Icy Moon of Uranus, Miranda, was Deformed by Tidal Heating

Miranda is one of the most visually striking bodies in our solar system. Orbiting Uranus, it appears to have experienced an episode of intense resurfacing that resulted in the formation of at least three remarkable surface features: polygonal-shaped areas called coronae. Now, scientists have taken a closer look at these coronae to learn a bit more about the moon.

The coronae are visible in Miranda's southern hemisphere. Measuring at least 200 km across each, they were first spotted by Voyager 2.

In all, the researchers have found three coronae. The Arden corona, which is the largest, has ridges and roughs with up to 2 km of relief. The Elsinore corona, in contrast, has an outer belt that is about 80 km wide, relatively smooth and elevation above the surrounding terrain n by about 100 m. The Inverness corona has a trapezoidal shape with a large, bright chevron at its center.

So how did these coronae form? Using models, the researchers found that convention in Miranda's icy mantle probably formed these features. During convection, warm buoyant ice rose toward the surface and drove the concentric surface extension beneath the locations of the coronae. This, in turns, caused the formation of extensional tectonic faults.

In fact, it's likely that the internal energy that powered this convention is due to tidal heating. Tidal heating would have occurred when Miranda was in an eccentric orbit around Uranus, moving closer and further away from the planet. The tidal forces as work would have caused Miranda to stretch and then contract again due to gravity. This, in turn, would have generated excess energy that would have heated Miranda's icy shell.

The findings reveal a bit more about the coronae on Miranda. That said, the researchers still aren't sure whether Miranda's northern hemisphere might also have coronae, since it was never imaged by Voyager 2. That said, it's certainly possible, but further research is needed.

The findings are published in the journal Geology.