On 29 October 2026, the Prometheus reusable rocket engine completed several hot-fire tests at the P5 test bench in Lampoldshausen, Germany. Supported by the European Space Agency (ESA) through its Future Launchers Preparatory Programme and implemented by ArianeGroup as prime contractor, Prometheus is a reusable liquid oxygen and methane engine for future European launch systems. The P5 test bench is owned by ESA and operated by the German Aerospace Center DLR, and was upgraded to be able to supply methane fuel to test engines such as Prometheus. This Prometheus engine includes a combustion chamber made with new additive techniques. The tests have proven the upgraded test bench and new rocket engine production techniques work, expanding possibilities for European rocket engines.
“Repeated starting of engines and reduced manufacturing costs are key to expanding launcher supply and diversifying access to space for Europe,” said ESA’s Director for Space Transportation Geraldine Naja, “Prometheus has validated key technologies as well as inaugurated a test bench with new methane capability for more European engines to be tested and proven, thanks to the great work by all the teams involved in Germany and France.”
Prometheus is a low-cost reusable rocket engine, designed to be compatible with multiple reusable launcher stages and suitable for future European launch systems. The Prometheus engine allows for in-flight restarting and reuse on multiple flights. It has similar power to Europe’s largest rocket engine in use today, the Vulcain 2.1 used on Ariane 6. Prometheus uses liquid methane as fuel, reducing costs in engine and launcher design.
The tests included a new Prometheus combustion chamber manufactured using cold gas spray, an additive manufacturing process. In this process, metal powder is sprayed at high speed onto a combustion chamber body and bonds firmly to its surface. Additive manufacturing processes like these reduce production times, simplify manufacturing of complex components and decrease costs.
With these tests Prometheus also demonstrated it could reignite multiple times without a high-pressure starter system instead relying on engine inlet pressures – a first for an engine of this class in Europe.
The P5 test bench is one of the largest test facilities for cryogenic rocket propulsion in Europe. It was built as part of ESA’s Ariane 5 development programme, to test complete cryogenic propulsion systems and the P5 test bench has qualified the Vulcain engines used on Europe’s Ariane family of rockets, as well as the complete Ariane 6 upper stage.
The test bench was upgraded to operate with liquid methane, and Prometheus is the first engine to be fired up on the test bench running on liquid oxygen and liquid methane. The upgrade allows for quick adaptation back to supplying oxygen and hydrogen so P5 can continue to test liquid hydrogen engines in the future.
A next test campaign will focus on an improved version of Prometheus, known as ‘Mark 2’. Initial testing will be held at ArianeGroup’s Vernon test centre in France.
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