For the first time in history, scientists are able to generate hot "superionic ice" that's unlike any other type of ice on Earth.
This bizarre ice is so alien that it's not even naturally occurring on Earth, but it's believed to exist in the depths of Uranus and Neptune.
In a paper published in the journal Nature, scientists explain how they used giant lasers to flash-freeze water and produce superionic ice, taking a snapshot of the rare ice's atomic structure in the process.
Superionic Ice
More than 30 years ago, scientists predicted that the extreme pressures and temperatures of watery giant planets such as Uranus and Neptune could turn water into superionic ice, which is a bizarre state of matter consisting of a solid lattice of oxygen and liquid-like hydrogen.
Scientists from the Lawrence Livermore National Laboratory set out to produce superionic ice and they first found evidence of its existence in 2018.
In the new series of experiments, the team not only generated superionic ice at a temperature of thousands of degrees, but they were also able to observe its microscopic atomic structure. All of it took place in a few billionths of a second.
"We wanted to determine the atomic structure of superionic water," explained Federica Coppari, study co-lead author and LLNL physicist. "But given the extreme conditions at which this elusive state of matter is predicted 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."
The Design
Fortunately, the physicists had a highly innovative design up their sleeve.
Six giant laser beams generated shockwaves of increasing intensity to compress a thin layer of liquid water to extreme pressure and temperature. The conditions were very alien: 100 to 400 gigapascals, which is 1-4 million times the planet's atmospheric pressure, and a temperature of 1,600 to 2,800 Celsius (3,000 to 5,000 degrees Fahrenheit).
Then, to document and observe the atomic structure of the superionic ice, the team shot it with x-rays.
Marius Millot, co-lead author and another LLNL physicist, explains that while they designed the experiments to compress the water and freeze it into ice, they weren't sure if ice crystals could actually develop in the span of the few billionths of a second they could hold the conditions of extreme pressure and temperature the process required.
Analyzing the data, the team found a previously unknown atomic structure for water ice that they called "ice XVIII."
Findings offer potential insight about the internal makeup and evolution of planets like Uranus and Neptune, such as that the superionic ice within Uranus and Neptune has a crystalline lattice, which suggests it doesn't flow like Earth's fluid iron outer core.
"Rather, it's probably better to picture that superionic ice would flow similarly to the Earth's mantle, which is made of solid rock, yet flows and supports large-scale convective motions on the very long geological timescales," Millot said.
