A geologic model for lunar ice deposits at mining scales

Water ice has been detected at the lunar poles, but existing and near-future orbital datasets do not have the capabilities to determine its horizontal and vertical distribution at meter to hundred-meter scales relevant for mining operations. Additionally, there has not yet been a coherent geologic model put forward for how ice deposits have formed and evolved that can be used to assist in planning prospecting campaigns or developing relevant hardware. Here, we propose a system model for understanding these deposits at scales of meters to hectares. The model considers sources of water ice, capture at and below the surface, and retention; it focuses heavily on impact gardening as a modifying process that drives changes in how ice is distributed. 3-dimensional stochastic impact simulations are then used to test the system model and explore how ice deposits might evolve over an area the size of a potential mining outpost. The simulation results showed ice concentrations should eventually become fairly homogeneous at meter to hectare scales due to impact gardening, and high concentrations are distributed randomly rather than clustered in Earth-like ore bodies. We found the best ice deposits for extracting likely exist 10s of cm deep or more, even in locations where ice is currently stable at the very surface. Terrestrial mining software was then used to create block models and grade/tonnage curves that can inform future in-situ resource utilization demonstration missions and future mining operations planning.