Ejecta thickness and layering estimation for an example Artemis landing site candidate on the Moon

Abstract

We calculated the ejecta thickness and structural rim uplift at lunar craters larger than 0.45 km at the Artemis Connecting Ridge landing site. This analysis characterises the top few metres of the regolith, a layer that could be drilled by and come into physical contact with landers and rovers. Topographic profiles extracted from fresh craters were used to derive an empirical equation that describes the topography around craters, accounting for the structural rim uplift and back-fallen ejecta. Our results show a maximum cumulative ejecta thickness of 29.9 m at the landing site. This thickness is primarily derived from two craters: most originates from the largest crater (2.78 km in diameter), and a smaller portion comes from the second largest crater (0.86 km in diameter). The ejecta from the largest crater covers 72 km² with >1 cm thickness. Our models of stratigraphic sections reveal between 1 and 7 superposed ejecta layers across the region. The modelled regolith stratigraphy could be used to better target onsite activity and also interpret the results after measurements and sampling. Future work would incorporate ejecta from craters beyond the target area; here an example was only tested, which showed that the nearby Shackleton could provide up to 180 m thickness, but contributions from other distant craters are expected to be smaller in general.