Kennedy Space Center, Fla., May 17, 1996 A Boeing experiment is expected to provide valuable data for future spacecraft design following its return from Space Shuttle Endeavour's STS-77 mission. Endeavour is scheduled to launch May 19 on a nine-day mission.

The project, titled Tank Pressure Control Experiment (TPCE), is part of a joint effort by the University of Cincinnati and Boeing Defense & Space Group to develop new technology for low-gravity cryogen storage tanks required for future space missions. As it rides in the shuttle's cargo bay, the TPCE will measure and record data from its Freon-filled plexiglass tank while Endeavour orbits the Earth.

"Controlling storage tank pressures in microgravity is one of the thornier issues that needs to be solved for in-space use of cryogenic fluids," said Michael Bentz, Boeing TPCE program manager. "The Space Shuttle is an unrivaled test facility for performing this kind of research, and using small self-contained payloads allows it to be done cost-effectively."

Cameras inside the barrel-sized package will record the Freon test fluid's motion over a 25-hour span to determine how to most-effectively mix the liquid with a very gentle, low-energy mixer jet, Bentz said.

The experiment is designed to operate with a minimum of astronaut interaction. During the shuttle's ascent to orbit, reduced atmospheric pressure will activate a barometric switch that powers up the payload. The crew will observe the experiment prior to the astronauts' first sleep period to ensure it is powered.

The second day after launch, the experiment completes its sequence and turns itself off, and the crew disconnects its batteries. The payload will return to Kennedy Space Center's Orbiter Processing Facility following the shuttle's mission completion. There, NASA technicians will remove the payload carrier from the orbiter and deliver it to the Space Station payloads processing facility. Engineers from Boeing will "take a quick look" at the videotaped information, Bentz said, and will gather video and digital data for future study in Seattle.

Likely to benefit from TPCE's revealing data, according to Bentz, are new cryogenic-fueled upper stages and future space vehicles for lunar and Mars transportation.

This flight _ the third for the payload _ is designated "TPCE/Reduced Fill Level," according to Bentz.

"The first two flights successfully demonstrated effective and efficient pressure control on tanks that were nearly full," Bentz said. "This time a partially empty tank will be tested by reducing the test fluid quantity. This will aid in designing multiple-burn upper stages, for example, that require long coast periods between the burns."