Europe's Prometheus reusable rocket engine is fired again on an upgraded test bench

6 November 2026

The European Space Agency has reported a fresh firing of Prometheus, its demonstrator for a low-cost reusable rocket engine, on an improved test bench. Prometheus burns liquid oxygen with liquid methane, a combination chosen because methane burns cleanly enough to allow an engine to be used again with less refurbishment, and because both propellants can be kept at similar temperatures. The engine is designed around heavy use of additive manufacturing and digital control so that the cost of a unit falls far below that of a conventional engine of the same class. It is meant to feed into Europe's next generation of launchers and reusable stage demonstrators. Test bench campaigns of this kind step the engine through ignition, throttling and restart so that each stage of its behaviour is measured before it is trusted with a flight.