Tuesday, 20 January 2009 by bbbeard.

“I have a dream that my four little children will one day live in a nation where they will not be judged by the color of their skin but by the content of their character.”

Well, maybe someday my grandchildren will live in such a country.

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Friday, 16 January 2009 by lukemeister.

NASA held an interesting press conference yesterday about the discovery of localized emissions of methane from Mars. The discovery of Martian methane, using both ground-based telescopes and a spacecraft orbiting Mars, was reported in 2003, but the detections weren’t certain. Now high-resolution infrared spectra taken by Michael Mumma at NASA/Goddard and colleagues, reported online in Science, seems to provide definitive measurements. The CH₄ appears to arise from three regions near or within Arabia Terra, Nili Fossae, and Syrtis Major. The most intriguing observation in the new study is that the atmospheric abundance of methane dropped by a factor of two between 2003 (northern summer on Mars) and 2006 (vernal equinox on Mars), possibly suggesting a seasonal cycle. Methane has a lifetime of centuries against destruction by ultraviolet light from the Sun, so there must be another sink, possibly involving reactions with perchlorate or peroxide in the Martian soil.

On Earth most methane is generally thought to originate biologically, although it can also be produced through serpentinization, which involves the reaction of minerals like olivine and pyroxene with water and carbon dioxide. Both biological and abiological origins for Mars’ methane are in play. If martian microbes exist, their metabolism might resemble that of organisms found at 3 km depth in a gold mine in South Africa. Even if Martian methane originates abiologically, the new observations seem to imply that Mars shows a surprisingly high level of geological activity, as serpentinization on Earth is associated with hydrothermal systems.

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