The Volatiles Investigating Polar Exploration Rover (VIPER) Thermal Management System (TMS) is a critical part of the vehicle's thermal subsystem that ensures rover electrical components are maintained within operational and survival limits. NASA performed a trade study in 2019 for various technologies to define the VIPER TMS concept. The Loop Heat Pipe (LHP) with Thermal Control Valve (TCV), was selected in 2021 as the main transport component for flight after completion of the Thermal Vacuum (TVAC) testing for initial study. This initial study also defined the warm-box design as honeycomb panels with embedded constant conduction heat pipes. These early efforts defined the final VIPER TMS and the requirements needed in SBIR contracts to ACT for flight hardware. The VIPER TMS concept was designed to meet challenging thermal requirements, which included extended operations in Permanently Shadowed Regions (PSRs) and extended lunar darkness survival. The VIPER TMS intended to minimize heat loss during lunar darkness to optimize power consumption, and to maximize heat rejection during maximum thermal loading. The components under contract included a warm-box, for the temperature sensitive electronics to reside, the thermal transport design four Loop Heat Pipes, and the radiator panel assembly with Z93C55 white coating. Additionally, axial grooved constant conductance heat pipes are used to thermally couple each side of the warm-box, and to couple the MSOLO and NIRVSS science instruments, located outside of the warm-box, to the warm-box environment. One of the key innovations was to incorporate passively activated Thermal Control Valves (TCV) into the LHPs to reduce heat loss during lunar darkness operations. This NASA and ACT collaboration resulted in the successful final design, manufacturing and delivery of the TMS flight components to Johnson Space Center for vehicle integration. This publication captures the work performed to meet the thermal requirements and the component level testing performed.
Smay et al. (Sun,) studied this question.