A space settlement (also called a space habitat, spacestead, space city or space colony) 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 advocacy is supporting or advocating human activity in outer space. The advocated purposes range from orbital flight, space exploration, commercialization of space and space settlement, to outright space colonization.
There are many different individuals and organizations dedicated to space advocacy. They are usually active in educating the public on space-related subjects, lobbying governments for increased funding in space-related activities or supporting private space activities.
A space habitat (or habitation module) in a basic sense is any facility providing shelter and fulfilling habitational purposes in outer space. It is not to be confused with an extended space settlement, an arrangement of or infrastructure for multiple habitation facilities, in the sense of a space settlement. Space stations and theoretical extraterrestrial surface stations (or base station), such as a moonbase or Mars habitat, include or are basic space habitats.
The ISS was planned to get a now canceled dedicated Habitation Module.
Extraterrestrial settlement can be any type of permanent habitation outside of Earth, beyond its space boundary, such as: