2025 Barringer Medal for Sarah Stewart

Sarah is a Professor at Arizona State University's School of Earth and Space Exploration. Before this, she was tenured faculty at both the University of California, Davis, and Harvard University. Her academic journey began at Harvard, where she earned two A.B. degrees in Astrophysics and Physics in 1995. Sarah then pursued a Ph.D. in Planetary Science from Caltech under the supervision of Tom Ahrens, completing her degree in 2002. Later, she held a G. K. Gilbert postdoctoral fellowship at the Carnegie Institution of Washington. This foundation equipped Sarah with the skills and deep understanding necessary for her groundbreaking work.

Sarah's achievements are numerous. Beyond the Barringer Medal we celebrate today, Sarah has received a MacArthur “Genius” Fellowship, the Urey Prize, and a Presidential Early Career Award for Scientists and Engineers. She is a Fellow of the American Association for the Advancement of Science and the American Physical Society. She has advised and mentored a dozen graduate students, nine postdoctoral fellows, and many undergraduates. Sarah cares about the people who do research, in addition to research itself. She has also led or co-led over 20 grants from NASA, the Army Research Office, the Department of Energy, and the National Science Foundation.

Sarah's work is best known for two things: her fiendishly complicated shock physics experiments and her mastery of numerical impact modeling. This marriage of methods sets her apart from most other people who study planetary cratering. And this dual approach is part of the secret sauce that empowers Sarah and her group to make such meaningful contributions. For example, numerical impact models struggle with the limited quality of equations of state and constitutive models, which describe how materials behave under extreme conditions. Sarah tackles this limitation head-on. When gas gun experiments cannot reach the needed pressures and temperatures, she turns to Z machine experiments. Sarah and her team analyze these innovative shock physics experiments to derive new equations of state. These revisions aren't just minor tweaks; these new equations of state fundamentally advance our knowledge of material behavior. Her research group then takes these improved equations of state and meticulously integrates them into numerical impact models. This blend of shock experiments and numerical modeling has transformed how we think about, for example, melting and vaporization during planet formation.

Some of Sarah's highest-impact work centers on the Earth-Moon system. In 2012, she and Matija Cuk published a pivotal paper in Science. They proposed that the Moon formed via a giant impact into a fast-spinning Earth, followed by a period of resonant despinning. This scenario successfully explains the isotopic similarities between the Earth and Moon, though other scenarios have been proposed. Since then, Sarah's group has modeled the aftermath of the Moon-forming impact in exquisite detail, which led Sarah's group to coin the term “synestia” to describe the configuration of the Earth after a high-angular-momentum giant impact. Sarah's ongoing research is rewriting the creation story for the planet we all call “home.”

In addition to her prolific research output (nearly 100 peer-review publications cited >7000 times), she served as an associate editor for the Journal of Geophysical Research—Planets, as President of the Planetary Sciences Section of the American Geophysical Union, and as a member of the Committee on Astrobiology and Planetary Science of the National Academies of Sciences, Engineering and Medicine (NASEM). Sarah has been a committee member or reviewer for multiple NASEM and Department of Energy reports, including as a reviewer for the most recent Decadal Survey of Planetary Science and Astrobiology.

Sarah excels in bridging disparate fields. She connects materials science, high-energy-density physics, and planetary science. This interdisciplinary approach enables Sarah to unlock insights into impact phenomena that would otherwise be unobtainable. She sees connections where others see boundaries.

Sarah champions collaboration. This propensity applies to both her research and her involvement in the community. A prime example is her founding of impacts.wiki. This community project aims to advance open science practices in the cratering community and to identify strategic needs. Today, Sarah is one of the few people training the next generation of impact experimentalists. She has recognized this training deficit as a risk to the long-term health of the impact field. Sarah has volunteered significant time and expertise to mitigate this risk. This selfless endeavor benefits not just planetary science, but the broader shock physics community. Sarah's focus on collaboration and cross-disciplinary work propels both her research and the scientific community forward.

I would be remiss not to mention Sarah's extensive public outreach. She advised on an exhibit at the Harvard Museum of Natural History, acted as the science advisor for an educational video series, and served as a subject-matter expert or interviewee on an IMAX film and various documentaries. Her TED Salon talk, “Where did the Moon come from? A new theory,” has been viewed more than 3 million times.

In closing, Sarah's research has undeniably deepened our understanding of impact phenomena. Sarah has fundamentally advanced our knowledge of impact processes at spatial scales that range from experiments you can hold in the palm of your hand to the giant impacts that make or break planets. But, Sarah is more than a brilliant researcher; she is a pillar of the planetary science community. This is the context in which Sarah has most directly affected my life for the better. I look forward to her future breakthroughs in impact cratering and planetary science. But, most of all, I look forward to her continued leadership in the planetary cratering community: building community, strengthening community, and unifying the community.