Hydrogen Escape across the Solar System and Beyond

PI: Mike Chaffin, LASP, University of Colorado

Abstract Hydrogen escape has played a major role in sculpting the atmospheres of the terrestrial , with the most notable examples being the dessication of and Mars. Because it can so greatly influence the composition of terrestrial atmospheres with time, it is important to understand the dynamics and escape of hydrogen in general, across solar system objects and in exoplanetary systems. Now is an opportune time to begin this synthesis, given near-continuous observation of Mars H escape by NASA’s MAVEN mission, H escape by TWINS and other near-Earth assets, the discovery of H coronas around close-in exoplanets, and the complete H escape dataset from at Venus. Beyond these observations, newly discovered phenomena that may control H escape from Mars and other planets are being explored with models, whose implications have not yet been fully integrated into observational studies or across objects. We will form an ISSI International Team to bring experts who study each of these topics together, combining experience to begin assembling a comprehensive framework for understanding H dynamics and escape across observed planets. In addition to observers, we will invite modelers of H escape to understand how the observations in hand should be interpreted, as well as how they can be used to inform studies of early Solar System escape and escape from exoplanets. The result of our team’s work will be a new understanding of hydrogen escape and atmospheric evolution in its cosmic context, at least one review article summarizing current knowledge of H escape, and greatly strengthened ties across disciplines and objects that will be essential to interpreting the planetary and exoplanetary data of tomorrow. 1 Scientific Rationale and Goals All planets continually lose hydrogen to space from their extended upper atmosphere or corona, where the atmosphere becomes collisionless and particles with sufficient energy can escape the planet. This loss has been especially significant on two solar system terrestrial planets, Venus and Mars, whose deuterium-to-hydrogen ratios are enhanced relative to the Earth and Jupiter (Villanueva et al., 2015; Donahue et al., 1982). The Earth’s loss to space has been less extreme, indicating that mechanisms operating at Venus and Mars have been ineffective in fractionating Earth’s water inventory over time (Yung et al., 1989). In addition, recent observations of close-in exoplanets have revealed extended H coronas experiencing high rates of hydrodynamic escape (Ehrenreich et al., 2015). Taken together, these observations indicate that H escape can either completely dessicate terrestrial planets (as in the case of Venus), or leave a planet relatively unaffected (Earth). Because the major process removing H from the atmosphere is different at each object (Figure 1), coordinated study is required to understand how planets retain or lose their hydrogen with time. To understand the history of the solar system, determine the factors that control planetary evolu- tion, and prioritize followup observations of potentially habitable terrestrial planets, it is important to combine knowledge of H escape and its impacts across objects and throughout time. Our ISSI team will address these objectives, drawing on experts in modeling and data analysis of the Earth, planets and exoplanets to: 1. Review knowledge of H escape mechanisms across past and present terrestrial planets and known exoplanets; and 2. Exchange data analysis and modeling techniques and tools, laying a foundation for future work on H escape at and across objects. To accomplish our aims, we will produce at least one review article summarizing the current state of knowledge of H escape across Venus, Earth, Mars, and known exoplanets. This article will break

1 Figure 1: Major escape processes at each object to be studied by the proposal team. At Venus, H escapes mostly as a result of ionospheric protons charge exchanging to neutral H with greater than escape velocity. At Earth, H escape is mostly nonthermal via the polar wind, but a significant fraction escapes thermally. At Mars, escape is thought to be completely thermal at present, with hints that other processes may exist and potentially dominate escape. On close-in exoplanets, upper atmospheric temperatures are high enough that H escapes hydrodynamically.

down disciplinary and object-specific silos, leading to new collaborations essential to understanding H escape throughout time and space. Commonalities in observables and data analysis techniques provide further justification for the collaboration between data analysts our ISSI team will provide. Star or sunlight scattered or absorbed by coronal hydrogen lines provides the only observable signature of neutral H in extended planetary coronas.1 Lyman alpha (at 121.6 nm) provides the easiest spectral target because of its intrinsic brightness, but the optical depth resulting from the line strength requires that H escape retrieval codes incorporate radiative transfer models. Such models began with a common terrestrial origin (Thomas, 1963), but have diverged in recent years, with different models employed at Venus (Chaufray et al., 2012), Earth (Waldrop and Paxton, 2013), Mars (Chaffin et al., 2014; Bhattacharyya et al., 2015), and exoplanets (Ehrenreich et al., 2015). This divergence requires closer collaboration between data analysts to ensure that models are correct and that they benefit from the latest innovations. Our ISSI team provides the necessary venue to pursue this valuable work. In addition, our objectives are motivated by multiple recent discoveries of H escape phenomena, as well as the emergence of new data analysis techniques. These new discoveries and techniques have been mostly confined to individual objects, and are summarized below for Venus, Earth, Mars, and exoplanets. 1.1 Venus Venus is the most dessicated Solar System planet with an atmosphere, having an atmospheric D/H ratio approximately 120 times the Earth value (Donahue et al., 1982). Assuming the planet began with a D/H ratio similar to the Earth, the vast majority of Venus’s early water must have been lost to space. H loss at present is nonthermal: the temperature of the Venus is too low for a substantial fraction of the thermal population to escape (Chaufray et al., 2012). Instead,

1Neutral H densities are too low for present techniques to measure, and most planetary neutral gas mass spectrometers suffer from significant contamination by terrestrial water, masking any planetary H signal.

