Using data from the Jovian Infrared Auroral Mapper (JIRAM) instrument aboard NASA’s Juno spacecraft, the researchers produced a new infrared map of Jupiter Ganymede’s moon, combining data from three overflights, including including its last approach on July 20, 2021.
The Juno spacecraft approached within 50,109 km (31,136 miles) of Ganymede on July 20, 2021.
On previous overflights on June 7, 2021 and December 26, 2019, the orbiter approached 1,046 km (650 miles) and 100,000 km (62,000 miles), respectively.
The three observation geometries allowed the JIRAM instrument to see for the first time the north polar region of the Moon, as well as to compare the diversity of composition between low and high latitudes.
âGanymede is larger than the planet Mercury, but just about everything we explore during this mission to Jupiter is on a monumental scale,â said Juno principal investigator Dr. Scott Bolton, a researcher at Southwest Research. Institute.
“The infrared and other data collected by Juno during the flyby contains fundamental clues to understanding the evolution of Jupiter’s 79 moons from their formation until today.”
Ganymede is the only moon in the solar system to have its own magnetic field.
On Earth, the magnetic field allows the Sun’s plasma to enter our atmosphere and create auroras.
Because Ganymede has no atmosphere to hinder their progress, the surface of its poles is constantly bombarded by plasma from Jupiter’s gigantic magnetosphere.
The bombardment has a dramatic effect on the ice of Ganymede.
“We found the high latitudes of Ganymede dominated by water ice, with a fine grain size, which is the result of intense charged particle bombardment,” said Juno co-investigator Dr. Alessandro Mura, researcher at the Italian National Institute of Astrophysics.
âConversely, low latitudes are protected by the moon’s magnetic field and contain more of its original chemical composition, including constituents other than water ice such as salts and organic matter. . “
âIt is extremely important to characterize the unique properties of these icy regions to better understand the spatial weathering processes undergone by the surface. “