While Europa and Enceladus have garnered attention for their subterranean oceans and potential for life, other frozen worlds have been left in the shadows, but Jupiter’s mysterious moon Ganymede is now making headlines. Decorating.
Although Ganymede has not yet been observed spewing plumes of water vapor like Saturn’s moon Enceladus, Jupiter’s largest moon most likely harbors a huge ocean of salt water. hubble observation It suggests that the ocean, thought to lie beneath 150 km (95 miles) of ice, may be up to 100 km (60 miles) deep. This is 10 times deeper than Earth’s oceans.
Ganymede is in a temporary state because NASA’s Juno mission observed salts and organic compounds on Ganymede’s surface, possibly from the ocean beneath its icy crust. Although Juno’s observations cannot provide conclusive evidence that there is an ocean on this moon that makes Earth look like a kiddie pool, Juno’s findings suggest that salts and other chemicals may reach the outside of Ganymede. This is the strongest evidence yet that this is the case.
deep sea
It is already known that Ganymede’s surface is made of water ice. Juno’s JIRAM (Jupiter Infrared Aurora Mapper) instrument used its infrared vision to identify materials including hydrated salts, ammonia salts, sodium bicarbonate, hydrated silica, and possible . aliphatic aldehyde, potentially allowing the construction of more complex organic compounds. Hydrated salt (sodium chloride hydrate) may hint at an ocean of salt water beneath the surface ice. Juno mission scientists believe that the ammonia salts (ammonium chloride) found on the surface could mean that as Ganymede formed, material cold enough for ammonia to condense somehow accumulated. I think there is. Carbonates can be carbon dioxide-rich leftover ice.
“The composition and spatial distribution of these salts and organic matter suggest that their origin is endogenous, due to extrusion of subsurface brine, and that their chemistry is related to the interaction of water and rocks within Ganymede. ,” the scientists wrote in a study recently published in Nature.
Endogenous substances originate from the interior of the moon, planets, and other celestial bodies, while extrinsic substances originate from the surface. If the salts and organic matter found are truly endogenous, that means they somehow came up from deep within Ganymede. They may have traveled through water oozing from cracks in the earth’s surface, rather than being emitted in the form of steam plumes like on Enceladus.
JIRAM did not find any exogenous compounds such as hydrogen peroxide or hydrated sulfuric acid. All of these were found on the surface of Europa, another frozen Jupiter world, but they were detected near Ganymede’s poles. previous research. The absence of exogenous compounds in these salty sediments (at least based on what JIRAM was able to observe) may be evidence that the compounds found come from salty oceans.
reach the surface
It is still unclear whether the compounds discovered by JIRAM actually occur deep inside or near the surface. Despite the lack of conclusive evidence for its oceans, Juneau scientists also acknowledge that organic matter and salts may have somehow originated in shallower layers of the Earth’s crust. Ganymede’s crust is much thicker than Europa’s, meaning it is more difficult for material from the underground ocean to penetrate and reach its crust.
connection established Between aliphatic aldehydes and liquid water activity, at least on Earth. Other researchers have also observed what they believe to be signs of water vapor plumes erupting from Enceladus. If so, Enceladus’ vapors would also contain some of the same salts found on Ganymede’s surface, and these salts are thought to be endogenous, strengthening the case for a subsurface marine origin. It will be done. These are thought to result from the interaction of liquid water with rocks, especially silicate rocks.
The discovery of organic matter and aliphatic aldehydes on Ganymede inevitably raises another question: Does Ganymede have what it takes to sustain life? Maybe. Aliphatic aldehydes are found in certain carbonaceous meteorites that have fallen to Earth and are precursors to carboxylic acids and amino acids. Alien seekers shouldn’t get too excited about this. Organic matter exists everywhere in the universe, so the presence of organic matter on Ganymede is not that surprising. Still, it can continue to fire the imaginations of those who want to believe.
Natural Astronomy, 2023. DOI: 10.1038/s41550-023-02107-5