Advanced Thermal-Control Systems as Applied to Future NASA Spacecraft 851354
A design study of pumped two-phase and capillary-pumped thermal control systems (TCS) was conducted on a typical, advanced earth-orbiting spacecraft (AEOS). NASA's Upper Atmosphere Research Satellite (UARS) size and baseline design were chosen as the configuration for AEOS; however, the power requirements were increased and the allowable temperature range was decreased to represent the requirements of a more advanced spacecraft.
For peak-power dissipations of 1 or 2 kW, the capillary-pumped system was lightest. At these power dissipations, the line sizes were the smallest available: therefore, there was no net advantage to having a pump. The 91kg weight saving over the 173kg conventional system was due primarily to reduced heater power. However, more convenient component locations also reduced the structural weight significantly. In addition to the weight advantage, the more nearly isothermal spacecraft obtainable with the two-phase system permits less compensation for thermal distortion; a simpler, less costly structure results.