Space Station

A space station is an artificial structure designed for humans to live in outer space. So far only low earth orbit (LEO) stations are implemented, also known as orbital stations. A space station is distinguished from other manned spacecraft by its lack of major propulsion or landing facilities — instead, other vehicles are used as transport to and from the station. Space stations are designed for medium-term living in orbit, for periods of weeks, months, or even years. The only space station currently in use is the International Space Station. Previous ones are the Almaz, Salyut series, Skylab and Mir.

Space stations are currently as of 2007 used to study the effects of long-term space flight on the human body as well as to provide platforms for greater number and length of scientific studies than available on other space vehicles. Since the ill-fated flight of Soyuz 11 to Salyut 1, all manned spaceflight duration records have been set aboard space stations. The duration record for a single spaceflight is 437.7 days, set by Valeriy Polyakov aboard Mir from 1994 to 1995. As of 2008, three astronauts have completed single missions of over a year, all aboard Mir.
These stations have various issues that limit their long-term habitability, such as very low recycling rates, relatively high radiation levels and a lack of gravity. Some of these problems cause discomfort and long-term health effects. In the case of solar flares, all current habitats are protected by the Earth's magnetic field, and are below the Van Allen belts.

Future space habitats may attempt to address these issues, and are intended for long-term occupation. Some designs might even accommodate large numbers of people, essentially "cities in space" where people would make their homes. No such design has yet been constructed, since even for a small station, the current as of 2008 launch costs are not economically or politically viable.

Possible ways to deal with these costs would be building a large amount of rockets reusable rockets, In Situ Resource Utilisation or if space elevators are ever able to be constructed.