Identifying an index of subsurface volatiles on Mars through an analysis of impact crater morphometry using principal component analysis

Abstract

Layered ejecta craters comprise a significant fraction of the ejecta on Mars and may form from the excavation of subsurface volatiles, such as ice. A recent global catalogue identified extensive numbers of layered ejecta craters and their properties and is examined here. In this study over 10,000 single-layered and double-layered ejecta craters were analyzed by principal component analysis. Principal component analysis revealed the existence of four significant principal components for single-layered ejecta craters, and five for double-layered ejecta craters, which accounted for 73% and 80% of the sample variances, respectively. The first three PCs were interpreted as indices of impactor energy, target volatiles, and impactor angle. The fourth component for both morphologies was interpreted as a resurfacing index. The fifth component for double-layered craters was identified as an index of preservation of the impact feature. Using the putative target volatile index identified through principal component analysis, the spatial distribution of potential subsurface volatiles, both past and geologically recent, is mapped.