Ariel moon of Uranus may have hosted a massive subsurface ocean

A new study published in the journal Icarus suggests that Ariel, one of Uranus’s largest icy moons, may have hosted a massive subsurface ocean in its past. Researchers from the Planetary Science Institute and the University of North Dakota propose that this internal body of water could have reached depths of up to 170 kilometers, significantly exceeding the depths of Earth's oceans.

Led by researcher Caleb Strom and senior scientist Alex Patthoff, the study utilizes morphological mapping and orbital simulation models to explain the moon's geological features. The presence of smoothed plains suggests cryovolcanism, where mixtures of water ice, ammonia, and other volatiles erupted from the interior in a liquid or semi-fluid state.

The researchers propose that Ariel previously experienced an orbital eccentricity of 0.04. During this period, the gravitational pull from Uranus caused continuous deformation and internal frictional heating—estimated to be four times higher than the heating currently experienced by Jupiter's moon Europa. This mechanical tension likely caused the massive fracturing of the moon's icy crust.