Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/STATION/STFMAR90.NWS

Text File | 1992-09-09 | 28KB | 545 lines

STATION BREAK:  VOL. 2, NO. 3, MARCH 1990
LDEF: A Treasure Trove  for  Space  Station

After six years in space, a 57-experiment satellite cradling a treasure
trove of information for Space Station Freedom was captured last month by
Columbia astronauts.

The Long Duration Exposure Facility (LDEF), designed and built by the NASA
Langley Research Center, has been home for the experiments of over 200
principle investigators from around the world during its extended space
saga.  These experiments will be returning to their Earth laboratories
this spring for extensive analyses.

Not only will the Long Duration Exposure Facility spout invaluable data
about the space environment and its effects from its tapestry of
experiments designed for that purpose, but the satellite's six-year
battering in space offers an unprecedented opportunity to examine the
spacecraft as a system.

There is nothing one dimensional about the LDEF or our approach to its
analysis," said Sally Little, a primary LDEF investigator now working at
the Space Station Freedom Program Office in Reston, Va.  The LDEF
experimenters will have a wealth of information for the aerospace world
community."

In addition, the Langley Research Center has established special
investigative groups (called "SIGS"), composed of experts in selected
disciplines, to analyze the whole spacecraft as a space environmental
effects experiment and to integrate the LDEF data into a usable database.
This effort is being managed by Dr. Bill Kinard, LDEF's Chief Scientist
and Director of Langley's LDEF Data Analysis Project Office.

LDEF experimenters and special investigators are working closely together
to make the LDEF as valuable as possible," said Little.  She serves in
both capacities in her special assignment representing Space Station
Freedom and also as an experimenter from the Solar Array Materials Passive
LDEF Experiment (called "SAMPLE").  She shares the latter responsibility
with investigators from the Marshall Space Flight Center, Lewis Research
Center, Goddard Space Flight Center, and Jet Propulsion Laboratory.

"Freedom has been targeted by Langley as one of the principle
beneficiaries for LDEF-derived information.   We have excellent
representation on the SIGS, which are charted to perform special
investigations and disseminate LDEF results.  It is through this process
that Freedom interests will be expressed and satisfied.

"This is an exciting opportunity for Space Station Freedom.  This
long-duration, synergistic data has never existed before.  It provides a
beautiful reality check for our modeling and ground-based testing efforts.

"We would expect that the impact to Space Station Freedom would primarily
be in the form of enhancements.  Our initial observations of LDEF do not
indicate any radical departures from our qualitative understanding of
space environmental effects, although we certainly see things that we
can't explain yet.  And we haven't quantified anything yet.  Our analysis
is clearly in its infancy, but we hope to 'grow-up' fast to meet the needs
of spacecraft designers.

"The intensity of curiosity is so high among investigators that it will
surely continue to drive us to an accelerated pace.  It really brings it
home how desperate scientists and technologists have all been for
opportunities like this."

For almost six years, LDEF was exposed to a complex combination of
different components that make up the ever-changing space environment.
These include atomic oxygen, solar radiation, particle radiation,
micrometeoroids and man-made debris.  These vary with solar activity,
orbital altitude, and season.#While certain space effects on materials and
systems are known, the complexity of the space environment and the
difficulty in performing simulations on Earth have limited knowledge on
how spacecraft materials and systems will react to the various components
of the environment and its combined effects.  Long-duration data is
particularly scarce.

"LDEF promises to provide important pieces to this puzzle.  And not just
about how specific materials survive.  Bill Kinard has a favorite saying
that 'the LDEF is not just a materials experiment.'  Now it would be
invaluable if it was just that, but it is certainly much more," said
Little.

"The potential is apparent in the initial observations made by our
experimenters, and our special teams focused on micrometeoroids and
debris, radiation, systems, and materials investigations.  It's just the
tip of the iceberg, because we've only been able to touch the visual realm
so far.  One thing for certain--seeing is believing.  The LDEF provides
testimony to the harshness of the space environment.  It clearly com-
mands our attention and challenges us to better understand effects and
mechanisms as we continue to expand our presence in space."

Kinard estimates that it will take at least two years of vigorous activity
to extract much of the treasures of LDEF.  LDEF experimenters and the
special investigative groups will have their first data analysis workshop
at Langley in late summer.  A major symposium is scheduled for the spring
of 1990.

In the meantime, the LDEF Systems SIGS will publish an in-house monthly
newsletter to keep participants informed about data analyses plans and
progress.  Space Station Freedom representatives on the special
investigative teams will be communicating relevant information to the
space station community on an on-going basis.