2 H escaping from the Venus atmosphere is produced by nonthermal charge exchange of ionospheric protons, which creates a hot neutral component (Hodges, 1999). The result of this process was first correctly interpreted by Anderson, (1976), who ascribed the slope change observed in Lyman alpha brightness profiles to the presence of two populations at different temperatures. This charge exchange process is expected to be active at other planets and on exoplanets, making inclusion of Venus and Venus experts in our study essential. Our team has the necessary expertise to summarize knowledge of Venus and apply it to other objects. The most recent interpretation of Venus H coronal data gathered by Venus Express was performed by team member Jean-Yves Chaufray (Chaufray et al., 2012). In addition, team member John Clarke is the PI of NASA sounding rocket VESPR, which targeted D/H observations of the Venus atmosphere (Clarke et al., 2013). Team member Hannes Gr¨ollerhas studied the nonthermal processes populating the Venus corona, extending the work of Hodges, (1999) (Gr¨olleret al., 2015). These team members will ensure that the processes operating at Venus are correctly understood and applied to the other planets in our study. 1.2 Earth Earth is massive enough and far enough from the to have avoided planet-altering H escape, but H loss at Earth is still active, variable, and in some cases poorly understood. Loss from earth proceeds from both thermal and nonthermal channels, with perhaps 70% of the loss due to ambipolar electric fields at high latitude accelerating protons outward in a polar wind, and 30% due to thermal escape of hydrogen (Yung et al., 1989). Unlike Venus, Earth’s higher thermospheric temperatures mean that it experiences thermal H loss from the high-energy tail of the H velocity distribution. Both of these loss processes may be efficient on exo-. Our team includes Kanako Seki, an expert in proton escape along the polar wind, and Lara Waldrop, an expert in Earth coronal dynamics and data analysis. They provide us with the expertise needed to generalize the insights gleaned at Earth to other planets. Recent data analysis at Earth has yielded new techniques and surprising discoveries that moti- vate increased collaboration. Team member Lara Waldrop has led an effort to develop tomographic inversion techniques that, by contrast with traditional methods, make no a priori assumptions about coronal structure (Ren, Waldrop, and Kamalabadi, 2016). These techniques are already being applied to Earth data, for example from the TWINS mission (Zoennchen et al., 2010). As part of our team effort, we will discuss applying these techniques to planetary data beyond Earth. Another discovery made at Earth by Waldrop’s team is the presence of significant unexplained hot H at solar minimum (Qin and Waldrop, 2016). The source of the hot H is unknown, but is thought to be most visible at solar minimum due to the lower O densities present at these times, which results in incomplete thermalization of a hot H component. This hot component may significantly influence escape rates on Earth and Earth-like planets throughout the universe. Meanwhile, polar wind studies at Earth con- tinue, with team member Kanako Seki leading a team whose goal is understanding the fundamental processes that control this important escape channel (Kitamura et al., 2015; Seki, 2001). As part of our team’s work, we will discuss the influence of varying magnetic field strength and solar drivers on the magnitude of polar wind escape, seeking to understand in broad terms how a polar wind might act on early Mars or an exo-Earth with an Earth-like dipole magnetic field. 1.3 Mars Mars represents a case intermediate to Venus and Earth, in which H escape has greatly fractionated but not completely removed the planet’s water inventory. Analysis of D/H ratios in near-surface water indicate that perhaps five-sixths of the inital Martian water inventory has been lost to space (Villanueva et al., 2015). Loss from Mars is expected to be principally via thermal escape due to the planet’s low gravity, despite Mars having similar thermospheric temperatures to Venus. However, the recent discovery of seasonally variable H escape by team leader Mike Chaffin (Chaffin et al., 2014)

3 and team member John Clarke (Clarke et al., 2014) indicates that new processes may be required to explain the seasonal variability. These may include seasonal presence of a hot component similar to that at Venus, or increased transport in the lower atmosphere resulting in a high-altitude water source for escaping H (Chaffin et al., 2017). Either explanation is of potential interest to the broad H escape community assembled by this ISSI team. Seasonally variable escape is continuing to be observed by team members Chaffin, Clarke, and Chaufray with data from NASA’s MAVEN mission (Jakosky et al., 2015), and by Clarke with Hubble Space Telescope observations. In addition, team member Hannes Gr¨ollerhas begun perform hot H escape simulations for Mars, exploring for this planet mechanisms known to be active and important on Venus. As part of our ISSI work, we will discuss applying these new simulations, and knowledge of seasonally variable escape more generally, across all solar system and exoplanets. Mars is potentially a stone for understanding atmospheric escape, with thermal and non- thermal escape active at present and in the past, an early period of hydrodynamic escape investigated by team member Feng Tian (Tian, Kasting, and Solomon, 2009), and the potential for polar wind escape from an early Martian global dipole field or from cusps of crustal magnetic fields today. As part of our team effort we will discuss the ways in which work done on Earth and Venus can inform understanding of Mars H escape, and how Mars can inform planetary escape in general, especially from low-mass exoplanets. This last is of particular importance because low-mass planets may be the most common type of planet in the universe. 1.4 Exoplanets Less is known about H escape from exoplanets than is known for any terrestrial planet, making use of terrestrial analogues essential for understanding exoplanetary escape. At the same time, close-in exoplanets are exposed to conditions not found on any solar system planet, probing a vastly different escape regime useful for understanding atmospheric escape in general. Because of this, the cross- disciplinary exchange we propose with this ISSI team is particularly important. Furthermore, because planets dessicated by H escape are unlikely hosts for life, the work we propose will help to inform the prioritization of potentially habitable exoplanets for followup, determining the conditions under which planets are expected to have experienced significant H escape. Broad inclusion of exoplanet scientists in our team will enable solar system lessons to be applied to exoplanet studies, and vice-versa. Highly irradiated exoplanets in close in orbits have been observed by team members David Ehrenreich (Ehrenreich et al., 2015) and Kevin France (Kulow et al., 2014), with the incident EUV instellation measured and reconstructed for this and other stars by France’s group (France et al., 2016; Loyd et al., 2016; Youngblood et al., 2016). Modeling studies of H escape from close-in exoplanets have been performed by team members Feng Tian (Tian et al., 2005; Tian, 2015), Roger Yelle (Yelle, 2004), and Tommi Koskinen (Koskinen, Aylward, and Miller, 2007; Koskinen et al., 2014). This group captures the expertise necessary to achieve our project goals of exchanging H escape models and observations between the solar system and exoplanet communities. 2 Expected Output Our team has two major objectives: first, to review knowledge of escape mechanisms across objects, producing a paper summarizing current knowledge of H escape; and second, to exchange data analysis and modeling techniques and tools, applying insights gained on individual objects to other planets. Both efforts will stimulate scientific discovery, improving knowledge of how H escape impacts planetary atmospheric evolution today and throughout time. We will determine the ways in which the terres- trial planets are useful analogues for one another and for exoplanets, and reincorporate knowledge of hydrodynamic escape established for exoplanets into the planetary literature. In addition, we expect new collaborations between team members to result from our work, which will endure far beyond the formal end date of our team.

