Editing Space settlement (section)

==Concepts==
===Base concepts===
The two common original concepts are the [[Bernal sphere]] and the [[O'Neill cylinder]].

====Dumbbell-shape assembly concept====
[[File:Curreri space habitat.png|thumb|A dumbbell-shaped self-sufficient and self-reproducible habitat for 10 persons]]
[[File:Concepts from 1975 NASA Summer Study at Stanford.png|thumb|Various concepts merging into a cylindrical station]]

A [[dumbbell]]-like spacecraft or habitat, connected by a cable to a [[counterweight]] or other habitat. This design has been proposed as a Mars ship, initial construction shack for a space habitat, and [[transhab|orbital hotel]]. It has a comfortably long and slow rotational radius for a relatively small station mass. Also, if some of the equipment can form the counter-weight, the equipment dedicated to artificial gravity is just a cable, and thus has a much smaller mass-fraction than in other concepts. For a long-term habitation, however, radiation shielding must rotate with the habitat, and is extremely heavy, thus requiring a much stronger and heavier cable.<ref name="minimized">{{cite conference | last= Curreri | first= Peter A. | title= A Minimized Technological Approach towards Human Self Sufficiency off Earth | conference= Space Technology and Applications International Forum (STAIF) Conference | location= Albuquerque, NM | url= https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070032685_2007018823.pdf |url-status=dead |archive-url=http://web.archive.org/web/20110606010920/http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070032685_2007018823.pdf |archive-date=2011-06-06}} 11–15 February 2007. Retrieved 18 December 2010</ref> This speculative design was also considered by the NASA studies.<ref>{{Cite web|url=https://settlement.arc.nasa.gov/75SummerStudy/Chapt4.html |title=Space Settlements: A Design Study -- Chapter 4: Choosing Among Alternatives |url-status=dead |archive-url=https://web.archive.org/web/20091103221336/https://settlement.arc.nasa.gov/75SummerStudy/Chapt4.html |archive-date=2009-11-03}}</ref> Small habitats would be mass-produced to standards that allow the habitats to interconnect. A single habitat can operate alone as a bola. However, further habitats can be attached, to grow into a "[[dumbbell]]" then a "bow-tie", then a ring, then a cylinder of "beads", and finally a framed array of cylinders. Each stage of growth shares more radiation shielding and capital equipment, increasing redundancy and safety while reducing the cost per person. This concept was originally proposed by a professional architect because it can grow much like Earth-bound cities, with incremental individual investments, unlike those that require large start-up investments. The main disadvantage is that the smaller versions use a large structure to support the radiation shielding, which rotates with them. In large sizes, the shielding becomes economical, because it grows roughly as the square of the colony radius. The number of people, their habitats, and the radiators to cool them grow roughly as the cube of the colony radius.

