Moon’s subsurface heat flow mapping

This paper investigates the lunar subsurface heat flow using data from the recent Chinese lunar orbiting spacecrafts Chang’e 1 and 2 to explore variations in the subsurface temperature of the Moon. These variations include heat flow information of the subsurface and the interior of the Moon. This research aims to develop a radiative transfer forward model for an airless body and then utilize microwave radiometer (MRM) data to study an observed anomaly of elevated 2-m-deep TB measurements in the Oceanus Procellarum region on the lunar subsurface. After initial comparison of the data from MRM with that from instruments and modelling of the lunar regolith parameters, a multi-layer radiative transfer forward model has been derived using the fluctuation dissipation theorem. The forward model was then used to invert the MRM-measured TB data to generate temperature profiles of 2-m-deep subsurface. The provisional results show that, as expected, the temperature of 2-m subsurface is potentially correlated with the distribution of radioactive elements such as uranium and thorium in the lunar crust. The temperature map of 2-m subsurface was then converted to a lunar heat flow map, which was validated by the Apollo 15 and 17 measurements. Inspecting this heat flow map, abnormal high heat flow in the Oceanus Procellarum KREEP Terrain (PKT) region was noticed. The PKT is enriched with a high abundance of radioactive elements such as uranium and thorium. Hence, a heat flow model based on radioactive elements as well as internal cooling was built to investigate such a finding.