LPI Welcomes New Postdoctoral Fellow Brendan Anzures

April 28, 2022

Recently, LPI welcomed a new postdoctoral fellow, Dr. Brendan Anzures. Dr. Anzures is a planetary petrologist and geochemist with a spectroscopist twist interested in the chemical, thermal, and redox evolution of airless rocky bodies in the early solar system (Mercury, meteorites, and asteroids). He will be in residence at NASA JSC working with Drs. Cyrena Goodrich (LPI) and Francis McCubbin (JSC).

Read LPI’s interview with Dr. Anzures below to learn more.

Brendan simulating planetary core formation

Brendan simulating planetary core formation using high-pressure, high-temperature X-ray microtomography at Argonne National Lab during his sophomore year of college (3D imaging of a synthetic rock during melting and deformation).

LPI: How did you become interested in planetary science?
BA: I have always been much more impressed by the natural world than anything envisioned by the human mind. The beauty and complexity of nature seem to stand out, a deep and wondrous gallery not limited by our thoughts or imaginations. Rocks and minerals especially interest me because, for the most part, they last. All living organisms are magnificent in their time, but they fade quickly. It seems almost otherworldly that many geologic landscapes and individual minerals formed tens of thousands to millions of years ago when we live maybe a hundred years and the oldest trees, a few thousand. Geologic attractions such as the Grand Canyon, the hot springs at Yellowstone, and the volcanoes of Hawaii — three places I had the privilege of seeing when I was young — inspire awe among everyone who visits. But as much as I was fascinated by rocks and minerals and their longevity growing up, I could never really grasp how and why they form the way they do.

LPI: When did you know that you wanted to pursue this as a career?
BA: I got the chance to learn answers to some of those questions when I became an undergraduate research assistant early on at Rensselaer Polytechnic Institute, working with experimental geochemist and mineral physicist Dr. Heather Watson. Together, we investigated the formation of metal cores in planetesimals and objects in our solar system around 100 kilometers in diameter. I was (and still am) fascinated that we can study fundamental planetary processes from samples smaller than a thumbtack, whether they are synthetic rocks I have produced in the lab or meteorites from space. This project expanded my curiosity from not only individual rocks and minerals, but to entire planets and planetary systems. And I have carried that momentum through graduate school to become a planetary scientist!

Brendan and undergrad research advisor Dr. Heather Watson

Brendan with his undergrad research advisor Dr. Heather Watson at LPSC after he graduated.

LPI: Did you have a mentor or another person in your life who was influential to your decision or career?
BA: My undergraduate research advisor Dr. Heather Watson gave me my first taste of planetary science research. She is a great mentor who always asks how I am doing and how my family is before we talk science. After all, scientists are humans first. The two trips we made to Argonne National Lab to do beamline work stand out as highlights of my undergraduate experience. Even though it was rigorous work ― 72 hours of beam time with about 10 hours of sleep the first time we went ― it helped me better understand and appreciate the sometimes-heavy demands of research. Our reward was Chicago deep-dish pizza from Lou Malnati’s!

LPI: What is the focus of your research?
BA: I am a planetary geochemist with a spectroscopist twist interested in the chemical, thermal, and redox evolution of airless rocky bodies in the early solar system (Mercury, meteorites, and asteroids). I study meteorites and synthetic rocks created through high-pressure and high-temperature experiments (like an alchemist!) using various laboratory spectroscopy techniques, with a special focus on the behavior of volatiles (S, C, F, Cl, and H2O).

During my time at LPI and the Astromaterials Research and Exploration Science Division (ARES) at NASA Johnson Space Center, I am working on experimentally determining the partitioning behavior of major, minor, and trace elements between silicate melt, sulfide melt, and metal under highly reduced, S-rich conditions relevant to Mercury, enstatite chondrites, and aubrites, a parameter space where little data currently exist. In these same samples, I will measure the S, Cl, and Cr speciation in the silicate melts to better understand how these heterovalent elements compete with O to bond with common cations like Fe, Ca, and Mg impacting metal and sulfide complexing and transport during differentiation. Another project in collaboration with researchers at UC Santa Cruz is investigating enstatite chondrite outgassing and development of primordial atmospheres with implications for enstatite chondrite parent bodies, early Earth, and exoplanets.

