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The Earth Observing-1 (EO-1) spacecraft is the first earth orbiting spacecraft in NASA's New Millennium Program. The New Millennium Program is part of the agency's Mission to Planet Earth enterprise, a series of space missions designed to enhance our knowledge of the Earth and its environmental systems. The EO-1's mission is to employ advanced remote-sensing technologies, including hyperspectral and multispectral imaging techniques, to develop highly accurate terrestrial images. In order to accomplish this mission, the spacecraft contains three primary instruments: Advanced Land Imager (ALI), Atmospheric Corrector, and Hyperion. The bus supporting these sensors is part of a 3-axis stabilized, nadir pointing spacecraft that employs an articulating solar array to provide a constant voltage, regulated power bus. EO-1 also contains several new technologies such as a carbon-carbon radiator and a pulsed plasma thruster that will be verified as part of the secondary mission objectives.

This paper describes the Cryogenic Capillary Pumped Loop (CCPL) flight experiment, which flew as part of the CRYOTSU payload on STS-95 in late 1998. The CCPL flight unit is a miniaturized two-phase fluid circulator for transporting cooling power from cryogenic cooling sources (cryocoolers) to remote cryogenic components. During the 9-day flight, the N2-charged CCPL operated successfully over six test cycles (~70 hours). Heat loads were varied from 0-3 W and tests included several startups, power cycles, cold reservoir set-point tests, and condenser sink temperature tests. Ground and flight test data is included herein. The zero-g environment had no discernible impact on CCPL operation.

This paper describes the flight test results of the fifth generation cryogenic capillary pumped loop (CCPL-5) which flew on the Space Shuttle STS-95 in October of 1998 as part of the CRYOTSU Flight Experiment. This flight was the first in-space demonstration of the CCPL, a lightweight heat transport and thermal switching device for future integrated cryogenic bus systems. The CCPL-5 utilized nitrogen as the working fluid and operated between 75K and 110K. Flight results indicated excellent performance of the CCPL-5 in a micro-gravity environment. The CCPL could start from a supercritical condition in all tests, and the reservoir set point temperature controlled the loop operating temperature regardless of changes in the heat load and/or the sink temperature. In addition, the loop demonstrated successful operation with heat loads ranging from 0.5W to 3W, as well as with parasitic heat loads alone.