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  Phone: (925) 422-9799
  April 1, 2005

Chemistry & Materials Science logoRecreating the extreme state
of water found on giant planets

By recreating extreme pressures and temperatures in the laboratory, Livermore scientists are unraveling the mysterious behavior of water in the interiors and magnetic fields of large icy planets.

Click on the arrow on the left to see an animation of liquid water at normal temperature and pressure.

The conditions in planets such as Neptune and Uranus are intense, with temperatures greater than 17,000 degrees Fahrenheit and pressures eight million times greater than that on Earth.

Under these conditions, Laboratory scientists have created a “superionic” phase of water – neither ice nor liquid – in which the oxygen atoms remain virtually stationary while the hydrogen atoms are extraordinarily mobile.

“This shows how extreme pressures and temperatures can completely transform water from a molecular system into a ‘salt’ composed of mobile protons and stationary oxygen ions,” said Alex Goncharov, a chemist and lead author of a paper that has been accepted for publication in Physical Review Letters. “This phase of water is of profound importance not only to planetary science but also to geoscience and fundamental chemistry.”

To recreate the extreme pressure required to force water into the superionic state, Goncharov’s team used a diamond anvil cell, which squeezes the water between two diamonds, creating a pressure 470,000 times greater than Earth’s atmospheric pressure. The researchers used a laser to heat the water to the intense temperature of 2,400 degrees Fahrenheit. At this pressure and temperature, the water went superionic.

Click on the arrow on the left to see an animation of water transformed to the superionic phase by extreme temperature and pressure.

In addition to laboratory experiments, the team used computer models to predict the atoms’ behavior, which showed that observed changes in the optical spectra were consistent with a superionic phase. As the temperature and pressure increase, the water molecules break apart into a non-molecular phase. The oxygen atoms are found at lattice sites, while the hydrogen atoms wander almost freely throughout the crystal. The simulations were performed using Thunder, one of Livermore’s terascale supercomputers.

If superionic water was brought to Earth, it would explode because of the extreme pressure and temperature, but inside a giant ice planet it would be hard as steel and just a bit cooler than the weakest star, Goncharov said.

The paper, titled “Dynamic Ionization of Water Under Extreme Conditions,” was written by Livermore researchers Goncharov, Nir Goldman, Laurence Fried, Jonathan Crowhurst, I-Feng Kuo, Christopher Mundy, and Joseph Zaug.

The observations and models have larger implications for the makeup of the universe. There could be more superionic water in the universe that just hasn't been observed than there is of the solid or liquid forms of water.

“I think we may have more superionic than ‘normal’ water in the icy large planets,” Goncharov said. “It is all determined by the pressure-temperature profile of the interior and the amount of material present.”

Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory that develops science and engineering technology and provides innovative solutions to our nation's most important challenges. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy's National Nuclear Security Administration.