New research indicates internal oceans on small icy moons may boil due to pressure drops from tidal melting

UC Davis researchers find that melting ice shells on small moons like Enceladus and Mimas can cause internal oceans to boil, shaping unique surface features.

By: AXL Media

Published: Mar 2, 2026, 10:36 AM EST

Source: The information in this article was sourced from ScienceDaily

Tidal Forces and the Evolution of Icy Moons

The moons of the outer solar system are characterized by thick ice shells that often hide vast liquid oceans. These worlds are primarily shaped by tidal heating, a process where the gravitational pull of massive host planets generates internal friction and heat. According to lead researcher Max Rudolph, these tidal forces fluctuate over millions of years, causing the ice shells to periodically melt and refreeze. This constant state of flux plays a critical role in the geological evolution of moons orbiting planets like Saturn and Uranus.

The Mechanics of Subsurface Boiling

In a study published in Nature Astronomy, researchers examined the physical consequences of a thinning ice shell. As tidal heating intensifies, the ice shell melts from the bottom up. Because liquid water is more dense than ice, this melting process leads to a significant drop in internal pressure. On smaller moons such as Enceladus, Mimas, and Miranda, this pressure reduction can be extreme enough to reach the triple point of water, a state where liquid, ice, and vapor coexist. Under these specific conditions, the hidden oceans beneath the surface begin to boil.

Geological Impact on Miranda and Enceladus

The phenomenon of boiling oceans provides a potential explanation for the "alien" landscapes observed by spacecraft like Voyager 2. On Miranda, the smallest of Uranus's major moons, researchers believe that subsurface boiling contributed to the formation of coronae, which are massive systems of ridges and towering cliffs. Similarly, the "tiger stripe" fractures on Saturn's moon Enceladus may be the result of intense internal pressures and thermal activity associated with the cycle of shell thinning and the resulting release of water vapor.