Rush Hour on Mars

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Pillinger's visions helped get his project funded. He trawled around the U.K., begging businesses, government authorities and research facilities for resources to develop the project, eventually landing some $60 million in cash and in-kind help. British pop band Blur and artist Damien Hirst gave works that Beagle will carry to Mars. Eventually the Department of Trade and Industry kicked in an $8 million grant. "Just building a lightweight, university-driven probe, and showing that much less demanding technology is needed, is in itself a triumph," says respected biomedical engineer Heinz Wolff. How will the probe know if there is life on Mars? The planet's surface is a dry and frozen desert, seemingly hostile to any life-forms. But astronomers say it was once covered in rivers, lakes and possibly oceans; NASA 's Mars Odyssey satellite, currently in orbit around the planet, has detected huge quantities of ice just a few feet below the surface. Beagle will search for evidence that these areas have supported extremophiles, micro-organisms living deep underground or in extremes of heat, pressure or toxicity, that represent a kind of rock-bottom definition of a living form. Many examples of these have been studied on Earth, including recent samples found 4 km beneath the surface, in a South African mine. One suggestion of Martian life emerged in 1996, when a meteorite from Mars that landed in the Antarctic region was found to contain what seemed to be fossilized microbial life. But the results are inconclusive; Pillinger and others argue that the fossils could have stemmed from contamination on Earth rather than true evidence of life on Mars.

What distinguishes the Beagle's mission is that it will effectively carry out tests in situ on organic matter. If all goes well, the Beagle's robotic paw will scratch and claw at nearby rocks, sniffing for the trace gases, organic compounds and complex chemicals. Soil samples will be dug out using the mole, a robot that can tunnel deep beneath the surface. Any life on Mars, past or present, would leave its chemical imprint — or 'fossil' — inside the rock. Pillinger's team has developed a miniaturized gas analysis package (GAP) to heat up rock and soil in an oven, process the gases released and analyze them using a mass spectrometer (which measures elements in minute quantities). By recording the temperature at which the heated samples release carbon dioxide, scientists can gauge the presence of a particular carbon isotope that indicates life.

Other tests will look for methane, since extremophiles fuel themselves by reducing carbon dioxide to methane. On the surface, methane is readily destroyed by chemical reactions. If the Beagle detects even minute levels of methane, a continuous supply must be assumed, and biological activity will be the most likely reason.

There are, of course, risks. Mars has been exceptionally hostile to visitors: fewer than 10 of the 31 missions to the planet have succeeded. But if any of these missions can break the jinx, they might unravel a bewitching mystery. And if the little pod called Beagle takes the prize, somewhere Charles Darwin will be smiling.