NASA
SPACE SHUTTLE MISSION STS-34
PRESS KIT

OCTOBER 1989

PUBLIC AFFAIRS CONTACTS

Sarah Keegan/Barbara Selby
Office of Space Flight
NASA Headquarters, Washington, D.C.

Charles Redmond/Paula Cleggett-Haleim
Office of Space Science and Applications
NASA Headquarters, Washington, D.C.

Jim Ball
Office of Commercial Programs
NASA Headquarters, Washington, D.C.

Lisa Malone
Kennedy Space Center, Fla.

Kyle Herring
Johnson Space Center, Houston, Texas

Jerry Berg
Marshall Space Flight Center, Huntsville, Ala.

Mack Herring
Stennis Space Center, Bay St. Louis, Miss.

Nancy Lovato
Ames-Dryden Flight Research Facility, Edwards, Calif.

Robert J. MacMillin
Jet Propulsion Laboratory, Pasadena, Calif.

Jim Elliott
Goddard Space Flight Center, Greenbelt, Md.

GENERAL RELEASE

RELEASE:  89-151

SHUTTLE ATLANTIS TO DEPLOY GALILEO PROBE TOWARD JUPITER

     Space Shuttle mission STS-34 will deploy the Galileo planetary
exploration spacecraft into low-Earth orbit starting Galileo on its journey
to explore Jupiter.  Galileo will be the second planetary probe deployed
from the Shuttle this year following Atlantis' successful launch of
Magellan toward Venus exploration in May.

     Following deployment about 6 hours after launch, Galileo will be
propelled on a trajectory, known as Venus-Earth-Earth Gravity Assist
(VEEGA) by an Air Force-developed, inertial upper stage (IUS).  Galileo's
trajectory will swing around Venus, the sun and Earth before Galileo
makes it's way toward Jupiter.

     Flying the VEEGA track, Galileo will arrive at Venus in February 1990. 
During the flyby, Galileo will make measurements to determine the
presence of lightning on Venus and take time-lapse photography of Venus'
cloud circulation patterns.  Accelerated by Venus' gravity, the spacecraft
will head back to Earth.

     Enroute, Galileo will activate onboard remote-sensing equipment to
gather near-infrared data on the composition and characteristics of the
far side of Earth's moon.  Galileo also will map the hydrogen distribution
of the Earth's atmosphere.

     Acquiring additional energy from the Earth's gravitational forces,
Galileo will travel on a 2-year journey around the sun spending 10 months
inside an asteroid belt.  On Oct. 29, 1991, Galileo wlll pass within 600
miles of the asteroid Gaspra.

     On the second Earth flyby in December 1992, Galileo will photograph
the north pole of the moon in an effort to determine if ice exists. 
Outbound, Galileo will activate the time-lapse photography system to
produce a "movie" of the moon orbiting Earth.

     Racing toward Jupiter, Galileo will make a second trek through the
asteroid belt passing within 600 miles of asteroid Ida on Aug. 29, 1993. 
Science data gathered from both asteroid encounters will focus on surface
geology and composition.

     Five months prior to the Dec. 7, 1995, arrival at Jupiter, Galileo's
atmospheric probe, encased in an oval heat shield, will spin away from the
orbiter at a rate of 5 revolutions per minute (rpm) and follow a ballistic
trajectory aimed at a spot 6 degrees north of Jupiter's equator.  The probe
will enter Jupiter's atmosphere at a shallow angle to avoid burning up like
a meteor or ricocheting off the atmosphere back into space.

     At approximately Mach 1 speed, the probe's pilot parachute will deploy,
removing the deceleration module aft cover.  Deployment of the main
parachute will follow, pulling the descent module out of the aeroshell to
expose the instrument-sensing elements.  During the 75-minute descent
into the Jovian atmosphere, the probe will use the orbiter to transmit
data back to Earth.  After 75 minutes, the probe will be crushed under the
heavy atmospheric pressure.

     The Galileo orbiter will continue its primary mission, orbiting around
Jupiter and four of its satellites, returning science data for the next 22
months.

     Galileo's scientific goals include the study of the chemical
composition, state and dynamics of the Jovian atmosphere and satellites,
and the investigation of the structure and physical dynamics of the
powerful Jovian magnetosphere.

     Overall responsibility for management of the project, including orbiter
development, resides at NASA's Jet Propulsion Laboratory, Pasadena,
Calif.  The NASA Ames Research Center, Mountain View, Calif., manages
the probe system.  JPL built the 2,500-lb. spacecraft and Hughes Aircraft
Co. built the 740-lb. probe.

     Modifications made to Galileo since flight postponement in 1986
include the addition of sunshields to the base and top of the antenna, new
thermal control surfaces, blankets and heaters.  Because of the extended
length of the mission, the electrical circuitry of the thermoelectric
generator has been revised to reduce power demand throughout the
mission to assure adequate power supply for mission completion.

     Joining Galileo in the payload bay of Atlantis will be the Shuttle Solar
Backscatter Ultraviolet (SSBUV) instrument.  The SSBUV is designed to
provide calibration of backscatter ultraviolet instruments currently being
flown on free-flying satellites.  SSBUV's primary objective is to check the
calibration of the ozone sounders on satellites to verify the accuracy of
the data set of atmospheric ozone and solar irradiance data.

     The SSBUV is contained in two Get Away Special canisters in the
payload bay and weighs about 1219 lbs .  One canister contains the SSBUV
spectrometer and five supporting optical sensors.  The second canister
houses data, command and power systems.  An interconnecting cable
provides the communication link between the two canisters.

     Atlantis also will carry several secondary payloads involving radiation
measurements, polymer morphology, lightning research, microgravity
effects on plants and a student experiment on ice crystal growth in space.

     Commander of the 31st Shuttle mission is Donald E. Williams, Captain,
USN.  Michael J. McCulley, Commander, USN, is Pilot.  Williams flew as
Pilot of mission STS 51-D in April 1985.  McCulley will be making his
first Shuttle flight.

     Mission Specialists are Shannon W. Lucid, Ph.D.; Franklin R. Chang-Diaz,
Ph.D.; and Ellen S. Baker, M.D.   Lucid previously flew as a Mission
Specialist on STS 51-G in June 1985.  Chang-Diaz flew as a Mission
Specialist on STS 61-C in January 1986.  Baker is making her first Shuttle
flight.

     Liftoff of the fifth flight of orbiter Atlantis is scheduled for 1:29 p.m.
EDT on Oct. 12 from Kennedy Space Center, Fla., launch pad 39-B, into a
160-nautical-mile, 34.3-degree orbit.  Nominal mission duration is 5
days, 2 hours, 45 minutes.  Deorbit is planned on orbit 81, with landing
scheduled for 4:14 p.m. EDT on Oct. 17 at Edwards Air Force Base, Calif.

     Liftoff on Oct. 12 could occur during a 10-minute period.  The launch
window grows each day reaching a maximum of 47 minutes on Nov. 2.  The
window then decreases each day through the remainder of the launch
opportunity which ends Nov. 21.  The window is dictated by the need for a
daylight landing opportunity at the trans-Atlantic landing abort sites and
the performance constraint of Galileo's inertial upper stage.

     After landing at Edwards AFB, Atlantis will be towed to the NASA
Ames-Dryden Flight Research Facility, hoisted atop the Shuttle Carrier
Aircraft and ferried back to the Kennedy Space Center to begin processing
for its next flight.

- end -

GENERAL INFORMATION

NASA Select Television Transmission

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

The schedule for tv transmissions from the orbiter and for the
change-of-shift briefings from Johnson Space Center, Houston, will be
available during the mission at Kennedy Space Center, Fla.; Marshall Space
Flight Center, Huntsville, Ala.; Johnson Space Center; and NASA
Headquarters, Washington, D.C.  The  schedule will be updated daily to
reflect changes dictated by mission operations.   

TV 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.  Voice updates of the TV schedule may be obtained by dialing
202/755-1788.  This service is updated daily at noon EDT. 

Special Note to Broadcasters

In the 5 workdays before launch, short sound bites of astronaut interviews
with the STS-34 crew will be available to broadcasters by calling
XXX/YYY-ZZZZ between 8 a.m. and noon EDT.

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

An STS-34 mission press briefing schedule will be issued prior to launch. 
During the mission, flight control personnel will be on 8-hour shifts. 
Change-of-shift briefings by the off-going flight director will occur at
approximately 8-hour intervals.

LAUNCH PREPARATIONS, COUNTDOWN AND LIFTOFF

     Processing activities began on Atlantis for the STS-34 mission on May
16 when Atlantis was towed to Orbiter Processing Facility (OPF) bay 2
after arrival from NASA's Ames-Dryden Flight Research Facility in
California.  STS-30 post-flight deconfiguration and inspections were
conducted in the processing hangar.

     As planned, the three main engines were removed the last week of May
and taken to the main engine shop in the Vehicle Assembly Building (VAB)
for the replacement of several components including the high pressure
oxidizer turbopumps. The engines were reinstalled  the first week of July,
while the ship was in the OPF.  Engine 2027 is installed in the number one
position, engine 2030 is in the number two position and engine 2029 is in
the number three position.

     The right hand Orbital Maneuvering System (OMS) pod was removed in
mid-June for repairs.  A propellant tank needed for Atlantis' pod was
scheduled for delivery too late to support integrated testing.  As a result,
Discovery's right pod was installed on Atlantis about 2 weeks later.  The
left OMS pod was removed July 9 and reinstalled 2 1/2 weeks later.  Both
pods had dynatubes and helium isolation valve repairs in the Hypergolic
Maintenance Facility.

     About 34 modifications have been implemented since the STS-30
mission.  One significant modification is a cooling system for the
radioisotope thermoelectric generators (RTG).  The RTG fuel is  plutonium
dioxide which generates heat as a result of its normal decay.  The heat is
converted to energy and used to provide electrical power for the Galileo
spacecraft.  A mixture of alcohol and water flows in the special cooling
system to lower the RTG case temperature and maintain a desired
temperature to the payload instrumentation in the vicinity of the RTGs. 
These cooling lines are mounted on the port side of the orbiter from the
aft compartment to a control panel in bay 4.

     Another modification, called "flutter buffet," features special
instrumentation on the vertical tail and right and left outboard elevons.
Ten accelerometers were added to the vertical tail and one on each of the
elevons.  These instruments are designed to measure in-flight loads on the
orbiter's structure.  Atlantis is the only vehicle that will be equipped with
this instrumentation.

     Improved controllers for the water spray boilers and auxiliary power
units were installed.  Other improvements were made to the orbiter's
structure and thermal protection system, mechanical systems, propulsion
system and avionics system.

     Stacking of solid rocket motor (SRM) segments for flight began with
the left aft booster on Mobile Launcher Platform 1 in the VAB on June 15. 
Booster stacking operations were completed by July 22 and the external
tank was mated to the two boosters on July 30.

     Flight crew members performed the Crew Equipment Interface Test on
July 29 to become familiar with Atlantis' crew compartment, vehicle
configuration and equipment associated with the mission.

     The Galileo probe arrived at the Spacecraft Assembly and
Encapsulation Facility (SAEF) 2 on April 17 and the spacecraft arrived on
May 16.  While at SAEF-2, the spacecraft and probe were joined and tested
together to verify critical connections.  Galileo was delivered to the
Vertical Processing Facility (VPF) on Aug. 1.  The Inertial Upper Stage
(IUS) was delivered to the VPF on July 30.  The Galileo/IUS were joined
together on Aug. 3 and all integrated testing was performed during the
second week of August.

     The Shuttle Solar Backscatter Ultraviolet (SSBUV) experiment,
contained in two Get Away Special (GAS) canisters, was mounted on a
special GAS beam in Atlantis' payload bay on July 24.  Interface
verification tests were performed the next day.

