yee@ames.arc.nasa.gov (Peter E. Yee) (09/08/88)
-15-
TRACKING AND DATA RELAY SATELLITE SYSTEM
The Tracking and Data Relay Satellite (TDRS-C) is the third
TDRS advanced communications spacecraft to be launched aboard the
Space Shuttle. TDRS-1 was launched during Challenger's maiden
flight in April 1983. The second, TDRS-B, was lost during the
Challenger accident of January 1986.
TDRS-1 is now in geosynchronous orbit over the Atlantic
Ocean just east of Brazil (41 degrees west longitude). It
initially failed to reach its desired orbit, following successful
Shuttle deployment, because of booster rocket failure. A NASA-
industry team conducted a series of delicate spacecraft maneuvers
over a 2-month period to place TDRS-1 into the desired 22,300
mile altitude.
Following arrival at geosynchronous altitude, TDRS-C (TDRS-3
in orbit) will undergo a series of tests prior to being moved to
its operational geosynchronous position over the Pacific Ocean
south of Hawaii (171 degrees W. longitude).
TDRS-3 and its identical sister satellite will support up to
23 user spacecraft simultaneously, providing two basic types of
service -- a multiple access service which can simultaneously
relay data from as many as 19 low-data-rate user spacecraft, and
a single access service which will provide two high-data-rate
communication relays from each satellite.
TDRS-3 will be deployed from the orbiter approximately 6
hours after launch. Transfer to geosynchronous orbit will be
provided by the solid propellant Boeing/U.S. Air Force Inertial
Upper Stage (IUS). Separation from the IUS occurs approximately
13 hours after launch.
The next TDRS spacecraft, currently targeted for launch in
January 1989, will replace the partially-degraded TDRS-1 over the
Atlantic. TDRS-1 will be moved to a location between the two
operational TDRS spacecraft and serve as an on-orbit spare.
The concept of using advanced communications satellites was
developed following studies in the early 1970s which showed that
a system of communication satellites operated, from a single
ground terminal, could support Space Shuttle and other low Earth-
orbit space missions more effectively than a worldwide network of
ground stations.
NASA's Space Tracking and Data Network ground stations will
be significantly reduced in number. Three of the network's
present ground stations -- Madrid, Spain; Canberra, Australia;
and Goldstone, Calif. -- already have been transferred to the
Deep Space Network managed by NASA's Jet Propulsion Laboratory in
Pasadena, Calif.
-more-
-16-
The remaining ground stations, except those necessary for
launch operations, will be closed or transferred to other
agencies after the successful launch and checkout of the next two
TDRS satellites.
The ground station network, managed by the Goddard Space
Flight Center, Greenbelt, Md., provides communications support
for only a small fraction (typically 15-20 percent) of a space
craft's orbital period. The TDRSS network, when established,
will provide coverage for almost the entire orbital period of
user spacecraft (about 85 percent).
A TDRSS ground terminal has been built at White Sands, N.M.,
a location that provides a clear view to the TDRSS satellites and
weather conditions generally good for communications.
The NASA ground terminal at White Sands provides the inter
face between the TDRSS and its network elements, which have their
primary tracking and communication facilities at Goddard. Also
located at Goddard is the Network Control Center, which provides
system scheduling and is the focal point for NASA communications
with the TDRSS satellites and network elements.
The TDRSS satellites are the largest, privately-owned tele
communications spacecraft ever built, each weighing about 5,000
lbs. Each satellite spans more than 57 ft., measured across its
solar panels. The single-access antennas, fabricated of molyb
denum and plated with 14K gold, each measure 16 ft. in diameter
and, when deployed, span more than 42 ft. from tip to tip.
The satellite consists of two modules. The equipment module
houses the subsystems that operate the satellite. The telecom
munications payload module has electronic equipment for linking
the user spacecraft with the ground terminal. The TDRS has 7
antennas and is the first designed to handle communications
through S, Ku and C frequency bands.
Under contract, NASA has leased the TDRSS service from
CONTEL, Atlanta, Ga., the owner, operator and prime contractor
for the system.
