Lunar grain size determination based on surface temperatures using ensembles of thermal model parameters

Abstract

Surface temperature measurements of airless bodies provide an opportunity to estimate regolith thermal properties via inverse modeling. However, thermal models involve many unknown parameters. Here an ensemble of thermal model calculations is applied to lunar nighttime surface temperatures in order to constrain the mean particle size of near-surface regolith materials. We find that many parameter combinations can produce the same surface temperatures, but a likely apparent grain size can be inferred without ad-hoc assumptions for other parameter values as long as grain size is among the leading causes for geographic variations in temperature.