerations will not exceed 10-5g.  The platform's altitude 
and orbit control system makes use of magnetic torquers 
augmented by cold gas thrusters to keep disturbance levels 
below 0.3 Nm during the operational phase.
 
Physical characteristics
  
o  Launch mass                                        4491 kg
o  Electrical power solar array                         5000w
o  Continuous power to EURECA experiments...............1000w
o  Launch configuration           dia:  4.5m,  length:  2.54m
o  Volume                                               40.3m
o  Solar array extended                             20m x 3.5
 
User friendly
 
     Considerable efforts have been made during the design 
and development phases to ensure that EURECA is a "user 
friendly" system.  As is the case for Spacelab, EURECA has 
standardized structural attachments, power and data 
interfaces.  Unlike Spacelab, however, EURECA has a 
decentralized payload control concept.  Most of the onboard 
facilities have their own data handling device so that 
investigators can control the internal operations of their 
equipment directly.  This approach provides more flexibility 
as well as economical advantages.

Operations

     EURECA is directly attached to the Shuttle cargo bay by 
means of a three-point latching system.  The spacecraft has 
been designed with a minimum length and a close-to-optimum 
length-to-mass ratio, thus helping to keep down launch and 
retrieval costs.

     All EURECA operations will be controlled by ESA's Space 
Operations Centre (ESOC) in Darmstadt, Germany.  During the 
deployment and retrieval operations, ESOC will function as a 
Remote Payload Operations Control 

EURECA-1L

Centre to NASA's Mission Control Center, Houston, and the 
orbiter will be used as a relay station for all the commands.  
In case of unexpected communication gaps during this period, 
the orbiter crew has a back-up command capability for 
essential functions.  

     Throughout the operational phase, ESOC will control 
EURECA through two ground stations at Maspalomas, ---, and 
Kourou, French Guiana.  EURECA will be in contact with its 
ground stations for a relatively short period each day.  When 
it is out of contact, or "invisible", its systems operate 
with a high degree of autonomy, performing failure detection, 
isolation and recovery activities to safeguard ongoing 
experimental processes.
 
     An experimental advanced data relay system, the Inter-
orbit Communication package, is included in the first 
payload.  This package will communicate with the European 
Olympus Communication Satellite to demonstrate the possible 
improvements for future communications with data relay 
satellites.  As such a system will significantly enhance 
realtime data coverage, it is planned for use on subsequent 
EURECA missions to provide an operational service via future 
European data relay satellites.

EURECA Retrievable Carrier
 
Structure
 
     The EURECA structure is made of high strength carbon-
fibre struts and titanium nadal points joined together to 
form a framework of cubic elements.  This provides relatively 
low thermal distortions, allows high alignment accuracy and 
simple analytical verification, and is easy to assemble and 
maintain.  Larger assemblies are attached to the nadal 
points.  Instruments weighing less than 100 kg are assembled 
on standard equipment support panels similar to those on a 
Spacelab pallet.

Thermal Control
 
     Thermal control for EURECA combines active and passive 
heat transfer and radiation systems.  Active transfer, 
required for payload facilities which generated more heat, is 
achieve by means of a freon cooling loop which dissipates the 
thermal load through two radiators into space.  The passive 
system makes use of multilayer insulation blankets combined 
with electrical heaters.  During nominal operations, the 
thermal control subsystem rejects a maximum heat load of 
about 2300 w.
 
Electrical Power
 
     The electrical power subsystem generates, stores, 
conditions and distributes power to all the spacecraft 
subsystems and to the payload.  The deployable and retracable 
solar arrays, with a combined raw power output of some 5000 w 
together with four 40 amp-hour (Ah) nickel-cadmium batteries, 
provide the payload with a continuous power of 1000 w, 
nominally at 28 volts, with peak power capabilities of up to 
1500 w for several minutes.  While EURECA is in the cargo 
bay, electric power is provided by the Shuttle to ensure that 
mission critical equipment is maintained within its 
temperature limits.

 Attitude and Orbit Control

     A modular attitude and orbit control subsystem (AOCS) is 
used for attitude determination and spacecraft orientation 
and stabilization during all flight operations and orbit 
control manoeuvres.  The AOCS has been designed for maximum 
autonomy.  It will ensure that all mission requirements are 
met even in case of severe on-board failures, including non-
availability of the on-board data handling subsystem for up 
to 48 hours.

     An orbit transfer assembly, consisting of two redundant 
sets of four thrusters, is used to boost EURECA to its 
operation attitude at 515 km and to return it to its 
retrieval orbit at about 300 km.  The amount of onboard 
propellant hydrazine is sufficient for the spacecraft to fly 
different mission profiles depending on its nominal mission 
duration which may be anywhere between 6 and 9 months.
 
     EURECA is three-axis stabilized by means of a magnetic 
torque assembly together with a nitrogen reaction control 
assembly (RCA).  This specific combination of actuators was 
selected because its' control accelerations are well below 
the microgravity constraints of the spacecraft.  The RCA cold 
gas system can be used during deployment and retrieval 
operations without creating any hazards for the Shuttle.

Communications and Data Handling
 
     EURECA remote control and autonomous operations are 
carried out by means of the data handling subsystem (DHS) 
supported by the telemetry and telecommand subsystems which 
provide the link to and from the ground segment.  Through the 
DHS, instructions are stored and executed, telemetry data is 
stored and transmitted, and the spacecraft and its payload 
are controlled when EURECA is no longer "visible" from the 
ground station.

EURECA SCIENCE

Solution Growth Facility (SGF)
 
Principal Investigator:
 
J.C. Legros
Universit Libre de Bruxelles, Brussels, Belgium
 
     The Solution Growth Facility (SGF) is a multi-user 
facility dedicated to the growth of monocrystals from 
solution, consisting of a set of four reactors and their 
associated control system.
 
