When, in 1979, the American probes Voyager-1 and 2 flew over Jupiter and its procession of moons, the images they sent back of one of them, Europa, were surprising: this satellite, a little smaller than our Moon, did not doesn’t look like it at all. No large volcanic outpourings, no craters, but an intriguing bluish, smooth surface, crossed by fracture lines of a color tending towards red-brown.
Europa is a ball of ice whose crust cracks under the tidal effect imposed on it by the mass of the giant planet. Scientists quickly become convinced that the ice covers a global ocean. But, also, that it rises to the surface via the rectilinear crevices and that the reddish deposits are witnesses to it. The oceanic promise is then coupled with a tantalizing scenario: what if life was possible there? It is to explore this hypothesis that NASA is launching an ambitious mission called “Europa Clipper”, which left Earth on Monday October 14 aboard a SpaceX Falcon Heavy rocket.
Europa Clipper leaves a year and a half after Juice, a European Space Agency (ESA) mission whose main target is another satellite of Jupiter, Ganymede, also equipped with a buried ocean. This craze for these icy moons and this hope for extraterrestrial life may be surprising if we consider that the Jovian environment is not the most welcoming, full of radiation and, above all, far from the Sun: we receive there- bottom of our star twenty-five times less energy than on Earth.
Nothing serious actually. The discovery of black smokers at the bottom of the earth’s oceans, where total darkness reigns, caused “a paradigm shift on the question of habitability: we had life and an entire ecosystem without the slightest light, explains Arnaud Boutonnet, mission analyst manager for Juice at ESA. Life requires liquid water, contact with rocky soil for nutrients, and a source of energy. » In the absence of the Sun, the tidal effects experienced by Jupiter’s moons provide them with this energy.
Also read the decryption (2023) | Article reserved for our subscribers Mission Juice: departure for the icy moons of Jupiter
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As Gina DiBraccio, director of NASA’s planetary science division, assures, “Scientists believe that Europe is one of the most promising places for the search for life beyond Earth. But let’s be clear: Clipper will not seek life itself but will characterize the habitability of Europe. »
The probe will not land, drill the ice, or dive into the ocean. Once in orbit around Jupiter, in 2030, it will simply fly over the satellite regularly and analyze it from every angle using its nine instruments, including a radar whose mission will be to describe the structure of the crust and look for the presence of possible lakes within it. Another primary task assigned to the probe: understanding the composition of Europa and the red-brown materials seen there, determining the depth of the ocean, its salinity and its interactions with the surface.
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