Methane, a gas that on Earth comes mainly from living organisms, spikes regularly on Mars but scientists have not been able to pinpoint the source, according to new research out Tuesday.
The latest findings from NASA's Curiosity rover, which has been exploring the Red Planet since it landed in 2012, were discussed at the American Geophysical Union meeting in San Francisco, and published in the US journal Science.
After poring over 20 months of data collected by the robotic vehicle, scientists found that methane on the dusty planet is far lower than expected, about half of what scientists thought they would detect from processes like the breakdown of dust and organic materials delivered by meteorites.
However, they also discovered that background levels of methane at Gale Crater, where the rover landed, "spiked about tenfold, sometimes over the course of just 60 Martian days, which was surprising because the gas is expected to have a lifetime of about 300 years," said the Science report.
"Their results suggest that methane is occasionally produced or vented near the Gale Crater -- and that the gas disperses quickly once these episodes of venting or production cease," it added.
Curiosity is not equipped to find out whether life currently exists on Mars, but the mission aims to uncover whether life ever arose there by looking for chemical elements that are the building blocks of life, including carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.