Editing Interplanetary spaceflight (section)

==Design requirements for crewed interplanetary travel==
[[File:Nasa mars artificial gravity 1989.jpg|thumb|In the artistic vision, the spacecraft provides [[artificial gravity]] by spinning (1989).]]
[[File:Deep Space Transport.jpg|thumb|[[Deep Space Transport]] and [[Lunar Gateway]]]]

===Life support===
[[Life support system]]s must be capable of supporting human life for weeks, months or even years. A breathable atmosphere of at least {{cvt|35|kPa}} must be maintained, with adequate amounts of oxygen, nitrogen, and controlled levels of carbon dioxide, trace gases and water vapor.

In October 2015, the [[NASA Office of Inspector General]] issued a [[Effect of spaceflight on the human body|health hazards report]] related to [[human spaceflight]], including a [[human mission to Mars]].<ref name="AP-20151029">{{cite news |last=Dunn |first=Marcia |title=Report: NASA needs better handle on health hazards for Mars |url=http://apnews.excite.com/article/20151029/us-sci-space-travel-health-6dfd5b2c76.html |date=October 29, 2015 |work=[[AP News]] |access-date=October 30, 2015 |archive-date=January 30, 2019 |archive-url=https://web.archive.org/web/20190130041700/http://apnews.excite.com/article/20151029/us-sci-space-travel-health-6dfd5b2c76.html |url-status=live }}</ref><ref name="NASA-20151029oig">{{cite web |author=Staff |title=NASA's Efforts to Manage Health and Human Performance Risks for Space Exploration (IG-16-003) |url=https://oig.nasa.gov/audits/reports/FY16/IG-16-003.pdf |date=October 29, 2015 |work=[[NASA]] |access-date=October 29, 2015 |archive-date=October 9, 2022 |archive-url=https://ghostarchive.org/archive/20221009/https://oig.nasa.gov/audits/reports/FY16/IG-16-003.pdf |url-status=dead }}</ref>
<!--In practice on the [[International Space Station]], the [[ISS ECLSS#Elektron|Elektron]] oxygen generator unit has been temperamental. (Weasel words, compare it to some other O2 generator; or do all O2 generators require maintenance?) -->

===Radiation===
Once a vehicle leaves [[low Earth orbit]] and the protection of Earth's magnetosphere, it enters the [[Van Allen radiation belt]], a region of high [[Ionizing radiation|radiation]]. Beyond the Van Allen belts, radiation levels generally decrease, but can fluctuate over time.<ref>{{cite web |title=Radiation Belts -- Fun Facts |url=https://www.nasa.gov/mission_pages/rbsp/mission/fun-facts.html |website=NASA |date=18 March 2015 |access-date=19 October 2021 |archive-date=3 November 2021 |archive-url=https://web.archive.org/web/20211103015724/https://www.nasa.gov/mission_pages/rbsp/mission/fun-facts.html |url-status=dead }}</ref> These high energy [[cosmic rays]] pose a [[Health threat from cosmic rays|health threat]]. Even the minimum levels of radiation during these fluctuations is comparable to the current annual limit for astronauts in low-Earth orbit.<ref>{{cite journal |last1=Mewaldt |title=The Cosmic Ray Radiation Dose in Interplanetary Space – Present Day and Worst-Case Evaluations |journal=International Cosmic Ray Conference |date=2005 |volume=2 |issue=29 |page=433 |bibcode=2005ICRC....2..433M |url=http://www.srl.caltech.edu/ACE/ASC/DATA/bibliography/ICRC2005/usa-mewaldt-RA-abs1-sh35-oral.pdf |access-date=19 October 2021 |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304053415/http://www.srl.caltech.edu/ACE/ASC/DATA/bibliography/ICRC2005/usa-mewaldt-RA-abs1-sh35-oral.pdf |url-status=live }}</ref>

Scientists of [[Russian Academy of Sciences]] are searching for methods of reducing the risk of radiation-induced [[cancer]] in preparation for the mission to Mars. They consider as one of the options a life support system generating drinking water with low content of [[deuterium]] (a stable [[Isotopes of hydrogen|isotope of hydrogen]]) to be consumed by the crew members. Preliminary investigations have shown that deuterium-depleted water features certain anti-cancer effects. Hence, deuterium-free drinking water is considered to have the potential of lowering the risk of cancer caused by extreme radiation exposure of the Martian crew.<ref>{{cite journal|pmid=14959623 | volume=37 | issue=6 | title=[Consideration of the deuterium-free water supply to an expedition to Mars] | date=2003 | journal=Aviakosm Ekolog Med | pages=60–3 | last1 = Siniak IuE | first1 = Turusov VS | last2 = Grigorev | first2 = AI | display-authors = etal  }}</ref><ref>{{cite journal|pmid=12575722|date=2003|last1=Sinyak|first1=Y|last2=Grigoriev|first2=A|last3=Gaydadimov|first3=V|last4=Gurieva|first4=T|last5=Levinskih|first5=M|last6=Pokrovskii|first6=B|title=Deuterium-free water (1H2O) in complex life-support systems of long-term space missions|volume=52|issue=7|pages=575–80|journal=Acta Astronautica|doi=10.1016/S0094-5765(02)00013-9|bibcode=2003AcAau..52..575S}}</ref>

