It is very difficult for me to believe, but the Juno mission is celebrating its tenth anniversary. The spacecraft was launched on August 5, 2011, from Cape Canaveral Air Force Station and traveled 2,800 million kilometers over five years to reach Jupiter on July 4, 2016. Since then, Juno has orbited Jupiter 35 times and collected nearly three terabits of data. The mission was recently given an extension and now has another 42 orbits to perform, including flybys of the Galilean moons Ganymede, Europa, and Io.

And today, we have a brand new infrared image of Ganymede taken from the most recent of these flybys. Captured with the Jovian Infrared Auroral Mapper, or JIRAM, instrument, this image brings us new information about the icy moon’s shell and the composition of the liquid ocean underneath. As a reminder, Ganymede is the only moon in our solar system to have its own magnetic field, and that field allows for charged particles from the Sun to create aurorae. Additionally, Jupiter constantly bombards Ganymede with plasma from Jupiter’s magnetosphere. All of these incoming particles can affect the ice on Ganymede.

Co-investigator Alessandro Mura explains: We found Ganymede’s high latitudes dominated by water ice, with fine grain size, which is the result of the intense bombardment of charged particles. Conversely, low latitudes are shielded by the moon’s magnetic field and contain more of its original chemical composition, most notably of non-water-ice constituents such as salts and organics. It is extremely important to characterize the unique properties of these icy regions to better understand the space-weathering processes that the surface undergoes.

More Information

NASA JPL press release