.POST-FLIGHT ANALYSIS OF A 10 K SORPTION CRYOCOOLER

In May 1996, the Brilliant Eyes Ten-Kelvin Sorption Cryocooler Experiment (BETSCE) was flown aboard the Space Shuttle flight STS-77 in the first space-flight demonstration of chemisorption cryocooler technology. While on orbit, BETSCE successfully met its science objectives of cooling from 70 K to 10 K in less than two minutes, sustaining a 100 n~W heat load below 11 K for over ten minutes, and demonstrating recycle times of approximately eleven hours. The hydride compressors were able to circulate and compress the hydrogen refrigerant fluid in a repeatable manner with no adverse microgravity effects being observed Since completion of the Shuttle flight, the BETSCE flight hardware was carefully inspected and a repair was made to a system valve which had developed an internal leak during flight. A series of successful cooldown cycles to below 9.5 K were completed during post-flight ground tests following repair of this valve. All observed compressor and cryostat parameters obtained in the measurements petiormed afier flight were entirely consistent with the behavior seen in the pre-flight tests. These results verify that key functional performance of the BETSCE instrument is highly reproducible and did not degrade throughout the extensive ground tests and flight operation