Investigation of the Thermal Conductivity of Dry and Icy Lunar Regolith Simulants

This study investigates the thermal conductivity of lunar regolith simulants, both with and without the addition of ice. A novel icy regolith simulant was developed, combining microgranular water ice particles and lunar highlands simulant LHS-1. Thermal conductivity measurements were conducted in a thermal vacuum chamber over a temperature range of 100–450 K using the transient hot strip method. The results for dry regolith simulants align with the small magnitude and temperature dependence observed in Apollo samples. Icy simulants with low ice content (10 wt%) exhibited similarly low thermal conductivity at low temperatures, with minimal variation due to ice content. However, sublimation caused significant changes with increasing temperature, highlighting the influence of latent heat transport. Sublimation also induced cementation, suggesting that lunar ice deposits may have developed sintered outer layers. Interconnected icy regolith simulants displayed slightly higher thermal conductivity, even at low ice content. This work provides insights into the thermal properties of possible forms of icy and dry lunar regolith, particularly for ice-bearing regions near the lunar south pole. These findings support the development of thermophysical models and resource extraction experiments for permanently shadowed regions.