Water worlds, but what else?

The surfaces of Jupiter’s icy Galilean moons (Europa, Ganymede and Calisto) are dominated by water ice, but there’s also a lot of other species. Some is sulfur, that has spewed out of volcanos on their sister moon, Io. There is also lots of salts too, chemicals like sodium chloride (yup, table salt) and magnesium sulfate (bath salts!) that come from the oceans below the icy surface. How do all these combine, what materials do they make? I’ve been exploring this for a while, and have some exciting new plans afoot with collaborators at the Open University, UK.