     Three of the reactors will be used for the solution 
growth of crystals.  These reactors have a central buffer 
chamber containing solvent and two reservoirs containing 
reactant solutions.  The reservoirs are connected to the 
buffer chamber by valves which allow the solutions to diffuse 
into the solvent and hence, to crystallize.
 
     The fourth reactor is divided into twenty individual 
sample tubes which contain different samples of binary 
organic mixtures and aqueous electrolyte solutions.  This 
reactor is devoted to the measurement of the Soret 
coefficient, that is, the ratio of thermal to isothermal 
diffusion coefficient.
 
     The SGF has been developed under ESA contract by Laben 
and their subcontractors Contraves and Terma.

Protein Crystallization Facility (PCF)
 
Principal Investigator:
 
W. Littke
Chemisches Laboratorium, Universitt Freiburg, Freiburg, 
Germany
 
     The Protein Crystallization Facility (PCF) is a multi-
user solution growth facility for protein crystallization in 
space.  The object of the experiments is the growth of 
single, defect-free protein crystals of high purity and of a 
size sufficient to determine their molecular structure by x-
ray diffraction.  This typically requires crystal sizes in 
the order of a few tenths of a millimeter.
 
     The PCF contains twelve reactor vessels, one for each 
experiment.  Each reactor, which is provided with an 
individually controlled temperature environment, has four 
chambers -- one containing the protein, one containing a 
buffer solution and two filled with salt solutions.  When the 
reactors have reached their operating temperatures, one of 
the salt solution chambers, the protein chamber and the 
buffer solution chamber are opened.  Salt molecules diffuse 
into the buffer chamber causing the protein solution to 
crystalize.  At the end of the mission the second salt 
solution chamber is activated to increase the salt 
concentration.  This stabilizes the crystals and prevents 
them from dissolving when individual temperature control for 
the experiments ceases and the reactors are maintained at a 
common storage temperature.
 
     One particular feature of the PCF is that the 
crystallization process can be observed from the ground by 
means of a video system.
 
     The PCF has been developed under ESA contract by MBB 
Deutsche Aerospace and their subcontractors Officine Galileo 
and Reusser.

Exobiology And Radiation Assembly (ERA)
 
Principal Investigator:
 
H. Bcker
Institut fr Flugmedizin Abteilung Biophysik, German 
Aerospace Research Establishment (DLR), Cologne, Germany
 
     The Exobiology and Radiation Assembly (ERA) is a multi-
user life science facility for experiments on the biological 
effects of space radiation.  Our knowledge of the interaction 
of cosmic ray particles with biological matter, the synergism 
of space vacuum and solar UV, and the spectral effectiveness 
of solar UV on viability should be improved as a result of 
experiments carried out in the ERA.
 
     The ERA consists of deployable and fixed experiment 
trays and a number of cylindrical stacks, known as Biostacks, 
containing biological objects such as spores, seeds or eggs 
alternated with radiation and track detectors.  An electronic 
service module also is included in the facility.  The 
deployable trays carry biological specimens which are exposed 
to the different components of the space radiation 
environment for predetermined periods of time.  The duration 
of exposure is controlled by means of shutters and the type 
of radiation is selected by the use of optical bandpass 
filters.
 
The ERA has been developed under ESA contract by Sira Ltd..

Multi-Furnace Assembly (MFA)
 
Principal Investigator:
 
A. Passerone
Ist. di Chimica Fisica Applicata dei Materiali, National 
Research Council (CNR), Genova, Italy
 
     The Multi-Furnace Assembly (MFA) is a multi-user 
facility dedicated to material science experiments.  It is a 
modular facility with a set of common system interfaces which 
incorporates twelve furnaces of three different types, giving 
temperatures of up to 1400xC.  Some of the furnaces are 
provided by the investigators on the basis of design 
recommendations made by ESA.  The remainder are derived from 
furnaces flown on other missions, including some from 
sounding rocket flights.  These are being used on EURECA 
after the necessary modifications and additional 
qualification.  The experiments are performed sequentially 
with only one furnace operating at any one time.
 
     The MFA has been developed under ESA contract by 
Deutsche Aerospace, ERNO Raumfahrttechnik and their 
subcontractors SAAB, Aeritalia, INTA and Bell Telephone.

Automatic Mirror Furnace (AMF)
 
Principal Investigator:
 
K.W. Benz
Kristallographisches Institut, Universitt Freiburg, 
Freiburg, Germany
 
     The Automatic Mirror Furnace (AMF) is an optical 
radiation furnace designed for the growth of single, uniform 
crystals from the liquid or vapor phases, using the traveling 
heater or Bridgman methods.
 
     The principal component of the furnace is an ellipsoidal 
mirror.  The experimental material is placed at the lower 
ring focus of the mirror and heated by radiation from a 300 w 
halogen lamp positioned at the upper focus.  Temperatures of 
up to 1200xC can be achieved, depending on the requirements 
of individual samples.  Seven lamps are available and up to 
23 samples can be processed in the furnace.
 
     As the crystal grows, the sample holder is withdrawn 
from the mirror assembly at crystallization speed, typically 
2 mm/day, to keep the growth site aligned with the furnace 
focus.  The sample also is rotated while in the furnace.
 
     The AMF is the first of a new generation of crystal 
growth facilities equipped with sample and lamp exchange 
mechanisms.  Fully automatic operations can be conducted in 
space during long microgravity missions on free flying 
carriers.  During a 6 month mission, about 20 different 
crystal growth experiments can be performed.
 
     The AMF has been developed under ESA contract by Dornier 
Deutsche Aerospace and their subcontractors Laben, ORS and 
SEP.

