Microwave transfer models and brightness temperature simulations of MWS for remote sensing lunar surface on CE-1 satellite

Abstract

China has launched a microwave radiometer (MWS) to the Moon orbit to detect regolith information of the lunar surface. It is the first time that humankind directly applies sensed brightness temperature to investigate the lunar surface information by passive microwave sensor on lunar orbit. Therefore, it is necessary to set up theoretical models to describe lunar surface microwave transfer process, as well as heat conduction. These models will finally used for retrieving lunar surface information on regolith depths. In this paper, we will derive a microwave radiative transfer model for simulating MWS brightness temperature. We solve numerically the integral equation of the lunar soil by dividing the soil into many layers, and at each layer, emission, multi-reflection, and attenuation to the sub-layer radiation are all summed into a formula. The contributions of the underlying rock are also included for evaluating the amount of brightness temperature due to soil depth variation. Because it is necessary to learn about temperature distribution of lunar near surface layers for brightness temperature simulation, we simulate all the profiles from surface to 6 m depth of lunar surface from the North polar to the Equator of lunar using heat conduction equation with latest models of density, specific heat, and heat conductivity of lunar regolith. Finally, Some simulated brightness temperatures at different location of lunar surface are given by our models, which will be validated by MWS measurements soon.