220,000 lbs of thrust: Methane-fueled reusable rocket engine clears ground tests

The European Space Agency’s (ESA) reusable Prometheus rocket engine, which can produce about 220,000 lbs of thrust (100 metric tons-force), has just completed a series of ground tests for future space missions. France-based aerospace firm ArianeGroup built the methane-oxygen engine, which was tested on Thursday, October 29, 2026. The ground trials took place at the German Aerospace Center’s (DLR) upgraded P5 test site in Lampoldshausen. During the campaign, Prometheus was ignited multiple times in a single day and reached stable operating conditions after each ignition. It also proved it could start without a separate starter system. This, as per ArianeGroup, was a European first for a gas-generator-cycle engine in its thrust class. “Reusability is more important than ever in space transportation,” Philippe Clar, head of Space Transportation Programs at ArianeGroup, pointed out. The tests also included a combustion chamber produced using a new 3D-printing process. Multiple successful ignitions According to DLR, the latest campaign marked a first for its P5 facility, which had never previously achieved repeated methane-oxygen engine ignitions in a single test day. The upgraded site can now handle not only up to five ignitions per day but also longer engine burns and different thrust levels. Anja Frank, head of the DLR Institute of Space Propulsion, emphasized the significance of the achievement. “Up to five ignitions in a single test day place high demands on the coordination of the test stand systems,” Frank said. “The fact that we can carry out these procedures automatically, safely and in a reproducible manner is an important step towards testing reusable propulsion systems.” Prometheus fires during a hot-fire test at DLR’s P5 test stand in Germany. Image credit: ArianeGroup These capabilities are crucial for reusable rockets, which may need to restart their engines after launch to return to Earth and carry out controlled landings. At the same time, the P5 facility was upgraded to accommodate liquid methane and liquid oxygen, the two propellants Prometheus uses. It can also measure thrust, fuel flow, pressure, and temperature, and provide data to improve the rocket engine. “With the modernized P5, we can test high-thrust methane-fueled rocket engines reliably and comprehensively,” Frank added. A 3D combustion chamber Meanwhile, the team also conducted the first test of a combustion chamber made with Cold Gas Spray (CGS), a 3D-printing process. The process involves spraying metal powder at high speed onto a part, where the particles bond to its surface to form solid layers without melting. ArianeGroup, which is developing Prometheus on behalf of ESA, makes extensive use of 3D printing to simplify manufacturing, shorten production times, and cut the costs. “The success of these new tests on the Prometheus reusable rocket engine is a key step forward for ArianeGroup and for Europe,” Clar said in a press release. The modernized P5 test stand expands the testing capabilities for Prometheus. Image credit: DLR (CC BY-NC-ND 3.0) The engine also features adjustable thrust, which is essential for reusable rockets. While launches require high thrust, returning rocket stages need precise control during descent and landing. It runs on liquid methane instead of liquid hydrogen, as methane is denser and can be stored at higher temperatures. Clar highlighted the role of cooperation in designing reusable rockets. “This new campaign demonstrates the ability of our teams in France and Germany, working with our partners, to develop solutions that meet market needs and break new ground, to give Europe sovereign capabilities in reusable space technologies,” he concluded. In the meantime, ArianeGroup has already begun work on an upgraded engine, dubbed the Prometheus Mark 2. Its next test campaign will reportedly take place at the company’s Vernon test center in France. Get the latest in engineering, tech, space & science - delivered daily to your inbox.Based in Skopje, North Macedonia. Her work has appeared in Daily Mail, Mirror, Daily Star, Yahoo, NationalWorld, Newsweek, Press Gazette and others. She covers stories on batteries, wind energy, sustainable shipping and new discoveries. When she's not chasing the next big science story, she's traveling, exploring new cultures, or enjoying good food with even better wine.