TRW Space and Technology Group, Redondo Beach, Calif., and
the Harris Government Communications System Division, Melbourne,
Fla., are the two primary subcontractors to CONTEL for spacecraft
and ground terminal equipment, respectively. TRW also provided
the software for the ground segment operation and integration and
testing for the ground terminal and the TDRSS, as well as the
systems engineering.
Primary users of the TDRSS satellite have been the Space
Shuttle, Landsat Earth resources satellites, the Solar Mesosphere
Explorer, the Earth Radiation Budget Satellite, the Solar Maximum
Mission satellite and Spacelab.
-more-
-17-
Future users include the Hubble Space Telescope, scheduled
for launch in mid-1989, the Gamma Ray Observatory and the Upper
Atmosphere Research Satellite.
-more-
-18-
TDRS Spacecraft Configuration
-more-
-19-
TDRS System
-more-
-20-
INERTIAL UPPER STAGE
The Inertial Upper Stage (IUS) will be used to place NASA's
Tracking and Data Relay Satellite (TDRS-C) into geosynchronous
orbit during the STS-26 Space Shuttle mission.
The STS-26 crew will deploy the combined IUS/TDRS-C payload
approximately 6 hours, 13 minutes after liftoff, at a low-Earth
orbit of 160 nautical miles. Upper stage airborne support equip
ment, located in the orbiter payload bay, positions the combined
IUS/TDRS-C into its proper deployment attitude -- an angle of 58
degrees -- and ejects it into low-Earth orbit. Deployment from
the orbiter will be by a spring-ejection system.
Following the deployment, the orbiter will move away from
the IUS/TDRS-C to a safe distance. The IUS first stage will fire
about 1 hour after deployment.
After the first stage burn of 145 seconds, the solid fuel
motor will shut down. After coasting for about 5 hours, 15
minutes, the first stage will separate and the second stage motor
will ignite at 12 hours, 29 minutes after launch to place the
spacecraft in its desired orbit. Following a 103-second burn,
the second stage will shut down as the IUS/TDRS-C reaches the
predetermined, geosynchronous orbit position.
Thirteen hours, 7 minutes after liftoff, the second stage
will separate from TDRS-C and perform an anti-collision maneuver
with its onboard reaction control system.
After the IUS reaches a safe distance from TDRS-C, the
second stage will relay performance data to a NASA tracking
station and then shut itself down 13 hours, 17 minutes after
launch.
The IUS has a number of features which distinguish it from
previous upper stages. It has the first completely redundant
avionics system developed for an unmanned space vehicle. It can
correct in-flight features within milliseconds.
Other advanced features include a carbon composite nozzle
throat that makes possible the high-temperature, long-duration
firing of the IUS motors and a redundant computer system in which
the second computer is capable of taking over functions from the
primary computer, if necessary.
The IUS is 17 ft. long, 9 ft. in diameter and weighs more
than 32,000 lbs., including 27,000 lbs. of solid fuel propellant.
-more-
-21-
The IUS consists of an aft skirt, an aft stage containing
21,000 lbs. of solid propellant which generates 45,000 lbs. of
thrust, an interstage, a forward stage containing 6,000 lbs. of
propellant generating 18,500 lbs. of thrust and an equipment
support section. The equipment support section contains the
avionics which provide guidance, navigation, telemetry, command
and data management, reaction control and electrical power.
The IUS is built by Boeing Aerospace, Seattle, under con
tract to the U.S. Air Force Systems Command. Marshall Space
Flight Center, Huntsville, Ala., is NASA's lead center for IUS
development and program management of NASA-configured IUSs
procured from the Air Force.
TDRS-A was placed into an elliptical Earth orbit by an IUS
in April 1983 during mission STS-6. TDRS-B and its IUS were lost
in the Challenger accident in January 1986.
-more-
-22-
SECONDARY PAYLOADS
Physical Vapor Transport of Organic Solids
3M Company scientists will fly an experiment on STS-26 to
produce organic thin films with ordered crystalline structures
and to study their optical, electrical and chemical properties.
They call the experiment the Physical Vapor Transport of
Organic Solids (PVTOS), a name derived from the method which is
employed to produce organic crystals -- vapor transport.
Engaged in a long-term space research program that will
extend into the Space Station era, 3M's primary objective with
the STS-26 experiment is to build upon the knowledge gained from
an earlier flight of the apparatus aboard Discovery in 1985.
