A Head Start on Potential Hazards for Mars Explorers The New York Times

No little green men will be lurking behind boulders, ready to zap all comers with their deadly ray guns. But that hardly means the first humans to visit Mars will have nothing to fear. It is not too soon, scientists say, to start worrying about the potential Martian menace of killer dust. Scientists studying the risks facing human explorers of Mars have cautioned that windblown dust, pervasive on the arid planet, threatens to abrade, clog and corrode vital spacecraft systems. And some of the dust breathed by astronauts may contain one of the most toxic chemicals known, the cancer-causing hexavalent chromium.