Exciting news from the surface of Mars, this week. After a couple of false starts, the good people of NASA have confirmed that they have detected the presence of methane on Mars:

A year after reporting that NASA’s Curiosity rover had found no evidence of methane gas on Mars, all but dashing hopes that organisms might be living there now, scientists reversed themselves on Tuesday.

Curiosity has now recorded a burst of methane that lasted at least two months.

This is exciting for two reasons. First, methane doesn’t last long on the surface of Mars, so it must have been created within the last few hundred years. Second, there are only two possible sources we know about, both of which would improve the chances that life exists in some form on Mars:

It could have been created by a geological process known as serpentinization, which requires both heat and liquid water. Or it could be a product of life in the form of microbes known as methanogens, which release methane as a waste product.

Even if the explanation for the methane turns out to be geological, the hydrothermal systems would still be prime locations to search for signs of life.

It’s always possible there is another explanation for the presence of methane on Mars, and scientists will no doubt be working diligently to eliminate those other possibilities in the months ahead, but if the finding holds up, we could be on the cusp of a truly significant breakthrough in the hunt for alien life.