When the Europa Clipper mission arrives on Jupiter's distant Moon, it will look for sources of water that are thought to exist beneath the surface in the form of ice. Scientists have discovered a new type of ice that could exist in these distant worlds ahead of its launch.
Scientists studying the properties of high-pressure water have discovered a new phase known as Ice-VIIt, which is an intermediate and tetragonal phase between cubic phase, Ice-VII, and Ice-X. They believe it is unlikely that they will find this unique phase anywhere on Earth's surface, but it could be a common ingredient in the Earth's mantle as well as large moons and water-rich planets beyond our solar system.
The study, which was published in Physical Review B, established a new method for measuring the properties of water under high pressure. The team, led by researchers from the University of Nevada Las Vegas' Department of Physics and Astronomy, squeezed the water sample between the tips of two opposite-facing diamonds, causing it to freeze into several jumbled ice crystals.
Findings of Study:
According to the university, by applying a small amount of force to the diamonds, the researchers were able to recreate pressures as high as those found at the Earth's core.
The ice was then heated with a laser, which temporarily melted it before quickly forming a powder-like collection of tiny crystals. "The team observed the water ice make the transition from a known cubic phase, Ice-VII, to the newly discovered intermediate by incrementally increasing the pressure and periodically blasting it with the laser beam," the team said in a statement.
Scientists drove the oxygen and hydrogen atoms into a variety of different arrangements by squeezing the water sample between these diamonds, including the newly discovered arrangement, Ice-VIIt. The study not only contributed to the discovery of a new ice phase, but it also demonstrated that the transition to Ice-X occurred at pressures nearly three times lower than previously thought at 300,000 atmospheres instead of 1 million.
The research, led by Zach Grande, a Ph.D. student at the University of Nevada Las Vegas, contributes to a better understanding of the behaviour of high-pressure water that may exist in the interiors of distant planets.
"Zach's research has shown that the transition to an ionic state occurs at much lower pressures than previously thought." It's the missing piece, and the most precise measurements ever taken on the water under these conditions," said physicist Ashkan Salamat.
The new research could aid astronomers in better understanding the composition of exoplanets. Researchers hypothesise that the Ice-VIIt phase of ice could exist in abundance in the crust and upper mantle of expected water-rich planets beyond our solar system, implying that they could support life.
