NASA’s Juno spacecraft has been orbiting Jupiter for four years, observing its moons along the way. But only now he first photographed from a distance of 100,000 km the North Pole of one of them – Ganymede, where plasma “rains” are constantly falling.
Ganymede is extremely interesting. It is the largest satellite in the solar system with a diameter of 5267 kilometers (which is 8% more than the diameter of Mercury). It consists of water ice and frozen silicate rocks. Some scientists believe there may be an ocean of water beneath the surface of Ganymede.
Among its many fellow solar systems, it stands out for the presence of its own magnetosphere, which, presumably, arose due to convection (a type of heat transfer when energy is transferred by streams of gas or liquid) in its iron-saturated liquid core.
A little about plasma “rains”. On Earth, where there is an atmosphere, solar radiation is ionized, creating a characteristic glow around the poles. Pictures of “Juno” showed that in Ganymede, devoid of atmosphere, streams of charged particles – in fact, these are plasma “rains” – under the influence of a magnetic field, unhindered rush to the poles, turning ice into a loose mass, while at the equator it has the usual crystalline structure …
NASA hopes that the information received from “Juno” will expand understanding of the evolution of all 79 satellites of Jupiter since their inception and will help in preparing upcoming missions for them, in particular, the European JUICE and the American Europa-Clipper, which should take place, respectively, in 2022 and 2023-25.