Challenges of Designing a Passive Thermal Control System for the Astrobotic Peregrine Lunar Lander

The Astrobotic Peregrine is a lunar lander currently undergoing design by Astrobotic Technology with help from NASA through the Lunar Cargo Transportation and Landing by Soft Touchdown (Lunar CATALYST) program. This paper will discuss the challenges of designing a passive thermal control system for the lander, and how the design has evolved from the initial passive concept. These challenges include drastically varying worst hot and worst cold case thermal environments, narrow temperature limits of critical components, limited available locations for spacecraft component mounting, and unexpected changes causing significant thermal impacts. The initial thermal control strategy was to cold bias the spacecraft by thermally coupling all spacecraft components to one mounting deck, which also doubled as a radiator, and using heaters to maintain each component’s temperature above its lower temperature limit when in the cold environments. As the design evolved, this strategy alone became inadequate. As heat dissipations increased and became more varying with the addition of components, the thermal design was changed and additional thermal control technologies added. Thermal control strategies incorporated into the design include dictating the lander orientation in demanding environments, defining locations for critical spacecraft components, limiting component operation when possible, and using technology to create variable thermal contacts. Additional design changes will occur as the design continues to evolve to optimize the most effective thermal control system. The thermal design of Peregrine is still in progress, with Critical Design Review (CDR) scheduled for December 2019.