Editing Stanford torus (section)

==Design==
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 1.8&nbsp;km 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]].<ref>{{harvnb|Johnson|Holbrow|1977|page=46}}</ref>

Sunlight is provided to the interior of the torus by a system of [[mirror]]s, including a large non-rotating primary solar mirror.<ref>{{Cite web |title=Powering the Stanford Torus |url=http://large.stanford.edu/courses/2016/ph240/martelaro2/ |access-date=2025-05-18 |website=large.stanford.edu}}</ref>

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. [[Space manufacturing|Zero-gravity industry]] is performed in a non-rotating module attached to the hub's axis.<ref name="nasa c5">{{harvnb|Johnson|Holbrow|1977|loc=Chap. 5}}</ref>

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 [[U-shaped valley|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.<ref name="nasa c5" />

=== 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.<ref name=":0" />

===General characteristics===
* Location: Earth–Moon [[Lagrangian point#L4 and L5|L5 Lagrangian point]].
* Human population: 10,000.
* Total mass: 10 million tons (including radiation shield (95%), habitat, and atmosphere).
* Diameter: {{convert|1790|m|mi|abbr=on}}.
* Circumference: 5,623.45 m (3.49 mi).
* Rotation: 1 [[revolution per minute]].
* Temperature: 23 ± 8 °C.
* Radiation shield: {{convert|1.7|m|ft|abbr=off|sp=us}} thick raw [[lunar soil]].<ref name=":0" />

===Components===
* Habitation tube (torus proper), with a diameter of {{convert|130|m|ft|abbr=on}}. 2/3 of its surface are made 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 {{convert|130|m|ft|abbr=on}}. Secondary mirrors around the central hub direct sunlight towards the habitation tube.
* Fabrication sphere, connected to central hub's ''South Pole'', with a diameter of {{convert|100|m|ft|abbr=on}}. It is also connected to a solar furnace and the habitat radiator.
* Docking module, connected to central hub's ''North Pole'', with a diameter of {{convert|15|m|ft|abbr=on}} and a length of {{convert|60|m|ft|abbr=on}}.
* Spokes: 6 spokes of {{convert|15|m|ft|abbr=on}} diameter, connecting the central hub with the habitation tube. They have elevators, power cables, and heat exchange pipes between the torus and the hub.<ref name=":0" />

=== Area and volume allocation ===
The circumference of the torus proper (about 5,600 m 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.<ref name=":0" />

==== Non-agricultural uses ====
{| class="wikitable"
|+
!Use<ref name=":0" />
!Used land area (m<sup>2</sup>)
!Number of levels
!Total usable area (m<sup>2</sup>)<ref group=Note name=Note01/>
!Height per level (m)
!Volume (m<sup>3</sup>)
!Notes
|-
|Residential
|120,000
|4
|490,000
|3
|1,470,000
|Including dwelling units, private exterior space and pedestrian access space. Modular housing, allowing for one-or two-level clustered homes, as well as grouped apartment buildings with 4 or 5 stories, and terraced homes taking advantage of the edges of the central plain that runs through the torus
|-
|Shops
|10,000
|2
|23,000
|4
|92,000
|The authors of the study determined the space use from recommendations that call for 10 shops per 1000 people
|-
|Offices
|3,300
|3
|10,000
|4
|40,000
|
|-
|Schools
|3,000
|3
|10,000
|3.8
|38,000
|With community multimedia center. The authors of the study calculated the space use for a student population of 10% of total population
|-
|Hospital
|3,000
|1
|3,000
|5
|15,000
|50-bed hospital with all the different needed facilities
|-
|Assembly (churches, community halls, theaters)
|15,000
|1
|15,000
|10
|150,000
|
|-
|Recreation and entertainment
|10,000
|1
|10,000
|3
|30,000
|All commercial entertainment, including indoor activities and restaurants
|-
|Public open space
|100,000
|1
|100,000
|50
|5,000,000
|Parks, zoo, outdoor recreation (swimming, golf, playgrounds)
|-
|Service industry
|20,000
|2
|40,000
|6
|240,000
|Light service industry of personal goods, furniture, handicrafts, etc.
|-
|Storage
|10,000
|4
|50,000
|3.2
|160,000
|Wholesaling and storage
|-
|Transportation
|120,000
|1
|120,000
|6
|720,000
|15 m width for typical streets. Ring road around the torus, at the edge of the central plain. Mass transport system consisting of a moving sidewalk, monorail, and minibus
|-
|Communication switching equipment (for 2800 families)
|500
|1
|500
|4
|2,000
|Communication and telephone distribution
|-
|Waste and water treatment and recycling
|40,000
|1
|40,000
|4
|160,000
|Including water supply, return and recycling, and sewage treatment
|-
|Electrical supply and distribution
|1,000
|1
|1,000
|4
|4,000
|Including transformer substations
|-
|Miscellaneous
|10,000
|2
|29,000
|3.8
|112,000
|
|-
|Total
|466,000
| -
|942,000
| -
|8,233,000
|
|}

==== Agricultural uses ====
{| class="wikitable"
!Use<ref name=":0" />
!Used land area (m<sup>2</sup>)
!Number of levels
!Total usable area (m<sup>2</sup>)<ref group=Note name=Note01/>
!Height per level (m)
!Volume (m<sup>3</sup>)
!Notes
|-
|Plant growing areas
|147,000
|3
|440,000
|15
|6,600,000
|38,000 m<sup>2</sup> for sorghum (yield of 83 g/m<sup>2</sup>/day), 235,000 m<sup>2</sup> for soybeans (yield of 20 g/m<sup>2</sup>/day), 72,000 m<sup>2</sup> for wheat (yield of 31 g/m<sup>2</sup>/day), 36,000 m<sup>2</sup> for rice (yield of 35 g/m<sup>2</sup>/day), 9,000 m<sup>2</sup> for corn (yield of 58 g/m<sup>2</sup>/day), 52,000 m<sup>2</sup> for vegetables (yield of 132 g/m<sup>2</sup>/day). Part of the plant production is used to feed livestock. Sorghum is used to obtain sugar. Fruit trees are grown in parks and residential areas, providing 250 g of fruit per person each day, and serving at the same time for ornamental purposes.
|-
|Animal areas
|17,000
|3
|50,000
|15
|750,000
|Stable herd of animals: 260,000 fish (0.1 m<sup>2</sup> for each one), 62,000 chicken (0.13 m<sup>2</sup> for each one), 28,000 rabbits (0.4 m<sup>2</sup> for each one), 1,500 cattle (4 m<sup>2</sup> for each one). Flexibility is allowed for other animals to replace parts of these numbers (for example, pigs would have area requirements between those of rabbits and cattle).
|-
|Food processing, collection, storage, etc.
|13,000
|3
|40,000
|15
|600,000
|
|-
|Agriculture drying area
|27,000
|3
|80,000
|15
|1,200,000
|
|}

==== Totals ====
{| class="wikitable"
!Used land area (m<sup>2</sup>)
!Total usable area (m<sup>2</sup>)
!Volume (m<sup>3</sup>)
!Notes<ref name=":0" />
|-
|670,000
|1,552,000
|17,383,000
|Only part of the 678,000 m<sup>2</sup> of land area and 69,000,000 m<sup>3</sup> of volume available in the torus are used
|}