Methane found on Mars; ergo Mars is not a dead planet

Here's a fairly big piece of news from today that is getting some attention:

New research reveals there is hope for Mars yet. The first definitive detection of methane in the atmosphere of Mars indicates the planet is still alive, in either a biologic or geologic sense, according to a team of NASA and university scientists.

"Methane is quickly destroyed in the Martian atmosphere in a variety of ways, so our discovery of substantial plumes of methane in the northern hemisphere of Mars in 2003 indicates some ongoing process is releasing the gas," said Dr. Michael Mumma of NASA's Goddard Space Flight Center in Greenbelt, Md. "At northern mid-summer, methane is released at a rate comparable to that of the massive hydrocarbon seep at Coal Oil Point in Santa Barbara, Calif."

Methane -- four atoms of hydrogen bound to a carbon atom -- is the main component of natural gas on Earth. It's of interest to astrobiologists because organisms release much of Earth's methane as they digest nutrients. However, other purely geological processes, like oxidation of iron, also release methane. "Right now, we don’t have enough information to tell if biology or geology -- or both -- is producing the methane on Mars," said Mumma. "But it does tell us that the planet is still alive, at least in a geologic sense. It's as if Mars is challenging us, saying, hey, find out what this means." Mumma is lead author of a paper on this research appearing in Science Express Jan. 15.

If microscopic Martian life is producing the methane, it likely resides far below the surface, where it's still warm enough for liquid water to exist. Liquid water, as well as energy sources and a supply of carbon, are necessary for all known forms of life.

Space.com also has a separate article about the source of this methane and why it's such a big deal:

Although the amount of Martian methane is small (10 parts per billion compared to 1,800 parts per billion on Earth), it appears to be concentrated in regions around the equator. Because these methane "clouds" only last a year before dispersing, the methane sources must be fairly localized and constant.

and how to measure it in greater detail:

The alternative is to use an optical spectrometer, which measures the frequencies at which a gas absorbs light. These so-called resonant frequencies depend on which isotopes make up the molecules in the gas.

The Mars Science Laboratory (MSL) - now scheduled to launch in 2011 - will carry such an optical spectrometer (the Tunable Laser Spectrometer, or TLS). This device may be able to measure the carbon isotope ratio in Martian methane, but Onstott does not think it will be able to say unequivocally whether life or geology is the source.

For this reason, he and his colleagues are designing a special kind of optical spectrometer, called a cavity ring-down spectrometer (CRDS), that will be 1,000 times more sensitive than TLS. The CRDS works by illuminating an atmospheric sample with a laser whose frequency can be tuned to resonate with methane molecules of a particular isotopic configuration.