Fit-check timelapse: Themis reusable rocket stage demonstrator

In December 2024 the first Themis – Europe’s demonstrator of a reusable rocket first stage – completed a ‘full fit-check’ standing tall at ArianeGroup’s facility in Les Mureaux, France.

This step in the rocket development proves that all main elements fit together as planned, confirming the mechanical connections and interfaces from the lower to the upper parts of the rocket stage connect smoothly and as intended.

The 28-m tall model includes the main elements for Themis such as the engine bay, the fuel tanks, the flight control bay and the upper part. It is powered by the new-generation European Prometheus, an engine developed by ArianeGroup that runs on liquid methane and liquid oxygen and can vary its throttle in flight that is necessary for landing.

This fit-check was one of the key requirements and one of the final steps in Les Mureaux to conclude the development phase of Themis – designated T1H for Themis 1-engine Hop – opening the way for its transport to the Esrange Space Center in Sweden from where it will have its first flight next year. Its first flight will be a short hop, taking off and landing from the same location, organised as part of the European Commission Salto programme.