Martian methane points to possible life on the Red Planet
Cows and Mars have at least one thing in common — methane. Like flatulent (or farting) cows that produce the gas, the Red Planet releases clouds of methane, according to a recent study. Researchers wonder whether colonies of bacteria hidden beneath Mars’ red surface could be the cause.
The gas comes from three different areas of the planet, reports Mike Mumma, a NASA scientist at the Goddard Space Flight Center in Greenbelt, Md. At each location, the amount of methane fluctuated throughout the year. The biggest plumes were in the Martian summer and the smallest during the planet’s winter.
Other research teams have claimed to find Martian methane, but this was the first time that anyone could say so for sure.
Detecting the methane clouds was no easy task. The scientists measured Mars’ methane levels for three Martian years (equivalent to seven Earth years) using three special telescopes on Earth. These instruments can detect an invisible kind of light called infrared light. Scientists use these infrared telescopes to measure gases in space. But since the telescopes were on Earth, they also measured gases in our atmosphere. So the scientists had to use some tricks to figure out which gases came from Earth and which came from Mars.
“Mumma and his team have been painstakingly careful,” says Christopher Chyba, an astrobiologist (someone who studies extraterrestrial life) at Princeton University. “The reward is that we have observations of methane that show variations over season and by location. It’s fantastic.”
Methane is an unstable compound. Unless there is a constant source of the gas, the methane on Mars would eventually disappear. Spotting the methane over several years means that it is replenished regularly, Mumma said.
The scientists don’t know for sure what is causing methane to spew from Mars’ rocky floor. But they have a couple ideas. It could be that the gas is trapped in ice-covered rocks. In the summer, the planet warms, and the ice melts. Then the gas could slip out of cracks in the rock. When winter rolls around again, the ice reforms and plugs up the leaks. That could explain why there is more methane in the summer than in the winter.
In the other scenario, the methane is still trapped, but this time it’s locked inside little molecular cages called clathrates. These are basically chunks of ice with lots of methane inside. The summer sun unlocks the cages and frees the methane.
Neither of these hypotheses explains what creates the methane in the first place. That is still a bit of a mystery. About 90 percent of the methane in Earth’s atmosphere comes from livestock and rotting plants, but bacteria also create the gas. It’s possible that Mars’ methane could be coming from bacteria too. But it’s too soon to say. There is not enough evidence yet to say one way or another, Chyba says. That will be the next challenge for Mumma and his team — finding out if living organisms on Mars produce all that methane.
J. Bell/Cornell, M. Wolff/Space Science Institute, NASA, ESA, the Hubble Heritage Team (STScI/AURA)