Modeling the Evolution of Lunar Regolith: 2. Growth Rate and Spatial Distribution

Abstract

The evolution of regolith thickness induced by continuous impact events on the lunar surface provides valuable information about lunar geology and the bombardment history of the inner Solar System. In this study, we develop a Lunar Topography and Regolith Evolution Model based on the production and distribution of lunar regolith resulting from individual impact craters. Considering the changing impact flux, evolving target properties, topographic degradation process, and crater superposition, our model simultaneously simulates both the spatial and temporal evolution of lunar cratered topography and regolith thickness. The modeled regolith thickness generally aligns with results estimated by in situ seismic experiments and measurements of small crater morphology. Through our simulations, we establish a novel quantitative relation between regolith growth rate and time, providing new constraints on the impact flux trend and buffering trend in the regolith growth process. By comparing this new relation with that predicted by our analytical regolith evolution model, we reveal the significant influences of evolving target properties and regolith distribution on the regolith growth rate. Our modeled results also show that the regional regolith thickness follows a characteristic long‐tailed distribution with substantial lateral variations. Both the root‐mean‐square fluctuation and correlation length of lunar regolith increase with lateral scale and the surface age, which are ∼4.7 and 18 m on the hectometer scale at 3.5 Ga. All these results contribute to a better understanding of the regolith evolution process and can provide valuable insights into the lunar surface dynamics.