Artemis 3 Lunar Environment Monitoring Station (LEMS-A3) Thermal Control Subsystem Architecture

The NASA Artemis 3 Lunar Environment Monitoring Station (LEMS-A3) instrument will be deployed by the Artemis 3 crew in the South Pole region of the Moon. LEMS-A3 consists of a common services bus and two seismometers to be buried in the regolith, and the instrument has been repackaged to improve the performance of the bus Thermal Control Subsystem (TCS). The nighttime heat leak has been reduced from 3W to 1.2W, from Engineering Design Unit (EDU) Thermal Vacuum (TVAC as predicted for the LEMS-A3 Critical Design Review (CDR). This improvement was brought about by repackaging that reduces surface area for the Integrated Multi Layer Insulation (IMLI), optimizing harness passthroughs including the selection of cryogenic coaxial cables, selecting an improved differential thermal expansion heat switch, and redesign of the Launch Lock (LL). The upgraded configuration enables LEMS-A3 to continuously operate in and survive the lunar night for up to 24 lunations to meet extended-operation mission objectives. This paper discusses the repackaging, thermal design improvements, and upgraded thermal hardware. Also, requirements for subsurface thermal analysis of the seismometer instrument in the Lunar South Pole region are presented. These include assumed worst case hot and cold biasing of regolith and seismometer properties for both astronaut deployment and nominal subsurface operations.