Methane is a greenhouse gas present in the atmospheres of both Earth and Mars. If a class of ancient microbes called Archaea are the source of Mars' methane, as some scientists have proposed, then unmanned probes to the Martian surface should look for them at depths where the temperature is about 10 degrees Celsius (18 degrees Fahrenheit) warmer than that found at the base of the Greenland ice sheet, according to UC Berkeley lead researcher P. Buford Price, a professor of physics.
This would be several hundred meters - some 1,000 feet - underground, where the temperature is slightly warmer than freezing and such microbes should average about one every cubic centimeter, or about 16 per cubic inch.
While Price is not expecting any time soon a mission to Mars to drill several hundred meters beneath the surface, methanogens (methane-generating Archaea) could just as easily be detected around meteor craters where rock has been thrown up from deep underground.
"Detecting this concentration of microbes is within the ability of state-of-the-art instruments, if they could be flown to Mars and if the lander could drop down at a place where Mars orbiters have found the methane concentration highest," Price said. "There are oodles of craters on Mars from meteorites and small asteroids colliding with Mars and churning up material from a suitable depth, so if you looked around the rim of a crater and scooped up some dirt, you might find them if you land where the methane oozing out of the interior is highest."
Price and his colleagues published their findings last week in the Early Online edition of the journal Proceedings of the National Academy of Sciences, and presented their results at last week's meeting of the American Geophysica
Source:University of California - Berkeley