Constraining Ocean and Ice Shell Thickness on Miranda from Surface Geological Structures and Stress Modeling

Abstract Images from the Voyager 2 mission revealed the small Uranian satellite Miranda to be a complex, dynamic world. This is exemplified by signs of recent geological activity, including an extensive fault system and the mysterious coronae. This has led to speculation that Miranda may have been tectonically active within the geologically recent past and could have hosted a subsurface liquid water ocean at the time. In this work, we aim to constrain the thickness ranges for the ice shell and potential subsurface ocean on Miranda. Here, we present the results for our geological mapping of craters, ridges, and furrows on the surface. We also present the results for our comparison of the geographic distribution of these features to the predicted geographic distribution of maximum tidal stress based on stress models. We model eccentricity tidal stress, ice shell thickening stress, true polar wander stress, and obliquity tidal stress and compare the predicted surface stress pattern for each to what pattern can be inferred from the surface geology. Our results show that a thin crust (≤30 km) is most likely to result in sufficient stress magnitude to cause brittle failure of ice on Miranda’s surface. Our results also suggest the plausible existence of a ≥100 km thick ocean on Miranda within the last 100–500 million yr. This has implications for the dynamical history of Miranda and its status as a potential ocean world.