Anat Shahar is pioneering a field that blends isotope geochemistry with high-pressure experiments to examine planetary cores and the Solar System’s formation, prior to planet formation, and how the planets formed and differentiated. Stable isotope geochemistry is the study of how physical and chemical processes can cause isotopes—atoms of an element with different numbers of neutrons-- to separate (called isotopic fractionation). Experimental petrology is a lab-based approach to increasing the pressure and temperature of materials to simulate conditions in the interior Earth or other planetary bodies.

Rocks and meteorites consist of isotopes that contain chemical fingerprints of long-gone eras. The lighter isotopes, with fewer neutrons, partially separate from heavier isotopes (fractionation). The different ratios of these isotopes can reveal the physical and chemical changes these materials have undergone.

Comparing seismic measurements and information on materials, researchers know that Earth’s outer core is not pure iron and nickel; something lighter is there. One candidate is silicon, the most abundant element in the crust. Shahar and her colleagues developed a way to test the silicon hypothesis. They developed lab techniques to define how isotopes of silicon and iron separate between metals characteristic of the core and silicate of the mantle under Earth-forming high pressures and temperatures. The results were compared with isotopes found in rocks on Earth and the most primitive meteorites called chondrites. Chondrites contain tiny grains of dust from the period when the Solar System began to coalesce. They found that the core could contain as much as 6% silicon by weight.   

Shahar received her B.S. and M. Eng. from Cornell University in geological engineering and geological sciences respectively. She received her Ph. D. in geochemistry from UCLA. Before becoming a staff scientist in 2009 she was a Carnegie postdoctoral fellow. For more see http://anatshahar.carnegiescience.edu

 

Explore Carnegie Science

GW Orionis Credit: ESO/Exeter/Kraus et al., ALMA (ESO/NAOJ/NRAO)
September 3, 2020

Washington, DC— The discovery that our galaxy is teeming with exoplanets has also revealed the vast diversity of planetary systems out there and raised questions about the processes that shaped them. New work published in Science by an international team including Carnegie’s Jaehan Bae could explain the architecture of multi-star systems in which planets are separated by wide gaps and do not orbit on the same plane as their host star’s equatorial center.

“In our Solar System, the eight planets and many other minor objects orbit in a flat plane around the Sun; but in some distant systems, planets orbit on an incline—sometimes a very steep one,”

Earth's layers courtesy of Shutterstock
August 31, 2020

Washington, DC— The composition of Earth’s mantle was more shaped by interactions with the oceanic crust than previously thought, according to work from Carnegie’s Jonathan Tucker and Peter van Keken along with colleagues from Oxford that was recently published in Geochemistry, Geophysics, Geosystems.

During its evolution, our planet separated into distinct layers—core, mantle, and crust. Each has its own composition and the dynamic processes through which these layers interact with their neighbors can teach us about Earth’s geologic history.

Plate tectonic processes allow for continuous evolution of the crust and play a key role in our planet

Quartz crystals courtesy of Shutterstock.
August 26, 2020

Washington, DC— When a meteorite hurtles through the atmosphere and crashes to Earth, how does its violent impact alter the minerals found at the landing site? What can the short-lived chemical phases created by these extreme impacts teach scientists about the minerals existing at the high-temperature and pressure conditions found deep inside the planet?

New work led by Carnegie’s Sally June Tracy examined the crystal structure of the silica mineral quartz under shock compression and is challenging longstanding assumptions about how this ubiquitous material behaves under such intense conditions. The results are published in Science Advances.

"Quartz is one

Johanna Teske
August 19, 2020

Washington, DC— In September, astronomer Johanna Teske will join Carnegie’s Earth and Planets Laboratory as a Staff Scientist. Teske has been with Carnegie since 2014, first as the inaugural Carnegie Origins Postdoctoral Fellow and currently as a NASA Hubble Fellow. 

“I’m thrilled to be able to continue my career at Carnegie and to be the first Staff Scientist hired at the newly formed EPL,” Teske said. “This institution has shaped my approach to research and I am excited to advance to the next stage of my career as one of its faculty.”   

Teske’s work aims to help scientists better understand the

No content in this section.