Surface Forces Adhesion Instrument (SFA)
 
Principal Investigator:
 
G. Poletti
Universita di Milano, Milan, Italy
 
     The Surface Forces Adhesion instrument (SFA) has been 
designed to study the dependence of surface forces and 
interface energies on physical and chemical-physical 
parameters such as surface topography, surface cleanliness, 
temperature and the deformation properties of the contacting 
bodies.  The SFA experiment aims at refining current 
understanding of adhesion-related phenomena, such as friction 
and wear, cold welding techniques in a microgravity 
environment and solid body positioning by means of adhesion.
 
     Very high vacuum dynamic measurements must be performed 
in microgravity conditions because of the extreme difficulty 
experienced on Earth in controlling the physical parameters 
involved.  As a typical example, the interface energy of a 
metallic sphere of 1 g mass contacting a pane target would be 
of the order of 10-3 erg. corresponding to a potential 
gravitational energy related to a displacement of 10-5 mm.  
In the same experiment performed on the EURECA platform, in a 
10 to 100,000 times lower gravity environment, this energy 
corresponds to a displacement of 1 mm, thus considerably 
improving measurements and reducing error margins.
 
     The SFA instrument has been funded by the Scientific 
Committee of the Italian Space Agency (ASI) and developed by 
the University of Milan and their subcontractors 
Centrotechnica, Control Systems and Rial.

High Precision Thermostat Instrument (HPT)
 
Principal Investigator:
 
G. Findenegg
Ruhr Universitt Bochum, Bochum, Germany
 
     Basic physics phenomena around the critical point of 
fluids are not, as yet, fully understood.  Measurements in a 
microgravity environment, made during the German mission D-1, 
seem to be at variance with the expected results.  Further 
investigations of critical phenomena under microgravity 
conditions are of very high scientific value.
 
     The High Precision Thermostat (HPT) is an instrument 
designed for long term experiments requiring microgravity 
conditions and high precision temperature measurement and 
control.  Typical experiments are "caloric", "critical point" 
or "phase transition" experiments, such as the "Adsorption" 
experiment designed for the EURECA mission.
 
     This experiment will study the adsorption of Sulphur 
Hexafluoride (SF6), close to its critical point (Tc=45.55xC, 
pc=0.737 g/cm3) on graphitised carbon.  A new volumetric 
technique will be used for the measurements of the adsorption 
coefficient at various temperatures along the critical 
isochore starting from the reference temperature in the one-
phase region (60x) and approaching the critical temperature.  
The results will be compared with 1g measurements and 
theoretical predictions.
 
     The HPT has been developed under DLR contract by 
Deutsche Aerospace, ERNO Raumfahrttechnik and their 
subcontractor Kayser-Threde GmbH.

Solar Constant And Variability Instrument (SOVA)
 
Principal Investigator:
 
D. Crommelynck
Institut Royal Mtorologique de Belgique (IRMB), Brussels, 
Belgium
 
     The Solar Constant and Variability Instrument (SOVA) is 
designed to investigate the solar constant, its variability 
and its spectral distribution, and measure:

  o  fluctuations of the total and spectral solar irradiance 
within periods of a few minutes up to several hours and with 
a resolution of 10-6 to determine the pressure and gravity 
modes of the solar oscillations which carry information on 
the internal structure of the sun;

  o  short term variations of the total and spectral solar 
irradiance within time scales ranging from hours to few 
months and with a resolution of 10-5 for the study of energy 
redistribution in the solar convection zone.  These 
variations appear to be associated with solar activities (sun 
spots);

  o  long term variations of the solar luminosity in the time 
scale of years (solar cycles) by measuring the absolute solar 
irradiance with an accuracy of better than 0.1 percent and by 
comparing it with previous and future measurements on board 
Spacelab and other space vehicles.  This is of importance for 
the understanding of solar cycles and is a basic reference 
for climatic research.
 
     The SOVA instrument has been developed by the IRMB, by 
the Physikalisch-Meteorologishces Observatorium World 
Radiation Center (PMOD/WRC) Davos, Switzerland, and by the 
Space Science Department (SSD) of the European Space Agency 
(ESA-ESTEC), Noordwijk, The Netherlands.

Solar Spectrum Instrument (SOSP)
 
Principal Investigator:
 
G. Thuillier
Service d'Aeronomie du Centre National de Recherche 
Scientifique (CNRS), Verrieres le Buisson, France
 
     The Solar Spectrum Instrument (SOSP) has been designed 
for the study of solar physics and the solar-terrestrial 
relationship in aeronomy and climatology.  It measures the 
absolute solar irradiance and its variations in the spectral 
range from 170 to 3200 nm, with an expected accuracy of 1 
percent in the visible and infrared ranges and 5 percent in 
the ultraviolet range.

     Changes in the solar irradiance mainly relate to the 
short-term solar variations that have been observed since 
1981 by the Solar Maximum spacecraft, the variations related 
to the 27-day solar rotation period and the long-term 
variations related to the 11-year sun cycles.  While the 
short term variations can be measured during one single 
EURECA flight mission, two or three missions are needed to 
assess the long term variations.
 
     SOSP has been developed by the Service d'Aeronomie of 
the CNRS, the Institut d'Aeronomie Spatiale de Belgique 
(IASB), the Landessternwarte Koenigstuhl and the Hamburger 
Sternwarte.

Occultation Radiometer Instrument (ORA)
 
Principal Investigator:
 
E. Arijs
Belgisch Instituut voor Ruimte Aeronomie (BIRA), Brussels, 
Belgium
 
     The Occultation Radiometer instrument (ORA) is designed 
to measure aerosols and trace gas densities in the Earth's 
mesosphere and stratosphere.  The attenuation of the various 
spectral components of the solar radiation as it passes 
through the Earth's atmosphere enables vertical abundance 
profiles for ozone, nitrogen dioxide, water vapor, carbon 
dioxide and background and volcanic aerosols to be determined 
for altitudes between 20 and 100 km.
 