4 3 Added Value of ISSI ISSI provides an ideal venue for achieving our team goals. Participating team members are scattered across many institutions, countries, and scientific disciplines, and typically attend different conferences, making collaboration without ISSI support difficult or impossible. In addition, our team goals are highly compatible with the mission of ISSI to support and advance space research. By allowing our team to share expertise and techniques across objects, ISSI will enable a deeper understanding of H escape across the solar system and throughout the universe. 4 Team Members Our confirmed team members include experts in modeling and data analysis of H escape from Venus, Earth, Mars, and exoplanets. Confirmed team members and their core competencies are:

Mike Chaffin (Mars modeling and observa- Tommi Koskinen (exoplanet modeling and • • tions) observations) John Clarke (Venus & Mars observations) Kanako Seki (Earth polar wind modeling • • Jean-Yves Chaufray (Venus & Mars model- and observations) • ing and observations) Feng Tian (early Solar System modeling) • David Ehrenreich (exoplanet observations) Lara Waldrop (Earth observations) • • Kevin France (exoplanet observations) Roger Yelle (Solar System & exoplanet mod- • • Hannes Gr¨oller(Venus & Mars modeling) eling and observations) • 5 Project Schedule We propose three meetings of four days each. Because the team has participation from the US, Europe, and Asia, two meetings will take place at ISSI in Bern, with one occurring at ISSI in Beijing. During the first meeting taking place at ISSI/Bern before the end of 2017, team members will summarize their work constraining or modeling H escape at Venus, Earth, Mars, and exoplanets. We will make note of differences in methodology and identify areas where future modeling or data analysis could more closely align approaches to studying H escape across these bodies. We will pay particular attention to techniques developed for individual objects that may be usefully applied to other objects, such as applying tomographic techniques developed at Earth to Mars. We will develop a list of action items, including data analysis and modeling tasks that will inform cross-object comparisons. In addition, we will outline a review paper summarizing current knowledge of H escape across the solar system and exoplanets. At the second and third meetings, scheduled in Spring/Summer 2018 (Beijing) and Fall 2018 (Bern), we will exchange the results of new simulations and analyses, and push forward writing of the review paper. We expect to submit our review paper shortly after our third meeting and continue our collaborations after the formal ISSI team work is concluded. We further expect that our cross-object comparison and modeling work may result in additional papers, for example from applying Earth- developed tomographic inversion techniques to Mars atmosphere data. A detailed plan for any such papers will emerge from our first meeting. 6 Facilities and Financial Support Required We request that ISSI provide meeting space, per diem, and accomodation for 10 team members, with one of Hannes Gr¨olleror Roger Yelle (TBD) paying for their own lodging and per diem from University of Arizona funds. In addition, we request travel support for the team leader, which we may assign to another member at a later date if they are unable to secure independent funding for travel. In this circumstance the team leader is prepared to pay for his own travel expenses. We request the addition of two early career team members, to be selected by the team leader from among the early career colleagues of team members.

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8 Contact Information Mike Chaffin michael.chaffi[email protected] 3665 Discovery Drive, Boulder CO 80309 USA +1 303 517 0319 / +1 303 492 6444 (fax)

John Clarke [email protected] 725 Commonwealth Avenue, Boston MA 02215 USA +1 617 353 0247 / +1 617 353 6463 (fax)

Jean-Yves Chaufray [email protected] Tour 45, Couloir 45-46, 3e et 4e ´etages(bote 102) Universit´ePierre et Marie Curie, 4 place Jussieu, 75252 Paris Cedex 05, France +33 01 80 28 50 77 / +33 01 44 27 37 76 (fax)

David Ehrenreich [email protected] Observatoire astronomique de l’Universit´ede Gen`eve-51 des Maillettes 1290 Sauverny Switzerland +41 22 379 23 90 / +41 22 379 22 35 (fax)

Kevin France [email protected] 3665 Discovery Drive, Boulder CO 80309 USA +1 303 492 1429 / +1 303 492 6444 (fax)

Hannes Gr¨oller [email protected] 3440 E Via Guadalupe, Tucson, AZ, 85716 USA +1 520 440 0449 / +1 520 621 4933 (fax)

Tommi Koskinen [email protected] 3440 E Via Guadalupe, Tucson, AZ, 85716 USA +1 520 621 6939 / +1 520 621 4933 (fax)

Kanako Seki [email protected] Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan +81 3 5841 4577 / +81 3 5841 8779 (fax)

Feng Tian [email protected] Department of Earth System Science, Tsinghua University, Beijing, China 100084 +86 010 64888708

Lara Waldrop [email protected] 5052 ECE Building, 306 North Wright St., Urbana, IL, 61801 USA +1 217 300 0957

Roger Yelle [email protected] 3440 E Via Guadalupe Tucson, AZ, 85716, USA +1 520 621 6243 / +1 520 621 4933 (fax)

