WASHINGTON — The European Space Agency began funding a reusable rocket engine anticipated to be ready for a test-fire demonstration in 2020, the same year as the first launch of the future Ariane 6 rocket.

ESA and Airbus Safran Launchers, the 50-50 joint venture between Airbus and Safran that is rebranding as ArianeGroup, signed a contract to develop Prometheus, a liquid- oxygen-and-methane-fueled engine that would cost 1 million euros ($1.1 million) per copy, or a tenth of what Ariane 5’s Vulcain 2 first-stage engine costs to produce. ArianeGroup is working on Prometheus in parallel with development of Ariane 6, which will initially rely on the expendable Vulcain 2.1 engine.

Prometheus, which started out as a small, joint research initiative between the French space agency CNES and Airbus Safran Launchers, was adopted by ESA in December. ESA foresees the engine entering service around 2030 on future European launch vehicles, not necessarily Ariane 6.

“This signing underlines our determination to prepare now for the future of Europe’s launchers beyond 2030, while pulling out all the stops to ensure an Ariane 6 first flight in 2020,” Alain Charmeau, CEO of ArianeGroup, said in a June 22 statement. “Those two approaches based on continuous competitiveness and innovations are perfectly complementary.”

ESA allocated more than 80 million euros to Prometheus at its December 2016 ministerial conference. The agency did not disclose how much of that money it released with the signing of today’s contract.

Now that it’s an ESA program, Prometheus will see additional industrial partners join ArianeGroup in developing the engine. New partners include Italy-based Avio, manufacturer of the Vega rocket; GKN, a Swedish supplier for Ariane 5 and Ariane 6 components; and Safran’ Belgian subsidiary Safran AeroBooster. The companies intend to leverage new manufacturing methods such as 3D printing, predictive maintenance and digital control, and to test the engine at the German space agency DLR’s Lampoldhausen engine test facility.