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Methane eludes Curiosity in rover's first sniffs of Martian atmosphere

Elizabeth Howell, News Writer
Nov 5, 2012, 0:00 UTC

Sen—NASA's most powerful gas analyzer on Mars - on board the Curiosity rover - has found no definitive signs of methane yet at its landing site of Gale Crater, the agency said. But the rover is armed with the tools to keep searching. 

Methane is considered an important gas on Mars because it is sometimes, but not always, a sign of life. The gas can come from biological processes, or belch from the bellies of volcanoes, or be derived in other ways.

"Methane is clearly not an abundant gas at the Gale Crater site, if it is there at all," stated Chris Webster, a NASA Jet Propulsion Laboratory employee who is the lead investigator for Curiosity's tunable laser spectrometer.

Curiosity used its Sample Analysis of Mars (SAM) instrument to search for the gas with two methods - one using a mass spectrometer that looks at all atmospheric gases, and another using the laser spectrometer that narrows in on methane and carbon dioxide.

Neither method found any definitive sign of methane. Researchers say there is either no methane or perhaps just wisps of it, at a few parts of methane per billion parts of Martian atmosphere, by volume.

Methane has been spotted before on Mars, but it's hard to find as it does not appear to stick around in the atmosphere long. 

The European Space Agency's Mars Express saw methane from orbit in 2003. Six years later, American researchers independently announced they found signs of it in 2003 using NASA's Infrared Telescope Facility and the W.M. Keck telescope. The American scientists said plumes came during Mars' warmer months in the northern atmosphere, in areas that probably had ground ice or running water in the past. However, by 2006, ESA said, most signs of the gas had vanished. Researchers are interested in knowing what generates the methane and what might be removing it.

Processes that could produce methane on Mars include volcanism, the oxidation of iron, or possible Martian microbes hiding underground, according to NASA.

NASA is careful to say that Curiosity's results don't overrule the earlier findings of methane; the discrepencies just speak of how much we need to learn about the Red Planet's environment, researchers said.

Meanwhile, the rover - three months into a two year primary mission - is suggesting new ways of understanding how Mars lost so much of its atmosphere during its evolution.

Curiosity's SAM measurements of carbon and argon postulate the Martian environment is more favourable to keeping heavier isotopes, or variants of elements, than lighter ones in the atmosphere.

NASA hopes to gain more understanding of why when a future Mars orbital mission arrives, called Mars Atmosphere and Volatile Evolution or MAVEN. That is expected to start work in 2014.


Curiosity took this self-portrait on October 31, 2012. Curiosity's Mars Hand Lens Imager (MAHLI) was to capture the set of 55 high-resolution images were stitched together to create this full-color self-portrait. Images taken at Rocknest, Gale Crater. Credit: NASA/JPL-Caltech/Malin Space Science Systems

NASA's Mars Science Laboratory, also known as Curiosity, landed on Mars on August 6 (UTC). NASA's Jet Propulsion Laboratory (JPL), based in Pasadena, California, a division of the California Institute of Technology, manages the Mars Science Laboratory mission for NASA.