Stanford Torus - V4Image cropped - click to view
Artwork of a Stanford Torus. This is a design for a space station proposed by NASA in 1975 at Stanford University. It consists of a torus with a radius of 1800km and a cross-sectional radius of 130m for the habitable section. The ring is connected to a central hub via a series of six spokes, which also allow transport from the hub to the habitable section. Rotating at one revolution a minute the station provides an artificial gravity equivalent to roughly 0.9 Earth gravities, and can house around 10,000 to 40,000 people. The station would be constructed at the Earth-Moon L5 Lagrangian point - that is, sharing the Moon's orbit but being 60 degrees behind it in phase.