     The ORA instrument has been developed by the Institut 
d'Aeronomie Spatiale, and the Clarendon Laboratory of the 
University of Oxford.

Wide Angle Telescope (WATCH)
 
Principal Investigator:
 
N. Lund
Danish Space Research Institute, Lyngby, Denmark
 
     The Wide Angle Telescope (WATCH) is designed to detect 
celestial gamma and x-ray sources with photon energies in the 
range 5 to 200 keV and determine the position of the source.
 
     The major objective of WATCH is the detection and 
localization of gamma-ray bursts and hard x-ray transients.  
Persistent x-ray sources also can be observed.
 
     Cosmic gamma-ray bursts are one of the most extreme 
examples of the variability of the appearance of the x-ray 
sky.  They rise and decay within seconds, but during their 
life they outshine the combined flux from all other sources 
of celestial x- and gamma rays by factors of up to a 
thousand.
 
     Less conspicuous, but more predictable are the x-ray 
novae which flare regularly, typically with intervals of a 
few years.  In the extragalactic sky, the "active galactic 
nuclei" show apparently are random fluctuations in their x-
ray luminosity over periods of days or weeks.
 
     WATCH will detect and locate these events.  The data 
from the experiment can be used to provide light curves and 
energy for the sources.  The data also may be searched for 
regularities in the time variations related to orbital 
movement or rotation or for spectral features that yield 

information about the source.  Additionally, other, more 
powerful sky observation instruments can be alerted to the 
presence of objects that WATCH has detected as being in an 
unusual state of activity.
 
WATCH has been developed by the Danish Space Research 
Institute.

Timeband Capture Cell Experiment (TICCE)
 
Principal Investigator:
 
J.A.M. McDonnell
Unit for Space Science, Physics Laboratory
University of Kent, United Kingdom
 
     The Timeband Capture Cell Experiment (TICCE) is an 
instrument designed for the study of the microparticle 
population in near-Earth space -- typically Earth debris, 
meteoroids and cometary dust.  The TICCE will capture micron 
dimensioned particles with velocities in excess of 3 km/s and 
store the debris for retrieval and post-mission analysis.
 
     Particles detected by the instrument pass through a 
front foil and into a debris collection substrate positioned 
100 nm behind the foil.  Each perforation in the foil will 
have a corresponding debris site on the substrate.  The foil 
will be moved in 50 discrete steps during the six month 
mission, and the phase shift between the debris site and the 
perforation will enable the arrival timeband of the particle 
to be determined.  Between 200 and 300 particles are expected 
to impact the instrument during the mission.  Ambiguities in 
the correlation of foil perforations and debris sites will 
probably occur for only a few of the impacts.
 
     Elemental analysis of the impact sites will be 
performed, using dispersive x-ray techniques, once the 
instrument has returned to Earth.
 
     TICCE has been developed by the University of Kent.  Its 
structural support has been sponsored by ESA and 
subcontracted to SABCA under a Deutsche Aerospace ERNO 
Raumfahrttechnik contract.
Radio Frequency Ionization Thruster Assembly (RITA)
 
Principal Investigator:
 
H. Bassner
MBB Deutsche Aerospace, Munich, Germany
 
     The Radio Frequency Ionization Thruster Assembly (RITA) 
is designed to evaluate the use of electric propulsion in 
space and to gain operational experience before endorsing its 
use for advanced spacecraft technologies.
 
     The space missions now being planned - which are both 
more complex and of longer duration - call for increased 
amounts of propellant for their propulsion systems which, in 
turn, leads to an increase in the overall spacecraft mass to 
the detriment of the scientific or applications payload.  
Considerable savings can be made in this respect by the use 
of ion propulsion systems, wherein a gas is ionized and the 
positive ions are them accelerated by an electric field.  In 
order to avoid spacecraft charging, the resulting ion beam is 
then neutralized by an electron emitting device, the 
neutralizer.  The exhaust velocities obtained in this way are 
about an order of magnitude higher than those of chemical 
propulsion systems.
 
     RITA has been developed under ESA and German Ministry 
for Research and Technology (BMFT) contract by Deutsche
Aerospace ERNO Raumfahrttechnik.

Inter-Orbit Communication (IOC)
 
R. Tribes
French Space Agency (CNES) Project Manager, CNES-IOC
Toulouse, France
 
N. Neale
ESA Project Manager, ESTEC-CD
Noordwijk, The Netherlands
 
     The Inter-Orbit Communication (IOC) instrument is a 
technological experiment designed to provide a pre-
operational inflight test and demonstration of the main 
functions, services and equipment typical of those required 
for a data relay system, namely:

o  bi-directional, end-to-end data transmission between the 
user spacecraft and a dedicated ground station via a relay 
satellite in the 20/30 GHz frequency band;

o  tracking of a data relay satellite;

o  tracking of a user spacecraft;

o  ranging services for orbit determination of a user 
spacecraft via a relay satellite.

     In this case, the EURECA platform is the user spacecraft 
and the ESA communications satellite Olympus the relay 
satellite.  One of the Olympus steerable spot beam antennas 
will be pointed towards the IOC on EURECA and the other 
towards the IOC ground station.  The IOC instrument is 
provided with a mobile directional antenna to track Olympus.

     The IOC has been developed under ESA contract by CNES 
and their subcontractors Alocatel Espace, Marconi Space 
Systems, Laben, Matra Espace, Sener, Alcatel Bel, AEG-
Telefunken, ETCA, TEX, MDS and COMDEV.

