The Chang’E-6 Landing Region: Geologic Context, Mare Basalt, and Regolith Properties

Chang’E-6 (CE-6) is the first lunar farside sample-return mission. It landed in an Eratosthenian mare basalt unit within the South Pole-Aitken basin (SPA) and returned 1,935.3 g samples. These returned samples can address a wide range of fundamental questions about the Moon, including the nature of farside volcanism and mantle, the stratigraphy and evolution of the SPA terrain, the impact flux, chronology, and space weathering process of the lunar farside. This study investigates the geological context, mare basalt, and regolith properties of the CE-6 landing region using multi-source remote sensing observations. The size and spatial distributions of the penetrating craters and buried craters reveal that the thickness of the surface Eratosthenian basalt in most regions ranges from $\sim$30–60 m, and a layer of Imbrian basalts with a thickness of $\sim$90–120 m lies beneath. Morphology and rock population of small fresh craters within a 3 km radius of the landing site indicate a 2–10 m thick regolith layer with a median thickness of $\sim$3 m. Combined analysis of infrared and radar observations suggests a finer regolith at the landing site, with fewer meter-scale rocks but more centimeter- to decimeter-scale rocks compared with Chang’E-5 landing site. The surface features in the mare unit suggest that the regolith at the landing site may contain exotic ejecta primarily from Chaffee S, Vavilov, Lovell, and White craters, potentially including SPA melt and mantle materials. These findings improve the understanding of volcanic activity and regolith evolution at the landing site, and further provide foundations for subsequent laboratory analysis of the returned samples.