Ice geyser on Europa. Europa is the smallest of the four Galilean moons of Jupiter, and the second closet to the planet. Its surface is icy and relatively smooth. Impacting meteorites cause melting of the surface, allowing the water to smooth out before re-freezing. There is some evidence of large-scale movements of the ice, possibly supported by a liquid mantle and driven by thermal processes within the moon. Ice geysers have been seen on this moon, as in this illustration - jets of water-rich material spewing 200 km into space.