Short bursts of Martian methane have been discovered by NASA's Curiosity rover, in a find that goes against previous reports stating that were was none. This change suggests that something must be sporadically creating the gas, but right now, no one's really sure what. 

What we do know is that 90 percent of the methane molecules here on Earth are produced by something that is, or once was, living, either of which would be a pretty mind-blowing possibility for Mars. But before we get too excited, we're far from any kind of discovery like that at this stage. 

"They're very exciting measurements," one of the team behind the find, Christopher Webster from NASA's Jet Propulsion Laboratory in the US, told Lisa Grossman at New Scientist. "They've completely opened up the debate again on Mars methane."

According to Alan Duffy from Swinburne University of Technology, the Mars Curiosity rover has been analysing the Martian air over the past 20 months, and over a two-month period in late 2013 to early 2014, they detected a 10-fold increase in the amount of methane present. This amount was detected on four separate occasions. 

Why did the discovery take so long to report? Grossman reports at New Scientist that these methane bursts are just 7 parts per billion, while on Earth, levels of methane are hundreds of times higher. "Measuring this tiny amount is an incredible achievement itself," she says.

Figuring out exactly where the methane came from is the next very tricky part of the process. 

"On Earth we know that most of the methane in our air is from the actions of living creatures and this is why we're so excited to track down the methane on Mars," said Duffy in an email. "Unfortunately life is just one of the possible causes for the methane on Mars, so detecting the gas doesn't tell us if the Red Planet still hosts life."

Duffy suggests that the methane could be coming from the break down of organic - but not living - chemicals on the surface of Mars by UV radiation from the Sun. Or perhaps it's the result of a reaction that occurred long ago between Olivine - a group of iron-magnesium silicate minerals found in Martian rocks - and water molecules, and the methane accumulated and got trapped in a chemical lattice called a clathrate

If these clathrates were disturbed for some reason, they could suddenly release the methane gas again, in short little bursts. This doesn't discount the possibility that this trapped methane was one produced by biological processes, adds Duffy, "but it might be that the gas has been trapped in a clathrate long after life has become extinct, meaning Mars could still be a dead world."

On top of the discovery announced last week that a once-habitable lake covered a region called the Gale Crater, which served as Curiosity's landing site in August 2012, the rover has also detected the first evidence of organic compounds on Mars, in crushed up rock samples. The finds suggest that over billions of years, changing conditions have forced the now dry and rocky planet to lose every skerik of its water, and with the help of the MAVEN Mars orbiter scientists are now collecting more data to piece together those circumstances. 

The findings have been published in the journal Science.

Source: New Scientist