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1. On the plausibility of methane detections on Mars in the light of the ExoMars/TGO results

Author

Viscardy, Sébastien, Robert, Séverine, Erwin, Justin, Thomas, Ian R., Daerden, Frank, Neary, Lori, Piccialli, Arianna, Trompet, Loïc, Willame, Yannick, and Vandaele, Ann Carine

Abstract

As a potential biomarker, Martian methane has attracted attention through several reports of its detection over the last 20 years. However, the very existence of this gas has been continuously questioned, in particular, because the observed lifetime should be several orders of magnitude shorter than the 300 years predicted by photochemical models. Although several fast removal processes have been hypothesized to explain the observations, none of them has met a large consensus.It is in this context that the ESA-Roscomos ExoMars Trace Gas Orbiter (TGO) mission started its science operations in April 2018. ACS and NOMAD, two instruments onboard the TGO, have been collecting hundreds of highly sensitive measurements in solar occultation. No methane has been detected so far and an upper limit of 0.02 ppbv has been derived.The implications of this result on the methane problem on Mars will be addressed in this work.This upper limit is a strong constraint on the background level and, in turn, on the potential emission scenarios making the reported methane detections consistent with the TGO results. While several model studies aimed at identifying them, we will here adopt a probabilistic approach to the problem in order to question the plausibility of those detections and estimate the lifetime required to make them plausible from a probabilistic standpoint., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

2. Calibration of the NOMAD-UVIS data

Author

Willame, Yannick, Depiesse, Cédric, Mason, Jonathon P., Thomas, Ian R., Patel, Manish R., Hathi, Brijen, Leese, Mark R., Bolsée, David, Wolff, Michael J., Trompet, Loïc, Vandaele, Ann Carine, Piccialli, Arianna, Aoki, Shohei, Ristic, Bojan, Neefs, Eddy, Beeckman, Bram, Berkenbosch, Sophie, Clairquin, Roland, Mahieux, Arnaud, Pereira, Nuno, Robert, Séverine, Viscardy, Sébastien, Wilquet, Valérie, Daerden, Frank, Lopez-Moreno, José Juan, Bellucci, Giancarlo, Ministerio de Ciencia e Innovación (España), European Commission, and Belgian Science Policy Office

Subjects
Space and Planetary Science, Astronomy and Astrophysics
Abstract

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by- nc-nd/4.0/)., The Ultraviolet and VIsible Spectrometer (UVIS), covering the 200–650 ​nm range, is one of three spectrometers that comprise the NOMAD instrument on the ExoMars 2016 Trace Gas Orbiter (TGO). UVIS can operate in solar occultation, nadir and limb viewing mode and was designed to monitor ozone and aerosols in the Martian atmosphere. Here, we describe the calibration procedure to convert the UVIS raw data into a calibrated data product ready for scientific exploitation. The calibration includes the CCD offset and dark current subtraction, the wavelength assignment, the noise identification and removal, the smearing removal, and the radiance or transmittance conversion. A straylight correction, critical for some parts of the UVIS spectral range, is also applied during the data reduction process, which is described in more detail in two companion papers [Mason et al., 2022; Depiesse et al., In prep] corresponding to two different and independent methods giving consistent results. The solar occultation observations are converted into transmittance and are therefore self-calibrating, while nadir and limb measurements require an absolute radiometric calibration. A comparison with coincident nadir MRO/MARCI measurements is provided as a final validation and generally shows a ±10% agreement on the radiances measured by both instruments. © 2022 The Authors. Published by Elsevier Ltd., The NOMAD experiment is led by the Royal Belgian Institute for Space Aeronomy (IASB-BIRA), assisted by Co-PI teams from Spain (IAA-CSIC), Italy (INAF-IAPS), and the United Kingdom (Open University). This project acknowledges funding by the Belgian Science Policy Office (BELSPO), with the financial and contractual coordination by the ESA Prodex Office (PEA 4000103401, 4000121493), by Spanish Ministry of Science and Innovation (MCIU) and by European funds under grants PGC2018-101836-B-I00 and ESP2017-87143-R (MINECO/FEDER), as well as by UK Space Agency through grants ST/V002295/1, ST/P001262/1, ST/V005332/1 and ST/S00145X/1 and Italian Space Agency through grant 2018-2-HH.0. This work was supported by the Belgian Fonds de la Recherche Scientifique – FNRS under grant number 30442502 (ET_HOME). The IAA/CSIC team acknowledges financial support from the State Agency for Research of the Spanish MCIU through the ‘Center of Excellence Severo Ochoa’ award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709). US investigators were supported by the National Aeronautics and Space Administration. Canadian investigators were supported by the Canadian Space Agency.

