View source for Stanford torus

{{short description|Proposed NASA design for space habitat}}
{{for|fictional structures for living in space|Space stations and habitats in fiction}}
[[Image:Stanford torus external view by Don Davis AC76-0525.jpg|thumb|Exterior view of a Stanford torus. Bottom center is the non-rotating primary solar mirror, which reflects sunlight onto the angled ring of secondary mirrors around the hub. Painting by Donald E. Davis.]]
[[Image:Stanford Torus interior.jpg|thumb|Interior of a Stanford torus, painted by Donald E. Davis]]
[[Image:Stanford torus-Space Settlements-A Design Study-1977.png|thumb|Collage of figures and tables of Stanford Torus space habitat, from ''Space Settlements: A Design Study'' book. Charles Holbrow and Richard D. Johnson, NASA, 1977.]]

The '''Stanford torus''' is a proposed [[NASA]] design<ref name=":1">{{Cite web |date=2017-08-03 |title=Stanford Torus Space Settlement – NSS |url=https://nss.org/stanford-torus-space-settlement/ |access-date=2025-04-08 |language=en-US}}</ref> for a [[space settlement]] capable of housing 10,000 permanent residents.<ref>{{harvnb|Johnson|Holbrow|1977|loc=p. 1, "The Overall System", p. 60, Summary}}</ref> It is a type of [[rotating wheel space station]], consisting of a ring with a diameter of about 1.8 km, its rotation providing about 1.0 ''g'' of [[artificial gravity]].<ref name=":0">{{cite web |last1=Johnson |first1=Richard D. |last2=Holbrow |first2=Charles |year=1977 |title=Space Settlements: A Design Study |url=http://settlement.arc.nasa.gov/75SummerStudy/Table_of_Contents1.html |url-status=dead |archive-url=https://web.archive.org/web/20091214010802/http://settlement.arc.nasa.gov/75SummerStudy/Table_of_Contents1.html |archive-date=2009-12-14 |publisher=National Aeronautics and Space Administration}}</ref>

==History of the concept==
The Stanford torus was proposed during the 1975 NASA Summer Study,<ref name=":1" /> conducted at [[Stanford University]], with the purpose of exploring and speculating on designs for future [[space colonization|space colonies]], with the conclusions and the detailed proposal being published in 1977 in ''Space Settlements: A Design Study'' book, by Richard D. Johnson and [[Charles H. Holbrow]]<ref>{{harvnb|Johnson|Holbrow|1977|loc=pg VII, "Preface"}}</ref> ([[Gerard K. O'Neill|Gerard O'Neill]] later proposed his Island One or [[Bernal sphere]] as an alternative to the torus<ref>{{cite book|last=O'Neill|first=Gerard K.|authorlink=Gerard K. O'Neill|title=[[The High Frontier: Human Colonies in Space]]|year=1977|publisher=Bantam Books|page=149}}</ref>). "Stanford torus" refers only to this particular version of the design, as the concept of a [[Rotating wheel space station|ring-shaped rotating space station]] was previously proposed by [[Konstantin Tsiolkovsky]] ("Bublik-City", 1903),<ref name=tsiolkovsky1903>{{cite book 
|last1=Bekey 
|first1=Ivan 
|last2=Herman
|first2=Daniel
|date=January 1, 1985
|title=Space Stations and Space Platforms-Concepts, Design, Infrastructure, and Uses 
|url=https://arc.aiaa.org/doi/book/10.2514/4.865749 
|language=en 
|chapter=Space Station and Space Platform Concepts: A Historical Review
|chapter-url=https://arc.aiaa.org/doi/10.2514/5.9781600865749.0203.0263
|contribution-url-access=subscription
|pages=203–263
|doi=10.2514/5.9781600865749.0203.0263
|publisher=[[American Institute of Aeronautics and Astronautics]] 
|isbn=978-0-930403-01-0 }}</ref> [[Herman Potočnik]] (1923)<ref name=potockik>{{cite book 
|last1=Noordung (pseudonym) 
|first1=Hermann 
|orig-date=1929 |date=1993
|title=Das Problem der Befahrung des Weltraums: der Raketen-Motor 
|url=https://upload.wikimedia.org/wikipedia/commons/6/68/Herman_Poto%C4%8Dnik_Noordung_-_Das_Problem_der_Befahrung_des_Weltraums.pdf 
|language=de 
|location=Berlin 
|publisher=Richard Carl Schmidt & Co. 
|pages=136–144 
|isbn=3851320603 }}</ref> or [[Wernher von Braun]] (1952),<ref>{{cite book |last=von Braun |first=W. |authorlink=Wernher von Braun |title=Crossing the Final Frontier |publisher=Colliers |date=March 22, 1952}}</ref> among others.

