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, say researchers led by Kevin Zahnle of the NASA 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, Maryland. They used ground-based telescopes to look at light emitted by Mars and attributed dips in the spectrum to martian methane absorbing those frequencies.
The readings, taken several years apart, suggested that methane's lifetime in the Martian atmosphere is unexpectedly – and inexplicably – short. While most researchers have assumed that this was due to an as-yet-unknown Martian process, Zahnle's team offers an alternative explanation: the dips in the spectrum are not due to alien methane.To read the rest of the article, click here.