9 MICHAEL CHAFFIN Laboratory for Atmospheric and Space Physics mikechaffin.com University of Colorado at Boulder michael.chaffi[email protected] RESEARCH I study volatile loss from Mars via measurements and models, focusing on H escape from the extended corona surrounding the planet. By analyzing data from ESA’s spacecraft, I discovered the time-variation of hydrogen escape from Mars, an observation which significantly changes the story of how Mars dried out over solar system history. I provided explanations for these variations with photochemical modeling that introduces new channels for H escape that oxidize Mars over time. I continue to study the H corona with MAVEN and am a co-Investigator on the Emirates Mars Mission UV spectrograph, which will arrive at Mars in 2021. PROFESSIONAL 2015-Present Research Associate, LASP EXPERIENCE 2015-Present Emirates Mars Mission Science Team September 2014 Emirates Mars Mission Science Definition Team 2015-Present CU Boulder NExSS Team Co-Investigator 2009-Present MAVEN Science Team 2009-2015 Research Assistant, CU APS Department SELECTED M. S. Chaffin, Justin Deighan, Nicholas M. Schneider, and Ian Stew- PUBLICATIONS art, Elevated atmospheric escape of atomic hydrogen from Mars in- Complete List duced by high-altitude water. Nature Geoscience, 2017. via ADS M. S. Chaffin, et al. Three-dimensional structure in the Mars H corona revealed by IUVS on MAVEN. Geophysical Research Letters, 2015. M. S. Chaffin, et al. Unexpected variability of Martian hydrogen escape. Geophysical Research Letters, 2014. J. Deighan, M. S. Chaffin, et al. MAVEN IUVS observation of the hot oxygen corona at Mars. Geophysical Research Letters, 2015. N. M. Schneider, et al. Discovery of diffuse aurora on Mars. Science, 350, Nov 2015. N. M. Schneider, et al. MAVEN IUVS observations of the aftermath of the Comet Siding Spring shower on Mars. Geophysical Research Letters, 2015. SELECTED DPS 2015: “MAVEN IUVS observations of the extended corona of ABSTRACTS Mars” Complete List CCTP2 2015: “H Escape: The Story at Mars as Revealed by MAVEN via ADS and Mars Express” AGU 2015: “Effect of Upper Atmospheric Water on Martian Photo- chemistry and Water Loss” FUNDING MDAP 2013/Testing New Paradigms of Water Escape through Mars HISTORY Express Data Analysis. One of 30 selected of 101 submitted. Wrote text, managed proposal activities with Schneider as PI of record. NASA Earth and Space Science Fellowship: Awarded 2011-2013, one of 14/73 accepted. NASA Astrobiology Institute Early Career Collaboration Award; AAS DPS Hartmann Grant; LPI Career Development Award; AAS Interna- tional Travel Grant; APS Department Fellowship, Supplemental (four time recipient); Ray Mace Smith Graduate Fellowship. EDUCATION University of Colorado, M.Sc. Spring 2012, PhD May 2015 Thesis: The H Corona of Mars Adviser: Nicholas Schneider Reed College, B.A. Physics, 2008 Thesis: Quantum Mechanics on an Ellipse TEACHING Adjunct Faculty in Physics and Astronomy Fall 2012 - Spring 2013 Front Range Community College, Westminster, CO Taught introductory algebra-based physics and astronomy in small classrooms to students from many backgrounds. Incorporated inter- active learning throughout coursework. Instructor Summer 2012 Department of Astrophysics and Planetary Science, University of Colorado, Boulder, CO Served as instructor of record at a major US research institution, incorporating interactive learning as a major part of the curriculum. See course website at http://tinyurl.com/summer12astro. OUTREACH/ APOD 26 September 2014: Images from MAVEN’s first orbit around SERVICE Mars. MAVEN Phobos Webrelease: The first ultraviolet spectral images of Phobos in almost a decade. 2012 Finalist, NASA Famelab Communication Competition. Organized 2013 Astrobiology Graduate Conference and Re- search Focus Group, managing $60,000 of NASA NAI funding. De- veloped new astrobiology communication competition format, Astrobi- ology Speaks!, in partnership with the Redpath museum. Managed APS Department website. Advised faculty committee for National Solar Observatory tenure-track search, Spring 2014. Served on graduate student admissions and comprehensive exam advi- sory committees. NASA review panel member, 2016; executive secretary, 2015. 2015 Editors Citation for Excellence in Refereeing, Geophys- ical Research Letters. SKILLS Mathematica, C/C++, Python/Cython, Julia, LATEX, IDL, HTML, SQL, Bash, SVN, git, and OpenMP/MPI for supercomputing. John Terrel Clarke

Present Position: Professor, Dept. of Astronomy and Director, Center for Space Physics Boston University 725 Commonwealth Ave Boston MA 02115 (617)-353-0247 email: [email protected]

Education: Ph.D (Physics) the Johns Hopkins University 1980 M.A. (Physics) the Johns Hopkins University 1978 B.S. (Physics) Denison University 1974

Previous 1987 - 2001: Research Scientist, University of Michigan Positions: 1985-1987: Advanced Instruments Scientist, Hubble Space Telescope Project, NASA Goddard Space Flight Center 1984-1985: Associate Project Scientist, Hubble Space Telescope Project, NASA Marshall Space Flight Center 1980-1984: Assistant Research Physicist, Space Sciences Laboratory, University of California, Berkeley

Awards/Honors: 2016 Fellow of the American Geophysical Union 2011 NASA Group Achievement Award for MAVEN Phase B 1998 University of Michigan Research Achievement Award 1996 NASA Group Achievement Award for Comet S/L-9 Jupiter Impact Observations Team 1994 University of Michigan Research Excellence Award 1994 NASA Group Achievement Awards (3) for WFPC 2: First Servicing Mission, WFPC 2 Science, WFPC 2 Calibration 1987 NASA Scientific Research Award 1980 Forbush Fellow in the Department of Physics, JHU 1974 Sigma Pi Sigma - Physics Honorary

Professional American Astronomical Society American Geophysical Union Memberships: American Assoc. for Adv. of Science Int’l Astronomical Union

Boards: NAS Committee on Astrobiology and Planetary Science (CAPS) Consulting Editor - Icarus

Research Planetary atmospheres, UV astrophysics, Interests: FUV instruments for remote observations Over 230 papers published in refereed journals, H-index = 52 Jean-Yves Chaufray Research Fellow at Laboratoire Atmospheres Milieux et Observations Spatiales, CNRS

Graduate Engineer at the Ecole Centrale de Paris (specialization : Applied Physics), 2003 DEA (French MAS) of Astronomy and Astrophysics at University Paris VII, 2004 PhD of Astronomy and Astrophysics with honors of the University Paris VI, 2007

PROFESSIONAL CHRONOLOGY PhD Student at Service d’Aeronomie du CNRS, University Pierre and Marie Curie (Paris VI), Paris, France 2004-2007, Postdoctoral Researcher Southwest Research Institute, San Antonio, Texas 2007-2009, Postdoctoral Researcher , Laboratoire de Météorologie Dynamique, Paris, France, 2009-2011, Postdoctoral Researcher, Laboratoire Atmospheres, Mileux and Observations Spatiales, Guyancourt, France 2011-2013, Research Fellow at Laboratoire Atmospheres, Mileux and Observations Spatiales, Guyancourt, France, 2013-Present

Dr. Chaufray is a planetary scientist, specialized in the study of planetary upper atmospheres and the theory of radiative transfer of resonant lines. His interests include the upper atmospheres and the escape processes on Mars and Venus, as well as the of Mercury and the Moon. He has published several papers in refereed journals regarding the modeling and data analysis of planetary exospheres and his dissertation titled “Study of the Martian exosphere and water escape: Modeling and analysis of SPICAM UV data”.

