Volume 4, Number 2 May/June 1996
Most of the payloads-over 90 percent-aboard Space Shuttle Endeavor on STS-77 are being sponsored by the NASA's Office of Space Access and Technology (OSAT). Primary payloads include experiments flying aboard the pressurized, commercially-developed SPACEHAB Module (see page 15); an Inflatable Antenna Experiment to be deployed aboard the free-flying Spartan-207 carrier spacecraft (see page 18); and a bundle of four technology experiments (two sponsored by OSAT), known as "TEAMS".
Additionally, other experiments that will be aboard STS-77 include a BETSCE cryocooling experiment (see this page below) and a cryogenic tank pressure control experiment.
Technology Experiments Advancing Mission in Space (TEAMS)
The TEAMS payload consists of a Hitchhiker carrier that carries equipment mounted in canisters but also has mounting plates of various sizes for user equipment. OSAT is managing two (VTRE and PAMS) of the four experiments on TEAMS.
The Vented Tank Resupply Experiment (VTRE), managed by Lewis Research Center, will investigate, develop, and acquire data on tank venting. The absence of gravity combined with the natural tendency of liquids to wet, solid surfaces makes it difficult to vent or resupply tanks with gas and liquid because the location of each cannot be reliably predicted. Capillary vane devices will be tested that will enable direct tank venting and resupply of partly filled tanks by locating and concentrating the liquid. VTRE will test efficient and reliable management of fluids with respect to gas venting and vented liquid resupply. The VTRE flight operations require a minimum of 24 hours total operating time and consist of eight groups of tests.
The Passive Aerodynamically-Stabilized Magnetically-Damped Satellite (PAMS), managed by Goddard Space Flight Center, is a technology demonstration of aerodynamic stabilization which can be used to point a satellite in the direction of flight while in low-Earth orbit. Aerodynamic stabilization is the same principle that controls the flight of a dart (the front is weighted and will always point itself with the head facing forward). Most satellites need direction control to point at a specific feature that will be measured from space. Designing satellites that use this principle should allow a simpler attitude control system, making the satellite less complicated, more reliable, and cost-effective. The experiment has two parts: a small satellite will be deployed from the Space Shuttle and will aerodynamically stabilize in flight and a measuring system, located in the cargo bay of the Shuttle, will observe and record PAMS' motion during the mission.
Reduced-Fill Tank Pressure Control Experiment (RFTPCE)
The RFTPCE is designed to determine the effects of microgravity on the thermal stratification of fluids and to validate the effects of jet induced mixing. Future space missions will require storage of cryogenic fluids in a microgravity environment for extended periods of time. Heat leaks to the containment vessel lead to an increase in the temperature and pressure of the fluid. The absence of natural convection results in a non-uniform fluid temperature which exacerbates the pressure increase. Therefore, a re-circulation liquid jet is necessary to mix the fluid. The RFTPCE will aid in the prediction of heat and mass transfer rates of fluid management systems in a microgravity environment. The experiment will be housed in a Get-Away Special (GAS) canister, which is mounted in the Shuttle payload bay on the sidewall or on a cross-bay truss structure.
