ESA clarifies Prometheus engine tests are separate from Themis rocket delays

Engine Testing Update

ArianeGroup announced that a series of hot-fire tests for the latest Prometheus rocket engine were completed on October 29 at DLR's P5 test bench in Lampoldshausen. According to the company, these tests were carried out independently of preparations for the Themis reusable booster demonstrator. A primary goal of this late-October campaign was to validate a new combustion chamber produced through a Cold Gas Spray additive manufacturing process, which aims to reduce production time and costs.

Themis Flight Delays

Meanwhile, the inaugural flight of the Themis reusable booster remains significantly delayed. Although officials previously targeted early 2026 for the first hop test from the Esrange Space Centre in Sweden, the vehicle remains grounded as winter approaches. During an October press conference, ESA's Director of Space Transportation stated that operators would decide by late November whether a 2026 inaugural flight is still feasible before winter weather halts testing.