Editing Liquid rocket propellant (section)

==Methane==
Using liquid methane and liquid oxygen as propellants is sometimes called methalox propulsion.<ref>{{cite web |url=https://www.fastcompany.com/91027604/intuitive-machines-how-this-houston-start-up-is-making-space-history |title=Intuitive Machines: How this Houston startup is making space history |publisher=Fast Company}}</ref>
Liquid [[methane]] has a lower specific impulse than liquid hydrogen, but is easier to store due to its higher boiling point and density, as well as its lack of [[hydrogen embrittlement]]. It also leaves less residue in the engines compared to kerosene, which is beneficial for reusability.<ref name=pbt20140219>{{cite news |title=SpaceX propulsion chief elevates crowd in Santa Barbara |url=http://www.pacbiztimes.com/2014/02/19/spacexs-propulsion-chief-elevates-crowd-in-santa-barbara/ |date=2014-02-19 |publisher=Pacific Business Times |access-date=2014-02-22}}</ref><ref name=nsf20140307>{{cite web |last=Belluscio| first=Alejandro G. |title=SpaceX advances drive for Mars rocket via Raptor power |work=NASAspaceflight.com |date=2014-03-07 |url=http://www.nasaspaceflight.com/2014/03/spacex-advances-drive-mars-rocket-raptor-power/ |access-date=2014-03-07}}</ref> In addition, it is expected that its production on Mars will be possible via the [[Sabatier reaction]]. In NASA's [[Mars Design Reference Mission|Mars Design Reference Mission 5.0]] documents (between 2009 and 2012), [[Methane#fuel|liquid methane]]/[[liquid oxygen|LOX]] (methalox) was the chosen propellant mixture for the lander module.

Due to the advantages methane fuel offers, some private space launch providers aimed to develop methane-based launch systems during the 2010s and 2020s. The competition between countries was dubbed the Methalox Race to Orbit, with the [[LandSpace]]'s [[Zhuque-2]] methalox rocket becoming the first to reach orbit.<ref name="nsf-20230712">{{cite web |last=Beil |first=Adrian |url=https://www.nasaspaceflight.com/2023/07/zhuque-2-launch2/ |title=LandSpace claims win in the methane race to orbit via second ZhuQue-2 launch |work=[[NASASpaceFlight]] |date=12 July 2023 |access-date=16 July 2023}}</ref><ref>{{cite web|url=https://www.reuters.com/technology/space/china-beats-rivals-successfully-launch-first-methane-liquid-rocket-2023-07-12/ |title=China beats rivals to successfully launch first methane-liquid rocket |work=Reuters |date=12 July 2023 }}</ref><ref>{{cite web|url=https://everydayastronaut.com/second-flight-zhuque-2-2/ |title=Second Flight {{!}} ZhuQue-2 |website=Everyday Astronaut |date=12 July 2023 |first=Juan |last=I. Morales Volosín }}</ref>

{{As of|2025|January}}, three methane-fueled rockets have reached orbit. Several others are in development and two orbital launch attempts failed:
* [[Zhuque-2]] successfully reached orbit on its second flight on 12 July 2023, becoming the first methane-fueled rocket to do so.<ref>{{Cite web |last=Bell |first=Adrian |date=12 July 2023 |title=LandSpace claims win in the methane race to orbit via second ZhuQue-2 launch |url=https://www.nasaspaceflight.com/2023/07/zhuque-2-launch2/ |access-date=12 July 2023 |website=[[NASASpaceFlight.com]]}}</ref> It had failed to reach orbit on its maiden flight on 14 December 2022. The rocket, developed by [[LandSpace]], uses the [[TQ-12]] and [[TQ-11]] or [[TQ-15]]A engines.
* [[Vulcan Centaur]] successfully reached orbit on its first try, called Cert-1, on 8 January 2024.<ref>{{Cite web |author1=Josh Dinner |date=2024-01-08 |title=ULA's Vulcan rocket launches private US moon lander, 1st since Apollo, and human remains in debut flight |url=https://www.space.com/ula-vulcan-centaur-first-launch-peregrine-celestis-moon-mission |access-date=2024-01-08 |website=Space.com |language=en}}</ref> The rocket, developed by [[United Launch Alliance]], uses the [[Blue Origin|Blue Origin's]] [[BE-4]] engine, though the second stage uses the hydrolox [[RL10]].
* [[New Glenn]] successfully reached orbit on its first try on 16 January 2025. The rocket and its engines are developed by Blue Origin. The first stage uses BE-4 engines, and the second stage uses the hydrolox [[BE-3U]].
* [[Terran 1]] had a failed orbital launch attempt on its maiden flight on 22 March 2023, and the development of the rocket was terminated. The rocket, developed by [[Relativity Space]], uses the [[Aeon 1]] engine.
* [[SpaceX Starship|Starship]] achieved a [[transatmospheric orbit]] on its [[IFT-3|third flight]] on 14 March 2024,<ref>{{cite web |title=Starship's Third Flight Test |url=https://www.spacex.com/launches/mission/?missionId=starship-flight-3 |access-date=2024-05-07 |website=SpaceX }}</ref> after two failed attempts. The rocket, developed by [[SpaceX]], uses the [[SpaceX Raptor|Raptor]] engine.
* [[Stoke Space Nova|Nova]] is being developed by [[Stoke Space]]. The first stage uses methalox Zenith engine, and the second stage uses a hydrolox engine.

[[SpaceX]] developed the [[Raptor (rocket engine family)|Raptor]] engine for its Starship super-heavy-lift launch vehicle.<ref name=fg20121120>{{cite web |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=2012-11-22 |website=FlightGlobal/Blogs Hyperbola |date=2012-11-20 |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. |url-status=dead |archive-date=2012-11-28 |archive-url=https://web.archive.org/web/20121128070948/http://www.flightglobal.com/blogs/hyperbola/2012/11/musk-goes-for-methane-burning.html }}</ref> It has been used in [[List of Starship launches|test flights]] since 2019. SpaceX had previously used only [[RP-1]]/LOX and hypergolics in their engines.

Blue Origin developed the BE-4 LOX/LNG engine for their [[New Glenn]] and the United Launch Alliance Vulcan Centaur. The BE-4 provides 2,400 kN (550,000 lbf) of thrust. Two flight engines had been delivered to ULA by mid 2023.

[[European Space Agency|ESA]] is developing a 980kN methalox [[Prometheus (rocket engine)|Prometheus rocket engine]] which was test fired in 2023.<ref name=NSF-2023>[https://www.nasaspaceflight.com/2023/06/themis-prometheus-hot-fire-test/#:~:text=Europe%20has%20just%20completed%20the,demonstrator%20on%20June%2022%2C%202023. ''Themis, Prometheus complete first hot-fire tests in France'']</ref>