Europe has taken a crucial step towards a new era of spaceflight, an era in which rockets will not be single-use tools, but sophisticated vehicles capable of multiple missions. At the heart of this revolution is Themis, the prototype of the first European reusable rocket, whose epic journey from its assembly site in France to the launch pad in the far north of Sweden marked the beginning of a new phase in the European space program. This technology demonstrator, named after the Greek goddess of divine order and law, carries with it the hopes and ambitions of an entire continent in the race to reduce costs and increase access to space.

In mid-June, Themis left the integration facility in Les Mureaux, France, a place with a rich history where the main components of the powerful Ariane 5 rocket were once assembled. Now, this same space has served as the cradle for the future of European launches. Upon completion of its integration, the impressive 28-meter-tall demonstrator began its complex odyssey to the Esrange Space Center in Sweden, located deep within the Arctic Circle.

An extraordinary convoy through the heart of Europe

Transporting such a technological giant was no simple task. With a diameter of 3.5 meters and a height exceeding twice the length of a standard truck, Themis was an extraordinary load. Its journey, over 3000 kilometers long, took two weeks and led it through five European countries, combining road transport on a specially adapted truck and a voyage across the North Sea. Every kilometer of this journey was carefully planned to ensure the complete safety of the valuable cargo, a demonstrator that embodies the future of European space transportation.

The final destination was the Swedish Space Corporation (SSC) and their Esrange Space Center. There, Themis was welcomed into a brand-new integration building at the "Launch pad 3" launch complex. This infrastructure was built not only to receive the rocket but also to support the entire testing program, including fueling and operational procedures. Upon arrival at Esrange, teams from ArianeGroup, the prime contractor for the project, and SSC began detailed system checks to ensure that the transport had not caused any damage.

Preparations for the first jump

Before Themis can fly, a series of rigorous ground tests must be conducted. One of the first and most important steps will be the vertical installation of the landing legs. These crucial parts, which enable a soft and controlled landing, could not be transported while attached to the rocket's fuselage, so they were delivered separately and must now be precisely mounted. After that, the teams will integrate experimental payloads prepared by partners within the SALTO project, funded by the European Union through the Horizon Europe program, which is key to the realization of the first testing campaign.

The next phase involves a so-called "wet dress rehearsal". During this critical procedure, engineers will fill the rocket's tanks with liquid methane and liquid oxygen for the first time. This is an extremely delicate operation as it involves cryogenic fuels that must be kept at temperatures below –162 °C. The purpose of this test is to validate all fueling procedures and to check the behavior of the rocket's systems and ground equipment under real conditions, without igniting the engine.

The fiery baptism of the Prometheus engine

Once the fueling operations are mastered, the test that everyone is eagerly awaiting will follow – the static firing of the engine. At that moment, the heart of the Themis demonstrator, the revolutionary Prometheus engine, will come to life on the launch pad for the first time. During this test, known as a "hot-firing test", the complete countdown procedure for a real launch will be carried out. However, Themis will remain firmly secured to the ground and will not lift off. The powerful Prometheus engine will operate at low thrust, enough to validate the performance of the engine and the entire system under dynamic conditions.

Prometheus, named after the Greek titan who brought fire to humans, represents a technological breakthrough in itself. It is designed to be reusable and uses liquid methane as fuel instead of hydrogen, which brings significant advantages in terms of cost, ease of handling, and storage. This engine can vary its thrust from 30% to a short-term 110%, which is crucial for precise maneuvers during landing. The static firing test will also be crucial for validating the reconnection procedures that will be performed autonomously after landing by special forklift-sized robots responsible for connecting cables and pipes.

The first "hop test" and the future of European launches

After successfully completing the ground tests, Themis will be ready for its first "hop test" – a short flight with vertical takeoff and landing. The goal is not to reach a high altitude, but to demonstrate stabilized flight at a low altitude and, most importantly, the ability for autonomous vertical landing. The data and experience gathered during this short but critical maneuver will lay the foundation for progressively more advanced and higher test flights. These first flights will not take place before the end of 2025.

The Themis project is part of the European Space Agency's (ESA) preparatory program for future launch systems, with ArianeGroup as the prime contractor and with the participation of numerous industrial partners across Europe. The first flight campaign, realized within the SALTO project (Reusable Strategic Space Launcher Technologies & Operations), brings together a consortium of 25 partners from 12 EU member states, demonstrating the strength of pan-European cooperation. The ultimate goal is clear: to develop technologies that will provide Europe with its own reusable rockets, reduce dependence on other space powers, drastically cut launch costs, and strengthen competitiveness in the global market. Themis's journey has just begun, but its arrival at Esrange is already a historic moment that heralds an exciting future for Europe's access to space.