For more than a decade, 3M scientists have conducted
research into ordered organic thin films with an emphasis on
controlling the film's physical structure properties so as to
affect the film's optical, electrical and chemical behavior.
Using the physical vapor transport technique in the micro
gravity environment of low-Earth orbit allows 3M scientists a
unique opportunity to investigate certain materials of interest.
The results could eventually be applied to production of
specialized thin films on Earth or in space.
The PVTOS experiment consists of nine independent cells 12
inches long and 3 inches in diameter. Each cell contains a test
tube-like ampule containing organic material. During space
flight, the organic material is vaporized. Migrating through a
buffer gas, the vaporized material forms a highly ordered thin
film on a flat surface. After the samples are returned to Earth,
3M scientists will study the films produced in space.
The PVTOS experiment, sponsored by NASA's Office of
Commercial Programs, is being conducted by 3M's Space Research
and Applications Laboratory, headed by Dr. Christopher N. Chow.
Dr. Mark Debe is principal investigator with Dr. Earl Cook as co-
investigator.
-more-
-23-
PVTOS art
-more-
-24-
Protein Crystal Growth Experiment
Protein Crystal Growth (PCG) experiments to be conducted
during STS-26 are expected to help advance a technology attract
ing intense interest from major pharmaceutical houses, the bio
tech industry and agrichemical companies.
A team of industry, university and government research
investigators will explore the potential advantages of using
protein crystals grown in space to determine the complex, three-
dimensional structure of specific protein molecules.
Knowing the precise structure of these complex molecules
provides the key to understanding their biological function and
could lead to methods of altering or controlling the function in
ways that may result in new drugs.
It is through sophisticated analysis of a protein in
crystalized form that scientists are able to construct a model of
the molecular structure. The problem is that protein crystals
grown on Earth are often small and flawed. Protein crystal
growth experiments flown on four previous Space Shuttle missions
already have shown promising evidence that superior crystals can
be obtained in the microgravity environment of space flight.
To further develop the scientific and technological founda
tion for protein crystal growth in space, NASA's Office of Com
mercial Programs and Microgravity Science and Applications
Division are co-sponsoring the STS 26 experiments which are being
managed through the Marshall Space Flight Center, Huntsville,
Ala.
During the flight, 60 different crystal growth experiments,
including as many as ten distinct proteins, will be attempted in
an experiment apparatus that fits into one of the Shuttle
orbiter's middeck lockers.
Shortly after achieving orbit, astronauts will initiate the
crystal growing process, which will continue for several days.
The experiment apparatus, being flown for the first time on STS-
26, differs from previous protein crystal payloads in that it
provides temperature control and automation of some processes.
After Discovery's landing, the experiment hardware and pro
tein crystals will be turned over to the investigating team for
analysis. Lead investigator for the research team is Dr. Charles
E. Bugg of the University of Alabama-Birmingham (UAB). Dr. Bugg
is director of the Center for Macromolecular Crystallography, a
NASA-sponsored Center for the Commercial Development of Space
located at UAB.
Five industrial affiliates of the Center will provide samples
to investigate the quality of protein crystals grown in space.
Following post-flight analysis, crystals produced on the flight
-more-
-25-
will be used by the participating industrial scientists for applied
research.
The industrial participants and their experiments are:
Burroughs Wellcome Co., Research Triangle Park, N.C., is
experimenting with the enzyme reverse transcriptase. The enzyme is
a chemical key to the replication of the AIDS virus. More detailed
knowledge of its three-dimensional structure could lead to new drug
treatments for AIDS. The investigators are Dr. Tom Krenitsky,
Burroughs Wellcome Co. and Dr. David Stammers, Wellcome Research
Laboratories.
The Du Pont Company, Wilmington, Del., is conducting two
experiments aimed at growing crystals of proteins important to life
science research. One is isocystrate lyase, a target enzyme for
fungicides. Better understanding of this enzyme should lead to
more potent fungicides to treat serious crop diseases such as rice
blast. The other protein is alpha 1-B, the first totally synthetic
peptide which was recently synthesized by Du Pont to mimic ion
channels in cell membranes. Research on alpha 1-B will lead to a
better understanding of the manner in which cells selectively
regulate the flow of ions such as potassium, sodium, and calcium in
and out of the cell. It has important potential in therapeutics and
diagnostics. Du Pont's principal investigator is Dr. Ray Salemme.
