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

2019; Nature Portfolio; Volume: 568; Issue: 7753 Linguagem: Inglês

10.1038/s41586-019-1096-4

1476-4687

Oleg Korablev, Ann Carine Vandaele, Franck Montmessin, Anna Fedorova, Аlexander Trokhimovskiy, F. Forget, Franck Lefèvre, Frank Daerden, Ian Thomas, Loïc Trompet, Justin Erwin, Shohei Aoki, Séverine Robert, Lori Neary, S. Viscardy, A. Grigoriev, N. Ignatiev, Alexey Shakun, Andrey Patrakeev, Denis Belyaev, Jean-Loup Bertaux, Kevin Olsen, Lucio Baggio, Juan Alday, Yuriy Ivanov, Bojan Ristic, Jon Mason, Yannick Willame, C. Depiesse, Laszlo Hetey, Sophie Berkenbosch, Roland Clairquin, Claudio Queirolo, Bram Beeckman, Eddy Neefs, Manish Patel, G. Bellucci, J. J. López‐Moreno, Colin Wilson, Giuseppe Etiope, Л. М. Зеленый, H. Svedhem, Jorge L. Vago,

Scientific Research and Discoveries

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. Highly sensitive measurements of the atmosphere of Mars with the ExoMars Trace Gas Orbiter do not detect any methane over a range of latitudes in both hemispheres, in contrast to previous local or remote detections.