Other ocean-harboring moons, such as Jupiter’s Europa and Saturn’s Enceladus, are crisscrossed by fractures opened by strong tides that cause their oceans to bulge outward. Mimas, though freckled with craters, lacks any such cracks.
Planetary scientist Alyssa Rhoden of Arizona State University in Tempe and colleagues calculated whether Mimas’ icy shell could withstand the stress of a subsurface ocean pushing outward. Taking into account the moon’s elongated orbit, the researchers estimate that a subsurface ocean would produce tidal stresses larger than those on crack-riddled Europa. Mimas therefore probably doesn’t have an ocean, the researchers conclude February 24 in the Journal of Geophysical Research: Planets.