Patrick J. Brennan

Design and Performance of the Cryogenic Flexible Diode Heat Pipe (CRYOFD) Flight Experiment

Abstract : The first space flight cryogenic flexible diode heat pipes were developed and verified under micro-gravity conditions on the Space Shuttle during STS-94 (July 1997) and the previous, minimum mission STS-83 (March 1997). The heat pipe working fluids were oxygen (with an operating range of 60 to 145 K) and niethane (95 - 175 K). The heat pipes were verified as part of the Cryogenic Flexible Diode Beat Pipe (CRYOFD) flight experiment. CRYOFD was the third and fourth flights of the Hitchhiker based Cryogenic Test Bed.

Development of an integrated cryogenic bus for spacecraft applications

To improve the efficiency and reduce the overdesign penalties associated with integrating cryogenic systems into spacecraft, the Integrated Cryogenic Bus (ICB) program was initiated in April 1996. The technical objectives of the program were to develop an integrated, lightweight means of thermally linking a cryogenic cooling source to a cooled satellite component, to commonize the interfaces to the cooling source and cooled component, and to commonize the integration of these systems into spacecraft. The technical plan involves several steps beginning with the definition of requirements, the identification and characterization of potential bus components, the development of new concepts and optimization methods, breadboard testing, and prototype development. Six months into the program, over 25 cryocooler, focal plane, and cryogenic hardware organizations have been interviewed or surveyed to identify requirements, numerous components have been identified and characterized, several preliminary concepts hav...

Flight data for the Cryogenic Heat Pipe (CRYOHP) Experiment

This paper presents the flight test results and data correlation for the Cryogenic Heat Pipe Flight Experiment (CRYOHP). CRYOHP is a Hitchhiker Canister experiment that was flown aboard the shuttle Discovery (STS-53) in December of 1992. Two different axially grooved oxygen heat pipes were tested to determine their startup behavior and transport capability in micro-gravity. Three startup cycles were conducted with each heat pipe and transport data was obtained over the range of 60 K to 140 K. Startup in flight was repeatable but slower than observed in ground tests. The transport data shows good agreement with the theoretical model. The CRYOHP test bed, which incorporates five Stifling cycle refrigerators to provide the cryo-cooling, performed as predicted and offers a good micro-gravity test bed for cryogenic thermal devices. 6 refs.

Summary of test results for the cryogenic two-phase flight experiment

This paper presents a brief summary of the flight results for the Cryogenic Two-Phase Flight Experiment (CRYOTP). This experiment was a Hitchhiker-based payload that flew on the space shuttle Columbia in March of 1994 (STS-62). CRYOTP tested two new technologies for advanced cryogenic thermal control; the Space Heat Pipe (SHP), which was a constant conductance cryogenic heat pipe, and the Brilliant Eyes Thermal Storage Unit (BETSU), which was a cryogenic phase-change thermal storage device. Both devices were tested independently during the mission. Analysis of the flight data indicated that the SHP was unable to start in either of two attempts, due to a supercritical startup limit related to the wall material thermal conductivity, parasitic heat leaks, and cryocooler capacity. The BETSU test article was successfully operated with more than 250 hours of on-orbit testing including several cooldown cycles and 56 freeze/thaw cycles. Some degradation was observed with the five tactical cryocoolers used as thermal sinks, and one of the cryocoolers failed completely after 331 hours of operation. Post-flight analysis indicated that this problem was most likely due to failure of an electrical controller internal to the unit. {copyright} {ital 1996 American Institute of Physics.}

Performance of the Cryogenic Heat Pipe Experiment

The Cryogenic Heat Pipe (CRYOHP) Experiment has been designed to test two cryogenic heat pipes independently in a micro-gravity environment. The CRYOHP experiment is manifested for flight aboard the shuttle (STS-53) which is scheduled for launch in November, 1992. This paper presents the design of this experiment and the thermal vacuum verification test results. A correlation of the test data and the planned mission operations are also provided. 4 refs.