Advanced Solar Gallium Arsenide Array (ASGA)
 
Principal Investigator:
 
C. Flores
CISE SPA, Segrate, Italy
 
     The Advanced Solar Gallium Arsenide Array (ASGA) will 
provide valuable information on the performance of gallium 
arsenide (GaAs) solar arrays and on the effects of the low 
Earth orbit environment on their components.  These solar 
cells, already being used in a trial form to power the Soviet 
MIR space station, are expected to form the backbone of the 
next generation of compact, high power-to-weight ratio 
European solar energy generators.
 
     The most significant environmental hazards encountered 
arise from isotropic proton bombardment in the South Atlantic 
Anomaly, high frequency thermal cycling fatigue of solar cell 
interconnections and the recently discovered atomic oxygen 
erosion of solar array materials.  Although a certain amount 
of knowledge may be gained from laboratory experiments, the 
crucial confirmation of the fidelity of the GaAs solar array 
designs awaits the results of flight experiments.
 
     The project has been sponsored by the Italian Space 
Agency (ASI) and developed by CISE with its subcontractor, 
Carlo Gavazzi Space.  The planar solar module has been 
assembled by FIAR.  The miniature Cassegranian concentrator 
components have been developed in collaboration with the 
Royal Aircraft Establishments and Pilkington Space 
Technology.

     EURECA has been developed under ESA contract by Deutsche 
Aerospace, ERNO Raumfahrttechnik, (Germany), and their 
subcontractors Sener, (England), AIT, (Italy), SABCA, 
(Belgium), AEG, (Germany), Fokker, (The Netherlands), Matra, 
(France), Deutsche Aerospace, ERNO Raumfahrttechnik, 
(Germany), SNIA-BPD, (Italy), BTM, (Belgium), and Laben, 
(Italy).

F. Schwan - Industrial Project Manager
Deutsche Aerospace, ERNO Raumfahrttechnik, Bremen, Germany
W. Nellessen - ESA Project Manager
ESTEC MR, Noordwijk, The Netherlands

EVALUATION OF OXYGEN INTERACTION WITH MATERIALS/TWO PHASE 
MOUNTING PLATE EXPERIMENT (EOIM-III/TEMP 2A-3)

EOIM

     The Evaluation of Atomic Oxygen Interactions with 
Materials (EOIM) payload will obtain accurate reaction rate 
measurements of the interaction of space station materials 
with atomic oxygen.  It also will measure the local Space 
Shuttle environment, ambient atmosphere and interactions 
between the two.  This will improve the understanding of the 
effect of the Shuttle environment on Shuttle and payload 
operations and will update current models of atmospheric 
composition.  EOIM also will assess the effects of 
environmental and material parameters on reaction rates.

     To make these measurements, EOIM will use an ion-neutral 
mass spectrometer to obtain aeronomy measurements and to 
study atom-surface interaction products.  The package also 
provides a mass spectrometer rotating carousel system 
containing RmodeledS polymers for mechanistic studies.  EOIM 
also will study the effects of mechanical stress on erosion 
rates of advanced composites and the effects of temperature 
on reaction rates of disk specimens and thin films.  Energy 
accommodations on surfaces and surface-atom emission 
characteristics concerning surface recession will be measured 
using passive scatterometers.  The payload also will assess 
solar ultraviolet radiation reaction rates.

     The environment monitor package will be activated pre-
launch, while the remainder of the payload will be activated 
after payload bay door opening.  Experiment measurements will 
be made throughout the flight, and the package will be 
powered down during de-orbit preparations.

TEMP

     The Two Phase Mounting Plate Experiment (TEMP 2A-3) has 
two-phase mounting plates, an ammonia reservoir, mechanical 
pumps, a flowmeter, radiator and valves, and avionics 
subsystems.  The TEMP is a two-phase thermal control system 
that utilizes vaporization to transport large amounts of heat 
over large distances.  The technology being tested by TEMP is 
needed to meet the increased thermal control requirements of 
space station.  The TEMP experiment will be the first 
demonstration of a mechanically pumped two-phase ammonia 
thermal control system in microgravity.  It also will 
evaluate a propulsion-type fluid management reservoir in a 
two-phase ammonia system, measure pressure drops in a two-
phase fluid line, evaluate the performance of a two-phase 
cold plate design and measure heat transfer coefficients in a 
two-phase boiler experiment.  EOIM-III/TEMP 2A-3 are 
integrated together on a MPESS payload carrier in the payload 
bay.

EOIM 111/TEMP 2A

CONSORTIUM FOR MATERIALS DEVELOPMENT IN SPACE COMPLEX 
AUTONOMOUS PAYLOAD (CONCAP)

     The Consortium for Materials Development in Space 
Complex Autonomous Payload (CONCAP) is sponsored by NASA's 
Office of Commercial Programs (OCP).  On STS-46, two CONCAP 
payloads (CONCAP-II and -III) will be flown in 5-foot 
cylindrical GAS (Get Away Special) canisters.
 
     CONCAP-II is designed to study the changes that 
materials undergo in low-Earth orbit.  This payload involves 
two types of experiments to study the surface reactions 
resulting from exposing materials to the atomic oxygen flow 
experienced by the Space Shuttle in orbit.  The atomic oxygen 
flux level also will be measured and recorded.  The first 
experiment will expose different types of high temperature 
superconducting thin films to the 5 electron volt atomic 
oxygen flux to achieve improved properties.  Additional novel 
aspects of this experiment are that a subset of the materials 
samples will be heated to 320 degrees Celsius (the highest 
temperature used in space), and that the material resistance 
change of 24 samples will be measured on-orbit.
 
