Flight test results of the SHARE II monogroove heat pipe

The SHARE II (Space Station Heat Pipe Advanced Radiator Elements) flight experiment was flow in August 1991 on STS-43 in support of the Space Station Freedom (SSF) program. The flight experiment was designed to demonstrate startup and sustained microgravity operation of two 22 ft. long high capacity prototype SSF heat pipe radiator designs. The monogroove heat pipe radiator, one of the two heat pipe radiator designs flown on this experiment, is the subject of this paper. During the flight, the monogroove heat pipe, which contained 40 to 50 ppm of noncondensible gas to simulate end-of-life conditions, was shown to start up, vent bubbles as necessary, reprime under load, and operate successfully under all test conditions. The monogroove heat pipe operated under load for a total of 75 hours and achieved sustained heat transport of 50,000 watt-inches. This paper briefly describes the results of the previous SHARE flight experiment and the improvements made to the monogroove heat pipe as a result of that experiment. The test results of the SHARE II flight are discussed in detail. Based on the results of the SHARE II experiment, the monogroove heat pipe is ready for use in its intended application on SSF.