Published
2022

3. Water Vapor Vertical Profiles on Mars in Dust Storms Observed by TGO/NOMAD

Author

Aoki, Shohei, Vandaele, Ann Carine, Daerden, Frank, Villanueva, Geronimo L., Liuzzi, Giuliano, Thomas, Ian R., Erwin, Justin T., Trompet, Loïc, Robert, S., Neary, Lori, Viscardy, Sébastien, Clancy, Todd, Smith, Michael D., López-Valverde, Miguel, Hill, B., Ristic, Bojan, Patel, Manish R., Bellucci, Giancarlo, López-Moreno, Jose-Juan, Alonso-Rodrigo, G., Altieri, F., Bauduin, Sophie, and Bolsée, D.

Subjects
Sciences de la terre et du cosmos, Aéronomie, Télédétection, Système solaire, Sciences exactes et naturelles
Abstract

0, info:eu-repo/semantics/published

Published
2019

4. Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter

Author

Vandaele, Ann Carine, Korablev, Oleg, Daerden, Frank, Aoki, Shohei, Thomas, Ian R., ALTIERI, FRANCESCA, López-Valverde, Miguel, Villanueva, Geronimo, Liuzzi, Giuliano, Smith, Michael D., Erwin, Justin T., Trompet, Loïc, Fedorova, Anna A., Montmessin, Franck, Trokhimovskiy, Alexander, Belyaev, Denis A., Ignatiev, Nikolay I., Luginin, Mikhail, Olsen, Kevin S., Baggio, Lucio, Alday, Juan, Bertaux, Jean-Loup, Betsis, Daria, Bolsée, David, Clancy, R. Todd, CLOUTIS, EDWARD, Depiesse, Cédric, Funke, Bernd, Garcia-Comas, Maia, Gérard, Jean-Claude, GIURANNA, MARCO, Gonzalez-Galindo, Francisco, Grigoriev, Alexey V., Ivanov, Yuriy S., Kaminski, Jacek, Karatekin, Ozgur, Lefèvre, Franck, Lewis, Stephen, López-Puertas, Manuel, Mahieux, Arnaud, Maslov, Igor, Mason, Jon, Mumma, Michael J., Neary, Lori, Neefs, Eddy, Patrakeev, Andrey, Patsaev, Dmitry, Ristic, Bojan, Robert, Séverine, Schmidt, Frédéric, Shakun, Alexey, Teanby, Nicholas A., Viscardy, Sébastien, Willame, Yannick, Whiteway, James, Wilquet, Valérie, Wolff, Michael J., BELLUCCI, Giancarlo, Patel, Manish R., López-Moreno, Jose-Juan, Forget, François, Wilson, Colin F., Svedhem, Håkan, Vago, Jorge L., Rodionov, Daniel, NOMAD Science Team, Alonso-Rodrigo, Gustavo, Bauduin, Sophie, Carrozzo, Giacomo, Crismani, Matteo, da Pieve, Fabiana, D'AVERSA, EMILIANO, Etiope, Giuseppe, Fussen, Didier, Geminale, Anna, Gkouvelis, Leo, Holmes, James, Hubert, Benoît, Ignatiev, Nicolay I., Kasaba, Yasumasa, Kass, David, Kleinböhl, Armin, LANCIANO, ORIETTA, Nakagawa, Hiromu, Novak, Robert E., Oliva, Fabrizio, Piccialli, Arianna, Renotte, Etienne, Ritter, Birgit, Schneider, Nick, SINDONI, Giuseppe, Thiemann, Ed, Vander Auwera, Jean, Wilquet, Valerie, WOLKENBERG, PAULINA MARIA, Yelle, Roger, ACS Science Team, Anufreychik, Konstantin, Arnold, Gabriele, Duxbury, Natalia, Fouchet, Thierry, GRASSI, Davide, Guerlet, Sandrine, Hartogh, Paul, Khatuntsev, Igor, Kokonkov, Nikita, Krasnopolsky, Vladimir, Kuzmin, Ruslan, Lacombe, Gaétan, Lellouch, Emmanuel, Määttänen, Anni, Marcq, Emmanuel, Martin-Torres, Javier, Medvedev, Alexander, Millour, Ehouarn, Moshkin, Boris, Quantin-Nataf, Cathy, Rodin, Alexander, Shematovich, Valery, Thomas, Nicolas, Trokhimovsky, Alexander, Vazquez, Luis, Vincendon, Matthieu, Young, Roland, Zasova, Ludmila, Zelenyi, Lev, Zorzano, Maria Paz, Parejo, J, Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Space Research Institute of the Russian Academy of Sciences (IKI), Russian Academy of Sciences [Moscow] (RAS), Main Astronomical Observatory of NAS of Ukraine (MAO), National Academy of Sciences of Ukraine (NASU), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Instituto Universitario de Microgravedad 'Ignacio Da Riva' (IDR), Universidad Politécnica de Madrid (UPM), Spectroscopie de l'atmosphère, Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB), Space Science Institute [Boulder] (SSI), Department of Geography [Winnipeg], University of Winnipeg, NASA Goddard Space Flight Center (GSFC), Laboratoire de Physique Atmosphérique et Planétaire (LPAP), Université de Liège, School of Physical Sciences [Milton Keynes], Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), Institute of Geophysics [Warsaw], Polska Akademia Nauk = Polish Academy of Sciences (PAN), Royal Observatory of Belgium [Brussels] (ROB), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Agenzia Spaziale Italiana (ASI), Graduate School of Information Sciences [Sendai], Tohoku University [Sendai], Advanced Mechanical and Optical Systems SA (AMOS), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], School of Earth Sciences [Bristol], University of Bristol [Bristol], Centre for Research in Earth and Space Science [Toronto] (CRESS), York University [Toronto], Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Department of Physics [Oxford], University of Oxford [Oxford], DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Lomonosov Moscow State University (MSU), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Institute for Astrophysics and Computational Sciences [Washington], Catholic University of America, Department of Computer Science, Electrical and Space Engineering [Luleå], Luleå University of Technology (LUT), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Moscow Institute of Physics and Technology [Moscow] (MIPT), Institute of Astronomy of the Russian Academy of Sciences (INASAN), University of Bern, Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centro de Astrobiologia [Madrid] (CAB), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Université Libre de Bruxelles [Bruxelles] (ULB), The Open University [Milton Keynes] (OU), Polska Akademia Nauk (PAN), Royal Observatory of Belgium [Brussels], IMPEC - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Universidad Complutense de Madrid [Madrid] (UCM), Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Agence Spatiale Européenne = European Space Agency (ESA), University of Oxford, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Ministerio de Ciencia e Innovación (España), European Space Agency, Belgian Science Policy Office, European Commission, UK Space Agency, Agenzia Spaziale Italiana, Ministerio de Ciencia, Innovación y Universidades (España), Fonds de la Recherche Scientifique (Fédération Wallonie-Bruxelles), Roscosmos, Centre National de la Recherche Scientifique (France), and Russian Government

