August 2020 - Letter from the Directors

August 2020 Letter from the Directors - Crator
A photograph of a meteorite strike site in Coconino County, Arizona. New work from Carnegie’s Sally June Tracy and collaborators Stefan Turneaure of Washington State University and Thomas Duffy of Princeton University reveals an unexpected new form of silica created in the type of extreme conditions caused by an impact. Image is courtesy of Shutterstock.
Friday, August 28, 2020 

Normally August is a quiet time on campus as staff are out on summer holidays or off doing field work in remote corners of the world.  This year is different in so many ways.  

Two New Staff Scientists

On the very good news front, we are pleased to report the hire of two new scientific staff members focused on different aspects of exoplanet science.  These two are the first staff scientists hired following the formation of the Earth and Planets Laboratory (EPL).    

Johanna Teske recently arrived in Washington, and after having now passed the required COVID screening protocols, will be starting on campus in September.  Teske uses various observational approaches to detect and characterize the mass and composition of exoplanets.  

Joining us next fall, after spending a year as Sagan Fellow at UC Santa Cruz, is Peter Gao.  Gao’s work focuses on the physics and chemistry of the atmospheres of exoplanets and the outer planets and moons in our Solar System. 

The combination of expertise from these two will contribute in important ways to the quest at EPL to understand how planets form and the processes that determine their size, composition, and potential to harbor life. We very much look forward to the energy and exciting new ideas they will bring to EPL.

Meteorite This Way! 

A back-scattered electron image showing one of the products of Chabot’s lab at APL mimicry of the core crystallization process. Liquid metal is on the right and solid metal is on the left. Image is courtesy of Nancy Chabot and Peng Ni.

A good portion of the science news in this month’s newsletter highlights the importance of meteorites as a tool to study topics ranging from the deepest interior of planets to how life may have started on Earth.  

 We are particularly pleased that two of our former postdoctoral fellows working in this field, Nan Liu and Maria Schönbächler, were selected to receive major awards from the Meteoritical Society next year.  Meteoritics and cosmochemistry provide the connecting sinews between the astronomical and the petrological components of our investigation of planet characteristics.  

A good example is the connection of the work of postdoctoral Fellow Peng Ni and staff scientist Anat Shahar, who used the iron isotopic composition of iron meteorites to understand how the cores of small asteroids formed 4.56 billion years ago.  

An independent, but topically related, study done by staff scientists Yingwei Fei and Ron Cohen used high-pressure experiments and first-principles molecular dynamics calculations to determine the heat conductivity of iron metal at the temperatures and pressures found in Earth’s core.  Both studies address what is arguably the most important chemical differentiation event in the history of a planet, core formation and evolution, but do so using very different approaches.  

Impacts Great and Small

This is an image of a polished thin section of meteorite Asuka 12236, made with a scanning electron microscope. Credits: Carnegie Institution for Science/Conel M. O'D. Alexander

Moving away from the Earth’s core, two more studies explore the consequences of the gentle or violent collision of meteors with Earth’s surface.  

On the gentle side, work involving staff scientists Larry Nittler and Conel Alexander with colleagues from Goddard Space Flight Center shows that a meteorite found in Antarctica may still preserve delicate features of rock-water interaction on the asteroidal parent body of this meteorite.  The sample was so unaltered during its delivery to Earth that mineralogical and chemical features of early low-temperature chemical processes on its parent asteroid are preserved.  These features include the apparent synthesis of an abundance of amino acids, including a possible explanation to why life on Earth prefers only the left-handed versions of amino acids.  

Shutterstock Quartz Crystals
A photograph of quartz, one of the most abundant minerals in the Earth’s crust. It is made from one atom of silicon and two atoms of oxygen in a tetrahedral lattice structure. A new paper in Science Advances shows a new form of silica created when quartz experiences an impact event. Understanding this chemical transformation could help scientists understand planetary formation and evolution. Image is courtesy of Shutterstock.

At the other extreme, using a high-velocity cannon, staff scientist Sally Tracy examined the consequences of the very violent impact of a large meteorite into Earth’s surface.  Tracy’s work shows that the very short duration, but exceedingly high pressures and temperatures of such an impact turns quartz —silicon dioxide, one of the most abundant minerals in Earth’s continents—into a mixture of both glass and a mineralogical form of silicon dioxide that was believed to exist primarily only at great depth in Earth’s interior.

Bringing Back Events...Virtually! 

Though the coronavirus still keeps us from the social gatherings that we all now appreciate more than ever, September will see the reappearance of some of our normal events and seminars, now in virtual formats. 

At the more technical end, our twice-weekly seminar program will now include speakers from around the world (virtually), no longer constrained by the need to travel.  

We are also pleased to announce that our Neighborhood Lecture series will return on September 24 when Rick will describe the results of his work on Earth’s oldest rocks. The data help answer questions about how the Moon formed, why Earth is the only planet we know of with continents, and when Earth’s surface may have reached a state supportive of the development of life. 

Needless to say, you’re invited! We can’t wait to see you there.

Richard Carlson, Director, Carnegie Earth and Planets Laboratory
Carnegie Institution for Science

Michael Walter, Deputy Director, Carnegie Earth and Planets Laboratory
Carnegie Institution for Science 

August 2020 Newsletter