Subsoil structure at the Chang’E-6 landing site revealed by in-situ Lunar Regolith Penetrating Radar

As humanity's first sample return mission from the lunar farside, China's Chang'E-6 mission provides a unique window into understanding the dichotomy in lunar nearside-farside evolution. Chang'E-6 landed in the southwestern Apollo basin (~2.79 Ga) within the South Pole–Aitken basin, providing a valuable record of early solar system impacts. Equipped with a Multi-Input-Multi-Output Lunar Regolith Penetrating Radar, the mission enabled the first detailed investigation of the shallow subsurface structure at the farside. By employing a tailored data processing approach, we obtained high-resolution subsurface images and revealed a distinct two-layer structure to a depth of 3 m. The upper layer (~1.7 m thick) consists of fine-grained, highly weathered regolith, while the lower layer (extending to 3 m) contains coarse, unweathered ejecta. Furthermore, by integrating data from Apollo and Chang'E missions, we identified a potential relationship between the lunar surface geological age and the shallow regolith's electromagnetic losses. Specifically, geologically older regions exhibit lower electromagnetic attenuation, suggesting a possible link between regolith maturity and electromagnetic properties. These findings provide critical insights into the geological evolution of the Moon, and also offer unprecedented opportunities for correlating in-situ radar measurements with laboratory analyses of the farside samples, fundamentally advancing our understanding of lunar exploration. An analysis of subsoil structure using lunar regolith penetrating radar at the Chang'E-6 landing site indicates a distinct 2-layer structure, and when compared with Apollo mission data, suggests a link between regolith maturity and electromagnetic properties.