Six Solar System Moons Likely Harbor Hidden Subsurface Oceans

Planetary scientists have identified at least six moons—Europa, Ganymede, Callisto, Enceladus, Titan, and several of Uranus's large satellites—as likely hosts of vast liquid water oceans beneath thick ice shells. The oceans are thought to be kept liquid by tidal flexing, radioactive decay, salts and ammonia, making them prime targets in the search for habitable environments beyond Earth.

Recent observations and computer modeling challenge earlier assumptions about how that water might be accessed. NASA’s Juno spacecraft data, analyzed by Steve Levin, suggest Europa’s ice shell averages about 29 km in thickness, a barrier taller than three Mount Everests. Modeling by Lujendra Ojha of Rutgers University shows that rising water would become turbulent, rapidly super‑cooled and form microscopic frazil ice that quickly clogs narrow fractures, limiting the chances of water reaching the surface and complicating the detection of potential biosignatures.