Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/STSKITS/STS_54.TXT

Text File | 1992-12-20 | 91KB | 1,930 lines

"6_2_2_42_2_13.TXT" (68385 bytes) was created on 12-17-92

NASA PRESS KIT STS-54



MEDIA SERVICES INFORMATION


NASA Select Television Transmission

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

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

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

Status Reports

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

        A mission press briefing schedule will be issued prior to launch.
During the mission, status briefings by a flight director or mission
operations representative and when appropriate, the science team will occur at
least once per day.  The updated NASA Select television schedule will indicate
when mission briefings are planned.






STS-54 QUICK LOOK


Launch Date/Site:       Jan. 13, 1993/Kennedy Space Center, Fla. -- Pad 39B

Launch Time:            8:52 a.m. EST

Orbiter:                Endeavour (OV-105) - 3rd Flight

Orbit/Inclination:      160 nm/28.45 degrees

Mission Duration:       5 days, 0 hours, 23 minutes, 32 seconds

Landing Time/Date:      8:34 a.m. EST, Jan. 19, 1993

Primary Landing Site:   Kennedy Space Center, Fla.

Abort Landing Sites     Return To Launch Site Abort:  KSC, Fla
                        TransAtlantic Abort Landing:  Banjul, The Gambia
                                                      Ben Guerir, Morroco
                                                      Moron, Spain
                        Abort-Once-Around:            Edwards AFB, Calif.
                                                      KSC/White Sands

Crew:                   John Casper - Commander
                        Don McMonagle - Pilot
                        Mario Runco, Jr. - MS1 (EV2)
                        Greg Harbaugh - MS2 (EV1)
                        Susan Helms - MS3

Cargo Bay Payloads:     Tracking and Data Relay Satellite-F
                        Diffuse X-ray Spectrometer

Middeck Payloads:       Commercial Generic Bioprocessing Apparatus
                        Chromosome and Plant Cell Division in Space Experiment

                        Physiological and Anatomical Rodent Experiment
                        Space Acceleration Measurement System
                        Solid Surface Combustion Experiment





STS-54 SUMMARY TIMELINE

Flight Day One

Launch/post insertion
TDRS-F deploy (nominal deploy is 6 hours, 13 minutes MET)
Separation burn (178 n.m. x 162 n.m. orbit)
DXS activation

Flight Day Two

DXS operations
Circularization burn (162 n.m. x 162 n.m. orbit)
CGBA operations
Medical DSOs

Flight Day Three

DXS operations
CGBA operations
SSCE operations
CHROMEX/PARE operations

Flight Day Four

DXS operations
CGBA operations
Medical DSOs
CHROMEX/PARE operations

Flight Day Five

DXS operations
EVA

Flight Day Six

Flight Control Systems checkout
Cabin stow

Flight Day Seven

Deorbit Preparation
Deorbit Burn
Entry
Landing


STS-54 VEHICLE AND PAYLOAD WEIGHTS

Vehicle/Payload                                         Pounds

Orbiter (Endeavour) Empty and three SSMEs              173,174

Tracking and Data Relay Satellite-F (TDRS-F)             5,586

Two-Stage Inertial Upper Stage (IUS)                    32,670

Diffuse X-ray Spectrometer (DXS)                         2,625

Medical Detailed Supplementary Objectives (DSOs)            34

Total Vehicle at Solid Rocket Booster Ignition       4,525,222

Orbiter Landing Weight                                 205,000







STS-54 ORBITAL EVENTS SUMMARY

Event           Elapsed time            Velocity change         Orbit
(nm)

Launch          0:00:00:00                      N/A             N/A

OMS-2           0:00:42:00                      221 fps         163x160

TDRS deploy     0:06:13:00                      N/A             163 x 160

Sep 1           0:06:14:00                      2.2 fps         162 x 160

OMS-3           0:06:28:00                      31 fps          178 x 162

OMS-4           1:02:09:00                      28 fps          162 x 161

Deorbit         5:22:32:00                      306 fps         N/A

Landing         5:23:32:00                      N/A             N/A


SPACE SHUTTLE ABORT MODES

        Space Shuttle launch abort philosophy aims toward a safe and intact
recovery of the flight crew, orbiter and its payload.  Abort modes include:

        * Abort-To-Orbit (ATO) -- Partial loss of main engine thrust late
enough to permit reaching a minimal 105-nautical mile orbit with orbital
maneuvering system engines.

        * Abort-Once-Around (AOA) -- Earlier main engine shutdown with the
capability to allow one orbit around before landing at either Edwards Air
Force Base, Calif., White Sands Space Harbor, N.M., or the Shuttle Landing
Facility (SLF) at the Kennedy Space Center, Fla.

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

        * Return-To-Launch-Site (RTLS) -- Early shutdown of one or more
engines, without enough energy to reach Banjul, would result in a pitch around
and thrust back toward KSC until within gliding distance of the Shuttle
Landing
Facility.

        STS-54 contingency landing sites are Edwards Air Force Base, the
Kennedy Space Center, White Sands Space Harbor, Banjul, Ben Guerir and Moron.

STS-54 PRELAUNCH PROCESSING

     Processing of Endeavour began with its landing at KSC after the STS-47
mission.  It was deserviced from its previous flight and prepared for the
upcoming STS-54 mission.  Endeavour spent a total of 64 calendar days in the
Orbiter Processing Facility.

     The Space Shuttle Endeavour was rolled out of the Vehicle Assembly
Building for Pad 39-B on Dec. 3.  The TDRS-F/IUS-13 was installed into the
orbiter's payload bay the following day.

     A standard 43-hour launch countdown is scheduled to begin 3 days prior to
launch.  During the countdown, the orbiter's fuel cell storage tanks and all
orbiter systems will be prepared for flight.

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

     Endeavour's end-of-mission landing is planned at Kennedy Space Center's
Shuttle Landing Facility. Endeavour's next flight, STS-57, targeted for May
1993, is a planned 7-day mission which will involve the SPACEHAB- 1 payload
and
the retrieval of the EURECA satellite.






TRACKING DATA RELAY SATELLITE-F (TDRS-F)

History

     The Tracking and Data Relay Satellite System (TDRSS) is a space- based
network that provides communications, tracking, telemetry, data acquisition
and command services essential to the Space Shuttle and low-Earth orbital
spacecraft missions.  All Shuttle missions and nearly all NASA spacecraft in
Earth orbit require TDRSS's support capabilities for mission success.

     The TDRSS was initiated following studies in the early 1970s which showed
that a system of telecommunications satellites, operated from a single ground
station, could better meet the requirements of NASA missions.  In addition,
the system was seen as a means of halting the spiralling costs of upgrading
and operating a network of tracking and communications ground stations located
around the world.

     The TDRSS has enabled NASA to cut telecommunications costs by as much as
60 percent while increased data acquisition and communications with
Earth-orbital spacecraft from 15 to 85 percent -- and in some cases to 100
percent -- depending on a spacecraft's orbital position.

     In addition to the Shuttle, TDRSS customers include the Compton Gamma Ray
Observatory, Upper Atmosphere Research Satellite, Hubble Space Telescope,
Cosmic Background Explorer, Extreme Utraviolet Explorer, TOPEX-Poseidon, both
Landsat spacecrafts and other non- NASA missions.  Among future
TDRSS-dependent missions are Space Station Freedom (SSF) and the Earth
Observation System (EOS).  It is estimated that over $70 billion in space
missions through the end of this decade are TDRSS-dependent.

     The TDRSS consists of two major elements: A constellation of three
geosynchronous satellites -- two operational and one in ready reserve -- and a
ground terminal located at White Sands, N.M. A second TDRSS ground terminal is
under development to eliminate a critical single point of failure.

     To meet the growing demand for communications capabilities for future
missions, such as SSF and the EOS, increased TDRSS capacity will be required
to meet these additional mission requirements.

Current Status

     The Tracking and Data Relay Satellite (TDRS-6) is the sixth in a series
of communications spacecraft planned for the TDRSS.

     TDRS-1, has exceeded its design life of 7 years and is continuing to
provide limited services.  TDRS-2 was lost in the Challenger accident.  TDRSs
3-5 are operating, but only two are fully functional.  In the event of a
malfunction of one of these fully operational TDRS, the absence of a third
fully operational satellite in ready reserve would severely impact orbiting
customers for nearly a year before an emergency replenishment launch could be
conducted.

     The successful launch and checkout of TDRS-6 will give NASA the essential
requirement of having two fully operational satellites and a fully operational
ready reserve capability.  This will assure that NASA communications,
telemetry and data acquisition capabilities required by space missions will
not be jeopardized.

     Following the successful launch and checkout of TDRS-6, the TDRSS
constellation will be reconfigured.  Because of the flexible capability of the
TDRSS, one TDRS spacecraft will provide service to the Compton Gamma Ray
Observatory (GRO), including realtime transmission of scientific data.  This
is required because of a problem with the GRO's tape recorders.  To
accommodate this activity, NASA will operate TDRS-1 thru an existing station
at Tidbinbilla, Australia, moving TDRS-1 from 171 degrees west longitude to 85
degrees east longitude (over the Indian Ocean south of Ceylon).

