There are generally three types of space colonies that are being proposed by scientists. These are: Colonies located on satellites or asteroids, colonies that are located on other planets and finally, completely artificial space colonies.
The idea of space colonies have long been discussed and written about in science fiction novels. In fact, it was a popular subject even during the infancy of this literary genre. As far back as 1869, Dr. John Desmond Bernal already thought up of the Bernal sphere, which is a rotating space colony that has a diameter of about 15 kilometers. It was filled with air and colonized at the equatorial area. The movement of the colonists will then create the centrifugal force that will simulate gravity.
During the 60s and 70s, more research into the possible creation of space colonies brought about an increase in its popularity. The Space Race also contributed to this popularity. Physicist Gerard O’Neill, was one of the more vocal thinkers that has been involved space colony design and advocacy. In 1969, he forwarded a very interesting question, “Is the surface of a planet really the right place for an expanding technological civilization?” All throughout the 70s he led workshops that studied a number of space colony designs.
There is a general belief that space colonies will become a reality in the future. This could be used for military, economic, commercial or personal uses. The hope is that space colonies will eventually also acquire the ability to produce more space colonies, which will mean that at some point, humans may be able to colonize the inhabitable universe.