European Reusable Rocket Demonstrator Themis Completes Wet Dress Rehearsal Test

On July 23, 2026, the European demonstrator, Themis, successfully completed a wet dress rehearsal at the Esrange Space Center in northern Sweden. This test allowed teams from ArianeGroup and SSC Space (the company managing the Esrange spaceport) to simulate the full day's operational sequence planned for the future Hop Test, the demonstrator's first vertical takeoff and landing flight.

During the test, Themis's propellants, liquid methane and oxygen, were not used. Instead, liquid nitrogen was loaded into the tanks and cryogenic lines, replicating the temperature and pressure conditions the system will face during actual operations. Temperatures reached approximately -200 °C during the trial.

The simulation involved both Themis and the infrastructure built at Esrange to support its operations. The test included the preparation of the vehicle and pad, a virtual countdown, and the safety procedures that will be necessary after stage recovery.

The WDR test represents one of the main milestones in the testing campaign that began after Themis arrived at Esrange in June 2025. The demonstrator was subsequently installed on the pad to commence combined tests, focusing on the joint verification of the vehicle's systems and ground infrastructure. The data collected on July 23 will now be analyzed to continue the campaign. ArianeGroup and SSC Space have not yet announced a timeframe for the next test.

The First European Reusable Rocket?

In the planned sequence for Themis, following the wet dress rehearsal, a static fire of the Prometheus engine is scheduled. During this test, the engine will be ignited while the vehicle remains tethered to the ground. This trial will serve to verify the propulsion, ground systems, and operational procedures together before proceeding to the actual flight.

The next objective will be the Hop Test: a low-altitude flight during which Themis will perform a vertical takeoff, execute planned maneuvers, and land back in the launch area. The campaign is being conducted as part of the SALTO project, funded by the European Union and coordinated by ArianeGroup, involving 25 partners from 12 countries. The program is not solely focused on the first Hop Test but aims to develop and validate the technologies and procedures necessary for future reusable launch systems.

Esrange plays a central role in this campaign. SSC Space has developed and manages the necessary infrastructure for Themis's integration, refueling, control, and testing, enabling the joint experimentation of the vehicle and the ground segment required for recovery operations.

However, Themis will not become a fully operational reusable rocket but will serve solely as a technological demonstrator developed to gather data on propulsion, flight control, recovery, and reuse of a stage.