 Model of the Prometheus rocket engine, featured atIAC 2022. | |
| Country of origin | France European Union |
|---|---|
| Designer | ArianeGroup |
| Manufacturer | Ariane Group |
| AssociatedLV | Themis · Ariane Next · Maia |
| Liquid-fuel engine | |
| Propellant | LOX /CH4 |
| Cycle | Gas-generator |
| Performance | |
| Thrust, sea-level | 980 kN (220,000 lbf) |
| Throttle range | 30% to 110% |
| Chamberpressure | 100 bar (10,000 kPa) |
ThePrometheusrocket engine is an ongoingEuropean Space Agency (ESA) development effort begun in 2017 to create areusablemethane-fueledrocket engine for use on theThemis reusable rocket demonstrator,Ariane Next, the successor toAriane 6, possibly a version of Ariane 6 itself,[1] and theMaia reusable launch vehicle.[2]
Prometheus is abackronym from the original French project designation PROMETHEE, standing for "PrecursorReusableOxygenMethane costEffective propulsionSystem", and for the TitanPrometheus, from Greek mythology, creator of humanity, and god of fire, known for giving fire to humanity in defiance of the gods.
The engine is aimed to be reusable with substantially lower costs than traditional engines manufactured in Europe. The cost goal is to manufacture the Prometheus engine at one-tenth the cost of theAriane 5's first-stage engine.[3][4]
By 2020, the program was funded and is under development byArianeGroup.[4] By 2025, the engine had completed two successful test firing campaigns including four successive ignitions in a single day.[5]
The engine is planned to have the following features:
TheEuropean Space Agency (ESA) began funding Prometheus engine development in June 2017 with€85 million provided through theFuture Launchers Preparatory Programme, 63% of which came fromFrance.[1]
By June 2017, Patrick Bonguet, lead of theAriane 6 launch vehicle program atArianespace, indicated that it was possible the Prometheus engine could find a use on a future version of theexpendable Ariane 6 launcher. In this scenario, a "streamlined version ofVulcain rocket engine called Vulcain 2.1 would have the same performance as Vulcain 2". The expendable Ariane 6 was then expected to make aninitial launch in 2020.[3]
By June 2020, the ESA was on board with this plan and had agreed to completely fund the development of the Prometheus precursor engine to bring the "engine design to a technical maturity suitable for industry". The objective of the overall program as stated in June 2020 was to utilize Prometheus technology to eventually "lower the cost of production by a factor of ten of the current main stageAriane 5Vulcain 2 engine".[4] In 2021, ESA invested an additional €135 million in the project,[8] including €30 million from DLR.[9]
The engine was started up in Nov 2022. It had a successful 12 second test firing in June 2023, at the THEMIS test stand inVernon, France.[10] An additional successful hot fire test was reported at the end of 2024.[11] The second test campaign for Prometheus in Vernon finished in June 2025 after a second model of the engine performed a series of repeated hot-firing tests under various thrust profiles. On 20 June 2025, the engine successfully demonstrated 4 consecutive ignitions, a first in Europe for this type of engine. A third model of Prometheus will be tested atDLR'sLampoldshausen test site.[5][12]
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