Colonization of the outer Solar System of the four Galilean moons. Despite this, its volcanoes could be energy resources for the other moons, better to colonize. The Artemis Project proposed a plan to colonize Europa. Scientists would inhabit igloos and drill down into the Europan ice crust, exploring any subsurface ocean. The report also discusses use of air pockets for human habitation. Ganymede is the largest moon in the Solar System. Ganymede is the only moon with a magnetosphere, but it is overshadowed by Jupiter's magnetic field. Ganymede receives about 8 rem of radiation per day. Due to its distance from Jupiter's powerful radiation belt, Callisto
Solar System orbit of Neptune lies the area of the "trans-Neptunian region", with the doughnut-shaped Kuiper belt, home of Pluto and several other dwarf planets, and an overlapping disc of scattered objects, which is tilted toward the plane of the Solar System and reaches much further out than the Kuiper belt. The entire region is still largely unexplored. It appears to consist overwhelmingly of many thousands of small worlds—the largest having a diameter only a fifth that of Earth and a mass far smaller than that of the Moon—composed mainly of rock and ice. This region is sometimes described as the "third