Editing Space settlement (section)

===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.