Flagship mission of the European Space Agency (ESA), Juice (the acronym for Jupiter Icy Moons explorer, “the explorer of the icy moons of Jupiter”) is due to take off at 2:15 p.m. (Paris time) from Kourou in French Guiana , aboard an Ariane 5 rocket, which will be the penultimate flight, before being replaced by Ariane 6. This is the first mission to target the giant planet since the American mission Juno, launched in 2011.
“The weather conditions are good”assured Wednesday Marie-Anne Clair, the director of the Guiana Space Center, in the Jupiter control room, where personalities were gathered, including the King of the Belgians, Philippe, or the French astronaut Thomas Pesquet.
The probe will separate from its launcher 28 minutes following takeoff, at an altitude of 1,500 kilometers, said Arianespace President Stéphane Israel. Juice will then begin its long cruise to Jupiter, the largest planet in the solar system, approximately 628 million kilometers from Earth.
“One of the most complex machines ever sent”
Designed by Airbus, Juice carries ten scientific instruments (camera, spectrometer, radar, altimeter, magnetometer, etc.), protected from extreme temperatures by a multi-layer insulation cover. The probe is also equipped with huge solar panels of 85 m2 – the equivalent of a basketball court – to supply it with energy, in an environment where sunlight is 25 times weaker than on Earth. “It is one of the most complex spacecraft ever sent to the outer solar system”explained ESA Director General Josef Aschbacher.
Its arrival in the vicinity of the giant planet is scheduled for July 2031. Before that, the probe will have to go through complex maneuvers of gravitational assistance, consisting in using the attraction force of other planets, to use them as catapult. A flyby of Venus in 2025, then once more of Earth in 2029, will allow it to gain momentum towards its destination, the moons of Jupiter, discovered by the Italian Galileo at the beginning of the XVIIe century: Io the volcanic and its three frozen companions, Europa, Ganymede and Callisto.
In search of liquid water
The Jovian system has “all the ingredients of a mini-solar system”, developed Carole Mundell, Director of Science for ESA. His exploration “will make it possible to study how our solar system works, how the planets are formed”.
Juice’s main quest is to find not life directly, but environments for it to appear. If Jupiter, a gaseous planet, is uninhabitable, its moons Europa and Ganymede would be ideal candidates: under their icy surface, they shelter oceans of liquid water, considered to be the main ingredient allowing the appearance of life.
For more than three years, which will represent the first phase of her mission, Juice will carry out thirty-five flybys of the three satellites – two for Europa, twelve for Ganymede and twenty-one for Callisto – which she will inspect using her ten implements.
In 2034, it should be placed in orbit around this Ganymede, the largest natural satellite in the solar system (2,634 kilometers in radius) of a size comparable to the planet Mercury. It is also the only moon to have its own magnetic field protecting it from dangerous solar radiation, like the Earth.
“The Mission of a Decade”
Previous space missions have suggested the presence, between two thick crusts of ice, of a gigantic ocean, “several tens of kilometers, much deeper than the Earth’s oceans”underlined Josef Aschbacher.
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One of the questions is whether this liquid water interacts with the surface to be able to absorb its components. Such a reaction would allow the appearance of nutrients, one of the conditions for the development of an ecosystem conducive to life.
At a total cost of 1.6 billion euros, Juice is the first European mission to explore a planet in the outer solar system, beyond Mars and the Kuiper belt. “It’s the mission of a decade”underlined Josef Aschbacher.
NASA, for its part, is preparing the departure of the Europa Clipper probe, whose departure is scheduled for the end of 2024, targeting the Europe satellite. The American agency hopes to determine if, under the inhospitable surface of this icy moon, exist environments suitable for life.