Iapetus
Saturn's third largest moon, settled and quarried for ice, with a station in orbit and a helium-3 refinery on the surface, and the only large moon from which the rings are clearly visible.
Iapetus is the third largest moon of Saturn and one of the settled bodies of the outer Solar System, with a sizable resident population, a station in orbit and a helium-3 refinery on the surface. Giovanni Domenico Cassini discovered it in October 1671. The moon is heavily cratered and neither spherical nor ellipsoid, bulging along a distinctive equatorial ridge and squashed at the poles, and it is mostly ice with only about a fifth of its mass in rock. Lights glitter across its surface, marking the automated stations where that ice is quarried and split. Iapetus orbits much farther out than Titan and on the most inclined plane of Saturn's regular satellites, which makes it the only large moon with a clear view of the rings.
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