It can be produced by non-biological processes: it can be found in vast quantities on the giant gas planets — Jupiter, Saturn, Uranus and Neptune. There it is thought to be leftover material from the birth of the Solar System.
But on a small rocky plant like Earth, it is most commonly the result of biological processes; whether it’s the farts of cows and termites or the decay of vegetable matter in swamps.
And now it has been found, in huge, unpredictable ‘plumes,’ on Mars.
It’s been recorded before: in 2003 and 2004 for example. Using a the Infrared Telescope Facility in Hawaii and at the Gemini South Telescope in Chile, a NASA team led by Michael Mumma detected methane in the Martian atmosphere that appeared to come and go with the seasons.
“The methane mystery continues”
The Mars Express Orbiter found smaller quantities of the gas, suggesting that whatever was producing methane on Mars was taking a rest.
This week, whatever was resting has just woken up. The Mars Curiosity rover detected a plume of methane some three times stronger than one that it found in 2013.
Excited scientists ran followup tests and found that the gas had gone again. Paul Mahaffy, the principal investigator for Curiosity’s Sample Analysis instrument philosophically said “A plume came and a plume went.”
He continued: “With our current measurements, we have no way of telling if the methane source is biology or geology, or even ancient or modern.”
Curiosity doesn’t have instruments that can definitively say what the source of the methane is, or even if it’s coming from a local source within Gale Crater or elsewhere on the planet.
There’s no certainty that it’s being produced by living Martian organisms, but there’s also no better explanation for what process could produce methane in these sudden, intense, bursts without life being involved.
“The methane mystery continues,” said Ashwin Vasavada, Curiosity’s project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “We’re more motivated than ever to keep measuring and put our brains together to figure out how methane behaves in the Martian atmosphere.”