NASA's Juno spacecraft has imaged Ganymed, Jupiter's largest moon, and captured images that show how its unusual magnetic field affects the ice at its poles.
Juno passed Ganymede on December 26, 2019, and his path took him over the top of the never-mapped North Pole of the Moon. The Juno team knew that this would be a rare opportunity to see the moon up close. So they prepared for it by turning the vehicle so that its instruments were pointed at the surface of the moon.
Juno came just 62,000 miles from Ganymede and used his JIR (Jovian Infrared Auroral Mapper) to collect 300 infrared images of the lunar surface that were used to create the infrared map of the northern part of the moon.
These images, taken by the JIRAM instrument on board NASA's Juno spacecraft on December 26, 2019, provide the first infrared map of Ganymede's northern border. Frozen water molecules, which were detected at both poles, have no significant order in their arrangement and have a different infrared signature than ice at the equator. NASA / JPL-Caltech / SwRI / ASI / INAF / JIRAM
These pictures show activities on Ganymede, which has no atmosphere, but like Earth a magnetic field. This magnetic field interacts with energetic particles that are emitted by the sun and called plasma. These are directed to the poles of the moon and hit the ice there.
"The JIRAM data show that the ice on and around Ganymede's North Pole has been altered by the precipitation of plasma," said Alessandro Mura, a Juno-Co-investigator at the National Institute for Astrophysics in Rome, in a statement. "It is a phenomenon that we first got to know with Juno because we can see the North Pole in its entirety."
The JIRAM instrument used to take these images can use infrared to look through Jupiter's layer of clouds and see 30 to 45 miles below the clouds, but it can also be used to study Jupiter's moons, including Io, Europa and Callisto as, and Ganymede .
"These data are another example of the great science Juno is capable of observing the Jupiter moons," said Giuseppe Sindoni, program manager of the Italian space agency's JIRAM instrument, in the statement.
This work paves the way for the European Space Agency's JUpiter ICy moons Explorer (JUICE) mission, which is slated to visit these moons in 2030 after its launch in 2022.