title: Detection of methane in the atmosphere of Mars.
abstract: We report a detection of methane in the martian atmosphere by the Planetary Fourier Spectrometer onboard the Mars Express spacecraft. The global average methane mixing ratio is found to be 10 +/- 5 parts per billion by volume (ppbv). However, the mixing ratio varies between 0 and 30 ppbv over the planet. The source of methane could be either biogenic or nonbiogenic, including past or present subsurface microorganisms, hydrothermal activity, or cometary impacts.
authors.affiliation: Istituto di Fisica dello Spazio Interplanetario INAF-IFSI, Via del Fosso del Cavaliere 100, 00133 Rome, Italy. formisan@nike.ifsi.rm.cnr.it
authors.forename: Vittorio
authors.initials: V
authors.lastname: Formisano
authors.forename: Sushil
authors.initials: S
authors.lastname: Atreya
authors.forename: Thérèse
authors.initials: T
authors.lastname: Encrenaz
authors.forename: Nikolai
authors.initials: N
authors.lastname: Ignatiev
authors.forename: Marco
authors.initials: M
authors.lastname: Giuranna
mesh_terms: D001105:Archaea; D001272:Atmosphere; D001419:Bacteria; D018559:Exobiology; D005118:Extraterrestrial Environment; D006859:Hydrogen; D018535:Mars; D019110:Meteoroids; D008697:Methane; D011312:Pressure; D018531:Spacecraft; D017550:Spectroscopy, Fourier Transform Infrared; D018707:Volcanic Eruptions; D014867:Water
chemical_list: D014867:Water; D006859:Hydrogen; D008697:Methane