Nav: Home

Better model of water under extreme conditions could aid understanding of Earth's mantle

June 20, 2018

Deep inside the Earth exist pockets of water, but the liquid there isn't like the water on the surface.

When exposed to unimaginably high temperatures and pressures, water exhibits all sorts of weird phases and properties, from remaining a liquid at temperatures 10 times higher than the boiling point to existing as a liquid and a solid at the same time.

This strange world is still not fully understood, but a team of University of Chicago scientists ran quantum simulations to develop a new model of the behavior of water at extremely high temperatures and pressures. The computational measurements, published June 18 in the Proceedings of the National Academy of Sciences, should help scientists understand water's role in the makeup of the mantle and potentially in other planets.

"Subtle physics at the molecular level can impact properties of matter deep inside planets," said Viktor Rozsa, a UChicago graduate student and first author on the paper. "How water reacts and transports charge on a molecular scale affects our understanding of phenomena ranging from the movement of magma, water and other fluids to the magnetic field of the entire planet."

Under the conditions considered in the study--more than 40 times hotter than our everyday conditions and 100,000 times greater than atmospheric pressure--water is regularly ripping apart and re-forming its own chemical bonds. The result is that it can interact very differently with other minerals than it does on the surface of the earth.

Scientists have been trying to pin down exactly how these atoms interact for decades: It's extremely difficult to test experimentally, as water can react with the instrument itself. "It's surprising how little we know about water below the crust," said lead author Giulia Galli, the Liew Family Professor of Molecular Engineering and professor of chemistry at UChicago and a senior scientist at Argonne National Laboratory.

But water in these conditions exists throughout the mantle--it's possible there may be more water distributed inside the Earth than there is in the oceans--and scientists would like to know exactly how it behaves in order to understand its role in the Earth and how it moves through the mantle.

Galli's group built a model by performing quantum mechanical simulations of a small set of water molecules at extremely high pressures and temperatures--in the range of what you need to synthesize a diamond.

Their model, built with the aid of simulations performed at the Research Computing Center at UChicago, provides an explanation for some of water's more mysterious properties at such pressures, such as the connection between bizarrely high conductivity and how its molecules disassociate and re-associate.

It also predicts and analyzes a controversial set of measurements called the vibrational spectroscopic signatures of water, or fingerprints of molecular movement that lay out how molecules are interacting and moving.

In addition to furthering understanding of our own planet, Galli said, "the ability to do the kind of simulations performed in our paper could have important consequences on modeling exoplanets." Many scientists, including those at UChicago, are narrowing the conditions for distant planets that might have the conditions to create life, and much of this search revolves around water.

Galli is a member of the research team in the Institute for Molecular Engineering's water theme, led by James Skinner, the Crown Family Professor of Molecular Engineering. The team seeks to understand the physical, chemical and biological manifestations of water, and to develop applications from innovative purification filters, to new materials for desalination and lithium ion harvesting, to new catalysts for water chemistry and disinfection.

While water is everywhere and intensively important to us, Galli said, it is notoriously difficult to simulate and study: "This is one step in the long journey to understanding."
-end-
Other authors on the study were UChicago postdoctoral researcher Federico Giberti and Ding Pan, a former postdoctoral associate and now a professor at the Hong Kong University of Science and Technology.

University of Chicago

Related Planets Articles:

How planets may form after dust sticks together
Scientists may have figured out how dust particles can stick together to form planets, according to a Rutgers co-authored study that may also help to improve industrial processes.
Planets around a black hole?
Theoreticians in two different fields defied the common knowledge that planets orbit stars like the Sun.
The rare molecule weighing in on the birth of planets
Astronomers using one of the most advanced radio telescopes have discovered a rare molecule in the dust and gas disc around a young star -- and it may provide an answer to one of the conundrums facing astronomers.
How many Earth-like planets are around sun-like stars?
A new study provides the most accurate estimate of the frequency that planets that are similar to Earth in size and in distance from their host star occur around stars similar to our Sun.
Dead planets can 'broadcast' for up to a billion years
Astronomers are planning to hunt for cores of exoplanets around white dwarf stars by 'tuning in' to the radio waves that they emit.
The sun follows the rhythm of the planets
One of the big questions in solar physics is why the sun's activity follows a regular cycle of 11 years.
Five planets revealed after 20 years of observation
To confirm the presence of a planet, it is necessary to wait until it has made one or more revolutions around its star.
Icy giant planets in the laboratory
Giant planets like Neptune may contain much less free hydrogen than previously assumed.
New NASA mission could find more than 1,000 planets
A NASA telescope that will give humans the largest, deepest, clearest picture of the universe since the Hubble Space Telescope could find as many as 1,400 new planets outside Earth's solar system, new research suggests.
Giant planets around young star raise questions about how planets form
Researchers have identified a young star with four Jupiter and Saturn-sized planets in orbit around it, the first time that so many massive planets have been detected in such a young system.
More Planets News and Planets Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Making Amends
What makes a true apology? What does it mean to make amends for past mistakes? This hour, TED speakers explore how repairing the wrongs of the past is the first step toward healing for the future. Guests include historian and preservationist Brent Leggs, law professor Martha Minow, librarian Dawn Wacek, and playwright V (formerly Eve Ensler).
Now Playing: Science for the People

#566 Is Your Gut Leaking?
This week we're busting the human gut wide open with Dr. Alessio Fasano from the Center for Celiac Research and Treatment at Massachusetts General Hospital. Join host Anika Hazra for our discussion separating fact from fiction on the controversial topic of leaky gut syndrome. We cover everything from what causes a leaky gut to interpreting the results of a gut microbiome test! Related links: Center for Celiac Research and Treatment website and their YouTube channel
Now Playing: Radiolab

The Flag and the Fury
How do you actually make change in the world? For 126 years, Mississippi has had the Confederate battle flag on their state flag, and they were the last state in the nation where that emblem remained "officially" flying.  A few days ago, that flag came down. A few days before that, it coming down would have seemed impossible. We dive into the story behind this de-flagging: a journey involving a clash of histories, designs, families, and even cheerleading. This show is a collaboration with OSM Audio. Kiese Laymon's memoir Heavy is here. And the Hospitality Flag webpage is here.