O'Neill cylinder

Artist's depiction of a pair of O'Neill cylinders
A diagram of a pair of O'Neill cylinders (Island Three)

An O'Neill cylinder (also called an O'Neill colony) is a space settlement concept proposed by American physicist Gerard K. O'Neill in his 1976 book The High Frontier: Human Colonies in Space.[1] O'Neill proposed the colonization of space for the 21st century, using materials extracted from the Moon and later from asteroids.[2]

An O'Neill cylinder would consist of two counter-rotating cylinders. The cylinders would rotate in opposite directions to cancel any gyroscopic effects that would otherwise make it difficult to keep them aimed toward the Sun. Each would be 5 miles (8.0 km) in diameter and 20 miles (32 km) long, connected at each end by a rod via a bearing system. Their rotation would provide artificial gravity.[1]

Interior view, showing alternating land and window segments
  1. ^ a b O'Neill, Gerard K. (1977). The High Frontier: Human Colonies in Space. New York: William Morrow & Company. ISBN 0-688-03133-1.
  2. ^ "Space Resources and Space Settlements,1977 Summer Study at NASA Ames Research Center". NASA. Archived from the original on 29 July 2012. Retrieved 20 October 2012.