Stanford Torus

Summarized from wikipedia published under the Attribution Share-Alike 4.0 Creative Commons license.

The Stanford Torus is a space habitat capable of housing 10,000 to 140,000 permanent residents. The Stanford torus is a ring-shaped rotating space station, previously proposed by Wernher von Braun and Herman Potočnik in the 20th century then elaborated in the 1975 NASA Summer Study which was held at Stanford, hence the name.

Torus

The Stanford Torus consists of a doughnut-shaped ring 1.8+ km in diameter that rotates once per minute to provide between 0.9 g and 1.0 g of artificial gravity on the inside of the outer ring via centrifugal force. Larger rings spinning a bit slower (so they are still 0.9 - 1.0 G) handle larger populations.

The interior space of the torus is used as living space, and is large enough that a "natural" environment can be approximated. the torus appears similar to a long, narrow, straight glacial valley whose ends curve upward and eventually meet overhead to form a complete circle. The population density is similar to a dense suburb, with part of the ring dedicated to agriculture and part to housing.

Mirrors

Sunlight is provided to the interior of the torus by a system of mirrors in space reflecting the local sunlight in through windows in the torus that face the center of the torus - the "up" side for residents in the torus.

Spokes

The ring is connected to a hub via spokes, which serve as conduits for people and materials traveling to and from the hub and also support and stabilize the rotating torus. The spokes rotate with the torus at their bottom ends (towards the torus) and the hub at the top.

Hub

The center of the of the space station, the hub itself does not spin and maintains a zero G non-rotating frame. Zero-G industry is performed in the non-rotating hub and spacecraft dock there. The spokes reach the hub and use some arrangement along the lines of bearings to handle the rotating spokes.

Construction

The torus requires nearly 10 million tons of mass. Construction would use materials extracted from the Moon and sent to space using a mass driver in the original proposal. Moons and asteroids provide the best sources of materials given TL-9 or better, with key high tech and precision equipment (and perhaps rare ingredients) imported from nearby planets or via star ships.

With more stable stars (less risk of radiation from solar storms) and more distance from the host star (less effect from storms and more misses) the radiation shield (95% of the mass) can be smaller. Interstellar locations would not require much radiation shield at all and would be much cheaper to build, then more expensive to move to their final location.

General characteristics

Proposed Location: Earth–Moon L5 Lagrangian point. Any Lagrangian point provides a fixed distance from the planet and/or moon. Orbits around stars can be used & typically are used in asteroid belts in systems without habitable planets.

Total mass: 10 million tons (including radiation shield (95%), habitat, and atmosphere), larger for populations > 10,000

Diameter: 1,790 m (1.11 mi) or larger

Circumference: 5,623.45 m (3.49 mi) or larger

Habitation tube diameter: 130 m (430 ft) possibly larger

Spokes: 6 spokes of 15 m (49 ft) diameter

Rotation: 1 revolution per minute

Radiation shield: 1.7 meters (5.6 feet) thick raw lunar soil, possibly less in many cases, possibly more for active stars and closer orbits.