The exotic ice of space

The gas giants Uranus and Neptune are rich in water. It was thought that hot ice formed there, black and heavy, solid and liquid at the same time. Recently, scientists recreated this type of ice in the laboratory. The exotic ice from space is called superionic ice. They described its crystalline structure.

From our terrestrial environment, one might think that water is a simple elbow-shaped molecule. It is formed by an oxygen atom bonded to two hydrogens. They settle into a fixed position when water freezes.

Exotic ice from space was replicated in an experiment.
Exotic ice from space was replicated in an experiment.

Ice that doesn’t melt

Superionic ice is strangely different. And yet, it may be one of the most abundant forms of water in the Universe. It is assumed to fill not only the interiors of Uranus and Neptune, but also similar exoplanets. These planets have extreme pressures of 2 million times Earth’s atmosphere. Their interiors are as hot as the surface of the Sun.

In 2019, what physicists had predicted in 1988 was already confirmed. The oxygen atoms in superionic ice are enclosed in a solid cubic lattice. Meanwhile, ionized hydrogen atoms break loose, flowing through that network like electrons through metals. This raises its melting point. That is why frozen water remains solid at high temperatures.

A new study, published in Scientific Reports, was carried out by physicists at Stanford University, United States. They bombarded thin layers of water, sandwiched between two diamonds, with very powerful lasers. They raised the pressure to 200 Gigapascal (GPa), which is 2 million atmospheres. The temperatures rose to about 4,700 °С.

This type of ice resists very high temperatures.
This type of ice resists very high temperatures.

magnetic fields

The researchers discovered that the ice crystals were a new phase distinct from the superionic ice observed in 2019. The newly discovered superionic ice, Ice XIX, has a cubic structure and higher conductivity. Much more so than its 2019 predecessor, Ice XVIII.

Thanks to its structure, this new form of ice is distinguished by greater conductivity. It generates magnetic fields as unequal as those emanating from Uranus and Neptune. 30 years ago the Voyager II probe flew near the two ice giants, measuring their unusual magnetic fields. And at last we have a clue to the causes, and they are related to the exotic ice of space, the American physicists concluded.

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