Tracing the fate of carbon and the atmospheric evolution of Mars

Creators: Hu, Renyu; Kass, David M.; Ehlmann, Bethany L.; Yung, Yuk L.

Abstract

The climate of Mars likely evolved from a warmer, wetter early state to the cold, arid current state. However, no solutions for this evolution have previously been found to satisfy the observed geological features and isotopic measurements of the atmosphere. Here we show that a family of solutions exist, invoking no missing reservoirs or loss processes. Escape of carbon via CO photodissociation and sputtering enriches heavy carbon (^(13)C) in the Martian atmosphere, partially compensated by moderate carbonate precipitation. The current atmospheric ^(13)C/^(12)C and rock and soil carbonate measurements indicate an early atmosphere with a surface pressure <1 bar. Only scenarios with large amounts of carbonate formation in open lakes permit higher values up to 1.8 bar. The evolutionary scenarios are fully testable with data from the MAVEN mission and further studies of the isotopic composition of carbonate in the Martian rock record through time.

Additional Information

© 2015 Macmillan Publishers Limited. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. Received 17 Jul 2015 | Accepted 26 Oct 2015 | Published 24 Nov 2015 Support for this work was provided by NASA through Hubble Fellowship grant #51332 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Contributions: R.H. modelled the fractionation factor of photochemical escape, developed the million-model approach, simulated the evolution scenarios and wrote the manuscript; D.M.K. provided the framework of the evolution model and modelled the fractionation factor of sputtering; B.L.E. assembled the measurements of carbonate content in rock and soil, and provided geological constraints on scenarios; Y.L.Y. provided the insight into the evolution of stellar radiation and escape rates; all authors interpreted the results and commented on the manuscript. The authors declare no competing financial interests.

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