     Atlantis was transferred from the OPF to the VAB on Aug. 21, where it
was mated to the external tank and SRBs.  A Shuttle Interface Test was
conducted in the VAB to check the mechanical and electrical connections
between the various elements of the Shuttle vehicle and onboard flight
systems.

     The assembled Space Shuttle vehicle was rolled out of the VAB aboard
its mobile launcher platform for the 4.2 mile trip to Launch Pad 39-B on
Aug. 29.  Galileo and its IUS upper stage were transferred from the VPF to
Launch Pad 39-B on Aug. 25.  The payload was installed in Atlantis'
payload bay on Aug. 30.

     The payload interface verification test was planned for Sept. 7 to
verify connections between the Shuttle and the payload.  An end-to-end
test was planned for Sept. 8 to verify communications between the
spacecraft and ground controllers.  Testing of the IUS was planned about 2
weeks prior to launch in parallel with Shuttle launch preparations.

     A Countdown Demonstration Test, a dress rehearsal for the STS-34
flight crew and KSC launch team, is designed as a practice countdown for
the launch.  At press time, it was planned for Sept. 14 and 15.

     One of the unique STS-34 processing milestones planned was a
simulation exercise for the installation of the RTGs.  Simulated RTGs
were to be used in the 2-day event scheduled within the first week after
Atlantis arrives at the launch pad.  The test is designed to give workers
experience for the installation of the RTGs, a first in the Shuttle program.
In addition, access requirements will be identified and procedures will be
verified.

     Another test scheduled at the pad is installation of the flight RTGs and
an associated test and checkout of the RTG cooling system planned for the
third week of September.  This test will verify the total RTG cooling
system and connections.  The RTGs will be removed at the completion of
the 3-day cooling system test and returned to the RTG facility.  The two
flight RTGs will be reinstalled on the spacecraft 6 days before launch.

     Launch preparations scheduled the last 2 weeks prior to launch countdown
include final vehicle ordnance activities, such as power-on stray-voltage
checks and resistance checks of firing circuits; loading the fuel cell
storage tanks; pressurizing the hypergolic propellant tanks aboard the
vehicle; final payload closeouts; and a final functional check of the range
safety and SRB ignition, safe and arm devices.

     The launch countdown is scheduled to pick up at the T-minus 43-hour
mark, leading up to the STS-34 launch.  Atlantis' fifth launch will be
conducted by a joint NASA/industry team from Firing Room 1 in the Launch
Control Center.

MAJOR COUNTDOWN MILESTONES

Countdown	                 Event

T-43 Hours	Power up Space Shuttle vehicle.

T-34 Hours	Begin orbiter and ground support
		equipment closeouts for launch.

T-30 Hours	Activate orbiter's navigation aids.

T-27 Hours (holding)	Enter first built-in hold for 8 hours.

T-27 Hours (counting)	Begin preparations for loading fuel
		cell storage tanks with liquid oxygen
		and liquid hydrogen reactants.

T-25 Hours	Load orbiter's fuel cell tanks with
		liquid oxygen.

T-22 Hours, 30 minutes	Load orbiter's fuel cell tanks with
		liquid hydrogen.

T-22 Hours	Perform interface check between
		Houston Mission Control and Merritt
		Island  Launch Area (MILA) tracking
		station.

T-20 Hours	Activate and warm up inertial
		measurement units (IMU).

T-19 Hours (holding)	Enter 8-hour built-in hold. Activate
		orbiter communications system.

T-19 hours (counting)	Resume countdown.  Continue preparations to load
		external tank, orbiter closeouts and preparations
		to move the Rotating Service Structure (RSS). 

T-11 Hours (holding)	Start 14-hour, 40 minute built-in hold
		orbiter flight and middecks.

T-11 Hours (counting)	Retract RSS from vehicle to launch
		position.  

T-9 Hours	Activate orbiter's fuel cells.

T-8 Hours	Configure Mission Control communications
                for launch.  Start clearing
		blast danger area.

T-6 Hours, 30 minutes	Perform Eastern Test Range open
		loop command test.

T-6 Hours (holding)	Enter 1-hour built-in hold.  Receive
		management "go" for tanking.

T-6 Hours (counting)	Start external tank chilldown and
		propellant loading.

T-5 Hours	Start IMU pre-flight calibration.

T-4 Hours	Perform MILA antenna alignment.

T-3 Hours (holding)	2-hour built-in hold begins.  Loading
		of external tank is complete and in a
		stable replenish mode.  Ice team
		goes to pad for inspections.  Closeout
		crew goes to white room to begin
		preparing orbiter's cabin for flight
		crew's entry.  Wake flight crew
		(launch minus 4 hours, 55 minutes).

T-3 Hours (counting)	Resume countdown.

T-2 Hours, 55 minutes	Flight crew departs O&C Building for
		Launch Pad 39-B  (Launch minus 3
		hours,15 minutes).

T-2 Hours, 30 minutes	Crew enters orbiter vehicle  (Launch
		minus 2 Hours, 50 minutes).

T-60 minutes	Start pre-flight alignment of IMUs.

T-20 minutes (holding)	10-minute built-in hold begins.

T-20 minutes(counting)	Configure orbiter computers for
		launch.

T-10 minutes	White room closeout crew cleared
	        through launch danger are a
		roadblocks.

T-9 minutes (holding)	40-minute built-in hold begins.
		Perform status check and receive
		Launch Director and Mission
		Management Team "go."

T-9 minutes (counting)	Start ground launch sequencer.

T-7 minutes, 30 seconds	Retract orbiter access arm.

T-5 minutes	Pilot starts auxiliary power units. Arm
		range safety,  solid rocket booster
		(SRB) ignition systems.

T-3 minutes, 30 seconds	Orbiter goes on internal power.

T-2 minutes, 55 seconds	Pressurize liquid oxygen tank for
		flight and retract gaseous oxygen
		vent hood.

T-1 minute, 57 seconds	Pressurize liquid hydrogen tank.

T-31 seconds	"Go" from ground computer for
		orbiter computers to start the
		automatic launch sequence.

T-28 seconds	Start SRB hydraulic power units.

T-21 seconds	Start SRB gimbal profile test.

T-6.6 seconds	Main engine start.

T-3 seconds	Main engines at 90 percent thrust.

T-0	SRB ignition, holddown post release and liftoff.

T+7 seconds	Shuttle clears launch tower and
		control switches to JSC.

Note: This countdown timeline may be adjusted in real time as necessary.

TRAJECTORY SEQUENCE OF EVENTS
________________________________________________________________
                                       RELATIVE
EVENT                          MET     VELOCITY  MACH   ALTITUDE
                            (d:h:m:s)    (fps)            (ft.)
________________________________________________________________
Launch			   00/00:00:00
Begin Roll Maneuver 	   00/00:00:09     165     .15       627
End Roll Maneuver	   00/00:00:17     374     .33     2,898
SSME Throttle Down to 65%  00/00:00:34     833     .75    11,854
Max. Dyn. Pressure (Max Q) 00/00:00:52   1,260    1.2     28,037
SSME Throttle Up to 104%   00/00:01:01   1,499    1.49    38,681
SRB Staging		   00/00:02:04   4,316    3.91   153,873
Negative Return		   00/00:03:54   6,975    7.48   317,096
Main Engine Cutoff (MECO)  00/00:08:27  24,580   22.41   366,474
Zero Thrust		   00/00:08:33  24,596   22.17   368,460
ET Separation		   00/00:08:45
OMS 2 Burn		   00/00:39:48
Galileo/IUS Deploy (orb 5) 00/06:21:36
Deorbit Burn (orbit 81)	   05/01:45:00
Landing (orbit 82)	   05/02:45:00

Apogee, Perigee at MECO:	157 x  39 nm
Apogee, Perigee post-OMS 2:	161 x 161 nm
Apogee, Perigee post deploy:	177 x 161 nm

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 Edwards Air Force
Base, Calif.; White Sands Space Harbor (Northrup Strip), N.M.; or the Shuttle
Landing Facility (SLF) at Kennedy Space Center (KSC), Fla.

* Trans-Atlantic Abort Landing (TAL) -- Loss of two main engines midway
through powered flight would force a landing at Ben Guerir, Morocco; Moron,
Spain; or Banjul, The Gambia.

* Return-To-Launch-Site (RTLS) -- Early shutdown of one or more engines
and 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-34 contingency landing sites are Edwards AFB, White Sands, KSC, Ben
Guerir, Moron and Banjul.

SUMMARY OF MAJOR ACTIVITIES

Day One

Ascent
Post-insertion checkout
Pre-deploy checkout
Galileo/Inertial Upper Stage (IUS) deploy
Detailed Secondary Objective (DSO)
Polymer Morphology (PM)
Sensor Technology Experiment (STEX) activation

Day Two

Galileo/IUS backup deploy opportunity
DSO
IMAX
PM
Shuttle Solar Backscatter Ultraviolet (SSBUV) activation
Shuttle Student Involvement Program (SSIP)

Day Three

DSO
IMAX
Mesoscale Lightning Experiment (MLE)
PM

Day Four

DSO
IMAX
MLE
PM
SSBUV deactivation

Day Five

DTO/DSO
GHCD operations
PM
STEX deactivation
Flight control systems (FCS) checkout
Cabin stow
Landing preparations

Day Six

PM stow
Deorbit preparation
Deorbit burn
Landing at Edwards AFB

LANDING AND POST LANDING OPERATIONS

     Kennedy Space Center, Fla., is responsible for ground  operations of the
orbiter once it has rolled to a stop on the runway at Edwards Air Force
Base, Calif.  Those operations include preparing the Shuttle for the return
trip to Kennedy.

     After landing, the flight crew aboard Atlantis begins "safing" vehicle
systems.  Immediately after wheel stop, specially garbed technicians will
first determine that any residual hazardous vapors are below significant
levels for other safing operations to proceed.

     A mobile white room is moved into place around the crew hatch once it
is verified that there are no concentrations of toxic gases around the
forward part of the vehicle.  The flight crew is expected to leave Atlantis
about 45 to 50 minutes after landing.  As the crew exits, technicians enter
the orbiter to complete the vehicle safing activity.

     Once the initial aft safety assessment is made, access vehicles  are 
positioned  around the rear of the orbiter so that lines from the ground
purge and cooling vehicles can be connected to the umbilical panels on the
aft end of Atlantis.

     Freon line connections are completed and coolant begins circulating
through the umbilicials to aid in heat rejection and protect the orbiter's
electronic equipment.  Other lines provide cooled, humidified air to the
payload bay and other cavities to remove any residual fumes and provide a
safe environment inside Atlantis.

     A tow tractor will be connected to Atlantis and the vehicle will be 
pulled off the runway at Edwards and positioned inside the Mate/Demate
Device (MDD) at nearby Ames-Dryden Flight Research Facility.  After the
Shuttle has been jacked and leveled, residual fuel cell cryogenics are
drained and unused pyrotechnic devices are disconnected prior to returning
the orbiter to Kennedy.

     The aerodynamic tail cone is installed over the three main engines,
and the orbiter is bolted on top of the 747 Shuttle Carrier Aircraft for the 
ferry flight back to Florida.  Pending completion of planned work and
favorable weather conditions, the 747 would depart California about 6 days
after landing for the cross-country ferry flight back to Florida.  A refueling
stop is necessary to complete the journey.

     Once back at Kennedy, Atlantis will be pulled inside the hangar-like
facility for post-flight inspections and in-flight anomaly troubleshooting. 
These operations are conducted in parallel with the start of routine
systems reverification to prepare Atlantis for its next mission. 

GALILEO

     Galileo is a NASA spacecraft mission to Jupiter to study the planet's
atmosphere, satellites and surrounding magnetosphere.  It was named for
the Italian renaissance scientist who discovered Jupiter's major moons by
using the first astronomical telescope.

