Quantitative Analysis of Subsurface Dielectric Properties by Chang’E-4 Lunar Penetrating Radar Over Lunar Days 24–31

Lunar volcanic activity and its impact on near-surface material composition are central to lunar geological research. As of March 2024, the Yutu-2 rover has been operational on the Moon for 65 lunar days, covering a total distance of 1617.28 m. Radar data collected by the rover during the 24th to 31st lunar days, spanning approximately 120 m, clear horizontal reflection echoes. These reflections can be exploited for the estimation of the dielectric properties of the stratified structures. In this study, the finite-difference time-domain (FDTD) method is applied to quantitatively assess the positions and the electromagnetic properties of subsurface layers within the shallow subsurface (approximately 40 m in depth) as detected by Yutu-2. Therefore, the article deals with the first quantitative analysis of the positions and dielectric characteristics of four stratified layers beneath the Chang’E-4 (CE-4) landing site. Based on the results, the lunar layered near-surface structure is redefined in terms of a homogeneous regolith layer, an ejecta layer, a basalt layer, and a lightly weathered regolith layer. Furthermore, this study offers a detailed interpretation of the shallow geological structure at the CE-4 landing site, providing potential evidence of recent volcanic activity in the region.