Global Regolith Thermophysical Properties of the Moon From the Diviner Lunar Radiometer Experiment

We used infrared data from the Lunar Reconnaissance Orbiter (LRO) Diviner Lunar Radiometer Experiment to globally map thermophysical properties of the Moon's regolith fines layer. Thermal conductivity varies from 7.4 × 10−4 W m−1 K−1 at the surface to 3.4 × 10−3 W m−1 K−1 at depths of ~1 m, given density values of 1,100 kg m−3 at the surface to 1,800 kg m−3 at 1 m depth. On average, the scale height of these profiles is ~7 cm, corresponding to a thermal inertia of 55 ± 2 J m−2 K−1 s−1/2 at 273 K, relevant to the diurnally active near‐surface layer, ~4–7 cm. The temperature dependence of thermal conductivity and heat capacity leads to an ~2 times diurnal variation in thermal inertia at the equator. On global scales, the regolith fines are remarkably uniform, implying rapid homogenization by impact gardening of this layer on timescales