     This mission will be the first to make direct measurements from an
instrumented probe within Jupiter's atmosphere and the first to conduct
long-term observations of the planet and its magnetosphere and satellites
from orbit around Jupiter.  It will be the first orbiter and atmospheric
probe for any of the outer planets.  On the way to Jupiter, Galileo also will
observe Venus, the Earth-moon system, one or two asteroids and various
phenomena in interplanetary space.

     Galileo will be boosted into low-Earth orbit by the Shuttle Atlantis and
then boosted out of Earth orbit by a solid rocket Inertial Upper Stage.  The
spacecraft will fly past Venus and twice by the Earth, using gravity assists
from the planets to pick up enough speed to reach Jupiter.  Travel time from
launch to Jupiter is a little more than 6 years.

     In December 1995, the Galileo atmospheric probe will conduct a brief,
direct examination of Jupiter's atmosphere, while the larger part of the
craft, the orbiter, begins a 22-month, 10-orbit tour of major satellites and
the magnetosphere, including long-term observations of Jupiter throughout
this phase.

     The 2-ton Galileo orbiter spacecraft carries 9 scientific instruments. 
There are another six experiments on the 750-pound probe.  The spacecraft
radio link to Earth serves as an additional instrument for  scientific
measurements.  The probe's scientific data will be relayed to Earth by the
orbiter during the 75-minute period while the probe is descending into
Jupiter's atmosphere.  Galileo will communicate with its controllers and
scientists through NASA's Deep Space Network, using tracking stations in
California, Spain and Australia.

GALILEO MISSION EVENTS

Launch Window (Atlantis and IUS)       Oct. 12 to Nov. 21, 1989
(Note:  for both asteroids, closes in mid-October)
Venus flyby ( 9,300 mi)               *Feb. 9, 1990
Venus data playback                    Oct. 1990
Earth 1 flyby ( about 600 mi)         *Dec. 8, 1990
Asteroid Gaspra flyby (600 mi)        *Oct. 29, 1991
Earth 2 flyby (200 mi)                *Dec. 8, 1992
Asteroid Ida flyby (600 mi)           *Aug. 28, 1993
Probe release                          July 1995
Jupiter arrival                        Dec. 7, 1995
(includes Io flyby, probe entry and relay, Jupiter orbit insertion)
Orbital tour of Galilean satellites    Dec '95-Oct '97

*Exact dates may vary according to actual launch date

EARTH TO JUPITER

     Galileo will make three planetary encounters in the course of its
gravity-assisted flight to Jupiter.  These provide opportunities for
scientific observation and measurement of Venus and the Earth-moon
system.  The mission also has a chance to fly close to one or two asteroids,
bodies which have never been observed close up, and obtain data on other
phenomena of interplanetary space.

     Scientists are currently studying how to use the Galileo scientific
instruments and the limited ability to collect, store and transmit data
during the early phase of flight to make the best use of these opportunities. 
Instruments designed to observe Jupiter's atmosphere from afar can
improve our knowledge of the atmosphere of Venus and sensors designed for
the study of Jupiter's moons can add to our information about our own moon.

VENUS

     The Galileo spacecraft will approach Venus early in 1990 from the night
side and pass across the sunlit hemisphere, allowing observation of the
clouds and atmosphere.  Both infrared and ultraviolet spectral observations
are planned, as well as several camera images and other remote
measurements.  The search for deep cloud patterns and for lightning storms
will be limited by the fact that all the Venus data must be tape-recorded on
the spacecraft for playback 8 months later.

     The spacecraft was originally designed to operate between Earth and
Jupiter, where sunlight is 25 times weaker than at Earth and temperatures
are much lower.  The VEEGA mission will expose the spacecraft to a hotter
environment from Earth to Venus and back.  Spacecraft engineers devised a
set of sunshades to protect the craft.  For this system to work, the front
end of the spacecraft must be aimed precisely at the Sun, with the main
antenna furled for protection from the Sun's rays until after the first Earth
flyby in December 1990.  This precludes the use of the Galileo high-gain
antenna and therefore, scientists must wait until the spacecraft is close to
Earth to receive the recorded Venus data, transmitted through a low-gain
antenna.

FIRST EARTH PASS

     Approaching Earth for the first time about 14 months after launch, the
Galileo spacecraft will observe, from a distance, the nightside of Earth and
parts of both the sunlit and unlit sides of the moon.  After passing Earth,
Galileo will observe Earth's sunlit side.  At this short range, scientific data
are transmitted at the high rate using only the spacecraft's low-gain
antennas.  The high-gain antenna is to be unfurled like an umbrella, and its
high-power transmitter turned on and checked out, about 5 months after the
first Earth encounter.

FIRST ASTEROID

     Nine months after the Earth passage and still in an elliptical solar orbit,
Galileo will enter the asteroid belt, and two months later, will have its
first asteroid encounter.  Gaspra is believed to be a fairly representative
main-belt asteroid, about 10 miles across and probably similar in
composition to stony meteorites.

     The spacecraft will pass within about 600 miles at a relative speed of
about 18,000 miles per hour.  It will collect several pictures of Gaspra and
make spectral measurements to indicate its composition and physical
properties.

SECOND EARTH PASS

     Thirteen months after the Gaspra encounter, the spacecraft will have
completed its 2-year elliptical orbit around the Sun and will arrive back at
Earth.  It will need a much larger ellipse (with a 6-year period) to reach as
far as Jupiter.  The second flyby of Earth will pump the orbit up to that
size, acting as a natural apogee kick motor for the Galileo spacecraft.

     Passing about 185 miles above the surface, near the altitude at which it
had been deployed from the Space Shuttle almost three years earlier,
Galileo will use Earth's gravitation to change the spacecraft's flight
direction and pick up about 8,000 miles per hour in speed.

     Each gravity-assist flyby requires about three rocket-thrusting
sessions, using Galileo's onboard retropropulsion module, to fine-tune the
flight path.  The asteroid encounters require similar maneuvers to obtain
the best observing conditions.

     Passing the Earth for the last time, the spacecraft's scientific
equipment will make thorough observations of the planet, both for
comparison with Venus and Jupiter and to aid in Earth studies.  If all goes
well, there is a good chance that Galileo will enable scientists to record
the motion of the moon about the Earth while the Earth itself rotates.

SECOND ASTEROID

     Nine months after the final Earth flyby, Galileo may have a second
asteroid-observing opportunity.  Ida is about 20 miles across.  Like Gaspra,
Ida is believed to represent the majority of main-belt asteroids in
composition, though there are believed to be differences between the two. 
Relative velocity for this flyby will be nearly 28,000 miles per hour, with a
planned closest approach of about 600 miles.

APPROACHING JUPITER

     Some 2 years after leaving Earth for the third time and 5 months before
reaching Jupiter, Galileo's probe must separate from the orbiter.  The
spacecraft turns to aim the probe precisely for its entry point in the
Jupiter atmosphere, spins up to 10 revolutions per minute and releases the
spin-stabilized probe.  Then the Galileo orbiter maneuvers again to aim for
its own Jupiter encounter and resumes its scientific measurements of the
interplanetary environment underway since the launch more than 5 years
before.

     While the probe is still approaching Jupiter, the orbiter will have its
first two satellite encounters.  After passing within 20,000 miles of
Europa, it will fly about 600 miles above Io's volcano-torn surface, twenty
times closer than the closest flyby altitude of Voyager in 1979.

AT JUPITER

The Probe at Jupiter

     The probe mission has four phases:  launch, cruise, coast and
entry-descent.  During launch and cruise, the probe will be carried by the
orbiter and serviced by a common umbilical.  The probe will be dormant
during cruise except for annual checkouts of spacecraft systems and
instruments.  During this period, the orbiter will provide the probe with
electric power, commands, data transmission and some thermal control.

     Six hours before entering the atmosphere, the probe will be shooting
through space at about 40,000 mph.  At this time, its command unit signals
"wake up" and instruments begin collecting data on lightning, radio
emissions and energetic particles.

     A few hours later, the probe will slam into Jupiter's atmosphere at
115,000 mph, fast enough to jet from Los Angeles to New York in 90
seconds.  Deceleration to about Mach 1 -- the speed of sound -- should take
just a few minutes.  At maximum deceleration as the craft slows from
115,000 mph to 100 mph, it will be hurtling against a force 350 times
Earth's gravity.  The incandescent shock wave ahead of the probe will be as
bright as the sun and reach searing temperatures of up to 28,000 degrees
Fahrenheit.  After the aerodynamic braking has slowed the probe, it will
drop its heat shields and deploy its parachute.  This will allow the probe to
float down about 125 miles through the clouds, passing from a pressure of
1/10th that on Earth's surface to about 25 Earth atmospheres.

     About 4 minutes after probe entry into Jupiter's atmosphere, a pilot
chute deploys and explosive nuts shoot off the top section of the probe's
protective shell.  As the cover whips away, it pulls out and opens the main
parachute attached to the inner capsule.  What remains of the probe's outer
shell, with its massive heat shield, falls away as the parachute slows the
instrument module.

     From there on, suspended from the main parachute, the probe's capsule
with its activated instruments floats downward toward the bright clouds
below.

     The probe will pass through the white cirrus clouds of ammonia crystals
- the highest cloud deck.  Beneath this ammonia layer probably lie
reddish-brown clouds of ammonium hydrosulfides.  Once past this layer, the
probe is expected to reach thick water clouds.  This lowest cloud layer may
act as a buffer between the uniformly mixed regions below and the
turbulent swirl of gases above.

     Jupiter's atmosphere is primarily hydrogen and helium.  For most of its
descent through Jupiter's three main cloud layers, the probe will be
immersed in gases at or below room temperature.  However, it may
encounter hurricane winds up to 200 mph and lightning and heavy rain at the
base of the water clouds believed to exist on the planet.  Eventually, the
probe will sink below these clouds, where rising pressure and temperature
will destroy it.  The probe's active life in Jupiter's atmosphere is expected
to be about 75 minutes in length.  The probe batteries are not expected to
last beyond this point, and the relaying orbiter will move out of reach.

     To understand this huge gas planet, scientists must find out about its
chemical components and the dynamics of its atmosphere.  So far,
scientific data are limited to a two-dimensional view (pictures of the
planet's cloud tops) of a three-dimensional process (Jupiter's weather).  But
to explore such phenomena as the planet's incredible coloring, the Great Red
Spot and the swirling shapes and high-speed motion of its topmost clouds,
scientists must penetrate Jupiter's visible surface and investigate the
atmosphere concealed in the deep-lying layers below.

     A set of six scientific instruments on the probe will measure, among
other things, the radiation field near Jupiter, the temperature, pressure,
density and composition of the planet's atmosphere from its first faint
outer traces to the hot, murky hydrogen atmosphere 100 miles below the
cloud tops.  All of the information will be gathered during the probe's
descent on an 8-foot parachute.  Probe data will be sent to the Galileo
Orbiter 133,000 miles overhead then relayed across the half billion miles
to Deep Space Network stations on Earth.

     To return its science, the probe relay radio aboard the orbiter must
automatically acquire the probe signal below within 50 seconds, with a
success probability of 99.5 percent.  It must reacquire the signal
immediately should it become lost.

     To survive the heat and pressure of entry, the probe spacecraft is
composed of two separate units:  an inner capsule containing the scientific
instruments, encased in a virtually impenetrable outer shell.  The probe
weighs 750 pounds.  The outer shell is almost all heat shield material.

The Orbiter at Jupiter

     After releasing the probe, the orbiter will use its main engine to go into
orbit around Jupiter.  This orbit, the first of 10 planned, will have a period
of about 8 months.  A close flyby of Ganymede in July 1996 will shorten the
orbit, and each time the Galileo orbiter returns to the inner zone of
satellites, it will make a gravity-assist close pass over one or another of
the satellites, changing Galileo's orbit while making close observations. 
These satellite encounters will be at altitudes as close as 125 miles above
their surfaces.  Throughout the 22-month orbital phase, Galileo will
continue observing the planet and the satellites and continue gathering data
on the magnetospheric environment. 

