Themis horizontal

Europe’s first reusable rocket main stage demonstrator – Themis – at its ArianeGroup integration hall in Les Mureaux, France, June 2025.

Themis encompasses all the elements for a reusable rocket stage. The Themis programme includes developing the flight test model that requires new technologies from European countries such as the vehicle landing legs, grid-fin aerodynamic stabilisers, light-weight fuel tanks, distributed power systems, avionics and reduced-diameter multi-engine bay.  New flight algorithms, derived from previous European projects, will be key to make Themis land safely after flight.

The first Themis flights will be from Europe’s launch centre, Esrange, in the north of Sweden. The first flight will be a small “hop”, where the engine will fire continuously but at varying ‘throttles’ – this in itself will be a first for Europe with the use of cryogenic propulsion. Flying up to 100 m on its first trip towards space, the hop-test is a significant milestone and allows engineers to focus on the critical landing and ground sequences for such a rocket.

Themis will have a busy landing, as the mission designers want to recover any excess fuel in the light-weight stainless steel tanks as quickly as possible after touchdown to avoid any possible incident that could damage the landing pad.

Themis was developed as a European Space Agency future launchers preparatory programme with ArianeGroup as prime contractor and multiple European industrial partners. Themis’s first flight campaign is being funded by the European Commission’s Horizon Europe project Salto.