The Earth and Planets Laboratory hosts free weekly scientific seminars most Mondays and Thursdays. The popular seminar series covers the broad range of topics studied on our campus and are presented by both guest speakers and Carnegie scientists.
Note: These seminars are designed for a scientific audience and have limited space, so we are not advertising the Zoom links publically. However, you're still welcome to join! Just email Alycia Alexander (adalexander@carnegiescience.
- Monday, May 2, 2022, at 11:00 a.m. (virtual seminar)
Angela Marusiak, JPL
Title: Detecting Seismicity on Icy Ocean Worlds: Lessons from fieldwork and modelingAbstract: Icy ocean worlds such as Enceladus and Europa are high priority targets for NASA and planetary science. These bodies are likely seismically active due to tidal forces. Future missions, such as the Enceladus Orbilander, may carry seismic payloads with the goal of constraining seismic activity within the ice shells, and in the deeper silicate interiors. Here, Marusiak discusses how we can use modeling and fieldwork to help prepare for these potential missions by providing reasonable expectations, and potential methods and approaches for detecting seismic activity.Host: Lara Wagner
- Monday, May 9, 2022, at 11:00 a.m. (virtual seminar)
Chris Pickard, University of Cambridge
Title: Mapping the complex chemistry of dense matter
Abstract: First principles methods for the prediction of structures and chemistry at high pressures have delivered a powerful tool for the computational exploration of dense matter. While early studies focused on the exotic properties of relatively simple systems, typically the elements and binary compounds, much of the matter in the Universe is likely to be found in more complex mixtures. At the same time, the promise of discovering materials with extreme properties relies on the ability of screen a wide variety of compounds. I will reflect on why ab initio random structure searching (AIRSS) is particularly suited to these challenges, and the importance of visualising the vast datasets we are now generating.
 Conway, Lewis J., Chris J. Pickard, and Andreas Hermann. "Rules of formation of H-C-N-O compounds at high pressure and the fates of planetary ices." Proceedings of the National Academy of Sciences 118, no. 19 (2021).
 Shipley, Alice M., Michael J. Hutcheon, Richard J. Needs, and Chris J. Pickard. "High- throughput discovery of high-temperature conventional superconductors." Phys. Rev. B 104, 054501 (2021).
 Shires, Ben W.B., and Chris J. Pickard. "Visualising energy landscapes through manifold learning", Phys. Rev. X 11, 041026 (2021)
Host: Tim Strobel
- Thursday, May 12, 2022, at 11:00 a.m. (hybrid seminar)
Tolulope Olugboji, University of Rochester
Title: Seismic Imaging of Plates in a Water WorldAbstract: Seismic imaging of the oceanic lithosphere structure provides fundamental constraints on plate formation and evolution, and is necessary for understanding the role that temperature, hydration, or melts plays in controlling the strength and buoyancy of 70% of Earth’s tectonic plates. While it is easy to decipher vibrations on land and use the data to build maps of the structure of continental plates, on the seafloor, it is harder to detect and isolate vibrations generated from ambient noise or earthquakes that propagate within or across the oceanic plate. This is because these signals are often buried within the loud singing of sediments or drowned in the drone of water waves driven by tides. In this talk, I describe my group’s progress in developing techniques for silencing the singing of sediments and how they assist in the rapid separation of the noisy, yet predictable ringing from ocean plate conversions. Improved extraction of seismic waves and their interpretation with probabilistic imaging will produce high resolution images of the oceanic plate underneath submarine seismic arrays. Sharper images of ocean plate structure will advance our understanding of plate tectonic theory.Host: Lara Wagner
- Monday, May 16, 2022, at 11:00 a.m. (virtual seminar)
Jessica Barnes, University of Arizona
Title: Next-generation lunar sample science
Abstract: NASA had the foresight to lock away some material collected during the Apollo missions for future generations. NASA curation stored this material under special storage conditions, and it was unavailable for study by the science community. The premise was to save that material for a time when future generations would have access to analytical techniques beyond those available during the Apollo era. That time is now!
In preparation for future lunar missions anticipated in the 2020s it is important that we maximize the science derived from samples returned by the Apollo Program. Under NASA’s Apollo Next Generation Sample Analysis (ANGSA) program a selection of those specially stored samples is now available for study. Among those samples is Apollo 17 sample 71036. This lunar volcanic rock was stored frozen since its return in 1972. The release of sample 71036 presents a unique opportunity to study volatiles in a basalt that has been frozen and specially preserved since its arrival on Earth and to compare the results with basalts of similar bulk chemistries that have been stored at room temperature. This exceptional suite of basalts offers a chance to unravel the history of volatile loss on the Moon, from the onset of mineral crystallization through vesicle formation, sampling, and subsequent curation.
