Modeling Rover Interactions with Lunar Regolith in Permanently Shadowed Regions

Blueshift, LLC doing business as Outward Technologies proposes to develop a coupled Discrete Element Method (DEM) and Finite Element Method (FEM) modeling framework using open-source software to simulate the combined thermal and mechanical interactions between rovers and regolith in and around Permanently Shadowed Regions (PSRs) on the Moon. This proposed set of numerical tools innovates on the current state of the art by simulating the thermomechanical response of lunar soil containing volatiles and by explicitly modeling volatile sublimation and advection through an ice-regolith mixture. A grain-based DEM model with user-defined soil compaction, grain shape, and particle size distributions will be coupled with FEM software to reduce computation time, enabling rover components including wheels, probes, and soil sampling equipment. This comprehensive modeling framework will be calibrated and validated through small-scale laboratory experiments for simulating bulk thermal conductivity, shear response, and penetration resistance of ice-regolith mixtures in cryogenic vacuum conditions. Sublimation will be evaluated in these experiments and models, as will deposition of water ice and formation of cemented icy-regolith. These combined numerical tools will enable NASA and its partners to inexpensively evaluate hardware designs for lunar ISRU missions aimed at exploration and prospecting for volatiles at the lunar poles. These improved modeling capabilities will further de-risk planned missions to the Moon by helping to identify successful control strategies and hardware designs for increased rover operability, ISRU sampling, material handling, and surviving the lunar night, thereby leading to more rugged and capable rovers for lunar polar missions while reducing their costs for development and testing.