Icy Moons Might Have Oceans That Briefly Boil, Study Suggests

Small icy moons in the outer solar system could harbour oceans that briefly get hot enough to boil under their frozen shells, a new study says. The researchers discovered that moons such as Mimas, Enceladus, and Miranda, already believed to house hidden seas, might experience sudden plunges in pressure as their ice shells thin. This sudden change may push parts of their oceans to a “triple point” where ice, liquid, and vapour coexist. Scientists believe these unusual conditions may still allow life to survive below the boiling layer.

Study Reveals Low-Temperature Boiling Could Shape Icy Moons' Surface Activity

According to a Nature Astronomy report, the study led by Maxwell Rudolph examined how thinning ice shells reduces pressure on subsurface oceans, triggering low-temperature boiling. Rudolph noted that this type of boiling occurs near 0°C, unlike the familiar high-heat boiling seen on Earth. The process could also open cracks that allow water from potentially habitable oceans to escape to the surface. Such features may explain the long-observed activity on Enceladus and the recent evidence of a young ocean inside Mimas.

Smaller icy moons may be more likely to reach boiling temperatures, say the researchers, with larger bodies such as Titania breaking instead. Such stress features might account for the surface appearance of the Uranian moons, including ridges resulting from melt and refreeze events in the past.

Boiling-Driven Gas Traps on Icy Moons May Reveal Hidden Oceans, Study Suggests

Researchers also suggest that boiling could release gases that later become trapped in icy structures called clathrates. Future studies will investigate how these gases influence surface geology and whether they may serve as indicators of hidden oceans.

If confirmed, this finding offers more evidence that icy moons are a good place to look for life elsewhere, even in regions of extreme changes.