The Cracks Of The Frankenmoon Of Uranus

It is one of the oddest moons in the solar system. Miranda, a small, icy moon of Uranus, is covered in giant fault canyons 12 times as deep as the Grand Canyon, giving it a unique look leading to it being called a 'Frankenstein moon'. Now, researchers say they have finally discovered why it looks so unusual. Despite its relatively small size, Miranda appears to have experienced an episode of intense resurfacing that resulted in the formation of at least three remarkable and unique surface features -- polygonal-shaped regions called coronae.

Inverness corona has a trapezoidal shape with a large, bright chevron at its center.  The giant fault canyons are as much as 12 times as deep as the Grand Canyon. Due to Miranda's low gravity and large cliffs, a rock dropped off the edge of the highest cliff would take a full 10 minutes to reach the foot of the cliff.  All of Uranus' larger moons, including Miranda, are thought to consist mostly of roughly equal amounts of water ice and silicate rock. 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 from Brown proved that convection in Miranda's ice mantle likely formed the coronae. 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,' they wrote.Hammond and Barr write that the internal energy that powered convection probably came from tidal heating. Tidal heating would have occurred when Miranda was in an eccentric orbit -- moving closer to and further from Uranus. This caused the tidal forces from Uranus to vary, periodically stretching and squeezing Miranda and generating heat in its ice shell.