In addition, [[coronal mass ejections]] from the [[Sun]] are highly dangerous, and are fatal within a very short timescale to humans unless they are protected by massive shielding.<ref>[http://www.popularmechanics.com/science/air_space/2076326.html?page=6 popularmechanics.com] {{webarchive|url=https://web.archive.org/web/20070814163410/http://www.popularmechanics.com/science/air_space/2076326.html?page=6 |date=2007-08-14 }}</ref><ref>{{cite journal | doi=10.1016/S1350-4487(99)00063-3 | pmid=11543148 | volume=30 | issue=3 | title=Shielding from solar particle event exposures in deep space | journal=Radiation Measurements | pages=361–382| year=1999 | last1=Wilson | first1=John W | last2=Cucinotta | first2=F.A | last3=Shinn | first3=J.L | last4=Simonsen | first4=L.C | last5=Dubey | first5=R.R | last6=Jordan | first6=W.R | last7=Jones | first7=T.D | last8=Chang | first8=C.K | last9=Kim | first9=M.Y | bibcode=1999RadM...30..361W }}</ref><ref>{{Cite web |url=http://www.nature.com/embor/journal/v4/n11/full/embor7400016.html |title=nature.com/embor/journal |access-date=2007-05-20 |archive-date=2010-08-21 |archive-url=https://web.archive.org/web/20100821050623/http://www.nature.com/embor/journal/v4/n11/full/embor7400016.html |url-status=live }}</ref><ref>{{Cite web |url=http://www.islandone.org/Settlements/MagShield.html |title=islandone.org/Settlements |access-date=2007-05-20 |archive-date=2016-04-05 |archive-url=https://web.archive.org/web/20160405143918/http://www.islandone.org/Settlements/MagShield.html |url-status=dead }}</ref><ref>{{Cite web |url=http://iss.jaxa.jp/iss/kibo/develop_status_09_e.html |title=iss.jaxa.jp/iss/kibo |access-date=2007-05-20 |archive-date=2016-12-18 |archive-url=https://web.archive.org/web/20161218171852/http://iss.jaxa.jp/iss/kibo/develop_status_09_e.html |url-status=live }}</ref><ref>{{Cite web |url=http://yarchive.net/space/spacecraft/debris_shield.html |title=yarchive.net/space/spacecraft |access-date=2007-05-20 |archive-date=2016-03-08 |archive-url=https://web.archive.org/web/20160308005359/http://yarchive.net/space/spacecraft/debris_shield.html |url-status=live }}</ref><ref>[http://uplink.space.com/showflat.php?Board=sciastro&Number=44199 uplink.space.com] {{webarchive|url=https://web.archive.org/web/20040328165528/http://uplink.space.com/showflat.php?Board=sciastro |date=2004-03-28 }}</ref>

===Reliability===
Any major failure to a spacecraft en route is likely to be fatal, and even a minor one could have dangerous results if not repaired quickly, something difficult to accomplish in open space. The crew of the [[Apollo 13]] mission survived despite an explosion caused by a faulty oxygen tank (1970).<ref>{{Cite news |last=Chang |first=Kenneth |date=2020-04-13 |title=Apollo 13’s Astronauts Survived Disaster 50 Years Ago. Could It Happen Again? |url=https://www.nytimes.com/2020/04/13/science/apollo-13-anniversary.html |access-date=2025-03-15 |work=The New York Times |language=en-US |issn=0362-4331}}</ref>

===Launch windows===
[[File:EDP and CEV leaving orbit.jpg|thumb|right|[[Earth Departure Stage]]]]
For [[astrodynamics]] reasons, economic spacecraft travel to other planets is only practical within [[launch window|certain time windows]]. Outside these windows the planets are essentially inaccessible from Earth with current technology. This constrains flights and limits rescue options in the case of an emergency.<ref>{{Cite web |last=NSE |date=2023-03-29 |title=Launch Windows: Timing is Everything |url=https://newspaceeconomy.ca/2023/03/29/timing-is-everything/ |access-date=2024-06-16 |website=New Space Economy |language=en-US}}</ref>