"LDEF embodies the NASA theme of 'The Journey Continues' for its mission
is far from over," said Little.  "It's our hope that the best is yet to
come -- with LDEF as our teacher."



Little Gets an Early look at 'SAMPLE'

As the STS-32 astronauts made their final approach toward LDEF, they saw
something small glistening in the sunlight near the LDEF.  They thought it
looked like solar cells.  Sally Little used their superb on-orbit
photography to confirm that it was indeed a solar cell module from the
Solar Array Materials Passive LDEF Experiment (SAMPLE).

"The odds of seeing it floating near the LDEF at the time of retrieval
were so remote," said Little.  "We are incredibly lucky.  We could also
see from the photographs that another module from the  experiment was
barely hanging on when the LDEF was grappled.  We didn't think we would
ever see that one again either, but we found it in the payload bay --
still intact."

SAMPLE experimenters do not find it difficult to offer a preliminary
explanation for why the modules fell off the LDEF.  They were attached to
2 miles of Kapton H (a polyimide film commonly used as a substrate for
solar arrays) which was not expected to survive the intense impingement of
atomic oxygen for almost six years.  "The Kapton was completely eroded
away leaving only the solar cells and its interconnect system," said
Little.  "It was not designed for the exposure it received when the
retrieval of LDEF was delayed.  We needed at least an additional 8 miles
to survive this trip."

In most respects, the value of SAMPLE has been enhanced by its extended
stay in space.  "For example, our Kapton samples that have protective
coatings are still there,"said Little.  This is of immediate interest to
the Hubble Space Telescope, expected to be launched in April, because its
solar arrays are protected with a similar silicone coating on the Kapton
H.

"We designed SAMPLE with the needs of spacecraft designers in mind.  With
over 300 material specimens on SAMPLE, we think we will generate a lot of
useful information with direct applications for Space Station Freedom.  We
certainly hope to contribute to a better understanding of the fundamentals
of mechanisms and effects as well."


NASA Seeks $2.45 Billion for Space Station Freedom's 1991 Budget

NASA's Space Station Freedom program is seeking $2.45 billion for fiscal
year 1991, $701 million more than this year's operating budget of $1.749
billion.

"Space Station Freedom is the cornerstone of our space program in the
1990s and beyond, including the Human Exploration Initiative," NASA
Administrator Richard H. Truly said.   "Fiscal year 1991 will be the year
that Space Station Freedom makes the critical transition from design to
actual fabrication of major long-lead-time hardware.  We are fully
committed to keeping this program, which involves significant
international participation, moving forward and on track."

NASA is seeking a 22 percent increase to $15.1 billion for its overall
fiscal year 1991 budget, $2.8 billion more than the $12.8 billion Congress
allotted the agency this year.  The President had requested a budget of
$13.4 billion for 1990.  The agency's fiscal year 1991 budget request
would support two new initiatives -- the Earth Observing System, as part
of the U.S. Global Change Research Program; and development of new
technology to boost human exploration beyond Earth's orbit.

Truly told a Congressional panel in February that the fiscal year 1991
budget request for space station was absolutely essential to keep Freedom
on schedule.  To provide greater program stability, NASA is also
requesting a three-year advance authorization and appropriation of $2.91
billion in fiscal year 1992 and 43.01 billion in fiscal year 1993.

"Funding instability has been
a real problem for the space station program," said Richard Kohrs,
director of NASA's space station program.  "We badly need to solve this
problem if we are going to complete the baseline station before the start
of the 21st century."

Frequent budget shortfalls in previous years have led to disruptive
program schedule and content adjustments.  These disruptions have reduced
program cost-effectiveness by diverting resources away from the space
station development effort for replanning activities.

Kohrs said the requested three-year appropriation would protect the space
station program's current assembly schedule.  First element launch is
planned for early 1995, man-tended capability is planned for early 1996,
permanently manned capability is planned for mid-1997, and assembly
complete is planned for mid-1999.

NASA's request for overall research and development for Freedom accounts
for $2.29 billion of the fiscal year 1991 request.  The Flight Telerobotic
Servicer will cost $106 million in 1991; advanced programs, $36 million;
and operations, $8.9 million.

The money will be distributed among the four work package centers and
other NASA installations.

Johnson Space Center in Houston would receive $1.051 billion; Marshall
Space Flight Center in Huntsville, Ala., $531 million; Lewis Research
Center in Cleveland, Ohio, $369 million; Goddard Space Flight Center in
Greenbelt, Md., $140 million; and Headquarters in Washington, D.C., and
Reston, Va., $257 million.