     Data from GRO will be relayed to the ground terminal at White Sands, via
an Intelsat satellite.  From White Sands, the data will be sent to the Goddard
Space Flight Center, Greenbelt, Md. Control of the TDRS spacecraft will remain
at White Sands.


TDRS SPACECRAFT LAUNCH AND OPERATIONAL STATUS

Spacecraft                      Mission                 Status

TDRS-1                  STS-6   April 5, 1983           Partially functional

TDRS-2                  STS-51L January 1986

TDRS-3                  STS-26  Sept. 29, 1988          Partially functional

TDRS-4                  STS-29  March 13, 1989          Fully functional

TDRS-5                  STS-43  August 2, 1991          Fully functional


TDRS SPACECRAFT CURRENT AND RECONFIGURED POSITION


Current Position

TDRS-1 171 degrees west (East of Gilbert Islands and South of Hawaii).

TDRS-3 62 degrees west

TDRS-4 41 degrees west (over the Atlantic Ocean off Brazil)

TDRS-5 174 degrees west (East of Gilbert Islands and South of Hawaii).


Reconfigured Position after TDRS-F (6 on orbit)

TDRS-1          85 degrees east

TDRS-3          171 degrees west

TDRS-4          41 degrees west

TDRS-5          174 degrees west

TDRS-6          62 degrees west


Deployment Sequence

     TDRS-6 will be deployed from Endeavour cargo bay approximately 6 hours
after launch on orbit 5 over the Pacific Ocean north of Hawaii. Injection burn
to geostationary orbit will be initiated at 77 degrees east longitude (Indian
Ocean, south of India), placing the satellite in orbit at 178 degrees west
longitude (over the Pacific near the Gilbert Islands).

     The STS-54 crew elevates the Inertial Upper Stage/TDRS (IUS/TDRS) to 29
degrees in the payload bay for preliminary tests and then raises it to 58
degrees for deployment.  A spring-loaded ejection system is used for deploying
the IUS/TDRS.

     The first burn of the IUS booster will take place 1 hour after deployment
or about 7 hours after STS-54 launch.  The IUS second and final burn, to
circularize the orbit, will take place 5.5 hours after the first burn,
approximately 12.5 hours into the mission.  Separation of the booster and
satellite will occur at 13 hours after launch.

     Upon reaching geostationary orbit, the deployment of TDRS appendages and
antennas is started.  The total time required for the deployment sequence is
8-9 hours:

        1 - Deploy solar arrays.
        2 - Deploy space-ground link boom.
        3 - Deploy C-band boom.
        4 - Separation of IUS and TDRS.
        5 - Release single access booms.
        6 - Position single access antennas.
        7 - Open single access antennas.

     During steps 5, 6 and 7, Earth acquisition is taking place concurrently.

     TDRS is three-axis stabilized with the multiple access body, fixed
antennas pointing constantly at the Earth while the solar arrays track the
sun.

Communication System

     TDRS satellites do not process customer traffic in either direction.
Rather, they operate as "bent pipe" repeaters, relaying signals and data
between the user spacecraft and the ground terminal and vice versa.

     Nominally, the TDRSS is intended to meet the requirements of up to 24
customer spacecraft, including the Space Shuttle, simultaneously.  It provides
two types of service: multiple access which can relay data from as many as 20
low data rate (100 bits per second to 50 kilobits per second) customer
satellites simultaneously and single access antennas which provide two high
data rate channels to 300 megabits per second from both the east and west
locations.

     The White Sands Ground Terminal (WSGT) provides a location with a clear
line-of-sight to the TDRSs and a place where rain conditions have limited
interference with the availability of the Ku-band uplink and downlink
channels. The WSGT is operated for NASA by GTE Government Systems Corp.,
Needham Heights, Mass.

     Co-located at White Sands is the NASA Ground Terminal operated by Bendix
Field Engineering Corp., Columbia, Md. This terminal provides the interface
between WSGT and other primary network elements located at NASA's Goddard
Space Flight Center, Md.

     Facilities at GSFC include the Network Control Center (NCC) which
provides system scheduling and is the focal point for NASA communications and
the WSGT and TDRSS users; the Flight Dynamics Facility which provides the
network with antenna pointing information for user spacecraft and the TDRSs
and the NASA Communications Network (NASCOM) which provides the common carrier
interface through Earth terminals at Goddard, White Sands and the Johnson
Space Center, Houston.

     The NCC console operators monitor network performances, schedule
emergency interfaces, isolate faults in the system, account for system use,
test the system and conduct simulations.

     The user services available from the space network are provided through
NASCOM, a global system providing operational communications support to all
NASA projects.  NASCOM offers voice, data and teletype links with the space
network, the Ground Spaceflight Tracking and Data Network and the user
spacecraft control centers.

     NASA's Office of Space Communications, Washington, D.C., has overall
management responsibility of these tracking, data acquisition and
communications facilities.

TDRS Components

     TDRSs are composed of three distinct modules -- an equipment module, a
communications payload module and an antenna module.  The modular design
reduces the cost of individual design and construction efforts that, in turn,
lower the cost of each satellite.

     The equipment module housing the subsystems that operate the satellite is
located in the lower hexagon of the spacecraft.  The attitude control
subsystem stabilizes the satellite to provide accurate antenna pointing and
proper orientation of the solar panels to the sun.  The electrical power
subsystems consists of two solar panels that provide a 10-year power supply of
approximately 1,700 watts.  The thermal control subsystem consists of surface
coatings and controlled electric heaters.

     The payload module is composed of the electronic equipment required to
provide communications between the user spacecraft and the ground.  The
receivers and transmitters for single access services are mounted in
compartments on the back of the single-access antennas.

     The antenna module is composed of seven antenna systems: two single-
access, the multiple access array, space-to-ground link and the S- band omni
for satellite health and housekeeping.  Commercial K-band and C- band antennas
round out the complement.

     For single-access service, the TDRSs have dual-feed S-band, Ku- band
parabolic (umbrella-like) antennas.  These antennas are free to be positioned
in two axis, directing the radio beam to orbiting user spacecraft below.
These antennas primarily relay communications to and from user spacecraft.
The high data rates provided by these antennas are available to users on a
time-shared basis.  Each antenna is capable of supporting two user spacecraft
services simultaneously -- one at S-band and one at Ku- band- provided both
users are within the beam width of the antenna.




     The multiple access antenna array is hard-mounted in one position on the
surface of the antenna module facing the Earth Another antenna, a 6.5- foot
(2-meter) parabolic reflector, provides the prime link for relaying
transmissions to and from the ground terminal at Ku-band.

Project Support

     TRW Space & Electronics Group, Redondo Beach, Calif., is the prime
spacecraft contractor.  Ground operations at the White Sands complex are
conducted by GTE Government Systems Corp., Needham Heights, Mass., and Bendix
Field Engineering Corp., Columbia, Md.


INERTIAL UPPER STAGE (IUS)

     The Inertial Upper Stage (IUS) will be used with the Space Shuttle to
transport NASA's sixth Tracking and Data Relay Satellite (TDRS-F) to
geosynchronous orbit, some 22,300 statute miles (35,880 km) from Earth.

Background

     The IUS was originally designed as a temporary stand-in for a reusable
space tug, and the IUS was named the Interim Upper Stage. The word "Inertial"
(signifying the guidance technique) later replaced "Interim" when it was
determined that the IUS would be needed through the 1990's.  In addition to
the TDRS missions, the IUS was utilized for the Magellan, Galileo and Ulysses
planetary missions.

     The IUS was developed and built under contract to the Air Force Systems
Command's Space Division. The Space Division is executive agent for all
Department of Defense activities pertaining to the Space Shuttle system and
provides the IUS to NASA for Space Shuttle use.  Boeing Aerospace Company,
Seattle, was selected in August 1976 to build the IUS.



Specifications


     IUS-13, to be used on mission STS-54, is a two-stage rocket.  Each stage
has a solid rocket motor, preferred over liquid-fueled engines for their
relative simplicity, high reliability, low cost and safety.

     The IUS is 17 feet (5.18 meters) long and 9.25 feet (2.8 m) in diameter.
It consists of an aft skirt; an aft stage solid rocket motor containing 21,400
pounds (9,707 kg) of propellant generating approximately 42,000 pounds
(188,496 newtons) of thrust; an interstage; a forward stage solid rocket motor
with 6,000 pounds (2,722 kg) of propellant generating approximately 18,000
pounds (80,784 newtons) of thrust and an equipment support section.

     The equipment support section 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.

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
TDRS-F in the orbiter payload bay and elevates the IUS/TDRS for final checkout
and deployment from the orbiter.

     The IUS ASE consists of the structure, aft tilt frame actuator,
batteries, electronics and cabling to support the IUS/TDRS combination.  These
ASE subsystems enable the deployment of the combined vehicle; provide,
distribute and/or control electrical power to the IUS and satellite and serve
as communication conduits between the IUS and/or satellite and the orbiter.

IUS Structure

     The IUS structure is capable of supporting the loads generated internally
and also by the cantilevered spacecraft during orbiter operations and the IUS
free flight.  In addition, the structure physically supports all the equipment
and solid rocket motors within the IUS, and provides the mechanisms for IUS
stage separation.  The major structural assemblies of the two-stage IUS are
the equipment support section, interstage and aft skirt.  It is made of
aluminum skin-stringer construction with longerons and ring frames.

