Constraining ocean and ice shell thickness on Miranda from surface geological structures and stress modeling

Images from the Voyager 2 mission revealed the small (R ≈ 235 km) 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 presently host a subsurface liquid water ocean. 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 faults on the surface. We also present the results for our comparison of the location and orientation of these features to stress models, which predict where and in what spatial orientation the maximum tensile or compressional stress occurs on the surface during an orbital period. We model diurnal stress, ice-shell thickening stress, true polar wander stress, and obliquity stress and compare them to the surface geology. Our results show that moderate obliquity and polar wander stress are sufficient to produce the geologic deformation observed on Miranda. We also find that obliquity stress and polar wander produce stress orientations most consistent with the asymmetric antipodal stress pattern observed in Miranda’s surface geology. Furthermore, our results suggest the plausible existence of a ≥ 5 km thick ocean on Miranda within the last 100-500 million years. This has implications for the dynamical history of Miranda, and its status as a potential Ocean World.