Miranda.

Miranda is the innermost and smallest of the major Uranian satellites, so it was long expected to be simply a cratered snowball, devoid of endogenically derived surface features. Drawing on the observed geology, photometry and geophysical data, the authors examine various processes and properties that may have contributed to Miranda's evolution. The coronae, unique to Miranda, may have formed by relaxation of topographic highs, by lithospheric stress driven by density anomalies in the asthenosphere, or by diapirs either breeching the surface or feeding large-scale volcanic flooding through pre-existing crack structure. Current data are insufficient to choose among the competing scenarios, and there may have been significant differences in the process for each corona even if all have fundamentally similar origins. Miranda remains tantalizingly enigmatic, but comparison with other icy moons defines the variety of physical and chemical processes involved in their formation and evolution.