SCIENTIFIC ACTIVITIES

     Galileo's scientific experiments will be carried out by more than 100
scientists from six nations.  Except for the radio science investigation,
these are supported by dedicated instruments on the Galileo orbiter and
probe.  NASA has appointed 15 interdisciplinary scientists whose studies
include data from more than one Galileo instrument.

      The instruments aboard the probe will measure the temperatures and
pressure of Jupiter's atmosphere at varying altitudes and determine its
chemical composition including major and minor constituents (such as
hydrogen, helium, ammonia, methane, and water) and the ratio of hydrogen
to helium.  Jupiter is thought to have a bulk composition similar to that of
the primitive solar nebula from which it was formed.  Precise
determination of the ratio of hydrogen to helium would provide an
important factual check of the Big Bang theory of the genesis of the
universe.

     Other probe experiments will determine the location and structure of
Jupiter's clouds, the existence and nature of its lightning, and the amount
of heat radiating from the planet compared to the heat absorbed from
sunlight.

     In addition, measurements will be made of Jupiter's numerous radio
emissions and of the high-energy particles trapped in the planet's
innermost magnetic field.  These measurements for Galileo will be made
within a distance of 26,000 miles from Jupiter's cloud tops, far closer than
the previous closest approach to Jupiter by Pioneer 11.  The probe also will
determine vertical wind shears using Doppler radio measurements made of
probe motions from the radio receiver aboard the orbiter.

     Jupiter appears to radiate about twice as much energy as it receives
from the sun and the resulting convection currents from Jupiter's internal
heat source towards its cooler polar regions could explain some of the
planet's unusual weather patterns.

     Jupiter is over 11 times the diameter of Earth and spins about two and
one-half times faster -- a jovian day is only 10 hours long.  A point on the
equator of Jupiter's visible surface races along at 28,000 mph.  This rapid
spin may account for many of the bizarre circulation patterns observed on
the planet.

Spacecraft Scientific Activities

     The Galileo mission and systems were designed to investigate three
broad aspects of the Jupiter system: the planet's atmosphere, the satellites
and the magnetosphere.  The spacecraft is in three segments to focus on
these areas: the atmospheric probe; a non-spinning section of the orbiter
carrying cameras and other remote sensors; and the spinning main section
of the orbiter spacecraft which includes the propulsion module, the
communications antennas, main computers and most support systems as
well as the fields and particles instruments, which sense and measure the
environment directly as the spacecraft flies through it.

Probe Scientific Activities

     The probe will enter the atmosphere about 6 degrees north of the
equator.  The probe weighs just under 750 pounds and includes a
deceleration module to slow and protect the descent module, which carries
out the scientific mission.

     The deceleration module consists of an aeroshell and an aft cover
designed to block the heat generated by slowing from the probe's arrival
speed of about 115,000 miles per hour to subsonic speed in less than 2
minutes.  After the covers are released, the descent module deploys its
8-foot  parachute and its instruments, the control and data system, and the
radio-relay transmitter go to work.

     Operating at 128 bits per second, the dual L-band transmitters send
nearly identical streams of scientific data to the orbiter.  The probe's relay
radio aboard the orbiter will have two redundant receivers that process
probe science data, plus radio science and engineering data for
transmission to the orbiter communications system.  Minimum received
signal strength is 31 dBm.  The receivers also measure signal strength and
Doppler shift as part of the experiments for measuring wind speeds and
atmospheric absorption of radio signals.

     Probe electronics are powered by long-life, high-discharge-rate 34-volt
lithium batteries, which remain dormant for more than 5 years during the
journey to Jupiter.  The batteries have an estimated capacity of about 18
amp-hours on arrival at Jupiter.

Orbiter Scientific Activities

     The orbiter, in addition to delivering the probe to Jupiter and relaying
probe data to Earth, will support all the scientific investigations of Venus,
the Earth and moon, asteroids and the interplanetary medium, Jupiter's
satellites and magnetosphere, and observation of the giant planet itself.

     The orbiter weighs about 5,200 pounds including about 2,400 pounds of
rocket propellant to be expended in some 30 relatively small maneuvers
during the long gravity-assisted flight to Jupiter, the large thrust
maneuver which puts the craft into its Jupiter orbit, and the 30 or so trim
maneuvers planned for the satellite tour phase.

     The retropropulsion module consists of 12 10-newton thrusters, a single
400-newton engine, and the fuel, oxidizer, and pressurizing-gas tanks,
tubing, valves and control equipment.  (A thrust of 10 newtons would
support a weight of about 2.2 pounds at Earth's surface).  The propulsion
system was developed and built by Messerschmitt-Bolkow-Blohm and
provided by the Federal Republic of Germany.

     The orbiter's maximum communications rate is 134 kilobits per second
(the equivalent of about one black-and-white image per minute); there are
other data rates, down to 10 bits per second, for transmitting engineering
data under poor conditions.  The spacecraft transmitters operate at S-band
and X-band (2295 and 8415 megahertz) frequencies between Earth and on
L-band between the probe.

     The high-gain antenna is a 16-foot umbrella-like reflector unfurled
after the first Earth flyby.  Two low-gain antennas (one pointed forward
and one aft, both mounted on the spinning section) are provided to support
communications during the Earth-Venus-Earth leg of the flight and
whenever the main antenna is not deployed and pointed at Earth.  The despun
section of the orbiter carries a radio relay antenna for receiving the probe's
data transmissions.

     Electrical power is provided to Galileo's equipment by two radioisotope
thermoelectric generators.  Heat produced by natural radioactive decay of
plutonium 238 dioxide is converted to approximately 500 watts of
electricity (570 watts at launch, 480 at the end of the mission) to operate
the orbiter equipment for its 8-year active period.  This is the same type of
power source used by the Voyager and Pioneer Jupiter spacecraft in their
long outer-planet missions, by the Viking lander spacecraft on Mars and the
lunar scientific packages left on the Moon.

     Most spacecraft are stabilized in flight either by spinning around a
major axis or by maintaining a fixed orientation in space, referenced to the
sun and another star.  Galileo represents a hybrid of these techniques, with
a spinning section rotating ordinarily at 3 rpm and a "despun" section which
is counter-rotated to provide a fixed orientation for cameras and other
remote sensors.

     Instruments that measure fields and particles, together with the main
antenna, the power supply, the propulsion module, most of the computers
and control electronics, are mounted on the spinning section.  The
instruments include magnetometer sensors mounted on a 36-foot boom to
escape interference from the spacecraft; a plasma instrument detecting
low-energy charged particles and a plasma-wave detector to study waves
generated in planetary magnetospheres and by lightning discharges; a
high-energy particle detector; and a detector of cosmic and Jovian dust.

     The despun section carries instruments and other equipment whose
operation depends on a fixed orientation in space.  The instruments include
the camera system; the near-infrared mapping spectrometer to make
multispectral images for atmosphere and surface chemical analysis; the
ultraviolet spectrometer to study gases and ionized gases; and the
photopolarimeter radiometer to measure radiant and reflected energy.  The
camera system is expected to obtain images of Jupiter's satellites at
resolutions from 20 to 1,000 times better than Voyager's best.

     This section also carries a dish antenna to track the probe in Jupiter's
atmosphere and pick up its signals for relay to Earth.  The probe is carried
on the despun section, and before it is released, the whole spacecraft is
spun up briefly to 10 rpm in order to spin-stabilize the probe.

     The Galileo spacecraft will carry out its complex operations, including
maneuvers, scientific observations and communications, in response to
stored sequences which are interpreted and executed by various on-board
computers.  These sequences are sent up to the orbiter periodically through
the Deep Space Network in the form of command loads. 

GROUND SYSTEMS

     Galileo communicates with Earth via NASA's Deep Space Network (DSN),
which has a complex of large antennas with receivers and transmitters
located in the California desert, another in Australia and a third in Spain,
linked to a network control center at NASA's Jet Propulsion Laboratory in
Pasadena, Calif.  The spacecraft receives commands, sends science and
engineering data, and is tracked by Doppler and ranging measurements
through this network.

 At JPL, about 275 scientists, engineers and technicians, will be supporting
the mission at launch, increasing to nearly 400 for Jupiter operations
including support from the German retropropulsion team at their control
center in the FGR.  Their responsibilities include spacecraft command,
interpreting engineering and scientific data from Galileo to understand its
performance, and analyzing navigation data from the DSN.  The controllers
use a set of complex computer programs to help them control the
spacecraft and interpret the data.

     Because the time delay in radio signals from Earth to Jupiter and back is
more than an hour, the Galileo spacecraft was designed to operate from
programs sent to it in advance and stored in spacecraft memory.  A single
master sequence program can cover 4 weeks of quiet operations between
planetary and satellite encounters.  During busy Jupiter operations, one
program covers only a few days.  Actual spacecraft tasks are carried out by
several subsystems and scientific instruments, many of which work from
their own computers controlled by the main sequence.

     Designing these sequences is a complex process balancing the desire to
make certain scientific observations with the need to safeguard the
spacecraft and mission.  The sequence design process itself is supported by
software programs, for example, which display to the scientist maps of the
instrument coverage on the surface of an approaching satellite for a given
spacecraft orientation and trajectory.  Notwithstanding these aids, a
typical 3-day satellite encounter may take efforts spread over many
months to design, check and recheck.  The controllers also use software
designed to check the command sequence further against flight rules and
constraints.

     The spacecraft regularly reports its status and health through an
extensive set of engineering measurements.  Interpreting these data into
trends and averting or working around equipment failures is a major task
for the mission operations team.  Conclusions from this activity become an
important input, along with scientific plans, to the sequence design
process.  This too is supported by computer programs written and used in
the mission support area.

Navigation is the process of estimating, from radio range and Doppler
measurements, the position and velocity of the spacecraft to predict its
flight path and design course-correcting maneuvers.  These calculations
must be done with computer support.  The Galileo mission, with its complex
gravity-assist flight to Jupiter and 10 gravity-assist satellite encounters
in the Jovian system, is extremely dependent on consistently accurate
navigation.

     In addition to the programs that directly operate the spacecraft and are
periodically transmitted to it, the mission operations team uses software
amounting to 650,000 lines of programming code in the sequence design
process; 1,615,000 lines in the telemetry interpretation; and 550,000 lines
of code in navigation.  These must all be written, checked, tested, used in
mission simulations and, in many cases, revised before the mission can
begin.

     Science investigators are located at JPL or other university laboratories
and linked by computers.  From any of these locations, the scientists can be
involved in developing the sequences affecting their experiments and, in
some cases, in helping to change preplanned sequences to follow up on
unexpected discoveries with second looks and confirming observations.

JUPITER'S SYSTEM

     Jupiter is the largest and fastest-spinning planet in the solar system. 
Its radius is more than 11 times Earth's, and its mass is 318 times that of
our planet.  Named for the chief of the Roman gods, Jupiter contains more
mass than all the other planets combined.  It is made mostly of light
elements, principally hydrogen and helium.  Its atmosphere and clouds are
deep and dense, and a significant amount of energy is emitted from its
interior.

     The earliest Earth-based telescopic observations showed bands and
spots in Jupiter's atmosphere.  One storm system, the Red Spot, has been
seen to persist over three centuries.

     Atmospheric forms and dynamics were observed in increasing detail
with the Pioneer and Voyager flyby spacecraft, and Earth-based infrared
astronomers have recently studied the nature and vertical dynamics of
deeper clouds.

     Sixteen satellites are known.  The four largest, discovered by the Italian
scientist Galileo Galilei in 1610, are the size of small planets.  The
innermost of these, Io, has active sulfurous volcanoes, discovered by
Voyager 1 and further observed by Voyager 2 and Earth-based infrared
astronomy.  Io and Europa are about the size and density of Earth's moon (3
to 4 times the density of water) and probably rocky inside.  Ganymede and
Callisto, further out from Jupiter, are the size of Mercury but less than
twice as dense as water.  Their cratered surfaces look icy in Voyager
images, and they may be composed partly of ice or water.