Subjects
Martian, Ice cloud, Multidisciplinary, 010504 meteorology & atmospheric sciences, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Storm, Atmosphere of Mars, Atmospheric sciences, 01 natural sciences, Trace gas, chemistry.chemical_compound, chemistry, 13. Climate action, Dust storm, 0103 physical sciences, Environmental science, Semiheavy water, 010303 astronomy & astrophysics, Water vapor, 0105 earth and related environmental sciences, Sciences exactes et naturelles
Abstract

A publisher correction to this article was published on 17 April 2019, Global dust storms on Mars are rare1,2 but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere3, primarily owing to solar heating of the dust3. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars4. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes5,6, as well as a decrease in the water column at low latitudes7,8. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H2O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals3. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere. © 2019, The Author(s), under exclusive licence to Springer Nature Limited., This project acknowledges funding by the Belgian Science Policy Office (BELSPO), with financial and contractual coordination by the ESA Prodex Office (PEA 4000103401, 4000121493); by the Spanish MICINN through its Plan Nacional and by European funds under grants ESP2015-65064-C2-1-P and ESP2017-87143-R (MINECO/FEDER); by the UK Space Agency through grants ST/R005761/1, ST/P001262/1, ST/R001405/1, ST/S00145X/1, ST/R001367/1, ST/P001572/1 and ST/R001502/1; and the Italian Space Agency through grant 2018-2-HH.0. The IAA/CSIC team acknowledges financial support from the State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severo Ochoa' award for the Instituto de Astrofisica de Andalucia (SEV-2017-0709). This work was supported by the Belgian Fonds de la Recherche Scientifique - FNRS under grant number 30442502 (ET_HOME). The ACS experiment is led by IKI, Space Research Institute in Moscow, assisted by LATMOS in France. The project acknowledges funding by Roscosmos and CNES. The science operations of ACS are funded by Roscosmos and ESA. IKI affiliates acknowledge funding under grant number 14.W03.31.0017 and contract number 0120.0 602993 (0028-2014-0004) of the Russian government.

