New type of salty ice may exist on alien ocean moons

(CNN) The mysterious red streaks crossing the surface of Jupiter’s moon Europa may be the result of a newly discovered type of salty ice.

Europa has long fascinated scientists because the moon has a subsurface ocean under a thick shell of ice. Plumes of water have been known to erupt from cracks in the ice shell and release the contents of the moon foreign ocean into space.

Ocean worlds like Europa are the best bet for finding evidence of extraterrestrial life, according to scientists.

The chemical signature of Europa’s red streaks on its surface, thought to be a frozen mixture of water and salts, appeared unusual because it did not match any known substance on Earth.

Researchers determined i 2019 that the yellow parts of Europa’s surface were caused by the presence of sodium chloride – better known as table salt.

To gain more insight into Europa, which will be visited by the European Space Agency’s JUICE (short for Jupiter Icy Moons Explorer) and NASA’s Europa Clipper mission over the next couple of years, scientists worked to recreate lunar conditions in a laboratory.

The research team found that combining water, table salt, cold temperatures and high pressure resulted in a new type of solid crystal – and this substance may exist on Europa’s surface and at the bottom of the hidden sea.

Jupiter’s moon Europa hosts a subsurface ocean under a thick shell of ice, which bears a series of red streaks.

“It is rare today to have fundamental discoveries in science,” lead study author Baptiste Journaux, an acting assistant professor of earth and space sciences at the University of Washington, said in a statement.

“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. We have to redo all the basic mineralogical science that people did in the 19th century, but at high pressure and low temperature. It’s an exciting time.”

Water and salts create a hydrate, a rigid icy lattice supported by hydrogen bonds, in cold temperatures.

Unusual compound with two salt molecules

Prior to this study, the prevailing scientific wisdom stood there was just one hydrate for sodium chloride, created from two water molecules and one salt molecule.

After the study experiment, the researchers discovered two new hydrates – one with two salt molecules for every 17 water molecules, and another with one salt molecule for every 13 molecules.

“It has the structure that planetary scientists have been waiting for,” Journaux said.

A study detailing the findings was published Monday in the Proceedings of the National Academy of Sciences.

The hydrates could explain why the chemical signatures of Jupiter’s ocean worlds are so “watery,” according to the study.

The researchers began the experiment by compressing a small amount of salt water between two diamonds, each about the size of a grain of sand. The water was pressurized to 25,000 times standard atmospheric pressure.

The team was able to observe this process through a microscope.

“We were trying to measure how adding salt would change the amount of ice we could get, since salt acts as an antifreeze,” Baptiste said. “Surprisingly, when we applied pressure, what we saw was that these crystals that we hadn’t expected started to grow. It was a very serendipitous discovery.”

Frozen, high pressure environment

Jupiter’s ocean moons likely experience similar conditions with frigid temperatures and high pressure.

The ice shell that makes up Europa’s surface is estimated to be between 10 and 15 miles (16 and 24 kilometers) thick, and the ocean it probably sits on top of is estimated to be 40 to 100 miles (64 to 161 kilometers) deep.

“Pressure just brings the molecules closer together, so their interaction changes – that’s the main driver of diversity in the crystal structures we found,” Journaux said.

Of the two hydrates, one remained stable even after the pressure was released.

“We determined that it remains stable at standard pressures up to around minus 50 Celsius (minus 58 degrees Fahrenheit). So if you have a very salty lake, say in Antarctica, that can be exposed to these temperatures, this newly discovered hydrate could be be there,” Journaux said.

Understanding the chemistry found in ocean worlds like Europa will allow scientists to better understand the data collected by missions like JUICE and Europa Clipper in the future.

“These are the only planetary bodies, other than Earth, where liquid water is stable on geological time scales, which is essential for the emergence and development of life,” Journaux said.

“They are, in my opinion, the best place in our solar system to detect extraterrestrial life, so we need to study their exotic oceans and interiors to better understand how they formed, evolved and can retain liquid water in cold regions of the solar system. so far away from the sun.”

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