When the American probes Voyager 1 and 2 flew past Jupiter and its moons in 1979, the images they sent back of one of them, Europa, were surprising: This satellite, slightly smaller than our own, was not. It doesn't look like that at all. There are no major volcanic flows, no craters, but an interesting smooth bluish surface, intersected by reddish-brown fault lines.
Europa is a ball of ice whose crust cracks under the influence of the tides imposed on it by the mass of the giant planet. Scientists soon became convinced that ice covered a global ocean. But it also rises to the surface through straight cracks, and the reddish sediments are evidence of it. Then the oceanic promise is coupled with a puzzling scenario: What if life were possible there? In order to explore this hypothesis, NASA is launching an ambitious mission called Europa Clipper, which departed Earth on Monday, October 14, aboard a SpaceX Falcon Heavy rocket.
Europa Clipper departs after a year and a half of Juice, a European Space Agency (ESA) mission whose main target is another satellite of Jupiter, Ganymede, also equipped with a buried ocean. This obsession with these icy moons and this hope for the existence of extraterrestrial life may be surprising if we consider that Jupiter's environment is not the most hospitable, full of radiation and, above all, far from the Sun: there, below our twentieth star, we receive – five times less energy than on the earth.
Nothing serious actually. The discovery of black smokers at the bottom of the Earth's oceans, where complete darkness reigns “A paradigm shift in habitability: we had life and an entire ecosystem without the slightest light, explains Arnaud Boutonnet, Juice mission analyst director at ESA. Life requires liquid water, contact with rocky soil for nutrients, and an energy source. » In the absence of the Sun, the tidal effects of Jupiter's moons provide them with this energy.
Possible lakes
As Gina DiBraccio, director of NASA's Planetary Science Division, confirms, Scientists believe that Europe is one of the most promising places to search for life outside Earth. But let's be clear: Kleber will not be looking for life per se, he will be determining the liveability of Europe. »
The probe will not land, drill through ice, or dive into the ocean. Once it reaches 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 task will be to describe the structure of the crust and search for the presence of possible lakes. Inside it. Another key task assigned to the probe: understanding the composition of Europa and the red-brown materials seen there, and determining the depth of the ocean, its salinity and its interactions with the surface.
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