Scenes from a 30-second burn with re-ignition of an early prototype of the Prometheus engine at ArianeGroup’s test facility in Vernon, France, on 20 October 2023.

The 100-tonne thrust class Prometheus burns liquid oxygen-liquid methane fuel. Methane is clean burning and simplifies handling, to help enable reusability and reduce the cost of ground operations before and after flight.

The engine is mounted in an early prototype of a reusable rocket stage, called Themis, which is being developed in parallel with the engine under contract from ESA. While engine testing continues, work is also underway to prepare a more advanced Themis prototype for a series of “hop-tests” in Kiruna, Sweden. The objective will be to lift off and rise to as high as 100 m, to check flight and landing capability.