Space Colonies

Gerard K. O'Neill proposed housing citizens of a technological civilization in large space stations he called "colonies," each with up to 20 million people [9], [10], [11]. These O'Neill style colonies were large cylinders with spherical end-caps, rotating to provide a standard 1 g of pseudogravity on the inner surface. O'Neill suggested that if made of steel such a colony might reasonably be 3.2 km in radius, and 32 km long [10].