Impact Resurfacing of the Artemis Exploration Zone: Sample Locations for Primordial Crust and South Pole-Aitken (SPA) Ejecta

Regolith samples from the lunar south pole are expected to contain material from the ancient lunar crust and potentially the uppermost mantle, excavated by the South Pole-Aitken (SPA) impact. In this study, we aim to understand the impact resurfacing processes following the SPA impact and the subsequent redistribution of primordial crust and SPA-derived mantle material within the initial Artemis exploration zone (AEZ). Our goal is to identify optimal sampling locations for these materials. To achieve this, we reconstruct the south pole stratigraphy by modeling the cumulative thickness of post-SPA crater materials and estimating the present SPA ejecta thickness. By calculating crater excavation depths, we then infer which craters were excavated from what stratigraphic layer. We estimate a cumulative post-SPA ejecta layer thickness of ∼190 m to ∼1.8 km across different locations. We infer that all craters >10 km in diameter within the AEZ have likely been excavated below the post-SPA regolith layer. Based on surficial presence of anorthositic and mafic material, we postulate an SPA ejecta thickness in the AEZ of several hundred meters up to ∼10 km. The extent to which primordial crust and SPA-derived mantle material have been excavated depends on the wide range of possible SPA ejecta thicknesses. Their surficial presence and sampling potential are influenced by the age of the excavating crater. By integrating the stratigraphic model with mineral maps, we identify promising sampling targets, including regolith with potentially concentrated SPA material in the ejecta blanket of Kocher and primordial crust in the ejecta blanket of Shackleton crater.