November 21, 2023

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Speaker: Eva L. Scheller, Heising-Simons Postdoctoral Fellow, Massachusetts Institute of Technology

Title: Searching for Mars’ missing carbonates

Abstract: Mars’ current frozen conditions, marked by a thin 6 mbar CO₂ atmosphere, contrast with its geological and mineralogical records of a once aqueous environment. These findings have fueled the hypothesis of a denser atmosphere on ancient Mars, raising pivotal questions about its thickness and subsequent depletion over time. On Earth, a CO₂-rich atmosphere undergoes sequestration, transforming into carbonate minerals through aqueous interactions—a process anticipated to have occurred on Mars. Despite this expectation, the paucity of carbonates detected via orbiters and rovers on Mars’ surface has posed a conundrum, informally termed as “the missing carbonates”.

Upon the Perseverance rover’s landing in Jezero Crater in February 2021, it identified carbonate compounds within the ancient ultramafic terrain and the crater’s fluvio-lacustrine deposits – unpredicted by orbital datasets. Furthermore, the Perseverance rover confirmed that Mars’ carbonate formation is predominantly governed by carbonation, dictated by the dissolution kinetics of olivine in, specifically, ultramafic terrains in the crust. The Perseverance rover’s findings not only broaden our understanding of Mars’ atmospheric loss but also provide a geochemical framework indicative of low water activity. These revelations offer a significant leap towards unraveling the fate of Mars’ sequestered atmosphere, enhancing our comprehension of planetary atmospheric evolution. Join me as I delve into these fascinating developments and edge closer to solving the Martian carbon puzzle.

Biography:

• B.Sc. in Geosciences, University of Copenhagen – 2017
• M.Sc. in Geology, Caltech – 2020
• Ph.D. in Geology, Caltech – 2022
• Heising-Simons 51 Pegasi B Postdoctoral Fellow at MIT – 2022 to now
• Member of Perseverance rover science team – 2018 to now.

About Eva Scheller