Self-Organization Characteristics of Lunar Regolith Inferred by Yutu-2 Lunar Penetrating Radar

Xiang Zhang,Wenmin Lv,Yangting Lin,Zhenxing Yao,Jinhai Zhang,Lei Zhang

doi:10.3390/rs13153017

Abstract

Most previous studies tend to simplify the lunar regolith as a homogeneous medium. However, the lunar regolith is not completely homogeneous, because there are weak reflections from the lunar regolith layer. In this study, we examined the weak heterogeneity of the lunar regolith layer using a self-organization model by matching the reflection pattern of both the lunar regolith layer and the top of the ejecta layer. After a series of numerical experiments, synthetic results show great consistency with the observed Chang’E-4 lunar penetrating radar data and provide some constraints on the range of controlling parameters of the exponential self-organization model. The root mean square permittivity perturbation is estimated to be about 3% and the correlation distance is about 5–10 cm. Additionally, the upper layer of ejecta has about 1–2 rocks per square meter, and the rock diameter is about 20–30 cm. These parameters are helpful for further study of structural characteristics and the evolution process of the lunar regolith. The relatively small correlation distance and root mean square perturbation in the regolith indicate that the regolith is mature. The weak reflections within the regolith are more likely to be due to structural changes rather than material composition changes.

Highlights

The structure of the lunar shallow surface is complex due to long-term impacting, sputtering and stacking processes; in addition, the Moon has no strong cementation due to the absence of interstitial water
We used three self-organization random models with different autocorrelation functions to simulate the lunar regolith on the far side of the Moon
Through a series of comparative analyses of the simulated and observed lunar penetrating radar (LPR) data, we found that the structure of the lunar regolith in the landing area of Chang’E-4 can be expressed by an exponential autocorrelation random model

Summary

Introduction

The structure of the lunar shallow surface is complex due to long-term impacting, sputtering and stacking processes; in addition, the Moon has no strong cementation due to the absence of interstitial water. The remote-sensing spectrum and radar detection results show that there is a thick regolith layer on the top of the. Von Kármán crater [1,2,3]. This provides an excellent opportunity for detection of the structural characteristics and the stacking mode of the lunar regolith, which are critical for understanding the formation process of the lunar regolith. In the past, the lunar regolith has usually been assumed to be a uniform layered medium [4,5,6,7,8]. A series of recent studies have shown that the lunar regolith is essentially inhomogeneous [9,10,11,12,13,14,15,16] but the specific structural characteristics of the lunar regolith are still unclear

Results

Discussion

Conclusion