Miranda's Thick Regolith Indicates a Major Mantling Event from an Unknown Source

Abstract We investigated “muted” craters and scarps across Miranda’s cratered terrain. The morphologies of the muted are most consistent with modification by regolith deposition instead erosion or viscous relaxation. used three techniques to estimate thickness. (1) Analysis crater depth–Diameter ( d - D ) ratios near South Polar Terrain Chasma indicates that mantling their floors ranges from 0.3 1.2 km thick. Because older may have collected more than younger craters, true thickness be similar highest estimate. (2) size–frequency distributions terrain a 1.0 ± 0.2 km. (3) central mound within Alonso Crater 1.4 − 0.4 + 0.3 Verona Rupes represent an upper limit. These results indicate Miranda has one thickest regoliths in solar system, which important implications for interior thermal properties. Regolith appears mantle some Arden but not Elsinore Inverness, indicating oldest corona, contrary previous relative age estimates. In this scenario, event was ongoing during Arden’s formation before Inverness formed. propose possible sources thick regolith: giant impact ejecta, plume deposits, Uranian ring deposits. favor deposit hypothesis, is regolith’s large spatial extent, substantial thickness, slightly spectrally blue color. Follow-up studies rigorously investigate these scenarios required.