Space Technology Development
On Day Two of the STS-77 mission, the Endeavour crew
deployed the first of two satellites to be released from the
Orbiter, to conduct a major event of the 10-day flight; the Inflatable
Antenna Experiment (IAE).
The IAE was designed to lay the groundwork for future technology
developments in inflatable space structures, which have potential
to be 10 to 100 times less expensive than conventional structures.
The experiment was carried aboard the 1,866-pound Spartan 207,
a multipurpose free-flying satellite that is deployed from the
Orbiter and retrieved by an astronaut operating the Shuttle's
Remote Manipulator System. Managed by Goddard Space Flight Center,
the carrier version of the Spartan was making its second flight;
overall it was the eighth Spartan mission flown on the Space
Shuttle.
Pictured against the backdrop of St. Louis and the Mississippi
River, this large antenna was released by the free-flying Spartan
207 satellite in an STS-77 investigation of the potential of
inflatable space structures. It was fitted into Spartan as a
compact 132-pound package, then inflated into a 50-foot-diameter,
92-feet-long structure.
Packed into the Spartan, the IAE weighed only 132 pounds;
on deployment (inflation), it would expand to an antenna 50-feet
in diameter mounted on three 92-foot struts. The IAE was developed
by L'Garde Inc., Tustin, California and Jet Propulsion Laboratory
under NASA's In-Space Technology Experiment Program.
Spartan was released on May 20; the antenna was successfully
deployed and it achieved the proper configuration. The inflation
process was captured by the STS-77 crew on still, motion picture
and video cameras. For post-mission analysis of the inflatable
structure's performance, the antenna surface was illuminated
by arrays of lights mounted on the Spartan satellite and the
resulting patterns were acquired by Spartan's video recorders.
After 90 minutes of operation, the IAE was jettisoned; the Spartan
was grappled and retrieved the following day.
On May 23, Day Four, the Endeavour crew deployed the
second satellite, this one known as PAMS, for Passive, Aerodynamically-stabilized
Magnetically-damped Satellite. The PAMS experiment consisted
of the small (115 pounds) satellite and a measuring system that
enabled the crew to observe the satellite's motions after deployment
from the Orbiter. The experiment was a demonstration of aerodynamic
stabilization, a technique that can be used to position a satellite
in a specific orientation while in low Earth orbit.
This view of the Orbiter Endeavour's stern shows the Spartan
207 free flyer being recaptured after a day-long research trip
away from the Orbiter. It is being jockeyed toward its stowage
berth by an astronaut operating the remote manipulator system.
The PAMS satellite was spring-ejected from Endeavour's
payload bay as cameras in the Orbiter recorded the deployment.
For most of the next five days, the Orbiter trailed the 20-inch
satellite at a distance of about 2,000 feet while the Shuttle
crew used the measurement system to note the damping (stabilization)
motions of the satellite. Video and radar data were acquired
throughout the station-keeping period.
PAMS was one of four experiments in the TEAMS group of payloads
mounted in Goddard Space Flight Center's Hitchhiker experiment
carrier in Endeavour's cargo bay. The others were:
- The Global Positioning System (GPS) Attitude and Navigation
Experiment, a test of how accurately the GPS constellation of
positioning satellites can determine the attitude of a vehicle
in an orbital environment. The International Space Station will
use GPS for attitude determination as well as velocity and time
information.
- The Vented Tank Resupply Experiment, which tested improved
methods for in-space refueling to provide data for future designs
of spacecraft liquid fuel storage tanks. Lewis Research Center
and contractor Lockheed Martin developed the experiment.
- The Liquid Metal Thermal Experiment, an evaluation of the
performance of liquid metal heat pipes in microgravity conditions.
Heat pipes are thermal management devices used on many existing
spacecraft for waste heat removal. However, the operational characteristics
of heat pipes are not completely understood, because they have
not been operated at high temperatures in microgravity. The three
heat pipes in this experiment contained potassium and operated
at very high temperatures, 300 to 1000 degrees Celsius. The data
obtained will be invaluable to designers of space systems requiring
high temperature heat rejection.
STS-77, an eventful and highly productive space technology
development mission, ended on May 29 when Endeavour touched
down at Kennedy Space Center after a flight of 10 days and 39
minutes.
STS-77 astronauts Marc Gameau (foreground) and Curtis L. Brown,
Jr. check out the audio system of the SPACEHAB Space Research
Laboratory. SPACEHAB is a commercially-developed pressurized
facility carried in the Shuttle Orbiter's payload bay.
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