     Of the other satellites, eight (probably captured asteroids) orbit
irregularly far from the planet, and four (three discovered by the Voyager
mission in 1979) are close to the planet.  Voyager also discovered a thin
ring system at Jupiter in 1979.

     Jupiter has the strongest planetary magnetic field known.  The resulting
magnetosphere is a huge teardrop-shaped, plasma-filled cavity in the solar
wind pointing away from the sun.  Jupiter's magnetosphere is the largest
single entity in our solar system, measuring more than 14 times the
diameter of the sun.  The inner part of the magnetic field is doughnut-
shaped, but farther out it flattens into a disk.  The magnetic poles are
offset and tilted relative to Jupiter's axis of rotation, so the field appears
to wobble with Jupiter's rotation (just under 10 hours), sweeping up and
down across the inner satellites and making waves throughout the
magnetosphere. 

WHY JUPITER INVESTIGATIONS ARE IMPORTANT

     With a thin skin of turbulent winds and brilliant, swift-moving clouds,
the huge sphere of Jupiter is a vast sea of liquid hydrogen and helium. 
Jupiter's composition (about 88 percent hydrogen and 11 percent helium
with small amounts of methane, ammonia and water) is thought to resemble
the makeup of the solar nebula, the cloud of gas and dust from which the
sun and planets formed.  Scientists believe Jupiter holds important clues to
conditions in the early solar system and the process of planet formation.

     Jupiter may also provide insights into the formation of the universe
itself.  Since it resembles the interstellar gas and dust  that are thought to
have been created in the "Big Bang," studies of Jupiter may help scientists
calibrate models of the beginning of the universe.

     Though starlike in composition, Jupiter is too small to generate
temperatures high enough to ignite nuclear fusion, the process that powers
the stars.  Some scientists believe that the sun and Jupiter began as
unequal partners in a binary star system.  (If a double star system had
developed, it is unlikely life could have arisen in the solar system.)  While
in a sense a "failed star," Jupiter is almost as large as a planet can be.  If
it contained more mass, it would not have grown larger, but would have shrunk
from compression by its own gravity.  If it were 100 times more massive,
thermonuclear reactions would ignite, and Jupiter would be a star.

     For a brief period after its formation, Jupiter was much hotter, more
luminous, and about 10 times larger than it is now, scientists believe.  Soon
after accretion (the condensation of a gas and dust cloud into a planet), its
brightness dropped from about one percent of the Sun's to about one
billionth -- a decline of ten million times.

     In its present state Jupiter emits about twice as much heat as it
receives from the Sun.  The loss of this heat -- residual energy left over
from the compressive heat of accretion -- means that Jupiter is cooling and
losing energy at a tremendously rapid rate.  Temperatures in Jupiter's core,
which were about 90,000 degrees Fahrenheit in the planet's hot, early
phase, are now about 54,000 degrees Fahrenheit, 100 times hotter than any
terrestrial surface, but 500 times cooler than the temperature at the
center of the sun.  Temperatures on Jupiter now range from 54,000 degrees
Fahrenheit at the core to minus 248 degrees Fahrenheit at the top of the
cloud banks.

     Mainly uniform in composition, Jupiter's structure is determined by
gradations in temperature and pressure.  Deep in Jupiter's interior there is
thought to be a small rocky core, comprising about four percent of the
planet's mass.  This "small" core (about the size of 10 Earths) is surrounded
by a 25,000-mile-thick layer of liquid metallic hydrogen.  (Metallic
hydrogen is liquid, but sufficiently compressed to behave as metal.) 
Motions of this liquid "metal" are the source of the planet's enormous
magnetic field.  This field is created by the same dynamo effect found in
the metallic cores of Earth and other planets.

     At the outer limit of the metallic hydrogen layer, pressures equal three
million times that of Earth's atmosphere and the temperature has cooled to
19,000 degrees Fahrenheit.

     Surrounding the central metallic hydrogen region is an outer shell of
"liquid" molecular hydrogen.  Huge pressures compress Jupiter's gaseous
hydrogen until, at this level, it behaves like a liquid.  The liquid hydrogen
layer extends upward for about 15,000 miles.  Then it gradually becomes
gaseous.  This transition region between liquid and gas marks, in a sense,
where the solid and liquid planet ends and its atmosphere begins.

     From here, Jupiter's atmosphere extends up for 600 more miles, but only
in the top 50 miles are found the brilliant bands of clouds for which Jupiter
is known.  The tops of these bands are colored bright yellow, red and orange
from traces of phosphorous and sulfur.  Five or six of these bands,
counterflowing east and west, encircle the planet in each hemisphere.  At
one point near Jupiter's equator, east winds of 220 mph blow right next to
west winds of 110 mph.  At boundaries of these bands, rapid changes in
wind speed and direction create large areas of turbulence and shear.  These
are the same forces that create tornados here on Earth.  On Jupiter, these
"baroclinic instabilities" are major phenomena, creating chaotic, swirling
winds and spiral features such as White Ovals.

     The brightest cloud banks, known as zones, are believed to be higher,
cooler areas where gases are ascending.  The darker bands, called belts, are
thought to be warmer, cloudier regions of descent.

     The top cloud layer consists of white cirrus clouds of ammonia crystals,
at a pressure six-tenths that of Earth's atmosphere at sea level (.6 bar). 
Beneath this layer, at a pressure of about two Earth atmospheres (2 bars)
and a temperature of near minus 160 degrees Fahrenheit, a reddish-brown
cloud of ammonium hydrosulfide is predicted.

     At a pressure of about 6 bars, there are believed to be clouds of water
and ice.  However, recent Earth-based spectroscopic studies suggest that
there may be less water on Jupiter than expected.  While scientists
previously believed Jupiter and the sun would have similar proportions of
water, recent work indicates there may be 100 times less water on Jupiter
than if it had a solar mixture of elements.  If this is the case, there may be
only a thin layer of water-ice at the 6 bar level.

     However, Jupiter's cloud structure, except for the highest layer of
ammonia crystals, remains uncertain.  The height of the lower clouds is
still theoretical -- clouds are predicted to lie at the temperature levels
where their assumed constituents are expected to condense.  The Galileo
probe will make the first direct observations of Jupiter's lower atmosphere
and clouds, providing crucial information.

     The forces driving Jupiter's fast-moving winds are not well understood
yet.  The classical explanation holds that strong currents are created by
convection of heat from Jupiter's hot interior to the cooler polar regions,
much as winds and ocean currents are driven on Earth, from equator to
poles.  But temperature differences do not fully explain wind velocities
that can reach 265 mph.  An alternative theory is that pressure differences,
due to changes in the thermodynamic state of hydrogen at high and low
temperatures, set up the wind jets.

     Jupiter's rapid rotation rate is thought to have effects on wind velocity
and to produce some of Jupiter's bizarre circulation patterns, including
many spiral features.  These rotational effects are known as
manifestations of the Coriolis force.  Coriolis force is what determines the
spin direction of weather systems.  It basically means that on the surface
of a sphere (a planet), a parcel of gas farther from the poles has a higher
rotational velocity around the planet than a parcel closer to the poles.  As
gases then move north or south, interacting parcels with different
velocities produce vortices (whirlpools).  This may account for some of
Jupiter's circular surface features.

     Jupiter spins faster than any planet in the solar system.  Though 11 times
Earth's diameter, Jupiter spins more than twice as fast (once in 10 hours),
giving gases on the surface extremely high rates of travel -- 22,000 mph at
the equator, compared with 1000 mph for air at Earth's equator.  Jupiter's
rapid spin also causes this gas and liquid planet to flatten markedly at the
poles and bulge at the equator.

     Visible at the top of Jupiter's atmosphere are eye-catching features
such as the famous Great Red Spot and the exotic White Ovals, Brown
Barges and White Plumes.  The Great Red Spot, which is 25,000 miles wide
and large enough to swallow three Earths, is an enormous oval eddy of
swirling gases.  It is driven by two counter-flowing jet streams, which
pass, one on each side of it, moving in opposite directions, each with speeds
of 100-200 mph.  The Great Red Spot was first discovered in 1664, by the
British scientist Roger Hook, using Galileo's telescope.  In the three
centuries since, the  huge vortex has remained constant in latitude in
Jupiter's southern equatorial belt.  Because of its stable position,
astronomers once thought it might be a volcano.

     Another past theory compared the Great Red Spot to a gigantic hurricane. 
However, the GRS rotates anti-cyclonically while hurricanes are cyclonic
features (counterclockwise in the northern hemisphere, clockwise in the
southern) -- and the dynamics of the Great Red Spot appear unrelated to
moisture.

     The Great Red Spot most closely resembles an enormous tornado, a huge
vortex that sucks in smaller vortices.  The Coriolis effect  created by
Jupiter's fast spin, appears to be the key to the dynamics that drive the
spot.

     The source of the Great Red Spot's color remains a mystery.  Many
scientists now believe it to be caused by phosphorus, but its spectral line
does not quite match that of phosphorus.  The GRS may be the largest in a
whole array of spiral phenomena with similar dynamics.  About a dozen
white ovals, circulation patterns resembling the GRS, exist in the southern
latitudes of Jupiter and appear to be driven by the same forces.  Scientists
do not know why these ovals are white.

     Scientists believe the brown barges, which appear like dark patches on
the planet, are holes in the upper clouds, through which the reddish-brown
lower cloud layer may be glimpsed.  The equatorial plumes, or white
plumes, may be a type of wispy cirrus anvil cloud.

GALILEO MANAGEMENT

     The Galileo Project is managed for NASA's Office of Space Science and
Applications by the NASA Jet Propulsion Laboratory, Pasadena, Calif.  This
responsibility includes designing, building, testing, operating and tracking
Galileo.  NASA's Ames Research Center, Moffett Field, Calif. is responsible
for the atmosphere probe, which was built by Hughes Aircraft Company, El
Segundo, Calif.

     The probe project and science teams will be stationed at Ames during
pre-mission, mission operations, and data reduction periods.  Team
members will be at Jet Propulsion Laboratory for probe entry.

     The Federal Republic of Germany has furnished the orbiter's
retropropulsion module and is participating in the scientific investigations. 
The radioisotope thermoelectric generators were designed and built for the
U.S.  Department of Energy by the General Electric Company.

STS-34 INERTIAL UPPER STAGE (IUS-19)

     The Inertial Upper Stage (IUS) will again be used with the Space Shuttle,
this time to transport NASA's Galileo spacecraft out of Earth's orbit to
Jupiter, a 2.5-billion-mile journey.       

     The IUS has been used previously to place three Tracking and Data Relay
Satellites in geostationary orbit as well as to inject the Magellan
spacecraft into its interplanetary trajectory to Venus.  In addition, the IUS
has been selected by the agency for the Ulysses solar polar orbit mission.

     After 2 1/2 years of competition, Boeing Aerospace Co., Seattle, was
selected in August 1976 to begin preliminary design of the IUS.  The IUS
was developed and built under contract to the Air Force Systems Command's
Space Systems Division.  The Space Systems Division is executive agent for
all Department of Defense activities pertaining to the Space Shuttle
system.  NASA, through the Marshall Space Flight Center, Huntsville, Ala.,
purchases the IUS through the Air Force and manages the integration
activities of the upper stage to NASA spacecraft. 

Specifications

     IUS-19, to be used on mission STS-34, is a two-stage vehicle weighing
approximately 32,500 lbs.  Each stage has a solid rocket motor (SRM),
preferred over liquid-fueled engines because of SRM's relative simplicity,
high reliability, low cost and safety.

     The IUS is 17 ft. long and 9.25 ft. in diameter.  It consists of an aft
skirt, an aft stage SRM generating approximately 42,000 lbs. of thrust, an
interstage, a forward-stage SRM generating approximately 18,000 lbs. of
thrust, and an equipment support section.       

