Effective Medium Model Of Lunar Regolith And Its Application

Lunar regolith on the moon’s surface is rich in important mineral resources, suchas rare gas, ilmenite and He-3. It has a great significance on the lunar exploration andutilization of resources, that inverse dielectric constant to detect material compositionand structure of lunar regolith. Moreover, the parameters of lunar regolith areinfluenced by the exposure age and the age of impact craters, which posts a bigsignificance to the research on the impact of age and history development on themoon surface.Through analyzing the application of classical effective medium theoryMaxwell-Garnett as well as Bruggeman, two effective medium model of lunarregolith are established to study the relationship between lunar regolith dielectricconstant and its mineral composition as well as particle size of mineral.Four study areas are selected as sample spots to verify the accuracy of the modelin simulating the lunar regolith dielectric constant, including Hui-nan district of Jilinprovince, Wudalianchi and Jingbo lake of Heilongjiang province, Zhangjiakou inHebei and Inner Mongolia region. Volcanic rocks that have different lithofacies andoccurrence are collected as simulated samples. Using the vector network analyzer ofthe laboratory, the paper chooses coaxial probe method to measure the dielectricconstant of volcanic rock samples of200mesh, clinopyroxene and plagioclasepowder samples of80to200meshes and mixed minerals composed by monoclinicpyroxene and plagioclase in different volume fraction. Compare the value measuredby the test and the simulated value by the model, it is found that the measured value islarger than the simulated value based on the Maxwell-Garnett theory. The measuredvalue is smaller than that of Maxwell-Garnett theory considering the interactionbetween particles. And the measured and simulated values are close to each other byBruggeman theory. The variation trend between the dielectric constant and the mineralcomposition, the particle size of lunar regolith are then simulated. It is concluded thatlunar regolith dielectric constant increases as the particle size within the range of0~150μm, and remains stable within the range of150~1000μm. The contribution ofsoil minerals on equivalent dielectric constant are positively related to dielectricconstant and volume fraction with maximum dielectric constant respectively. There exits a negative correlation relationship between the value of lunar regolith and thevolume fraction of mineral with the minimum dielectric constant.The paper achieves the data processing work which includes data mosaic,removing the redundant data and digital filtering for the second channel data ofChang’e3lunar penetrating radar. On this basis, the double antenna delay method isused to inverse the average dielectric constant and thickness of lunar regolith layerunder the Chang’e3lunar rover patrol area. Finally, according to the rule simulatedby lunar regolith effective medium and the inversed dielectric constant, it is found thatthe content of ilmenite is within the range of0~11.52%, lunar regolith effectivemedium model peridot is within0~56.85%, clinopyroxene is within0~76.88%,plagioclase is not less than23.11%when the particle size is larger than150μm. Thesimulated content of mineral agrees with the real content of the Apollo and Lunasample, which offer a great help to the future lunar regolith resources exploitation.