Traces Of Jovian Plasma Were Found On The Surface Of Ganymede
In the first images of the North pole of Jupiter's moon Ganymede taken by the Juno interplanetary vehicle, astronomers found traces of "plasma bombardment" of its surface. In addition to the images, the probe measured the satellite's magnetic field for the first time, according to NASA's Jet Propulsion Laboratory (JPL).
"Data from the JIRAM instrument indicates that the ice that surrounds the North pole of Ganymede has changed its structure due to the large amount of plasma that got there. We first learned about this and studied this phenomenon in detail thanks to the fact that Juno photographed this region, " said one of the specialists of the Juno mission, an astronomer from the National astrophysical Institute of Italy, Alessandro Mura.
Ganymede, along with three other moons of Jupiter – Io, Callisto, and Europa – was discovered by Galileo Galilei in the early 17th century. The main feature of this celestial body is that it is the only satellite of the Solar system with its own magnetic field.
The Juno probe, which has been studying Jupiter since 2016, came close to Ganymede during one of its flights around the planet, flying at a distance of about 100 thousand km from its surface. During this flyby, mission specialists turned the probe's instruments toward the satellite to explore Ganymede's North pole and its magnetic field.
Detailed photos of this region and data on the concentration of various molecules above it confirmed that Ganymede does have its own magnetic field. In particular, this is indicated by traces of plasma produced by the magnetosphere of Jupiter. The satellite's magnetic field captures it and directs it to the vicinity of the poles.
There, plasma falls on the surface of the water ice that Ganymede is partly made of, and changes its structure, making it more amorphous; this is indicated by images of the JIRAM infrared camera, which is installed on Juno.
Scientists hope that analyzing this data will help them assess the power of Ganymede's magnetic field and learn other data that will help future missions better prepare to study Jupiter's moons. These missions include the European JUICE (Jupiter Icy Moon Explorer), which is scheduled to launch in June 2022, and the American Europa-Clipper, which is scheduled to launch in 2023-2025.