September 2021 Letter from the Directors

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Wednesday, September 01, 2021 

Welcome to new scientists on campus!

Although the Earth and Planets Laboratory (EPL) does not follow a traditional academic school year, some aspects of campus activity are influenced by “the summer break”.  We are coming up on “back to school” when family vacations are concluding and the new “class” of postdocs arrive to begin their work at EPL.  Because of recent successes with federal funding and the continuing support of the Carnegie Institution, this year’s incoming postdoc class is unusually outstanding in number, but with the usual high levels of expertise and experience typical of those who choose to pursue postdoctoral work at Carnegie.

EPL attracts postdoc candidates from top universities around the world.  Science has always been an international activity and is becoming even more so.  Unfortunately, the labyrinth that the U.S. immigration system has become, coupled with the travel restrictions imposed for covid mitigation are weakening our ability to bring in the best early-career scientists from around the world, resulting in some cases in delays of over a year in the planned arrival times of some of our new postdocs. We are working hard to overcome these barriers and get everyone to campus.

In addition to the new class of postdocs, EPL welcomes two new staff scientists: Peter Gao and Anne Pommier.  Moving to a new workplace and setting up—or reestablishing—one’s research program is a major task that can take time and a lot of work.  A good example is the high-pressure lab being set up by Staff Scientist Pommier

Setting up the new high-pressure lab

Pommier arrived at EPL in early July followed within a week by the arrival of the equipment she had shipped from her previous lab at the Scripps Institution of Oceanography to be installed in her new lab at EPL. Through the hard work of Gary Bors and his team of building engineers, Pommier’s lab space was renovated, and the equipment installed.  One of the first tests Pommier completed on the multi-anvil high-pressure device was to see if the press-rams are correctly aligned so that they evenly transmit the applied pressure to the sample placed into an octahedral-shaped void made by grinding triangular facets on eight WC cubes.

Testing alignment is done by inserting an octahedral block of copper where the sample would normally go.  Copper is an easily deformed metal and well shows whether all eight WC cubes are pressing on it equally from all sides - they did, even in this first test.  The result also provides a good example of what 172 tons of pressure on the rams, corresponding to a pressure of 4.2 GPa (~610 thousand psi), does to the sample.

This successful first test reflects not only the considerable expertise of Pommier with this kind of apparatus but also the strong and skilled support provided by the EPL engineering staff that allowed a lab to be renovated and become functional in just over a month

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From the arrival of Pommier’s multi-anvil high-pressure press at the EPL loading dock, to the renovation of the laboratory and installation of the press, to the first successful test of its ability to create gigapascals of pressure took just shy of two months.  Photos by Anne Pommier.

From asteroids to exoplanets

An artist’s conception of the newly discovered asteroid 2021 PH27, which has the shortest known orbital period for an asteroid and second shortest for any object in our Solar System after Mercury. Illustration by Katherine Cain courtesy of the Carnegie Institution for Science.

On the new discovery front, Staff Scientist Scott Sheppard reported the sighting of yet another object wandering around in the Solar System, this time inside the orbit of Earth unlike his many past discoveries in the outer Solar System. The new object is an asteroid about one kilometer in diameter that follows an elliptical orbit that crosses the orbits of Mercury and Venus. 

With an orbital period of 113 days, this asteroid has the shortest known orbital period of any asteroid—second only to Mercury.  This kind of object mostly likely reflects the gravitational tug-of-war between objects in the main asteroid belt with the planetary behemoths Jupiter and Saturn that occasionally throws objects from the main asteroid belt into the inner Solar System ultimately to collide with one of the terrestrial planets or the Sun.  

Most of the meteorites that have arrived at Earth likely reflect similar stories of objects that were gravitationally ejected from the asteroid belt.  Not wanting to depend on this random mechanism for sampling asteroids, a couple of recent space missions were designed to go out to the asteroid belt, scoop up some sample from a target asteroid and bring it back to Earth. 

