Stanford torus

The Stanford torus was proposed during the 1975 NASA Summer Study, (Gerard O'Neill later proposed his Island One or Bernal sphere as an alternative to the torus). "Stanford torus" refers only to this particular version of the design, as the concept of a ring-shaped rotating space station was previously proposed by Konstantin Tsiolkovsky ("Bublik-City", 1903),{{cite book ==Design==

The Stanford torus (the proposed 10,000 people habitat described in the 1975 Summer Study, to be distinguished from other rotating wheel space station designs) consists of a torus, or doughnut-shaped ring, that is in diameter and 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. Sunlight is provided to the interior of the torus by a system of mirrors, including a large non-rotating primary solar mirror. The ring is connected to a hub via a number of "spokes", which serve as conduits for people and materials travelling to and from the hub. Since the hub is at the rotational axis of the station, it experiences the least artificial gravity and is the easiest location for spacecraft to dock. Zero-gravity industry is performed in a non-rotating module attached to the hub's axis. The interior space of the torus itself is used as living space, and is large enough that a "natural" environment can be simulated; 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. Chosen shape The 1975 NASA Summer Study evaluated several options for the space habitat design, including spherical and cylindrical shapes, in addition to the toroidal one. The torus was chosen as the best option, among other reasons, because it minimized the amount of mass required to have the same area and radius of rotation. General characteristics • Location: Earth–Moon L5 Lagrangian point. • Human population: 10,000. • Total mass: (including radiation shield (95% of total mass), habitat, and atmosphere). • Diameter: . • Circumference: 5,623.45 m (3.49 mi). • Rotation: 1 revolution per minute. • Temperature: • Radiation shield (non-rotating): thick raw lunar soil. Components • Habitation tube (torus proper) with a diameter of . 2/3 of its surface consists of aluminum plates and the remaining 1/3 is filled with glass windows mounted on aluminum ribs, to allow sunlight to enter inside the torus. • Non-rotating main mirror that directs sunlight towards the central hub. • Central hub with a diameter of . Secondary mirrors around the central hub direct sunlight towards the habitation tube. • Fabrication sphere (non-rotating), connected to central hub's South Pole, with a diameter of . It is also connected to a solar furnace and the habitat radiator. • Docking module (non-rotating), connected to central hub's North Pole, with a diameter of and a length of . • Spokes: 6 spokes of diameter, connecting the central hub with the habitation tube. They have elevators, power cables, and heat exchange pipes between the torus and the hub. Area and volume allocation The circumference of the torus proper (about in all) would be divided into 6 sections of equal length. 3 of the sections would be used for agriculture and the remaining 3 for residential uses. Agricultural and residential sections would alternate. A central plain would run through the full length of the torus. To gain space, structures would be terraced over the curved walls of the torus, while many commercial facilities (such as large shops, light industry or mechanical facilities) would be below the level of the central plain. According to the figures included in the study, the plain's floor would be about 1/4 of tube's diameter over the torus bottom, and each spoke would connect at the center of one of the 6 sections. Non-agricultural uses Agricultural uses Totals ==Construction==

The torus would require nearly of mass. Construction would use materials extracted from the Moon and sent to space using a mass accelerator. A mass catcher at L2 would collect the materials, transporting them to L5 where they could be processed in an industrial facility to construct the torus. Only materials that could not be obtained from the Moon would have to be imported from Earth. Asteroid mining is an alternative source of materials. ==World ship proposal==

The 2012 paper World Ships – Architectures & Feasibility Revisited proposed a generation ship (also called a world ship) based on the Stanford torus. The Stanford torus was chosen over O'Neill colony designs because of its detailed design that covers in-depth aspects such as life support systems and wall thickness. Four Stanford torus colonies would be stacked together, each with a population of 25,000 (bigger than the population of 10,000 for the original Stanford torus, while keeping the original general design and dimensions, and almost the same mass, that is increased by only 10% to 11 million tonnes), for a total population of 100,000, the minimum population size that the paper considers for a world ship. For the propulsion system, an upscaled version of the one designed in Project Daedalus was chosen. A single Daedalus-based system, with a mass of around 500,000 tonnes, would be attached to the centers of the four toruses. Daedalus would provide other additional features, such as power generation (solar energy, as used in the original Stanford Torus, is not available in the interstellar medium through which a world ship travels) and a dust shield to protect the toruses from interstellar dust impacts. The world ship would also need a fully automatic fail detection and self-repair system, to prevent failures from having catastrophic effects. ==Gallery==

File:Stanford torus configuration.gif|Stanford torus configuration File:Figure5.23 Stanford torus structural cross section.gif|Stanford torus structural cross section File:Figure4.13, Baseline transportation system, Space Settlements, A Design Study.NASA.gif|Transportation system for the torus construction (1975) File:Concepts from 1975 NASA Summer Study at Stanford.png|A torus expanding from interconnected bolas or dumbbells Image:Lunar base concept drawing s78 23252.jpg|A NASA lunar base concept with a mass driver (the long structure that extends toward the horizon) Image:Stanford Torus-based generation ship.png|Stanford Torus-based generation ship, proposed by Project Hyperion Image:Stanford torus under construction.jpg|External view of a Stanford torus with some of the radiation-shielding "chevron" mirrors removed to show interior space File:Stanford_Torus_cutaway.jpg|Cutaway view of a Stanford torus ==See also==