Rock Location and Quantitative Analysis of Regolith at the Chang’e 3 Landing Site Based on Local Similarity Constraint

Bin Hu,Zhaofa Zeng,Ling Zhang,Deli Wang

doi:10.3390/rs11050530

Abstract

Structural analysis of lunar regolith not only provides important information about lunar geology but also provides a reference for future lunar sample return missions. The Lunar Penetrating Radar (LPR) onboard China’s Chang’E-3 (CE-3) provides a unique opportunity for mapping the subsurface structure and the near-surface stratigraphic structure of the regolith. The problem of rock positioning and regolith-basement interface highlighting is meaningful. In this paper, we propose an adaptive rock extraction method based on local similarity constraints to achieve the rock location and quantitative analysis for regolith. Firstly, a processing pipeline is designed to image the LPR CH-2 A and B data. Secondly, we adopt an f-x EMD (empirical mode decomposition)-based dip filter to extract low-wavenumber components in the two data. Then, we calculate the local similarity spectrum between the filtered CH-2 A and B. After a soft threshold function, we pick the local maximums in the spectrum as the location of each rock. Finally, according to the extracted result, on the one hand, the depth of regolith is obtained, and on the other hand, the distribution information of the rocks in regolith, which changes with the path and the depth, is also revealed.

Highlights

Chang’E-3 landed at 340.4875 ◦E, 44.1189 ◦N on the Moon on 14 December 2013 in a new region that has not been explored before in the largest basin—the Mare Imbrium [1]
We propose an adaptive rock extraction method based on local similarity constrains to achieve the rock location and quantitative analysis for regolith
According to the extracted result, on the one hand, the depth of regolith is obtained, and on the other hand, the distribution information of the rocks in regolith, which changes with the path and the depth, is revealed

Summary

Introduction

Chang’E-3 landed at 340.4875 ◦E, 44.1189 ◦N on the Moon on 14 December 2013 in a new region that has not been explored before in the largest basin—the Mare Imbrium [1]. The dual-frequency Lunar Penetrating Radar aboard the Yutu Rover provides a unique opportunity to map the subsurface structure to a depth of several hundreds of metres from the low-frequency channel (CH-1, 60 MHz) and the near-surface stratigraphic structure of the regolith from the high-frequency channel (CH-2A &CH-2B, 500 MHz). LPR data processing and initial results were first presented by NAOC [3]. Initial analysis of the LPR observations, especially that from the CH-1, indicates that there are more than nine subsurface layers from the surface to a depth of ~360 m [1]. The onboard Lunar Penetrating Radar conducted a 114-m-long profile, which measured a thickness of ~5 m of the lunar regolith layer and detected three underlying basalt units at depths of 195, 215, and 345 m. Dong et al and Zhang et al calculated the parameters of the regolith [8,9]

Methods

Results

Discussion

Conclusion