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. In rocket propellant Liquid oxygen is the most common cryogenic liquid oxidizer propellant for spacecraft rocket applications, usually in combination with liquid hydrogen, kerosene or methane. Liquid oxygen was used in the first liquid fueled rocket. The World War II V-2 missile also used liquid oxygen under the name A-Stoff and Sauerstoff. In the 1950s, during the Cold War both the United States' Redstone and Atlas rockets, and the Soviet R-7 Semyorka used liquid oxygen. Later, in the 1960s and 1970s, the ascent stages of the Apollo Saturn rockets, and the Space Shuttle main engines used liquid oxygen. In 2020, many rockets used liquid oxygen: Chinese space program: Long March 5, and its derivations Long March 6, Long March 7 Indian Space Research Organisation: GSLV JAXA (Japan): H-IIA and H3 (under development) Roscosmos (Russia): Soyuz-2 and Angara (under development) ESA (EU): Ariane 5 and Ariane 6 (under development) Korea Aerospace Research Institute (South Korea): KSLV-1 and KSLV-II United States SpaceX: Falcon 9, Falcon Heavy and Starship (under development) (liquid oxygen chilled to , 10% denser than at boiling temperature) United Launch Alliance: Atlas V, Delta IV, Delta IV Heavy, Vulcan (under development) Northrop Grumman: Antares 230+ Blue Origin: New Shepard and New Glenn (under development) Rocket Lab: Electron Firefly Aerospace: Firefly Alpha Virgin Orbit: LauncherOne History By 1845, Michael Faraday had managed to liquefy most gases then known to exist. Six gases, however, resisted every attempt at liquefaction and were known at the time as "permanent gases". They were oxygen, hydrogen, nitrogen, carbon monoxide, methane, and nitric oxide. In 1877, Louis Paul Cailletet in France and Raoul Pictet in Switzerland succeeded in producing the first droplets of liquid air. In 1883, Polish professors Zygmunt Wróblewski and Karol Olszewski produced the first measurable quantity of liquid oxygen. See also Oxygen storage Industrial gas Cryogenics Liquid hydrogen Liquid helium Liquid nitrogen List of Stoffs Natterer compressor Rocket fuel Solid oxygen Tetraoxygen References Rocket oxidizers Cryogenics Oxygen Industrial gases Liquids 1883 in science