Salt and organic matter found on Jupiter's moon

Ganymede is the largest moon in the Solar System, larger than Mercury. It is one of the four Galilean moons of Jupiter, discovered by Galileo Galilei in the early 17th century.

The four Galilean moons also include Calisto, Europa and Io. Of these, Europa is of particular interest to NASA because of the series of signs of potential life that have been continuously revealed. A direct life-hunting spacecraft called Europa Clipper is scheduled to depart in October 2024.

One of the most remarkable signs that Europa has revealed is organic compounds contained in the steam that rises from its subsurface ocean. Ganymede has just done the same.

Accordingly, the US National Aeronautics and Space Administration (NASA) announced on October 31 that the Juno spacecraft had for the first time discovered mineral salts and organic compounds on the surface of Jupiter's moon Ganymede.

The discovery suggests that underground brines are reaching the icy world ’s crust, according to NASA. The data was captured by the Jovian Infrared Auroral Mapper (JIRAM) spectrometer on board Juno as it flew close to Jupiter’s icy moon.

On June 7, 2021, Juno flew past Ganymede at a minimum altitude of 1,046 km. Shortly after its closest approach, the JIRAM instrument obtained infrared images and infrared spectra of the surface of the largest satellite in the Solar System.

The images achieved unprecedented spatial resolution for infrared spectroscopy. Using these data, scientists were able to detect and analyze unique spectral features of materials other than water, including hydrated salts, ammonium chloride, sodium bicarbonate, and possibly aliphatic aldehydes, according to NASA.

Scientists concluded that the salts and organic compounds suggested either hydrothermal activity deep beneath Ganymede's icy surface or interaction between the subsurface ocean and rocks deep within the planet. Of these, hydrothermal activity is the most likely hypothesis, supported by several previous studies.

Hydrothermal activity is sustained by hydrothermal vents on the ocean floor that Earth itself possesses.

Previous studies have shown that these same hydrothermal systems seeded life in Earth’s early oceans, providing heat and nutrients to what was once a cold, dead ocean floor. So that’s more good news for Ganymede.

Previously, some other studies also showed that the ocean below Ganymede is a warm world, suitable for life.

Even though the space around Jupiter is cold, the sheer size of the planet and its moons creates powerful tidal interactions, enough to "heat" underground oceans on its moons - including those of Europa, Ganymede and possibly Calisto.

While less promising than Europa, the new discovery adds to the evidence that Ganymede is a world worth exploring in the search for alien life. Some scientists also believe that Calisto has promise. Io, on the other hand, is too volcanically active to be considered habitable.

Minh Hoa (reported by Tuoi Tre, Nguoi Lao Dong)

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