Equipment Support Section

     The Equipment Support Section houses the majority of the IUS avionics.
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 TDRS.

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
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 with 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 attitude 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, power transfer unit, utility batteries, pyrotechnic
switching unit, IUS wiring harness and umbilical, and staging connectors.  The
IUS avionics system distributes electrical power to the IUS/TDRS interface
connector for all mission phases from prelaunch to spacecraft separation.

IUS Solid Rocket Motors

     The IUS uses a large and a small solid rocket motor employing 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 solid rocket motor 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 solid
propellant carried.

Reaction Control System

     The reaction control system controls the IUS/TDRS's attitude during
coasting; roll control during SRM thrustings and velocity impulses for
accurate orbit injection.

     As a minimum, the IUS includes one reaction control fuel tank with a
capacity of 120 pounds (54.4 kg) of hydrazine.  Production options are
available to add a second or third tank.  IUS-13 will carry two tanks, each
with 120 pounds (54.4 kg) of fuel.

     To avoid spacecraft contamination, the IUS has no forward facing
thrusters.  The reaction control system also provides the velocities for
spacing between several spacecraft deployments and for avoiding collision or
contamination after the spacecraft separates.

IUS-to-Spacecraft Interfaces

     The TDRS spacecraft 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 an insulation blanket of multiple layers of
double-aluminized Kapton and polyester net spacers across the IUS/TDRS
interface.  The outer layer of the blanket, facing the TDRS spacecraft, is a
special Teflon-coated fabric called Beta cloth.  The 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
normally are performed at this time.

     Forward payload restraints will be released and the aft frame of the
airborne support equipment will tilt the IUS/TDRS to 29 degrees.  This will
extend the TDRS into space just outside the orbiter payload bay, allowing
direct communication with Earth during systems checkout.  The orbiter will
then 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
IUS/TDRS predeployment operations have been successfully completed, a GO/NO-GO
decision for IUS/TDRS deployment will be sent to the crew.

     When the orbiter flight crew is given a GO decision, they will activate
the pyrotechnics that separates the IUS/TDRS umbilical cables.  The crew will
then 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 a pyrotechnic
separation device initiated to physically separate the IUS/spacecraft
combination from the tilt table.  Compressed springs provide the force to
jettison the IUS/TDRS from the orbiter payload bay at approximately 0.10
meters (4.2 inches) per second. The deployment is normally performed in the
shadow of the orbiter or in Earth eclipse.

     The tilt table will be lowered to minus 6 degrees after IUS and its
spacecraft are deployed.  Approximately 19 minutes after IUS/TDRS deployment,
the orbiter's engines will be ignited to move the orbiter away from the
IUS/TDRS.

     At this point, the IUS/TDRS is controlled by the IUS onboard computers.
Approximately 10 minutes after the IUS/TDRS is ejected from the orbiter, the
IUS onboard computer will send out signals used by the IUS and/or TDRS to
begin mission sequence events.  This signal also will enable the 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 ejection from the orbiter, the
pyrotechnic inhibits for the first solid rocket motor will be removed.  The
belly of the orbiter has been oriented towards the IUS/TDRS combination to
protect the 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.  This is expected at
approximately 60 minutes after deployment (L+7 hours, 13 minutes).  After
firing approximately 146 seconds and prior to reaching the apogee point of its
trajectory, the IUS first stage will expend its fuel.  While coasting, the IUS
will perform any maneuvers needed by TDRS for thermal protection or
communications.  When this is completed, the IUS first stage and interstage
will be separated from the IUS second stage.

     Approximately 6 hours, 12 minutes after deployment at approximately
L+12:30, the second stage motor will be ignited, thrusting for about 108
seconds.  After burn is complete, the IUS stabilizes the TDRS while the solar
arrays and two antennas are deployed.  The IUS second stage will separate and
perform a final collision/contamination avoidance maneuver before
deactivating.





DIFFUSE X-RAY SPECTROMETER (DXS)

     The Diffuse X-ray Spectrometer (DXS) addresses a fundamental question of
present-day astrophysics -- what is the origin and nature of the interstellar
medium, the matter that fills the space between stars?

     The DXS will study the hottest components of the interstellar medium,
gases at temperatures at approximately 1 million degrees Kelvin, by detecting
the x-rays emitted there.  By measuring the gas temperature and composition,
the DXS will provide important clues to the origin, evolution and physical
state of this constituent of the Milky Way galaxy.

     The hot interstellar medium is one phase in the life cycle of the
material in this galaxy.  By studying this life cycle, the DXS scientists hope
to learn more about the way the mass and energy of the galaxy are
redistributed as it evolves.  A better understanding of the evolution of the
galaxy is one of the steps toward understanding the nature and evolution of
galaxies, which contain most of the visible matter in the Universe.

     The DXS, developed by the University of Wisconsin, Madison, consists of
two identical instruments, one mounted to each side of the Shuttle cargo bay.
A DXS instrument consists of a detector, its associated gas supply and
electronics.  Each instrument is mounted to a 200-pound (91-kg) plate, which
is attached to the side of the Shuttle bay.

     These plates are part of the Goddard Space Flight Center's Shuttle
Payload of Opportunity Carrier (SPOC) standard hardware, which is part of the
Hitchhiker carrier system.

     The Hitchhiker system provides real-time communications between the
payload and customers in the Hitchhiker control center at Goddard Space Flight
Center, Greenbelt, Md. The carrier system is modular and expandable in
accordance with payload requirements.  Hitchhikers were created to provide a
quick reaction and low-cost capability for flying small payloads in the
Shuttle payload bay.

DXS Science

     A large percentage of x-rays from space do not originate from specific
objects like stars or galaxies, but from some source that appears to be
distributed over the entire sky.  Astronomers have found that these emissions
fall into two types: high-energy or "hard" x-rays that may be the unresolved
emissions from a collection of distant galaxies and low- energy or "soft"
x-rays that are not yet well understood.  DXS will study the latter.

       Because low energy x-rays cannot travel more than a few hundred light
years in interstellar space before they are absorbed, most of the diffuse soft
x-ray background observed must have originated in the Milky Way galaxy from
the vicinity of Earth's solar system.

       The DXS measures the arrival direction and wavelength of incident low
energy x-rays in the wavelength range of 42 to 84 angstroms -- an angstrom is
one ten-thousandth of a millimeter.  From this information, the DXS scientists

will be able to determine the spectrum (brightness at each wavelength) of the
diffuse soft x-ray background from each of several regions of the sky.

     By analyzing these spectral features, scientists can identify the
temperature, the ionization state and the elements which constitute this
plasma.  From these data they can tell whether the plasma is young and heated
in the last 100,000 years or old and heated millions of years ago.

     Previous experiments were not capable of measuring the spectrum of the
diffuse soft x-ray background.  With its spectral determination capability,
the DXS will make this type of measurement possible for the first time.

DXS Operations

     Once the Shuttle is on orbit and the payload bay doors are open, a crew
member will activate the experiment.  DXS will be operated from Goddard's
Payload Operations Control Center (POCC).  University of Wisconsin personnel
at Goddard will control and monitor the DXS, and Goddard personnel will
monitor and control the operations of the Hitchhiker carrier support hardware.

     The DXS instruments will collect x-ray data during approximately 64
orbital nights over 4 flight days.  In the orbit day periods throughout the
mission, the DXS will perform sensor calibrations and will periodically
replenish the detectors' gas supply.  Goddard's Flight Dynamics Facility and
the Spacelab Data Processing Facility will assist the DXS POCC operations and
data processing activities.

     After the Shuttle lands, the DXS instruments will be transported to the
University of Wisconsin for post-flight testing and calibration.

DXS History

     The DXS investigation was proposed and selected in response to a 1978
announcement of opportunity to conduct scientific investigations aboard the
Space Shuttle. NASA selected DXS and four other astrophysics investigations,
including three ultraviolet instruments and one x-ray telescope that flew in
December 1990 on the STS-35/Astro-1 mission.  All have scientific objectives
and requirements that can be accomplished in a 5- 10 day Shuttle mission.

     DXS was originally manifested to fly with the Broad Band X-ray Telescope
(BBXRT) on the second Shuttle High Energy Astrophysics Laboratory flight.  In
the re-manifesting that followed the Challenger accident, BBXRT flew on
Astro-1, and DXS moved to STS-54.





STS-54 EVA TEST OBJECTIVE

     On the fifth day of the STS-54 flight, Mission Specialists Greg Harbaugh
and Mario Runco, Jr., will perform the first in a series of test spacewalks to
be conducted on Shuttle missions during the years leading up to the
construction of Space Station Freedom, scheduled to begin in early 1996.

     Harbaugh will be designated Extravehicular Crew Member 1 (EV1) and Runco
will be EV2. Mission Specialist Susan Helms will assist with the spacewalk
from inside Endeavour's cabin as the intravehicular activity crew member (IV),
tracking the progress of Harbaugh and Runco as they move through various tasks
in the cargo bay.

     The spacewalk tests are designed to refine training methods for future
spacewalks, expand the experience of ground controllers, instructors and
astronauts and aid in better understanding the differences between true
weightlessness and the underwater facility used to train crew members.

