Similar Topography and Crater Retention Record yet Divergent Space Weathering Extents across Reiner Gamma on the Moon

Abstract Electrostatic levitation and migration of charged dust may occur during the formation of lunar swirls. Due to interaction between crustal magnetic anomalies and solar wind, immature fine-grained particles are predicted to preferentially migrate to bright on-swirl regions, yielding smaller elevation differences compared to dark off-swirl regions with time and also larger contrast of space weathering extents. Here we report that the off-swirl and on-swirl regions of Reiner Gamma, a representative lunar swirl, do not exhibit systematic elevation differences of over 2 m or distinct crater retention records at D ≥ 10 m. Surface regolith and fresh crater ejecta in on-swirl regions exhibit comparable reflectance spectra, but those of the surface regolith have shallower absorption bands and redder spectral slopes. Dark lanes sandwiched by on-swirl regions exhibit intermediate extent of space weathering compared to the background mare and on-swirl regions. The results indicate that dust migration either did not occur or yielded little topographic changes during the formation of Reiner Gamma, and deflection of solar wind by the local magnetosphere alone suffices to explain its origin.