Editing Artificial gravity (section)

{{Short description|Use of circular rotational force to mimic gravity}}
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[[File:The Agena Target Docking Vehicle at a distance of approximately 80 feet from the Gemini-11 spacecraft.jpg|thumb|[[Gemini 11]] tethered in 1966 the GATV-5006 [[Agena target vehicle]] performing various tests including a first artificial gravity test in a [[microgravity]] environment.]]
[[File:Nautilus-X ISS demo 1.png|thumb|Proposed [[Nautilus-X]] International space station centrifuge demo concept, 2011]]

'''Artificial gravity''' is the creation of an [[inertial force]] that mimics the effects of a [[Gravity|gravitational]] force, usually by [[Circular motion|rotation]].<ref name="iaaweb.org">{{Cite book |editor-last2=Yajima |editor-first2=Kazuyoshi |editor-last3=Paloski |editor-first3=William |editor-first1=Laurence |editor-last1=Young |url=https://iaaweb.org/iaa/Scientific%20Activity/Study%20Groups/SG%20Commission%202/sg22/sg22finalreportr.pdf |title=Artificial Gravity Research to enable Human Space Exploration |date=September 2009 |isbn=978-2-917761-04-5 |access-date=February 23, 2022 |archive-url=https://web.archive.org/web/20161013004743/http://iaaweb.org/iaa/Scientific%20Activity/Study%20Groups/SG%20Commission%202/sg22/sg22finalreportr.pdf |archive-date=October 13, 2016 |url-status=dead |publisher=[[International Academy of Astronautics]] }}</ref> 
Artificial gravity, or '''rotational gravity''', is thus the appearance of a [[centrifugal force]] in a [[rotating frame of reference]] (the transmission of [[centripetal acceleration]] via [[normal force]] in the non-rotating frame of reference), as opposed to the force experienced in [[linear acceleration]], which by the [[equivalence principle]] is indistinguishable from gravity.
In a more general sense, "artificial gravity" may also refer to the effect of linear acceleration, e.g. by means of a [[rocket engine]].<ref name="iaaweb.org"/>

Rotational simulated gravity has been used in simulations to help astronauts train for extreme conditions.<ref>{{cite journal | pmid = 18619137 | volume=79 | issue=7 | title=Space medicine at the NASA-JSC, neutral buoyancy laboratory | date=July 2008 | journal=[[Aerospace Medicine and Human Performance|Aviation, Space, and Environmental Medicine]] | pages=732–733 | last1 = Strauss | first1 = Samuel | issn = 0095-6562 | lccn = 75641492 | oclc = 165744230}}</ref> 
Rotational simulated gravity has been proposed as a solution in [[human spaceflight]] to the adverse [[Effect of spaceflight on the human body|health effects caused by prolonged weightlessness]].<ref name="clement2015">{{Cite tech report |last1=Clément |first1=Gilles |last2=Charles |first2=John B. |last3=Norsk |first3=Peter |last4=Paloski |first4=William H. |url=https://ntrs.nasa.gov/citations/20150009486 |title=Human Research Program Human Health Countermeasures Element: Evidence Report - Artificial Gravity |date=February 15, 2015 |publisher=[[NASA]] |archive-url=https://web.archive.org/web/20240312223508/https://ntrs.nasa.gov/api/citations/20150009486/downloads/20150009486.pdf |archive-date=March 12, 2024 |hdl=2060/20150009486 |url-status=live }}</ref> 
However, there are no current practical outer space applications of artificial gravity for humans due to concerns about the size and cost of a spacecraft necessary to produce a useful [[centripetal force]] comparable to the gravitational field strength on Earth (''g'').<ref name="popularmechanics.com">{{Cite magazine |last1=Feltman |first1=Rachel |date=May 3, 2013 |title=Why Don't We Have Artificial Gravity? |url=https://www.popularmechanics.com/space/rockets/a8965/why-dont-we-have-artificial-gravity-15425569/ |url-status=live |archive-url=https://web.archive.org/web/20220101150056/https://www.popularmechanics.com/space/rockets/a8965/why-dont-we-have-artificial-gravity-15425569/ |archive-date=January 1, 2022 |access-date=February 23, 2022 |magazine=[[Popular Mechanics]] |issn=0032-4558 |oclc=671272936 }}</ref>
Scientists are concerned about the effect of such a system on the inner ear of the occupants. The concern is that using centripetal force to create artificial gravity will cause disturbances in the inner ear leading to nausea and disorientation. The adverse effects may prove intolerable for the occupants.<ref name="ncbi.nlm.nih.gov">{{Cite journal|last1=Clément|first1=Gilles R.|last2=Bukley|first2=Angelia P.|last3=Paloski|first3=William H.|date=2015-06-17|title=Artificial gravity as a countermeasure for mitigating physiological deconditioning during long-duration space missions|journal=Frontiers in Systems Neuroscience|volume=9|page=92|doi=10.3389/fnsys.2015.00092|issn=1662-5137|pmc=4470275|pmid=26136665|doi-access=free}}</ref>