Europa, Jupiter's Moon. Europa, like Mars, is one location in solar system where life is thought to be possible. At Europa this might be due to an underlying water ocean existing between icy crust, seen here, and a rocky core. In the same way life at Mars might be of the desert or hydrothermal kind, life at Europa might be of the polar type. Ridges, chaotic terrain, and some impact craters are Europa main features. Ridges are cracks in ice produced by tidal work by Jupiter. Reddish material might be a non-ice contaminant (salts e.g.) brought up from the underlying ocean. Most recently, Jupiter orbital world was thoroughly studied by NASA Galileo spacecraft. Europa is a bit smaller than Moon. picture courtesy NASA/JPL-Caltech/University of Arizona