Ganymede – Largest And Most Massive Moon Of Jupiter And It’s Oceans – Several Oceans?
In the 1970s, NASA scientists first suspected that Ganymede has a thick ocean between two layers of ice, one on the surface and one beneath a liquid ocean and atop the rocky mantle.
In the 1990s, NASA’s Galileo mission flew by Ganymede, confirming the moon’s sub-surface ocean. An analysis published in 2014, taking into account the realistic thermodynamics for water and effects of salt, suggests that Ganymede might have a stack of several ocean layers separated by different phases of ice, with the lowest liquid layer adjacent to the rocky mantle. Water–rock contact may be an important factor in the origin of life.
Size comparison of Earth, the Moon, and Ganymede.