      During the STS-54 spacewalk, Runco and Harbaugh will evaluate how well
they adapt to spacewalking, test their abilities to move about the cargo bay
with and without carrying items, test the ability to climb into a foot
restraint without handholds and test their ability to align a large object in
weightlessness.

     The spacewalk is the lowest priority test being performed on STS- 54.  No
extra cargo has been added to the flight for the test, and it will not have
any impact on the other payloads aboard Endeavour.

     To simulate carrying a large object, the astronauts will carry one
another: to evaluate how well large tools can be used, they will work with a
tool already aboard Endeavour designed to manually raise the tilt table for
the Tracking and Data Relay Satellite's Inertial Upper Stage booster; to
simulate how well they can align an object, they will attempt to place each
other into the brackets in Endeavour's airlock that hold the spacesuit
backpacks when not in use.

     Flight controllers expect many of these tasks to be awkward for the
spacewalkers, and finding out just how difficult they will be is one goal of
the tests.  Information from this spacewalk test will be combined with
information from many more that will follow to refine the understanding of
difficulties involved with spacewalk work.


MIDDECK EXPERIMENTS


DEVELOPMENTAL AND PHYSIOLOGICAL PROCESSES INFLUENCING SEED PRODUCTION IN
MICROGRAVITY (CHROMEX-4)

Principal Investigator Dr. Mary Musgrave, Louisiana State University

     CHROMEX-4 is designed to gain an understanding of the reproductive
abnormalities which apparently occur in plants exposed to microgravity, and to
determine whether changes in developmental processes may be due to spaceflight
conditions, especially microgravity.  This experiment also will help
understanding how gravity influences fertilization and development on Earth.

     To date, only a few studies have been conducted on developing seeds in
space, and they all showed very poor seed production.  NASA would like to use
plants as a source of food and atmospheric cleansing for astronauts staying in
space for extended periods of time.  Seed production is vital if crops like
wheat and rice are to be utilized for food.

     The effects of microgravity on the seed production of Arabidopsis
thaliana will be studied.  Arabidopsis thaliana is a small, cress-type plant
with white flowers.  Its small size, small genome and short life cycle (45
days) make it ideal for gene mapping studies.  It was chosen because it is
small enough to fit in the flight hardware, and its rapid life cycle and
numerous flowers will ensure that a maximum number of reproductive stages can
be observed in a limited number of plants.  Arabidopsis seeds will be planted
preflight so that 14-day-old plants, capable of producing seeds, can be flown.

     These plants will be flown inside the Plant Growth Unit (PGU), a closed
system that provides day/night lighting located in the orbiter middeck.  The
PGU will hold six Plant Growth Chambers (PGC's), each of which will contain
six plants.  The PGC's provide structural and nutritional support to the
plants while on orbit.

     The PGU replaces one standard middeck locker and requires 28 volts of
power from the orbiter.  This hardware provides lighting, limited temperature
control and data acquisition for post-flight analysis.  The PGU has previously
flown on STS-3, -51F, -29 and -41.

     Following the flight, the flowers and developing seeds will be preserved
and their structures will be subjected to gross morphological and histological
analysis to determine the locations and life cycle stages of reproductive
abnormality.  These structures will be examined in detail by
electron-microscopy.

     The remaining plant tissue also will be analyzed for soluble
carbohydrate, starch and chlorophyll.  Sections of roots and leaves would
examine other physiological processes that might be affected as a result of
exposure to microgravity.  All data will be compared with data gathered from
1g ground controls conducted at a later date using identical hardware.



     Dr.  Mary Musgrave of Louisiana State University is the Principal
Investigator. The experiment is sponsored by the Life Sciences Division of
NASA's Office of Space Science and Application. The experiment is managed by
the Kennedy Space Center.

COMMERCIAL GENERIC BIOPROCESSING APPARATUS (CGBA)

     The Commercial Generic Bioprocessing Apparatus (CGBA) payload is
sponsored by NASA's Office of Advanced Concepts and Technology and is
developed by BioServe Space Technologies, a NASA Center for the Commercial
Development of Space (CCDS) at the University of Colorado, Boulder. The
purpose of the CGBA is to allow a wide variety of sophisticated biomaterials,
life sciences and biotechnology investigations to be performed in one
apparatus in the microgravity environment.

Commercial Investigations

     During the STS-54 mission, the CGBA will support 28 separate commercial
investigations, loosely classified in three application areas: biomedical
testing and drug development, controlled ecological life support system
(CELSS) and agricultural development and manufacture of biological- based
materials.

     Biomedical Testing and Drug Development: To collect information on how
microgravity affects biological organisms, the CGBA will include 12 biomedical
test models.  Of the 12 test models, five are related to immune disorders.

     One will investigate the process in which certain cells engulf and
destroy foreign materials (phagocytosis); another will study bone marrow cell
cultures; two others will study the ability of the immune system to respond to
infectious-type materials (lymphocyte and T-cell induction) and one will
investigate the ability of immune cells to kill infectious cells (TNF-
Mediated Cytotoxicity).

     The other seven test models -- which are related to bone and
developmental disorders, wound healing, cancer and cellular disorders -- will
investigate bone tissue formation, brine shrimp development, pancreas and lung
development, tissue regeneration, inhibition of cell division processes,
stimulation of cell division processes and the ability of protein channels to
pass materials through cell membranes.

     Test model results will provide information to better understand diseases
and disorders that affect human health, including cancer, osteoporosis and
AIDS. In the future, these models may be used for the development and testing
of new drugs to treat these diseases.

     CELSS Development: To gain knowledge on how microgravity affects
micro-organisms, small animal systems, algae and higher plant life.  The CGBA
will include 10 ecological test systems.  Four test systems will examine
miniture wasp and fruit fly development, seed germination and seedling
processes for CELSS studies.

     Another four test systems will investigate bacterial products and
processes and bacterial colonies for waste management applications.  Two other
systems (Triiodid and Zirconium Peroxide) will study new materials to control
build-up of unwanted bacteria and other micro-organisms.

      Test system results will provide research information with many
commercial applications.  For example, evaluating higher plant growth in
microgravity could lead to new commercial opportunities in controlled
agriculture applications.  Test systems that alter micro-organisms or animal
cells to produce important pharmaceuticals later could be returned to Earth
for large-scale production.  Similarly, it may be possible to manipulate
agricultural materials to produce valuable seed stocks.

     Biomaterials Products and Processes: The CGBA also will be used to
investigate six different biomaterials products and processes.  Two
investigations will attempt to grow large protein and RNA crystals to yield
information for use in commercial drug development.  A third investigation
will evaluate the assembly of virus shells for use in a commercially-
developed drug delivery system.

     Another investigation will attempt to form a homogenous matrix of special
light-sensitive biological molecules called bacteriorhodopsin.  Such a matrix
may be used in novel electronic mass storage systems associated with
computers.  fifth experiment will use bacteria to form magnetosomes (tiny
magnets) for otential use in advanced electronics.  A sixth investigation will
use fibrin lot materials as a model of potentially implantable materials that
could be eveloped commercially as replacements for skin, tendons, blood
vessels and even cornea.

     Results from the 28 investigations will be considered in determining
subsequent steps toward commercialization.  STS-54 marks the second of six
CGBA flights.  Future flights will continue to focus on selecting and
developing investigations that show the greatest commercial potential.


Flight Hardware
  The CGBA consists of 192 Fluids Processing Apparatuses (FPAs) and 24 Group
Activation Packs (GAPs).  Each GAP will house eight FPAs. The FPAs will
contain biological sample materials which are mixed on-orbit to begin and
end an experiment.  Individual experiments will use two to 12 FPAs each.

     Half of the FPAs and GAPs will be stored in the orbiter middeck in two
Commercial Refrigerator Incubator Modules (CRIM).  The other half will be
stored in a standard stowage locker.  Each CRIM holds six GAPs and will be
operated at 37 degrees Celsius (98.6 degrees F. -- mammalian body temperature)
to support cell culture investigations.

     FPA: Sample materials are contained inside a glass barrel that has rubber
stoppers to separate three chambers.  For each investigation, the chambers
will contain precursor, initiation and termination fluids, respectively.  The
loaded glass barrel will be assembled into a plastic sheath that protects the
glass from breakage and serves as a second level of sample fluid containment.

     The FPAs are operated by a plunger mechanism that will be depressed
on-orbit, causing the chambers of precursor fluid and the stoppers to move
forward inside the glass barrel.  When a specific stopper reaches an
indentation in the glass barrel, initiation fluid from the second chamber is
injected into the first chamber, activating the biological process.



     Once processing is complete, the plunger will again be depressed until
the termination fluid in the third chamber is injected across the bypass in
the glass barrel into the first chamber.

     GAP: The GAP consists of a 4-inch diameter plastic cylinder and two
aluminum endcaps.  Eight FPAs will be contained around the inside
circumference of the GAP cylinder.  A crank extends into one end of the GAP
and attaches to a metal pressure plate.  By rotating the crank, the plate will
advance and depress the eight FPA plungers simultaneously.

