Ariane 6: How to build a space rocket step-by-step

A week may be a long time in politics — for some, a day is quite enough — but in rocket science, not even a single year would get you passed the first post.

It took Ariane 6, Europe's flagship heavy-lift rocket, two full years just to get a green-light to be developed. And it took another eight years being built before its inaugural flight in 2024.

Building a whole new rocket system takes more than just creating a new rocket that shoots satellites into space.

A rocket system not only includes the rocket, often in various constellations, but also its engines, the fuel — which in Ariane 6's case is a new concoction of liquid oxygen and liquid hydrogen — a dedicated launchpad and a manufacturing network to create it all.

Throw a global pandemic into the mix and 10 years is nothing. Here's how Ariane 6's decade in development evolved.

Ariane 6 Timeline: 2014-2016

It all started in 201, with a proposal from European industry: They said they wanted to completely change the way rockets were designed, developed, produced and launched.

The plan was, and still is, for Ariane 6 to be the main workhorse for Europe's space industry, launching European satellites into space on European-built rockets.

The European Space Agency (ESA) took the proposal to its 22 member states. Each had to sign off on the idea.

But the engineers were already hard at work designing the system.

"You need to have your concepts ready. You lay out your production system, how you want to manufacture and assemble your rocket," said ESA's Tina Büchner da Costa, an Ariane 6 launch system architect based at Europe's spaceport in Kourou, French Guiana.

"We had to demonstrate that we could double the launch rate [compared to the rocket's predecessor, Ariane 5], and at the same time reduce the cost," said Büchner da Costa.

In 2015, the first contracts were drawn up: The ArianeGroup, an aerospace company based in France, would produce the rocket, and the French space agency, CNES, got the launchpad. 

And in 2016, they got the green light.

Ariane 6 Timeline: 2017-2019

In 2017, the ArianeGroup began developing its manufacturing chain and producing the first elements of what's called a Flight Model 1 (FM1) version of the rocket.

During 2018 and 2019, four engines were tested and qualified. First, the Vulcain 2.1 engine, which powers the lower stage of the rocket. Then, the Vinci engine in the upper stage of the rocket — the Vinci engine can reignite in space, allowing Ariane 6 to release satellites at different locations on a single mission.

There was also a solid booster P120 engine, and, finally, a new, auxiliary propulsion unit (APU) — all had to be built, tested and verified, step-by-step.

"On every engine, you have several valves and other components that have to be tested at their own level before you can integrate them into an engine," said Büchner da Costa. "Once you go to full engine testing, that's a huge system that you need to test on a dedicated bench."

They built a brand new test bench at a German Space Agency site at Lampoldshausen to test the entire upper stage of Ariane 6.

Meanwhile, in French Guiana, CNES had been digging a massive hole in the ground where eventually they would build the Ariane 6 launch site.

"It all happens in parallel. You take with the smallest products and keep integrating them into a system that becomes more and more complex," Büchner da Costa said.  

Ariane 6 Timeline: 2020-2022

The pandemic years: even Ariane 6 took a hit. COVID-19 had an "immense impact" on construction at the launch site in Kourou, said Büchner da Costa.

"There were 700 people working here and within a few days, they got reduced to 50. The supply in materials slowed, logistics broke down, production in Europe slowed significantly," she said. "You don't feel it at the paper stage, but you do feel it in production."

By 2021, however, they had started moving bits of the rocket from Europe to French Guiana and conducted "early combined tests."

They tested a mock up of the central core of the rocket, the cranes that move it to the launchpad, and the cryogenic arms that fuel and cool the rocket at launch.

And — almost as if it's a side note — they also custom-built the ship they used to transport launcher components so it was more climate-friendly: The "Canopee" sailing cargo ship uses a hybrid propulsion system, partially powered by wind.

Ariane 6 Timeline: 2023-2024

Things started to pick up again in 2023. "We spent the whole of 2023 marrying the launchpad with the rocket," said Büchner da Costa.

The mainstage was tested in French Guiana: "We fired up the main engine and tested the full flight up to [the rocket's initial] separation," Büchner da Costa said. That's after 2'15'' minutes of flight.

The next part of the flight, where the upper stage goes in orbit, was qualified at the new test bench in Germany, "completely separately."

At the same time, engineers in Switzerland tested the fairing — that's the bit that carries the cargo and, perhaps one-day, a capsule for human spaceflight — and the separation of the fairing.

"You test your system, step-by-step, in an incremental way, before you add any critical elements," said Büchner da Costa.

They did five complete countdowns and Büchner da Costa was there for them all: "It was really impressive to see, a full success."

A full success up to 2024: the year of Ariane 6's first full mission with cargo, including cubeSats and scientific experiments.

At time of writing in late June 2024, six launches were planned for 2025 and eight for 2026. By 2027, the ESA aims to achieve a launch rate of 10 per year.

And then keep evolving.

Ariane 6 is about versatility, said Büchner da Costa, calling the rocket an eierlegende Wollmilchsau. That's a German term for which there is no direct translation, but basically means something that can do a bit of everything.

"The eierlegende Wollmilchsau is a pig that gives you milk, wool and lays eggs," da Costa explained. "That's what we want from Ariane 6. The exciting thing is that [Ariane 6] gives us versatility. We want to fly anywhere."

Edited by: Fred Schwaller