Airborne Support Equipment

     The IUS Airborne Support Equipment (ASE) is the mechanical, avionics
and structural equipment located in the orbiter.  The ASE supports the IUS
and the Galileo in the orbiter payload bay and elevates the combination for
final checkout and deployment from the orbiter.

     The IUS ASE consists of the structure, electromechanical mechanisms,
batteries, electronics and cabling to support the Galileo/IUS.  These ASE
subsystems enable the deployment of the combined vehicle; provide,
distribute and/or control electrical power to the IUS and spacecraft;
provide plumbing to cool the radioisotope thermoelectric generator (RTG)
aboard Galileo; and serve as communication paths between the IUS and/or
spacecraft and the orbiter.

IUS Structure

     The IUS structure is capable of supporting loads generated internally and
also by the cantilevered spacecraft during orbiter operations and the IUS
free flight.  It is made of aluminum skin-stringer construction, with
longerons and ring frames.      

Equipment Support Section 

     The top of the equipment support section contains the spacecraft
interface mounting ring and electrical interface connector segment for
mating and integrating the spacecraft with the IUS.  Thermal isolation is
provided by a multilayer insulation blanket across the interface between
the IUS and Galileo.

     The equipment support section also contains the avionics which provide
guidance, navigation, control, telemetry, command and data management,
reaction control and electrical power.  All mission-critical components of
the avionics system, along with thrust vector actuators, reaction control
thrusters, motor igniter and pyrotechnic stage separation equipment are
redundant to assure reliability of better than 98 percent.

IUS Avionics Subsystems

     The avionics subsystems consist of the telemetry, tracking and
command subsystems; guidance and navigation subsystem; data
management; thrust vector control; and electrical power subsystems. 
These subsystems include all the electronic and electrical hardware used to
perform all computations, signal conditioning, data processing and
formatting associated with navigation, guidance, control, data and
redundancy management.  The IUS avionics subsystems also provide the
equipment for communications between the orbiter and ground stations as
well as electrical power distribution.

     Attitude control in response to guidance commands is provided by thrust
vectoring during powered flight and by reaction control thrusters while
coasting.  Attitude is compared with guidance commands to generate error
signals.  During solid motor firing, these commands gimble the IUS's
movable nozzle to provide the desired pitch and yaw control.  The IUS's roll
axis thrusters maintain roll control.  While coasting, the error signals are
processed in the computer to generate thruster commands to maintain the
vehicle's altitude or to maneuver the vehicle.  

     The IUS electrical power subsystem consists of avionics batteries, IUS
power distribution units, a power transfer unit, utility batteries, a
pyrotechnic switching unit, an IUS wiring harness and umbilical and staging
connectors.  The IUS avionics system provides 5-volt electrical power to
the Galileo/IUS interface connector for use by the spacecraft telemetry
system.

IUS Solid Rocket Motors

     The IUS two-stage vehicle uses a large solid rocket motor and a small
solid rocket motor.  These motors employ movable nozzles for thrust vector
control.  The nozzles provide up to 4 degrees of steering on the large motor
and 7 degrees on the small motor.  The large motor is the longest-thrusting
duration SRM ever developed for space, with the capability to thrust as long
as 150 seconds.  Mission requirements and constraints (such as weight) can
be met by tailoring the amount of propellant carried.  The IUS-19
first-stage motor will carry 21,488 lb. of propellant; the second stage
6,067 lb.        

Reaction Control System 

     The reaction control system controls the Galileo/IUS spacecraft attitude
during coasting, roll control during SRM thrustings, velocity impulses for
accurate orbit injection and the final collision-avoidance maneuver after
separation from the Galileo spacecraft.  

     As a minimum, the IUS includes one reaction control fuel tank with a
capacity of 120 lb. of hydrazine.  Production options are available to add a
second or third tank.  However, IUS-19 will require only one tank.

IUS To Spacecraft Interfaces

     Galileo is physically attached to the IUS at eight attachment points,
providing substantial load-carrying capability while minimizing the
transfer of heat across the connecting points.   Power, command and data
transmission between the two are provided by several IUS interface
connectors.   In addition, the IUS provides a multilayer insulation blanket of
aluminized Kapton with polyester net spacers across the Galileo/IUS
interface, along with an aluminized Beta cloth outer layer.  All IUS thermal
blankets are vented toward and into the IUS cavity, which in turn is vented
to the orbiter payload bay.  There is no gas flow between the spacecraft and
the IUS.  The thermal blankets are grounded to the IUS structure to prevent
electrostatic charge buildup.

Flight Sequence

     After the orbiter payload bay doors are opened in orbit, the orbiter will
maintain a preselected attitude to keep the payload within thermal
requirements and constraints. 

     On-orbit predeployment checkout begins, followed by an IUS command link
check and spacecraft communications command check.  Orbiter trim
maneuvers are normally performed at this time.  

     Forward payload restraints will be released and the aft frame of the
airborne-support equipment will tilt the Galileo/IUS to 29 degrees.  This
will extend the payload into space just outside the orbiter payload bay,
allowing direct communication with Earth during systems checkout.  The
orbiter then will be maneuvered to the deployment attitude.  If a problem
has developed within the spacecraft or IUS, the IUS and its payload can be
restowed.

     Prior to deployment, the spacecraft electrical power source will be
switched from orbiter power to IUS internal power by the orbiter flight
crew.  After verifying that the spacecraft is on IUS internal power and that
all Galileo/IUS predeployment operations have been successfully completed,
a GO/NO-GO decision for deployment will be sent to the crew from ground
support.

     When the orbiter flight crew is given a "Go" decision, they will activate
the ordnance that separates the spacecraft's umbilical cables.  The crew
then will command the electromechanical tilt actuator to raise the tilt
table to a 58-degree deployment position.  The orbiter's RCS thrusters will
be inhibited and an ordnance-separation device initiated to physically
separate the IUS/spacecraft combination from the tilt table.

     Six hours, 20 minutes into the mission, compressed springs provide the
force to jettison the IUS/Galileo from the orbiter payload bay at
approximately 6 inches per second.  The deployment is normally performed
in the shadow of the orbiter or in Earth eclipse.  

     The tilt table then will be lowered to minus 6 degrees after IUS and its
spacecraft are deployed.  A small orbiter maneuver is made to back away
from IUS/Galileo.  Approximately 15 minutes after deployment, the
orbiter's OMS engines will be ignited to move the orbiter away from its
released payload.

     After deployment, the IUS/Galileo is controlled by the IUS onboard
computers.  Approximately 10 minutes after IUS/Galileo deployment from
the orbiter, the IUS onboard computer will send out signals used by the IUS
and/or Galileo to begin mission sequence events.  This signal will also
enable the IUS reaction control system.  All subsequent operations will be
sequenced by the IUS computer, from transfer orbit injection through
spacecraft separation and IUS deactivation. 

     After the RCS has been activated, the IUS will maneuver to the required
thermal attitude and perform any required spacecraft thermal control
maneuvers.

     At approximately 45 minutes after deployment from the orbiter, the
ordnance inhibits for the first SRM will be removed.  The belly of the
orbiter already will have been oriented towards the IUS/Galileo to protect
orbiter windows from the IUS's plume.  The IUS will recompute the first
ignition time and maneuvers necessary to attain the proper attitude for the
first thrusting period.  When the proper transfer orbit opportunity is
reached, the IUS computer will send the signal to ignite the first stage
motor 60 minutes after deployment.  After firing approximately 150
seconds, the IUS first stage will have expended its propellant and will be
separated from the IUS second stage.

     Approximately 140 seconds after first-stage burnout, the second- stage
motor will be ignited, thrusting about 108 seconds.   The IUS second stage
then will separate and perform a final collision/contamination avoidance
maneuver before deactivating.

SHUTTLE SOLAR BACKSCATTER ULTRAVIOLET INSTRUMENT

     The Shuttle Solar Backscatter Ultraviolet (SSBUV) instrument was
developed by NASA to calibrate similar ozone measuring space-based
instruments on the National Oceanic and Atmospheric Administration's
TIROS satellites (NOAA-9 and -11).

     The SSBUV will help scientists solve the problem of data reliability
caused by calibration drift of solar backscatter ultraviolet (SBUV)
instruments on orbiting spacecraft.  The SSBUV uses the Space Shuttle's
orbital flight path to assess instrument performance by directly comparing
data from identical instruments aboard the TIROS spacecraft, as the
Shuttle and the satellite pass over the same Earth location within a 1-hour
window.  These orbital coincidences can occur 17 times per day.

     The SBUV measures the amount and height distribution of ozone in the
upper atmosphere.  It does this by measuring incident solar ultraviolet
radiation and ultraviolet radiation backscattered from the Earth's
atmosphere.  The SBUV measures these parameters in 12 discrete
wavelength channels in the ultraviolet.  Because ozone absorbs in the
ultraviolet, an ozone measurement can be derived from the ratio of
backscatter radiation at different wavelengths, providing an index of the
vertical distribution of ozone in the atmosphere.

     Global concern over the depletion of the ozone layer has sparked
increased emphasis on developing and improving ozone measurement
methods and instruments.  Accurate, reliable measurements from space are
critical to the detection of ozone trends and for assessing the potential
effects and development of corrective measures.

     The SSBUV missions are so important to the support of Earth science
that six additional missions have been added to the Shuttle manifest for
calibrating ozone instruments on future TIROS satellites.  In addition, the
dates of the four previously manifested SSBUV flights have been
accelerated.

     The SSBUV instrument and its dedicated electronics, power, data and
command systems are mounted in the Shuttle's payload bay in two Get Away 
Special canisters, an instrument canister and a support canister.  Together,
they weigh approximately 1200 lb.   The instrument canister holds the
SSBUV, its specially designed aspect sensors and in-flight calibration
system.  A motorized door assembly opens the canister to allow the SSBUV
to view the sun and Earth and closes during the in-flight calibration
sequence.

     The support canister contains the power system, data storage and
command decoders.  The dedicated power system can operate the SSBUV for
a total of approximately 40 hours.

     The SSBUV is managed by NASA's Goddard Space Flight Center, Greenbelt,
Md.  Ernest Hilsenrath is the principal investigator.

GROWTH HORMONE CONCENTRATIONS AND DISTRIBUTION IN PLANTS

     The Growth Hormone Concentration and Distribution in Plants (GHCD)
experiment is designed to determine the effects of microgravity on the
concentration, turnover properties, and behavior of the plant growth
hormone, Auxin, in corn shoot tissue (Zea Mays).

     Mounted in foam blocks inside two standard middeck lockers, the
equipment consists of four plant cannisters, two gaseous nitrogen freezers
and two temperature recorders.  Equipment for the experiment, excluding
the lockers, weighs 97.5 pounds.

     A total of 228 specimens (Zea Mays seeds) are "planted" in special
filter, paper-Teflon tube holders no more than 56 hours prior to flight.  The
seeds remain in total darkness throughout the mission.

     The GHCD experiment equipment and specimens will be prepared in a
Payload Processing Facility at KSC and placed in the middeck lockers.  The
GHCD lockers will be installed in the orbiter middeck within the last 14
hours before launch.

     No sooner than 72 hours after launch, mission specialist Ellen Baker will
place two of the plant cannisters into the gaseous nitrogen freezers to
arrest the plant growth and preserve the specimens.  The payload will be
restowed in the lockers for the remainder of the mission.

     After landing, the payload must be removed from the orbiter within 2
hours and will be returned to customer representatives at the landing site. 
The specimens will be examined post flight for microgravity effects.

      The GHCD experiment is sponsored by NASA Headquarters, the Johnson
Space Center and Michigan State University.

POLYMER MORPHOLOGY

     The Polymer Morphology (PM) experiment is a 3M-developed organic
materials processing experiment designed to explore the effects of
microgravity on polymeric materials as they are processed in space. 