Merck, Rahway, N.J., will fly a sample of elastace, an enzyme
associated with the degradation of lung tissue in people suffering
from emphysema. A more detailed knowledge of this enzyme's
structure will be useful in studying the causes of this debilitating
disease. The company's principal investigator is Dr. Manuel Navia.
Schering-Plough, Madison, N.J., will experiment to grow
crystals of alpha interferon. Interferon, a protein, stimulates the
body's immune system. Marketed as "Intron A," the company's alpha
interferon is approved in the U.S. for treating a cancer, hairy cell
leukemia, and a viral infection, genital warts. It is also approved
overseas for treating these and a number of other cancers and
ailments. The principal investigator is Dr. T.J. Nagabhushan.
Upjohn, Kalamazoo, Mich., is flying two protein samples:
genetically-engineered human renin and phospholipase A2, found in
the venom of the cottonmouth snake. Human renin is produced by the
kidneys and plays a major role in the chemical reaction that
controls blood pressure. Phospholipase performs functions
associated with cell membranes, and a better understanding of it
could lead to improved medications for pain and inflammation.
Upjohns principal investigator is Dr. Howard Einspahr.
-more-
-26-
PCG art
-more-
-27-
Infrared Communications Flight Experiment
Using the same kind of invisible light that remotely controls
our home TV sets and VCRs, mission specialist George "Pinky" Nelson
is to conduct experimental voice communications with his STS-26
crewmates via infrared, rather than standard radio frequency waves.
On a non-interfering basis and during non-critical normal crew
activities requiring voice operations, Nelson will unstow the
Infrared Communications Flight Experiment (IRCFE) from the middeck
locker and begin a minimum of 2 hours of experimentation from both
flight- and middeck locations.
Six small infrared transmitters and receivers (three each) will
be attached by velcro to Discovery's walls: two each on the flight
deck and one each on the middeck. The transmitters and receivers
are connected by cable to a base unit which also will be attached by
velcro to a middeck wall. Nelson will plug his standard lightweight
headset into a belt-mounted unit which will transmit his voice via
infrared lightwaves through the receivers to the base unit. There,
the signal will be relayed to other crew members using the standard
Orbiter audio distribution system. Communications back to Nelson
from the other astronauts will travel by the reverse path.
One major objective of the experiment is to demonstrate the
feasibility of the secure transmission of information via infrared
light. Unlike radio frequency (RF) signals, infrared waves will not
pass through the orbiter's windows; thus, a secure voice
environment would be created if infrared waves were used as the sole
means of communications within the orbiter. Infrared waves also can
carry data as well as voice (e.g., biomedical information). Future
infrared systems are expected to be smaller, lighter weight and
produce better voice quality than their RF counterparts.
A clear line-of-sight path is not required between transmitter
and receiver to insure voice transmission. Infrared light will
reflect from most surfaces and therefore, quality voice can be
transmitted even after multiple bounces. As Nelson moves around the
vehicle, another major objective is to demonstrate a "flooded volume
approach," that is, to see if the wall-mounted
transmitters/receivers will pick up and deliver infrared signals
without the need for him to precisely align his transmitter with a
target receiver.
The amount of coverage and/or blockage which occurs during the
experiment under microgravity conditions is a critical objective of
the experiment. Comments by Nelson and his crewmates on the
effectiveness and quality of the system will be relied on heavily.
Post-flight analysis of the infrared system's voice quality also
will be made through tape comparisons.
-more-
-28-
IRCFE art
-more-
-29-
While the IRCFE calls for a minimum of 2 hours of experimenta
tion, there are no constraints on continuing use of the system
beyond that time. However, the experiment must be restowed in its
locker prior to descent. The 20-lb. IRCFE package, which includes a
complete back-up unit, fits in less than 1/2 of a 2-cubic-ft.
middeck locker.
If proven effective, the technique of using infrared light as a
voice and information carrier could have widespread application
including incorporation in the Shuttle, Spacelab and the Space
Station as well as potential non-NASA uses in military aircraft,
naval ships and Army combat vehicles.
