Rock spatial densities on the rims and interiors of a group of Copernicus secondary craters

Prolonged Rock Exhumation at the Rims of Kilometer‐Scale Lunar Craters

“…We, thus interpret the boulders we see at old (>1.0 Ga) impact crater rims to have been exhumed as regolith migrates downslope via mass wasting processes into the crater interior and ejecta. This is also consistent with behavior expected as rims retreat with time (e.g., Xie et al, 2017), and with the interpretation of rocks found at Copernicus secondaries (Basilevsky et al, 2019).…”

“…The rate of ejecta breakdown established by that work was more recently utilized to infer an increase in the inner Solar System cratering rate in the last ∼290 Myr (Mazrouei et al, 2019). Additionally, several studies have utilized high-resolution images from the Lunar Reconnaissance Orbiter Camera (LROC) to manually count the number of boulders present in lunar ejecta deposits associated with craters of varying ages (e.g., Basilevsky et al, 2013Basilevsky et al, , 20152018;Li et al, 2018;Watkins et al, 2019). Those data were used to infer that most boulders ≥2 m on the lunar surface are destroyed in less than 300 Myr, likely due to meteoroid impacts and thermal fatigue of exposed rocks at the lunar surface (e.g., Hörz et al, 1975;Molaro et al, 2017;Ruesch et al, 2020).…”

Morphological Characterization of Decimeter‐ to Hectometer‐Scale Impact Craters at the Chang’E‐3/4/5 Landing Sites

“…On the 3D elevation map, we discovered some craters with a certain degree of asymmetry, indicating that they could be indiscernible secondary craters. The low impactor velocity and high impact obliquity of secondary craters may lead to a low d / D ratio as well (e.g., Basilevsky et al., 2019). But we found that craters with such asymmetric features are not obviously clustered and are impossible to be discriminated from their shapes in optical images, so the secondary craters cannot be specifically excluded from our results.…”