Under the Sun Toulouse on this beautiful and cool day of April 5, 2022, our guides from the European Space Agency (ESA) and Airbus Space welcome us and prepare us to enter the clean room. Disinfection of equipment, we pass blouse, overshoes and charlotte. It’s not every day that you get to see an almost complete European interplanetary probe. We walk between the satellites being integrated in the Airbus Space clean room, the project manager of the ESA probe. Passing between the test rooms, we see a telecommunications satellite waiting to be plunged into a gigantic vacuum chamber for thermal tests.
Finally we arrive in front of the room Mistralthe anechoic chamber dedicated to acoustic and communication tests. It is a large room 15 meters high whose all sides are covered with small pyramids of moss who swallow all resonance. The room is perfectly soundproofed. Juice awaits us there.
The probe is almost complete. It’s just missing the solar panels, they will be attached a little later, after several tests. Juice must be ready to leave for Kourou in January 2023, for a shooting campaign Guiana Space Center which will last three months. Finally, the probe will take off aboard the very last rocket Ariadne 5from April 5, 2023.
A long series of tests in Toulouse
When we arrived, Juice was coming out of a series of communication tests in the Mistral room. Airbus Space and ESA simulated communications between the probe and the Operations Center in Darmstadt, Germany, ESOC, from where it will be piloted. Thibault Ravily, engineer at Airbus Space for almost ten years, joined the Juice adventure in April 2019 as Test Manager. He certifies that these last tests have been successfully completed.
Juice will still stay some time in the Mistral room for new tests ofinterference. For three weeks, Thibault Ravily and the Airbus engineers will now carry out tests of compatibility electronics of the probe, as well as its compatibility with Ariadne 5. ” Antennas are placed at specific locations – in the room – given by Arianespace, then electromagnetic levels are measured “, explains Thibault Ravily, to ensure that the probe and the launcher do not disturb each other.
Self-compatibility tests, that is to say consistency between the probe and its scientific instruments, are still to come. Also on the program, new thermal tests in a vacuum chamber. The probe has passed some before, but not when it was complete. The tests can be long, and regularly require us to work on them 24 hours a day, with relays from the teams. The Juice project alone should bring together a consortium of a thousand people.
The probe is completely integrated with the exception of the solar panels
The structure of the satellite platform was received in 2019. Little by little, Airbus Space added all the subsystems necessary for its proper functioning: navigation, propulsion, wiring, etc. Many subsystems and equipment come from suppliers external to Airbus Space, some of which are based in Toulouse. As Juice is a European mission, ESA has ensured that the geographical return is respected.
It was no easy task for Airbus Space to synchronize the integration of each of these components. Each had been tested before, including one in an observatory. This is the case of the NavCam, Juice’s navigation camera, which helps him find his bearings in relation to the position of moons of Jupiter or stars that the probe will fly over on the way. NavCam had been tested with the Moon from the Pic du Midi observatory.
Almost everything is duplicated, especially thecomputer board, in which ” each of the components has been mounted in duplicate “says Thibault Ravily. On the propulsion side, only the nozzle of the main engine is unique. All the other booster engine nozzles were double-mounted for greater safety. For general orientation, the probe is equipped with a trackerstar additional. A first is needed to determine an axis and another to determine a plane so that the probe knows the orientation of its three axes of rotation (like the pitch-roll-yaw trio in aviation). So Juice has a spare third. The redundancy of equipment is essential for this type of mission.
Once the satellite platform of the probe is complete, ESA has sent to the European Center for Space Research and Technology, the Estec, to make it pass long thermal tests in a vacuum chamber. Then, the probe was transferred in 2021 to Toulouse for the integration of the ten scientific instruments. More precisely, it is the instrument flight models that have replaced the test models. After this phase of testing the entire probe, all that remains is to integrate the solar panels and test their deployment before sending everything to Kourou. ” The timing is right ! “, assures us Thibault Ravily.
New flight plan
This is a great novelty for the mission. Initially, Juice was to leave earlier, but the delays in particular related to the health crisis forced the ESA to postpone the flight to 2023. The teams realized that there is a magnificent option for ” save time andenergy by launching it in the spring, tells us Manuela Baroni, AIT manager and Juice launcher interface at ESA.
On the program, many flyovers of planets of Solar system before entering the system Jovian. These overflights make it possible to use the gravity planets as an accelerator to have the speed sufficient to reach Jupiter while spending a minimum of fuel.
The window Firing lasts a few weeks and begins on April 5, 2023. For more than a year, Juice will revolve around the Sun before flying over Earth for the first time in August 2024. But just before, the probe will also use the Moon as a gravitational assistant, which is really not common.
This will be followed by an overview of Venus in August 2025. On this occasion, Juice teams will test their scientific instruments. After that, the probe will fly over Earth twice more, in September 2026 and August 2029. It will then have enough speed to reach Jupiter in July 2031.
The mission will begin with a first overview of Ganymedethen the probe will take time to reduce its orbit around Jupiter. In July 2032, Juice will fly over Jupiter’s first icy moon for the first time, Europe. The moon will not be studied too much by Juice because the Nasa planned to send the Europa Clipper probe from 2024. As for the last icy moon Callisto, it was planned to make 21 flybys there.
Finally, in December 2034, Juice will orbit Ganymede and will revolve around it until the end of 2035, when it will be decided to crash the probe on its surface. The mission will be officially completed in 2038, with thearchiving Datas.
Voyage of the Juice probe and visit of the Jovian system. © ESA, YouTube
A mission with new objectives
In reality, it is not the ESA which is at the origin of the project but the agency has always dreamed of a mission to Jupiter. The project dates back to the Laplace program, a joint mission between NASA and ESA. Finally, the mission was split into two: Europa Clipper on the NASA side and Juice on the European side through the ESA’s Cosmic Vision program. The Juice project was adopted by the agency in 2012. Today, this fantastic mission will cost a total of almost 1.7 billion euros.
The Juice probe (Jupiter ICy moons Explorer) will help achieve two goals: to provide data on the environments of Jupiter’s icy moons potentially capable of supporting extraterrestrial life. The data on Ganymede will be very useful for this. The second objective is to observe the Jovian solar system ” like a miniaturized solar system “says Manuela Baroni, in order to find out more about the formation of our planetary system.
The Juice project also has another objective that is not really scientific: to test the development of new technologies for studying Jupiter’s moons up close despite their great distance from Earth. This development could be used for much more ambitious later missions, such as interplanetary manned flight. As Manuela Baroni likes to say: “ Man has always been an explorer! »
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