Big methane discovery on Mars: There isn't any methane. (+video)
NASA's Mars rover Curiosity has detected no trace of methane, contradicting earlier observations that suggest that the organic molecule might be present on the Red Planet.
NASA's Mars rover Curiosity has revealed no trace of methane, a potential sign of primitive life, on the Martian surface, contradicting past evidence of the gas spotted by spacecraft orbiting the Red Planet, researchers say.Skip to next paragraph
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The Mars methane discovery, or rather the lack thereof, adds new fuel to the debate over whether the gas is truly present on Mars. And not all scientists are convinced that methane is missing on Mars.
The first and only attempts to search for life on Mars were the Viking missions, launched in 1975. Those probes failed to find organic compounds in Martian soils, apparently ruling out the possibility of extant life on the Red Planet. [7 Biggest Mars Mysteries of All Time]
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But in the past decade, probes orbiting Mars and telescopes on Earth have detected what appeared to be plumes of methane gas from the Red Planet. The presence of colorless, odorless, flammable methane on Mars, the simplest organic molecule, helped revive the possibility of life once existing, or even currently living, just below the planet's surface.
On Earth, much of the methane in the atmosphere is released by life-forms, such as cattle. Scientists have suspected that methane stays stable in the Martian atmosphere for only about 300 years, so whatever is generating this gas did so recently.
Now, the new findings from NASA's Curiosity rover unveiled online today (Sept. 19) in the journal Science suggest that, at most, only trace amounts of methane exist on Mars.
"Because methane production is a possible signature of biological activity, our result is disappointing for many," said study lead author Christopher Webster, an Earth and planetary scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
But the findings still puzzle scientists.
"It's a mystery surrounded by an enigma here," said imaging physicist Jan-Peter Muller of University College London, who is a Curiosity rover science team member but is not one of the authors of this latest Mars methane study. "This clearly contradicts what has been measured from space and from Earth."
Methane mystery on Mars
The Curiosity rover has analyzed the surface and atmosphere of Mars with an arsenal of advanced scientific instruments ever since its spectacular landing on Mars in August 2012. Measurements from the rover's Tunable Laser Spectrometer, a device specially designed for measuring the gas on Mars, say the most methane that could currently exist in the Martian atmosphere is 1.3 parts per billion by volume. [Latest Mars Photos by the Curiosity Rover]
"Based on earlier observations, we were expecting to land on Mars and measure background levels of methane of at least several parts per billion, but saw nothing," Webster told SPACE.com.
When the researchers first looked for methane using Curiosity, they found strong signals that they quickly realized were coming from the little methane that they had taken with them, Webster said — that is, "'Florida air' that had leaked into one chamber during the long prelaunch activities. This contamination has been removed in stages, but each attempt to look for methane from the Mars atmosphere has resulted in a non-detection."
The original plan of the researchers was to analyze the carbon isotope ratios of methane on Mars to get insight on whether that gas could be biologically produced. "However, the lack of significant methane has denied that latter experiment," Webster said.