A Startling Spike on Mars
Methane gas is a potential indicator of life on the red planet, but it’s proving difficult to track.
by MARINA KOREN
If humans ever discover life on Mars, this is how it might start: with a breaking-news alert heralding a startling development well beyond Earth.
On a recent Saturday afternoon, The New York Times sent a bulletin: “Mars is belching a large amount of methane gas. It’s a sign of possible life on the red planet.”
NASA quickly published a press release acknowledging the detection, which, the Times had reported, marked the largest amount of methane ever registered by the Curiosity rover, a NASA mission that touched down on the red planet in 2012. But after that, the agency went quiet. The news had come from an email between scientists on the Curiosity team that had been leaked to the Times. It wasn’t supposed to be known, at least not yet. And there’s no room for nuance in a breaking-news alert.
Like the Times, NASA provided an important caveat: Many things can produce methane on Mars. Alien life is on that list, but other sources are far more likely.
After decades of exploration, spacecraft haven’t found any evidence of life on the surface of Mars. But some scientists say it may lurk beneath the surface, in the form of tiny organisms. And that’s why methane is so noteworthy. On Earth, microbes pump the natural gas into the planet’s atmosphere. Perhaps a similar arrangement exists on Mars.
Methane doesn’t last forever in the Martian atmosphere, however. Exposure to the sun’s radiation, combined with reactions with other gases, breaks down the gas molecules within a few centuries. This chemistry is what makes the spike that Curiosity found so intriguing. If methane is present in the Martian atmosphere right now, it must have been released fairly recently. Detectable quantities might be a sign that something is alive on Mars, capable of replenishing the supply.
Or not. Natural interactions between rock and water can also produce the gas. The methane might have been forged deep beneath the Martian surface—where reservoirs of ancient water chafe against sediment—escaping into the atmosphere through a narrow crack in the ground. The whiff Curiosity caught might have been billions of years old.