Time‐Dependent Production Functions of Lunar Simple Craters on Layered Targets With Consideration of Topographic Degradation

Abstract

AbstractImpact bombardment changes target properties, and topographic degradation increases crater diameters. These effects potentially change the shape of lunar production function (PF), which is usually assumed to be constant with time. Using crater scaling laws, we model PFs (MPFs) formed by near‐Earth objects on two‐layer target models that have increasing regolith thickness with time. Model‐derived MPFs show a significantly elevated production rate for small lunar craters, which is consistent with a high regolith production rate during the last ~1 Ma. Further integrating the effect of topographic degradation, we model the time‐dependent observable PFs (MOPFs) from the MPFs. Comparing among MOPFs, MPFs, and the prevailing Neukum PF suggests that, for D = 10–1,000 m simple craters, applying MPFs and Neukum PF may cause the derived cumulative density of D > 1 km craters (i.e., N(1)) to differ from its real value by a factor up to ~3 and ~10, respectively.