2022-06-172022-06-177/10/2022ICES-2022-035https://hdl.handle.net/2346/89588Jeff Diebold, Advanced Cooling Technologies, USCalin Tarau, Advanced Cooling Technologies, USJoshua Smay, Advanced Cooling Technologies, Inc., USTimothy Hahn, Advanced Cooling Technologies, Inc., USRyan Spangler, Advanced Cooling Technologies, Inc., USICES102: Thermal Control for Planetary and Small Body Surface MissionsThe 51st International Conference on Environmental Systems was held in Saint Paul, Minnesota, US, on 10 July 2022 through 14 July 2022.As NASA prepares to further expand human and robotic presence in space, it is well known that spacecraft architectures will be impacted by unprecedented power requirements and extreme thermal environments. Thermal management systems need to reject large heat loads into hot environments and have high heat rejection turn-down ratios in order to minimize vehicle power needs during periods of 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 turn-down ratios ideal for surviving extreme cold environments. In this paper, Advanced Cooling Technologies, Inc. (ACT) will discuss the design and testing of two unique non-integrated warm reservoir VCHPs. The first VCHP is flight hardware designed to fly onboard Astrobotic Technology�s lunar lander Peregrine. The Astrobotic VCHP is designed to operate during transit and on the lunar surface and utilizes a hybrid wick design. 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. The second VCHP was designed for NASA�s lunar rover VIPER. A unique feature of the VIPER VCHP was the flexible adiabatic section. In order to accommodate relative motion between the heat spreader panel and the radiator panel, due to launch induced vibrations, nested flexible lines for the VCHP envelope and internal non-condensable gas tube were used in the adiabatic section. Both VCHPs utilized a non-integrated warm reservoir of non-condensable gas. The non-integrated reservoirs provided high thermal turn-down ratios and the ability to independently heat the reservoir in order to purge working fluid increasing the reliability of the device.application/pdfengHeat pipesvariable conductance heat pipeshot reservoirthermal controlPresentation