Atmosphere; Infrared spectroscopy; Mars; Methane; Astronomy and Astrophysics; Space and Planetary Science
Abstract :
[en] Methane (CH4) on Mars has attracted a great deal of attention since it was first detected in January 2003. As methane is considered a potential marker for past/present biological or geological activity, any possible detection would require evidence with strong statistical significance. Ethane (C2H6) and ethylene (C2H4) are also relevant chemical species as their shorter lifetimes in the Martian atmosphere make them excellent tracers for recent and ongoing releases. If detected, a CH4/C2Hn ratio could aid in constraining the potential source of organic production. Here we present the results of an extensive search for hydrocarbons in the Martian atmosphere in 240,000 solar occultation measurements performed by the ExoMars Trace Gas Orbiter/NOMAD instrument from April 2018 to April 2019. The observations are global, covering all longitudes and latitudes from 85°N to 85°S, and sampled from 6 to 100 km altitude with a typical vertical resolution of 2 km. There were no statistically significant detections of organics and new stringent upper limits for global ethane and ethylene were set at 0.1 ppbv and 0.7 ppbv, respectively. No global background level of methane was observed, obtaining an upper limit of 0.06 ppbv, in agreement with early results from ExoMars (Korablev et al., 2019). Dedicated searches for localized plumes at more than 2000 locations provided no positive detections, implying that if methane were released in strong and rapid events, the process would have to be sporadic.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Knutsen, Elise W.; NASA Goddard Space Flight Center, United States ; Department of Physics, American University, United States
Villanueva, Geronimo L.; NASA Goddard Space Flight Center, United States
Liuzzi, Giuliano; NASA Goddard Space Flight Center, United States ; Department of Physics, American University, United States
Crismani, Matteo M.J.; NPP/USRA, Goddard Space Flight Center, United States ; California State University, San Bernardino, United States
Mumma, Michael J.; NASA Goddard Space Flight Center, United States
Smith, Michael D.; NASA Goddard Space Flight Center, United States
Vandaele, Ann Carine; Royal Belgian Institute for Space Aeronomy, Belgium
Aoki, Shohei ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP) ; Royal Belgian Institute for Space Aeronomy, Belgium
Thomas, Ian R.; Royal Belgian Institute for Space Aeronomy, Belgium
Daerden, Frank; Royal Belgian Institute for Space Aeronomy, Belgium
Viscardy, Sébastien; Royal Belgian Institute for Space Aeronomy, Belgium
Erwin, Justin T.; Royal Belgian Institute for Space Aeronomy, Belgium
Trompet, Loic; Royal Belgian Institute for Space Aeronomy, Belgium
Neary, Lori; Royal Belgian Institute for Space Aeronomy, Belgium
Ristic, Bojan; Royal Belgian Institute for Space Aeronomy, Belgium
Lopez-Valverde, Miguel Angel; Instituto de Astrofísica de Andalucía, IAA/CSIC, Spain
Lopez-Moreno, Jose Juan; Instituto de Astrofísica de Andalucía, IAA/CSIC, Spain
Patel, Manish R.; School of Physical Sciences, The Open University, Milton Keynes, United Kingdom ; Space Science and Technology Department, Science and Technology Facilities Council, Rutherford
Karatekin, Ozgur; Royal Observatory of Belgium, Belgium
Bellucci, Giancarlo; Istituto di Astrofisica e Planetologia Spaziali, Italy
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/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). Canadian investigators were supported by the Canadian Space Agency . This work was supported by NASA's Mars Program Office under WBS 604796 , “Participation in the TGO/NOMAD Investigation of Trace Gases on Mars”. MC is supported by the NASA Postdoctoral Program at the NASA Goddard Space Flight Center , administered by Universities Space Research Association (USRA) under contract with NASA. S. A. is “Chargé de Recherches” at the F.R.S.-FNRS. We would also like to thank Dr. Sara Faggi for valuable advice, expertise and continuous support during this study.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/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 Astrof?sica de Andaluc?a (SEV-2017-0709). Canadian investigators were supported by the Canadian Space Agency. This work was supported by NASA's Mars Program Office under WBS 604796, ?Participation in the TGO/NOMAD Investigation of Trace Gases on Mars?. MC is supported by the NASA Postdoctoral Program at the NASA Goddard Space Flight Center, administered by Universities Space Research Association (USRA) under contract with NASA. S. A. is ?Charg? de Recherches? at the F.R.S.-FNRS. We would also like to thank Dr. Sara Faggi for valuable advice, expertise and continuous support during this study.
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