Inversion of microwave brightness temperature data for estimating lunar regolith thickness

Abstract

The purpose of this paper is to establish a more suitable method for estimating 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. Considering the variation of these influence factors, an inhomogeneous multi-layer microwave radioactive transfer model is used to inverse the thickness of lunar regolith. By applying fluctuation dissipation theorem, the relationship between the microwave radiation brightness temperature of the lunar regolith and the thickness and temperature of lunar regolith based on this multi-layer model is theoretically deduced. 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. It indicates that the inverse ability of a certain frequency channel depends on the microwave penetration depth of this frequency channel. The thickness within the penetration depth can be accurately inversed. Using part of the brightness temperature data measured by the microwave radiometer on the Chang'e-1 satellite, the primary result of the lunar regolith thickness distribution is figured out.