On-orbit Operations

     Mission Specialists Susan Helms and Greg Harbaugh are the primary and
backup crew members, respectively, responsible for CGBA operations.  Upon
reaching orbit, they will initiate the various investigations by attaching a
crank handle to each GAP.

     Turning the crank will cause an internal plate to advance and push the
plungers on the contained FPAs. This action causes the fluids in the forward
chambers of each FPA to mix.  Most of the GAPs will be activated on either the
first or second flight day.

     The crew will terminate the investigations in a manner similar to
activation.  Attaching and turning the GAP crank will cause further depression
of the FPA plungers causing the fluid in the rear chamber to mix with the
processed biological materials.  This fluid typically will stop the process or
"fix" the sample for return to Earth in a preserved state.  Each of the 24
GAPs will be terminated at different time points during the mission.  In this
manner, sample materials can be processed from as little as 2 hours to nearly
the entire mission duration.

     For most of the investigations, simultaneous ground controls will be run.
Using identical hardware and sample fluids and materials, ground personnel
will activate and terminate FPAs in parallel with the flight crew.
Synchronization will be accomplished based on indications from the crew as to
when specific GAPs are operated.  A temperature controlled environment at
NASA's Kennedy Space Center will be used to duplicate flight conditions.

     After Endeavor has landed, the CRIMs and stowage locker will be turned
over to Bioserve personnel for deintegration.  Some sample processing will be
performed at Kennedy. Most FPAs will be shipped or hand- carried back to the
sponsoring labs for detailed analysis.

     Dr.  Marvin Luttges, Director of the Bioserve CCDS, is Program Manager
for CGBA. Drs. Louis Stodieck and Michael Robinson, also of Bioserve, are
responsible for mission management.


PHYSIOLOGICAL AND ANATOMICAL RODENT EXPERIMENT .02

Principal Investigator Kenneth M. Baldwin, Ph.D.
Department of Physiology and Biophysics
University of California, Irvine

Co-Investigator Vincent J. Caiozzo, Ph.D.
Department of Orthopaedic Surgery, College of Medicine
University of California, Irvine

     The second Physiological and Anatomical Rodent Experiment (PARE.02) is a
secondary payload flight experiment located in a Space Shuttle's mid- deck
locker.

     The goal of PARE.02 is to determine the extent to which short- term
exposure to microgravity alters the size, strength and endurance capacity
(stamina) of skeletal muscles normally used to help support the body against
the force of gravity.

     The study, managed by NASA's Ames Research Center, Mountain View, Calif.,
will use rodents because their muscles are known to respond rapidly to altered
gravity forces.

     When individuals are exposed to the microgravity of space, there appears
to be a significant loss in muscle mass.  This appears to be because the
muscle must no longer exert a sufficient level of force, which produces a
signal to the body to conserve mass.  However, the loss of muscle mass hinders
one's capability to function when returning to Earth. All movement patterns
are difficult, and the individual may be prone to accidents because of this
instability.  Scientists need to find the extent to which the muscle
atrophies, what impact the atrophy process has on muscle performance and how
to prevent the atrophy from occurring.

     Second, the problem of muscle atrophy is similar in part to what is seen
on Earth during the normal aging.  As one gets older, he/she becomes less
physically active and the degree of muscle disuse is exaggerated.  This leads
to the same problems as occur during exposure to microgravity.  Thus, if the
problem of atrophy in space can be solved, scientists should have a good
insight for maintaining the muscle system in a more viable condition as humans
age.

     Millions of dollars are spent annually to treat older individuals with
injuries and disabilities resulting from the general problem of muscle and
bone weakness, particularly in the female population.

     The information derived from such a project has obvious practical
relevance to the entire health care industry.  Any insight that can be
generated to prevent body dysfunction and injury, as well as to rehabilitate
the musculoskeletal system from the effects of disuse atrophy, are very
important to the broad range population base of our society.

     With the advent of the Space Shuttle program and Spacelab, it is now
possible to expose both humans and animals to the unique environment of
microgravity.  In this way scientists can begin to partition out the specific
effects of gravity in regulating the structural and functional properties of
the organ systems of the body.

     The Shuttle makes it possible for life to exist in a new environment that
is entirely foreign to the body, thereby enabling scientists to understand how
the force of gravity normally impacts health and well-being.

     This is the second phase of this research experiment.  The first studied
the effects of microgravity on how the muscle cells process the food humans
eat and transform the food into the energy necessary to enable the muscles to
function.  The experiment distinguished that the muscles isolated from animals
exposed to zero gravity had a reduced capacity to process fat substrate while
retaining a normal capacity to process carbohydrate for energy.

     This finding has important implications if it occurs in the intact
individual, because it would force a person to use his/her energy stores of
carbohydrate at a faster rate.  When this occurs the muscle loses its stamina
and the individual cannot sustain physical activity for as long a time.

     The PARE.02 project will examine the extent to which the muscle loses its
stamina after exposure to microgravity for 6 days.

     NASA's Ames Research Center provides payload and science management and
support for PARE.02. The project is sponsored by the Life Sciences Division of
NASA's Office of Space Science and Applications.




SOLID SURFACE COMBUSTION EXPERIMENT (SSCE)

Principal Investigator Professor Robert A. Altenkirch
Dean of Engineering, Mississippi State University

     The purpose of the SSCE is to study the physical and chemical mechanisms
of flame propagation over solid fuels in the absence of gravity- driven
buoyant or externally-imposed airflows.  The controlling mechanisms of flame
propagation in microgravity are different than in normal gravity.

     On Earth, gravity causes the air heated by the flame to rise.  This air
flow, called buoyant convention, feeds oxygen to the flame and cools the fire,
creating competing effects.  In microgravity, this flow is absent.  Therefore,
the fire is sustained only by the oxygen that it consumes as it migrates along
the fuel's surface.  The results of the SSCE have a practical application in
the evaluation of spacecraft fire hazards, as well as providing a better
understanding of flame propagation in microgravity and on Earth.

     The SSCE occupies four standard lockers in the orbiter middeck.  The
experiment consists of two parts -- the chamber module and the camera module.
The chamber module consists of a sealed combustion chamber which houses the
sample and is filled with a combination of oxygen and nitrogen.  The chamber
has two perpendicular viewports -- one on the side and one on the top.

     Two 16-mm color movie cameras mounted on the camera module record the
combustion process through the viewports.  In addition, thermocouples measure
temperature data while a pressure transducer measures changes in chamber
pressure.  These data are stored in the experiment computer for post-flight
analysis.

     Ashless filter paper was tested on the first five flights with different
mixtures of oxygen and nitrogen and with varying pressures.  The final three
tests will use polymethylmethacrylate (PMMA), commonly known as Plexiglas*.
Typically, one configuration will be tested per mission.  For this mission,
the chamber will contain a 35:65 ratio by volume of oxygen to nitrogen at a
total pressure of 1.0 atmosphere.

     A crew member provides power to the experiment and by activating a
switch, the crew member ignites the fuel and data collection begins.  After
approximately 75 seconds, the sample self-extinguishes and data collection
ceases.  The entire process takes approximately 25 minutes.

     This is the sixth in a series of eight experiments studying flame
propagation in space.  The experiment was flown aboard the STS-41, STS- 40,
STS-43, STS-50 and STS-47 Shuttle missions in October 1990, June 1991, August
1991, June 1992 and September 1992, respectively.

    SSCE was conceived by Professor Robert A. Altenkirch, Dean of Engineering
at Mississippi State University, and was built by the NASA Lewis Research
Center, Cleveland. The project is sponsored by the NASA Microgravity Science
and Applications Division of the Office of Space Science and Applications.



APPLICATION SPECIFIC PREPROGRAMMED EXPERIMENT CULTURE
SYSTEM PHYSICS OF TOYS (ASPEC)

Physics of Toys

        The STS-54 mission will carry a collection of children's toys for an
educational post-flight videotape on the Physics of Toys. A similar
opportunity took place on STS-51D in April 1985, and the subsequent videotape
of demonstrations conducted by the crew has become one of the most popular
educational resources NASA has offered to schools.

        Toys have long been used to help teach basic and advanced scientific
principles and concepts of force, motion and energy.  Many toys depend on
these principles and concepts to function.  Although teachers are able to
anticipate what toys may do in space, free from the gravity vector, unexpected
actions may be observed.  The possibility of discovery turns Physics of Toys
from just a collection of valuable science demonstrations into legitimate
science experiments.

        The tape to be created on STS-54 will feature new toys, toys that have
been flown before and toys that children can make themselves.  The tape will
be available to schools in the Fall of 1993.  The tape will use toys to teach
some basic principles of science and math to students using an investigative
approach.  Children will be encouraged to investigate the same toys in the
normal 1-gravity environment of Earth and then speculate on what those same
toys will do in the microgravity of space flight.

        In addition to the videotape, selected students in grades 3-5 from the
crewmembers' hometowns will actively participate as investigators and will
talk with the orbiting crew.  Through telephone and television links, these
students, while in their classrooms or other school facilities, will ask the
crew questions about the Physics of Toys experiments.  In preparation for this
opportunity, NASA traveled to each of the schools involved and conducted
pre-experiments with the toys.