Published
2019

5. No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations

Author

Korablev, Oleg, Avandaele, Ann Carine, Montmessin, Franck, Fedorova, Anna A., Trokhimovskiy, Alexander, Forget, François, Lefèvre, Franck, Daerden, Frank, Thomas, Ian R., Trompet, Loïc, Erwin, Justin T., Kasaba, Yasumasa, Kass, David, Khatuntsev, Igor, Kleinböhl, Armin, Kokonkov, Nikita, Krasnopolsky, Vladimir, Kuzmin, Ruslan, Lacombe, Gaétan, LANCIANO, ORIETTA, Lellouch, Emmanuel, Oliva, Fabrizio, Lewis, Stephen, Luginin, Mikhail, Liuzzi, Giuliano, López-Puertas, Manuel, López-Valverde, Miguel, Määttänen, Anni, Mahieux, Arnaud, Marcq, Emmanuel, Martin-Torres, Javier, Maslov, Igor, Patsaev, Dmitry, Medvedev, Alexander, Millour, Ehouarn, Moshkin, Boris, Mumma, Michael J., Nakagawa, Hiromu, Novak, Robert E., Piccialli, Arianna, Quantin-Nataf, Cathy, Renotte, Etienne, Ritter, Birgit, Rodin, Alexander, Schmidt, Frédéric, Schneider, Nick, Shematovich, Valery, Aoki, Shohei, Smith, Michael D., Teanby, Nicholas A., Thiemann, Ed, Thomas, Nicolas, Vander Auwera, Jean, Vazquez, Luis, Villanueva, Geronimo, Vincendon, Matthieu, Whiteway, James, Wilquet, Valérie, Robert, Séverine, Wolff, Michael J., WOLKENBERG, PAULINA MARIA, Yelle, Roger, Young, Roland, Zasova, Ludmila, Zorzano, Maria Paz, Neary, Lori, Viscardy, Sébastien, Grigoriev, Alexey V., Ignatiev, Nikolay I., Shakun, Alexey, Patrakeev, Andrey, Belyaev, Denis A., Bertaux, Jean-Loup, Olsen, Kevin S., Baggio, Lucio, Alday, Juan, Ivanov, Yuriy S., Ristic, Bojan, Mason, Jon, Willame, Yannick, Depiesse, Cédric, Hetey, Laszlo, Berkenbosch, Sophie, Clairquin, Roland, Queirolo, Claudio, Beeckman, Bram, Neefs, Eddy, Patel, Manish R., BELLUCCI, Giancarlo, López-Moreno, Jose-Juan, Wilson, Colin F., Etiope, Giuseppe, Zelenyi, Lev, Svedhem, Håkan, Vago, Jorge L., ACS Science Team, NOMAD Science Team, Alonso-Rodrigo, Gustavo, ALTIERI, FRANCESCA, Anufreychik, Konstantin, Arnold, Gabriele, Bauduin, Sophie, Bolsée, David, CARROZZO, FILIPPO GIACOMO, Clancy, R. Todd, CLOUTIS, EDWARD, Crismani, Matteo, da Pieve, Fabiana, D'AVERSA, EMILIANO, Duxbury, Natalia, Encrenaz, Therese, Fouchet, Thierry, Funke, Bernd, Fussen, Didier, Garcia-Comas, Maia, Gérard, Jean-Claude, GIURANNA, MARCO, Gkouvelis, Leo, Gonzalez-Galindo, Francisco, GRASSI, Davide, Guerlet, Sandrine, Hartogh, Paul, Holmes, James, Hubert, Benoît, Kaminski, Jacek, Karatekin, Ozgur, Space Research Institute of the Russian Academy of Sciences (IKI), Russian Academy of Sciences [Moscow] (RAS), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Department of Physics [Oxford], University of Oxford [Oxford], Main Astronomical Observatory of NAS of Ukraine (MAO), National Academy of Sciences of Ukraine (NASU), School of Physical Sciences [Milton Keynes], Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Faculty of Environmental Science and Engineering [Cluj-Napoca], Babes-Bolyai University [Cluj-Napoca] (UBB), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Instituto Universitario de Microgravedad 'Ignacio Da Riva' (IDR), Universidad Politécnica de Madrid (UPM), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Spectroscopie de l'atmosphère, Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB), Space Science Institute [Boulder] (SSI), Department of Geography [Winnipeg], University of Winnipeg, NASA Goddard Space Flight Center (GSFC), Lomonosov Moscow State University (MSU), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Atmosphérique et Planétaire (LPAP), Université de Liège, Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Institute of Geophysics [Warsaw], Polska Akademia Nauk = Polish Academy of Sciences (PAN), Royal Observatory of Belgium [Brussels] (ROB), Graduate School of Information Sciences [Sendai], Tohoku University [Sendai], Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Institute for Astrophysics and Computational Sciences [Washington], Catholic University of America, Agenzia Spaziale Italiana (ASI), Department of Computer Science, Electrical and Space Engineering [Luleå], Luleå University of Technology (LUT), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Advanced Mechanical and Optical Systems SA (AMOS), Moscow Institute of Physics and Technology [Moscow] (MIPT), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Institute of Astronomy of the Russian Academy of Sciences (INASAN), School of Earth Sciences [Bristol], University of Bristol [Bristol], University of Bern, Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre for Research in Earth and Space Science [Toronto] (CRESS), York University [Toronto], Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Belgian Science Policy Office, Ministerio de Ciencia e Innovación (España), European Commission, UK Space Agency, Centre National de la Recherche Scientifique (France), Fonds de la Recherche Scientifique (Fédération Wallonie-Bruxelles), Roscosmos, Russian Government, Agenzia Spaziale Italiana, European Space Agency, IMPEC - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), The Open University [Milton Keynes] (OU), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Université Libre de Bruxelles [Bruxelles] (ULB), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Polska Akademia Nauk (PAN), Royal Observatory of Belgium [Brussels], Universidad Complutense de Madrid [Madrid] (UCM), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), University of Oxford, Agence Spatiale Européenne = European Space Agency (ESA), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES)

Subjects
Martian, Multidisciplinary, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010504 meteorology & atmospheric sciences, Chemistry, Atmosphere of Mars, Mars Exploration Program, 01 natural sciences, 7. Clean energy, Methane, Trace gas, law.invention, Astrobiology, Atmosphere, Orbiter, chemistry.chemical_compound, 13. Climate action, law, Atmospheric chemistry, 0103 physical sciences, 010303 astronomy & astrophysics, Sciences exactes et naturelles, 0105 earth and related environmental sciences
Abstract