==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 1.8{{nbs}}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% of total mass), 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 (non-rotating): {{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 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 {{convert|130|m|ft|abbr=on}}. 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 {{convert|100|m|ft|abbr=on}}. 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 {{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 grams of fruit per person each day, and also serving as ornamentation.
|-
|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 chickens (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
|}

==Construction==
The torus would require nearly 10 million tons of mass. Construction would use materials extracted from the [[Moon]] and sent to space using a [[mass accelerator]]. A [[mass catcher]] at [[Lagrangian point#L2|L2]] would collect the materials, transporting them to [[Lagrangian point#L4 and L5|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.<ref>{{harvnb|Johnson|Holbrow|1977|page=201}}</ref>

==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 tones), for a total population of 100,000, the minimum population size that the paper considers for a world ship. 

For the propulsion system, the one designed in [[Project Daedalus]] was chosen, to be attached to the center of the torus. Daedalus would provide other additional features, such as power generation and a dust shield to protect the torus from interstellar dust impacts.<ref name="hein-pak-putz-revisited">{{cite journal |last1=Hein |first1=Andreas M. |last2=Pak |first2=Mikhail |last3=Pütz |first3=Daniel |last4=Bühler |first4=Christian |last5=Reiss |first5=Philipp |title=World ships—architectures & feasibility revisited |journal=Journal of the British Interplanetary Society |date=2012 |volume=65 |issue=4 |page=119|url=https://www.researchgate.net/publication/236177990 }}</ref>

==Gallery==
<gallery heights='250' mode=packed>
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 [[Space habitat#Designs.2Fsolutions|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 (interstellar)|Project Hyperion]]<ref name="hein-pak-putz-revisited" />
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
</gallery>

==See also==
{{Portal|Spaceflight|Engineering}}
<!-- Please keep entries in alphabetical order & add a short description [[WP:SEEALSO]] -->
*[[Asteroid mining]]
*[[Bernal sphere]]
*[[Colonization of the Moon]]
*[[Rotating wheel space station]]
*[[O'Neill cylinder]]
*[[Bishop Ring (habitat)|Bishop ring]]
*[[Space colonization]]
* In fiction
**[[Aurora (novel)|''Aurora'' (novel)]]
**[[Gaea trilogy]]
**''[[Ringworld]]''
**[[Interstellar (film)|''Interstellar'' (film)]]
**[[Elysium (film)|''Elysium'' (film)]]
**''[[Mobile Suit Gundam Wing]]''
**[[Citizen_Sleeper|''Citizen Sleeper'' (videogame)]]

==Notes==
{{reflist|group=Note|refs=
<ref name=Note01>The total usable area does not always exactly match with the product of the used land area multiplied by the number of levels.</ref>
}}

==References==
{{reflist}}

==External links==
{{Commons category|Stanford Torus}}
*[https://upload.wikimedia.org/wikipedia/commons/f/ff/Space_Settlements_-_A_Design_Study_%281977%29.pdf ''Space Settlements: A Design Study''], 1977 book, where Stanford torus was described
*{{YouTube|UcO_BjXfhhc|Space Colonization: Report on Stanford Torus Stations – NASA Ames circa 1975}}
*[http://www.spacehabs.com/357392/station-construction/ Visualisation of stanford torus construction from an asteroid mining facility in 2010] {{Webarchive|url=https://web.archive.org/web/20130125012327/http://www.spacehabs.com/357392/station-construction/ |date=2013-01-25 }}

{{Space stations}}
{{Space colonization}}

[[Category:Space habitats]]
[[Category:Megastructures]]
[[Category:Hypothetical technology]]