Research Highlight: Squeezing Out the Story of Planets

A grant received this year through the National Science Foundation (NSF) shows that Scripps Institution of Oceanography at the University of California San Diego is emerging as a global center for the study of high-pressure geology.

Scripps’ entrée into this area of research largely began with the 2014 appointment of Anne Pommier as an assistant professor of geophysics. She founded the Planetary and Experimental Petrology Laboratory (PEPL) at Scripps, where she studies the interior of planets, specifically terrestrial bodies like Earth, the Moon, Mars, and Mercury, which are thought to have metallic cores and silicate mantles.

Pommier has recently been awarded a grant from COMPRES, the Consortium for Materials Properties Research in Earth Sciences, through a new NSF Cooperative Agreement. COMPRES is a community-based consortium that enables earth and planetary science researchers in the United States and abroad to conduct high-pressure science on world-class equipment at leading-edge facilities. Besides facilitating the development of new technologies for high-pressure research, COMPRES also advocates for science and educational programs.

The grant affords Scripps important visibility within the high-pressure scientific community. The project it funds focuses on the development of in situ and real-time electrical measurements under pressure in order to investigate the properties associated with mass or heat transport in planetary mantles and cores.

The prevailing view among scientists is that as a terrestrial body cools down, metal sinks to form the planetary core. Although all terrestrial bodies are thought to have experienced these processes, they are extremely different in terms of size, chemistry, and magnetic activity.

“One exciting topic in earth and planetary sciences is to understand how these common processes operate and what made terrestrial planets so different from each other at some point in their history,” Pommier said.
 

Current research projects conducted in PEPL by Pommier’s group as well as with national and international collaborators focus on subduction processes, the core-mantle boundary of small planets, and the cooling of metallic cores.

To study the structure and dynamics of planets, Pommier and her research group mimic the pressure and temperature conditions of planetary interiors using two PEPL presses, one of which allows applying up to 30 units of pressure known as gigapascals to the sample. This corresponds to about 900 kilometers (560 miles) depth in the Earth, covers the entire depth of Mercury and almost the entire depth of Mars. The higher the temperature and the pressure achieved in the lab, the greater the depth researchers reach inside the planet, Pommier said.

After getting a civil engineering degree, a master’s in geosciences, and a PhD in experimental petrology in France, Pommier moved to the United States as a postdoctoral researcher before starting her current position at Scripps.

“There are very few people in the world who do these types of experiments, and among them, very few are female faculty,” Pommier said.

The grant recognizes and supports her innovations in finding new ways to gather experimental data.

“It is an exciting time to investigate planetary interiors using high-pressure science, as new tools and techniques allow probing processes that were not accessible before,” she said.

–      Mallory Pickett

Related Image Gallery: Squeezing Out the Story of Planets