Graph of Sulfur speciation in silicate melt as a function of oxygen fugacity

Sulfur speciation in silicate melt as a function of oxygen fugacity.

LPI: What is the most unexpected or exciting result you’ve encountered in your research?
BA: Why is it that the Moon and Mercury are roughly the same size, yet are completely different in almost all geochemical and geophysical aspects? Why is S solubility so high at low oxygen fugacity, as observed on Mercury’s surface and in enstatite chondrites and aubrites?

The NASA MESSENGER mission revealed that lavas on Mercury are enriched in sulfur (1.5-4 wt.%) compared with other terrestrial planets (<0.1 wt.%), a result of high S solubility at its very low oxygen fugacity. To further understand S solubility and speciation in reduced magmas, I used S K-edge X-ray absorption near edge structure (XANES) spectroscopy to measure S-speciation in 60 high pressure and temperature experiments. I discovered that as ƒO2 decreases from IW-2 to IW-7, the dominant sulfur species in silicate melts change from FeS to CaS to MgS. The changes in S speciation have substantial impacts on the chemical and physical properties of the melts, which have led to Mercury’s distinct evolution. Our results on S speciation at low ƒO2 are also applicable to the petrologic evolution of enstatite chondrite parent bodies, perhaps early Earth, and exoplanets around C-rich stars that may have formed under similarly reducing conditions. The results of this work are published in American Mineralogist and Geochimica et Cosmochimica Acta, with a third paper in preparation!

LPI: What do you most look forward to as it relates to planetary science over the next 10 years?
BA: Given my interest in Mercury, I am super excited for BepiColombo, which is a European Space Agency (ESA)/Japanese Aerospace Exploration Agency (JAXA) mission comprised of two orbital spacecraft to explore Mercury. It is the third mission to Mercury after NASA’s Mariner 10 (1974–1975) and MESSENGER (2011–2015). It launched in 2018, will begin orbiting Mercury in 2025, and will provide exciting new constraints on the chemistry, mineralogy, and petrologic evolution of the planet, especially the lightly explored southern hemisphere!

It is also the golden age of small body exploration, which will help contextualize and expand our research of meteorites and the early solar system! Recent sample-return missions to hydrous asteroids, JAXA’s Hayabusa2 (already returned) and NASA’s OSIRIS-REx (returning to Earth in 2023), have revealed more and more asteroids are rubble-piles with surfaces dominated by boulders rather than regolith. This implies that catastrophic fragmentation due to collisions was more common in the early solar system than previously thought! And in the coming decade, NASA has missions Lucy to primitive carbon- and water-rich asteroids called Trojans associated with Jupiter (launched in 2021 for a nominal 12-year mission); Psyche to a metal-rich asteroid that may be an exposed planetary core (launching later this year to arrive in 2026); and a planetary defense focused mission DART (Double Asteroid Redirection Test), scheduled to impact later this year.

Brendan running

Brendan running a 1:30:33 half marathon in Pearland, Texas.

LPI: What would be your dream research trip?
BA: I am very much a lab rat, so the coolest place I’ve been (seven times now) for research has to be the Advanced Photon Source (APS) at Argonne National Lab, which is a synchrotron facility outside of Chicago. A synchrotron facility is a type of particle accelerator that sends charged particles such as electrons around at relativistic speeds to produce high-intensity x-rays for a bunch of scientific applications. Plus, APS has this spiderman tricycle to move around quickly (and help stay awake for long hours) in the ~1100m circumference ring (large enough to fit a basketball park in its center!). Another synchrotron facility that’s probably better known is the Large Hadron Collider, which would be fascinating to visit!

LPI: Do you have a favorite hobby or interest outside of work?
BA: Outside of work I enjoy trying different food, traveling (visited over half the states and 11 countries so far), reading science fiction, fantasy, and theology (highly recommend N.K. Jemison’s Broken Earth trilogy for geologists!), video games (role-playing and multiplayer FPS and TPS games), and playing most sports. I play pickup basketball, soccer, and tennis, and have completed a marathon, triathlon, and last month ran a 1:30 half marathon as my outside-of-work goal for 2022!

For more information, visit Dr. Brendan Anzures.

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