A publisher correction to this article was published on 17 April 2019, The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today1. A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations2–5. These measurements, however, are difficult to reconcile with our current understanding of the chemistry and physics of the Martian atmosphere6,7, which—given methane’s lifetime of several centuries—predicts an even, well mixed distribution of methane1,6,8. Here we report highly sensitive measurements of the atmosphere of Mars in an attempt to detect methane, using the ACS and NOMAD instruments onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter from April to August 2018. We did not detect any methane over a range of latitudes in both hemispheres, obtaining an upper limit for methane of about 0.05 parts per billion by volume, which is 10 to 100 times lower than previously reported positive detections2,4. We suggest that reconciliation between the present findings and the background methane concentrations found in the Gale crater4 would require an unknown process that can rapidly remove or sequester methane from the lower atmosphere before it spreads globally. © 2019, The Author(s), under exclusive licence to Springer Nature Limited., ExoMars is the space mission of ESA and Roscosmos. The ACS experiment is led by IKI, the Space Research Institute in Moscow, assisted by LATMOS in France. The project acknowledges funding by Roscosmos and CNES. The science operations of ACS are funded by Roscosmos and ESA. IKI affiliates acknowledge funding under grant number 14.W03.31.0017 and contract number 0120.0 602993 (0028-2014-0004) of the Russian government. The NOMAD experiment is led by the Royal Belgian Institute for Space Aeronomy (BIRA-IASB), assisted by co-PI teams from Spain (IAA-CSIC), Italy (INAF-IAPS), and the UK (Open University). This project acknowledges funding by the Belgian Science Policy Office (BELSPO), with the financial and contractual coordination of the ESA Prodex Office (PEA 4000103401 and PEA 4000121493), by Spanish MICINN through its Plan Nacional and by European funds under grants ESP2015-65064-C2-1-P and ESP2017-87143-R (MINECO/FEDER), as well as by the UK Space Agency through grants ST/R005761/1, ST/P001262/1, ST/R001405/1, ST/S00145X/1, ST/R001367/1, ST/P001572/1 and ST/R001502/1, and the Italian Space Agency through grant 2018-2-HH.0. This work was supported by the Belgian Fonds de la Recherche Scientifique-FNRS under grant number 30442502 (ET_HOME).

Published
2019

6. Retrievals of Ozone at the Terminator of Mars from Spicam/mex Solar Occultations

Author

Piccialli, Arianna, Vandaele, Ann Carine, Robert, Séverine, Daerden, F., Viscardy, Sébastien, Trompet, Loic, Neary, Lori, Aoki, Shohei, Willame, Yannick, Wilquet, Valérie, Lefèvre, Franck, Määttänen, Anni, Montmessin, Franck, Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Fonds National de la Recherche Scientifique [Bruxelles] (FNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Cardon, Catherine, and Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2018

7. NOMAD, an integrated suite of three spectrometers for the ExoMars trace gas mission: Technical description, science objectivs and expected performance

Author

Vandaele, Ann Carine, Lopez-Moreno, J.-J., Patel, M.R., Bellucci, G., Daerden, F., Ristic, B., Robert, Séverine, Thomas, I.R., Wilquet, Valérie, Allen, M., Alonso-Rodrigo, G., Altieri, F., Aoki, S, Bolsée, D., Clancy, T., Cloutis, E., Depiesse, Cédric, Drummond, Rachel, Fedorova, A., Formisano, V., Funke, Bernd, Gonzalez-Galindo, F., Geminale, A., Gérard, J.-C., Giuranna, M., Hetey, L., Ignatiev, N., Kaminski, J., Karatekin, Ozgur, Kasaba, Y., Leese, M., Lefèvre, F., Lewis, S. R., Lopez-Puertas, Manuel, Lopez-Valverde, M.A., Mahieux, Arnaud, Mason, James, McConnell, John, Mumma, M., Neary, L., Neefs, Eddy, Renotte, E., Gómez-Rodriguez, Julio, Sindoni, G., Smith, M., Stiepen, A., Trokhimovsky, A., Vander Auwera, Jean, Villanueva, G., Viscardy, Sébastien, Whiteway, J.A., Willame, Yannick, Wolff, M., and NOMAD, Team

Subjects
Spectroscopie [électromagnétisme, optique, acoustique], Chimie, Physique atomique et moléculaire
Abstract

info:eu-repo/semantics/published

Published
2018

8. A test case: new retrievals of ozone at the terminator on Mars

Author

Piccialli, Arianna, Vandaele, Ann Carine, Robert, Séverine, Daerden, Frank, Viscardy, Sébastien, Neary, Lori, Aoki, Shohei, Wilquet, Valérie, Lefèvre, Franck, Määttänen, Anni, Montmessin, Franck, Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Fonds National de la Recherche Scientifique [Bruxelles] (FNRS), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Abstract

International audience; ASIMUT, the BIRA-IASB radiative transfer code, was modified in order to take into account the changes in the atmospheric composition and structure across the martian day/night terminator.Here, we will discuss the impact of this implementation on the retrievals of ozone profiles derived from SPICAM solar occultations in the ultraviolet.

