Surface of Europa. Computer artwork of Europa with Jupiter in the background. The surface crust of Europa is made of water ice which form large blocks of ice, similar to polar ocean ice floes on Earth. The absence of large craters suggest that the surface is fairly new, having been refreshed in recent geological history. It is believed that this indicates a large body of water may exist beneath the surface crust. Europa is one of the four Galilean moons of Jupiter. It has a diameter of 3,100 kilometres (km) and its mass is two- thirds that of our Moon. It orbits Jupiter every 3 days, 13 hours, 14 minutes at a distance of 671,000 km.