A new study has revealed that the icy moon of Uranus, Miranda, has experienced an episode of intense resurfacing from tidal heating.
The study found that the resurfacing resulted in the formation of at least three remarkable and unique surface features, polygonal-shaped regions called coronae, which are visible in Miranda's southern hemisphere, and each one is at least 200 km across.
Arden corona, the largest, has ridges and troughs with up to 2 km of relief, Elsinore corona has an outer belt that is approx. 80 km wide, relatively smooth, and elevated above the surrounding terrain by approx. 100 m and Inverness corona has a trapezoidal shape with a large, bright chevron at its center.
The northern hemisphere of Miranda was never imaged by the Voyager 2 spacecraft, so it is unknown whether additional coronae exist.
Using numerical models, Noah Hammond and Amy Barr showed that convection in Miranda's ice mantle likely formed the coronae and during convection, warm buoyant ice rose toward the surface, driving concentric surface extension beneath the locations of the coronae, causing the formation of extensional tectonic faults.
This style of resurfacing is similar to plate tectonics on Earth, in that convection is a primary driving force for surface deformation.
Hammond and Barr wrote that the internal energy that powered convection probably came from tidal heating, which would have occurred when Miranda was in an eccentric orbit, moving closer to and further from Uranus.
