International Journal of Impact of space weather on climate and Astrobiology habitability of terrestrial-type exoplanets cambridge.org/ija V. S. Airapetian1,2 , R. Barnes3, O. Cohen4, G. A. Collinson1, W. C. Danchi1, C. F. Dong5, A. D. Del Genio6, K. France7, K. Garcia-Sage1, A. Glocer1, N. Gopalswamy1, J. L. Grenfell8, G. Gronoff9, M. Güdel10, K. Herbst11, Review W. G. Henning1, C. H. Jackman1, M. Jin12, C. P. Johnstone10, L. Kaltenegger13, Cite this article: Airapetian VS et al (2019). 11 14 1 15 16 10 Impact of space weather on climate and C. D. Kay , K. Kobayashi , W. Kuang ,G.Li , B. J. Lynch , T. Lüftinger , habitability of terrestrial-type exoplanets. J. G. Luhmann16, H. Maehara17, M. G. Mlynczak9, Y. Notsu18, R. A. Osten30, International Journal of Astrobiology 1–59. https://doi.org/10.1017/S1473550419000132 R. M. Ramirez19, S. Rugheimer20, M. Scheucher21, J. E. Schlieder1, K. Shibata22, Received: 27 December 2018 C. Sousa-Silva23, V. Stamenković24, R. J. Strangeway25, A. V. Usmanov1,26, Revised: 14 May 2019 24 24 27 28 6 Accepted: 14 May 2019 P. Vergados , O. P. Verkhoglyadova , A. A. Vidotto , M. Voytek ,M.J.Way, 15 29 Key words: G. P. Zank and Y. Yamashiki astrobiology; atmospheres; biosignatures; chemistry; CME; exoplanets; flares; 1Sellers Exoplanet Environments Collaboration, NASA/GSFC, Greenbelt, MD, USA; 2Department of Physics, habitability; internal dynamics; magnetic field; American University, Washington, DC, USA; 3University of Washington, Seattle, Washington, USA; 4Lowell Center for SEP; space weather; stars; Sun Space Science and Technology, University of Massachusetts, Lowell, MA, USA; 5Department of Astrophysical Sciences, Princeton University, Princeton, NJ, USA; 6NASA Goddard Institute for Space Studies, New York, NY, USA; Author for correspondence: 7Laboratory for Atmospheric and Space Physics, University of Colorado, 600 UCB, Boulder, CO 80309, USA; V. S. Airapetian, 8 E-mail: [email protected] Department of Extrasolar Planets and Atmospheres (EPA), Institute for Planetary Research, German Aerospace Centre (DLR), Rutherfordstr. 2, 12489 Berlin, Adlershof, Germany; 9NASA/LaRC, Hampton, VA, USA; 10Department of Astrophysics, University of Vienna, Türkenschanzstr. 17, 1180, Vienna, Austria; 11Christian-Albrechts-Universität zu Kiel, Institute for Experimental and Applied Physics, Leibnizstr. 11, 24118 Kiel, Germany; 12SETI Institute, Mountain View, CA 94043, USA; 13Carl Sagan Institute, Cornell University, Ithaca, NY, USA; 14Department of Chemistry, Yokohama National University, Yokohama, Japan; 15Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899, USA; 16Space Sciences Laboratory, University of California at Berkeley, Berkeley, CA, USA; 17Subaru Telescope Okayama Branch Office, NAOJ, Asakuchi, Okayama 719-02, Japan; 18Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto, Japan; 19Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1, Tokyo 152-8550, Japan; 20Centre for Exoplanet Science, University of St. Andrews, School of Earth and Environmental Sciences, Irvine Building, North Street, St. Andrews, KY16 9AL, UK; 21Zentrum für Astronomie und Astrophysik, Technische Universität Berlin, D-10623 Berlin, Germany; 22Astronomical Observatory, Kyoto University, Sakyo, Kyoto 606-8502, Japan; 23Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; 24NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA; 25University of California, Los Angeles, CA, USA; 26University of Delaware, DE 19716, USA; 27Trinity College Dublin, Dublin, Ireland; 28NASA Headquarters, Washington, DC, USA; 29Graduate School of Advanced Integrated Studies in Human Survivability (GSAIS), Kyoto University, Kyoto, Japan and 30Space Telescope Science Institute & Johns Hopkins University, MD, USA Abstract The search for life in the Universe is a fundamental problem of astrobiology and modern sci- ence. The current progress in the detection of terrestrial-type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions. To specify the conditions favour- able for the origin, development and sustainment of life as we know it in other worlds, we need to understand the nature of global (astrospheric), and local (atmospheric and surface) environments of exoplanets in the habitable zones (HZs) around G-K-M dwarf stars including our young Sun. Global environment is formed by propagated disturbances from the planet- hosting stars in the form of stellar flares, coronal mass ejections, energetic particles and winds collectively known as astrospheric space weather. Its characterization will help in under- standing how an exoplanetary ecosystem interacts with its host star, as well as in the specifi- cation of the physical, chemical and biochemical conditions that can create favourable and/or detrimental conditions for planetary climate and habitability along with evolution of planetary internal dynamics over geological timescales. A key linkage of (astro)physical, chemical and geological processes can only be understood in the framework of interdisciplinary studies © Cambridge University Press 2019 with the incorporation of progress in heliophysics, astrophysics, planetary and Earth sciences. