Finally, independent measurements report a firm detection in the Martian atmosphere above Gale Crater on 16 June 2013 by the Planetary Fourier Spectrometer onboard Mars Express, one day after the in situ observation of a methane spike by the Curiosity rover.
Methane was not detected in other orbital passages and this detection involved improved observational geometry as well as enhanced data treatment and analysis.
The team also created simulations of the Martian atmosphere using various gas release scenarios to identify a potential source region east of Gale Crater and speculation points to faults of Aeolis Mensae which may extend into proposed shallow ice of the Medusae Fossae Formation which could mean sporadic release of the gas trapped below or within the ice.
But it's wise not to let media claims trumpet another 'life on other planets' narrative by pretending to ask 'is this a sign of life on other planets?' and claiming that's science journalism.
“In general we did not detect any methane, aside from one definite detection of about 15 parts per billion by volume of methane in the atmosphere, which turned out to be a day after Curiosity reported a spike of about six parts per billion,” says lead author Marco Giuranna from the Institute for Space Astrophysics and Planetology in Rome.
Citation: Marco Giuranna, Sébastien Viscardy, Frank Daerden, Lori Neary, Giuseppe Etiope, Dorothy Oehler, Vittorio Formisano, Alessandro Aronica, Paulina Wolkenberg, Shohei Aoki, Alejandro Cardesín-Moinelo, Julia Marín-Yaseli de la Parra, Donald Merritt&Marilena Amoroso, Independent confirmation of a methane spike on Mars and a source region east of Gale Crater, Nature Geoscience https://www.nature.com/articles/s41561-019-0331-9