Lunar Regolith Evolution From Thermal Conductivity: A New Maturity Indicator

Abstract

Building upon an original data set that couples particle‐scale voxel features with the intrinsic thermal properties of lunar regolith particles, this study establishes a framework for predict thermal conductivity under multi‐scale parameter constraints. Within a Gaussian process regression framework, physically constrained kernel functions explicitly distinguish the different roles of temperature and microstructural factors in heat conduction, enabling reliable prediction of the intrinsic thermal conductivity of individual lunar regolith particles. The particle‐scale predictions are subsequently incorporated, together with the sample‐based measurements of average macroscopic packing characteristics, into a parameterized thermal‐resistance network model to quantitatively characterize the equivalent macroscopic thermal conductivity of the lunar surface regolith under different geological settings. Furthermore, the systematic variation of thermal conductivity with regolith weathering maturity is analyzed, and a method for assessing lunar regolith maturity based on the relative magnitude of macroscopic thermal conductivity is proposed. Based on the thermal resistance network model, a calculated equivalent macroscopic thermal conductivity, , greater than 1.20 × 10 ⁻³  W m ⁻¹  K ⁻¹ suggests relatively immature regolith, whereas below 0.60 × 10 ⁻³  W m ⁻¹  K ⁻¹ may indicate a highly mature state. Comparisons with thermal conductivity derived from remote‐sensing inversions and with magnetic‐resonance‐based maturity measurements provide support for the feasibility of the proposed approach as a complementary indicator for characterizing lunar regolith maturity. The results further suggest that the regolith at the Chang'e‐5 landing site is likely immature, while the Chang'e‐6 landing site exhibits a higher degree of maturity relative to Chang'e‐5.