This week, NASA's Curiosity Mars rover found a surprising result: the largest amount of methane ever measured during the mission - about 21 parts per billion units by volume (ppbv). One ppbv means that if you take a volume of air on Mars, one billionth of the volume of air is methane.

The finding came from the rover's Sample Analysis at Mars (SAM) tunable laser spectrometer. It's exciting because microbial life is an important source of methane on Earth, but methane can also be created through interactions between rocks and water.

Curiosity doesn't have instruments that can definitively say what the source of the methane is, or even if it's coming from a local source within Gale Crater or elsewhere on the planet.

"With our current measurements, we have no way of telling if the methane source is biology or geology, or even ancient or modern," said SAM Principal Investigator Paul Mahaffy of NASA's Goddard Spaceflight Center in Greenbelt, Maryland.

The Curiosity team has detected methane many times over the course of the mission. Previous papers have documented how background levels of the gas seem to rise and fall seasonally. They've also noted sudden spikes of methane, but the science team knows very little about how long these transient plumes last or why they're different from the seasonal patterns.

The SAM team organized a different experiment for this weekend to gather more information on what might be a transient plume. Whatever they find - even if it's an absence of methane - will add context to the recent measurement.

Curiosity's scientists need time to analyze these clues and conduct many more methane observations. They also need time to collaborate with other science teams, including those with the European Space Agency's Trace Gas Orbiter, which has been in its science orbit for a little over a year without detecting any methane.

Combining observations from the surface and from orbit could help scientists locate sources of the gas on the planet and understand how long it lasts in the Martian atmosphere. That might explain why the Trace Gas Orbiter's and Curiosity's methane observations have been so different.

Related Links
Mars Science Lab (Curiosity)
Mars News and Information at MarsDaily.com
Lunar Dreams and more

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Fly over Mount Sharp on Mars
Pasadena CA (JPL) May 21, 2019
Ever wanted to visit Mars? A new animated video shows what it would be like to soar over Mount Sharp, which NASA's Curiosity rover has been climbing since 2014. This video highlights several regions on the mountain that are intriguing to Curiosity's scientists, chief among them what the science team calls the "clay-bearing unit," where Curiosity has just started analyzing rock samples. The aerial tour also shows the roving science lab's proposed path in the years to come. Intriguing targets ... read more