The Destruction of Small Lunar Craters

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

“…Compared to the degradation of craters beyond hectometer scales, the topographic degradation changes the morphologies of meter‐scale craters very fast. The degradation simulation result shows that the lifetime of a 2‐meter‐diameter crater is ∼3.97 Myr, which is close to the estimated ∼5 Myr lifetime for the same size crater using the method in Basilevsky (1976). The simulation result shows that despite the meter‐scale craters may be young in age, the crater could also be highly degraded (e.g., the last two craters in Figure 5).…”

“…This phenomenon is well demonstrated by the morphometries of the five craters with decreasing freshness in Figure 5; Figure S11 in Supporting Information S1, whose d/D ratios decrease from 0.118 to 0.044, h r /D ratios decrease from 0.027 to 0.007, and inner wall slopes decrease from 26.5° to 7.0°. The morphological characteristics of the five craters are similar to those of the crater morphological classes (A, AB, B, BC, and C) in Basilevsky (1976), but meter-scale craters have lower relative depths and gentler inner wall slopes than those of kilometer-scale craters with corresponding classes.…”

“…The mean bidirectional slopes of the CE‐3, 4, and 5 landing regions are 9.5°, 7.7°, and 13.5°, respectively. The inner wall slope of a crater has a strong correlation with the d / D ratio (Stopar et al., 2017) and both of which could be used to characterize the crater morphometry (Basilevsky, 1976). Similar to the d – D relationship, crater inner wall slope also increases with the increasing crater diameter.…”

“…In addition, for simple craters, an older crater generally has a shallower depth than a younger crater of a similar diameter. Therefore, the depth/diameter ratio ( d / D ) is extensively used as an indicator of the relative age of a crater (Basilevsky, 1976). For a fresh crater under 15 km, the d / D ratio is ∼0.2 (Pike, 1974).…”

Timing and Origin of Compressional Tectonism in Mare Tranquillitatis

“…The sharp‐edged morphology and the relatively small size of the crisp wrinkle ridges and lobate scarps suggest a relatively young formation age in contrast to advanced degraded and heavily degraded features. Crisp features can crosscut craters with diameters of less than 50–100 m. Craters of these sizes are estimated to be of Copernican ages (<800 Ma; Wilhelms et al., 1987), because older craters of this size would have been infilled and degraded since then (Basilevsky, 1976; Fassett & Thomson, 2014; Trask, 1971). Thus, it is possible to establish a Copernican age, that is, an upper age limit of ∼800 Ma for these landforms.…”