     Since melt processing is one of the more industrially significant
methods for making products from polymers, it has been chosen for study in
the PM experiment.  Key aspects of melt processing include polymerization,
crystallization and phase separation.  Each aspect will be examined in the
experiment.  The polymeric systems for the first flight of PM include
polyethelyne, nylon-6 and polymer blends.

     The apparatus for the experiment includes a Fournier transform infrared
(FTIR) spectrometer, an automatic sample manipulating system and a
process control and data acquisition computer known as the Generic
Electronics Module (GEM).  The experiment is contained in two separate,
hermetically sealed containers that are mounted in the middeck of the
orbiter.  Each container includes an integral heat exchanger that transfers
heat from the interior of the containers to the orbiter's environment.  All
sample materials are kept in triple containers for the safety of the
astronauts.

     The PM experiment weighs approximately 200 lb., occupies three
standard middeck locker spaces (6 cubic ft., total) in the orbiter and
requires 240 watts to operate.

     Mission specialists Franklin R. Chang-Diaz and Shannon W. Lucid are
responsible for the operation of the PM experiment on orbit.  Their interface
with the PM experiment is through a small, NASA-supplied laptop computer
that is used as an input and output device for the main PM computer.  This
interface has been programmed by 3M engineers to manage and display the
large quantity of data that is available to the crew.  The astronauts will
have an active role in the operation of the experiment.

     In the PM experiment, infrared spectra (400 to 5000 cm-1) will be
acquired from the FTIR by the GEM computer once every 3.2 seconds as the
materials are processed on orbit.  During the 100 hours of processing time,
approximately 2 gigabytes of data will be collected.  Post flight, 3M
scientists will process the data to reveal the effects of microgravity on
the samples processed in space.

     The PM experiment is unique among material processing experiments in
that measurements characterizing the effects of microgravity will be made
in real time, as the materials are processed in space.  

     In most materials processing space experiments, the materials have
been processed in space with little or no measurements made during
on-orbit processing and the effects of microgravity determined post facto.

     The samples of polymeric materials being studied in the PM experiment
are thin films (25 microns or less) approximately 25 mm in diameter.  The
samples are mounted between two infrared transparent windows in a
specially designed infrared cell that provides the capability of  thermally
processing the samples to 200 degrees Celsius with a high degree of
thermal control.  The samples are mounted on a carousel that allows them
to be positioned, one at a time, in the infrared beam where spectra may be
acquired.  The GEM provides all carousel and sample cell control.  The first
flight of PM will contain 17 samples.

     The PM experiment is being conducted by 3M's Space Research and
Applications Laboratory.  Dr. Earl L. Cook is 3M's Payload Representative and
Mission Coordinator.  Dr. Debra L. Wilfong is  PM's Science Coordinator, and
James E. Steffen is the Hardware Coordinator.  

     The PM experiment, a commercial development payload, is sponsored by
NASA's Office of Commercial Programs.  The PM experiment will be 3M's
fifth space experiment and the first under the company's 10-year Joint
Endeavor Agreement with NASA for 62 flight experiment opportunities. 
Previous 3M space experiments have studied organic crystal growth from
solution (DMOS/1 on mission STS 51-A and DMOS/2 on STS 61-B) and
organic thin film growth by physical vapor treatment (PVTOS/1 on STS 51-I
and PVTOS/2 on mission STS-26).

STUDENT EXPERIMENT

Zero Gravity Growth of Ice Crystals From Supercooled Water With Relation
To Temperature (SE82-15)

     This experiment, proposed by Tracy L. Peters, formerly of Ygnacio High
School, Concord, Calif., will observe the geometric ice crystal shapes
formed at supercooled temperatures, below 0 degrees Celsius, without the
influence of gravity.  

     Liquid water has been discovered at temperatures far below water's
freezing point.  This phonomenon occurs because liquid water does not have
a nucleus, or core, around which to form the crystal.  When the ice freezes
at supercold temperatures, the ice takes on many geometric shapes based
on the hexagon.  The shape of the crystal primarily depends on the
supercooled temperature and saturation of water vapor.  The shapes of
crystals vary from simple plates to complex prismatic crystals.

     Many scientists have tried to determine the relation between
temperature and geometry, but gravity has deformed crystals, caused
convection currents in temperature-controlled apparatus, and caused faults
in the crystalline structure.  These all affect crystal growth by either rapid
fluctuations of temperature or gravitational influence of the crystal
geometry.  

     The results of this experiment could aid in the design of radiator cooling
and cryogenic systems and in the understanding of high-altitude
meteorology and planetary ring structure theories.

     Peters is now studying physics at the University of California at Berkeley.
His teacher advisor is James R. Cobb, Ygnacio High School; his sponsor is
Boeing Aerospace Corp., Seattle.

     Peters also was honored as the first four-time NASA award winner at the
International Science and Engineering Fair (ISEF), which recognizes
student's creative scientific endeavors in aerospace research.  At the 1982
ISEF, Peters was one of two recipients of the Glen T. Seaborg Nobel Prize
Visit Award, an all-expense-paid visit to Stockholm to attend the Nobel
Prize ceremonies, for his project "Penetration and Diffusion of Supersonic
Fluid."

MESOSCALE LIGHTNING EXPERIMENT

     The Space Shuttle will again carry the Mesoscale Lightning Experiment
(MLE), designed to obtain nighttime images of lightning in order to better
understand the global distribution of lightning, the interrelationships
between lightning events in nearby storms, and relationships between
lightning, convective storms and precipitation.  

     A better understanding of the relationships between lightning and
thunderstorm characteristics can lead to the development of applications in
severe storm warning and forecasting, and early warning systems for
lightning threats to life and property.

     In recent years, NASA has used both Space Shuttle missions and
high-altitude U-2 aircraft to observe lightning from above convective
storms.  The objectives of these observations have been to determine some
of the baseline design requirements for a satellite-borne optical lightning
mapper sensor; study the overall optical and electrical characteristics of
lightning as viewed from above the cloudtop; and investigate the
relationship between storm electrical development and the structure,
dynamics and evolution of thunderstorms and thunderstorm systems.

     The MLE began as an experiment to demonstrate that meaningful,
qualitative observations of lightning could be made from the Shuttle. 
Having accomplished this, the experiment is now focusing on quantitative
measurements of lightning characteristics and observation simulations for
future space-based lightning sensors.

     Data from the MLE will provide information for the development of
observation simulations for an upcoming polar platform and Space Station
instrument, the Lightning Imaging Sensor (LIS).  The lightning experiment
also will be helpful for designing procedures for using the Lightning Mapper
Sensor (LMS), planned for several geostationary platforms.

     In this experiment, Atlantis'  payload bay camera will be pointed
directly below the orbiter to observe nighttime lightning in large, or
mesoscale, storm systems to gather global estimates of lightning as
observed from Shuttle altitudes.  Scientists on the ground will analyze the
imagery for the frequency of lightning flashes in active storm clouds
within the camera's field of view, the length of lightning discharges, and
cloud brightness when illuminated by the lightning discharge within the
cloud. 

     If time permits during missions, astronauts also will use a handheld
35mm camera to photograph lightning activity in storm systems not
directly below the Shuttle's orbital track.

     Data from the MLE will be associated with ongoing observations of
lightning made at several locations on the ground, including observations
made at facilities at the Marshall Space Flight Center, Huntsville, Ala.;
Kennedy Space Center, Fla.; and the NOAA Severe Storms Laboratory,
Norman, Okla.  Other ground-based lightning detection systems in Australia,
South America and Africa will be intergrated when possible.

     The MLE is managed by the Marshall Space Flight Center.  Otha H. Vaughan
Jr., is coordinating the experiment.  Dr. Hugh Christian is the project
scientist, and Dr. James Arnold is the project manager.

IMAX

     The IMAX project is a collaboration between NASA and the Smithsonian
Institution's National Air and Space Museum to document significant space
activities using the IMAX film medium.  This system, developed by the IMAX
Systems Corp., Toronto, Canada, uses specially designed 70mm film
cameras and projectors to record and display very high definition
large-screen color motion pictures.

     IMAX cameras previously have flown on Space Shuttle missions 41-C,
41-D and 41-G to document crew operations in the payload bay and the
orbiter's middeck and flight deck along with spectacular views of space and
Earth.  

     Film from those missions form the basis for the IMAX production, "The
Dream is Alive."  On STS 61-B, an IMAX camera mounted in the payload bay
recorded extravehicular activities in the EAS/ACCESS space construction
demonstrations.

     The IMAX camera, most recently carried aboard STS-29, will be used on
this mission to cover the deployment of the Galileo spacecraft and to
gather material on the use of observations of the Earth from space for
future IMAX films.

AIR FORCE MAUI OPTICAL SITE CALIBRATION TEST

     The Air Force Maui Optical Site (AMOS) tests allow ground-based
electro-optical sensors located on Mt. Haleakala, Maui, Hawaii, to collect
imagery and signature data of the orbiter during cooperative overflights. 
Scientific observations made of the orbiter while performing Reaction
Control System thruster firings, water dumps or payload bay light
activation are used to support the calibration of the AMOS sensors and the
validation of spacecraft contamination models.  AMOS tests have no
payload-unique flight hardware and only require that the orbiter be in
predefined attitude operations and lighting conditions.

     The AMOS facility was developed by Air Force Systems Command (AFSC)
through its Rome Air Development Center, Griffiss Air Force Base, N.Y., and
is administered and operated by the AVCO Everett Research Laboratory,
Maui.  The principal investigator for the AMOS tests on the Space Shuttle is
from AFSC's Air Force Geophysics Laboratory, Hanscom Air Force Base,
Mass.  A co-principal investigator is from AVCO.

     Flight planning and mission support activities for the AMOS test
opportunities are provided by a detachment of AFSC's Space Systems
Division at Johnson Space Center, Houston.  Flight operations are conducted
at JSC Mission Control Center in coordination with the AMOS facilities
located in Hawaii.

SENSOR TECHNOLOGY EXPERIMENT

     The Sensor Technology Experiment (STEX) is a radiation detection
experiment designed to measure the natural radiation background.  The STEX
is a self-contained experiment with its own power, sensor, computer
control and data storage.  A calibration pack, composed of a small number
of passive threshold reaction monitors, is attached to the outside of the
STEX package.

     Sponsored by the Strategic Defense Initiative Organization, the STEX
package weighs approximately 50 pounds and is stowed in a standard
middeck locker throughout the flight.

PAYLOAD AND VEHICLE WEIGHTS

     Vehicle/Payload	                              Weight (Pounds)
     Orbiter (Atlantis) Empty				172,018
     Galileo/IUS (payload bay)				 43,980
     Galileo support hardware  (middeck)		     59
     SSBUV (payload bay)				    637
     SSBUV support					    578
     DSO						     49
     DTO						    170
     GHCD						    130
     IMAX						    269
     MLE						     15
     PM							    219
     SSIP						     70
     STEX						     52
     Orbiter and Cargo at SRB Ignition			264,775
     Total Vehicle at SRB Ignition		      4,523,810
     Orbiter Landing Weight				195,283

SPACEFLIGHT TRACKING AND DATA NETWORK

     Primary communications for most activities on STS-34 will be
conducted through the orbiting Tracking and Data Relay Satellite System
(TDRSS), a constellation of three communications satellites in
geosynchronous orbit 22,300 miles above the Earth.  In addition, three NASA
Spaceflight Tracking and Data Network (STDN) ground stations and the NASA
Communications Network (NASCOM), both managed by Goddard Space Flight
Center, Greenbelt, Md., will play key roles in the mission.

     Three stations -- Merritt Island and Ponce de Leon, Florida and the
Bermuda -- serve as the primary communications during the launch and
ascent phases of the mission.  For the first 80 seconds, all voice, telemetry
and other communications from the Space Shuttle are relayed to the
mission managers at Kennedy and Johnson Space Centers by way of the
Merritt Island facility.

