Inversion Of Composition And Analysis Of Structure In The Lunar Subsurface From Chang’E Microwave Data

Remote sensing technique has been applied into lunar exploration currently, suchas visible, infrared. However, the penetration depths limit the use of remote sensingtechnique and only reflect the surface information of the moon, which disables thetechniques above to explore resource inside lunar regolith layer and reflect thesubsurface structure of lunar regolith. There is no existence of water in lunar surface,and electromagnetic waves could observe the surface and subsurface of the lunarregolith that has low dielectric loss. Therefore, how to apply microwave technique ofthe earth to lunar exploration is an important task.Based on microwave radiometerdata and Lunar Penetrating Radar on Chang’E-1lunar satellite, this paper this paperalso explore the features and composition of lunar surface regolith and layeredstructure of shallow lunar crust by considering electromagnetic scattering andradiation as physical basis, microwave remote sensing as technical method, whichaims to solve the basic problems of applying microwave technique to observingthe lunar surface and provides the theory basis for future Moon probe program.First, the microwave radiometer and lunar penetrating radar data are processed inthe research, during which several correction methods of hour angle has been used tomicrowave radiometer. The correlation between hour angle and brightnesstemperature (TB) has been studied under different frequency and latitude, and thendaily change model of TB under different frequency and latitude has been built up,which carries out the hour angle correction on TB and obtains the microwave TBdistribution for the whole moon for specified time. The TB distributions for the wholemoon in different time and under different frequency are also obtained by Krigingmethod. Based on DEM data and CCD image data, the microwave TB has beenvalidated and the results show that the TB mapping of the whole moon applying hourangle correction to microwave radiometer could express the moon topography andreflectance of moon surface very well. The processing of radar data mainly includes:three radar survey lines are determined by the relative position of moon probe radar,and the bad tracts of radar data has been excluded and image mosaic of radar data hasbeen carried out and the oscillograph of reflectance wave of radar are finally obtained under two channels60MHz and500MHzThe brightness temperature mapping of the whole moon under12different timeand frequency has been analyzed combing SVD model and the TB correlation map oflunar surface are obtained. The relationship between TB abnormal variations andvolcano distribution in middle and low latitude area; and the permanently shadowedregions of moon are extracted from DEM data, and possible position of lunarwater-ice is discussed.Based on radiative transfer model and TB data of the whole moon, the real andimaginary part of dielectric constant for the whole moon under3GHz are inversedpreliminarily through calculating the relative parameters. The dielectric constant oflunar mare is higher than that of lunar terrace; the real part of dielectric constant is onthe low side in polar area, and the imaginary part is relatively high in lunar mare andAitken basin. The temperature correction of inversion result is carried out throughsimulation experiment on dielectric constant of lunar surface, and dielectric constantof the whole moon at22°C is obtained. The inversion result compares with themeasured dielectric constant of real lunar soil sample, and the results show therelative error of real part is less than11%and that of imaginary part has higherrelative error, but the maximum difference is only0.02.The functional relation between the imaginary part of dielectric constant andFeO+TiO2has been studied, and quantitative retrieval of FeO+TiO2for the wholemoon has been carried out. The FeO+TiO2has rather high percentage of20-30%inlunar mare and Aitken basin while FeO+TiO2is relatively low in plateau area.Comparing inversion result from v-ray, Clementine result and MRM data on CE-2with experiment data from real lunar soil respectively, MRM data has the highestcorrelation coefficients with measurement result of real lunar soil.To explain the observation of moon probe radar, the observation of differentgeologic structure are simulated by GprMax and the wave features of radarreflectance wave is also analyzed, including layered simulation of lunar surfacestructure, water-ice distribution simulation inside the lunar soil and undersidesimulation of lunar rock. Besides computer simulation of radar data, the simulation experiment of lunarsurface has been carried out, which takes Dove Mountain in Xilinhaote of InnerMongolia as test site where the geological structure is similar to moon. Theexperiment used ground penetrating radar simulated the observation of60MHz moonprobe radar over shallow structure of lunar surface, and correlation analysis is carriedout on geological situation by ground penetrating radar. Meanwhile laboratoryexperiment to simulate moon probe is carried out. A short profile is designed inlaboratory experiment, the simulation is carried out on moon probe radar by theobservation depths of500MHZ moon probe radar. Finally, data processing of radar isused to moon probe radar, which mainly covers data filter, data mosaic, deconvolutionand compensated diffusion. Combining processing result with GPRMax and surfacesimulation, the thickness of lunar soil and shallow structure of lunar surface.