Inversion of lunar regolith thickness by microwave brightness temperature

The purpose of this paper is to establish a more suitable method to investigate the lunar regolith depth from microwave radiation brightness temperature data of the lunar surface. The physical properties of the lunar surface influencing on the brightness temperature are comprehensively discussed. An approximate determination of the lunar subsurface temperature distributation function is proposed on the basis of previous researches. Considering the variation of these influence factors, a new multi-layer microwave radioactive transfer model is presented to inverse the thickness of lunar regolith. By applying fluctuation dissipation theorem, microwave radiation brightness temperature of the lunar regolith based on this multi-layer model is theoretically deduced and the brightness temperatures of the lunar regolith obtained from Chang'E-1 satellite are simulated on the basis of aforementioned works. An approximate function of inversion is presented. Taking these simulation results with random noise as observation data, an inversion method of the lunar regolith-layer thickness is developed. The error analysis shows that this method is more reasonable than that based on "three-layer model".