     At 80 seconds, the communications are picked up from the Shuttle and
relayed to the two NASA centers from the Ponce de Leon facility, 30 miles
north of the launch pad.  This facility provides the communications between
the Shuttle and the centers for 70 seconds, or until 150 seconds into the
mission.  This is during a critical period when exhaust from the solid rocket
motors "blocks out" the Merritt Island antennas.

     The Merritt Island facility resumes communications to and from the
Shuttle after those 70 seconds and maintains them until 6 minutes, 30
seconds after launch when communications are "switched over" to Bermuda. 
Bermuda then provides the communications until 11 minutes after liftoff
when the TDRS-East satellite acquires the Shuttle.  TDRS-West acquires
the orbiter at launch plus 50 minutes.

     The TDRS-East and -West satellites will provide communications with
the Shuttle during 85 percent or better of each orbit.  The TDRS-West
satellite will handle communications with the Shuttle during its descent
and landing phases.

CREW BIOGRAPHIES

     Donald E. Williams, 47, Capt., USN, will serve as commander.  Selected as
an astronaut in January 1978, he was born in Lafayette, Ind.

     Williams was pilot for STS-51D, the fourth flight of Discovery, launched
April 12, 1985.  During the mission, the seven-member crew deployed the
Anik-C communications satellite for Telesat of Canada and the  Syncom
IV-3 satellite for the U.S. Navy.  A malfunction in the Syncom spacecraft
resulted in the first unscheduled extravehicular, rendezvous and proximity
operation for the Space Shuttle in an attempt to activate the satellite.

     He graduated from Otterbein High School, Otterbein, Ind., in 1960 and
received his B.S. degree in mechanical engineering from Purdue University
in 1964.  Williams completed his flight training at Pensacola, Fla.,
Meridian, Miss., and Kingsville, Texas, and earned his wings in 1966.

     During the Vietnam Conflict, Williams completed 330 combat missions. 
He has logged more than 5,400 hours flying time, including 5,100 in jets,
and 745 aircraft carrier landings.

     Michael J. McCulley, 46, Cdr., USN, will be pilot on this flight. Born in
San Diego, McCulley considers Livingston, Tenn., his hometown.  He was
selected as a NASA astronaut in 1984.  He is making his first Space Shuttle
flight.

     McCulley graduated from Livingston Academy in 1961.  He received B.S.
and M.S. degrees in metallurgical engineering from Purdue University in
1970.

     After graduating from high school, McCulley enlisted in the U.S. Navy and
subsequently served on one diesel-powered and two nuclear-powered
submarines.  Following flight training, he served tours of duty in A-4 and
A-65 aircraft and was selected to attend the Empire Test Pilots School in
Great Britain.  He served in a variety of test pilot billets at the Naval Air
Test Center, Patuxent River, Md., before returning to sea duty on the USS
Saratoga and USS Nimitz.

     He has flown more than 50 types of aircraft, logging more than 4,760
hours, and has almost 400 carrier landings on six aircraft carriers.

     Shannon W. Lucid, 46, will serve as mission specialist (MS-1) on this,
her second Shuttle flight.  Born in Shanghai, China, she considers Bethany,
Okla., her hometown.  Lucid is a member of the astronaut class of 1978.

     Lucid's first Shuttle mission was during STS 51-G, launched from the
Kennedy Space Center on June 17, 1985.  During that flight, the crew
deployed communications satellites for Mexico, the Arab League and the
United States.

     Lucid graduated from Bethany High School in 1960.  She then attended
the University of Oklahoma where she received a B.S. degree in chemistry in
1963, an M.S. degree in biochemistry in 1970 and a Ph.D. in biochemistry in
1973.

     Before joining NASA, Lucid held a variety of academic assignments such
as teaching assistant at the University of Oklahoma's department of
chemistry; senior laboratory technician at the Oklahoma Medical Research
Foundation; chemist at Kerr-McGee in Oklahoma City; graduate assistant in
the University of Oklahoma Health Science Center's department of
biochemistry; and molecular biology and research associate with the
Oklahoma Medical Research Foundation in Oklahoma City.  Lucid also is a
commercial, instrument and multi-engine rated pilot.

     Franklin Chang-Diaz, 39, will serve as MS-2.  Born in San Jose, Costa
Rica, Chang-Diaz also will be making his second flight since being selected
as an astronaut in 1980.

     Chang-Diaz made his first flight aboard Columbia on mission STS 61-C, 
launched from KSC Jan. 12, 1986.  During the 6-day flight he participated in
the deployment of the SATCOM KU satellite, conducted experiments in
astrophysics and operated the materials science laboratory, MSL-2.

     Chang-Diaz graduated from Colegio De La Salle, San Jose, Costa Rica, in
1967, and from Hartford High School, Hartford, Conn., in 1969.  He received
a B.S. degree in mechanical engineering from the University of Connecticut
in 1973 and a Ph.D. in applied plasma physics from the Massachusetts
Institute of Technology in 1977.

     While attending the University of Connecticut, Chang-Diaz also worked
as a research assistant in the physics department and participated in the
design and construction of high-energy atomic collision experiments.  Upon
entering graduate school at MIT, he became heavily involved in the United
State's controlled fusion program and conducted intensive research in the
design and operation of fusion reactors.  In 1979, he developed a novel
concept to guide and target fuel pellets in an inertial fusion reactor
chamber.  In 1983, he was appointed as visiting scientist with the MIT
Plasma Fusion Center which he visits periodically to continue his research
on advanced plasma rockets.

     Chang-Diaz has logged more than 1,500 hours of flight time, including
1,300 hours in jet aircraft.

     Ellen S. Baker, 36, will serve as MS-3.  She will be making her first
Shuttle flight.  Baker was born in Fayetteville, N.C., and was selected as an
astronaut in 1984.

     Baker graduated from Bayside High School, New York, N.Y., in 1970.  She
received a B.A. degree in geology from the State University of New York at
Buffalo in 1974, and an M.D. from Cornell University in 1978.

     After medical school, Baker trained in internal medicine at the
University of Texas Health Science Center in San Antonio, Texas.  In 1981,
she was certified by the American Board of Internal Medicine.

     Baker joined NASA as a medical officer at the Johnson Space Center in
1981 after completing her residency.  That same year, she graduated with
honors from the Air Force Aerospace Medicine Primary Course at Brooks Air
Force Base in San Antonio.  Prior to her selection as an astronaut, she
served as a physician in the Flight Medicine Clinic at JSC.

NASA PROGRAM MANAGEMENT

NASA Headquarters
Washington, D.C.

Richard H. Truly
NASA Administrator

James R. Thompson Jr.
NASA Deputy Administrator

William B. Lenoir
Acting Associate Administrator for Space Flight

George W.S. Abbey
Deputy Associate Administrator for Space Flight

Arnold D. Aldrich
Director, National Space Transportation Program

Leonard S. Nicholson
Deputy Director, NSTS Program
(located at Johnson Space Center)

Robert L. Crippen
Deputy Director, NSTS Operations
(located at Kennedy Space Center)

David L. Winterhalter
Director, Systems Engineering and Analyses

Gary E. Krier
Director, Operations Utilization

Joseph B. Mahon
Deputy Associate Administrator
for Space Flight (Flight Systems)

Charles R. Gunn
Director, Unmanned Launch Vehicles
and Upper Stages

George A. Rodney
Associate Administrator for Safety, Reliability,
Maintainability and Quality Assurance

Charles T. Force
Associate Administrator for Operations

Dr. Lennard A. Fisk
Associate Administrator for Space Science
and Applications

Samuel Keller
Assistant Deputy Associate Administrator
NASA Headquarters

Al Diaz
Deputy Associate Administrator for
Space Science and Applications

Dr. Geoffrey A. Briggs
Director, Solar System Exploration Division

Robert F. Murray
Manager, Galileo Program

Dr. Joseph Boyce
Galileo Program Scientist

Johnson Space Center
Houston, Texas

Aaron Cohen
Director

Paul J. Weitz
Deputy Director

Richard A. Colonna
Manager, Orbiter and GFE Projects

Donald R. Puddy
Director, Flight Crew Operations

Eugene F. Kranz 
Director, Mission Operations

Henry O. Pohl
Director, Engineering

Charles S. Harlan
Director, Safety, Reliability and Quality Assurance

Kennedy Space Center
Florida

Forrest S. McCartney
Director

Thomas E. Utsman
Deputy Director

Jay F. Honeycutt
Director, Shuttle Management
and Operations

Robert B. Sieck
Launch Director

George T. Sasseen
Shuttle Engineering Director

Conrad G. Nagel
Atlantis Flow Director

James A. Thomas
Director, Safety, Reliability and
Quality Assurance

John T. Conway
Director, Payload Managerment
and Operations

Marshall Space Flight Center
Huntsville, Ala.

Thomas J. Lee
Director

Dr. J. Wayne Littles
Deputy Director

G. Porter Bridwell
Manager, Shuttle Projects Office

Dr. George F. McDonough
Director, Science and Engineering

Alexander A. McCool
Director, Safety, Reliability and Quality Assurance

Royce E. Mitchell
Manager, Solid Rocket Motor Project

Cary H. Rutland
Manager, Solid Rocket Booster Project

Jerry W. Smelser
Manager, Space Shuttle Main Engine Project

G. Porter Bridwell
Acting Manager, External Tank Project

Sidney P. Saucier
Manager, Space Systems Projects Office 
[for IUS]

Stennis Space Center
Bay St. Louis, Miss.

Roy S. Estess
Director

Gerald W. Smith
Deputy Director

William F. Taylor
Associate Director

J. Harry Guin
Director,  Propulsion Test Operations

Edward L. Tilton III
Director, Science and Technology Laboratory

John L. Gasery Jr.
Chief, Safety/Quality Assurance
and Occupational Health

Jet Propulsion Laboratory

Dr. Lew Allen
Director

Dr. Peter T. Lyman
Deputy Director

Gene Giberson
Laboratory Director for Flight Projects

John Casani
Assistant Laboratory Director for Flight Projects

Richard J. Spehalski
Manager, Galileo Project

William J. O'Neil
Manager, Science and Mission Design,
Galileo Project

Dr. Clayne M. Yeates
Deputy Manager, Science and Mission Design,
Galileo Project

Dr.  Torrence V Johnson
Galileo Project Scientist

Neal E. Ausman Jr.
Mission Operations and Engineering Manager
Galileo Project

A. Earl Cherniack
Orbiter Spacecraft Manager
Galileo Project

Matthew R. Landano
Deputy Orbiter Spacecraft Manager
Galileo Project

William G. Fawcett
Orbiter Science Payload Manager
Galileo Project

Ames Research Center
Mountain View, Calif.

Dr. Dale L. Compton
Acting Director

Dr. David Morrison
Director, Science Projects Directorate

Benny Chin
Probe Manager
Galileo Project

Lawrence Colin
Probe Scientist
Galileo Project

Richard E. Young
Probe Scientist
Galileo Project

Ames-Dryden Flight Research Facility
Edwards, Calif.

Martin A. Knutson
Site Manager

Theodore G. Ayers
Deputy Site Manager

Thomas C. McMurtry
Chief, Research Aircraft Operations Division

Larry C. Barnett
Chief, Shuttle Support Office

Goddard Space Flight Center
Greenbelt, Md

Dr. John W. Townsend
Director

Peter Burr
Director, Flight Projects

Dale L. Fahnestock
Director, Mission Operations and Data Systems

Daniel A. Spintman
Chief, Networks Division

Gary A. Morse
Network Director

Dr. Robert D. Hudson
Head, Atmospheric Chemistry and Dynamics

Ernest Hilsenrath
SSBUV Principal Investigator

Jon R. Busse
Director, Engineering Directorate

Robert C. Weaver Jr.
Chief, Special Payloads Division

Neal F. Barthelme
SSBUV Mission Manager