Established in June of 2016 with a generous gift of $50,000 from Marilyn Fogel and Christopher Swarth, the Marilyn Fogel Endowed Fund for Internships will provide support for “very young budding scientists” who wish to “spend a summer getting their feet wet in research for the very first time.”  The income from this endowed fund will enable high school students and undergraduates to conduct mentored internships at Carnegie’s Geophysical Laboratory and Department of Terrestrial Magnetism in Washington, DC starting in the summer of 2017.

Marilyn Fogel’s thirty-three year career at Carnegie’s Geophysical Laboratory (1977-2013), followed

CALL FOR PROPOSALS

Following Andrew Carnegie’s founding encouragement of liberal discovery-driven research, the Carnegie Institution for Science offers its scientists a new resource for pursuing bold ideas.

Carnegie Science Venture grants are internal awards of up to $100,000 that are intended to foster entirely new directions of research by teams of scientists that ignore departmental boundaries. Up to six adventurous investigations may be funded each year. The period of the award is two

Andrew Steele joins the Rosetta team as a co-investigator working on the COSAC instrument aboard the Philae lander (Fred Goesmann Max Planck Institute - PI). On 12 November 2014 the Philae system will be deployed to land on the comet and begin operations. Before this, several analyses of the comet environment are scheduled from an approximate orbit of 10 km from the comet. The COSAC instrument is a Gas Chromatograph Mass Spectrometer that will measure the abundance of volatile gases and organic carbon compounds in the coma and solid samples of the comet.

Carbon plays an unparalleled role in our lives: as the element of life, as the basis of most of society’s energy, as the backbone of most new materials, and as the central focus in efforts to understand Earth’s variable and uncertain climate. Yet in spite of carbon’s importance, scientists remain largely ignorant of the physical, chemical, and biological behavior of many of Earth’s carbon-bearing systems. The Deep Carbon Observatory (DCO) is a global research program to transform our understanding of carbon in Earth. At its heart, DCO is a community of scientists, from biologists to physicists, geoscientists to chemists, and many others whose work crosses these

Johanna Teske became the first new staff member to join Carnegie’s newly named Earth and Planets Laboratory (EPL) in Washington, D.C., on September 1, 2020. She has been a NASA Hubble Fellow at the Carnegie Observatories in Pasadena, CA, since 2018. From 2014 to 2017 she was the Carnegie Origins Postdoctoral Fellow—a joint position between Carnegie’s Department of Terrestrial Magnetism (now part of EPL) and the Carnegie Observatories.

Teske is interested in the diversity in exoplanet compositions and the origins of that diversity. She uses observations to estimate exoplanet interior and atmospheric compositions, and the chemical environments of their formation

Phillip Cleves’ Ph.D. research was on determining the genetic changes that drive morphological evolution. He used the emerging model organism, the stickleback fish, to map genetic changes that control skeletal evolution. Using new genetic mapping and reverse genetic tools developed during his Ph.D., Cleves identified regulatory changes in a protein called bone morphogenetic protein 6 that were responsible for an evolved increase in tooth number in stickleback. This work illustrated how molecular changes can generate morphological novelty in vertebrates.

Cleves returned to his passion for coral research in his postdoctoral work in John Pringles’ lab at Stanford

Brittany Belin joined the Department of Embryology staff in August 2020. Her Ph.D. research involved developing new tools for in vivo imaging of actin in cell nuclei. Actin is a major structural element in eukaryotic cells—cells with a nucleus and organelles —forming contractile polymers that drive muscle contraction, the migration of immune cells to  infection sites, and the movement of signals from one part of a cell to another. Using the tools developed in her Ph.D., Belin discovered a new role for actin in aiding the repair of DNA breaks in human cells caused by carcinogens, UV light, and other mutagens.

Belin changed course for her postdoctoral work, in

Evolutionary geneticist Moises Exposito-Alonso joined the Department of Plant Biology as a staff associate in September 2019. He investigates whether and how plants will evolve to keep pace with climate change by conducting large-scale ecological and genome sequencing experiments. He also develops computational methods to derive fundamental principles of evolution, such as how fast natural populations acquire new mutations and how past climates shaped continental-scale biodiversity patterns. His goal is to use these first principles and computational approaches to forecast evolutionary outcomes of populations under climate change to anticipate potential future