Tuesday, June 26, 2018 by Edsel Cook
Imagine ice that is simultaneously a solid and a liquid, has 60 times the density of normal ice, and capable of forming on the burning surface of the sun. It is called “superionic ice,” an article in Space.com states, and California-based researchers have just created it.
This previously theoretical form of ice was first conceived 30 years ago. It is believed to exist deep within the highly pressurized atmospheres of Uranus and Neptune.
The extreme heat and pressure conditions within those two gas giants are able to bring out a strange phase in water, where the compound to act like a solid and a liquid at the same time. During the superionic phase, hydrogen ions can flow like a liquid within a solid lattice of oxygen crystals.
A Lawrence Livermore National Laboratory (LLNL) team led by Marius Millot was responsible for creating superionic ice for the first time. Millot served as the lead author of the study paper, which was recently published in the scientific journal Nature Physics. (Related: Uranus smells, says scientist, who finds that the planet’s upper atmosphere is composed of hydrogen sulfide.)
He and his researchers started out by compressing water into cubic crystalline ice. Diamond anvil cells applied 25,000 times the normal atmospheric pressure on Earth on water.
The next step was applying sharp shocks to the pressurized water using as many as six laser beams for each crystal structure. This shock compression added heat to the system while also increasing the already immense air pressure on the cells.
Compressing the water beforehand reduced the need for shock-heating. In turn, the decreased amounts of shock-compression allowed the LLNL researchers to make much colder ice.
The superionic ice only lasted for mere nanoseconds before pressure waves from the surroundings broke its compression and caused it to melt. Millot and his colleagues managed to analyze its optical and thermodynamic properties.
They reported that superionic ice will melt at temperatures of 8,540 degrees Fahrenheit (4,725 degrees Celsius) and two million times the atmospheric pressure found on Earth. These conditions can be found on the surface of the Sun.
The findings of the LLNL study offered a potential insight into planets like Uranus and Neptune. Planetary researchers have theorized that water makes up 65 percent of the mass of these gas giants. Earlier studies proposed that these planets have fully fluid interiors.
However, the creation of superionic ice brought up a new possibility. Millot’s paper suggested those planets have thick mantles made up of superionic ice with a much thinner layer of fluid.
The new model would validate the results of a computer simulation performed during the 2000s. The simulation attempted to figure out the significant tilts of Uranus and Neptune’s magnetic fields.
The magnetic field of Earth is tilted 11 degrees from its axis. But Uranus’ magnetic poles have a 59-degree tilt while those of Neptune show a 47-degree tilt.
The tilts may mean the magnetic fields of the two gas giants behave differently from that of our planet. One theory suggests Uranus’ field might turn off and on like a strobe light.
The only way to confirm these theories is a new planetary mission. NASA has already raised the possibility of sending a space probe to investigate either Uranus and Neptune within the next few decades.
Millot and his colleagues at LLNL are planning to increase the compression in future experiments. By matching the atmospheric pressure in Jupiter and Saturn, they can find out if the interiors of those gas giants can support superionic ice.
You can read more articles about the solar system’s gas giants at Space.news.