Scientists have used high-energy lasers to create a new phase of ice unlike any other view on Earth, but which could exist deep between Neptune and Uranus.
The structure of the water allows to freeze in many crystalline forms (including ice-IX, which does not share the same properties as Ice-IX by Kurt Vonnegut Cat & # 39; s Cradle). Perhaps one of the strangest forms is supersonic ice, where hydrogen atoms race around like a liquid through an oxygen-only solid crystal. Supersonic ice could be important to understand how the giant ice planets evolved. With the help of X-rays and lasers, scientists have recently been able to produce and measure this ice in the laboratory.
The researchers first predicted the existence of superionic ice in 1988 and were the first to see evidence of its existence in 2018. New methods have allowed scientists to actually observe its atomic structure.
Scientists squeezed water molecules between a pair of diamonds, then fired the sample with six high-power laser beams in a specialized 15 nanosecond sequence using the Omega Laser Laser Energetics University of Rochester. . This produces shock waves between the diamonds, compressing the water molecules to pressures similar to those at the center of the Earth and temperatures about half those of the earth's core. (One might think that ice should be cold, but matter is sensitive to both temperature and pressure, which means that at very high pressures, water can turn into ice at temperatures that you would expect to be a liquid or a gas. Immediately after the laser pulse, they shoot the sample with X-rays, which allows them to measure the structure of what they have produced.The biggest challenge was the measurement of the sample fairly quickly after creating the ice to generate an unambiguous tracking signature.
"Given the extreme conditions in which this elusive state of matter is expected to be stable, compressing water to such pressures and temperatures and simultaneously taking snapshots of the atomic structure was an extremely difficult task, which required an innovative experimental design ", wrote the author Federica Coppari said in a press release from the Lawrence Livermore National Laboratory.
And their efforts have been successful, Coppari said. There has been other evidence pointing to the existence of this superionic ice. But X-ray diffraction measurements are crucial confirmation. The team proposed to name their ice XVIII.
"This study brings the last missing piece to the puzzle concerning the existence of superionic water ice, 30 years after the original prediction," the authors write in the study published in Nature.
Supersonic ice is more than just a curiosity. "We think it is the bulk of the mass of Uranus and Neptune," Jonathan Fortney, director of the Other Worlds Laboratory at the University of California, Santa Cruz, told Gizmodo. If these planets are filled with this strange form of ice, scientists may need to rethink their patterns of how heat flows through these worlds and how they cool over time.
The researchers still hope to perform measurements at higher temperatures and pressures to completely find out the nature of this ice and to understand the pressures to which the ice takes this superionic form.
Our daily experiences are limited to the temperatures and pressures that are common here on Earth. It is easy to forget how many wild states of matter with strange properties could exist in other realms.
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