The IRCFE was developed at a cost of approximately $500,000 by
Johnson Space Center, Houston, and its contractor, Wilton
Industries, Danbury, Conn. Project manager and principal inves
tigator for the experiment is Joseph L. Prather, of the Engineering
Directorate's Tracking and Communications Division at JSC.
Automated Directional Solidification Furnace
The Automated Directional Solidification Furance (ADSF) is a
special space furnace developed and managed by Marshall Space Flight
Center. It is designed to demonstrate the possibility of producing
lighter, stronger and better-performing magnetic composite materials
in a microgravity environment.
Four furnace modules are included in the ADSF, each processing
a single sample. The samples being used during the STS-26 mission
are manganese and bismuth composites. They will be processed at a
constant melting and resolidification speed of one about a third of
an inch an hour. The total process times will be 10.5 hours per
sample.
Material processed during the mission will be compared with
samples of the same metallic alloys processed in laboratories on
Earth, as well as from previous Shuttle and sounding rocket
flights. Thermal, X-ray, chemical, structural and magnetic analysis
will be made following the flight to determine differences in the
various samples.
The furnace is specially designed to melt along a plane in a
long, slim, magnetic composite sample and then cool the molten metal
behind the melt. The furnace module traverses the sample in a
single direction, melting and then resolidifying the material as it
goes.
The ADSF flight hardware is housed in three separate containers
connected by power and data cables. The four furnaces are housed in
one container; another container has the electronic assembly which
controls furnace operations and yet another houses the control
switches, status indicators and a system which records data produced
during the operation of the furnaces.
-more-
-30-
ADSF art
-more-
-31-
The total flight package weighs about 250 lbs. and occupies the
space of five crew lockers in the orbiter middeck. The equipment is
highly automated and requires crew interaction only to initiate the
operation of the furnaces.
All the ADSF hardware is reusable. The furnace apparatus was
first flown aboard sounding rockets. It has been modified to be
compatible with the orbiter and crew interface requirements and to
increase the furnace operating time.
Each furnace can now operate up to 20 hours, compared to a
total of 5 minutes during the sounding rocket flights. The exper
iment most recently flew aboard STS 51-G.
Principal investigator for this experiment is Dr. David Larson,
Grumman Aerospace Corp. MSFC manages the development of the
hardware and provides mission integration management for NASA.
Project manager is Fred Reeves, MSFC, and mission manager is Richard
E. Valentine, also MSFC.
Aggregation of Red Blood Cells
Blood samples from donors with such medical conditions as heart
disease, hypertension, diabetes and cancer will fly in an experiment
called Aggregation of Red Blood Cells (ARC) developed by Australia
and managed by MSFC.
The experiment is designed to provide information on the
formation rate, structure and organization of red cell clumps, as
well as on the thickness of whole blood cell aggregates at high and
low flow rates. It will help determine if microgravity can play a
beneficial role in new and existing clinical research and medical
diagnostic tests.
The first ARC experiment flew aboard STS 51-C in January
1985. The STS-26 experiment differs from its predecessor only in
the samples tested. The experiment hardware is unchanged.
The flight hardware weighs about 165 lbs. and is installed in
three middeck lockers in the crew cabin. The experiment consists of
a blood pump and storage subsystem, thermal control system, pressure
transducer and an electronics equipment package to provide automated
control and data acquisition.
The ARC experiment uses eight experiment blood samples main
tained at about 40 degrees F. Each flows one sample at a time, into
a viscometer, two optically transparent polished glass plates
separated by a spacer of platinum foil.
Two 35mm cameras, located on either side of the viscometer,
photograph the samples through 10x and 300x power microscopes. The
10x power microscope uses black and white film and the 300x power
uses color.
-more-
-32-
ARC art
-more-
-33-
After taking the photographic and low-rate data, the sample is
discarded in a waste container. A saline solution, stored in
syringes identical to those containing the blood samples, is then
used to flush the system prior to running the next sample.
All procedures are operated by the electronic equipment package
except activation which is performed by one of the crew. Running
time is about 8 hours.
