On October 29, 2026, Prometheus completed several hot-fire tests at the P5 test bench in Lampoldshausen, Germany, the European Space Agency (ESA) reported. The campaign used P5’s new liquid-methane capability, tested a combustion chamber made with cold gas spray, and included repeated reignitions using engine inlet pressures without a high-pressure starter system. ESA published its account on November 6. ESA’s report describes ground tests of technologies intended for a reusable engine.
What the P5 campaign tested
ESA owns P5, the German Aerospace Center (DLR) operates the facility, and ArianeGroup is Prometheus’s prime contractor. The agency says Prometheus was the first engine fired at the upgraded stand using liquid oxygen and liquid methane.
Repeat reignition using engine inlet pressure is the standout ground-test result from the P5 campaign.
ESA says Prometheus reignited multiple times without a high-pressure starter system, and calls this a first in Europe for an engine of its class. The agency does not give an exact reignition count.
How the chamber was made
The campaign included a combustion chamber made using cold gas spray, an additive manufacturing process. Metal powder is sprayed at high speed onto the chamber body, where it bonds to the surface. ESA says additive methods can shorten production time, simplify the manufacture of complex components, and reduce costs.
What the upgraded P5 stand can do
The P5 upgrade added liquid-methane supply for engine tests. ESA says the facility can also be adapted to supply oxygen and hydrogen for future tests of liquid-hydrogen engines.
Prometheus is designed for in-flight restarts and reuse across multiple flights. The P5 campaign tested the engine on a ground stand; ESA’s stated flight and reuse capabilities are design aims.
Earlier Prometheus tests at Vernon
A separate 2023 campaign took place at ArianeGroup’s Vernon site with the Themis reusable-stage demonstrator. Actualidad Aeroespacial reported that the final test in the June 22 campaign lasted 12 seconds. A September 23 test completed the initial phase of the ESA contract, according to the publication. It also reported that a test on October 20 lasted 30 seconds and was followed by a reignition.
ESA’s next planned test campaign
ESA says the next campaign is planned to focus on Prometheus Mark 2, with initial tests at ArianeGroup’s Vernon test center in France.
