Non-Integrated Hot-Reservoir Variable Conductance Heat Pipe Tested on Peregrine Lander

As NASA prepares to further expand human and robotic presence in space, it is well known that spacecraft architecture will be impacted by unprecedented power requirements and extreme thermal environments. In these conditions, thermal management systems need to reject large heat loads into hot environments and have high heat rejection turn-down ratios to minimize vehicle power needs during periods of cold darkness, such as the 14-day lunar night. Variable conductance heat pipes (VCHP) are capable of passively transporting large quantities of heat and provide high thermal turndown ratios that are ideal for surviving extremely cold environments. As shown in a previous paper [1] a non-integrated Hot Reservoir the VCHP was developed as flight hardware designed to fly onboard Astrobotic Technology’s lunar lander Peregrine and operate (as experimental hardware) both during transit and on the lunar surface utilizing a hybrid wick. The evaporator wick was 3D printed while the adiabatic and condenser sections utilized grooved wicks with high permeability optimum for operation in a microgravity environment. Three sets of tests were performed on this VCHP: testing on ground in ambient at ACT facilities (the results were presented at ICES 2022), pre-flight testing on ground in vacuum at NASA MSFC and testing during flight in microgravity on Peregrine Lander. In this paper, the development of the non-integrated HR-VCHP and the results obtained during the three sets of tests are discussed. All the successful evaluation, characterization and testing of the device both on ground and in space in microgravity led to its TRL increase to 8.