The baseline is comprised of a 500-foot-long single horizontal boom
structure with eight solar arrays that generate 75kW of photovoltaic
power, the U.S. laboratory and living quarters, four resource nodes, two
international laboratory modules (European and Japanese), and a Canadian
mobile servicing center.

Marshall, working with Boeing and various supporting contractors, is
responsible for pressurized modules, associated systems, logistics
elements, and payload operations.

Johnson whose prime contractor is McDonnell Douglas, is responsible for
the central truss structure, the resource nodes, various flight systems,
crew training, and flight operations.

Goddard, working with General Electric, is responsible for the attached
payloads accommodation equipment and the Polar Platform, soon to be
transferred to the Office of Space Science and Applications.

Lewis Research Center, whose prime contractor is Rocketdyne, is
responsible for Freedom's power.

In addition to the manned base, the station program includes the
development of a flight telerobotic servicer.  The telerobotic servicer is
a robot that can show its operator what it sees via a camera. By seeing
what the robot sees, the operator can make precise maneuvers to build,
attach, or repair equipment in space.  This robot will reduce the number
of times astronauts must leave the safe-haven of the station to work in
the unforgiving atmosphere of space.


Electronic Waiter May Handle Menu for Space Station Freedom Crew#

If a system developed by a Johnson Space Center (JSC) cooperative
education student is chosen, Space Station Freedom may have an electronic
waiter to keep track of its 14,000-item pantry and make choosing meals as
easy as saying, "Please."

The Voice Actuated Inventory System (VAIS) is a project developed by David
Rodriguez, an electrical engineering student from Purdue who worked in the
Telemetry and Audio Section of the Tracking and Communications Division.
Although Rodriguez' brainchild is only one of many being considered, it is
a good example of how space station research is pushing technology.

With the system, crew members would actually converse with acomputer that
tracks the station's inventory of food, selecting meals and snacks and
checking their supplies.  Commands to the computer are given with one of
27 single words, while the computer answers the user, saying, "Please
choose a meal," or asking, "Would you like to choose a meal or check
inventory?"  The computers voice is a recording of Rodriguez.

Many inventory systems are being studied for Freedom, including bar coding
of food or a touch screen computer system.  But a voice-actuated system
may be the simplest to operate,  Rodriguez said.

"It provides for hands-free operations," he explained.  "And the
microgravity action and reaction forces to come into play."

The system now in the space station mockup at JSC is only a model of what
VAIS may become once its vocabulary is expanded and the system is refined.
"But I hope it will be a working model for any type of inventory system
that goes up," he said.  "The best thing about this project is that there
are so many people excited about it, people working on foods, inventory,
voice control, and in the mockup."

Putting VAIS together was a difficult chore, but the long hours were worth
it, he said.  "The whole time, I was enjoying what I was doing, and that
makes it fly by a lot faster," he said.  "It's a leading edge of
technology.  I learned a lot about voice recognition, and that's useful."

VAIS may be one of the most user-friendly voice recognition system yet
developed at JSC, since Rodriguez used two male voices and two female
voices to program the computer's recognition of commands, said Bill
Jordan, technical assistant to the chief of the Tracking and
Communications Division.

"He did an outstanding job with it.  The technology of voice recognition
is still more of an art than a science, but he built up the software with
an effort to solve some of the problems," Jordan said.  "The real test is
gong to be leaving it in the mockup for a while and seeing what people
think of it."


Unisys Houston on New Quality/Safety Team

After winning a $150 million NASA contract, Unisys Houston Operations is a
part of the team that will provide safety, reliability and quality
assurance for the Space Station Freedom program .

Support will be provided at Johnson Space Center (JSC).

A contract awarded by NASA gives the team responsibility for the safety,
reliability, maintainability and quality assurance of the space station
software systems, computer hardware and physical components.

In addition to Unisys, the team encompasses prime contractor Ford
Aerospace, CalSpan, Ebasco and Technical Analysis Inc.

The $150 million two-year contract includes three one-year renewal
options.

"We are honored to have the opportunity to make another major contribution
to safe, successful spaceflight," said John B. Munson, vice president and
general manager of Unisys' Air Defense and Space Systems Division that
includes Unisys Houston.

The company is part of the missions systems contract team JSC recently
selected to provide hardware, software and systems integration for space
station's control center.

Unisys' safety and reliability responsibilities will include the quality
assurance and verification of ground-based software.


The Lightning Imaging Sensor to Measure Activity#

This article is the second in a series on Office of Space Science and
Applications attached payloads, selected by Announcement of Opportunity in
June 1989.

