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Following the Ariane 6’s development flight, Arianespace plans to make its first commercial flight by year-end.
When most attendees at the Ariane 6’s July 9 inaugural launch broadcast at the European Space Agency’s headquarters in Paris left the conference hall to celebrate, they did so with good reason.
Most of the payloads had been placed into orbit successfully, at 600 km (370 mi.). The ArianeGroup Vinci engine had proven it could reignite, showing the upper stage’s ability to deliver spacecraft on more than one orbit. The auxiliary propulsion unit (APU), a crucial component for mission flexibility, had powered up for a second time.
- The first Ariane 6 places payloads into orbit
- Technology demonstration falls short of success
But while guests and hosts in Paris were enjoying the evening, an unexpected issue emerged. The APU had shut down for a reason engineers have yet to find, and the end of the flight did not take place as expected. The Ariane 6’s upper stage could not deorbit.
That sequence of events means that Europe is back in space but needs to do more work to take full advantage of the new launch vehicle’s potential.
The Ariane 6’s liftoff from the European Space Agency (ESA) spaceport in Kourou, French Guiana, was a decade in the making, as efforts to replace the long-serving Ariane 5 suffered delays. ESA lost some of its missions to archrival SpaceX, including one for the EU’s Galileo positioning system.
The market has changed since the Ariane 6 program began in 2014. European officials have long emphasized the goal of a 40% cost cut compared with the Ariane 5 in order to compete with SpaceX’s Falcon 9. Sovereignty concerns, however, gradually emerged as the top priority. For instance, the EU increasingly sees cooperation from the White House as less reliable in the long term, especially since the Trump presidency and with the prospect of a second Trump term.
Meanwhile, demand for commercial space launches has grown to unprecedented levels and is expected to remain high for years to come. SpaceX is enjoying a hegemonic market position with Falcon 9 prices on an upward trend. Commercial space launch customers are even more eager to see the Ariane 6 succeed, as they want to rely on several launch options.
In that context, the Ariane 6’s versatile and adaptable design is relevant. In a single mission, the vehicle can deliver payloads to both low Earth and geostationary orbits.
Early sales show the Ariane 6’s capabilities suit the market. Launch service provider Arianespace’s backlog totals 29 missions, with both institutional and commercial customers.
In a few years, the Ariane 6 program will be called a success if launches take place on time and payloads are reliably placed into orbit. The fact that the 40% cost-cut objective has yet to be met—and may still not be enough to compete with the Falcon 9’s improved versions—will be a secondary consideration.
Arianespace can confidently plan out the launch vehicle’s first missions. They will be relatively straightforward, with limited use—if any—of the Vinci’s ability to reignite. The Ariane 6’s December schedule calls for one launch, military observation satellite CSO-3 for the French government. Arianespace will operate the commercial flight, taking over from ESA, which operated the development flight on July 9.
Other missions may be more complex. The Vinci was designed to meet that need, and the inaugural flight centered on related evaluations. On July 9, the first Vinci boost sent the upper stage into an elliptical orbit. The second one circularized the orbit. During a technology demonstration phase, a second reignition and two additional APU power-ups were to follow payload separation, demonstrating the potential to perform a sophisticated mission.
The Ariane 6’s new APU plays a critical role in Vinci engine burns. The component pressurizes propellants and uses a force of 200-300 Newtons (45-67 lb. thrust) to squeeze liquid hydrogen and oxygen near the bottom of their tanks, close to the engine propellant intake. The APU also can fine-tune the injection trajectory after each Vinci boost.
After its second power-up, the APU ran for an unspecified time in microgravity, then stopped earlier than planned, with a visible trajectory deviation.
A third Vinci boost was supposed to help deorbit the Ariane 6’s upper stage and send two reentry test capsules into the atmosphere, but that did not happen. Because the APU would not power up again, the Vinci could not reignite, making deorbit impossible, prime contractor ArianeGroup CEO Martin Sion explained.
As planned, the Ariane 6’s upper stage was passivated and emptied of its propellants at about 580 km. The two capsules were not released to prevent additional debris.
One or two weeks should be enough time to analyze why the APU behaved as it did, said Valerie de Korver, Ariane 6 system test program manager at ArianeGroup. Upper-stage deorbiting is a strong point for the Ariane 6. To ensure deorbiting, as well as the multiorbit delivery capability, engineers will have to delve into the APU design. Testing will be a challenge, as some trials can only be done in microgravity.
Alongside the renewed work on the APU, Europe is shifting its focus to ramping up production. ESA, ArianeGroup, Arianespace and French space agency CNES—which is in charge of the Kourou spaceport—have set an ambitious target of 10-12 launches per year beginning in 2027, starting with six next year.
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