Space Access and Technology
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.