The Lightning Imaging Sensor (LIS) is a conceptually simple device that
discovers, locates, and measures lightning.  A staring imager detects both
intracloud and cloud-to-ground lightning over a large region of the
Earth's surface, marks the time of occurrence, and measures the radiant
energy.

This calibrated optical imaging sensor will collect data on the global
distribution of total lightning and provide information that will help us
better understand the interrelated processes of lightning and the
atmosphere, such as the global  electric circuit, precipitation
relationships with lightning, trace gas interactions, magnetospheric/
ionospheric coupling, and atmospheric circulation and convection.
Currently, LIS is proposed to be included in the Earth Observation System
(EOS) program.

Lightning measurements from Space Station Freedom by LIS will contribute
significantly to several important EOS mission objectives.  For example,
lightning is closely coupled to storm convection, dynamics, and
microphysics, and can be correlated to the global rates, amount, and
distribution of precipitation, as well as to the release and transport of
latent heat.  LIS's goal is to detect and locate total lightning activity
with a 90% detection efficiency under both daytime and nighttime
conditions with high resolution, and measure the radiant energy of the
lightning occurrence.

The ground-track speed of  Freedom will allow LIS to monitor lightning
events occurring within an individual storm, and observation can then be
correlated with that storm system, as detected and measured by other
ground-based systems.

LIS is a small, light-weight, low power sensor (typically 15w).  Its
imaging system is a simple telescope consisting of a beam-expander, an
interference filter, and imaging optics.

LIS is designed to take advantage of the significant difference in
temporal, spatial, and spectral characteristics between the lightning
flashes and the ambient background.  To enhance its lightning detection
capability, LIS's real-time processor generates an estimate of the
background scene to effectively reduce the background illumination.

LIS will view a total area of over 400,000 square kilometers at any given
time.  Events are digitized, time-tagged, and transmitted via interface
electronics.

The Principle Investigator for LIS is Dr. Hugh Christian, NASA's Marshall
Space Flight Center, Huntsville, Alabama.  Dr. Christian is supported by a
team of three scientists.


Gravitational Biology Research on Freedom to Help Solve Mysteries on Earth

The constant presence of gravity is a major feature of Earth's environment
that most of us probably take for granted.  But, since all life on Earth
evolved in the presence of gravity, it plays a role in virtually all life
processes.

Gravity influences the morphology, physiology, and behavior of life in
virtually all of its manifestations.  This role is not yet well
understood, since biologists have not been able to study biological
processes in the absence of gravity until very recently.  Access to space
now provides us an opportunity to manipulate gravity from 1-g (Earth's
gravity) to almost zero, providing a broad-based gravitational research
capability.

Research that examines the degree to which living organisms perceive and
respond to gravity and adapt to low gravity is making, and will continue
to make, a significant contribution to our basic understanding of life.

The goals of NASA's Space/ Gravitational Biology Program are to use low
gravity and other unique characteristics of the space environment to
advance knowledge in the biological sciences, to understand the role of
gravity in the biological processes of plants and animals, to determine
the effects of the interaction of gravity and other environmental stresses
on biological systems, and to understand how plants and animals are
affected by, and adapt to, the space environment.

Research sponsored by the Space/ Gravitational Biology Program is intended
to study and define the role of gravity in life on Earth by addressing
questions such as: How do plant cells detect gravity and translate the
force into neural, hormonal, or other physiological signals?  Can plants
and animals reproduce over several generations in low gravity?  What is
the relative contribution of gravity to sensorimotor functions?  What
fundamental biochemical and physical processes govern bone formation and
resorption?

Using the Centrifuge Facility (see January 1990 Station Break) to provide
simulated Earth gravity levels and fractional gravity levels--such as
lunar one-sixth g and martian one-third g--scientists may establish
thresholds for gravity sensing.  One-g control experiments will permit
scientists to determine which biological effects are gravity-dependent and
which depend on other factors.

Investigations on Space Station Freedom will attempt to identify
gravity-sensing organs and mechanisms in plants and animals and define how
they work in 1-g and adapt to low gravity.  Experiments also will aim to
determine how gravitational cues are registered, processed, transmitted,
and integrated into biological responses.

Development biology investigations will be conducted in space to determine
whether plants and animals, and multiple generations of plants and
animals, can develop normally in low gravity.

Investigations also will attempt to identify plant and animal
developmental stages, systems, and mechanisms that are sensitive to
gravity.  Investigations of biological adaptation to gravity will attempt
to define the role of gravity in regulating metabolism, fluid dynamics,
and biorhythms.  Investigations of this kind are developed to also
understand the basic mechanisms of mineral and hormonal homeostasis
(equilibrium) and the role of calcium in mediating the effects of gravity.