Published
2017

9. Viscosity and Microscopic Chaos: The Helfand-moment Approach (Viscosité et Chaos Microscopique: Approche par le Moment de Helfand)

Author

Viscardy, Sébastien, Nicolis, Grégoire, Turner, John W., Mareschal, Michel, Dorfman, J. Robert, Buess-Herman, Claudine, and Gaspard, Pierre

Subjects
histoire des sciences / history of science, mécanique statistique de non-équilib, dynamique moléculaire / molecular dynamics, processus de transport / transport processes, théorie des systèmes dynamiques / dy, viscosité / viscosity, chaos microscopique / microscopic chaos
Abstract

Depuis les premiers développements de la physique statistique réalisés au 19ème siècle, nombreux ont été les travaux dédiés à la relation entre les processus macroscopiques em>irréversibles(tels que les phénomènes de transport) et les propriétés de la dynamique réversible des atomes et des molécules. Depuis deux décennies, l'hypothèse du chaos microscopique nous en apporte une plus grande compréhension. Dans cette thèse, nous nous intéressons plus particulièrement aux propriétés de viscosité. Dans ce travail, nous considérons des systèmes périodiques de particules en interaction. Nous proposons une nouvelle méthode de calcul de la viscosité valable pour tous systèmes périodiques, quel que soit le potentiel d'interaction considéré. Cette méthode est basée sur la formule dérivée par Helfand exprimant la viscosité en fonction de la variance du moment de Helfand croissant linéairement dans le temps. Dans les années nonante, il a été démontré qu'un système composé de seulement deux particules présente déjà de la viscosité. Les deux disques durs interagissent en collisions élastiques dans un domaine carré ou hexagonal avec des conditions aux bords périodiques. Nous appliquons notre méthode de calcul des propriétés de viscosité dans les deux réseaux. Nous donnons également une explication qualitative des résultats obtenus. L'étude de la relation entre les propriétés de viscosité et les grandeurs du chaos microscopique représente l'une des principales tâches de cette thèse. Dans ce contexte, le formalisme du taux d'échappement joue un rôle majeur. Ce formalisme établit une relation directe entre cette grandeur et la viscosité. Nous étudions numériquement cette relation et la comparaison avec les résultats obtenus par notre méthode sont excellents. D'autre part, le formalisme du taux d'échappement suppose l'existence d'un répulseur fractal. Après avoir mis en évidence son existence, nous appliquons le formalisme proposant une formule exprimant la viscosité en termes de l'exposant de Lyapunov du système (mesurant le caractère chaotique de la dynamique)et de la dimension fractale du répulseur. L'étude numérique de cette relation dans le modèle à deux disques durs est réalisée avec succès et sont en excellent accord avec les relations obtenus précédemment. Enfin, nous nous penchons sur les systèmes composés de N disques durs ou sphères dures. Après une étude de l'équation d'état et des propriétés chaotiques, nous avons exploré les propriétés de viscosité dans ces systèmes. Les données numériques obtenues sont en très bon accord avec les prévisions théoriques d'Enskog. D'autre part, nous avons utilisé notre méthode de calcul de la viscosité dans des systèmes de Lennard-Jones. De plus, nous avons proposé une méthode analogue pour le calcul numérique de la conduction thermique. Nos résultats sont en très bon accord avec ceux obtenus par la méthode de Green-Kubo. In this thesis, we first devote a section on the history of the concept of irreversibility; of the hydrodynamics, branch of physics in which the viscosity appears; of the kinetic theory of gases establishing relationships between the microscopic dynamics and macroscopic processes like viscosity; and, finally, the interest brought in statistical mechanics of irreversible processes by the theory of chaos, more precisely, the microscopic chaos. We propose a method based on the Helfand moment in order to calculate the viscosity properties in systems of particles with periodic boundary conditions. We apply this method to the simplest system in which viscosity already exists: the two-hard-disk model. The escape-rate formalism, establishing a direct relation between chaotic quantities of the microscopic dynamics (e.g. Lyapunov exponents, fractal dimensions, etc.), is applied in this system. The results are in excellent agreement with those obtained by our Helfand-moment method. We extend the calculation of the viscosity properties to systems with more than two hard balls. Finally, we compute viscosity as well as thermal conductivity thanks to our own method also based on the Helfand moment., Doctorat en sciences, Spécialisation physique, info:eu-repo/semantics/published

Published
2005

10. Viscosité et chaos mircroscopique: approche par le moment de Helfand

Author

Viscardy, Sébastien, Gaspard, Pierre, Buess Herman, Claudine, Nicolis, Grégoire, Turner, John, Mareschal, Michel, and Dorfman, J. Robert

