NASA’s Galileo spacecraft took an image of Jupiter’s moon Europa in the summer of 2001. In the colorized version, strange red streaks can be seen, appearing almost like the capillaries feeding a giant eyeball.
These streaks turned out to be a mystery: scientists assumed they were a mixture of sodium chloride salts with water ice, but the chemical signature of these streaks in the spectrometer readings does not matches those of any known salt on Earth – the salts on Europe seem to contain more water.
“Salt and water are very well known in Earth conditions. But beyond that, we’re totally in the dark. And now we have these planetary objects that probably have compounds that are very familiar to us, but in very exotic conditions,” Baptist NewspapersActing Assistant Professor of Earth and Space Sciences at the University of Washington said in a press release. “We have to redo all the basic mineralogical science that people did in the 1800s, but at high pressure and low temperature.”
Journals is one of the authors of a new study published Tuesday in the Proceedings of the National Academy of Sciences who did just that, recreating the high pressure conditions observed in the icy crust of Europe several kilometers thick in a laboratory and measuring how it changed the formation of ice crystals from a mixture of brine . They discovered the first new salty ice-water crystal structures found in more than a century, structures that are likely candidates for the strange salty material at the surface of Europa.
“It has the structure that planetary scientists have been waiting for,” Journals said.
This could help scientists better understand Europa’s potential habitability – the ocean of liquid water believed to exist beneath the moon’s icy crust, in contact with a rocky core and heated by geothermal energy, is one of the places the most promising for the development of extraterrestrial life in the solar system.
Europe is salty
The key discoveries here are two new chemical structures where salts and water form a network held together by hydrogen bonds, called hydrates. They are the first new hydrates discovered since 1847, when, and so far, only the hydrate was first described.
But hydrohalite does not contain much water in its structure, with only two molecules of water for each molecule of salt. The two new hydrates are “hyperhydrated”, one containing 13 molecules of water for each molecule of salt and the other containing 17 molecules of water for each molecule of salt.
The researchers created brines with varying degrees of salt, then subjected them to intense pressures of up to 25,000 Earth atmospheres between two small diamonds, with the diamonds acting as windows to allow viewing through a microscope.
“The pressure just brings the molecules together, so their interaction changes – that’s the main driver of the diversity of crystal structures we found,” Journals said. The crystals, born at high pressure, remained stable when the pressure was lowered to Earth levels, as long as temperatures remained minus 58 degrees Fahrenheit or colder.
“If you have a very brackish lake, say in Antarctica, that could be exposed to these temperatures, this newly discovered hydrate could be present there,” Journals said.
How it could improve the case for life on Europa
Because salt can act as an antifreeze and keep liquid water at cooler temperatures, it can play an important role inside Europa, keeping its underground ocean in a liquid phase. Understanding the forms salt takes on the moon could help scientists interpret the results of upcoming planetary science missions, like NASA’s. European Clipper mission scheduled for launch in 2024, the space agency dragonfly mission to Saturn’s moon Titan scheduled for 2026, and the European Space Agency Explorer of the icy moons of Jupiter, slated for launch in April.
“They are the only planetary bodies, other than Earth, where liquid water is stable on geologic timescales, which is crucial for the emergence and development of life,” Journals said. “They are, in my opinion, the best place in our solar system to discover extraterrestrial life, so we need to study their oceans and exotic interiors to better understand how they formed, evolved and can hold liquid water in them. cold regions of the Sun”. System, so far from the Sun.”