Mission activities include Co-I on Mars Express SPICAM, Bepi-Colombo PHEBUS. He is unfunded collaborator of IUVS/MAVEN and Alice/ROSETTA. He is also working on the modeling of the Martian upper atmosphere.

RECENT SELECTED PUBLICATIONS

Bhattacharyya, D. et al., 2017, Analysis and modeling of remote observations of the martian hydrogen exosphere, Icarus, 281, 264 Chaufray, J.-Y.; Deighan, J.; Stewart, A. I. F.; Schneider, N.; Clarke, J.; Leblanc, F.; Jakosky, B., 2016, Effect of the planet shine on the corona: Application to the Martian hot oxygen, J. Geophys. Res., 121, 11413 Chaufray et al, 2015 Study of the Martian cold oxygen corona from the O I 130.4 nm line by IUVS/MAVEN, Geophys. Res. Lett., 42, 9031 Deighan et al. 2015, MAVEN IUVS observation of the hot oxygen corona at Mars, Geophys. Res. Lett., 42, 9009 Chaffin et al. 2015, Three-dimensional structure in the Mars H corona revealed by IUVS on MAVEN, Geophys. Res. Lett., 42, 9001 Chaufray et al. 2015 Variability of the hydrogen in the Martian upper atmosphere as simulated by a 3D atmosphere-exosphere coupling, Icarus, 245, 282 Chaufray et al. 2015, Observation of the nightside venusian hydrogen corona with SPICAV/VEX, Icarus, 262, 1 Chaffin, M.S., J.-Y. Chaufray, I. Stewart, F. Montmessin, N.M. Schneider, and J.-L. Bertaux, Unexpected variability of Martian hydrogen escape, Geophys. Res. Lett. 41, 314-320, doi:10.1002/2013GL058578, 2014 Chaufray, J-Y., and Leblanc F., Radiative Transfer of emission lines with non-Maxwellian velocity distribution function: Application to Mercury D2 sodium lines, Icarus, 223, 975, 2013

Dr David Ehrenreich @ [email protected] ☎ +41 22 379 23 90 ✒ Observatoire astronomique de l’Université de Genève—51, chemin des Maillettes 1290 Sauverny, Switzerland

Career 2015–17 Senior Research Associate (permanent position), Université de Genève, Switzerland 2013–15 Research Associate, Université de Genève, Switzerland 2012–13 Marie-Curie fellow, Université de Genève, Switzerland 2007–12 Postdoctoral (CNES and Grivet Prize) fellow, Institut de Planétologie & d’Astrophysique de Grenoble, France 2004–07 Graduate research assistant, Institut d’Astrophysique de Paris, France 2002–03 Science data engineer, The Johns Hopkins University, Baltimore, USA

Education 2007 PhD in astrophysics from Université Pierre & Marie Curie, Paris 2004 MSc in astrophysics from Université Pierre & Marie Curie, Paris 2002 MSc in energetics & environmental engineering from EPF engineering school, Sceaux, France

Responsibilities & leadership 2017–22 Principal investigator of the European Research Council (ERC) Consolidator project FOUR ACES “Future of Upper Atmospheric Characterisation of Exoplanets with Spectroscopy” 2013– Mission Scientist of CHEOPS—Characterising Exoplanets Satellite, ESA’s S mission #1, launch 2018 and ex-officio member of the CHEOPS Core Science Team 2014–18 Leader of subproject “Atmosphere modelling” in PlanetS, a National Centre for Competences in Research (NCCR) of the Swiss National Science Foundation 2010–16 Principal investigator of 10 observation programmes on the Hubble Space Telescope 2016– Co-investigator of the Panchromatic Comparative Exoplanetary Treasury Program on the Hubble Space Telescope (498 HST orbits = 34 days-worth of exoplanet data) 2016– Science team member of the E-ELT/HIRES spectrograph “Exoplanets & circumstellar discs” working group 2016– Collaborator of the HARPS-North Consortium 2015– Principal investigator of a multi-site observation programme to characterize exoplanetary atmospheres with high-resolution spectroscopy (total of 34 nights of observations) 2012– Leader of workpackage “Atmospheric characterisation follow-up” for the science preparation of ESA’s PLATO 2008–17 Science team member of the SOPHIE Exoplanet Search Consortium 2007–13 Principal investigator of 6 observation programmes on the ESO Very Large Telescope (total of 16 nights) 2002–03 Member of the science data processing team for NASA, CNES and CSA’s FUSE mission

Selected grants, awards & distinctions 2016 Consolidator grant (2M€) of the European Research Council (ERC) 2012 Marie-Curie Intra-European Fellowship for Career Development (200k€) 2011 Grand Prix Pierre & Cyril Grivet from the French Académie des Sciences 2009 French Space Agency (CNES) postdoctoral fellowship (120k€)

Publications 92 articles accepted in international peer-reviewed journals, including 13 as first and 10 as second author 4,100+ citations H-index = 36 (source: NASA ADS) Curriculum Vitae

Kevin France

Laboratory for Atmospheric and Space Physics University of Colorado, UCB 600 3665 Discovery Dr. Boulder, CO 80309, USA

Office: Room N214 – SPSC Room D219 – Duane Phone: 303-492-1429

Email: [email protected] www: http://cos.colorado.edu/~kevinf/

Education: Ph.D. – Astrophysics, Johns Hopkins University, 2006 Advisor: Paul D. Feldman Title: “Far-Ultraviolet Molecular Hydrogen Fluorescence in Photodissociation Regions” B.A. – Physics and Astronomy, Boston University, 2000 magna cum laude with Distinction, College Prize in Astronomy

Professional Position: 2015 – present: Assistant Professor, Department of Astrophysical and Planetary Sciences & LASP – University of Colorado

