It’s a day to forget your lunch break to raise your head to the stars. This Thursday at 2:15 p.m. French time, the Ariane 5 rocket will take off from Kourou, marking the start of a long journey for the European probe Juice. A small event to follow on the Internet, but also live from the Cité de l’Espace in Toulouse from 1:30 p.m., which invited researchers to comment on the launch for the public on this occasion.
A model of European ambition and independence, the mission will keep ESA on its toes for eight years, before four years of studying Jupiter’s moons. But what exactly is this Juice mission? What is the most promising moon for study? And what do we do while we wait for the probe to arrive at Jupiter? 20 minutes enters orbit around Juice for you, with the help of Olivier Sanguy, head of space news at the Cité de l’Espace in Toulouse.
What is Juice?
From his full name Jupiter icy moon explorer. “When we said that, we described the mission,” smiles Olivier Sanguy. The mission and its eponymous probe target “the icy moons of Jupiter, namely Io, Europa, Ganymede and Calisto”. Bodies known for a long time, since they are those that Galileo observed in 1610, which earned them the nickname of “Galilean moons”. If they had allowed the scientist to show that “not everything revolves around the Earth” or the Sun, they had been somewhat neglected since, according to Olivier Sanguy. But “we recently realized that they could have habitable conditions”, the starting point for a renewed interest.
But be careful not to confuse everything: “Juice will not know if there is life” on the moons visited. The objective is to “better understand these moons” and to know if “the conditions are met” for a possible “development of life”. Water, chemical conditions, magnetic field, so many factors scrutinized by the European probe.
Can we expect positive results?
What makes these moons interesting is the presence, under the ice crust, of “liquid water” essential to the development of life. They are even “gigantic oceans”, according to ESA Director General Josef Aschbacher. It remains to be determined whether exchanges take place between the ice and the ocean, which could then integrate nutrients. From this point of view “Ganymede is very interesting”, continues Olivier Sanguy, because it could present “a stack of layers of ice and oceans”.
The largest moon of Jupiter, a size close to that of the planet Mercury, will also be the central object of the Juice mission in a second stage; from 2035, the probe will enter orbit exclusively around Ganymede, a first. “It has its own magnetic field, and can therefore be protected from the aggressive radiation of Jupiter.” Here again, the presence of a magnetic field is essential for the development of life, making it possible, for example, to preserve an atmosphere and above all, in the case of icy moons, not to be continuously irradiated. In addition, the presence of liquid water, at such a great distance from the Sun, is explained by “significant gravitational tides, which heat up” the satellite. Liquid water, magnetic shield and heat, all elements that could favor the development of a form of extraterrestrial life. Even if we’re talking about microorganisms, not little gray men.
What do we do for 8 years?
The ESA has other probes in the cosmos than Juice, and between analyzing the current data and planning future missions, there is no need to sit idly by. Plus, the trip isn’t going to be easy for Juice. “Jupiter is far”, but “if we arrive too quickly, it will be difficult to get into orbit”, explains Olivier Sanguy. So, to arrive in the best possible conditions, the probe will save fuel and use the “gravitational assistance” of the Earth several times, but also of Venus. This already represents time dedicated “to navigation” in addition to offering “a little science of opportunity”.
But above all, “the teams will prepare and rehearse the navigation” that awaits them once Juice arrives around Jupiter. With “35 flybys of the moons of Jupiter from 2031 to 2034”, each of which requires “the right trajectory and the right orientation” to optimize data collection, hours of simulations await the teams of engineers. “It’s going to be very intense,” warns Olivier Sanguy, especially since an unprecedented step awaits Juice: entering orbit around a satellite, Ganymede, from 2035. “Luckily we have eight years to prepare “, breathes the Toulousain.