Thermal Diffusivities and Specific Heats of Dry and Icy Lunar Regolith Simulants

Abstract

The development of thermal methods for the extraction of water from icy regolith in the polar regions of the Moon requires a knowledge of its thermophysical properties, which is currently insufficient. In the present paper, the specific heats and thermal diffusivities of lunar regolith simulants LHS-1 and LHS-1D were studied at low temperatures, using differential scanning calorimetry and laser flash analysis. The specific heats of dry simulants have been measured in the temperature range of 110−320 K. The obtained values are close to the specific heats of the Apollo regolith samples at the same temperatures. The thermal diffusivities of dry simulants have been measured in the temperature range of 148−300 K in a helium environment at about 90 kPa and in vacuum (< 1 Pa). The values are significantly smaller in vacuum. The thermal diffusivity decreases with increasing temperature and decreasing particle size. The specific heats of LHS-1 and LHS-1D, mixed with water, have been measured in the temperature range of 110−340 K. The increase in specific heat due to the addition of 3−5 wt% ice was within the experimental error.