ArianeGroup said it has successfully completed a pivotal test campaign of its methane-fuelled Prometheus engine, executing four consecutive ignitions on 20 June at the company’s Vernon site in northern France. The results, announced on 2 July, verified the engine’s ability to restart multiple times in a single day, a requirement for Europe’s drive toward reusable launch systems. Developed under a European Space Agency contract, Prometheus is designed to generate about 100 tonnes of thrust while being manufactured at a fraction of the cost of current European engines thanks to extensive use of additive manufacturing. The engine will first power the Themis reusable stage demonstrator, with a static-fire test of the fully integrated vehicle scheduled at Sweden’s Esrange Space Centre ahead of a low-altitude hop planned before year-end. Beyond Themis, ArianeGroup intends to install four Prometheus engines on the two-stage Maia rocket being built by its subsidiary MaiaSpace, with an inaugural commercial flight targeted for the second half of 2026.