3… 2… 1… liftoff!

What comes to mind when the team casts their minds back one year?

Claire: “I was extremely lucky that I got the chance to be in Kourou. It was my first ever launch. And what a launch! Just to see and to hear and to be so close to the launchpad. There was a lot of light and then a lot of noise. It was an incredibly intense experience.”

Claire, who works on planning the operations of Juice’s ten science instruments, has worked on Juice since 2015.

“When you work for so long on a mission that is still a bit abstract, you’re never 100% sure that it will actually be launched – even if, of course, you are confident that it will be!

“But just seeing that rocket in the sky, and knowing that’s your spacecraft inside, that’s when the big adventure actually begins.”

For Giuseppe, who led the Juice project between 2014 and 2023, the talk of launch brings back more anxious memories.

Giuseppe: “When you have a launch window, you have to launch during this window. You cannot simply add one month. Our window started on 5 April and was closing towards the end of April.

“The final testing and preparations were going well until a propulsion system test threw up a nasty problem. We were testing a failure case which means we simulate a failure in a few of the thrusters, and then the system has to reconfigure. But it was reconfiguring with less thrust than we would have liked.

“We could not afford to launch with the risk that in case we have a failure, we would lose the spacecraft. So the Airbus team had to work around the clock to make a change to the software to make the system safe again.”

Airbus led on building the Juice spacecraft. It’s clear that our ESA team are in awe of what they have achieved.

Giuseppe: “On the day of the launch, everything was good with the spacecraft, good with the launcher. But the weather was not cooperating. We came very, very close to launch, but then we had to stop. And that was a little bit demotivating.”

Fortunately, the next day, the lightning strikes stayed away and Juice was cleared for launch. Back in Europe, Olivier took a moment to breathe after a stressful few weeks.

Olivier: “I think that was the most intense period of my career: these few weeks around the launch and then the launch itself. Then 10 seconds before launch, as the countdown began, I said to myself, ‘right, so now there’s nothing more we can do, it’s going…’.”

Meanwhile, in the mission control room, Ignacio led a focused team of front-row mission controllers.

“Until acquisition of signal everything is always so tense, because whatever happens is completely out of your control. You can’t see the spacecraft, you can’t speak to the spacecraft, and whatever happens, you can’t act on it.

“So you’re just sitting there waiting and waiting, with your hands tied. Then when you finally get telemetry you breathe a sigh of relief because you know the spacecraft is alive. And then when you send up a command and establish contact with the spacecraft you again breathe a sigh of relief because your training kicks in and whatever happens, you are confident that the team can deal with it.

“From that moment, you’re extremely busy. It’s one task after another. You just keep moving. For Juice, after 23 hours, we were done. I think it was the fastest launch and early operations phase we have ever completed. Then we moved upstairs to the dedicated planetary control room to start with commissioning the spacecraft and instruments. And that’s where the real problems began.”

The antenna carrying Juice’s Radar for Icy Moon Exploration (RIME) instrument was stuck. After being folded up for launch, it refused to open up in space. The science that Juice would be able to achieve at Jupiter was compromised.

Giuseppe: “The expectation for a mission like Juice, which is a cornerstone of science, is absolutely huge. There are high expectations from ESA Member States, from the people putting the money on the table. If the mission doesn’t work, it’s a failure of the European Space Agency.

“But most of all there are hundreds of people who have made their scientific career based on this mission. They could all have their career ruined. And I really felt that pressure at that moment.”

The team are unanimous in their conviction that the RIME antenna was what wracked their nerves the most over the past year. Ignacio tells us more about the issue.

Ignacio: “The antenna is made from flexible material. When we hit release, we expected it to flip itself open like one of those folding camping tents. We were concerned that if it was kept stored for too long, it would lose its properties, so we wanted to deploy it as quickly as possible.

But upon release, the antenna didn’t fully deploy. This scenario was not one that Ignacio and his team had trained for.

Ignacio: “No one had thought of this, so we had to proceed very carefully. Pretty much every week we had to throw our latest plan out the window and start from scratch. This antenna was a thorn in our side, continuously present day and night, blocking everything.

“It took about a month of continuous work, and the pressure was completely different from during the launch and early operations phase. But fortunately, we were supported by very competent and professional individuals from industry, from the Juice project team, and within our operations team, and ultimately we were successful.