===Further concepts===
[[File:Bernal sphere interior.jpg|thumb|Interior of a Bernal sphere]]
* [[Bernal sphere#Island One|Island One]], a Bernal sphere settlement for about 10,000–20,000 people.
* [[Stanford torus]]: an alternative to Island One.
* Lewis One,<ref>{{cite web| url=http://alglobus.net/NASAwork/papers/RNR-91-018/RNR-91-018.html| title=Lewis One Space Colony| first=Al| last=Globus| access-date=2006-05-28}}</ref> a cylinder of radius 250&nbsp;m with a non-rotating radiation shielding. The shielding protects the micro-gravity industrial space, too. The rotating part is 450m long and has several inner cylinders. Some of them are used for agriculture.
* Island Three or [[O'Neill cylinder]], an even larger  cylindrical design (3.2<ref>{{Cite web |date=2017-08-03 |title=O’Neill Cylinder Space Settlement |url=https://nss.org/o-neill-cylinder-space-settlement/ |access-date=2025-01-09 |website=NSS |language=en-US}}</ref> or 4<ref>{{Cite web |date=2014-10-02 |title=How We Could Actually Build a Space Colony |url=https://www.popularmechanics.com/space/deep-space/a11351/how-we-could-actually-build-a-space-colony-17268252/ |access-date=2025-01-09 |website=Popular Mechanics |language=en-US}}</ref> km radius and 32 km long).
*[[McKendree cylinder]], another concept that would use carbon nanotubes, a McKendree cylinder is paired cylinders in the same vein as the Island Three concept, but each 460 km in radius and 4600 km long (versus 3.2-4 km radius and 32 km long in the Island Three).<ref>{{cite conference | title= Implications of Molecular Nanotechnology Technical Performance Parameters on Previously Defined Space System Architectures | conference= The Fourth Foresight Conference on Molecular Nanotechnology | first= Thomas Lawrence | last= McKendree | location= Palo Alto, California, USA | url= http://www.zyvex.com/nanotech/nano4/mckendreePaper.html#RTFToC17}} 9–11 November 1995.</ref>
* Kalpana One, revised,<ref name="Kalpana">{{cite web| url=http://alglobus.net/NASAwork/papers/2007KalpanaOne.pdf|title=The Kalpana One Orbital Space Settlement Revised|first=Al|last=Globus|access-date=2009-08-29}}</ref> a short cylinder with 250 m radius and 325 m length. The radiation shielding is 10 t/m<sup>2</sup> and rotates. It has several inner cylinders for agriculture and recreation. It is sized for 3,000 residents.<ref>{{Cite web |url=https://settlement.arc.nasa.gov/Kalpana/KalpanaOne.html |title=Kalpana One Space Settlement |url-status=dead |archive-url=https://web.archive.org/web/20130215204552/https://settlement.arc.nasa.gov/Kalpana/KalpanaOne.html |archive-date=2013-02-15}}</ref>
[[File:Kalpana One space station.png|thumb|Kalpana One concept]]
*Bubbleworld or Inside/Outside concept, originated by [[Dandridge MacFarlan Cole|Dandridge M. Cole]] in 1964,<ref name="Cole" /> calls for drilling a tunnel through the longest axis of a large metallic asteroid and filling it with a [[Volatility (chemistry)|volatile]] substance, possibly water. A very large solar reflector would be constructed nearby, focusing solar heat onto the asteroid, first to weld and seal the tunnel ends, then more diffusely to slowly heat the entire outer surface. As the metal softens, the water inside expands and inflates the mass, while rotational forces help shape it into a cylindrical form. Once expanded and allowed to cool, it can be spun to produce centrifugal pseudogravity, and the interior filled with soil, air and water. By creating a slight bulge in the middle of the cylinder, a ring-shaped lake can be made to form. Reflectors would allow sunlight to enter and to be directed where needed. This method would require a significant human and industrial presence in space to be at all feasible. The concept was popularized by [[science fiction]] author [[Larry Niven]] in his [[Known Space]] stories, describing such worlds as the primary habitats of the [[Belter (Niven)|Belters]], a civilization who had [[Colonization of the asteroids|colonized the asteroid belt]].
**"Bubbleworld" is also the name of a different concept of space settlement thought of by Dani Eder in 1995<ref>{{Cite web |title=Bubbleworld (Dani Eder) |url=https://yarchive.net/space/exotic/bubbleworld.html |access-date=2024-01-09 |website=yarchive.net}}</ref> (it is alternatively known as an Ederworld<ref>{{Cite web |title=Ederworlds |url=http://www.orionsarm.com/eg-article/48472f9d56859 |access-date=2024-01-09 |website=Orion's Arm - Encyclopedia Galactica}}</ref>). This is a relatively thin, spherical shell surrounding a mass of gas great enough to be held together by gravity. If hydrogen is used as the gas, the shell would have a radius of about 240,000 km. The outside of the shell would have a living space 2,400 km thick (filled with breathable air) with an additional outer shell (possibly made of 500 m of steel) above it to hold in the air.
* [[Terrarium (space habitat)|Asteroid terrarium]], a similar idea to the bubble world, in the 2012 novel ''[[2312 (novel)|2312]]'' by [[hard science fiction]] writer [[Kim Stanley Robinson]].
*[[Bishop Ring (habitat)|Bishop Ring]], a speculative design using [[carbon nanotube]]s: a torus 1000&nbsp;km in radius, 500&nbsp;km in width, and with atmosphere retention walls 200&nbsp;km in height. The habitat would be large enough that it could be "roofless", open to outer space on the inner rim.<ref>{{cite web | url= http://www.iase.cc/openair.htm | title= Open Air Space Habitats | first= Forrest | last= Bishop | website= iase.cc | publisher= Institute of Atomic-Scale Engineering | year= 1997}}</ref>
[[File:Orbitale.jpg|thumb|Artist's impression of a [[Bishop Ring (habitat)|Bishop Ring]].]]