Ganymede moon has a huge internal ocean and salty surface

NASA’s Juno spacecraft has identified mineral salts and organic compounds on Ganymede, the largest moon of Jupiter. This significant find comes from the high-resolution data gathered by the Jovian InfraRed Auroral Mapper (JIRAM) spectrometer onboard Juno during its close flyby of the moon.

Ganymede: Icy behemoth moon

Ganymede is not just another moon in our solar system. It’s larger than the planet Mercury, making it the largest moon of Jupiter, and has captivated the scientific community for decades. One of the primary reasons for its allure is the vast ocean believed to be ensconced beneath its icy surface.

Past endeavors, notably by NASA’s Galileo spacecraft, the Hubble Space Telescope, and the European Southern Observatory’s Very Large Telescope, have suggested the possibility of salts and organics on Ganymede. However, the resolution of these observations wasn’t sufficiently detailed for conclusive results.

Remarkable Juno flyby

On June 7, 2021, the Juno spacecraft made history when it soared over Ganymede at a mere distance of 650 miles (1,046 kilometers). Armed with the JIRAM spectrometer — a marvel of engineering constructed by Italy’s Agenzia Spaziale Italiana — the spacecraft secured infrared images and spectra of Ganymede’s surface.

Originally, JIRAM’s primary objective was to study infrared light radiating from deep within Jupiter. This would allow scientists to analyze the atmospheric conditions 30 to 45 miles (50 to 70 kilometers) beneath the gas giant’s thick clouds. However, JIRAM has also provided insights into the terrains of the Galilean moons, named in honor of their discoverer, Galileo.

The data Juno obtained from its Ganymede flyby was unparalleled in its precision. It achieved an impressive resolution of better than 0.62 miles (1 kilometer) per pixel. This allowed scientists to distinguish and investigate the spectral characteristics of non-water-ice materials on the moon’s surface.

Ganymede: What this means for the Jovian moon

According to the data, the detected materials include hydrated sodium chloride, ammonium chloride, sodium bicarbonate, and possibly aliphatic aldehydes. Federico Tosi, a key investigator with Juno and lead author of the paper documenting these findings, shed light on their implications.

He mentioned, “The presence of ammoniated salts suggests that Ganymede may have accumulated materials cold enough to condense ammonia during its formation.” Tosi further elaborated that the carbonate salts found might be the remnants of carbon dioxide-rich ices.

Furthermore, Ganymede’s unique magnetic field shields parts of its surface from Jupiter’s intense magnetic field. This protection extends up to a latitude of about 40 degrees.

Scott Bolton is Juno’s principal investigator. He pointed out, “We found the greatest abundance of salts and organics in the dark and bright terrains at latitudes protected by the magnetic field.” Bolton added that the evidence might suggest remnants of a deep-sea brine that once graced the moon’s surface.

Juno’s journey continues

But Juno’s mission isn’t limited to Ganymede. The spacecraft also ventured close to Europa, another of Jupiter’s moons with a suspected subsurface ocean.

This exploration took place in October 2021 and September 2022. Up next on Juno’s itinerary is a rendezvous with Io, known for its volcanic activity. A close approach, bringing the spacecraft within 932 miles (1,500 kilometers) of Io, is scheduled for Dec. 30.

As Juno continues its journey, shedding light on the mysteries of our solar system, the world eagerly awaits its next revelation.

More about Jupiter’s moon Ganymede

Ganymede, the colossal moon of Jupiter, holds a prominent position in the study of our solar system. As NASA delves deeper into its mysteries, we come to recognize the importance and uniqueness of this icy moon.

Overview of the Jovian moon, Ganymede

Ganymede is not just another celestial body orbiting Jupiter. It’s the largest moon in our entire solar system, even surpassing the planet Mercury in size. Discovered by Galileo Galilei in 1610, Ganymede has been a subject of intrigue for centuries.

Several key characteristics set Ganymede apart.

Water-ice surface

Ganymede possesses a water-ice surface that conceals a vast internal ocean, possibly containing more than twice the water volume of Earth.

Magnetic field

Unlike most moons, Ganymede has its own magnetic field. This phenomenon is rare among celestial satellites and offers rich grounds for research.

Thin atmosphere

Ganymede’s atmosphere, predominantly composed of oxygen, is extremely thin and incapable of supporting human life.

NASA’s exploration

NASA has actively pursued the study of Ganymede through various missions:

• Pioneer 10 and 11: These spacecrafts were the first to fly by Jupiter and its moons, including Ganymede, in the early 1970s, providing initial close-up images.
  
• Voyager 1 and 2: Launched in the late 1970s, these missions returned detailed images and data on Ganymede’s surface and environment.
  
• Galileo: Arriving at Jupiter in the 1990s, the Galileo spacecraft provided deeper insights into Ganymede, confirming the existence of its magnetic field and suggesting the presence of a subsurface ocean.

Future prospects for the Ganymede moon

While Ganymede continues to spark curiosity, future missions aim to probe its potential subsurface ocean and its capacity to harbor life. As NASA and other space agencies set their sights on this intriguing moon, Ganymede promises to remain a focal point in the exploration of our solar system.

More about the Juno Mission

Launched by NASA, the Juno spacecraft is a marvel of modern engineering, designed specifically to study Jupiter’s atmosphere, magnetosphere, and its deep interior.

Juno’s launch

NASA launched the Juno spacecraft on August 5, 2011, with the primary mission to closely investigate the gas giant, Jupiter. Upon reaching its destination in July 2016, Juno entered a polar orbit around Jupiter, making it the first spacecraft to do so.

Mission objectives

The primary goals of Juno are manifold:

Atmospheric analysis

Juno aims to measure the composition, temperature, and motion of Jupiter’s atmosphere. This helps in understanding how the planet’s atmospheric dynamics operate below the cloud tops.

Magnetic and gravitational field measurements

The spacecraft is equipped to map Jupiter’s magnetic and gravitational fields, revealing the planet’s internal structure.

Magnetosphere study

Juno investigates the polar magnetosphere and the origin of Jupiter’s powerful auroras.

Technological marvels aboard

Juno houses a suite of scientific instruments. Among them:

• JIRAM (Jovian InfraRed Auroral Mapper): Captures infrared images, providing a deeper look into Jupiter’s atmosphere and studying its auroras.
  
• MWR (Microwave Radiometer): Peers beneath Jupiter’s dense cloud cover to analyze its composition and thermal structure.
  
• MAG (Magnetometer): Measures the planet’s magnetosphere, key to understanding its magnetic field.

Juno’s legacy

Beyond its scientific observations, Juno sends back breathtaking images of Jupiter and its moons. The Jovian images offer a fresh perspective on the planet’s storms, bands, and the iconic Great Red Spot. In addition, as mentioned earlier in this article, observations of the Ganymede moon revealed many important discoveries about the ocean moon.

These visuals not only intrigue scientists but also captivate the general public, fostering a deeper appreciation for space exploration. As Juno continues its mission, it promises to unlock more secrets of Jupiter, further enriching our understanding of the universe.

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