Themis: the journey of Europe’s first reusable rocket has begun

In brief

• Europe’s first reuseable rocket demonstrator Themis has arrived at its launch zone in Esrange Space Centre, Sweden.
• The transfer from Les Mureaux, France, took two weeks and covered five countries.
• Themis will now be prepared for a ground test campaign with its landing legs added. 
• The first flight will be a short hop reaching 20 m altitude.

In-depth

Europe’s first reuseable rocket demonstrator left its integration building in Les Mureaux, France on 12 June and is now at its launch pad at Esrange Space Centre in Sweden.

Themis is an ESA rocket prototype – a European demonstrator for low-cost rocket recovery and reuse technologies, designed to launch, land vertically and live on for another mission.

The 28-m tall rocket stage was assembled since 2023 at the former Ariane 5 main stage integration building in Les Mureaux, France. Themis completed a vehicle ‘fit-check’ in December 2024, proving that its main elements fit together as planned and confirming the mechanical connections and interfaces connect smoothly.

Since then, ArianeGroup and ESA teams have completed the integration of avionics and additional systems to be tested in flight, while also preparing Themis for its journey across Europe.

Exceptional convoy

The 3.5 m diameter cylinder was loaded onto a tailored truck and made its way to the northern region of Sweden, north of the polar circle, on roads and navigating the North Sea.

With Themis being a metre wider and over twice as long as a standard European road truck, the voyage took two weeks, covering over 3000 km and passing through five countries.

The hop test-campaign for Themis will first take place at Swedish Space Corporation’s Esrange Space Centre facility in Sweden in the scope of Horizon Europe project Salto, just as a car wouldn’t get far without a compatible fuel or charging station, an infrastructure has been built to support Themis work, fuelling and operations. The Esrange Space Centre  “Launch pad 3” welcomed Themis in a new integration building where the rocket systems will be checked after transport and its systems prepared. Then, the landing legs will be attached vertically on the launch pad as they cannot travel in place over land and have been shipped separately.

Getting ready for liftoff

On the launch pad, ArianeGroup and Swedish Space Corporation engineers will conduct a ‘wet dress rehearsal’, validating the liquid methane and liquid oxygen propellants Themis uses. This delicate operation involves filling the tanks with methane in liquid form that flows at cryogenic conditions below –162 °C. 

Once these operations are mastered, the next step will be a hot-firing test, whereby Themis’s Prometheus engine is fired up without take-off. This test requires the propellant tanks to be refilled and involves a full launch countdown, but Themis will remain secured to the ground and will not lift off, as the powerful Prometheus engine will fire at low thrust

This critical step will validate the ground reconnection procedures conducted by a handful of different forklift-sized Themis helper robots that will disconnect cables before launch and reconnect them autonomously after landing. 

A first hop for Themis…

Themis, the first European reusable main stage’s full-scale demonstrator, has been developed by ESA’s future Space Transportation preparation programme, with ArianeGroup as prime contractor and multiple European industrial partners. Themis’s first flight campaign will be realised in the scope of Horizon Europe project Salto, funded by the European Union. The Salto project is responding to the EU Space Research and Innovation (R&I) Programme and implemented by the European Commission under direct management. 

Source : ESA

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