Pretty important discovery coming out of NASA HQ yesterday: methane on Mars. If you think you may have heard this claim before, it’s probably because you have. In 2004, a group claimed to have detected the gas in the martian atmosphere, but the data wasn’t overly convincing, and interest faded. Yesterday’s announcement of data (see the story here) from way back in 2003 changes things, providing an all-important second data set confirming the inital claim. The discovery identifies 3 regions on Mars where the gas was coming from: Terra Sabae, Nili Fossae and Syrtis Major.

So why is the discovery of localized methane sources interesting? As far as we know, the gas is made either volcanically or by a class of microbes known as methanogens. To make things more interesting, methane is broken down in the martian atmosphere, meaning that it could only last a few years or decades before being extinguished. This suggests that the gas has been released recently, not necessarily that it has been produced recently – an important distinction. The study’s lead author, Michael Mumma, points out that the gas could have been produced long ago and released only recently as subsurface ground thawed.

The jury’s still out on the source, but the important thing is that methane seems to be there. The next best chance of further observation is the Mars Science Laboratory mission, which recently passed over one of the three methane sites, Nili Fossae, as a potential landing site. But the mission’s recent delay, from this year to 2011, might re-open the door. Mission planners admitted the possibility at yesterday’s news conference, but they’d have some catching up to do. Previous studies have shown that Nili Fossae is high in clays and contains the mythical martian carbonates – both of which are often associated with life. Seems like it’s worth a second look…