The Cryogenic InfraRed Radiance Instrumentation for Shuttle (CIRRIS 1A) instrument, successfully flown and operated on the Shuttle Discovery from 28 April to 6 May 1991, was designed to operate at supercritical helium temperatures. During flight, the focal plane temperature control and telescope contamination purge systems performed as designed and 36 hours of excellent data was obtained; however, the parasitic helium flow rate was higher than expected. This paper reviews thermal data obtained for the CIRRIS 1A cooling system during both ground and flight operations. The temperature control and purge systems are discussed, along with helium flow rates, dewar helium pressure, and thermal stratification. In addition, possible reasons for the high on-orbit parasitic flow rate are presented.