4932 20200616051155.0 10.1038/s41586-019-1096-4 DOI SCART-2020-0129 Korablev, Oleg No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations 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 concentrations2,3,4,5. 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. NO Avandaele, Ann Carine Montmessin, Franck Fedorova, Anna A. Trokhimovskiy, Alexander Forget, Francois Lefevre, Franck Daerden, Frank Thomas, Ian R. Trompet, Lo√Øc Erwin, Justin T. Aoki, Shohei Robert, S√©verine Neary, Lori Viscardy, S√©bastien 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, Cedric Hetey, Laszlo Berkenbosch, Sophie Clairquin, Roland Queirolo, Claudio Beeckman, Bram Neefs, Eddy Patel, Manish R. Bellucci, Giancarlo Lopez-Moreno, Jose-Juan Wilson, Colin F. Etiope, Giuseppe Zelenyi, Lev Svedhem, H√•kan Vago, Jorge L. Alonso-Rodrigo, Gustavo Altieri, Francesca Anufreychik, Konstantin Arnold, Gabriele Bauduin, Sophie Bolsee, David Carrozzo, 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 Gerard, Jean-Claude Giuranna, Marco Gkouvelis, Leo Gonzalez-Galindo, Francisco Grassi, Davide Guerlet, Sandrine Hartogh, Paul Holmes, James Hubert, Beno√Æt Kaminski, Jacek Karatekin, Ozgur Kasaba, Yasumasa Kass, David Khatuntsev, Igor Kleinbehl, Armin Kokonkov, Nikita Krasnopolsky, Vladimir Kuzmin, Ruslan Lacombe, Ga√©tan Lanciano, Orietta Lellouch, Emmanuel Lewis, Stephen Luginin, Mikhail Liuzzi, Giuliano Lopez-Puertas, Manuel Lopez-Valverde, Miguel Maattinen, Anni Mahieux, Arnaud Marcq, Emmanuel Martin-Torres, Javier Maslov, Igor Medvedev, Alexander Millour, Ehouarn Moshkin, Boris Mumma, Michael J. Nakagawa, Hiromu Novak, Robert E. Oliva, Fabrizio Patsaev, Dmitry Piccialli, Arianna Quantin-Nataf, Cathy Renotte, Etienne Ritter, Birgit Rodin, Alexander Schmidt, Fr√©d√©ric Schneider, Nick Shematovich, Valery Smith, Michael D. Teanby, Nicholas A. Thiemann, Ed Thomas, Nicolas Vander Auwera, Jean Vazquez, Luis Villanueva, Geronimo Vincendon, Matthieu Whiteway, James Wilquet, Valerie Wolff, Michael J. Wolkenberg, Paulina Yelle, Roger Young, Roland Zasova, Ludmila Zorzano, Maria Paz Nature Geoscience 568 2019 7753 517-520 ozgur.karatekin@observatoire.be https://www.nature.com/articles/s41586-019-1096-4 4450312 http://publi2-as.oma.be/record/4932/files/s41586-019-1096-4.pdf 14650 http://publi2-as.oma.be/record/4932/files/s41586-019-1096-4.gif?subformat=icon icon 25806 http://publi2-as.oma.be/record/4932/files/s41586-019-1096-4.jpg?subformat=icon-180 icon-180 published in REFERD