Deriving historical total solar irradiance from lunar borehole temperatures

Abstract

We study the feasibility of deriving historical TSI (Total Solar Irradiance) from lunar borehole temperatures. As the Moon lacks Earth's dynamic features, lunar borehole temperatures are primarily driven by solar forcing. Using Apollo observed lunar regolith properties, we computed present‐day lunar regolith temperature profiles for lunar tropical, mid‐latitude, and polar regions for two scenarios of solar forcing reconstructed by Lean (2000) and Wang et al. (2005). Results show that these scenarios can be distinguished by small but potentially detectable differences in temperature, on the order of 0.01 K and larger depending on latitude, within ∼10 m depth of the Moon's surface. Our results provide a physical basis and guidelines for reconstructing historical TSI from data obtainable in future lunar exploration.