From: yee@atlas.arc.nasa.gov (Peter Yee)
Subject: First 1993 shuttle mission demonstates unique capabilities [Release 93-4] (Forwarded)
Apparently-To: sci-space-news@ames.arc.nasa.gov
Followup-To: sci.space
Originator: yee@atlas.arc.nasa.gov
Reply-To: yee@atlas.arc.nasa.gov (Peter Yee)
Organization: NASA Ames Research Center, Moffett Field, CA
Date: Thu, 7 Jan 1993 01:14:29 GMT

Ed Campion
Headquarters, Washington, D.C.                              January 6, 1993
(Phone:  202/453-8536)


RELEASE:  93-004

FIRST 1993 SHUTTLE MISSION DEMONSTATES UNIQUE CAPABILITIES


	The versatility of NASA's Space Shuttle system will be demonstrated
next week during the first mission of 1993 when Shuttle Endeavour and her
crew conduct a diverse group of experiments and tasks in Earth orbit.

	During the mission, a communications satellite will be deployed, x-ray
astronomy observations will be taken, experiments covering a wide range of
scientific disiplines will be conducted and a spacewalk to evaluate training
techniques will be performed.

	Endeavour and her crew are scheduled to be launched on Wednesday,
Jan. 13 with a launch window opening at 8:52 a.m. EST.  The mission
duration is approximately 6 days with landing scheduled for Tuesday, Jan. 19
at Kennedy Space Center, Fla.

	Crew members for the STS-54 mission are Commander John Casper,
Pilot Don McMonagle and three mission specialists -- Mario Runco, Jr., Greg
Harbaugh and Susan Helms.  The STS-54 mission will be the third flight of
Space Shuttle Endeavour and the 53rd flight of the system overall.

Tracking and Data Relay Satellite System

	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 capabilities for mission success.

	Tracking and Data Relay Satellite (TDRS-6) being deployed on the STS-
54 mission is the sixth in a series of communications spacecraft planned for
the TDRS system.

	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.

Diffuse X-ray Spectrometer

	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?

	A large percentage of x-rays from space do not originate fobjects like
stars or galaxies, but from some source that appears to 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.

EVA Test Objectives

	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 1996.

	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 respectively 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.

CHROMEX-4

	Developmental and Physiological Processes Influencing Seed Production
in Microgravity (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 scientists understand how gravity influences
fertilization and development on Earth.

	To date, only a few studies have been conducted on developing seeds in
space.  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.

Commercial Generic Bioprocessing Apparatus

	The purpose of the Commercial Generic Bioprocessing Apparatus
(CGBA) is to allow a wide variety of sophisticated biomaterials, life sciences
and biotechnology investigations to be performed in one apparatus in
microgravity.

	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 and agricultural development and manufacture of biological-based
materials.

	Results from the 28 investigations will be carefully 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.

Physiological and Anatomical Rodent Experiment

	The second Physiological and Anatomical Rodent Experiment
(PARE.02) is a secondary payload flight experiment located in a locker on the
Space Shuttle's mid-deck.  The goal of PARE.02 is to determine the extent to
which short-term exposure to microgravity alters the size, strength and
stamina of skeletal muscles normally used to support the body against the
force of gravity.

	The PARE.02 experiment is important for two reasons.  When
individuals are exposed to ta 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 out 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 span of aging.  As one gets older, he or 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 good insight for maintaining the muscle system in a
more viable condition as people age.

Solid Surface Combustion Experiment

	The purpose of the Solid Surface Combustion Experiment (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 convection, 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.
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