On Earth, the gas can be generated by geological processes, but much of it is released by micro-organisms known as methanogens, some of which live in the guts of ruminant animals.
The two parallel experiments determined the most likely source of methane on Mars to be an ice sheet east of Gale Crater.
In the latest study, Marco Giuranna and colleagues at the National Institute of Astrophysics in Rome turned to an instrument on the European Space Agency's Mars Express orbiter to look for more evidence of methane on Mars.
Giuranna said that while methane is a sign of life on Earth, its presence on Mars doesn't necessarily constitute evidence of something similar on the Red Planet.
Despite some speculation over methane on Mars, a group of scientists made a decision to conduct an independent investigation to see if the gas might exist on the Red Planet. Long periods of time have passed without any methane being detected in the atmosphere at all. The instrument spotted methane only once, on the same day Curiosity detected the sudden spike in the gas. Current thinking is that a break in the Martian permafrost allowed for a significant release of methane gas.
Vivek Oberoi's PM Narendra Modi postponed by a week? Here's the answer
Yadav's counsel said the court had refused to interfere as the Election Commission had already taken cognisance of the film. We are not projecting him as a hero, he is already a hero, not only for me but for crores of people in India and overseas .
But that has all changed thanks to a re-analysis of the original data that shows methane is definitely detectable on Mars.
"Despite various detection's reported by separate groups and different experiments, and although plausible mechanisms have been proposed to explain the observed abundance, variability and lifetime of methane in the current Martian atmosphere, the methane debate still splits the Mars community".
In an attempt to trace the source of the methane, the scientists divided up a wide region around Gale crater into a grid with squares 250km on each side.
While the Curiosity rover measured a methane concentration of 5.78 parts per billion (ppb) in the Gale crater on June 16, 2013 the PFS recorded 15.5 ppb in the column of atmosphere above the crater, the report said. Meanwhile, Curiosity rover data can also be questioned as the methane might potentially come from the rover itself - although that possibility was previously ruled out by the Curiosity team. Something similar may be happening on Mars, in this case, along the faults of the Aeolis Mensae region.
"Our results support the idea that methane release on Mars might be characterized by small, transient geological events rather than a constantly replenishing global presence, but we also need to understand better how methane is removed from the atmosphere, and how to reconcile the Mars Express data with results from other missions", adds co-author Frank Daerden from the Royal Belgian Institute for Space Aeronomy in Brussels.