Subjects
Théorie des systèmes, Viscosity, dynamique moléculaire / molecular dynamics, Transport, Théorie du, chaos microscopique / microscopic chaos, Molecular dynamics, histoire des sciences / history of science, Transport theory, Viscosité, mécanique statistique de non-équilib, Dynamique moléculaire, processus de transport / transport processes, Chimie, théorie des systèmes dynamiques / dy, viscosité / viscosity, System theory, Sciences exactes et naturelles
Abstract

Depuis les premiers développements de la physique statistique réalisés au 19ème siècle, nombreux ont été les travaux dédiés à la relation entre les processus macroscopiques em>irréversibles(tels que les phénomènes de transport) et les propriétés de la dynamique réversible des atomes et des molécules. Depuis deux décennies, l'hypothèse du chaos microscopique nous en apporte une plus grande compréhension. Dans cette thèse, nous nous intéressons plus particulièrement aux propriétés de viscosité. Dans ce travail, nous considérons des systèmes périodiques de particules en interaction. Nous proposons une nouvelle méthode de calcul de la viscosité valable pour tous systèmes périodiques, quel que soit le potentiel d'interaction considéré. Cette méthode est basée sur la formule dérivée par Helfand exprimant la viscosité en fonction de la variance du moment de Helfand croissant linéairement dans le temps.Dans les années nonante, il a été démontré qu'un système composé de seulement deux particules présente déjà de la viscosité. Les deux disques durs interagissent en collisions élastiques dans un domaine carré ou hexagonal avec des conditions aux bords périodiques. Nous appliquons notre méthode de calcul des propriétés de viscosité dans les deux réseaux. Nous donnons également une explication qualitative des résultats obtenus. L'étude de la relation entre les propriétés de viscosité et les grandeurs du chaos microscopique représente l'une des principales tâches de cette thèse. Dans ce contexte, le formalisme du taux d'échappement joue un rôle majeur. Ce formalisme établit une relation directe entre cette grandeur et la viscosité. Nous étudions numériquement cette relation et la comparaison avec les résultats obtenus par notre méthode sont excellents. D'autre part, le formalisme du taux d'échappement suppose l'existence d'un répulseur fractal. Après avoir mis en évidence son existence, nous appliquons le formalisme proposant une formule exprimant la viscosité en termes de l'exposant de Lyapunov du système (mesurant le caractère chaotique de la dynamique)et de la dimension fractale du répulseur. L'étude numérique de cette relation dans le modèle à deux disques durs est réalisée avec succès et sont en excellent accord avec les relations obtenus précédemment. Enfin, nous nous penchons sur les systèmes composés de N disques durs ou sphères dures. Après une étude de l'équation d'état et des propriétés chaotiques, nous avons exploré les propriétés de viscosité dans ces systèmes. Les données numériques obtenues sont en très bon accord avec les prévisions théoriques d'Enskog. D'autre part, nous avons utilisé notre méthode de calcul de la viscosité dans des systèmes de Lennard-Jones. De plus, nous avons proposé une méthode analogue pour le calcul numérique de la conduction thermique. Nos résultats sont en très bon accord avec ceux obtenus par la méthode de Green-Kubo.In this thesis, we first devote a section on the history of the concept of irreversibility; of the hydrodynamics, branch of physics in which the viscosity appears; of the kinetic theory of gases establishing relationships between the microscopic dynamics and macroscopic processes like viscosity; and, finally, the interest brought in statistical mechanics of irreversible processes by the theory of chaos, more precisely, the microscopic chaos. We propose a method based on the Helfand moment in order to calculate the viscosity properties in systems of particles with periodic boundary conditions. We apply this method to the simplest system in which viscosity already exists: the two-hard-disk model. The escape-rate formalism, establishing a direct relation between chaotic quantities of the microscopic dynamics (e.g. Lyapunov exponents, fractal dimensions, etc.), is applied in this system. The results are in excellent agreement with those obtained by our Helfand-moment method. We extend the calculation of the viscosity properties to systems with more than two hard balls. Finally, we compute viscosity as well as thermal conductivity thanks to our own method also based on the Helfand moment., Doctorat en sciences, Spécialisation physique, info:eu-repo/semantics/nonPublished

Published
2005

11. Methane on Mars and Habitability: Challenges and Responses

Author

Yung, Yuk L., Chen, Pin, Nealson, Kenneth H., Atreya, Sushil, Beckett, Patrick, Blank, Jennifer, Ehlmann, Bethany, Eiler, John, Etiope, Giuseppe, Ferry, James G., Forget, Francois, Gao, Peter, Hu, Renyu, Kleinböhl, Armin, Klusman, Ronald, Lefèvre, Franck, Miller, Charles, Mischna, Michael, Mumma, Michael, Newman, Sally, Oehler, Dorothy, Okumura, Mitchio, Oremland, Ronald, Orphan, Victoria, Popa, Radu, Russell, Michael, Shen, Linhan, Sherwood Lollar, Barbara, Stamenković, Vlada, Staehle, Robert, Stolper, Daniel, Templeton, Alex, Vandaele, Ann C., Viscardy, Sébastien, Webster, Chris, Wennberg, Paul O., Wong, Michael, and Worden, John

