A look at how human colonies could exist in space, from domed cities to underground bases, to orbital habitats, to hollowed-out asteroids. Also a look at how robots will play a role in space survival; how food will be grown; the advances in space suit and equipment technology; and a look at how resources could be gathered and processed to sustain such otherworldly colonies.
Space colonization (also called space settlement, or extraterrestrial colonization) is permanent human habitation outside of Earth. There are several arguments for space colonization that can be made: survival of human civilization and the biosphere from possible disasters (natural or man-made), and the huge resources in space for expansion of human society, being the two most common ones.
However, as of right now the building of a space colony would be a hugely difficult and massively expensive project. Space settlements would have to provide for all the material needs of hundreds or thousands of humans, in an environment out in space that is very hostile to human life. They would involve technologies, such as closed-loop life support systems, that have yet to be developed in any meaningful way. They would also have to deal with the as yet unknown issue of how humans would behave and thrive in such places long-term.
There have been no space colonies built so far, nor are there any governments or large-scale private organizations with a timetable for building any. However there have been many proposals, speculations and designs for space settlements that have been made, and there are a considerable number of space colonization advocates and groups. And several famous scientists, such as Freeman Dyson, have come out in favor of space settlement.
The primary argument that calls for space colonization as a first-order priority is as insurance of the survival of human civilization, by developing alternative locations off Earth where humankind could continue in the event of natural and man-made disasters.
Theoretical physicist and cosmologist Stephen Hawking has argued for space colonization as a means of saving humanity, in 2001 and 2006. In 2001 he predicted that the human race would become extinct within the next thousand years, unless colonies could be established in space. The more recent one in 2006 stated that mankind faces two options: Either we colonize space within the next two hundred years and build residential units on other planets or we will face the prospect of long-term extinction.
Louis J. Halle, formerly of the United States Department of State, wrote in Foreign Affairs (Summer 1980) that the colonization of space will protect humanity in the event of global nuclear warfare. The physicist Paul Davies also supports the view that if a planetary catastrophe threatens the survival of the human species on Earth, a self-sufficient colony could "reverse-colonize" Earth and restore human civilization. The author and journalist William E. Burrows and the biochemist Robert Shapiro proposed a private project, the Alliance to Rescue Civilization, with the goal of establishing an off-Earth backup of human civilization.
J. Richard Gott has estimated, based on his Copernican principle, that the human race could survive for another 7.8 million years, but it isn't likely to ever colonize other planets. However, he expressed a hope to be proven wrong, because "colonizing other worlds is our best chance to hedge our bets and improve the survival prospects of our species"