‘Juno’ probe visits Europa, Jupiter’s icy satellite | Sciences

Europa, the second satellite of Jupiter discovered by Galileo in 1610, is about to receive a new visit from Earth: 22 years after the probe’s visit Galileo Today, the satellite arrives boat Junewhich has been orbiting the giant planet since July 2016.

The a task June Planned to complete 37 orbits around it Jupiter for less than two years. They are very long tracks, reaching distances of more than 5 million km at the furthest point to descend less than 5,000 km at perigee (accurately, “Peregovian”, to use the new term invented for the occasion).

While flying at high levels, June It moves at a certain slowness, but its passage through this gutter does it like an exhale, at a speed of 60 kilometers per second. This is the way that Fly over the poles of the planetto reduce the damage caused by crossing the besieged radiation belts.

There are precedents, like the previous one, the probe Galileo. In 2003, it damaged one of its data recorders, leaving it inactive for weeks until technicians were able to fix it in a “electronic surgery” operation some seven hundred million kilometers away. Of course, that ship was moving in a low equatorial orbit and more susceptible to high doses of radiation; The June Not only do they fly on a less dangerous path, their more sensitive instruments are enclosed in a kind of safety by centimeter-thick titanium walls. without that protection, The electronics on board were “fried” in the first orbit.

The desired goal is June It was only a study of Jupiter. Its trajectory has not been calculated to approach any of its satellites. In fact, it only occasionally passes close to one of them. The most exciting occasion was in June of last year, when more than a thousand kilometers passed over it Ganymede, the largest satellite of Jupiter. Since it was a very quick encounter, he was only able to get some pictures, yeah, Excellent quality.

The appointment with Europe on September 29 will last only a few minutes. The distance will be about 350 kilometers, which will allow to record much more detailed images than those currently in place. The geometry of the encounter will allow to observe areas that could not be clearly seen in the previous images. The onboard camera, initially designed to study Jupiter, will take several images as it flies over the illuminated hemisphere. As for the dark June You’ll get one photo—just one—with its star sensor, which is adapted to faint brilliance of stars. At midnight, the illumination will come from the sun’s reflection in Jupiter’s clouds.

Europe is a frozen world almost without rest. Someone compared it to a cosmic billiard ball. It is believed with some certainty that the ice sheet, probably tens of kilometers thick, hides an ocean surrounding the entire star. On its snow-white surface there are many dark grooves, perhaps rocky material exuding from deep layers. On the other hand, in some areas you see what look like huge, braided icebergs that are irregularly connected to each other. Many retain the original grooves, but they do not fit together. It is as if the frozen layer in the distant past had partially thawed and then refrozen, trapping the floating blocks of ice in a poorly assembled puzzle.

There are indications that Europe, such as Enceladus, the small satellite of Saturn, jets of water are emitted through a crack in the ice. Just as they were depicted in detail on Enceladus, there is no conclusive evidence in Europe yet. This will be one of the objectives that the probe will have to study europe scissorsslated for launch in 2024.

This meeting takes place during the 45th orbit of June around Jupiter, more than double what was initially expected. In February 2024, a final confrontation will take place with another Galilean moon: Io, the world of four hundred volcanoes. It will be in orbit 58, a record for surviving in a hostile environment like the one this ship endures.

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