Science Team/Group Affiliations: o Voting Member and UV spectrograph (LUMOS) lead – LUVOIR Surveyor Science and Technology Definition Team o Principal Investigator – University of Colorado UV Rocket Group o Principal Investigator – Colorado Ultraviolet Transit Experiment, NASA-funded CubeSat mission o Principle Investigator – MUSCLES Treasury Survey, Hubble o HST-Cosmic Origins Spectrograph Science Team o HST-Cosmic Origins Spectrograph Instrument Development Team o Referee – The Astrophysical Journal / Letters, Applied Optics, Icarus o Reviewer – NASA Postdoctoral Program, NASA NSTRF, NASA APRA o Hubble Space Telescope Time Allocation Panel Reviewer o University of Colorado Apache Point Observatory Time Allocation Committee Hannes Gröller 3440 E Via Guadalupe – Tucson, AZ, 85716 T +1 (520) 440-0449 B [email protected] •

Current Position Assistant Staff Scientist at the Lunar and Planetary Laboratory Tucson, AZ University of Arizona since January 2013 in the group of Dr. Roger Yelle Education Doctoral program in Natural Sciences (Physics) Graz, Austria Karl-Franzens University August 2008 – August 2012 (graduated with distinction) University course MSc Space Sciences (Space Physics) Graz, Austria Karl-Franzens University September 2003 – July 2008 (graduated with distinction) Bachelor program for Telematics Graz, Austria University of Technology October 2000 – August 2003 Secondary College for Electrical Engineering Pinkafeld, Austria HTBL-Pinkafeld September 1994 – June 1999 Special Training Focus on Control Engineering (graduated with distinction) PhD Thesis title: Monte-Carlo Simulation of the hot atom corona around terrestrial planets supervisors: Univ.-Prof. Helfried Biernat and Dr. Helmut Lammer censor: Univ.-Prof. Helfried Biernat and Dr. Odile Dutuit Master Thesis title: Monte-Carlo Modelling of Atmospheric Constituents Created by Photochemical Processes supervisors: Dr. Helmut Lammer and Univ.-Prof. Helfried Biernat Participation and Experience ISSS-10 Banff, Canada 10th International School/Symposium for Space Simulations July 2011 Summer School Alpbach Alpbach, Austria Astrobiology July 2007 8th ESA Student Parabolic Flight Campaign Bordeaux, France July 2005 AURORA - Student Design Contest Barcelona, Spain Category: new enabling technologies July 2003 Special Skills programming languages: Fortran, Python, IDL, C++, Matlab, Visual Basic, IRAF, PyRAF telescope certifications: Kuiper 61" Telescope operating systems: MS Windows, OS X, and Linux languages: German (first language) and English Tommi Koskinen

Lunar and Planetary Laboratory University of Arizona 1629 E. University Blvd. Tucson, AZ 85721–0092 email: [email protected] oce: +15206216939

Employment Associate Sta↵ Scientist Lunar and Planetary Laboratory, University of Arizona, 2014–

Participating Scientist on the Cassini mission, 2014–2017

Post-Doctoral Research Associate Lunar and Planetary Laboratory, University of Arizona, 2009–2014

Honorary Research Associate Department of Physics and Astronomy, University College London, 2009–

Education PhD in Astrophysics, University College London, November 2008 Thesis title: The Stability of Short-Period Extrasolar Giant Planets Supervisors: Prof. Alan D. Aylward, Dr. Serena Viti

MSci in Astrophysics (First Class Honours), University College Lon- don, 2003 Project Report: Modelling Infrared Emission from Planet Forming Dusty Disks

Prizes Jon Darius Memorial Prize for Outstanding Postgraduate Research in Astron- omy, University College London, 2008 Selected publications Koskinen, T. T., Yelle, R. V., Lavvas, P., Cho, J-Y. K., Electrodynamics on extrasolar giant planets, ApJ, 796, 16 (2014)

Lavvas, P., Koskinen, T. T., Yelle, R. V., Electron densities and alkali atoms in exoplanet atmospheres, ApJ, 796, 15 (2014) Koskinen, T. T., Lavvas, P., Harris, M. J., Yelle, R. V., Thermal escape from extrasolar giant planets, Phil. Trans. R. Soc. A, 372, 20130089 (2014) Koskinen, T. T., Harris, M. J., Yelle, R. V., Lavvas, P., The escape of heavy atoms from the of HD209458b. I. A photochemical-dynamical model of the thermosphere, Icarus, 226, 1678–1694 (2013) Koskinen, T. T., Yelle, R. V., Harris, M. J., Lavvas, P., The escape of heavy atoms from the ionosphere of HD209458b. II. Interpretation of the observations, Icarus, 226, 1695–1708 (2013) Koskinen, T. T., Yelle, R. V., Lavvas, P., Lewis, N. K., Characterizing the thermosphere of HD209458b with UV transit observations, ApJ, 723, 116-128 (2010) Koskinen, T.T., Aylward, A.D., Miller, S., A Stability Limit for the Atmo- spheres of Giant Extrasolar Planets, Nature, 450, 845-848 (2007) Kanako Seki CV

Kanako SEKI Professor, Graduate School of Science, the University of Tokyo Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, JAPAN.

