Could Uranus’s Moon Miranda Hide a Secret Ocean Beneath Its Icy Surface?

In the icy outskirts of our solar system, Uranus’s small moon Miranda has been giving planetary scientists pause for thought—specifically about the possible presence of an ocean hidden beneath its surface. A new study, titled Constraining Ocean and Ice Shell Thickness on Miranda from Surface Geological Structures and Stress Modeling, delves into this fascinating prospect, providing evidence that Miranda, long considered dormant, could be far more dynamic than previously thought.

A Surface of Surprises

Miranda is unique among Uranus's moons. The only images we have of this distant, icy satellite were captured during the Voyager 2 flyby in 1986. But even from these pictures, scientists could see that Miranda is unlike any other moon in the Uranian system. Its surface is peppered with strange, concentric ridges and enormous fault systems, known as “coronae.” These features suggest something rare for an icy satellite this size—a potentially active geological past, and maybe even a liquid ocean below.

The study in question analyzed images of Miranda’s craters, ridges, and furrows, comparing them to stress patterns generated in a simulation. The goal was to estimate the thickness of Miranda’s icy crust and to see if there could be an ocean beneath. Findings suggest that Miranda has a thin, brittle ice crust—just about 30 kilometers thick, overlying a possible 100-kilometer-deep subsurface ocean.

Tidal Stresses, Ice Cracks, and Potentially an Ocean

Miranda’s mysterious features likely owe their existence to gravitational forces. In the study, scientists used a stress model that simulates how different forces—like those from tidal movement and the thickening of the ice shell—affect the surface. They found that when the moon’s icy crust is thin, it’s more susceptible to cracking from tidal forces, which are amplified as Miranda orbits Uranus.

It’s this tidal stress that could have caused the brittle surface to fracture, creating Miranda’s signature ridged terrain. But if the ice shell is thin, something needs to be beneath it to prevent the surface from freezing solid—hinting at a deep ocean beneath the ice.

A New Candidate for Habitability?

If Miranda does indeed have an ocean, it would join the ranks of other “ocean worlds” in our solar system, like Europa and Enceladus, which are known for their subsurface water. And just like those moons, Miranda’s ocean could be more than just water; it may be mixed with ammonia or other substances, which would allow it to remain liquid despite the moon’s cold environment.

Even more exciting, if a liquid ocean exists on Miranda, this opens up the possibility of habitability. Scientists often look to places with liquid water as potential habitats for microbial life. While Miranda isn’t exactly hospitable by Earth standards, it’s possible that deep below the surface, where conditions may be warmer due to tidal heating, life could have a chance to develop.

A Need for a Closer Look

This research offers a tantalizing preview of what we might find if we took a closer look at Uranus and its moons. With the ever-improving technology of space exploration, some scientists hope for a new mission to Uranus, which could provide data that allows us to confirm, or refute, the presence of this hidden ocean.

The stakes are high. Discovering an ocean on Miranda would change our understanding of where oceans—and potentially life—might exist in our solar system. For now, Miranda’s secret ocean remains hypothetical, but thanks to studies like this one, it’s moving from the realm of science fiction to science fact.