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2014 Annual Science Report

Pennsylvania State University Reporting  |  SEP 2013 – DEC 2014

Biosignatures in Ancient Rocks - Kasting Group

Project Summary

We have been working on two things: 1) the question of whether there are plausible “false positives” for life on extrasolar planets, i.e., high abiotic O2 and/or O3 levels that might be confused with evidence for photosynthesis, and 2) hydrodynamic escape of hydrogen from H2- or H2O-rich primitive atmospheres. We are developing a two-component model to describe this process. Old single-component models evidently do not obey the diffusion limit, so are are trying to remedy that.

4 Institutions
3 Teams
8 Publications
1 Field Site
Field Sites

Project Progress

We are close to writing a paper on the false positives project. We can reproduce the apparent false positives of other groups (Hu et al., 2012; Domagal-Goldman et al., 2014; Tian et al., 2014), but we can also show that these results are based on an unphysical choice of lower boundary conditions which would not be expected to occur on a real planet.

We also have been working on a variety of other astrobiology projects which are related to the project described here in different ways. See our list of publications for late 2013-2014.

Publications

  • Claire, M. W., Kasting, J. F., Domagal-Goldman, S. D., Stüeken, E. E., Buick, R., & Meadows, V. S. (2014). Modeling the signature of sulfur mass-independent fractionation produced in the Archean atmosphere. Geochimica et Cosmochimica Acta, 141, 365–380. doi:10.1016/j.gca.2014.06.032

  • Harman, C. E., Kasting, J. F., & Wolf, E. T. (2013). Atmospheric Production of Glycolaldehyde Under Hazy Prebiotic Conditions. Orig Life Evol Biosph, 43(2), 77–98. doi:10.1007/s11084-013-9332-7

  • Kasting, J. F. (2014). Atmospheric composition of Hadean–early Archean Earth: The importance of CO. Earth’s Early Atmosphere and Surface Environment, None, 19–28. doi:10.1130/2014.2504(04)

  • Kasting, J. F., & Harman, C. E. (2013). Extrasolar planets: Inner edge of the habitable zone. Nature, 504(7479), 221–223. doi:10.1038/504221a

  • Kasting, J. F., Kopparapu, R., Ramirez, R. M., & Harman, C. E. (2013). Remote life-detection criteria, habitable zone boundaries, and the frequency of Earth-like planets around M and late K stars. Proceedings of the National Academy of Sciences, 111(35), 12641–12646. doi:10.1073/pnas.1309107110

  • Kopparapu, R. K., Ramirez, R. M., SchottelKotte, J., Kasting, J. F., Domagal-Goldman, S., & Eymet, V. (2014). HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: DEPENDENCE ON PLANETARY MASS. The Astrophysical Journal, 787(2), L29. doi:10.1088/2041-8205/787/2/l29

  • Ramirez, R. M., Kopparapu, R. K., Lindner, V., & Kasting, J. F. (2014). Can Increased Atmospheric CO 2 Levels Trigger a Runaway Greenhouse?. Astrobiology, 14(8), 714–731. doi:10.1089/ast.2014.1153

  • Ramirez, R. M., Kopparapu, R., Zugger, M. E., Robinson, T. D., Freedman, R., & Kasting, J. F. (2013). Warming early Mars with CO2 and H2. Nature Geosci, 7(1), 59–63. doi:10.1038/ngeo2000

  • PROJECT INVESTIGATORS:
    James Kasting James Kasting
    Project Investigator
  • RELATED OBJECTIVES:
    Objective 1.1
    Formation and evolution of habitable planets.

    Objective 2.1
    Mars exploration.

    Objective 4.1
    Earth's early biosphere.

    Objective 7.2
    Biosignatures to be sought in nearby planetary systems