Europe is aiming to regain independent access to space with the first launch of its new heavy-lift rocket, Ariane 6, from French Guiana on Tuesday.
The European Space Agency has had to rely on Elon Musk’s SpaceX to send its most sensitive satellites into orbit since it retired Ariane 5, once one of the world’s most reliable rockets, in July last year. Ariane 6 will be more flexible, with a restartable upper stage able to deposit satellites in different orbits on a single mission.
Four years late and with a price tag of about €4bn, the 56 metre-tall Ariane 6 will attempt its first flight between 3pm and 7pm local time.
But more than 10 hours earlier, before dawn breaks over the vast forested area in South America that is home to the Guiana Space Centre (CSG), engineers will begin the official countdown, an orchestration of checks and milestones required for a successful flight. Even then, close to 50 per cent of first flights fail.
In the Jupiter control room, Raymond Boyce, launch range operations director, will monitor a giant screen displaying the status of systems covering the weather, telemetry and other factors. The status will change from red to green as engineers in the launch centre — a concrete bunker 4km from the launch pad — complete each task.
Four officials from the French space agency CNES, who are charged with aborting the mission if there is any risk to the local population, will gather in another room. “They are isolated from bosses who want to say ‘No, no, I don’t want you to destroy the launcher’,” said Thierry Vallée, who is in charge of safety at the spaceport.
Once everyone is in place, the teams will test the countdown systems and data transfer from the seven ground stations stretching from Bermuda to Australia. Radar systems are calibrated and weather balloons sent up to assess conditions at high altitude.
With about five and a half hours to go, staff at the weather station 5km from the launch pad will provide a detailed briefing to the directors who give the final approval for launch.
The biggest weather risk is lightning. Any such risk within 10km to 20km of the launch site could stop the mission. For example, if the rocket has to pass through clouds at very high altitudes, there is a chance that a build-up of electrical charges could trigger lightning.
“The rocket can’t explode, but the payloads inside and avionics equipment can be affected,” said Anne-Sophie Chassagnou, chief forecaster for the Ariane 6 flight. “We really want to avoid that.”
When the fuel tanks have been filled with liquid oxygen and hydrogen, roughly four hours before launch, communications between the launcher and launch base are tested.
Two important milestones follow. “Twenty minutes before launch is the last time we can stop due to winds at high altitude,” said Boyce.
Ten minutes later, the weather team will give its final detailed briefing before heading into another underground bunker where they will continue to update forecasts.
“We have all our systems [in the bunker],” said Chassagnou. “But, obviously, for a weather forecaster, it’s better to have windows because the first instrument is our eyes.”
Chassagnou, who has worked at CSG for just over three years, has only seen one launch live.
Five minutes before launch, the countdown moves into its automated phase — if any system flashes red on the control room screen, the launch will be halted automatically. The teams can still manually abort the mission up to seven seconds before lift-off when the rocket’s Vulcan engines ignite.
As the engines fire up, a torrent of water is released on to the launch pad two seconds before flight to dampen noise and mitigate heat damage from the engines. “It is almost 1mn litres in about 30 seconds,” said Vallée.
Finally, the “cryogenic” arms holding the rocket must be released with less than one second to go. “If they do not open, the launcher will destroy everything [in the vicinity],” said Boyce, with a nervous smile.
Once opened, the 540-tonne rocket will lift off on its two-hour and 40-minute mission to deliver 17 satellites and experiments into space, with the ESA, Nasa, universities and start-ups each paying between €1,000 and €5,000 for the service. After the payloads are delivered, the engine will reignite to dispose of the upper stage and avoid leaving debris in space.
Much can still go wrong after lift-off. But lessons will be learned even if there are problems.
With Ariane 6’s restartable upper stage on its first outing, issues are to be expected. “If it fails . . . when we test the behaviour of the upper stage, I will say it’s not a failure,” said Michel Bonnet, the ESA’s head of Ariane 6 mission engineering. “I’m quite confident that for the very first part of the flight, the risk of having a failure is much lower.”