Space colonization (also called space settlement, or extraterrestrial colonization) is permanent human habitation off planet Earth.

Many arguments have been made for space colonization.[1] The two most common are survival of human civilization and the biosphere in case of a planetary-scale disaster (natural or man-made), and the vast resources in space for expansion of human society.

No space colonies have been built so far. Currently, the building of a space colony would present a set of huge challenges both technological and economic. Space settlements would have to provide for nearly all (or 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 controlled ecological 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. Because of the huge cost of sending anything from the surface of the Earth into orbit (roughly $20,000 USD per kilogram) a space colony would be a massively expensive project.

There are no plans for building one by any large-scale organization, either government or private. 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. Several famous scientists, such as Freeman Dyson, have come out in favor of space settlement.[2]

On the technological front, there is ongoing progress in making access to space cheaper, and in creating automated manufacturing and construction techniques.[3] This could in the future lead to widespread space tourism, which could be a stepping stone to space colonization.[citation needed]

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.[4] 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.[5]

In 2005, then NASA Administrator Michael Griffin identified space colonization as the ultimate goal of current spaceflight programs, saying:

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.[7] 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.[8]

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".[9]

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Space colonization - Wikipedia, the free encyclopedia