Penetration based lunar regolith thermal conductivity inversion: Method and verification

Abstract

Based on the temperature change data of the penetrator, to achieve in-situ detection of the thermal conductivity of the lunar regolith profile, it is necessary to establish a heat conduction model between the penetrator and the lunar regolith. This study simplifies the heat conduction model of the complex shaped penetrator through simulation analysis results. Then, we proposed a thermal conductivity inversion method based on the transient thermal cylinder source model. The thermal diffusion test was carried out under normal temperature and pressure on a standard reference object with known thermal conductivity and the thermal conductivity inversion work was completed, which verified the feasibility of the inversion method. Then, we completed the thermal diffusion test of the penetrator and the lunar regolith simulant under the simulated low-temperature vacuum environment of the lunar surface, and carried out the thermal conductivity inversion of the lunar regolith simulant based on the thermal diffusion test data, which proved that the proposed thermal inversion method is applicable for the lunar regolith under the low-temperature vacuum. Finally, the thermal conductivity test was conducted on icy lunar regolith simulant with different water contents and a thermal diffusion test in a vacuum low-temperature environment was carried out. The thermal conductivity inversion was completed using the same method, which proved that the inversion method is suitable for icy lunar regolith simulant.