     For the second CONCAP-II experiment, the surface of 
different passive materials will be exposed (at ambient and 
elevated temperatures) to hyperthermal oxygen flow.  This 
experiment will enable enhanced prediction of materials 
degradation on spacecraft and solar power systems.  In 
addition, this experiment will test oxidation-resistant 
coatings and the production of surfaces for commercial use, 
development of new materials based on energetic molecular 
beam processing and development of an accurate data base on 
materials reaction rates in orbit.
 
     CONCAP-III is designed to measure and record absolute 
accelerations (microgravity levels) in one experiment and to 
electroplate pure nickel metal and record the conditions 
(temperature, voltage and current) during this process in 
another experiment.  Items inside the orbiter experience 
changes in acceleration when various forces are applied to 
the orbiter, including thruster firing, crew motion and for 
STS-46, tethered satellite operations.  By measuring absolute 
accelerations, CONCAP-III can compare the measured force that 
the orbiter undergoes during satellite operations with 
theoretical calculations.  Also, during accelerations 
measurements, CONCAP-III can gather accurate acceleration 
data during the electroplating experiments. 

     The second CONCAP-III experiment is an electroplating 
experiment using pure nickel metal.  This experiment will 
obtain samples for analysis as part of a study of 
microgravity effects on electroplating.  Materials 
electroplated in low gravity tend to have different 
structures than materials electroplated on Earth.  
Electroplating will be performed before and during the 
tethered satellite deployment to study the differences that 
occur for different levels of accelerations.
 
     The CONCAP-II and -III experiments are managed and 
developed by the Consortium for Materials Development in 
Space, a NASA Center for the Commercial Development of Space 
at the University of Alabama in Huntsville (UAH).  Payload 
integration and flight hardware management is handled by 
NASA's Goddard Space Flight Center, Greenbelt, Md.
 
     Dr. John C. Gregory and Jan A. Bijvoet of UAH are 
Principal investigator and payload manager, respectively, for 
CONCAP-II.  For CONCAP-III, principal investigator for the 
acceleration experiment is Bijvoet, principal investigator 
for the electrodeposition (electroplating) is Dr. Clyde 
Riley, also of UAH, and payload manager is George W. Maybee 
of McDonnell Douglas Space Systems Co., Huntsville, Ala.  

LIMITED DURATION SPACE ENVIRONMENT CANDIDATE MATERIALS 
EXPOSURE (LDCE)

     The first of the Limited Duration Space Environment 
Candidate Materials Exposure (LDCE) payload series is 
sponsored by NASA's Office of Commercial Programs (OCP).  The 
LDCE project on STS-46 represents an opportunity to evaluate 
candidate space structure materials in low-Earth orbit.
 
     The objective of the project is to provide engineering 
and scientific information to those involved in materials 
selection and development for space systems and structures.  
By exposing such materials to representative space 
environments, an analytical model of the performance of these 
materials in a space environment can be obtained.
 
     The LDCE payload consists of three separate experiments, 
LDCE-1, -2 and -3, which will examine the reaction of 356 
candidate materials to at least 40 hours exposure in low-
Earth orbit.  LDCE-1 and -2 will be housed in GAS (Get Away 
Special) canisters with motorized door assemblies.  LDCE-3 
will be located on the top of the GAS canister used for 
CONCAP-III.  Each experiment has a 19.65-inch diameter 
support disc with a 15.34-inch diameter section which 
contains the candidate materials.  The support disc for LDCE-
3 will be continually exposed during the mission, whereas 
LDCE-1 and -2 will be exposed only when the GAS canisters' 
doors are opened by a crew member.  Other than opening and 
closing the doors, LDCE payload operations are completely 
passive.  The doors will be open once the Shuttle achieves 
orbit and will be closed periodically during Shuttle 
operations, such as water dumps, jet firings and changes in 
attitude.
 
     Two primary commercial goals of the flight project are 
to identify environmentally-stable structural materials to 
support continued humanization and commercialization of the 
space frontier and to establish a technology base to service 
growing interest in space materials environmental stability.

LDCE

     The LDCE payload is managed and developed by the Center 
for Materials on Space Structures, a NASA Center for the 
Commercial Development of Space at Case Western Reserve 
University (CWRU) in Cleveland.  Dr. John F. Wallace, 
Director of Space Flight Programs at CWRU, is lead 
Investigator.  Dawn Davis, also of CWRU, is program manager.

PITUITARY GROWTH HORMONE CELL FUNCTION (PHCF)

Principal Investigator:

Dr. W.C. Hymer
The Pennsylvania State University, University Park, Pa.

	The Pituitary Growth Hormone Cell Function (PHCF) 
experiment is a middeck-locker rodent cell culture 
experiment.  It continues the study of the influence of 
microgravity on growth hormone secreted by cells isolated 
from the brain's anterior pituitary gland.

	PHCF is designed to study whether the growth hormone-
producing cells of the pituitary gland have an internal 
gravity sensor responsible for the decreased hormone release 
observed following space flight.  This hormone plays an 
important role in muscle metabolism and immune-cell function 
as well as in the growth of children.  Growth hormone 
production decreases with age.  The decline is thought to 
play an important role in the aging process.

	The decreased production of biologically active growth 
hormone seen during space flight could be a factor in the 
loss of muscle and bone strength and the decreased immune 
response observed in astronauts following space flight.  If 
the two are linked, PHCF might identify mechanisms for 
providing countermeasures for astronauts on long space 
missions.  It also may lead to increased understanding of the 
processes underlying human muscle degeneration as people age 
on Earth. 

	The PHCF experiment uses cultures of living rat 
pituitary cells.  These preparations will be placed in 165 
culture vials carried on the Shuttle's middeck in an 
incubator.  After the flight, the cells will be cultured and 
their growth hormone output assayed.

