Impact Gardening Affects the Composition of Chang'e-5 Lunar Soils

The composition of lunar samples sheds light on the Moon's evolutional history. Analyses of Chang'e-5 (CE-5) lunar soils showed <5% of foreign materials, significantly less than numerical predictions (∼10%). To address this inconsistency, we simulated the impact gardening process, accounting for distal ejecta, and tracked the compositional changes in the top 1 m layer at CE-5 landing area over time. Our results show that impact gardening brings deeper local materials to the surface, leading to a mixture that reduces the distal ejecta proportion within the top 1 m layer from which the soils were collected. After 2.0 Gyr of impact gardening, most materials of the top 1 m layer originate from the upper layer (depth <30 m) of local basalts, with distal ejecta as a minor component (∼2.7 vol.%), consistent with CE-5 soils analyses. Our results emphasize the profound influence of impact gardening on the composition of lunar soils.