        The Physics of Toys experiment is scheduled around noon EST on flight
day 3.  The experiment will begin with a brief videotape showing highlights of
the mission and a few of the coming events.  There will be a brief
introduction to the experiment and then the first crewmember will take
questions.  Only one school will be able to talk to a crewmember at a time.
Each school will have approximately 8 minutes.  The order of the crewmembers
and schools is as follows.



        o Sacred Heart School, Bronx, N.Y., will experiment with car and track
          and klacker balls. (Mario Runco)
        o Thomas A. Edison Elementary School, Willoughby, Ohio, will
          experiment with a basketball and magnetic marbles. (Greg Harbaugh)
        o Shaver Elementary School, Portland, Ore., will experiment with
          swimming toys and a flipping mouse. (Susan Helms) o Westwood
          Heights Schools, Flint, Mich., will experiment with gravitrons and
          a balloon helicopter. (Donald McMonagle)

        Any time remaining in the experiment after all schools have asked
their questions will be filled with selected demonstration of flying toys by
crew Commander John Casper.

STS-54 CREW BIOGRAPHIES

     John H. Casper, 48, Col., USAF, is Commander of Endeavour's third space
mission.  Selected to be an astronaut in 1984, Casper, from Gainesville, Ga.,
is making his second Shuttle flight.

     Casper served as Pilot on Atlantis' STS-36 mission in February 1990,
which carried Department of Defense payloads and a number of secondary
payloads.

     A graduate of Chamblee High School in Chamblee, Ga., in 1961, Casper
received a bachelor of science degree in engineering science from the U.S. Air
Force Academy in 1966 and a master of science degree in astronautics from
Purdue University in 1967.  He is a 1986 graduate of the Air Force Air War
College.

     Casper received his pilot wings at Reese Air Force Base, Texas, in 1968
and has logged more than 6,000 flying hours in 50 different aircraft.  His
first Shuttle mission lasted 106 hours.

     Donald (Don) R. McMonagle, 38, Col., USAF, is Pilot of STS-54. Born in
Flint, Mich., McMonagle was selected as a pilot astronaut in 1987 and made his
first flight as a mission specialist aboard Discovery on STS-39 in April 1991,
an unclassified Department of Defense mission.

     McMonagle graduated from Hamady High School in Flint in 1970.  He holds a
bachelor of science degree in astronautical engineering from the U.S. Air
Force Academy and a master of science in mechanical engineering from
California State University, Fresno.

     He graduated from pilot training at Columbus Air Force Base, Miss., in
1975 and has more than 4,200 hours of flying experience in a variety of
aircraft, primarily the T-38, F-4, F-15 and F-16. He logged more than 199
hours in space on his first Shuttle mission.

     Gregory (Greg) J. Harbaugh, 35, will serve as Mission Specialist 1.
Before being selected as an astronaut in 1978, Harbaugh held engineering and
technical management positions in various areas of Space Shuttle flight
operations -- particularly data processing systems -- and supported real-time
Shuttle operations from the JSC Mission Control Center for most of the flights
from STS-1 to STS-51L.

     Harbaugh, who considers Willoughby, Ohio, as his hometown, graduated from
Willoughby South High School in 1974, received a bachelor of science degree in
aeronautical and astronautical engineering from Purdue University in 1978 and
a master of science degree in physical science from the University of
Houston-Clear Lake in 1986.

     Harbaugh flew as a mission specialist on STS-39 and was responsible for
operation of the remote manipulator system robot arm and the Infrared
Background Signature Survey spacecraft.  With the completion of the mission,
he had logged 199 hours in space.


     Mario Runco Jr., 39, Lt. Cdr., USN, will serve as Mission Specialist 2.
From Yonkers, N.Y., Runco graduated from Cardinal Hayes High School in the
Bronx, N.Y., in 1970.

     He received a bachelor of science degree in meteorology and physical
oceanography from City College of New York in 1974 and a master of science
degree in meteorology from Rutgers University, New Brunswick, N.J., in 1976.

     After graduating from Rutgers, Runco worked for a year as a research
hydrologist conducting ground water surveys for the U.S. Geological Survey on
Long Island, N.Y. He worked as a New Jersey State Trooper until entering the
U.S. Navy in 1978 and being commissioned that same year.

     He served in various Navy posts, being designated a Naval Surface Warfare
Officer and conducting hydrographic and oceanography surveys of the Java Sea
and Indian Ocean before joining NASA.

     Runco served as a mission specialist aboard Atlantis on STS-44 in
November 1991, which deployed the Defense Support Program satellite and
conducted two Military Man in Space experiments, three radiation monitoring
experiments and numerous medical tests.  Runco logged more than 166 hours on
that flight.

     Susan J. Helms, 33, Capt., USAF, will serve as Mission Specialist 3 on
STS-54. From Portland, Ore., she was selected as an astronaut in 1990.

     Helms graduated from Parkrose Senior High School in Portland in 1976,
received a bachelor of science degree in aeronautical engineering from the
U.S. Air Force Academy in 1980 and a master of science degree in aeronautics
and astronautics from Stanford University in 1985.

     Helms was an F-16 weapons separation engineer at Eglin Air Force Base,
Fla., and served as an assistant professor of aeronautics at the academy.  In
1987, she attended Air Force Test Pilot School at Edwards Air Force Base,
Calif. and worked as a flight test engineer and project officer on the CF-18
aircraft at CFB Cold Lake, Alberta, Canada. As a flight test engineer, she has
flown in 30 different types of U.S. and Canadian military aircraft.  This will
be her first Space Shuttle flight.

MISSION MANAGEMENT FOR STS-54

NASA HEADQUARTERS, WASHINGTON, D.C.

Office of Space Flight

Jeremiah W. Pearson III - Associate Administrator
Brian O'Connor - Deputy Associate Administrator
Tom Utsman - Director, Space Shuttle
Leonard Nicholson - Manager, Space Shuttle
Brewster Shaw - Deputy Manager, Space Shuttle

Office of Space Science and Applications

Dr. Lennard Fisk - Associate Administrator
Al Diaz - Deputy Associate Administrator
Dr. George Newton - Acting Director, Astrophysics Division
Robert Benson - Director, Flight Systems Division
David Jarrett - DXS Program Manager
Dr. Louis Kaluzienski - DXS Program Scientist

Office of Advanced Concepts and Technology

Gregory M. Reck - Acting Associate Administrator
Ray J. Arnold, Director - Commercial Innovation & Competitiveness
Richard H. Ott, Director - Commercial Flight Experiments
Garland C. Misener - Chief, Flight Requirements & Accommodations

Office of Space Communications

Charles Force - Associate Administrator
Jerry Fitts - Deputy Associate Administrator
Eugene Ferrick - Director, Space Network
Jimie Maley - Manager, Launch and Space Segment
Daniel Brandel - Manager, TDRSS Continuation
Raymond Newman - Manager, Ground Segment
Wilson Lundy - Manager, White Sands Space Network Complex

Office of Safety and Mission Quality

Col. Frederick Gregory - Associate Administrator
Charles Mertz - (Acting) Deputy Associate Administrator
Richard Perry - Director, Programs Assurance

KENNEDY SPACE CENTER, FLA.

Robert L. Crippen - Director
James A. "Gene" Thomas - Deputy Director
Jay F. Honeycutt - Director, Shuttle Management and Operations
Robert B. Sieck - Launch Director
John J. "Tip" Talone - Endeavour Flow Director
J. Robert Lang - Director, Vehicle Engineering
Al J. Parrish - Director of Safety Reliability and Quality Assurance
John T. Conway - Director, Payload Management and Operations
P. Thomas Breakfield - Director, Shuttle Payload Operations
Joanne H. Morgan - Director, Payload Project Management
Roelof Schuiling - STS-54 Payload Processing Manager

MARSHALL SPACE FLIGHT CENTER, HUNTSVILLE, ALA.

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

JOHNSON SPACE CENTER, HOUSTON

Aaron Cohen - Director
Paul J. Weitz - Deputy Director
Daniel Germany - Manager, Orbiter and GFE Projects
David Leestma - Director, Flight Crew Operations
Eugene F. Kranz - Director, Mission Operations
Henry O. Pohl - Director, Engineering
Charles S. Harlan - Director, Safety, Reliability and Quality
Assurance

STENNIS SPACE CENTER, BAY ST LOUIS, MISS.

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

AMES-DRYDEN FLIGHT RESEARCH FACILITY, EDWARDS, CALIF.

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


AMES RESEARCH CENTER, MOUNTAIN VIEW, CALIF.

Dr. Dale L. Compton - Director
Victor L. Peterson - Deputy Director
Dr. Joseph C. Sharp - Director, Space Research

GODDARD SPACE FLIGHT CENTER, GREENBELT, MD.

Dr. John Klineberg - Center Director
Thomas E. Huber - Director, Engineering Directorate
Theodore C. Goldsmith - Project Manager, Shuttle Small Payloads
Steven C. Dunker - DXS Project Manager
Vernon J. Weyers -  Director, Flight Projects
Dale L. Fahnestock - Director, Mission Operations and Data Systems
Daniel A. Spintman - Chief, Networks Division
Vaughn E. Turner - Chief, Communications Division
Charles Vanek - Project Manager, TDRS
Thomas E. Williams - Deputy Project Manager, TDRS
Anthony B. Comberiate - TDRS Manager
Gary A. Morse - Network Director
16-Dec-92 Daily File Collection
   These files were added or updated between 15-Dec-92 at 21:00:00 {Central}
                                         and 16-Dec-92 at 21:00:13.

