concept of permanent human habitation outside of Earth
Space colonization (also called space settlement, or extraterrestrial colonization) is permanent human habitation off the planet Earth.
Many arguments have been made for and against space colonization. The two most common in favor of colonization are survival of human civilization and the biosphere in the event of a planetary-scale disaster (natural or man-made), and the availability of additional resources in space that could enable expansion of human society. The most common objections to colonization include concerns that the commodification of the cosmos may be likely to enhance the interests of the already powerful, including major economic and military institutions, and to exacerbate pre-existing detrimental processes such as wars, economic inequality, and environmental degradation.No space colonies have been built so far. Currently, the building of a space colony would present a set of huge technological and economic challenges. 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 present cost of sending anything from the surface of the Earth into orbit (around $1400 per kg, or $640 per-pound, to low Earth orbit by the Falcon Heavy vehicle, expected to further decrease), a space colony would currently be a massively expensive project.
There are yet no plans for building space colonies by any large-scale organization, either government or private. However, many proposals, speculations, and designs for space settlements have been made through the years, and a considerable number of space colonization advocates and groups are active. Several famous scientists, such as Freeman Dyson, have come out in favor of space settlement.On the technological front, there is ongoing progress in making access to space cheaper (reusable launch systems could reach $20 per kg to orbit), and in creating automated manufacturing and construction techniques.
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