12/04/2024
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One year since the launch of ESA’s Jupiter Icy Moons Explorer (Juice), we catch up with core team members Claire Vallat, Giuseppe Sarri, Olivier Witasse and Ignacio Tanco.
From memories of launch day to hopes for the future, they talk honestly about the ups and downs of flying a space mission, and reveal how they’re ensuring that Juice will be a huge success.
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 RIME antenna – a thorn in our side
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.
“We uncorked a celebratory bottle right then because everybody had just had enough of this stuck antenna! It wasn’t my victory, it wasn’t an ESA flight control team victory, it wasn’t even an ESA victory. It was a European victory.”
Claire had been closely following the progress of freeing the RIME antenna.
Claire: “This was an extremely tense period for the project and industry teams. A lot of ups and downs. It’s something I will keep in my head for some time.
“Because of this issue, we lost about a month of commissioning time, and we had to make up for this lost time. Fortunately, the rest of the instrument commissioning went smoothly and the review at the end was very positive. Some instruments are working even better than we expected.”
A perfect launch = extra science at Jupiter
Juice will spend just four years exploring Jupiter and its icy moons, so there will not be much time after arrival to review scientific observations and repeat measurements. To ensure that the mission is ready to do great science as soon as it arrives, Olivier and Claire are already working on a plan. Together with the teams leading each science instrument, they have had to take a few big decisions over the past year.
Olivier: “Our first decision was easy. The launch was perfect, and we launched at the right moment within the launch window. This meant that certain manoeuvres were not needed so we were left with more propellant than expected. This extra propellant will be used to reintroduce a phase of the mission that was scrapped a few years ago because of limited mass budget.
Claire: “We will go down to just 200 km above Ganymede’s surface. This will provide much better data in several aspects, especially for everything related to the geophysical investigation of Ganymede. Being so close, we will have better data to characterise the interior of the moon and its plasma environment.
“This is great, great news for the science team because they had to descope this part of the mission a few years ago. But it had always been in their minds that it should be recovered, if at all possible.”
Juice’s first health check
Juice’s instruments must be kept in prime condition for arrival at Jupiter. In January, they underwent their first health check.
Claire: “Roughly twice a year the mission operators switch on the instruments and we do some tests. These can be simple, for example, functional checks of the health of each instrument. They can also be a bit more complex, like interference tests between different instruments.
“This one was, of course, our first time. And you never know if things can go wrong or if you made any mistakes while developing the plan.”
Thankfully all ten instruments passed their health checks with flying colours. But four had to undergo planned surgery.
Ignacio: “We knew already at launch that the onboard software on several of the instruments was just a placeholder, that needed updating to operate successfully at Jupiter. Updating software is a delicate operation because you need to basically patch the entire memory. Then you need to reboot. But in the end everything ran without a hitch.”
The dreaded spacecraft brain upgrade
The spacecraft itself also required a software update. The process is a bit like updating your phone or computer’s operating system, but much more complicated and much, much more stressful.
Giuseppe: “Though the spacecraft was safe at launch, the onboard software did not have all the functions necessary to operate the spacecraft at Jupiter. So we agreed with Airbus that we would patch this in flight in 2024 to give them more time to finish the development.
“There was a moment where we had to load the software and put in memory. Then there was another moment where we had to switch off the old software and switch on the new one. In this transition, the spacecraft had to go into a safe mode, where it had to do by everything by itself.”
Ignacio (with emphasis): “We hate doing this because switching off the spacecraft means that for some minutes you actually don’t see it.
“We had 20 minutes where we were convinced that we should be hearing from Juice but we weren’t.
“It should have come back.
“It should be there.
“Come on.
“What’s going on?
“At that moment you start having all these different scenarios going through your head. You know you cannot act, or rather you should not act. Because if you start acting blindly, the chance that you make a problem worse is high, so it takes discipline to wait, to not take action.
It sounds enormously stressful. How does Ignacio stay calm in these situations?
Ignacio: “I meditate.” [he says simply, shrugging]
“I sit down and breathe for 35 minutes a day, and this helps me a lot. I very often think it is probably the one tool that makes the biggest difference in how I approach work and how I deal with the unexpected stressful situations.
“But I must say it’s a big part of the intellectual satisfaction of spacecraft operations, actually dealing with these things and overcoming them.