Subjects
13. Climate action, Mars, methane, 7. Clean energy
Abstract

Recent measurements of methane (CH_4) by the Mars Science Laboratory (MSL) now confront us with robust data that demand interpretation. The baseline level of CH_4 (~1 ppbv, parts per billion by volume) requires a minimum production source of 1.7 × 10^7 mol year^(-1), while the pulses of CH_4 (~10 ppbv) require a source orders of magnitude larger (~5 × 10^9 mol year^(-1) if originating from a point source). What does this CH_4 represent in terms of interior geochemical processes, or is Martian CH_4 a biosignature? Discerning how CH_4 generation occurs on Mars may shed light on the potential habitability of Mars. There is no evidence of life on the surface of Mars today, but microbes might reside beneath the surface. In this case, the carbon flux represented by CH_4 might serve as a link between a putative subterranean biosphere on Mars and what we can measure above the surface. Alternatively, if there is no life, CH_4 records modern activity. We ask the fundamental question: how active is Mars, geochemically and/or biologically? In this report, we examine geological, geochemical, and biogeochemical processes related to our overarching question. The Martian atmosphere and surface is an overwhelmingly oxidizing environment, and life requires pairing of electron donors and electron acceptors, i.e., redox gradients, as an essential source of energy. Therefore, a fundamental and critical question regarding the possibility of life on Mars is, "Where can we find redox gradients as energy sources for life on Mars?" Hence, regardless of the pathway that generates CH_4 on Mars, the presence of CH_4, a reduced species in an oxidant-rich environment, suggests the possibility of redox gradients supporting life and habitability on Mars. Recent missions such as ExoMars Trace Gas Orbiter (TGO) may provide mapping of the global distribution of CH_4. To discriminate between abiotic and biotic sources of CH_4 on Mars, future studies should use a series of diagnostic geochemical analyses, preferably performed below the ground or at the ground/atmosphere interface, including measurements of CH_4 isotopes, methane/ethane ratios, H_2 gas concentration, and species such as acetic acid. Advances in the fields of Mars exploration and instrumentation will be driven, augmented, and supported by an improved understanding of atmospheric chemistry and dynamics, deep-subsurface biogeochemistry, astrobiology, planetary geology, and geophysics. Future Mars exploration programs will have to expand the integration of complementary areas of expertise to generate synergistic and innovative ideas to realize breakthroughs in advancing our understanding of the potential of life and habitable conditions having existed on Mars. In this spirit, we conducted a set of interdisciplinary workshops. From this series has emerged a vision of technological, theoretical, and methodological innovations to explore the Martian subsurface and to enhance spatial tracking of key volatiles, such as CH_4.

12. Martian dust storm impact on atmospheric H₂O and D/H observed by ExoMars Trace Gas Orbiter

Author

Vandaele, Ann Carine, Korablev, Oleg, Daerden, Frank, Aoki, Shohei, Thomas, Ian R., Altieri, Francesca, López-Valverde, Miguel, Villanueva, Geronimo, Liuzzi, Giuliano, Smith, Michael D., Erwin, Justin T., Trompet, Loïc, Fedorova, Anna A., Montmessin, Franck, Trokhimovskiy, Alexander, Belyaev, Denis A., Ignatiev, Nikolay I., Luginin, Mikhail, Olsen, Kevin S., Baggio, Lucio, Alday, Juan, Bertaux, Jean-Loup, Betsis, Daria, Bolsée, David, Clancy, R. Todd, Cloutis, Edward, Depiesse, Cédric, Funke, Bernd, Garcia-Comas, Maia, Gérard, Jean-Claude, Giuranna, Marco, Gonzalez-Galindo, Francisco, Grigoriev, Alexey V., Ivanov, Yuriy S., Kaminski, Jacek, Karatekin, Ozgur, Lefèvre, Franck, Lewis, Stephen, López-Puertas, Manuel, Mahieux, Arnaud, Maslov, Igor, Mason, Jon, Mumma, Michael J., Neary, Lori, Neefs, Eddy, Patrakeev, Andrey, Patsaev, Dmitry, Ristic, Bojan, Robert, Séverine, Schmidt, Frédéric, Shakun, Alexey, Teanby, Nicholas A., Viscardy, Sébastien, Willame, Yannick, Whiteway, James, Wilquet, Valérie, Wolff, Michael J., Bellucci, Giancarlo, Patel, Manish R., López-Moreno, Jose-Juan, Forget, François, Wilson, Colin F., Svedhem, Håkan, Vago, Jorge L., and Rodionov, Daniel

Subjects
13. Climate action, 520 Astronomy, 620 Engineering
Abstract

Global dust storms on Mars are rare but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere, primarily owing to solar heating of the dust. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes, as well as a decrease in the water column at low latitudes. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H₂O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H₂O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals. The observed changes in H₂O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere.

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