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Loop Heat Pipes (LHPs) have been base-lined for thermal management in the next generation of large communication satellites due to their ability to effectively transport energy using two-phase heat transfer. To incorporate LHPs in thermal design, a subroutine was developed to work with a nodal thermal analyzer for transient predictions of LHP operating temperatures. The thermal analyzer (e.g., SINDA or IDEAS/TMG) is used to advance the thermal solution in time, while the subroutine provides the time-varying fluid boundary conditions and adjusts thermal couplings by solving the conservation equations of mass, momentum and energy. The subroutine was exercised in conjunction with a nodal thermal analyzer to predict the fluid temperatures in a loop heat pipe during transient changes in power and sink temperature. A laboratory test was performed with an ammonia LHP to collect data for verifying the model.

The Near Earth Asteroid Rendezvous (NEAR) mission is the first launch in the Discovery Program, a NASA initiative for small planetary missions. Following the launch aboard a 7925 Delta II, and nearly three years of semi-dormant cruise mode, the NEAR spacecraft will rendezvous with and orbit the near-Earth asteroid 433 Eros. While orbiting 433 Eros, NEAR will conduct the first systematic scientific exploration of an asteroid by measuring its bulk, surface, and internal properties. In order to accomplish this task, the NEAR spacecraft contains a suite of sensors comprised of an Infrared (IR) Spectrometer, a Multispectral Imager/Spectrometer, an X-Ray/Gamma-Ray Spectrometer, a Magnetometer, and a Laser Rangefinder. The structure supporting these sensors is part of a 3-axis stabilized, solar-oriented spacecraft that employs fixed coplanar solar arrays to provide a constant voltage, regulated power bus.