=--=--=START=--=--= NASA Spacelink File Name:921216.REL

12/16/92:  HUBBLE DISCOVERS PROTOPLANETARY DISKS AROUND NEW STARS

Paula Cleggett-Haleim
Headquarters, Washington, D.C.               December 16, 1992

Jim Elliott
Goddard Space Flight Center, Greenbelt, Md.

Ray Villard
Space Telescope Science Institute, Baltimore

RELEASE:  92-226


     NASA's Hubble Space Telescope has uncovered the strongest evidence yet
that many stars may form planetary systems.

     Dr.  C. Robert O'Dell of Rice University, Houston, and colleagues have
used Hubble to discover extended disks of dust around 15 newly-formed stars in
the Orion Nebula starbirth region 1,500 light-years away.

     Such disks are a prerequisite for the formation of solar systems like
Earth's, according to astronomers.

     "These images provide the best evidence for planetary systems," said
O'Dell. "The disks are a missing link in our understanding of how planets like
those in our solar system form.  Their discovery establishes that the basic
material of planets exists around a large fraction of stars.  It is likely
that many of these stars will have planetary systems."

     Hubble Space Telescope's detailed images confirm more than a century of
speculation, conjecture and theory about the genesis of a solar system.

     According to current theories, the dust contained within the disks
eventually agglomerates to make planets.  Earth's solar system is considered a
relic of just such a disk of dust that accompanied the sun's birth 4.5 billion
years ago.

     Before the Hubble discovery, protoplanetary disks had been confirmed
around only four stars, Beta Pictoris, Alpha Lyrae, Alpha Piscis Austrini and
Epsilon Eridani.

     Unlike these previous observations, Hubble has observed newly formed
stars less than a million years old which are still contracting out of
primordial gas.



     Hubble's images provide direct evidence that dust surrounding a newborn
star has too much spin to be drawn into the collapsing star.  Instead, the
material spreads out into a broad, flattened disk.

     These young disks signify an entirely new class of object uncovered in
the universe, according to O'Dell.

     Hubble can see the disks because they are illuminated by the hottest
stars n the Orion Nebula, and some of them are seen in silhouette against the
bright ebula.  However, some of these protoplanets are bright enough to have
been een previously as stars by ground-based optical and radio telescopes.
Their rue nature was not recognized until the Hubble discovery.

     Each protoplanet appears as a thick disk with a hole in the middle where
the cool star is located.  Radiation from nearby hot stars "boils off"
material rom the disk's surface at a rate equal to about one-half the mass of
Earth per ear.  This material is then blown back into a comet-like tail by a
stellar "wind" of radiation and subatomic particles streaming from nearby hot
stars.

     Based on this erosion rate, O'Dell estimates that a protoplanet's initial
mass would be at least 15 times that of the giant planet Jupiter.

     Many of the youngest and hottest stars in the Milky Way Galaxy are found
in the Orion Nebula. The nebula is on the near edge of a giant molecular cloud
which lies immediately behind the stars that trace the sword of the
constellation Orion the Hunter.

     The region of Orion is a bright part of the nebula where stars are being
uncovered at the highest rate.  These results suggest that nearly half the 50
stars in this part of Orion have protoplanetary disks.

     O'Dell's co-investigators are graduate students Zheng Wen and Xi-Hai Hu
of Rice University and Dr. Jeff Hester of Arizona State University. Their
results will be published in the Astrophysical Journal next spring under the
title "Discovery of New Objects in the Orion Nebula on HST Images: Shocks,
Compact Sources and Protoplanetary Disks."

     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
=--=--=-END-=--=--=
=--=--=START=--=--= NASA Spacelink File Name:921216.SHU

KSC SHUTTLE STATUS 12/16/92


              SPACE SHUTTLE STATUS REPORT
                   Kennedy Space Center, Florida

                   December 16, 1992


George H. Diller


Vehicle: OV-105/Endeavour   Mission Number: STS-54
Location: Launch Pad 39-B
Primary Payload: TDRS-F/IUS-13 + Diffuse X-ray Spectrometer (DXS)
Launch Timeframe: NET January 13   Mission Duration: 6 Days
Inclination: 28.45 degrees   Crew Size: 5
Nominal Landing Site: KSC


IN WORK TODAY:

- Flight Readiness Test of main engines and flight controls
- IUS Flight Readiness Checks
- calibration of inertial measurement units
- crew cabin and aft compartment cleaning
- SRB parachute camera installation
- avionics bay closeouts
- calibration of inertial measurement units


SCHEDULED:

- TACAN testing on Thursday
- KSC Launch Readiness Review on Thursday
- aft main engine compartment confidence test on Friday
- install IUS flight batteries on Friday
- Flight Readiness Review (FRR) on Dec. 22


WORK COMPLETED:

- Terminal Countdown Demonstration Test (TCDT)
- TDRS/IUS countdown simulation
- astronaut Pad B emergency egress training
- astronaut inspection of TDRS/IUS in payload bay
- delivery of liquid hydrogen to Pad B storage spheres
- orbiter/external tank cavity purge leak check
- preparation of orbiter hydraulics for Flight Readiness Test
- solid rocket booster flight battery installation



SPECIAL TOPICS:

Discovery Ferry Flight: Discovery atop the 747 Shuttle Carrier Aircraft landed
at Kelly Air Force Base in San Antonio, Texas last night at 8:14 p.m.  EST.
Departure is planned for tomorrow with a likely overnight stop in Mississippi
and arrival at KSC on Friday. Weather conditions are unacceptable in East
Texas
and Louisiana for continuing the ferry flight today.

STS-55 Solid Rocket Booster stacking activity: In the Vehicle Assembly
Building, the left forward center segment is being restacked today.  The right
forward center segment showed a slightly higher than acceptable leak rate
during high pressure testing yesterday.  Troubleshooting is in work and also
to
determine if there are any similarities to that of the left forward center
segment leak check problem.
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
=--=--=-END-=--=--=

=--=--=START=--=--= NASA Spacelink File Name:921216.SKD

DAILY NEWS/TV SKED 12/16/92

Daily News
Wednesday, December 16, 1992  Two Independence Square,
Washington, D.C.  Audio service: 202/358-3014

******************PLEASE NOTE THIS INFORMATION*******************

NASA Daily News will cease publication for the Christmas and New Year holidays
with this issue.  We will begin publication again on Monday, January 4, 1993.
Until then, Happy Holidays !  !  !


 % Terminal Countdown Test for STS-54 successfully concludes this morning;
 % Rice Astronomer to present Hubble images of proto-solar systems today;
 % New "role model" video solicits high school students for science and tech
   fields;
 % Seattle NASA Town Meeting gets underway at 4:00 am EST today, live on TV;
 % Innovative research program high altitude aircraft "rolls out" this Friday;
 % Galileo science team to present first look data from Earth-Moon flyby next
   week.

* * * * * * * * * * * * * * * *

The launch dress rehearsal for Endeavour's January STS-54 launch concluded
successfully this morning at the Kennedy Space Center. The five-member STS-54
flight crew will depart Kennedy for Houston later today.  KSC launch
management will hold their center-wide launch readiness review tomorrow.  Also
tomorrow, Endeavour's three main engines will have their hydraulic and control
systems tested as part of the final readiness processing for the launch.  The
Office of Space Flight formal flight readiness management review will occur
next Tuesday, Dec. 22.  Following the formal review, Space Flight management
will set a target launch date.

* * * * * * * * * * * * * * * *

Rice University astronomer C. Robert O'Dell and colleagues will discuss his
recent discovery of proto- solar systems in the Orion Nebula today at 1:00 pm
EST in the NASA Headquarters auditorium at 400 Maryland Ave., SW. O'Dell will
show Hubble Space Telescope images taken by the Wide Field/Planetary Camera of
extended disks of dust encircling stars in the Nebula-long known to be a
birthing ground for stars themselves.  Dust disks such as the ones discovered
by O'Dell have long been considered an elemental step in the formation of a
solar system.  In addition to still photographs, O'Dell will also show a video
which depicts what one would see when looking deeper and deeper into the Orion
Nebula, finally winding up with these dust-encircled, young stars.

* * * * * * * * * * * * * * * *

This afternoon at 2:00 pm EST, the Virginia Space Grant Consortium will
present the first program in a five-part series designed to highlight the
student careers of female and minority students.  The series is intended to
show middle and high school students that there are real and valid choices
they can make to pursue academic or career paths in the science and
engineering fields.  The first program today will focus on Apriel Hodarie, a
master's degree candidate in physics at Virginia's Hampton University. Hodarie
is researching ways in hich a laser can be used to detect deadly windshear.
The next program will be hown on February 10, also at 3:00 pm EST.

* * * * * * * * * * * * * * * *

The next NASA Town Meeting begins today at 4:00 pm EST, in Seattle,
Washington, t the Student Union Building on the campus of the University of
Washington. he four- hour-long program will be broadcast live on NASA Select
television. ASA Administrator Daniel Goldin and other senior NASA officials
are in Seattle today in preparation for their participation later this
afternoon.  NASA Select television will carry the Town Meeting live.

