Editing Liquid oxygen (section)

==Uses==
[[File:Liquid oxygen, Bagram Airfield, Afghanistan 4.jpg|thumb|A [[U.S. Air Force]] technician transfers liquid oxygen to a [[Lockheed Martin C-130J Super Hercules]] aircraft at the [[Bagram Airfield]], Afghanistan.]]
In commerce, liquid oxygen is classified as an [[industrial gas]] and is widely used for industrial and medical purposes. Liquid oxygen is obtained from the [[oxygen]] found naturally in [[air]] by [[fractional distillation]] in a [[Air separation|cryogenic air separation plant]].{{Citation needed|date=March 2025}}
[[File:Liquid Oxygen.png|thumb|Insulated evaporator and storage container setup for liquid oxygen]]
Air forces have long recognized the strategic importance of liquid oxygen, both as an oxidizer and as a supply of gaseous oxygen for breathing in hospitals and high-altitude aircraft flights. In 1985, the USAF started a program of building its own oxygen-generation facilities at all major consumption bases.<ref>Arnold, Mark. [https://web.archive.org/web/20170315000548/http://www.dtic.mil/get-tr-doc/pdf?AD=ADA581789 1U.S. Army Oxygen Generation System Development]. RTO-MP-HFM-182. dtic.mil</ref><ref>{{cite book|url=https://books.google.com/books?id=LVfaBwAAQBAJ&pg=PA150|title=Advances in Cryogenic Engineering: Proceedings of the 1957 Cryogenic Engineering Conference, National Bureau of Standards Boulder, Colorado, August 19–21, 1957|author=Timmerhaus, K. D.|date=8 March 2013|publisher=Springer Science & Business Media|isbn=978-1-4684-3105-6|pages=150–}}</ref>

=== In rocket propellant ===
{{see also|Liquid rocket propellant}}
[[File:Liquid Oxygen (LOX) ball at the CCAFS SLC-40.jpg|thumb|SpaceX's liquid oxygen ball at [[Kennedy Space Center|Cape Canaveral]]]]
Liquid oxygen is the most common [[Cryogenic fuel|cryogenic]] liquid [[oxidizer]] propellant for [[spacecraft propulsion|spacecraft rocket]] applications, usually in combination with [[liquid hydrogen]], [[kerosene]] or [[liquid methane|methane]].<ref name="nsf20140307">{{cite news |last=Belluscio|first=Alejandro G. |title=SpaceX advances drive for Mars rocket via Raptor power |url=http://www.nasaspaceflight.com/2014/03/spacex-advances-drive-mars-rocket-raptor-power/ |access-date=March 13, 2014 |newspaper=NASAspaceflight.com |date=March 7, 2014 }}</ref><ref name="fg20121120">{{cite news|last=Todd |first=David |title=Musk goes for methane-burning reusable rockets as step to colonise Mars |url=http://www.flightglobal.com/blogs/hyperbola/2012/11/musk-goes-for-methane-burning.html |access-date=November 22, 2012 |newspaper=FlightGlobal Hyperbola |date=November 20, 2012 |quote=‘We are going to do methane,’ Musk announced as he described his future plans for reusable launch vehicles including those designed to take astronauts to Mars within 15 years, ‘The energy cost of methane is the lowest and it has a slight Isp (Specific Impulse) advantage over Kerosene’ said Musk adding, ‘and it does not have the pain in the ass factor that hydrogen has.’ ... SpaceX's initial plan will be to build a lox/methane rocket for a future upper stage codenamed Raptor. ... The new Raptor upper stage engine is likely to be only the first engine in a series of lox/methane engines. |url-status=dead |archive-url=https://web.archive.org/web/20121128070948/http://www.flightglobal.com/blogs/hyperbola/2012/11/musk-goes-for-methane-burning.html |archive-date=November 28, 2012 }}</ref>

Liquid oxygen was used in the [[Robert H. Goddard#First flight|first liquid fueled rocket]]. The [[World War II]]  [[V-2 rocket|V-2]] missile also used liquid oxygen under the name [[List of stoffs#List|''A-Stoff'' and ''Sauerstoff'']]. In the 1950s, during the [[Cold War]] both the United States' [[Redstone (rocket)|Redstone]] and [[Atlas (rocket)|Atlas]] rockets, and the [[USSR|Soviet]] [[R-7 Semyorka]] used liquid oxygen. Later, in the 1960s and 1970s, the ascent stages of the [[Saturn (rocket family)|Apollo Saturn rockets]], and the [[Space Shuttle main engines]] used liquid oxygen.{{Citation needed|date=March 2025}}

As of 2025, many active rockets use liquid oxygen: <!-- excluding retiring rockets -->
* [[Chinese space program]]
** [[China Aerospace Science and Technology Corporation|CASC]]: [[Long March 5]], [[Long March 6]], [[Long March 7]], [[Long March 8]], [[Long March 12]], ''[[Long March 9]]'' ''(under development)'', ''[[Long March 10]]'' ''(under development)''
** [[Galactic Energy]]: ''[[Pallas-1]]'' ''(under development)''
** [[i-Space (Chinese company)|i-Space]]: ''[[Hyperbola-3]]'' ''(under development)''
** [[LandSpace]]: [[Zhuque-2]], ''[[Zhuque-3]]'' ''(under development)''
** [[Orienspace]]: [[Orienspace#Gravity-2|''Gravity-2'']] ''(under development)''
** [[Space Pioneer]]: [[Tianlong-2]], ''[[Tianlong-3]]'' ''(under development)''
* Europe
** [[European Space Agency]]: [[Ariane 6]]
** [[Isar Aerospace]]: [[Spectrum (rocket)|''Spectrum'']] ''(under development)''
** [[Rocket Factory Augsburg]]: ''[[RFA One]]'' ''(under development)''
* [[Indian Space Research Organisation]]: [[Geosynchronous Satellite Launch Vehicle#Third stage|GSLV]], [[LVM3]]
* [[JAXA]] (Japan): [[H-IIA]], [[H3 (rocket)|H3]]
* [[Korea Aerospace Research Institute]]: [[Nuri (rocket)|Nuri]]
* [[Roscosmos]] (Russia): [[Soyuz-2]], [[Angara (rocket family)|Angara]]
* United States
** [[Blue Origin]]: [[New Shepard]], [[New Glenn]]
** [[Firefly Aerospace]]: [[Firefly Alpha]]
** [[NASA]]: [[Space Launch System]]
** [[Northrop Grumman]]: ''[[Antares 300]]'' ''(under development)''
** [[Rocket Lab]]: [[Rocket Lab Electron|Electron]], [[Rocket Lab Neutron|''Neutron'']] ''(under development)''
** [[SpaceX]]: [[Falcon 9]], [[Falcon Heavy]], [[SpaceX Starship|Starship]]
** [[United Launch Alliance]]: [[Atlas V]], [[Vulcan (rocket)|Vulcan]]