Themis Rocket Completes Second Ground Rehearsal
The European Space Agency's reusable-launch prototype is still at the test stage, with no flight date given in the source.
Updated on Nov. 4, 2026 in Space
The European Space Agency completed a second wet dress rehearsal of Themis, a rocket prototype sitting on the launch pad at the Esrange Space Center in Sweden, on 29 September. The research-stage demonstrator is not a flying vehicle; the rehearsal tested ground procedures and the full system under extreme cold and pressure.
Why it matters
Themis is a flagship European demonstrator for low-cost rocket recovery and reuse, and the rehearsals are a step toward validating those technologies before any flight. The second rehearsal followed a first in July, giving operators and ArianeGroup engineers repeated practice with countdown procedures.
The rehearsal filled the prototype with liquid nitrogen cooled to -200°C, a test of the whole system under extreme cold and highly pressurised conditions. The source reports no performance figures for the Prometheus engine or the vehicle itself.
The players
European Space Agency (ESA)
Europe's national-space-agency-style coordinator that funds and directs the Themis demonstrator for low-cost rocket recovery and reuse.
ArianeGroup
The European aerospace company that builds the Ariane family of launch vehicles and worked alongside SSC Space engineers on the rehearsals.
SSC Space
The company that operates the Esrange Space Center in Sweden, where the Themis prototype is on the launch pad.
The details
A wet dress rehearsal is a ground test in which a rocket is loaded with its cryogenic propellant to run through the launch sequence without lifting off. In this case the team filled the prototype with liquid nitrogen cooled to -200°C, a stand-in for the super-cold fuel and oxidiser a real flight would carry, to check how the whole system handles the cold and pressure. Prometheus, the reusable engine that powers Themis, burns liquid oxygen and methane, and the rehearsals let SSC Space and ArianeGroup teams practise countdown procedures at the Esrange launch facility.
Timeline
July: first wet dress rehearsal held at the Esrange Space Center.
29 September: second wet dress rehearsal completed on the launch pad.
The Tech Race
Themis is positioned as a European effort to develop low-cost rocket recovery and reuse, a capability the source does not compare to any named competitor program. Its progress is measured here only against its own earlier July rehearsal.
The rehearsals are ground tests, so they do not change anything for users of launch or satellite services today. Availability, timelines, and any flight date for Themis are not stated in the source.
The takeaway
Watch for the outcome of the Themis test campaign, including whether ESA announces a flight date for the prototype. The next verifiable milestone is any formal report or launch schedule that follows these rehearsals.
Further reading
For the wider field of reusable launch vehicles, see our Space coverage.
