Editing Space colonization (section)

===Life support===
{{Further|Effect of spaceflight on the human body|Space medicine|Space food}}

[[File:Mars Food Production - Bisected.jpg|alt=|thumb|upright=1.2|Depiction of [[NASA]]'s plans to grow food on [[Mars]]]]

In space settlements, a life support system must recycle or import all the nutrients without "crashing." The closest terrestrial analogue to space life support is possibly that of a [[nuclear submarine]]. Nuclear submarines use mechanical life support systems to support humans for months without surfacing, and this same basic technology could presumably be employed for space use. However, nuclear submarines run "open loop"—extracting oxygen from seawater, and typically dumping [[carbon dioxide]] overboard, although they recycle existing oxygen.<ref>{{Cite web|url=https://www.airitilibrary.com/Publication/alDetailedMesh?DocID=P20100106003-200911-201004190023-201004190023-1642-1650|title=A Novel Application of the SAWD-Sabatier-SPE Integrated System for CO2 Removal and O2 Regeneration in Submarine Cabins during Prolonged Voyages|last=Huang|first=Zhi|website=Airiti Library|access-date=10 September 2018}}</ref> Another commonly proposed life-support system is a [[closed ecological system]] such as [[Biosphere 2]].<ref>{{cite book | title=Manmade Closed Ecological Systems | first1= I. I. |last1=Gitelson | first2= G. M. |last2=Lisovsky | first3= R. D. |last3=MacElroy | publisher= [[Taylor & Francis]] |date=2003 | isbn = 0-415-29998-5}}</ref>

==== Solutions to health risks ====
{{See also|Bioastronautics}}
Although there are many physical, mental, and emotional health risks for future colonists and pioneers, solutions have been proposed to correct these problems. [[Mars500]], [[HI-SEAS]], and SMART-OP represent efforts to help reduce the effects of loneliness and confinement for long periods of time. Keeping contact with family members, celebrating holidays, and maintaining cultural identities all had an impact on minimizing the deterioration of mental health.<ref>{{Cite web|url=https://anxiety.psych.ucla.edu/nasa-study-stress-management-and-resilience-training-for-optimal-performance-smart-op|title=NASA Study: Stress Management and Resilience Training for Optimal Performance (SMART-OP) – Anxiety and Depression Research Center at UCLA|language=en-US|access-date=4 March 2019|archive-url=https://web.archive.org/web/20190404154812/https://anxiety.psych.ucla.edu/nasa-study-stress-management-and-resilience-training-for-optimal-performance-smart-op|archive-date=4 April 2019|url-status=live}}</ref> There are also health tools in development to help astronauts reduce anxiety, as well as helpful tips to reduce the spread of germs and bacteria in a closed environment.<ref>{{Cite web|url=https://phys.org/news/2017-09-e-mental-health-tool-key-astronauts.html|title=E-mental health tool may be key for astronauts to cope with anxiety, depression in space|website=Phys.org|language=en-us|access-date=4 March 2019|archive-url=https://web.archive.org/web/20190404154812/https://phys.org/news/2017-09-e-mental-health-tool-key-astronauts.html|archive-date=4 April 2019|url-status=live}}</ref> Radiation risk may be reduced for astronauts by frequent monitoring and focusing work to minimize time away from shielding.<ref name=":0">{{Cite web |title=Keeping Astronauts Healthy in Space |url=https://www.nasa.gov/vision/space/travelinginspace/30sept_spacemedicine.html |url-status=live |archive-url=https://web.archive.org/web/20190202103324/https://www.nasa.gov/vision/space/travelinginspace/30sept_spacemedicine.html |archive-date=2 February 2019 |access-date=5 March 2019 |website=NASA.gov |publisher=NASA |language=en}}</ref> Future space agencies can also ensure that every colonist would have a mandatory amount of daily exercise to prevent degradation of muscle.<ref name=":0" />

====Radiation protection====
{{see also|Health threat from cosmic rays}}

[[Cosmic rays]] and [[solar flare]]s create a lethal radiation environment in space. In orbit around certain planets with magnetospheres (including Earth), the [[Van Allen belts]] make living above the atmosphere difficult. To protect life, settlements must be surrounded by sufficient mass to absorb most incoming radiation, unless magnetic or plasma radiation shields are developed.<ref name = spacecraftshielding>[http://engineering.dartmouth.edu/~simon_g_shepherd/research/Shielding/ Spacecraft Shielding] {{Webarchive|url=https://web.archive.org/web/20110928223044/http://engineering.dartmouth.edu/~simon_g_shepherd/research/Shielding/ |date=28 September 2011 }} engineering.dartmouth.edu. Retrieved 3 May 2011.</ref> In the case of Van Allen belts, these could be drained using orbiting tethers<ref name="mirnov1996">{{cite journal |last1=Mirnov |first1=Vladimir |last2=Üçer |first2=Defne |last3=Danilov |first3=Valentin |author-link3=Valentin Danilov |date=10–15 November 1996 |title=High-Voltage Tethers For Enhanced Particle Scattering In Van Allen Belts |journal=APS Division of Plasma Physics Meeting Abstracts |volume=38 |pages=7 |bibcode=1996APS..DPP..7E06M |oclc=205379064 |id=Abstract #7E.06}}</ref> or radio waves.<ref>{{Cite web |title=NASA Finds Lightning Clears Safe Zone in Earth's Radiation Belt - NASA |url=https://www.nasa.gov/news-release/nasa-finds-lightning-clears-safe-zone-in-earths-radiation-belt/ |access-date=11 December 2023 |language=en-US}}</ref>

Passive mass shielding of four metric tons per square meter of surface area will reduce radiation dosage to several [[Sievert#Yearly dose examples|mSv]] or less annually, well below the rate of some populated [[Background radiation#Natural background radiation|high natural background areas]] on Earth.<ref>NASA SP-413 [http://settlement.arc.nasa.gov/75SummerStudy/5appendE.html Space Settlements: A Design Study. Appendix E Mass Shielding] {{Webarchive|url=https://web.archive.org/web/20130227031349/http://settlement.arc.nasa.gov//75SummerStudy/5appendE.html |date=27 February 2013 }} Retrieved 3 May 2011.</ref> This can be leftover material (slag) from processing lunar soil and asteroids into oxygen, metals, and other useful materials. However, it represents a significant obstacle to manoeuvering vessels with such massive bulk (mobile spacecraft being particularly likely to use less massive active shielding).<ref name = spacecraftshielding/> Inertia would necessitate powerful thrusters to start or stop rotation, or electric motors to spin two massive portions of a vessel in opposite senses. Shielding material can be stationary around a rotating interior.

====Psychological adjustment====
The monotony and loneliness that comes from a prolonged space mission can leave astronauts susceptible to cabin fever or having a psychotic break. Moreover, lack of sleep, fatigue, and work overload can affect an astronaut's ability to perform well in an environment such as space where every action is critical.<ref>Clynes, Manfred E. and Nathan S. Kline, (1960) "Cyborgs and Space," Astronautics, September, pp.&nbsp;26–27 and 74–76.</ref>