We are conducting a detailed study of the 3D mineralogy and textures; the 2D major, minor, and volatile element chemistry of phases in the Apollo 17 basalts; and we are determining the exposure and eruption ages of the basalts. The work plan involves a consortium of institutions and coordination of a myriad of analytical techniques. Our goal is not only to better understand the origin and evolution of the Moon but to also address some outstanding questions regarding the long-term storage and handling of extraterrestrial materials. In the EPL talk I’ll present some of our most recent findings.
Hosts: Dionysis Foustoukos and Peng Ni
- Monday, May 23, 2022, at 11:00 a.m. (virtual seminar)
Michael Wong, Earth and Planets Laboratory
Title: Atmospheric Chemical Networks & Potential Agnostic Biosignatures
Abstract: The network topologies of atmospheric chemical networks have the potential to serve as an agnostic biosignature, because such a description relies less on specific molecules but rather on the nature of the relationships among molecules. We map the chemical reaction networks of Solar System atmospheres using reaction lists from the Caltech/JPL photochemical model KINETICS, a versatile and extensively validated code for simulating planetary atmospheric chemistry. Specifically, we analyze chemical reaction networks for: Earth (modern and paleo), Mars (modern and paleo), Venus, Jupiter, Titan, and Pluto. We visualize planetary atmospheres as force-directed unipartite networks, where nodes are chemical species linked by shared reactions. This visualization allows us to qualitatively gauge network characteristics, such as symmetry, “hub” vs. “spoke” nodes, deceptively important nodes (low degree but high centrality), and node distance. We also quantify networks using global network metrics including but not limited to: clustering, transitivity, degree distribution, various centrality distributions, and modularity calculated via community detection algorithms. Modern Earth can be distinguished via different metrics; our atmosphere stands out against various planetary networks and is more similar to certain biological networks. In future work, we will use weighted and directed network representations, which will incorporate far more information about chemical networks, including abundances, fluxes, and reaction rates. If network metrics can robustly group stages of biological evolution across worlds with different geochemical contexts, this may help uncover a possible universal connection between life and planetary complexity and shed light on a theory of life at the planetary scale.
Host: Robert Hazen
- Monday, May 23, 2022, at 11:30 a.m. (virtual seminar)
Claire Zurkowski, Earth and Planets Laboratory
Title: Synthesis of an Eight-Coordinated Fe3O4 High-Pressure Phase: Implications for the Mantle Structure of Super-Earths
Abstract: The high pressure-temperature behavior of Fe3O4 captures broad Earth and planetary interest owing to its mixed-valence properties, indication of mantle oxidation, and analogous behavior to high-pressure Mg-silicates. In this talk, I will discuss our recent investigations into the crystal chemistry of Fe3O4 at pressures between 45 – 115 GPa and temperatures up to 3000 K using powder and single-crystal X-ray diffraction in the laser-heated diamond anvil cell. At pressures and temperatures greater than 60 GPa and 2000 K, we identified a transition in Fe3O4 from Fe in 6-fold coordination to Fe in 8-fold coordination that is analogous to the predicted transition in Mg2SiO4 above 500 GPa in super-Earth mantles. The pressure-volume behavior observed in this 8-fold coordinated Fe3O4 suggests the analogous coordination change across the post-post spinel transition in Mg2SiO4 will not significantly affect the density profiles of super-Earths in comparison to the 4- to 6-fold transition at shallower depths. This coordination change may still have profound consequences on the rheological and thermodynamic properties of super-Earth mantles provoking further investigation into the Fe3O4 analog.
Host: Yingwei Fei
- Tuesday, May 31, 2022, at 11:00 a.m. (virtual seminar; Note: Tuesday instead of Monday due to the Memorial Day holiday)
Jennifer Bergner, The University of Chicago
Title: Volatile chemistry in planet-forming disks
Abstract: Planets form within disks composed of gas, ice, and dust in orbit around young stars. The distribution of volatiles (gas+ice) within these disks profoundly impacts both the chemical and physical outcomes of planet formation-- including the delivery of prebiotic building blocks to new worlds. In this talk, I will highlight our recent advances in disentangling how organic complexity is built up during the star and planet formation sequence, the role of interstellar inheritance in setting disk volatile compositions, and the distinctive volatile chemistry at play during the planet formation epoch. These insights are gained by combining telescope observations, ice chemistry experiments, and disk simulations, each of which contributes an indispensable piece of the puzzle. Taken together, we are assembling a more complete picture of the chemical environment which regulates the formation, composition, and potential habitability of planetesimals and planets.
Host: Alycia Weinberger
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We record and publish most seminars on our YouTube Channel.