Results obtained in the Shuttle microgravity environment will
be compared with results from a ground-based experiment to determine
what effects gravity has on the kinetics and morphology of the
sampled blood. The ground-based experiment will be conducted
simultaneously with the flight experiment using samples identical in
origin to the flight samples and functionally identical hardware.
The experiment and hardware were developed by Dr. Leopold
Dintenfass of the Kanematsu Institute, Department of Medical
Research, Sydney, Australia. Richard E. Valentine, MSFC, is mission
manager.
Isoelectric Focusing
Isoelectric Focusing (IEF) is a type of electrophoresis
experiment which separates proteins in an electric field according
to their surface electrical charge.
Three other electrophoresis experiments have flown before on
Shuttle missions. They were the McDonnell Douglas Continuous Flow
Electrophoresis System, NASA's Electrophoresis Equipment
Verification Test and an earlier version of the IEF.
The isoelectric focusing technique applies an electric field to
a column of conducting liquid containing certain molecules which
create a pH gradient in the column (alkalinity at one end, acidity
at the other end). This pH gradient causes the biological sample to
move to a location in the column where it has a zero charge - its
isolectric point.
Protein and fluid-filled experiment columns are provided by the
University of Arizona. The remainder of the flight hardware was
designed and built by laboratory personnel at MSFC, which is
providing mission management.
The 65-pound experiment consists of eight glass columns
containing protein, hemoglobin and albumen, with solutions which
form the pH gradient column of conducting liquid.
The columns are arranged in a row in the field of view of a 35
mm camera. The experiment is housed in a 9-inch-high, 19 by 21-inch
rectangular metal container and is installed in place of a middeck
locker in the crew cabin.
-more-
-34-
IEF art
-more-
-35-
A crewmember will activate the equipment 23 hours into the
flight. The experiment will operate for 90 minutes with pictures of
the separations being taken every 2 or 3 minutes. The crew member
will return to the experiment hardware at the end of the running
time to verify that it has successfully turned itself off.
The film from the experiment camera will be removed for
processing upon orbiter landing. The samples themselves are not
required for post-mission analysis.
Principal investigator on the experiment is professor Milan
Bier of the University of Arizona. Co-investigator is Dr. Robert
Snyder of the Separation Processes Branch at MSFC's Space Science
Laboratory. Richard E. Valentine, MSFC, is the mission manager and
Brian Barnett, MSFC, is the experiment coordinator.
Mesoscale Lightning Experiment
Mesoscale Lightning Experiment (MLE) is an experiment designed
to obtain night time images of lightning in an attempt to better
understand the effects of lightning discharges on each other, on
nearby storm systems and on storm microbursts and wind patterns and
to determine interrelationships over an extremely large geographical
area.
The experiment will use Shuttle payload bay cameras to observe
lightning discharges at night from active storms. The experiment
uses color video cameras and a 35mm hand-held film camera and will
provide synoptic coverage of an area roughly 200 by 150 miles
directly below the Shuttle.
Shuttle crewmembers also will document mesoscale storm systems
that are oblique to the Shuttle but near NASA ground-based lightning
detection systems at Marshall Space Flight Center, Kennedy Space
Center, Stennis Space Center (formerly National Space Technology
Laboratories), and the National Oceanic and Atmosphere
Administration Severe Storms Laboratory, Norman, Okla.
The Shuttle payload bay camera system provides camera orien
tation data so that the locations and dimensions of the lightning
discharges recorded can be easily determined from the video and film
images. The imagery will be analyzed for the frequency of flashes,
the size of the lightning and its brightness.
Three co-investigators will analyze the lightning data taken
from the Shuttle as well as corroborate information received from
the ground-based lightning monitoring network. They are Dr. Bernard
Vonnegut, State University of New York, Albany; Dr. Max Brook, New
Mexico Institute of Mining and Technology, Socorro; and Otha H.
Vaughan Jr., MSFC. Richard E. Valentine, MSFC, is the mission
manager.
-more-
-36-
Phase Partitioning Experiment
One of the most important aspects of biotechnical and bio
medical technology involves separation processes. Cell types
producing important compounds must be separated from other cell
types. Cells with important biomedical characteristics must be iso
lated to study those characteristics. This experiment involves a
separation method termed two-phase partitioning.
