Retrieval Of Lunar Heat Flow And The Density Of Lunar Regolith Based On Remote Sensing Data

Lunar heat flow and the density of lunar regolith are of vital important to understand the origin and evolution of the Earth-Moon system and solar system.The radiation brightness temperature obtained from microwave radiometers on Chang’E-1and Chang’E-2satellites is the comprehensive embodiment of lunar surface layer temperature, heat flow, density and so on. Retrieval of lunar heat flow and density by microwave brightness temperature is the first in the world. The main research work is shown as follows:Lunar surface layer temperature is the main factor affecting the microwave brightness temperature. Based on a one-dimension thermal conduction equation, lunar surface layer temperature varying with time, depth and geographic position are investigated. The calculated lunar surface temperature is compared with that obtained by the Diviner on Lunar Reconnaissance Orbiter. According to the difference between the calculated and measured results, the calculated temperature varying with time is improved by adjusting the thermal parameters.Lunar heat flow is a key parameter for studying the thermal state and thermal evolution of the Moon. Retrieval of lunar heat flow within75to65(?), and60(?) to100(?) region from microwave brightness temperature measured by Chang’E-2Lunar Microwave Radiometer and infrared brightness temperature measured by Lunar Reconnaissance Orbiter Diviner Radiometers is presented. The lunar heat flow is obtained as the product of the vertical temperature gradient and the thermal conductivity in the regolith. The vertical temperature gradient is calculated by a new temperature profile, the unknown parameters of which are determined from CE-2microwave brightness temperature using a multi-layered lunar surface brightness temperature model. The boundary condition of the temperature profile is determined by LRO infrared brightness temperature. The retrieved lunar heat flow within75(?) to65(?), and60(?) to100(?) region, is ranged from0.8to69.2mW/m2.Lunar heat flow could not only be obtained by microwave brightness temperature, but also by the souces which cause the heat flow. Based on radioactive elements K, U and Th, We construct a model of lunar heat flow which includes the heat flow from the non-uniform distribution of radioactive elements K, U and Th and that from secular cooling of the Moon. Correlation analysis of the three radioactive elements is carried out due to the higher resolution of Th abundance and for ease of calculation. The radioactive elements are derived from calibrated Lunar Prospector gamma-ray spectrometer data. It shows that heat flow varies regionally from about10.6mW/m2to66.1mW/m2, which is near the result from retrieval based on microwave brightness temperature.Analysis of the diurnal difference of microwave brightness temperature observed by Chang’E-1and Chang’E-2satellites is carried out for (30°N,25°N) in Mare Imbrium and (30°N,55°N) in Oceanus Procellarum of uniform infrared brightness temperature and FeO+TiO2content. It can be concluded that distinct diurnal differences of microwave TB in both these regions are related to bulk density of lunar subsurface layer. Based on two-layered lunar surface brightness temperature model, retrieval of the bulk density of lunar subsurface layer is presented. The bulk density of the subsurface layer is retrieved from microwave brightness temperature observed by Chang’E-2, ranging from1.90to2.04g/cm3within33°N, and120°W to6°E region.