EDUCATION PhD, Science, University of Tokyo, Japan, 2000 MA, Science, University of Tokyo, Japan, 1997 BA, Science, University of Tokyo, Japan, 1995 PROFESSIONAL ACTIVITIES Professor, Graduate School of Science, University of Tokyo (2015-present) Associate Professor, Solar-Terrestrial Environment Laboratory, Nagoya University (2002-2015) JSPS (Japan Society for the Promotion of Science) Research Fellow (PD), University of Tokyo (2000-2002) Graduate Research Assistant, Los Alamos National Laboratory (1999) JSPS Research Fellow (DC1), University of Tokyo (1997-2000) PROFESSIONAL SOCIETIES: American Geophysical Union Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS) Japanese Society for Planetary Sciences HONORS AND AWARDS: Excellent Reviewer Award for JSPS Research Fellowship for Young Scientists 2014 Young Scientists' Prize, The Commendation for Science and Technology by the Japanese Minister of Education, Culture, Sports, Science and Technology, 2011 AGU Fred L. Scarf Award, 2001 SGEPSS Obayashi Shorei Award, 2001 PROFESSIONAL COMMITTEE ASSIGNMENTS: Representatives of Japan Geoscience Union selected from the Space and Planetary Sciences Section (2014-present) Associate Editor of Journal of Geophysical Research – Space Physics (2008-2009) SGEPSS Steering Committee (2005-2007) SELECTED PEER-REVIEWED PUBLICATIONS (from Total of 99): 1. K. Seki, et al., A review of general physical and chemical processes related to plasma sources and losses for solar system magnetospheres, Spa. Sci. Rev., 192(1), 27-89, 2015. 2. N. Kitamura, K. Seki, et al., Limited impact of escaping photoelectrons on the terrestrial polar wind flux in the polar cap, Geophys. Res. Lett., 42, doi:10.1002/2015GL063452., 2015. 3. Seki, K., et al., Effects of the surface conductivity and the IMF strength on the dynamics of planetary ions in Mercury's magnetosphere, J. Geophys. Res., 118, DOI: 10.1002/jgra.50181, 2013. 4. C. C. Chaston, and K. Seki, Small-Scale Auroral Current Sheet Structuring, J. Geophys. Res., 115, A11221, doi:10.1029/2010JA015536, 2010. 5. Y. Yao, K. Seki, et al., Statistical properties of the multiple ion band structures observed by the FAST satellite, J. Geophys. Res., 113, A07204, doi:10.1029/2008JA013178, 2008. 6. Ozima, M., K. Seki, N. Terada, Y. N. Miura, F. A. Podosek, and H. Shinagawa, Terrestrial nitrogen and noble gases in lunar soils, Nature, 436(7051), 655-659, 2005. 7. Seki, K., et al., Comparative study of outer-zone relativistic electrons observed by AKEBONO and CRRES, J. Geophys. Res., 110, doi: 10.1029/2004JA010655, 2005. 8. Seki, K., M. Hirahara, M. Hoshino, T. Terasawa, et al., Cold ions in the hot plasma sheet of Earth’s magnetotail, Nature, 442(6932), 589-592, 2003. 9. Seki, K., R. C. Elphic, M. Hirahara, T. Terasawa, and T. Mukai, On Atmospheric Loss of Oxygen Ions from Earth Through Magnetospheric Processes, Science, 291(5510), 1939-1941, 2001. 10. Seki, K., et al., Statistical properties and possible supply mechanisms of tailward cold O+ beams in the lobe/mantle regions, J. Geophys. Res., 103(A3), 4477-4490, 1998. Feng Tian Department of Earth System Science, Tsinghua University, Beijing, China 100084 [email protected] Education: 2005 Ph.D Astrophysical and Planetary Sciences University of Colorado at Boulder 2003 M.S. Astrophysical and Planetary Sciences University of Colorado at Boulder 2000 M.S. Astrophysics Beijing University 1997 B. S. Astronomy Beijing University

Appointments: 2012— Professor Tsinghua University 2010—2014 Bairen Research Scientist NAOC 2009—2011 Research Associate II University of Colorado 2008—2009 Postdoc Research Associate MIT 2006—2008 NASA postdoctoral fellow NASA Astrobiology Institute 2005—2006 Research Associate I (Postdoc) University of Colorado 2001—2005 Research Assistant University of Colorado

Research Interests: Planetary Evolution, Planet Habitability, Comparative Planetology

Professional Services: Vice President of IAMAS-ICPAE (Elected 2015), Secretary of IAU Commission F2 (Exoplanets and the Solar system, Elected 2017), Editorial Board Member of Astrobiology, Advisory Board Member of ELSI EON Program, Primary Convener of AGU Special Session "Planetary Atmospheres and Evolution" since 2008, Principal Investigator of ISSI Astrobiology team (2015-2017).

Selected Publications (Total>45, Total Citations>1000): F. Tian, O.B. Toon, A.A. Pavlov, H. De Sterck. Transonic Hydrodynamic Escape of Hydrogen from Extrasolar Planetary Atmospheres. ApJ, 621, 1049-1060 (2005). F. Tian, O.B. Toon, A.A. Pavlov, H. De Sterck. A Hydrogen-Rich Early Earth Atmosphere. Science 308, 1014-1017 (2005). F. Tian, J.F. Kasting, H. Liu, R.G. Roble. Hydrodynamic planetary thermosphere model:. 1. The response of the Earth’s thermosphere to extreme solar EUV conditions and the significance of adiabatic cooling. J. Geophys. Res., 113, E05008 (2008). F. Tian, J.F. Kasting, S.C. Solomon. Thermal Escape of Carbon from the Early Martian Atmosphere. GRL 36, L02205, (2009). F. Tian, M.W. Claire, et al. Photochemical and Climate Consequences of Sulfur Outgassing on Early Mars. Earth and Planetary Science Letters 295, 412 (2010). F. Tian, J.F. Kasting, K. Zahnle. Revisiting HCN formation in Earth's early atmosphere. Earth and Planetary Science Letters 308 417–423 (2011). F. Tian. Atmospheric Pressure and CO2 Concentration of Potential Habitable Planet HD40307g. Science in China--Earth Sciences 43, 2099 (2013). F. Tian. Conservation of total escape from hydrodynamic planetary atmospheres. Earth and Planetary Science Letters 379, 104 (2013). F. Tian et al. Atmosphere Escape and Climate Evolution of Terrestrial Planets. pp. 567–581 in Comparative Climatology of Terrestrial Planets. Univ. of Arizona, Tucson, DOI: 10.2458/azu_uapress_9780816530595-ch23 (2013). F. Tian, et al. High Stellar FUV/NUV Ratio and Oxygen Contents in the Atmospheres of Potentially Habitable Planets. Earth and Planetary Science Letters 22, 27 (2014). F. Tian. Atmospheric Escape from Solar System Terrestrial Planets and Exoplanets. Annu. Rev. Earth Planet. Sci. 43:15.1–15.18. (2015). F. Tian, and S. Ida. Water Content of Earth-mass Planets around M dwarfs. Nature Geoscience 8, 177-180 (2015). F. Tian. Observations of Exoplanets in Time-Evolving Habitable Zones of Pre-Main-Sequence M dwarfs. Icarus 258, 50-53. (2015). F. Tian. History of Water Loss and Atmospheric O2 Buildup on Rocky Exoplanets near M Dwarfs. Earth and Planetary Science Letters 432, 126-132 (2015). T. Li, F. Tian, Y. Wang, W. Wan, X. Huang. Distinguishing a Hypothetical Abiotic Planet-Moon System from a Single Inhabited Planet. ApJL 817, L15 (2016). Y. Wang, F. Tian, T. Li, Y. Hu. On the Detection of Carbon Monoxide as an Anti-biosignature in Exoplanetary Atmospheres. Icarus 266, 15-23 (2016). J. Zhao and F. Tian. DR-Induced Escape of O and C from Early Mars. Icarus 284, 305-313 (2017). 1 Lara Suzon Waldrop