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo) planets will significantly expand the current definition of the HZ to the biogenic zone and provide new observational strategies for searching for signatures of life. The major goal of ")!"$" &&#% ))) $"$"$%"$#&&$"!' & %'&&"& $"$&$ %"'%(& &&#% ))) $"$"$&$ %&&#% ""$ 2 V. S. Airapetian et al. this paper is to describe and discuss the current status and recent progress in this interdiscip- linary field in light of presentations and discussions during the NASA Nexus for Exoplanetary System Science funded workshop ‘Exoplanetary Space Weather, Climate and Habitability’ and to provide a new roadmap for the future development of the emerging field of exoplanetary science and astrobiology. is habitable at its surface, not only do we need to understand Introduction the changes in the chemistry of its atmosphere due to the penetra- The recent explosion of the number of planets detected around tion of energetic particles and their interaction with constituent other stars (exoplanets, currently over 4000) by space- and molecules, but also the loss of neutral and ionic species, and the ground-based missions created a great leap in the progress of addition of molecules due to outgassing from volcanic and tectonic the fields of exoplanetary science and astrobiology. These observa- activity. These effects will produce a net gain or loss to the surface tions provide a boost to scientifically addressing one of the major pressure and this will affect the surface temperature, as well as a net questions of modern science ‘Are we alone in the Universe?’. change in molecular chemistry. Therefore, due to the complexity of Although the answer to this question is unknown, the Kepler the problem, we should work with a set of interlinked research Space Telescope’s discoveries of terrestrial-type (rocky) exoplanets questions, all of which contribute pieces to the answer, with within circumstellar habitable zones (CHZs, the regions where contributions from various disciplines involved in each topic. standing bodies of liquid water can be present on the exoplanetary To quantify the effects of stellar ionizing radiation including surface) around main-sequence stars have provided an important soft X-ray and extreme ultraviolet, EUV (100–920 Å), later step in addressing this difficult question. An ongoing issue relates referred to as XUV fluxes from superflares detected by the to how well the classical CHZ as calculated by Kasting et al. Kepler mission on exoplanetary systems, specifically, on close-in (1993) and revisited by Kopparapu et al.(2013) relates to the exoplanets around low luminosity M dwarf stars, we need to actual physico-chemical conditions required for the origin, devel- examine what do we know about the impact of SW from our opment and support of life as we know it within so-called own star on Venus, Mars and Earth, the only inhabited planet ‘Biogenic Zones’ (Airapetian et al., 2016)or‘Abiogenesis Zones’ known to us. How can we apply lessons learned from the extreme (Rimmer et al., 2018). SW events to understand how exoplanets are affected by their host With growing numbers of NASA (National Aeronautics and stars? Can heliophysics science with its methodologies and mod- Space Administration) and ESA (European Space Agency) exopla- els developed to describe the effects of solar flares, CMEs as the netary missions such as the Transiting Exoplanet Survey Satellite factors of SW, on Venus, Earth and Mars be expanded to address (TESS), the upcoming James Webb Space Telescope (JWST), the extreme conditions on exoplanets around young solar-like Characterizing ExOPlanet Satellite (CHEOPS), the PLAnetary stars and close-in exoplanets around active F, G, K and M dwarfs? Transits and Oscillations of stars (PLATO), the Atmospheric These questions are of critical importance as the major factors of Remote-sensing Infrared Exoplanet Large-Survey (ARIEL) mis- habitability of exoplanets. sions, in the relatively near term we will be better equipped In this