Stanford torus

Template:Short description Template:Use American English Template:For

The Stanford torus is a proposed NASA design<ref name=":1">Template:Cite web</ref> for a space settlement capable of housing 10,000 permanent residents.<ref>Template:Harvnb</ref> It is a type of rotating wheel space station, consisting of a ring with a diameter of about Template:Convert, its rotation providing about 1.0 g of artificial gravity.<ref name=":0">Template:Cite web</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 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>Template:Harvnb</ref> (Gerard O'Neill later proposed his Island One or Bernal sphere as an alternative to the torus<ref>Template:Cite book</ref>). "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),<ref name=tsiolkovsky1903>Template:Cite book</ref> Herman Potočnik (1923)<ref name=potockik>Template:Cite book</ref> and Wernher von Braun (1952),<ref>Template:Cite book</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 Template:Convert 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>Template:Harvnb</ref>

Sunlight is provided to the interior of the torus by a system of mirrors, including a large non-rotating primary solar mirror.<ref>Template:Cite web</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. Zero-gravity industry is performed in a non-rotating module attached to the hub's axis.<ref name="nasa c5">Template:Harvnb</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 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" />

The Stanford Torus design was not conceived for a single, isolated space settlement, but as part of a system for the colonization of space. Part of the people living in the colony would work in the construction of satellite solar power stations and new colonies, so that the habitat would be capable of self-replication, with a full system of multiple Stanford toruses being eventually built.<ref>Template:Cite web</ref><ref>Template:Cite web</ref>

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 L5 Lagrangian point.
Human population: 10,000.
Total mass: Template:Convert (including radiation shield (95% of total mass), habitat, and atmosphere).
Diameter: Template:Convert.
Circumference: 5,623.45 m (3.49 mi).
Rotation: 1 revolution per minute.
Temperature: Template:Convert
Radiation shield (non-rotating): Template:Convert thick raw lunar soil.<ref name=":0" />

Components

Habitation tube (torus proper) with a diameter of Template:Convert. 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 Template:Convert. 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 Template:Convert. 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 Template:Convert and a length of Template:Convert.
Spokes: 6 spokes of Template:Convert 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 Template:Convert 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

Template:Sticky header


Use<ref name=":0" />	Used land area	Number of levels	Total usable area<ref group=Note name=Note01/>	Height per level	Volume	Notes
Residential	Template:Convert	4	Template:Convert	Template:Convert	Template:Convert	Including dwelling units (Template:Convert/person), private exterior space and pedestrian access space (Template:Convert/person of total exterior 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	Template:Convert	2	Template:Convert	Template:Convert	Template:Convert	The authors of the study determined the space use from recommendations that call for 10 shops per 1000 people
Offices	Template:Convert	3	Template:Convert	Template:Convert	Template:Convert
Schools	Template:Convert	3	Template:Convert	Template:Convert	Template:Convert	With community multimedia center. The authors of the study calculated the space use for a student population of 10% of total population
Hospital	Template:Convert	1	Template:Convert	Template:Convert	Template:Convert	50-bed hospital with all the different needed facilities
Assembly (churches, community halls, theaters)	Template:Convert	1	Template:Convert	Template:Convert	Template:Convert
Recreation and entertainment	Template:Convert	1	Template:Convert	Template:Convert	Template:Convert	All commercial entertainment, including indoor activities and restaurants
Public open space	Template:Convert	1	Template:Convert	Template:Convert	Template:Convert	Parks, zoo, outdoor recreation (swimming, golf, playgrounds)
Service industry	Template:Convert	2	Template:Convert	Template:Convert	Template:Convert	Light service industry of personal goods, furniture, handicrafts, etc.
Storage	Template:Convert	4	Template:Convert	Template:Convert	Template:Convert	Wholesaling and storage
Transportation	Template:Convert	1	Template:Convert	Template:Convert	Template:Convert	Template:Convert 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)	Template:Convert	1	Template:Convert	Template:Convert	Template:Convert	Communication and telephone distribution
Waste and water treatment and recycling	Template:Convert	1	Template:Convert	Template:Convert	Template:Convert	Including water supply, return and recycling, and sewage treatment
Electrical supply and distribution	Template:Convert	1	Template:Convert	Template:Convert	Template:Convert	Including transformer substations
Miscellaneous	Template:Convert	2	Template:Convert	Template:Convert	Template:Convert
Total	Template:Convert	-	Template:Convert	-	Template:Convert

Agricultural uses

Template:Sticky header

Use<ref name=":0" />	Used land area	Number of levels	Total usable area<ref group=Note name=Note01/>	Height per level	Volume	Notes
Plant growing areas	Template:Convert	3	Template:Convert	Template:Convert	Template:Convert	List of crops: Template:Convert for sorghum; yield of Template:Convert Template:Convert for soybeans; yield of Template:Convert Template:Convert for wheat; yield of Template:Convert Template:Convert for rice; yield of Template:Convert Template:Convert for corn; yield of Template:Convert Template:Convert for vegetables; yield of Template:Convert. 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 Template:Convert of fruit per person each day, and also serving as ornamentation.
Animal areas	Template:Convert	3	Template:Convert	Template:Convert	Template:Convert	Stable herd of animals: 260,000 fish (Template:Convert for each one) 62,000 chickens (Template:Convert for each one) 28,000 rabbits (Template:Convert for each one) 1,500 cattle (Template:Convert 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.	Template:Convert	3	Template:Convert	Template:Convert	Template:Convert
Agriculture drying area	Template:Convert	3	Template:Convert	Template:Convert	Template:Convert

Totals

Used land area	Total usable area	Volume	Notes<ref name=":0" />
Template:Convert	Template:Convert	Template:Convert	Only part of the Template:Convert of land area and Template:Convert of volume available in the torus are used. The total land area is the result of multiplying the length of the torus at its center (Template:Convert) by the width at that same point (Template:Convert).

Construction

The torus would require nearly Template:Convert 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.<ref>Template:Harvnb</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 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, with a mass of around 500,000 tonnes, was chosen, to be attached to the center of the torus. 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 torus 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.<ref name="hein-pak-putz-revisited">Template:Cite journal</ref>

Gallery

Stanford torus configuration
Stanford torus structural cross section
Transportation system for the torus construction (1975)
A torus expanding from interconnected bolas or dumbbells
A NASA lunar base concept with a mass driver (the long structure that extends toward the horizon)
Stanford Torus-based generation ship, proposed by Project Hyperion<ref name="hein-pak-putz-revisited" />
External view of a Stanford torus with some of the radiation-shielding "chevron" mirrors removed to show interior space
Cutaway view of a Stanford torus