Color and Photometric Properties of Newly Formed Impact Craters on the Moon

Abstract Impact craters and subsequent secondary impacts from sparse distal ejecta alter the exposed lunar regolith and affect its maturity. Remotely sensed observations sample the upper few microns of regolith; therefore, our interpretations of the surface must account for alterations and localized churning from these impact events. We investigate several impact sites and examine the newly formed crater colors and photometric properties to gain insight into cratering mechanics and regolith alteration. Using temporal imaging, phase angle ratios, an empirical photometric function, and resolved Hapke parameter maps of the impact site, we map the exposure of immature material and identify distinct zones in the continuous ejecta layer that correspond to grain size or porosity differences. The proximal ejecta exhibit distinct high- and low-reflectance zones: color ratios indicate excavation of less mature material in the proximal high-reflectance zone, whereas the proximal low-reflectance zone is consistent with roughness and porosity changes in otherwise mature material. Furthermore, we identify distal reflectance rays that extend much farther (over 1000 crater diameters) than previous studies have measured or modeled. The absence of a corresponding visible color change in distal zones, coupled with phase-dependent contrast and Hapke inversions, indicates that distal darkening is dominated by increased photometric roughness from sparse particle impacts rather than deposition of compositionally distinct material. These results show that small impacts modify the lunar surface over much larger areas than previously recognized, reducing grain- and facet-level exposure times to space weathering and implying faster, more spatially extensive regolith gardening.