An emotional countdown to the maiden launch of the Ariane 64, Europe’s most powerful rocket

In a tightly controlled manufacturing hangar west of Paris, workers put the finishing touches on an enormous silver-colored engine. In just a few days, a similar machine will help propel the most powerful version of Europe’s Ariane 6 rocket yet, flying for the first time with four boosters.

On Thursday, the Ariane 64 rocket — named after its four boosters — is scheduled to make its maiden launch from the European spaceport in Kourou, French Guiana. The mission will deploy 32 satellites for Amazon Leo’s broadband constellation, a direct competitor to SpaceX’s Starlink network.

The flagship of Europe’s rocket industry is racing in a highly competitive global environment dominated by Elon Musk’s SpaceX. At ArianeGroup’s plant in Vernon, engineers design, integrate and test engines for the European heavy-lift launcher, while at another site west of Paris, in Les Mureaux, the rocket’s main stage components undergo careful assembly.

“It’s a special launch — something new for us on Ariane 6,” explains ArianeGroup Chief Technical Officer Hervé Gilibert. This flight marks the debut of the four-booster configuration, making the rocket roughly twice as powerful as the version that has been flying since early 2024.

“Don’t be surprised if you see it accelerate much more than Ariane 62, the version we have already launched five times,” Gilibert notes. “It delivers significantly more power, allowing much heavier payloads to be sent into space.”

The Ariane 6 program represents a collaborative effort across Europe, with 13 nations from the European Space Agency financing and cooperating on its development. Components are manufactured throughout the continent before coming together at two main integration sites.

“We are working with more than 600 subcontractors,” says Gilibert. “Everything comes together at two main sites — Bremen in Germany for the upper stage, and Les Mureaux in France for the lower, or main stage of the launcher.”

For Thursday’s launch, all components have completed their trans-Atlantic journey to French Guiana for final assembly. The fully integrated rocket stands about 62 meters tall, comparable to a 20-story building.

The mission will last approximately one hour and 50 minutes—nearly a full orbit around Earth—before the Amazon Leo satellites are deployed in pairs. These satellites represent Amazon’s entry into the satellite internet market currently dominated by SpaceX’s Starlink constellation.

The launch sequence begins with the ignition of the Vulcain 2.1 engine built at the Vernon facility. “For a few seconds, we verify that it is functioning properly,” explains Emmanuel Viallon, director of the Vernon site. “Once we are fully confident it will operate correctly for the eight minutes that follow, we ignite the solid boosters and the rocket lifts off.”

Those four boosters provide massive thrust at launch, consuming 142,000 kilograms of solid propellant in just over two minutes before burning out. According to Viallon, Ariane 6 was designed with cost efficiency in mind, aiming to halve operating expenses compared to its predecessor, Ariane 5, which concluded its program in 2023 after decades of service.

At the Vernon facility, engines undergo rigorous testing under near-real launch conditions. Deep within the surrounding forest, reinforced structures hold engines in place as they fire at full power, with test teams operating from underground control rooms for safety.

“When an engine arrives here, those are really important moments for the team,” says Laurence, the engine firing test director. “And then, seeing that the launch goes well… that brings a great deal of gratification.”

Meanwhile at the Les Mureaux facility, engineers are already preparing components for upcoming missions. Huge white cylinders form the rocket’s 5.4-meter-wide main stage, including tanks for supercooled hydrogen and oxygen that will feed the Vulcain engine.

Caroline Arnoux, business unit director at ArianeGroup, confirms that seven to eight launches are planned for this year. “We have a very strong order book, equivalent to about 30 launches,” she says. “Roughly one-third are institutional missions and two-thirds commercial. And our commercial customers are all waiting for the Ariane 64 version, which will be extremely important in the coming years.”

Hermann Ludwig Moeller, director of the European Space Policy Institute, notes that the Ariane 64 “is an additional level of performance” and represents “an important step in the whole program, hoping to demonstrate that this configuration works as reliably as Ariane 6 has been working so far.”

While Moeller acknowledges that comparisons with SpaceX are difficult due to different business models—SpaceX “builds the rockets, builds the satellites and also sells the service”—Europe operates with separate companies responsible for different aspects of space operations.

For Ariane 6, diversifying its European customer base remains a key challenge, potentially through systems of European preference for government missions and further commercial market development.

Arnaud Demay, the Ariane 6 project manager, emphasizes that independent access to space remains the core objective of the program, allowing “Europe to meet its own needs.” ArianeGroup is also looking to the future, working on technologies to enable component reuse and potentially even entire stage recovery—a direct response to SpaceX’s reusability advantages.

For those dedicated to Europe’s space program, each launch represents the culmination of years of work. As Demay confides, he almost always finds himself overcome with emotion when watching a rocket lift off: “We do it so rarely, and it’s so majestic when it takes off: that little touch of magic inevitably overwhelms me every time.”