ESA Tests Themis Rocket Prototype in Second Rehearsal
The European Space Agency's Themis demonstrator completed a second wet dress rehearsal at the Esrange Space Center in Sweden on 29 September.
Updated on Nov. 4, 2026 in Space
The European Space Agency completed a second wet dress rehearsal of its Themis rocket prototype on 29 September, following a first rehearsal in July. The exercise allowed teams from SSC Space and ArianeGroup to practice operations with the demonstrator on the launch pad.
Why it matters
Themis is a flagship European demonstrator for low-cost rocket recovery and reuse technologies, and the rehearsals test the full system before any launch attempt. Practicing countdown procedures with the rocket on the pad helps operators identify problems in advance.
The rocket prototype was filled with liquid nitrogen cooled to -200°C during the wet dress rehearsal to test the whole system under extreme cold and high pressure. The extraction does not report the outcome of the test or the planned date of the first flight.
The players
European Space Agency
The European Space Agency is an intergovernmental organization that leads Europe's civil space programs, including the development of the Themis demonstrator.
ArianeGroup
ArianeGroup is the European aerospace company that builds the Ariane rocket family and participated in the Themis rehearsals.
SSC Space
SSC Space is a Swedish space services company that operates the Esrange Space Center, where Themis is on the launch pad.
The details
Themis is powered by the reusable liquid oxygen and methane-fuelled engine Prometheus and sits on the launch pad at the Esrange Space Center in Sweden, which is operated by SSC Space. Teams from SSC Space and ArianeGroup used the rehearsal to practice countdown procedures on the pad.
Timeline
July: First wet dress rehearsal of Themis held
29 September: Second wet dress rehearsal of Themis completed
Roadmap
Themis is a European demonstrator for low-cost rocket recovery and reuse, a technology path that departs from the expendable-rocket model of the Ariane family. The rehearsals move that prototype closer to flight testing in Europe's broader effort to reduce launch costs.
Reusable launch technology like Themis could eventually lower the cost of putting satellites and scientific payloads into orbit. Lower launch costs would affect what missions are financially feasible for research and commercial users.
The takeaway
Reusable rocket demonstrators like Themis show how ground testing under extreme conditions precedes any flight attempt. Rehearsals of this kind expose operational issues before a launch vehicle leaves the pad.
Further reading
Explore more in the Space section for context on Europe's launch programs.