IMAX CARGO BAY CAMERA (ICBC)

     The IMAX Cargo Bay Camera (ICBC) is aboard STS-46 as 
part of NASA's continuing collaboration with the Smithsonian 
Institution in the production of films using the IMAX system.  
This system, developed by IMAX Corp., Toronto, Canada, uses 
specially-designed 70 mm film cameras and projectors to 
produce very high definition motion picture images which, 
accompanied by six channel high fidelity sound, are displayed 
on screens up to ten times the size used in conventional 
motion picture theaters.

PHCF

ICBC

     "The Dream is Alive" and "Blue Planet," earlier products 
of this collaboration, have been enjoyed by millions of 
people around the world.  On this flight, the camera will be 
used primarily to cover the EURECA and Tether Satellite 
operations, plus Earth scenes as circumstances permit.  The 
footage will be used in a new film dealing with our use of 
space to gain new knowledge of the universe and the future of 
mankind in space.  Production of these films is sponsored by 
the Lockheed Corporation.

AIR FORCE MAUI OPTICAL SYSTEM (AMOS)

     The Air Force Maui Optical System (AMOS) is an 
electrical-optical facility located on the Hawaiian island of 
Maui.  The facility tracks the orbiter as it flies over the 
area and records signatures from thruster firings, water 
dumps or the phenomena of shuttle glow, a well-documented 
glowing effect around the shuttle caused by the interaction 
of atomic oxygen with the spacecraft.

     The information obtained is used to calibrate the 
infrared and optical sensors at the facility.  No hardware 
onboard the shuttle is needed for the system.

ULTRAVIOLET PLUME EXPERIMENT

     The Ultraviolet Plume Experiment (UVPI) is an instrument 
on the Low-Power Atmospheric Compensation Experiment (LACE) 
satellite launched by the Strategic Defense Initiative 
Organization in February 1990.  LACE is in a 43-degree 
inclination orbit of 290 n.m.  Imagery of Columbia's engine 
firings or attitude control system firings will be taken on a 
non-interference basis by the UVPI whenever an opportunity is 
available during the STS-46 mission.

STS-46 CREW BIOGRAPHIES

     Loren J. Shriver, 47, Col., USAF, will serve as 
commander of STS-46.  Selected as an astronaut in January 
1978, Shriver considers Paton, Iowa, his hometown and will be 
making his third space flight.
 
     Shriver graduated from Paton Consolidated High School, 
received a bachelor's in aeronautical engineering from the 
Air Force Academy and received a master's in aeronautical 
engineering from Purdue University.
 
     Shriver was pilot of STS-51C in January 1985, a 
Department of Defense-dedicated shuttle flight.  He next flew 
as commander of STS-31 in April 1990, the mission that 
deployed the Hubble Space Telescope.  Shriver has logged more 
than 194 hours in space.
 
     Andrew M. Allen, 36, Major, USMC, will serve as pilot.  
Selected as an astronaut in June 1987, Allen was born in 
Philadephia, Pa., and will be making his first space flight.
 
     Allen graduated from Archbishop Wood High School in 
Warminster, Pa., in 1973 and received a bachelor's in 
mechanical engineering from Villanova University in 1977.
 
     Allen was commissioned in the Marine Corps in 1977.  
Following flight school, he was assigned to fly the F-4 
Phantom at the Marine Corps Air Station in Beaufort, S.C.  He 
graduated from the Navy Test Pilot School in 1987 and was a 
test pilot under instruction at the time of his selection by 
NASA.  He has logged more than 3,000 flying hours in more 
than 30 different types of aircraft.
 
     Claude Nicollier, 47, will be Mission Specialist 1 
(MS1).  Under an agreement between the European Space Agency 
and NASA, he was selected as an astronaut in 1980.  Nicollier 
was born in Vevey, Switzerland, and will be making his first 
space flight.
 
     Nicollier graduated from Gymnase de Lausanne, Lausanne, 
Switzerland, received a bachelor's in physics from the 
University of Lausanne and received a master's in 
astrophysics from the University of Geneva.
 
     In 1976, he accepted a fellowship at ESA's Space Science 
Dept., working as a research scientist in various airborne 
infrared astronomy programs.  In 1978, he was selected by ESA 
as one of three payload specialist candidates for the 
Spacelab-1 shuttle mission, training at NASA for 2 years as 
an alternate.  In 1980, he began mission specialist training.  
Nicollier graduated from the Empire Test Pilot School, 
Boscombe Down, England, in 1988, and holds a commission as 
Captain in the Swiss Air Force.  He has logged more than 
4,300 hours flying time, 2,700 in jet aircraft.

      Marsha S. Ivins, 41, will be Mission Specialist 2 
(MS2).  Selected as an astronaut in 1984, Ivins was born in 
Baltimore, Md., and will be making her second space flight.
 
     Ivins graduated from Nether Providence High School, 
Wallingford, Pa., and received a bachelor's in aerospace 
engineering from the University of Colorado.
 
     Ivins joined NASA shortly after graduation and was 
employed at the Johnson Space Center as an engineer in the 
Crew Station Design Branch until 1980.  she was assigned as a 
flight simulation engineer aboard the Shuttle Training 
Aircraft and served as co-pilot of the NASA administrative 
aircraft.
 
     She first flew on STS-32 in January 1990, a mission that 
retrieved the Long Duration Exposure Facility (LDEF).  She 
has logged more than 261 hours in space.

     Jeffrey A. Hoffman, 47, will be Mission Specialist 3 
(MS3) and serve as Payload Commander.  Selected as an 
astronaut in January 1978, Hoffman considers Scarsdale, N.Y., 
his hometown and will be making his third space flight.
 
     Hoffman graduated from Scarsdale High School, received a 
bachelor's in astronomy from Amherst College, received a 
doctorate in astrophysics from Harvard University and 
received a master's in materials science from Rice 
University.
 
