Bethany L. Ehlmann

California Institute of Technology

2015 James B. Macelwane Medal Winner

Paul Cassak, Bethany List Ehlmann, Colette L. Heald, Matt Jackson, and Kate Maher were awarded the 2015 James B. Macelwane Medal at the AGU Fall Meeting Honors Ceremony, held on 16 December 2015 in San Francisco, Calif. The medal is for “significant contributions to the geophysical sciences by an outstanding early career scientist.”


Bethany Ehlmann has made exceptional contributions to the identification and understanding of the alteration mineralogy of Mars, linking surface composition to its geologic context and the implications for the planet’s habitable past. She has made major new mineralogical discoveries on Mars, including carbonates, clay minerals, and other aqueous alteration phases. She has demonstrated that geologic associations of these minerals suggest their production through hydrothermal and groundwater processes occurring in the shallow or middle crust. This is among the most important unanticipated discoveries of the last decade of Mars exploration, as it reveals the nature of the crustal reservoir of mineral-bound water and associated alteration phases and points us toward new terrestrial analog models of the Mars water cycle.

While her dissertation and postdoctoral work has emphasized orbital spectral data analyses from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and the Observatoire pour la Minéralogie, l’Eau, les Glaces et l’Activité (OMEGA), Bethany’s contributions to Mars rover missions began when she was an undergraduate at Washington University. She served in many indispensable mission operations roles on the Mars Exploration Rovers, Spirit and Opportunity, and honed her already formidable scientific skills by contributing to team publications in Science and Nature. Her rover involvement continues to this day with mission-critical leadership roles on the Mars Science Laboratory (MSL) rover Curiosity, including the fact that the results of her orbital data analysis influenced the landing site selection for MSL.

As evidence of Bethany’s far-ranging intellectual interests, she began in an undergraduate program for students with interests in scientific, political, cultural, and ethical issues associated with the environment. She was selected as a Rhodes Scholar, completing two master’s degrees in environmental change and management and geography at the University of Oxford before her Ph.D. in geological sciences at Brown University. Following her Ph.D., she completed a Marie Curie Fellowship at Université Paris-Sud in Orsay. Her extensive publication list (more than 65 peer–reviewed papers) includes topics in astrobiology, polar processes, terrestrial analogs, and advanced instrumentation for future landed missions.

In a field that attracts highly capable scientists, Bethany is clearly a standout, with the technical sophistication, intellectual rigor, and leadership abilities to be at the vanguard of the scientific and technical challenges that await the future of Mars and planetary exploration.

—Wendy Calvin, University of Nevada, Reno


It was a surprise and honor to receive this award. Many thanks to my nominator, Wendy Calvin, whom I’ve had the privilege of working with and learning from on two mission teams.

About 15 years ago—it does not seem so long ago—I attended my first fall AGU meeting as an undergrad. Surfing between remote sensing, biogeochemisty, mineralogy, geomorphology, and planetary sciences, I remember thinking “This is where the fun science is at.”

It remains both fun and a privilege to be part of this community today. Mars science has been an exciting scientific ride, fueled in no small part by the superb data generated by two dedicated Mars imaging spectrometer teams, OMEGA and CRISM, led by Jean-Pierre Bibring and Scott Murchie, along with numerous other amazing friends and colleagues on the Mars Exploration Rover (MER), Mars Reconnaissance Orbiter (MRO), and MSL missions. One of the lessons I’ve learned is that doing great science takes technical skills, commitment, and intuition but also surrounding yourself with a supportive community of mentors. Special thanks go to Ray Arvidson at Washington University for setting me off on this path of exploration as an undergrad, as well as to my mentors on the MER mission—I wouldn’t have found my way to planetary science without you. My thanks also go to John Boardman and Heather Viles at Oxford for honing my skills as an independent researcher and to Jack Mustard, my awesomely supportive Ph.D. adviser at Brown, who encouraged me to dive deeply into the data. Thanks also go to the cohort at Institut -d’Astrophysique Spatiale–Orsay for support during my second foray over the Atlantic and to many supportive faculty, postdoc, graduate student, and staff colleagues at the California Institute of Technology and Jet Propulsion Laboratory. Special thanks go to John Grotzinger, Ray, and Scott for writing letters in support of this citation.

Looking to the future, it is an exciting time to be in planetary science. Having at least flown by all the major bodies in the solar system, we now have to test our understanding of how planets work and evolve against data from the telescopic discoveries of exoplanets. MSL is climbing a mountain on Mars, we’re preparing to examine and sample the most primitive asteroids, and we’re gearing up to explore icy worlds with subsurface oceans. Armed with ever–expanding tools for doing science in situ, there is a revolution in understanding each time we send robotic landers and rovers to unexplored locales. I’m looking forward to the next decades of discoveries. Thank you.

—Bethany List Ehlmann, California Institute of Technology, Pasadena