Description: As NASA adventures back to the moon with its sight on the South Pole, spacecraft thermal designers are faced with the unprecedented challenge of surviving extended excursions on the cold and frigid environment of the lunar night, potentially using only resistive heating. The proposed Phase IIE and Phase III programs will develop thermal architectures for Lunar Landers and Rovers with the objective of optimizing power requirements for extended lunar night survival. The Principal Objective of the proposed Phase IIE/III programs is to provide flight-like thermal control systems that will be used to validate the thermal design of the NASA VIPER rover. The components can be combined into the following Engineering Demonstration Units for the VIPER Lunar Rover: Heat Spreader/PCM Module/Cold Reservoir VCHP/Radiator Heat Spreader/PCM Module/Warm Reservoir VCHP/Radiator Heat Spreader/PCM Module/Conventional LHP with TCV/Radiator Heat Spreader/PCM Module/3D Printed LHP with TCV/Radiator These devices will be incorporated into variable link thermal architectures that allow the Lander/Rover to easily dissipate heat while in the Lunar sunlight. They will minimize the heat leaks during the Lunar night, and during travel into dark Lunar craters. For solar powered systems, minimizing electrical power usage at night is extremely important, since 1 W of power over the entire night requires 5 kg of solar cells, batteries, etc. Manned systems will be required in the near future. These devices must also act in microgravity, during transit between the Earth and the Moon. The microgravity thermal control systems include NASA, military, and commercial satellites, as well as the proposed Lunar Gateway. The 3D printed LHPs and PCM thermal storage modules are applicable to both Lunar/Martian and Microgravity thermal control systems. The Warm-Reservoir VCHPs are more applicable to Lunar/Martian systems, since they help minimize power requirements during the Lunar and Martian nights.

Benefits: The immediate NASA application is thermal control of Lunar Landers and Rovers, providing variable thermal links that passively shut down during the Lunar night, or in a shadowed crater. The proposed program will design and fabricate engineering test units for the NASA VIPER rover. Once validated, these architectures can be used on future Landers, Rovers, and for Manned Missions, e.g., in the HEOMD Lunar CATALYST project/SAA under Lander Technologies. Potential NASA applications in microgravity are discussed below.

Conventional LHPs are a mainstay of spacecraft thermal control for commercial communications, NASA, and military satellites. However, they cost more than most CubeSats. The 3D printed LHP reduces costs by an order of magnitude, allowing them to be used in CubeSats. CubeSats that dissipate energy at a high rate require PCM thermal storage to temporarily store the heat before it is radiated.