     Hoffman first flew on STS-51D in April 1985, a mission 
during which he performed a spacewalk in an attempt to rescue 
a malfunctioning satellite.  He next flew on STS-35 in 
December 1990, a mission carrying the ASTRO-1 astronomy 
laboratory.
 
     Franklin R. Chang-Diaz will be Mission Specialist 4 
(MS4).  Selected as an astronaut in May 1980, Chang-Diaz was 
born in San Jose, Costa Rica, and will be making his third 
space flight.
 
     Chang-Diaz graduated from Colegio De La Salle in San 
Jose and from Hartford High School, Hartford, Ct.; received a 
bachelor's in mechanical engineering from the University of 
Connecticut and received a doctorate in applied physics from 
the Massachusetts Institute of Technology.
 
     Chang-Diaz first flew on STS-61C in January 1986, a 
mission that deployed the SATCOM KU satellite.  He next flew 
on STS-34 in October 1989, the mission that deployed the 
Galileo spacecraft to explore Jupiter.  Chang-Diaz has logged 
more than 265 hours in space.
 
     Franco Malerba, 46, will serve as Payload Specialist 1 
(PS1).  An Italian Space Agency payload specialist, Malerba 
was born in Genoa, Italy, and will be making his first space 
flight.
 
     Malerba graduated from Maturita classica in 1965, 
received a bachelor's degree in electrical engineering from 
the University of Genova in 1970 and received a doctorate in 
physics from the University of Genova in 1974.
 
     From 1978-1980, he was a staff member of the ESA Space 
Science Dept., working on the development and testing of an 
experiment in space plasma physics carried aboard the first 
shuttle Spacelab flight.  From 1980-1989, he has held various 
technical and management positions with Digital Equipment 
Corp. in Europe, most recently as senior telecommunications 
consultant at the European Technical Center in France.  
Malerba is a founding member of the Italian Space Society.

MISSION MANAGEMENT FOR STS-46

NASA HEADQUARTERS, WASHINGTON, D.C.

Office of Space Flight
Jeremiah W. Pearson III - Associate Administrator
Brian O'Connor - Deputy Associate Administrator
Tom Utsman - Director, Space Shuttle
Thomas D. Stewart TSS-1 Program Manager

Office of Space Science
Dr. Lennard A. Fisk - Associate Administrator, Office of 
Space Science
	 and Applications
Alphonso V. Diaz -  Deputy Associate Administrator, Office of 
Space 
	Science and Applications
George Withbroe - Director, Space Physics Division
R.J. Howard - TSS-1 Science Payload Program Manager

Office of Commercial Programs
John G. Mannix  - Assistant Administrator
Richard H. Ott - Director, Commercial Development Division
Garland C. Misener - Chief, Flight Requirements and
   Accommodations
Ana M. Villamil - Program Manager, Centers for the Commercial 
  Development of Space

Office of Safety and Mission Quality
Col. Federick Gregory - Associate Administrator 
Dr. Charles Pellerin, Jr. - Deputy Associate Administrator 
Richard  Perry - Director, Programs Assurance 

KENNEDY SPACE CENTER, FLA.

Robert L. Crippen - Director
James A. "Gene" Thomas - Deputy Director
Jay F. Honeycutt - Director, Shuttle Management and 
Operations
Robert B. Sieck - Launch Director
Conrad G. Nagel - Atlantis Flow Director
J. Robert Lang - Director, Vehicle Engineering
Al J. Parrish - Director of Safety Reliability and
   Quality Assurance
John T. Conway - Director, Payload Management and Operations
P. Thomas Breakfield - Director, Shuttle Payload Operations
Joanne H. Morgan - Director, Payload Project Management
Robert W. Webster - STS-46 Payload Processing Manager

MARSHALL SPACE FLIGHT CENTER, HUNTSVILLE, ALA.

Thomas J. Lee - Director
Dr. J. Wayne Littles - Deputy Director
Harry G. Craft - Manager, Payload Projects Office
Billy Nunley - TSS-1 Mission Manager
Dr. Nobie Stone - TSS-1 Mission Scientist
Alexander A. McCool - Manager, Shuttle Projects Office
Dr. George McDonough - Director, Science and Engineering
James H. Ehl - Director, Safety and Mission Assurance
Otto Goetz - Manager, Space Shuttle Main Engine Project
Victor Keith Henson - Manager, Redesigned Solid
   Rocket Motor Project
Cary H. Rutland - Manager, Solid Rocket Booster Project
Gerald C. Ladner - Manager, External Tank Project

JOHNSON SPACE CENTER, HOUSTON, TEX.

Paul J. Weitz - Director (Acting)
Paul J. Weitz - Deputy Director
Daniel Germany - Manager, Orbiter and GFE Projects
Donald R. Puddy - Director, Flight Crew Operations
Eugene F. Krantz - Director, Mission Operations
Henry O. Pohl - Director, Engineering
Charles S. Harlan - Director, Safety, Reliability and Quality 
Assurance

STENNIS SPACE CENTER, BAY ST. LOUIS, MISS.

Roy S. Estess - Director
Gerald Smith - Deputy Director
J. Harry Guin - Director, Propulsion Test Operations

AMES-DRYDEN FLIGHT RESEARCH FACILITY, EDWARDS, CALIF.

Kenneth J. Szalai - Director
T. G. Ayers - Deputy Director
James R. Phelps - Chief, Space Support Office

AMES RESEARCH CENTER, MOUNTAIN VIEW, CALIF.

Dr. Dale L. Compton     Director
Victor L. Peterson      Deputy Director
Dr. Steven A. Hawley    Associate Director
Dr. Joseph C. Sharp     Director, Space Research

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