Impact Crater Morphometry on Pluto: Implications for Surface Composition and Evolution

Abstract

New Horizons showed that Pluto exhibits a wide range of geologic groups, with much of the surface modified by volatile ice processes. Impact craters are a valuable tool to investigate how these regions have evolved, as they record the effects of various modification mechanisms and retain information on the properties of the bedrock ice(s). In this work, we use Pluto’s crater population to quantify the extent of surface modification and identify variations in surface properties on Pluto. In this study, we have measured the relative depth of Pluto’s craters compared to minimally modified water-ice craters to interpret how the craters may have evolved and/or what the information tells us about the surface properties of the bedrock. We found a trend of increasing crater relative depth from southeast to northwest that may reflect the conditions of an ancient surface when a thicker layer of volatile ice may have existed, possibly changed by polar wander after the Sputnik impact. We have identified anomalously deep craters across Pluto’s surface, with a concentration in Cthulhu Macula, suggesting different bedrock-ice properties in this region. Other deep craters may be influenced by extraneous factors, such as impactor speed. Overall, this study expands on our understanding of the evolution and composition of Pluto’s surface and sets a road map for further investigations into Pluto’s surface evolution. © 2023. The Author(s). Published by the American Astronomical Society.