Did 'Martian' methane signal come from Earth?
By Rachel Courtland CLAIMS that Mars’s atmosphere contains methane, which have fuelled speculations that the planet hosts life, may be premature. A key piece of evidence for methane on Mars may actually be due to Earth-based methane, warn researchers led by Kevin Zahnle of NASA’s Ames Research Center in Moffett Field, California. “This is not a done deal,” says Zahnle, despite a widespread perception that methane has been found on the Red Planet. The clearest evidence for methane on Mars came in 2009 from a team led by Michael Mumma at NASA’s Goddard Space Flight Center in Greenbelt,