Cell biology investigations in space will attempt to determine how and
where gravity affects cells and to assess the permanence of microgravity
effects on cells.  The Gravitational Biology Facility being developed for
Space Station Freedom will include equipment to support
space/gravitational biology investigations using plant, animal, and human
subjects, including plant and animal experiments on the Centrifuge
Facility.

In addition to experiment-specific hardware, the double-rack facility will
include an animal biotelemetry system for monitoring animal subjects, a
perfusion and fixation unit for treating and preserving animal tissue
samples, and a tissue-equivalent proportional counter for measuring
radiation doses at the organ/cellular level.

It also will carry a mass spectrometer for analyzing solutions or gases,
an ion chromatograph for monitoring plant specimens, and an experiment
control computer system for storing experimental data and interfacing
between experiment -specific hardware and Freedom's data management
system.

The Gravitational Biology Facility is being developed as part of the Space
Biology Initiative (SBI), a space life sciences program that will yield
facilities for exobiology, gravitational biology, space physiology, and
controlled ecological life support systems (CELSS) research on Space
Station Freedom.  Because of the biological variability and the inherent
complexity of living systems, life sciences research requires a series of
investigations that each build on the results of preceding ones, each
probing more deeply to find fundamental answers.

The SBI will enable this kind of serial research, allowing scientists to
mount in-depth, highly sensitive and ultimately comprehensive
investigations of how biological systems respond to the absence of
gravity, honing in on specific biological and physiological processes that
are affected by exposure to space.


Accuracy Testing for Space Station Power


This solar concentrator for a solar dynamic space power system underwent
acceptance testing recently at the Lewis Research Center in Cleveland,
Ohio.

Solar dynamic power systems utilize the sun's energy as heat instead of
light -- as do solar cells -- for the production of power.

Energy that is collected at the focal point of a concentrating mirror
heats a fluid, which in turn rotates a turbine-driven alternator, thus
generating power similar to the way power is generated on Earth.  The
solar dynamic system is being developed for the growth phase of Space
Station Freedom.

In order to determine the accuracy of the concentrator, tests were
conducted using a laser beam directed at a point on each of the mirror
facets.  A camera mounted on a truss records the reflected image.  This
image is transferred to a television monitor, where it is observed to
detect possible alignment errors and also to check the surface
characteristics of the mirror.

These tests were conducted in Lewis' Power Systems Facility by the Harris
Corporation, the manufacturer of the concentrator.


NEWS BRIEFS

* Kennedy Space Center Director Forrest McCartney announced that John R.
"Dick" Lyon will become manager of the Space Station Projects Office,
replacing C.M. Giesler, who recently retired.

Lyon's most recent position at KSC was deputy director of Payload
Management and Operations.  He has an extensive background in both payload
operations and design engineering.

Lyon's experience spans numerous NASA accomplishments from the Apollo
program onward.  He joined NASA at KSC in June 1964.  He was responsible
for developing the KSC ground systems design criteria and activation
planning for the Apollo spacecraft and lunar module at launch complexes
34, 37, and 39, among other activities.

* NASA managers last month said their participation in the Japanese
Utilization Symposium in Tokyo went well.  Managers discussed user
integration, crew selection, and a pricing policy.

* Last month Richard Kohrs, director of the Space Station Freedom program,
testified before the House Space Science and Applications Subcommittee.
The next congressional hearing should be at the end of this month.

* Johnson Space Center (JSC)  in Houston recently completed its data
management system preliminary design review.  Also complete was a crew
review of the station at Work Package 1 at Marshall Space Flight Center in
Huntsville, Ala., and JSC.

* In 1991 and 1992, respectively, NASA will have two Flight Telerobotic
Servicer (FTS) demonstrationtest flights aboard the space shuttle.  The
test flights will be managed by Goddard Space Flight Center in Greenbelt,
Md., and Martin Marietta Corp. in Denver, Colo.  The FTS will be used to
help assemble and maintain Space Station Freedom  and its numerous
payloads.

* The Space Station Advisory Committee  (SSAC) met last month to discuss
the space station rephasing, and the committee's role in the reorganized
Office of Space Flight.

Dr. William Lenoir, associate administrator for the Office of Space
Flight, said he foresees an increased role for the SSAC.

Lenoir said the space station program could use input from the committee
in areas such as automation, robotics, space suits, the Flight Telerobotic
Servicer, and orbital debris. The committee's next meeting is in May.