Mars just seems to be the one planet (aside from our own, of course) that we humans can’t get enough of. For hundreds of years, we’ve been writing about it, wondering if Martians are going to come to visit us or hoping Matt Damon can get home from the strange Red Planet. Let’s face it: we’re obsessed. But there’s a good reason for us to be; with so many interesting discoveries and potential signs of life, Mars just keeps pulling us in. And now, with recent discoveries about methane on the Red Planet, we may be one step closer to discovering life on Mars.

Recent Methane Discoveries

Scientists have known for a while that there’s methane on Mars. In fact, they even know it goes through cycles of intensity. While background levels of methane on some parts of Mars normally hover around .24-.65 ppb (parts per billion), the levels do increase, and peak during the northern summer on the planet. Our favorite Martian robot, Curiosity, however, recently discovered something pretty weird about those methane levels.

Back in 2013, Curiosity detected an enormous spike of methane levels on Mars. The levels jumped to 6ppb, which is a huge difference compared to the usual background levels of methane on the planet. But that’s not even the biggest spike. Just a day later, a group of researchers led by Marco Giuranna saw another huge spike, this time all the way up at 15.5ppb. That’s an enormous difference!

Verifying This Is Actually Anything But Easy

Considering all the equipment we have trained on Mars, verifying these methane levels are anything but straightforward (these 2013 observations were only verified recently). When Curiosity first detected the spike, some scientists thought it must have been an equipment fluke or malfunction, because the levels were simply so high. When Giuranna’s team noticed the secondary spike (which was a totally accidental overlap of observations), scientists were more willing to accept that the findings were accurate.

Despite all the technology we have to study this planet, it’s actually really hard to observe methane emissions. Spacecraft that are orbiting the Red Planet have a hard time documenting methane just because there’s so little of the gas, and because it has weak absorption. It’s surprisingly hard to measure Mars’ methane levels from Earth, too, because our planet has so much methane that it interferes with observations of our planetary neighbor.

So, Where Is All This Methane Coming From?

Curiosity found its methane spike about 300 miles east of the Gale Crater on Mars, in an area called Aeolis Mensae. By sheer dumb luck, Giuranna’s team was observing the same area, which is how they were able to combine and compare observations. But those observations weren’t enough to determine the exact source of the methane.

To try to determine exactly where this methane was coming from, scientists divided the Gale Crater area into large squares and ran computer simulations (one million of them) to determine possible sources that may be emitting the gas. They also studied the squares to try to find probable methane sources with physical observations. To their surprise, even though the two studies were conducted separately, they both pointed towards the probability that the methane gas had been trapped under ice. When the ice was broken, the methane gas was probably released.

Could Methane Mean Life?

We’re still not sure if the methane was emitted recently, or if it’s been sitting under the ice for eons and only recently released from the ice. But what’s really interesting is that methane is usually a gas produced by microbial life forms. While it can also be produced by other things (like your typical everyday chemical reaction), some scientists remain hopeful that the methane could reveal traces of life forms, even if they are trapped beneath the ice. We’re far from a certain answer, but with more discoveries like this, we grow closer to an answer every day.