The Phase Partitioning Experiment (PPE) is designed to fine
tune understanding of the role gravity and other physical forces
play in separating, i.e., partitioning biological substances between
two unmixable liquid phases.
Most people are use to the two-phase systems formed by mixing
oil and water. In PPE, the systems are simple saline solutions
containing two different polymers. When the polymers are dissolved
in solution, they separate. On Earth this results in the lighter
phase floating on top of the heavier one. In space the demixed
phases exhibit more complex behavior, looking somewhat like an egg
which has a yolk floating inside of the egg white.
Phase partitioning has been shown on Earth to yield more
effective, large-scale cell separations than any other method,
differentiating cells on the basis of their surface properties.
Space experiments should improve efficiency of Earth-bound par
titioning and may allow scientists to carryout cell separations
unobtainable on Earth.
The experiment is part of a category of handheld microgravity
experiments designed to study the effects of the low gravity of
spaceflight on selected physical processes.
The experiment consists of an 18-chambered experimental module
filled with small quantities of two-phase systems, each differing in
various physical parameters (e.g. viscosity). The module will be
shaken to mix the phases and the separation of the phases will be
photographed periodically by a mission specialist.
The experiment will last approximately 2 hours. The 0.7
kilogram module is completely self-contained and will be stored in
one of the middeck storage lockers.
Photos of the separation will be taken with a 35mm Nikon camera
equipped with an hour/minute/second time-tag using a 35-70mm
macrozoom lens. The photos will be studied when they are returned
to Earth and analyzed by computer-aided densitometry for demixing-
versus-time-kinetic information.
A 15-chamber version of the PPE was successfully flown on STS
51-D, and the experiment is being considered for at least two more
flights.
-more-
-37-
PPE art
-more-
-38-
The experiment was developed and is being managed by the
Marshall Space Flight Center, Huntsville, Ala. The project is
sponsored by NASA's Microgravity Science and Applications
Division.
The PPE scientific team includes Drs. Donald E. Brooks,
principal investigator, University of British Columbia; J. Milton
Harris, University of Alabama-Huntsville; James M. Van Alstine,
Universities Space Research Associates at Marshall; Stephen
Bamberger, National Research Council; and Robert S. Snyder,
Marshall. Richard E. Valentine is the mission manager for PPE at
Marshall.
Earth-Limb Radiance Experiment
Earth Limb Radiance Experiment (ELRAD) is an experiment
developed by the Barnes Engineering Co., designed to photograph the
Earth's "horizon twilight glow" near sunrise and sunset.
The experiment is expected to provide photographs of the
Earth's horizon that will allow scientists to measure the radiance
of the twilight sky as a function of the sun's position below the
horizon. This information should allow designers to develop better,
more accurate horizon sensors for geosynchronous communications
satellites.
Communications satellites routinely use the Earth's horizon or
"limb" as a reference for attitude control. Barnes Engineering is
developing an advanced horizon sensor that uses visible light to
sense the Earth's limb. Near the spring and fall equinoxes,
however, the Earth eclipses the sun once a day (as seen from the
satellites' orbit), often for as long as 70 minutes.
During these eclipses, the Earth's horizon is invisible to a
visible light horizon sensor. However, the Earth's upper atmosphere
scatters sunlight to produce a thin ring of blue and ultaviolet
light that would still be visible even during an eclipse. This ring
of light is what ELRAD will photograph.
ELRAD consists of a 35mm Nikon camera, an 85mm lens, a blue
lens filter and a timing device known as a intervalometer.
Astronauts onboard the Space Shuttle will mount ELRAD in one of the
Shuttle's windows and point it toward the Earth's horizon. The
intervalometer will be set to take one photograph every 10
seconds. Three sequences of photographs will be taken, one just
before sunrise and two just after sunset. After the mission, the
exposed film will be developed by NASA and provided to Barnes
Engineering, along with a sensitivity curve. Barnes Engineering
will then compute the radiance of the scattered light as recorded on
the film.
-more-
-39-
Principal investigator for ELRAD is William Surette, Barnes
Engineering. Johnson Space Center manages the mission integration
for NASA. The payload integration manager is Ed Jung and the
mission manager is Willie Beckham, both from Johnson.