CONTACT 5052 ECE Building E-mail: [email protected] INFORMATION 306 North Wright St. Voice: (217) 300-0957 Urbana, IL, 61801 USA

RESEARCH Optical and radar remote sensing of the terrestrial upper atmosphere INTERESTS Computational modeling of radiative processes Space plasma diagnostics

PROFESSIONAL University of Illinois, Urbana-Champaign, IL PREPARATION Department of Electrical and Computer Engineering Postdoctoral Research, 2004 - 2007 Boston University, Boston, MA Ph.D., Department of Astronomy, January 2004 B.A., Department of Astronomy, May 1997 B.A., Department of Psychology (Neurophysiology), May 1997

RECENT University of Illinois, Urbana-Champaign, IL APPOINTMENTS Department of Electrical and Computer Engineering Coordinated Science Laboratory Assistant Professor 2014 - present Research Scientist 2008 - 2014 Visiting Lecturer 2008 - 2009, 2011-2014 National Science Foundation, Arlington, VA Expert 2010 - 2011 Division of Atmospheric and Geospace Sciences

SIGNFICANT Qin, J., and L. Waldrop, “Non-thermal hydrogen atoms in the terrestrial upper thermo- PUBLICATIONS sphere”, Nature Communications, 7, 13655, 2016.

Waldrop, L.S., and L. Paxton, “Lyman alpha airglow emission: implications for atomic hy- drogen geocorona variability with solar cycle”, Journal of Geophysical Research (Space Physics), 118, 5874-5890, 2013. Garzon, D., C. Brum, L. Waldrop, R. Kerr, E. Echer, N. Aponte, M. Sulzer, and S. Gonzalez, “Response of the topside ionosphere over Arecibo to a moderate geomagnetic storm”, Journal of Atmospheric and Solar Terrestrial Physics (JASTP),73:11, 1568-1574, 2011. Waldrop, L., R. Kerr, and P. Richards, “Photoelectron impact excitation of OI 8664 A˚ emis- sion observed from Arecibo Observatory”, Journal of Geophysical Research (Space Physics), 113, A01303, 2008. Waldrop, L.S., E. Kudeki, S.A. Gonzalez, M.P. Sulzer, M. Butala, and F. Kamalabadi, “Deriva- tion of neutral oxygen density under charge exchange in the topside ionosphere”, Journal of Geophysical Research (Space Physics), 111, A11308, 2006. March 20, 2017 ROGER V. YELLE Full Professor Department of Planetary Sciences and The Lunar and Planetary Laboratory University of Arizona Voice: 520-621-6243 Tucson, AZ 85721 Fax: 520-621-4933 Email: [email protected] Yelle studies the aeronomy of planetary atmospheres. He has done important work in the study of chemistry, thermal structure, and escape processes from the planets and their satellites with atmospheres. Yelle has constructed and published models for the upper atmospheres of Pluto, Titan, Mars, and close-in extra-solar planets. He is a member of the Cassini Ion Neutral Mass Spectrometer team and Interdisciplinary Scientist on the MAVEN mission and was a Voyager UVS team member and a member of the MICAS team on DS1.

SELECTED BIBLIOGRAPHY 1) R. V. Yelle and F. L. Roesler, Geocoronal Balmer Alpha Line Profiles and Implications for the Exosphere, J. Geophys. Res., 90, 7568, 1985. 2) R. V. Yelle and B. R. Sandel, Uranian H Ly- Emissions: The Interstellar Wind Source, Geophys. Res. Letters, 13, 1, 1986. 3) R. V. Yelle, A New Approach to Resonance Line Scattering in Planetary Atmospheres, Ap. J., 332, 514, 1988. 4) R. V. Yelle, and J. I. Lunine, Evidence for a Molecule Heavier than Methane in the Atmosphere of Pluto, Nature, 339, 288, 1989. 5) R. V. Yelle, Non-LTE Models of Titan's Upper Atmosphere, Ap. J., 383, 380, 1991. 6) R. V. Yelle, F. Herbert, B. R. Sandel R. J. Vervack Jr.and T. M. Wentzel, The Distribution of Hydrocarbons in Neptune's Upper Atmosphere, Icarus, 104, 38-59, 1993. 7) R. V. Yelle, L. A. Young, R. Vervack, Jr., R. E. Young, L. Pfister, and B. R. Sandel, The Structure of Jupiter's Upper Atmosphere: Predictions for , J. Geophys. Res., 101,2149-2161, 1996. 8) R. V. Yelle, Aeronomy of Extra-Solar Giant Planets at Small Orbital Distances, Icarus, 170, 167-179, 2004. 9) Koskinen, T. T., R. V. Yelle, D. Snowden, P. Lavvas, B. R. Sandel, F. J. Capalbo, Y. Benilan, and R. A. West (2011), The and Thermosphere of Titan Revealed by Cassini/UVIS Stellar Occultations, Icarus 216, 507–534. 10) Gröller, H, R V Yelle, T Koskinen, F Montmessin, G LaCombe, N M Schneider, J Deighan, A I F Stewart, S K Jain, M S Chaffin, M M J Crismani, A Stiepen, F Lefèrve, W E McClintock, J T Clarke, G M Holsclaw, P R Mahaffy, S W Bougher, B M Jakosky (2015). Probing the Martian Atmosphere with MAVEN/IUVS Occultations, Geophys. Res. Letters, 42, 9064-9070.