* * * * * * * * * * * * * * * *

Aurora Flight Sciences Corp. will unveil a key element in NASA's High Speed
Transport program this Friday, Dec. 18, at 11:00 am EST at the Manassas,
Virginia, airport.  The company will show off their Perseus remotely-piloted
extremely-high-altitude research aircraft.  The aircraft, which uses
technology first pioneered in the design and construction of the human-powered
Daedalus aircraft, uses lightweight composite materials and is powered by a
innovative 4-cycle, 4-cylinder engine which burns gasoline and oxygen diluted
through recirculated exhaust gases.  The aircraft will also use the Global
Positioning System as the navigation reference for its onboard guidance
system.  The craft can operate using pre- programmed flight sequences and also
can be remotely piloted.  NASA has ordered two Perseus aircraft from Aurora.
The company expects the vehicle to provide fundamental science data about the
environment at altitudes up to 25 kilometers (82,000 feet).  NASA wants to use
the vehicle to provide information about exhaust emissions from
next-generation supersonic airliners.

* * * * * * * * * * * * * * * *

Next Tuesday, Dec. 22, Galileo project managers and scientists will present
the first look results of the spacecraft's Dec. 8 near-encounter with the
Earth and its high-resolution reconnaissance of the Moon's polar regions in a
presentation from the Jet Propulsion Laboratory. The spacecraft trajectory
past the Earth enabled it to photograph the Earth and Moon in sequential,
receding, views which JPL expects to make into an Earth-Moon rotation
computer-reconstructed video.  The presentation will be shown live on NASA
Select TV.

   Here's the broadcast schedule for Public Affairs events on NASA Select TV.
Note that all events and times may change without notice, and that all times
listed are Eastern. Live indicates a program is transmittlive.

Wednesday, December 16, 1992

       12:15 pm  Aeronautics & Space Report.
       12:30 pm  STS-52 post-mission review with mission
                 pilot Michael Baker and mission specialist Charles Lacy
                 Veach.
Live    1:00 pm  Hubble Space Telescope briefing on proto-
                 planetary system discoveries with astronomer Bob O'Dell,
                 Rice University
Live    2:00 pm  Virginia S;ace Grant Consotrium role model
                 video for high school and middle school students.
Live    4:00 pm  NASA Town Meeting from Seattle, Washington.
     at 4:00 and 8:00 pm and 12:00 midnight the broadcast
                 schedule of the day repeats.

Friday, December 18, 1992

Live    2:00 pm  Total Quality Management Colloquium from NASA Headquarters.

Tuesday, December 22, 1992

Live    3:30 pm  Galileo-Earth 2/Moon flyby encounter post-
                 encounter science press briefing from Jet Propulsion
                 Laboratory.

NASA Select TV is carried on GE Satcom F2R, transponder 13, C-Band, 72 degrees
West Ltude, transponder frequency is 3960 MegaHertz, audio subcarrier is 6.8
MHz, polarization is vertical.
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
=--=--=-END-=--=--=

=--=--=START=--=--= NASA Spacelink File Name:921216A.REL

12/16/92:  HIGH-FLYING PERSEUS RESEARCH AIRCRAFT READY FOR ROLLOUT

Drucella Andersen
Headquarters, Washington, D.C.                    December 16, 1992

Alice Ann Toole
Aurora Flight Sciences Corp., Manassas, Va.



RELEASE:  92-227


        NASA Administrator Daniel S. Goldin will make the keynote speech when
a high-flying, unpiloted NASA atmospheric research aircraft called Perseus is
unveiled in Manassas, Va., on Dec. 18.

        When Perseus starts to fly science missions in 1994, it will gather
data to improve knowledge on the atmosphere at very high altitudes, including
the possible effect of exhaust emissions from next-generation supersonic
airliners.

        "Perseus is going to be a valuable new tool for many areas of
atmospheric research, especially understanding the processes that control
stratospheric ozone levels, so NASA and industry can produce future supersonic
transports that are both environmentally safe and economically competitive."

        Perseus, designed and built for NASA by Aurora Flight Sciences Corp.,
Manassas, Va., is the first aircraft designed specifically for atmospheric
science.  It will carry up to 110 pounds (50 kilograms) of instruments to a
maximum altitude of 82,000 feet (25 kilometers).

        Much of Perseus' technology derives from sport aviation and the
record-breaking Daedalus human-powered aircmodeled on the Daedalus design,
which had excellent aerodynamic performance.  The plane is made of lightweight
composite materials, much like sailplanes or gliders.

        Perseus' engine is based on the 4-cycle, 4-cylinder Rotax engine that
powers ultralight aircraft around the world, but is highly modified to burn a
mixture of gasoline and oxygen diluted by recirculated exhaust gas.  Aurora
developed the engine under a $500,000 NASA Small Business Innovation Research
grant.

        Perseus also is breaking new ground in other technologies like the
onboard computer which will guide many of its flights using preprogrammed
flight plans.  The autopilot will keep track of the plane's location via
signals from the Global Positioning System constellation of navigation
satellites.

        NASA has ordered two Perseus aircraft from Aurora Flight Sciences.
Successful research missions by the planes could lead to more general use of
advanced unpiloted aircraft for Earth science studies.

        "Perseus is not only going to do science to improve the environment,
but also is building an important new industry for the future," said Aurora
Flight Sciences President John Langford. "It is key to a new generation of in
situ measurement platforms that will lead to discoveries in areas such as
atmospheric science, global warming and the forecasting of severe storms."

     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
=--=--=-END-=--=--=

=--=--=START=--=--= NASA Spacelink File Name:6_7_2_16_6.TXT

12/16/92:  HUBBLE DISCOVERS PROTOPLANETARY DISKS AROUND NEW STARS

Paula Cleggett-Haleim
Headquarters, Washington, D.C.               December 16, 1992

Jim Elliott
Goddard Space Flight Center, Greenbelt, Md.

Ray Villard
Space Telescope Science Institute, Baltimore

RELEASE:  92-226


     NASA's Hubble Space Telescope has uncovered the strongest evidence yet
that many stars may form planetary systems.

     Dr.  C. Robert O'Dell of Rice University, Houston, and colleagues have
used Hubble to discover extended disks of dust around 15 newly-formed stars in
the Orion Nebula starbirth region 1,500 light-years away.

     Such disks are a prerequisite for the formation of solar systems like
Earth's, according to astronomers.

     "These images provide the best evidence for planetary systems," said
O'Dell. "The disks are a missing link in our understanding of how planets like
those in our solar system form.  Their discovery establishes that the basic
material of planets exists around a large fraction of stars.  It is likely
that many of these stars will have planetary systems."

     Hubble Space Telescope's detailed images confirm more than a century of
speculation, conjecture and theory about the genesis of a solar system.

     According to current theories, the dust contained within the disks
eventually agglomerates to make planets.  Earth's solar system is considered a
relic of just such a disk of dust that accompanied the sun's birth 4.5 billion
years ago.

     Before the Hubble discovery, protoplanetary disks had been confirmed
around only four stars, Beta Pictoris, Alpha Lyrae, Alpha Piscis Austrini and
Epsilon Eridani.

     Unlike these previous observations, Hubble has observed newly formed
stars less than a million years old which are still contracting out of
primordial gas.

     Hubble's images provide direct evidence that dust surrounding a newborn
star has too much spin to be drawn into the collapsing star.  Instead, the
material spreads out into a broad, flattened disk.

     These young disks signify an entirely new class of object uncovered in
the universe, according to O'Dell.

     Hubble can see the disks because they are illuminated by the hottest
stars in the Orion Nebula, and some of them are seen in silhouette against the
bright nebula.  However, some of these protoplanets are bright enough to have
been een previously as stars by ground-based optical and radio telescopes.
Their true nature was not recognized until the Hubble discovery.

     Each protoplanet appears as a thick disk with a hole in the middle where
the cool star is located.  Radiation from nearby hot stars "boils off"
material from the disk's surface at a rate equal to about one-half the mass of
Earth per year.  This material is then blown back into a comet-like tail by a
stellar "wind" of radiation and subatomic particles streaming from nearby hot
stars.

     Based on this erosion rate, O'Dell estimates that a protoplanet's initial
mass would be at least 15 times that of the giant planet Jupiter.

     Many of the youngest and hottest stars in the Milky Way Galaxy are found
in the Orion Nebula. The nebula is on the near edge of a giant molecular cloud
which lies immediately behind the stars that trace the sword of the
constellation Orion the Hunter.

     The region of Orion is a bright part of the nebula where stars are being
uncovered at the highest rate.  These results suggest that nearly half the 50
stars in this part of Orion have protoplanetary disks.

     O'Dell's co-investigators are graduate students Zheng Wen and Xi-Hai Hu
of Rice University and Dr. Jeff Hester of Arizona State University. Their
results will be published in the Astrophysical Journal next spring under the
title "Discovery of New Objects in the Orion Nebula on HST Images: Shocks,
Compact Sources and Protoplanetary Disks."

     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
=--=--=-END-=--=--=