1. Background levels of methane in Mars’ atmosphere show strong seasonal variations
- Author
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María Paz Zorzano, Mark T. Lemmon, Lance E. Christensen, Daniel P. Glavin, Álvaro Vicente-Retortillo, Christopher P. McKay, Jennifer L. Eigenbrode, Jorge Pla-Garcia, Brad Sutter, Christopher R. Webster, Henrik Kahanpää, Daniel Viúdez-Moreiras, John C. Pearson, Melissa G. Trainer, Christina L. Smith, Rafael Navarro-González, P. Douglas Archer, Paul R. Mahaffy, Michael H. Wong, Andrew Steele, Patrice Coll, Ashwin R. Vasavada, Christopher H. House, Donald M. Hassler, Richard W. Zurek, G. Flesch, Pierre-Yves Meslin, Javier Gómez-Elvira, John E. Moores, Caroline Freissinet, Susanne P. Schwenzer, German Martinez, Scot Rafkin, Alexander A. Pavlov, Stanley P. Sander, Ari-Matti Harri, Charles Malespin, Sushil K. Atreya, Joy A. Crisp, Didier Keymeulen, Raina V. Gough, Maria Genzer, Javier Martin-Torres, Michael D. Smith, Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, NASA Goddard Space Flight Center (GSFC), Department of Climate and Space Sciences and Engineering (CLaSP), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Department of Earth and Space Science and Engineering [York University - Toronto] (ESSE), York University [Toronto], NASA Ames Research Center (ARC), Department of Computer Science, Electrical and Space Engineering [Luleå], Luleå University of Technology (LUT), Instituto Andaluz de Ciencias de la Tierra (IACT), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Universidad de Granada (UGR), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Geophysical Laboratory [Carnegie Institution], Carnegie Institution for Science [Washington], Jacobs Technology ESCG, Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), 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), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry and Biochemistry [Boulder], University of Colorado [Boulder], Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado [Boulder]-National Oceanic and Atmospheric Administration (NOAA), Department of Geosciences [PennState], College of Earth and Mineral Sciences, Pennsylvania State University (Penn State), Penn State System-Penn State System-Pennsylvania State University (Penn State), Penn State System-Penn State System, The Open University [Milton Keynes] (OU), School of Environment, Earth and Ecosystem Sciences [Milton Keynes], Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), Instituto de Ciencias Nucleares [Mexico], Universidad Nacional Autónoma de México (UNAM), Space Science Institute [Boulder] (SSI), Department of Space Studies [Boulder], Southwest Research Institute [Boulder] (SwRI), Finnish Meteorological Institute (FMI), Department of Atmospheric Sciences [College Station], Texas A&M University [College Station], NASA-California Institute of Technology (CALTECH), Carnegie Institution for Science, 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), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), NASA Jet Propulsion Laboratory, Consejo Nacional de Ciencia y Tecnología (México), Canadian Space Agency, UK Space Agency, Ministerio de Economía y Competitividad (España), Universidad de Granada (UGR)-Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), IMPEC - LATMOS, Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Universidad de Granada = University of Granada (UGR), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
- Subjects
Multidisciplinary ,010504 meteorology & atmospheric sciences ,Spectrometer ,Parts-per notation ,Atmosphere of Mars ,Seasonality ,Surface pressure ,medicine.disease ,Atmospheric sciences ,01 natural sciences ,[SDE.ES]Environmental Sciences/Environmental and Society ,Methane ,chemistry.chemical_compound ,Forum Articles ,chemistry ,Volume (thermodynamics) ,13. Climate action ,Martian surface ,0103 physical sciences ,medicine ,Environmental science ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences - Abstract
Variable levels of methane in the martian atmosphere have eluded explanation partly because the measurements are not repeatable in time or location.We report in situ measurements at Gale crater made over a 5-year period by the Tunable Laser Spectrometer on the Curiosity rover.The background levels of methane have a mean value 0.41 ± 0.16 parts per billion by volume (ppbv) (95% confidence interval) and exhibit a strong, repeatable seasonal variation (0.24 to 0.65 ppbv).This variation is greater than that predicted from either ultraviolet degradation of impact-delivered organics on the surface or from the annual surface pressure cycle.The large seasonal variation in the background and occurrences of higher temporary spikes (∼7 ppbv) are consistent with small localized sources of methane released from martian surface or subsurface reservoirs., The authors thank the reviewers for constructive comments that greatly improved the manuscript. The research described here was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). Funding: Funding from NASA’s Planetary Science Division is acknowledged by authors C.R.W., P.R.M., S.K.A., G.J.F., C.M., C.P.M., M.H.W., M.G.T., A.S., D.A., C.H.H., R.V.G., A.P., J.L.E., D.P.G., J.C.P., D.K., L.E.C., J.P.-G., S.C.R.R., M.D.S., D.M.H., M.L., J.C., R.W.Z., and A.R.V. R.N.-G. acknowledges funding from the National Autonomous University of Mexico and Consejo Nacional de Ciencia y Tecnología. J.E.M. and C.L.S. acknowledge funding from the Canadian Space Agency MSL participating scientist program. S.P.Sc. acknowledges funding from the UK Space Agency. A.-M.H. acknowledges funding from the Finnish Academy under grant 310509. J.P.-G. acknowledges funding from the Spanish Ministry of Economy and Competitiveness under contract ESP2016-79612-C3-1-R. Author contributions: C.R.W. and P.R.M. performed TLS-SAM instrument design, build, and testing (IDBT); surface operations (SO); test-bed activities (TBA); data analysis (DA); data correlations (DC); and science interpretation (SI). G.J.F. and C.M. performed IDBT, SO, TBA, and DA. S.K.A., J.E.M., C.P.M., C.L.S., A.S., D.A., B.S., P.J.C., C.F., P.-Y.M., R.V.G., C.H.H., A.P., J.L.E., D.P.G., S.P.Sa., and R.W.Z. performed SI. J.C. and A.R.V. performed SO. J.C.P., D.K., and L.E.C. performed IDBT. G.M., J.M.-T., J.G.-E., M.-P.Z., M.G.T., S.P.Sc., R.N.-G., A.V.-R., H.K., D.V.-M., M.D.S., A.-M.H., M.G., D.M.H., and M.L. performed DC. J.P.-G. and S.C.R.R. performed DC and SI. Competing interests: No potential conflicts of interest exist for any of the listed authors. Data and materials availability: The data described in this paper are publicly available from NASA’s Planetary Data System (PDS) under an arrangement with the Mars Science Laboratory (MSL) project at http://pds-geosciences.wustl.edu/missions/msl/sam. htm, under the run numbers given in table S2.
- Published
- 2018