Curiosity samples methane surges in Martian atmosphere

On Earth, the majority of the methane that finds its way into the atmosphere is produced by microbes. Once in the atmosphere, the gas is broken down by a number of processes, so its continued presence there is a testimony to Earth's activity, both biological and geological.

Mars' atmosphere breaks down methane as well, but there are also low levels of methane in its atmosphere. Although this methane could come from sources that don't involve biological or geological activity, some Earth-based observations had suggested that Mars had localized sources that create plumes of methane in its atmosphere. Those are tougher to explain, but the observations have been difficult to replicate.

Now, the Curiosity rover has settled the issue, observing spikes in the atmosphere's methane concentration that seem to indicate a sporadic, local source.