Design and Performance of the Cryogenic Two Phase Flight Experiment (CRYOTP)

This paper summarizes flight test results which were obtained in the Cryogenic Two Phase Flight Experiment (CRYOTP). This was a HitchHiker canister experiment that was flown aboard the space shuttle Columbia in March of 1994.

Two flight articles were tested independently. The first was a nitrogen heat pipe with five parallel fibrous copper cable wicks. It did not startup in either of two cooldown cycles. Post flight inspection of the heat pipe showed that it had its original fluid charge. The failure to startup is attributed to the large fluid inventory and the conduction gradient that existed due to nominal parasitic heat leaks along the titanium heat pipe tube. Complete success was obtained with the Brilliant Eyes Thermal Storage Unit (BETSU) which contains 2-methylpentane phase change material for temperature control at 120K. More than 200 hours of on orbit tests consisting of several cooldown cycles and 55 freeze/thaw cycles was obtained with BETSU. Degradation of the five tactical coolers that are flown in the CRYOTP was also observed. One of the coolers on the NHP side of the experiment failed completely, apparently due to leakage of the helium working fluid.