NASA's Juno observes mineral salts, organic treasures on Jupiter’s moon Ganymede

NASA's Juno mission has made a significant observation of mineral salts and organic compounds on the surface of Ganymede, Jupiter's largest moon. This data was gathered by the Jovian InfraRed Auroral Mapper (JIRAM) spectrometer during a close flyby of Ganymede. The findings are crucial as these observations will now be able to throw light on Ganymede's origin and its deep-ocean composition.

The results of the observation were published in the journal Nature Astronomy on October 30.

Ganymede is even larger than the planet Mercury. This moon, one among more than 80 moons of the planet Jupiter, has attracted scientific interest due to its vast internal ocean hidden beneath an icy crust.

The observation is a breakthrough for scientists as previous observations from NASA's Galileo spacecraft, the Hubble Space Telescope, and the European Southern Observatory's Very Large Telescope had only hinted at the presence of salts and organic compounds. At the time, the spatial resolution of those observations was insufficient to draw definitive conclusions. 

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Juno flies over Jupiter's moon, Ganymede

On June 7, 2021, the Juno spacecraft flew over Ganymede at an altitude of 650 miles.

The JIRAM instrument captured infrared images and spectra of the moon's surface. JIRAM, built by the Italian Space Agency, was originally designed to study Jupiter's atmosphere but has also been used to explore the surfaces of Jupiter's Galilean moons - Io, Europa, Ganymede, and Callisto.

The JIRAM data collected during the flyby achieved a remarkable spatial resolution for infrared spectroscopy which exceeded 0.62 miles per pixel.

Using this data, Juno scientists identified and analysed unique spectral features of non-water-ice materials, including hydrated sodium chloride, ammonium chloride, sodium bicarbonate, and possibly aliphatic aldehydes.

Federico Tosi, a Juno co-investigator from Italy’s National Institute for Astrophysics in Rome and lead author of the paper in a statement said, “The presence of ammoniated salts suggests that Ganymede may have accumulated materials cold enough to condense ammonia during its formation."

“The carbonate salts could be remnants of carbon dioxide-rich ices," Tosi added. 

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Abundance of salts and organics

During the June 2021 flyby, JIRAM identified the greatest abundance of salts and organics in the dark and bright terrains at latitudes protected by Ganymede's magnetic field.

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Scott Bolton, Juno’s principal investigator from the Southwest Research Institute in San Antonio said, “This suggests we are seeing the remnants of a deep ocean brine that reached the surface of this frozen world.”

(With inputs from agencies)