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The "Dagwood Sandwich" Moon. Earlier models of Ganymede's oceans were based on the assumption that the existence of salt didn't change the nature of liquid very much with pressure. However, Dr. Vance and his colleagues found, through laboratory experiments, that salt does increase the density of liquids under the extreme conditions hidden deep within Ganymede and similar icy moons with subsurface bodies of water. Imagine adding table salt to a glass of water. Instead of increasing in volume, the liquid will actually shrink and become denser. The reason for this is that salt ions lure water molecules. "We are just beginning to try and figure out quantitatively how all this might smooth a surface," Dr. Thomas said in the May 17, 2013 New Scientist. Until 2004, no spacecraft had visited Saturn for more than twenty years. Pioneer 11 took the very first close-up images of Saturn when it flew past in 1979. After that flyby, Voyager 1 had its rendezvous about a year later, and in August 1981 Voyager 2 had its brief, but glorious, encounter. Nearly a quarter of a century then passed before new high-resolution images of this beautiful, ringed planet were beamed back to Earth.