The detection of methane near Gale Crater on Mars by the Mars Express spacecraft on 16 June 2013, is reported in Nature Geoscience this week. This finding provides independent confirmation of debated measurements obtained by the Curiosity rover one day earlier.

Methane was discovered in the Martian atmosphere more than a decade ago, and was thought to have been produced biologically by microorganisms or by abiotic geochemical reactions. However, the potential mechanisms for its generation as well as the reliability of existing detections have been the subject of vigorous debate.

Marco Giuranna and colleagues present spacecraft-based spectrometer observations of methane in the Martian atmosphere near Gale Crater, which constitute independent confirmation of the measurements from Curiosity. An investigation of the potential source of the methane, using numerical modelling and geological analysis, suggests that transient events in a region of faults near Gale Crater are likely to have released the detected methane into the Martian atmosphere. The identification of this location may provide focus for future investigations into the origin of methane on Mars.