“Anyway, after a short delay, we got telemetry from the spacecraft. We have the new software active on board and it’s working very well. We managed to resolve a lot of the existing problems – small bugs that we had identified that were all corrected by Airbus. We now have a much cleaner spacecraft to run.”
The double flyby – a balancing act in more ways than one
Claire: “We’ve recently entered what I would say is our first conflict negotiation and resolution with the different instrument teams. The flyby of the Moon and Earth in August is the only opportunity we’ll have for certain measurements during the cruise phase. Understandably, everybody’s interested in getting science out of it.”
Later this year Juice will fly by first the Moon then Earth in quick succession, on a world-first attempt to use the gravity of both as springboard towards Jupiter. This lunar-Earth gravity assist is also something of a bonus for instrument calibration and science, possible only because Juice launched during a very specific time window.
Olivier and Claire recently had the challenging task of figuring out which instruments to operate at what moments during the unique lunar flyby. The process has led to debate between instrument teams.
Olivier: “Our highest priority during the cruise phase is to ensure that we are ready to do maximum science at Jupiter. Unfortunately, we have another issue with the RIME instrument: it is picking up some disturbances within the spacecraft. The Moon flyby is the only chance we have before we arrive at Jupiter to test how this background interference is degrading the performance of RIME. The team can check this aspect by analysing echoes from a surface, and developing an algorithm to correct the problem.”
So far, so straightforward, but making time for RIME means less observing time for the other instruments. Following weeks of lively discussion, the final decision was made: RIME will have some time to observe alone during the closest approach to the Moon, during which time all other instruments will be switched off or in quiet mode.
Olivier: “Having to face these negotiations now is really valuable because it helps develop the discussion processes and the trust in each other. It’s so important to build trust so that people know that we act fairly, that we listen and that we try to strike a compromise.”
Claire: “The big difference is that here we are in spring and we’re planning for a flyby occurring in August. During the Jupiter tour we will have event after event after event – sometimes several Galilean moon flybys and close approaches to Jupiter per month. We need to pre-empt some of the conflicting needs of the instrument teams to ensure that we can cope with the intense operations during the nominal mission.”
Working together for a successful mission
Claire: “Juice is enormously complex not only from an engineering or scientific point of view, but also from a human point of view. We have so many teams spread around the world, with different ways of working and sometimes slightly different interests. A big part of our jobs is to ensure that all these people are aware of the different scientific, technological and operational constraints so that we are all working for the best of the mission.
“This is extremely complex but extremely rewarding. You have the feeling you’re achieving something big, you know? You’re just a small piece of it, but the full puzzle is just amazing.”
Giuseppe: “From the very beginning we aimed to have honest and transparent communication between the different teams. I never pointed the finger. My team never point the finger. And as a reward, the instrument teams, whenever there has been a problem, have never pointed the finger at ESA.
“I’m very proud of how we all worked together and what we’ve managed to achieve.”
Olivier: “In November we released the full two-hour making of Juice documentary, which I think gives a really good behind-the-scenes insight into how a project team works together with industry and scientists, into how we build a spacecraft.”
Ignacio: “I see myself, as they say, standing on the shoulders of giants. The entire team here at mission control has been working continuously at a very high level over the last year.”
Juice is still Juice, and the pressure is still high
So now that Juice is in space, do the team see it in a different light?
Olivier: “Oh no. No, no, no, no, no.
“Juice is Juice! It’s a great mission, a completely fascinating mission. It’s just that the phase has changed, so now we have a real spacecraft in space to operate. For me it’s a transition and I try to navigate the best for this. I know there are a lot of challenges, so that’s why I’m still focused, concentrated on my task, and making sure that we don’t waste any time.
“Because every single thing that we do now is to make sure we are ready in seven years when we arrive at Jupiter. We can’t afford to hibernate our minds.”
Giuseppe: “With space exploration, you really have the feeling that you are walking on the edge of a mountain. A step to the left is a full glory. A step to the right is full disaster. The difference between full glory and full disaster is not that big. You don’t always know how it will go. And that is really what makes things interesting, exciting and satisfying.”
If you enjoyed this article, meet more scientists and engineers who have worked on Juice in our feature-length documentary, The making of Juice.