A brand-new kind of salty ice could be the cause of the baffling red streaks that crisscross Europa’s surface.
Scientists have long been intrigued by Europa due to the moon’s subsurface ocean and thick ice shell. Cracks in the ice shell have been known to burst, releasing water plumes and the alien ocean’s contents into space.
Scientists say that ocean worlds like Europa are the best place to look for evidence of life elsewhere in the universe.
Because it did not match any known substance on Earth, the chemical signature of Europa’s red streaks on the surface, which was thought to be a frozen mixture of water and salts, appeared unusual.
In 2019, researchers discovered that the presence of sodium chloride, more commonly known as table salt, was the cause of the yellow areas on Europa’s surface.
The European Space Agency’s JUICE (short for the Jupiter Icy Moons Explorer) mission and NASA’s Europa Clipper mission will both visit Europa within the next few years. To gain further insight into Europa, scientists recreated the conditions of the moon in a laboratory.
A new kind of solid crystal was created when water, table salt, cold temperatures, and high pressure were combined, according to the team’s findings. This substance could be on Europa’s surface or in its hidden ocean at the bottom.
In a statement, lead study author Baptiste Journaux, an acting assistant professor of Earth and space sciences at the University of Washington, said, “It’s rare nowadays to have fundamental discoveries in science.”
“Water and salt are well-known Earth conditions.” Beyond that, however, we are completely unaware. And now we have these planets with compounds that are probably very familiar to us, but they are in very strange conditions. All fundamental mineralogical research from the 1800s must be replicated at high pressure and low temperature. It’s a thrilling time.
In cold temperatures, salts and water form a hydrate, a rigid icy lattice supported by hydrogen bonds.
Strange substance with two salt molecules
Prior to this study, conventional wisdom held that sodium chloride only had one hydrate, made up of one salt molecule and two water molecules.
The study experiment resulted in the discovery of two brand-new hydrates: one with one salt molecule for every 13 molecules and one with two salt molecules for every 17 water molecules.
Journaux stated, “It has the structure that planetary scientists have been waiting for.”
The findings were published in the Proceedings of the National Academy of Sciences on Monday in a study.
According to the study, the “watery” chemical signatures of Jupiter’s ocean worlds could be explained by the hydrates.
The specialists started their investigation just barely of pungent water between two precious stones that were each about the size of a grain of sand. Up to 25,000 times the pressure of the atmosphere, the water was squeezed.
Using a microscope, the team was able to observe this process.
Baptiste stated, “We were trying to measure how adding salt, which acts as an antifreeze, would change the amount of ice we could get.” Surprisingly, we observed the growth of these unexpected crystals when we increased the pressure. It was an extremely happy accident.
Frozen, high-pressure environment
The ocean moons of Jupiter probably have similar conditions, with high pressure and icy temperatures.
Europa’s ice shell is thought to be between 10 and 15 miles (16 and 24 kilometers) thick, and the ocean it probably sits on is thought to be between 40 and 100 miles (64 and 161 kilometers) deep.
According to Journaux, “Pressure just gets the molecules closer together, so their interaction changes” is the primary cause of the variety found in the crystal structures.
After the pressure was released, one of the two hydrates remained stable.
“We discovered that it remains stable at standard pressure up to approximately minus 50 Celsius (minus 58 Fahrenheit).” According to Journaux, this newly discovered hydrate could be present in a very briny lake in Antarctica, for example, that is exposed to these temperatures.
Scientists will be able to better comprehend the data gathered by missions like Europa Clipper and JUICE in the future if they have a solid understanding of the chemistry that exists on ocean worlds like Europa.
According to Journaux, “these are the only planets, other than Earth, where liquid water is stable at geological timescales, which is crucial for the emergence and development of life.”
“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 because they are, in my opinion, the best place in our solar system to discover extraterrestrial life.”