Jupiter’s Europa is seriously salty

Scientists Discover Strange Table Salt Compound on Jupiter's Europa

Scientists Discover Strange Table Salt Compound on Jupiter's Europa

This is potential evidence that sodium chloride, otherwise known as table salt, exists within Europa's subsurface ocean-yet another indication of this moon's potential to support alien life.

Europa, the fourth-biggest moon orbiting gas giant Jupiter, hides a salty, liquid ocean underneath its icy shell and thus, may harbor the ingredients necessary for life. The finding was published by Science Advances on June 12.

Previously, NASA's Voyager and Galileo spacecraft performed flybys of Europa, which led scientists to discover that the moon has a salty liquid water ocean beneath an icy shell. That is, it doesn't exhibit any easily identifiable spectral features at infrared wavelengths.

"For a long time after Galileo, it was thought that magnesium sulfate salts might be the most important".

"The Galileo spacecraft didn't have a visible spectrometer".

That all changed when new, higher spectral resolution data from the W. M. Keck Observatory suggested that the researchers weren't actually seeing magnesium sulfates. Most of the sulfate salts considered previously possess distinct absorptions, which serve as fingerprints for compounds, that should have been visible in the higher-quality Keck data. But, the spectra of these areas "expected to reflect the internal composition lacked any of the characteristic sulfate absorptions", according to the study.

Researchers scanned Europa's surface with the Hubble, as well as infrared light, which revealed traces of sodium chloride.

"The next step is the Europa Clipper, which will fly by Europa a bunch of times and [make] many multiple different kinds of measurements: images of the geological structures on the surface, look for spectral signatures to identify the "brown gunk" that seems to be coming out of the cracks from the ocean below, measure magnetic and particle signatures of the electrical currents that flow in the ocean under the ice-and use the radar to estimate the ice thickness, if possible", she said. Sodium chloride turned a yellow shade that was similar to Europa's geologically young area, also known as "Tara Regio".

Scientists confirmed that it was sodium chloride on Europa's surface by obtaining four observations of the moon from the Hubble Space Telescope from May to August in 2017. "Before irradiation, you can't tell it's there, but after irradiation, the color jumps right out at you", Hand said.

By taking a close look with NASA's Hubble Space Telescope, the research team was able to identify a distinct absorption in the visible spectrum at 450 nanometers, which matched the irradiated salt precisely, confirming that the yellow color of Tara Regio reflected the presence of irradiated sodium chloride on the surface.

"Specifically we used an instrument called the Space Telescope Imaging Spectrograph (STIS)".

That's enough to reassess just what Europa's hidden ocean is made of, say the scientists behind the new study, and the sort of life it might potentially be harbouring.

A subterranean ocean thought to be beneath the surface of Jupiter's moon Europa could be strikingly similar to the seas here on Earth.

"Magnesium sulfate would simply have leached into the ocean from rocks on the ocean floor, but sodium chloride may indicate the ocean floor is hydrothermally active", said Samantha Trumbo, lead study author and California Institute of Technology graduate student, in a statement.

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