One of these, the Hayabusa2 mission from Japan, returned samples of the Ryugu asteroid, a very small amount of which is currently inside the ion probe at EPL being analyzed by Staff Scientist Larry Nittler and postdoctoral fellow Jens Barosch for the isotopic composition of its organic constituents.  Ryugu appears to be similar to a particularly primitive type of carbonaceous chondrite and thus may provide a sample of the least thermally-metamorphosed material preserved from the early history of the Solar System.  The analyses being done by Nittler and Barosch will provide information on how this primitive organic material formed and whether it might be the material from which life eventually arose on Earth.

The tiny speck in the middle of this slide is a sample of Ryugu. Photo by Katherine Cain, Carnegie Institution for Science.

Outside of our Solar System, Staff Scientist Johanna Teske reported radial velocity data for 22 exoplanets detected by the TESS satellite using transit observations.  The dips in starlight that mark the passing of a planet between its star and Earth provide the size of the exoplanet, while radial velocity, tracking the gravitational pull of the planet on its star, provides the mass of the planet.  The combination of the two can be used to calculate the planet’s density, the key parameter reflecting the composition of the planet.

This work ultimately will lead to a better understanding of the architecture of other planetary systems, the mechanisms that can create different distributions of planets orbiting a central star, and whether our own Solar System is as unusual as it now seems to be.  

Celebrating Awards Across EPL

On the geophysics side of things, Carnegie has named EPL staff scientists Diana Roman and Lara Wagner (picture above) as the inaugural Harry Oscar Wood Chairs of Seismology. The designation recognizes their breakthrough research revealing our planet’s dynamic inner workings—both past, and present—as well as their work to guide disaster response preparation.

Roman's research efforts focus on the mechanics of how magma moves through the Earth’s crust, and on the structure, evolution, and dynamics of volcanic systems. Wagner uses seismic waves generated by earthquakes to probe the structures of our planet’s interior and understand how the continents were shaped.

Together, Roman and Wagner developed the Carnegie Quick Deploy Box, which packs all the necessary equipment for field seismic stations into a weatherproof container that is compact and portable enough to be transported anywhere in the world as commercial airline luggage.  This instrumentation breakthrough has allowed experts to rapidly respond to earthquakes and volcanic eruptions and in the future may enable more accurate imaging of the Earth’s interior.

Two scientists also received Carnegie Venture Grants, which are internal awards of up to $150,000 that are intended to foster entirely new directions of research by teams of scientists that ignore departmental boundaries. Up to three adventurous investigations may be funded each year, and this year scientists at EPL are involved with two of the winning projects.

Astrobiologist Andrew Steele along with colleagues Heather Meyer and Dave Ehrhardt from the Department of Plant Biology won $139,975 for the proposal, “Prion-like proteins as carriers and facilitators of molecular memory in higher plants.” Additionally, Peter Gao along with colleague Anthony Piro from Carnegie Observatories won $104,000 for the project, “Detecting the First Rocky Exomoons Outside the Solar System.” 

You’re invited to the fall 2021 Neighborhood Lecture Series

We are pleased to announce the program for the Neighborhood Lecture Series for this fall. Unfortunately, the coronavirus will keep us from resuming the on-campus presentations, so they will remain in virtual mode for the rest of the year.

This will not stop us, however, from exploring novel ways to convey the techniques we use to explore the types of science questions highlighted in past newsletters.  On September 28, Staff Scientist Tim Strobel will be speaking about “How to change the freezing point of water and other curiosities from between the anvils” where “anvils” means the tips to two diamonds pressed together to reach extremely high pressures.  Strobel will be doing a live (virtual) demonstration of how the application of pressure can cause water to freeze even at room temperature.  Human experience with materials is highly biased by their behavior under the pressure and temperature conditions found at Earth’s surface.  By changing those conditions, however, Strobel will show how new materials, some with amazing properties, can be created.

On October 26, Staff Scientist Anat Shahar will present a discussion of “What makes a planet habitable?”  She will describe an ambitious new project supported by the Sloan Foundation that will examine the feedback between the interior and exterior of a planet and what aspects of that connection are essential to allow a planet to develop and sustain life.

You can find more information about these topics and register for the lectures on our website. We hope to see you there.

Thank you,

Richard Carlson and Michael Walter
Director and Deputy Director