structural:summarization, stylistic:style_transfer
A space settlement is a settlement in outer space, sustaining more extensively habitation facilities in space than a general space station or spacecraft. Possibly including closed ecological systems, its particular purpose is permanent habitation. No space settlement has been constructed yet, but many design concepts, with varying degrees of realism, have been introduced in science-fiction or proposed for actual realization. Space settlements include orbital settlements around the Earth or any other celestial body, as well as cyclers and interstellar arks, as generation ships or world ships. Space settlements are a form of extraterrestrial settlements, which more broadly includes habitats built on or within a body other than Earth, such as a settlement developed from a moonbase, a Mars habitat or an asteroid.