Themis nears first flight. The rocket's return manoeuvre is being built in Gdynia

Europe's reusable rocket stage is meant to come back to earth after separation and land vertically. To do that, it first has to turn around. The system responsible for that manoeuvre is being developed by a company in Gdynia, on the Polish Baltic coast.

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03 august 2026   |   00:06   |   Source: Gazeta Morska   |   Prepared by: Michał Iwański   |   Print

fot. SpaceForest

On 23 July 2026, at the Esrange space centre in northern Sweden, teams from ArianeGroup and SSC Space carried out a Wet Dress Rehearsal of the Themis demonstrator. It was the most significant publicly announced milestone in the test campaign since September 2025, and a signal that Europe is moving closer to the first flight of a reusable stage of its own.

What the rehearsal involved

A Wet Dress Rehearsal is a full simulation of pre-launch procedures without engine ignition. The teams ran through the countdown sequence, mission termination procedures and the operations planned for after a future flight and recovery of the vehicle.

The demanding element was filling the 28-metre demonstrator with liquid nitrogen chilled to around minus 200 degrees Celsius, to verify tanks, lines and other components under cryogenic conditions and high pressure. Themis will ultimately run on liquid oxygen and liquid methane, but nitrogen reproduces the same thermal conditions at a comparable density without being flammable. That is standard practice for early ground testing.

The rehearsal also produced data on anomalies to be resolved before the next stages. The campaign's next objective is the demonstrator's first flight, a short hop at low altitude that will test the stage's behaviour at lift-off, in flight and during a controlled return. No date has been given, as ArianeGroup is still analysing the July data.

The Polish contribution: turning before landing

At the heart of Themis is the Prometheus engine developed by ArianeGroup. But the main engine alone will not bring a stage back to its landing pad. After separation the vehicle continues on a ballistic trajectory, still nose-forward, and has to rotate through 180 degrees before firing its engine to brake. That manoeuvre is known as the flip.

The system that will perform it is the responsibility of SpaceForest, based in Gdynia. The GFCS subsystem, or Green Flip Control System, is an auxiliary rocket motor commanded through a link to the Themis stage's onboard computer. The name is not marketing: the system runs on green propellants, the same ones used by the main engine of Perun, the suborbital rocket the company builds itself.

It is not the only Polish input. Engineers at Sener Polska are designing and building the GFAM mechanism, which locks and unlocks the grid fins once deployed. The fins steer the vehicle during descent, so both Polish subsystems fall within the same, most demanding phase of the mission: the return.

Themis is a European Space Agency programme led by ArianeGroup, supported by the European Union through the SALTO project funded under Horizon Europe. The consortium comprises 25 partners from twelve countries. SpaceForest is one of the few SMEs among them, alongside groups such as Avio, Thales Alenia Space and Safran.

Why this is a maritime story

The Baltic connection is not a figure of speech. All three test flights of the Perun rocket to date have been conducted from the Central Air Force Training Ground at Ustka, the only site in Poland where launching a suborbital rocket is practicable. The reason is straightforward: the drop zone falls over the sea, and the rocket descends by parachute into the water.

On the third flight, on 22 November 2025, Perun reached roughly 20 kilometres in about 60 seconds, at an average speed of around 330 metres per second. The whole flight lasted 277.2 seconds and covered lift-off, ascent, the ballistic phase, descent and landing. The company highlighted a detail at the time that says more about Polish infrastructure than the flight parameters do: the operation ran within a launch window between 13:00 and 14:00, while preparations took over seven hours. With a permanent launch base in the country, that time could be cut substantially.

The constraint has measurable consequences. SpaceForest plans three Perun flights in 2026, but only one from Poland, from Ustka. The other two are to be conducted from the Azores, where the Atlantic Spaceport Consortium is building a European spaceport on Santa Maria, and from an offshore platform in the North Sea off the Danish coast, in cooperation with EuroSpaceport.

The last of these is the most interesting from a maritime standpoint. It will be the first time a Polish company demonstrates a vertical launch from a floating platform. Sea-based launches are gaining ground across the sector because they allow azimuth and safety zones to be selected independently of land geography, while placing an entirely different set of demands on the teams involved: platform stabilisation, operations in a seaway, and supply logistics.

A rocket built to come back

Perun is a reusable suborbital rocket 11.5 metres long and 45 centimetres in diameter, powered by the hybrid SF-1000 motor, which uses nitrous oxide as oxidiser and paraffin as solid fuel. It is designed to carry payloads of up to 50 kilograms to an altitude of 150 kilometres, providing around five minutes of microgravity for experiments.

The flights are being conducted under the Boost! contract with the European Space Agency, covering four suborbital launches by the end of 2026, at successive altitudes of 50, 80, 100 and 150 kilometres. The fourth flight from Ustka has been in preparation since spring, and the company reported that a software fault which surfaced during the previous mission had been eliminated and verified in a virtual environment.

The overlap between the two programmes is deliberate. Knowledge and technology from Perun, including green propellants and hands-on experience with vehicle recovery, feed directly into the system being built for Themis. For a company of this size that is an unusual route: rather than supplying components for other people's rockets, SpaceForest builds its own and uses that as its entry into a European flagship programme.

What is at stake

Reusability is now the principal measure of competitiveness in the launch market. SpaceX established its lead by flying Falcon 9 first stages repeatedly. Europe operates Ariane 6 and Vega-C, neither of which was designed with recovery in mind, and it is precisely that gap Themis is meant to address.

An operational system remains some way off. But in a campaign that will determine whether Europe learns to recover rocket stages, one of the critical elements is being built in Gdynia, and the rocket on which those technologies were trialled first lifts off from a range on the Polish coast.

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SpaceForest Themis manewr FLIP polska firma w projekcie SALTO rakieta Perun start z Ustki europejska rakieta wielokrotnego użytku demonstrator Themis test Esrange

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