TY - JOUR
T1 - Rock Fragments in Shallow Lunar Regolith
T2 - Constraints by the Lunar Penetrating Radar Onboard the Chang'E-4 Mission
AU - Ding, Chunyu
AU - Xiao, Zhiyong
AU - Wu, Bo
AU - Li, Zhaojin
AU - Su, Yan
AU - Zhou, Bin
AU - Liu, Kaijun
AU - Cui, Jun
N1 - Funding Information:
The Chang'E‐4 mission was carried out by the Chinese Lunar Exploration Program, and the scientific data are provided by the China National Space Administration. Comments and suggestions provided by Dr. Sarah Kruse and an anonymous reviewer helped clarifying and improving the manuscript. The authors are supported by the B‐type Strategic Priority Program of the Chinese Academy of Sciences (grant XDB41000000), the National Natural Science Foundation of China (42004099 and 41773063), the SUSTech Presidential Postdoctoral Fellowship, the Opening Fund of the Key Laboratory of Lunar and Deep Space Exploration (No. LDSE202005) and the Key Research Program of Frontier Sciences of Chinese Academy of Sciences (No. QYZDY‐SSW‐DQC028), the pre‐research Project on Civil Aerospace Technologies (D020201 and D020202) funded by the Chinese National Space Administration, a grant from the Research Grants Council of Hong Kong (Research Impact Fund—Project No: R5043‐19), and Shenzhen Municipal Government Investment Project (No. 2106‐440300‐04‐03‐901272).
Publisher Copyright:
© 2021. American Geophysical Union. All Rights Reserved.
PY - 2021/9
Y1 - 2021/9
N2 - It is generally believed that the top centimeters of mature lunar regolith should be dominated by fine particles that contain few rocky fragments, but surface fragments are occasionally visible in mature lunar regolith. Based on amplitudes of surface echoes received by the Lunar Penetrating Radar onboard the Yutu-2 rover of the Chang'E-4 mission, we extracted regions with abnormally high relative permittivity that is larger than 4, quantifying the abundance of dense fragments within the top ∼4 cm of the mature regolith along the rover path. We carried out high-resolution numerical simulations for the propagation of electromagnetic waves, showing that the abnormally high relative permittivity is not caused by local topography but due to the existence of dense materials. Using high-resolution images obtained by the panorama camera onboard the rover, we performed correlated observation for areas with abnormally high relative permittivity, confirming that some of these dense materials are exposed rocky fragments. However, most of the high relative permittivity areas are not correlated with surface fragments, and some are located beneath floors of highly degraded small impact craters. We found that regolith clumps formed due to impact compaction are not dense enough to cause the abnormally large relative permittivity. Alternatively, the detected dense materials may be melt-bearing impact breccias in the shallow regolith, which were formed by the host craters. The results revealed a highly heterogeneous structure at shallow depths of mature lunar regolith, revealing a new mechanism of sand-blasting impacts on the destruction of pores in mature lunar regolith.
AB - It is generally believed that the top centimeters of mature lunar regolith should be dominated by fine particles that contain few rocky fragments, but surface fragments are occasionally visible in mature lunar regolith. Based on amplitudes of surface echoes received by the Lunar Penetrating Radar onboard the Yutu-2 rover of the Chang'E-4 mission, we extracted regions with abnormally high relative permittivity that is larger than 4, quantifying the abundance of dense fragments within the top ∼4 cm of the mature regolith along the rover path. We carried out high-resolution numerical simulations for the propagation of electromagnetic waves, showing that the abnormally high relative permittivity is not caused by local topography but due to the existence of dense materials. Using high-resolution images obtained by the panorama camera onboard the rover, we performed correlated observation for areas with abnormally high relative permittivity, confirming that some of these dense materials are exposed rocky fragments. However, most of the high relative permittivity areas are not correlated with surface fragments, and some are located beneath floors of highly degraded small impact craters. We found that regolith clumps formed due to impact compaction are not dense enough to cause the abnormally large relative permittivity. Alternatively, the detected dense materials may be melt-bearing impact breccias in the shallow regolith, which were formed by the host craters. The results revealed a highly heterogeneous structure at shallow depths of mature lunar regolith, revealing a new mechanism of sand-blasting impacts on the destruction of pores in mature lunar regolith.
KW - Chang'E-4
KW - impact craters
KW - lunar penetrating radar
KW - Moon
KW - regolith
KW - relative permittivity
UR - http://www.scopus.com/inward/record.url?scp=85115747683&partnerID=8YFLogxK
U2 - 10.1029/2021JE006917
DO - 10.1029/2021JE006917
M3 - Journal article
AN - SCOPUS:85115747683
SN - 2169-9097
VL - 126
JO - Journal of Geophysical Research: Planets
JF - Journal of Geophysical Research: Planets
IS - 9
M1 - e2021JE006917
ER -