Ejecta Fragment Transport Across the Moon: Implications for Lunar Sample Provenance

Abstract Impact cratering redistributes geologic materials on up to global scales. On the Moon, cratering events contribute to the mixing of maria and the highlands. To better understand the role of impact ejecta in the redistribution of materials, we developed an analytical method to estimate the largest ejecta fragment sizes that could have been delivered to previous sample collection sites from selected primary impacts into lunar maria targets across the Moon. The ejecta fragments would not remain intact upon impact but would form secondary craters and be further eroded and mixed into the regolith. Here, we use maximum ejecta sizes as a proxy for the relative possible contributions of each assessed primary crater. All of the 45 primaries considered here (0.83–138 km in diameter) could potentially contribute sizable maria fragments to each landing site. The larger (>65 km diameter) and closer (<2,000 km distance) primaries resulted in the largest estimated fragment sizes (∼0.5–2.5 km), whereas the smaller (<65 km) and more distant (>2,000 km) primaries resulted in the smallest fragment sizes (up to ∼250 m). Depending on spatial proximity, both smaller and closer and larger and more distant primaries could also deliver relatively large (∼0.2–0.8 km) ejecta fragments. Our results provide context to understand how maria material may have become incorporated into distant surfaces and lunar sample locations.