The European probe Juice is living its last moments in Toulouse. At the beginning of February, the spacecraft will leave the clean room of Airbus builder son to reach the launch pad in Kourou and prepare for a hoped-for takeoff on April 14 aboard an Ariane 5 launcher. A long eight-year odyssey will then begin before reaching Jupiter’s orbit and setting off to discover of its moons.

3.5 tons of fuel on board

” Ariane 5 is our most powerful launcher, but it cannot send the probe directly to Jupiter. During the first years of the mission, we will have to perform several gravitational maneuvers by flying over Venus and several times the Earth to pick up speed and finally reach Jupiter in the summer of 2031 and begin observations. explains Giuseppe Sarri, Juice project manager at the European Space Agency.

” These gravitational assistances also make it possible to minimize the quantity of fuel necessary for the mission. “, completed Cyril Cavel, Juice project manager at Airbus Defense and Space. Even if it will still take 3.5 tons of fuel on board, more than half the mass of the spacecraft of 6.2 tons. Fuel management will also be crucial for the duration of the mission, which must last at least four years..

Safes against the power of radiation

Beyond the fuel autonomy and the extreme temperatures encountered during the journey (from 250°C during the flyby of Venus to -230°C around Jupiter), the main technical challenge of the mission was for Airbus to protect the spacecraft from the gigantic radiation expected during the journey.

” One of the particularities of this mission is that the probe will have to survive a very aggressive radiative environment. Around Jupiter, the probe will be permanently bombarded by very high energy and very high speed particles which will strike the external surfaces of the satellite, impact the internal equipment and quickly damage them. “, describes Cyril Cavel.

To limit this phenomenon, Airbus has developed for the first time a system of safes (the first is placed under the antenna, and the second at the rear of the probe) shielded with lead to protect the most sensitive equipment and especially the electronics these radiations. ” The 150 kg of lead on the satellite makes it possible to slow down this process so that the probe can achieve all of its scientific objectives before the damage is too great. adds the project manager.

The mission engineers also carefully calculated all the stages of the circuit to mitigate the impact of this particle bombardment. ” We have an overall radiation budget for the whole mission and we try to minimize the time spent at a certain distance from Jupiter depending on the radiation dose received “, deciphers Nicolas Altobelli, responsible for the Juice mission within the European Space Agency. Reason why the spacecraft will fly over the moon Europa only twice, whose magnetic field is very important.

400 years after the first observations of Jupiter by Galileo, the Juice probe will collect data using ten scientific instruments to shed light on understanding Jupiter and its three main moons (Ganymede, Europa and Callisto). Under thick layers of ice, the latter could shelter immense oceans having been able to see forms of life develop. ” Jupiter is a gas giant planet, as there are so many in the universe. This physical phenomenon, which keeps liquid water below the surface, is perhaps one of the most dangerous habitats in the universe. », concludes Nicolas Altobelli.