It may only be a very small part of Mars’ atmosphere but methane waxes and wanes with the seasons, scientists say, reports BBC.
The discovery made by the Curiosity rover is important because it helps narrow the likely sources of the gas. On Earth, those sources largely involve biological emissions - from wetlands, paddy fields, livestock and the like. No-one can yet tie a life signature to Mars’ methane, but the nature of its seasonal behaviour probably rules out some geological explanations for it.“For the first time in the history of Mars methane measurements, we have something that’s repeatable,” said Dr Chris Webster, a US space agency (Nasa) scientist working on Curiosity.
“It’s like trying to find a fault on your car. If it’s intermittent you can never solve it, but if you’ve got some repeatability you’ve got some chance of understanding it,” he told BBC News.
Methane in Mars’ atmosphere is a fascinating topic. The gas is short-lived so the fact that it persists in the planet’s air points to a constant, on-going source - and given CH₄’s link to biology on Earth, scientists need to get to the bottom of this martian mystery.
Ever since it landed in the Red Planet’s equatorial Gale Crater in 2012, Curiosity has been sniffing the air for methane.
The roving robotic laboratory has seen wafts where the concentration has risen upwards of seven parts per billion (ppb) (by comparison, on Earth it is about 1,860ppb). But over the past few years, the one-tonne vehicle has also been tracking the general background trend.
It is this behaviour that Dr Webster and colleagues report in Science Magazine this week.They show methane rises from just above 0.2ppb in the northern hemisphere winter to a fraction over 0.6ppb in the summer.