space colonization

Space colonization (also called space settlement, or extraterrestrial colonization) is permanent human habitation off planet Earth. Many arguments have been made for space colonization. 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. On the technological front, there is ongoing progress in making access to space cheaper, and in creating automated manufacturing and construction techniques. This could in the future lead to widespread space tourism, which could be a stepping stone to space colonization.