The detection of methane on Mars in 2004 raised the tantalising possibility that the cold, dry planet now harbours life in the form of subsurface, methane-producing bacteria. Now, detailed observations suggest a way to potentially find any such life.
Nature News reports that observations made over the last four years show the gas is not spread evenly around the planet but concentrated in a handful of "hotspots".
The observations were reported at a planetary sciences meeting earlier this month by Michael Mumma of NASA's Goddard Space Flight Center in Greenbelt, Maryland. They show that methane clouds spanning hundreds of kilometres form over these hotspots and dissipate within a year - much shorter than the 300 years it was thought to take for atmospheric methane to be destroyed by sunlight. If methane is being destroyed so quickly, it must be created at far higher rates than previously thought, Mumma said at the meeting.
He reported similar findings in 2005 (see our story about them here), but at the time other researchers were sceptical of those preliminary observations. Now, the case for concentrated methane seems to be a lot stronger. "This is a big deal," Sushil Atreya of the University of Michigan told Nature.
Importantly, one of the hotspots, Nili Fossae (pictured), is one of the possible landing sites for the Mars Science Laboratory, a huge rover due to begin its journey to the Red Planet next year.
It is not, however, one of the top picks - last month scientists gave priority to three other possible landing sites, all craters thought to have once held water.
But the new observations might cause Nili Fossae, a fracture that has been eroded and partly filled in by sediments and clay-rich ejecta from a nearby crater, to rise in the rankings. "We're going to take this very seriously," MSL project scientist John Grotzinger of Caltech told Nature. The new results might be factored into a landing site meeting in early November, the story reports.
Grotzinger says he needs to see hard data to seriously consider reshuffling MSL's landing target choices. But if the MSL team decides to send the rover to Nili Fossae, the search for life on Mars could heat up very quickly. That's because MSL can detect the ratio of carbon isotopes in methane - so if Martian methane is rich in carbon-12, as is life on Earth, it might tilt the scales in favour of a biological origin for the gas.
What do you think - should MSL follow the methane?
Maggie McKee, space editor (Image: NASA/JPL/University of Arizona)
SWEET! Of course I have always wondered about caves and or sink-holes on Mars. If it was once like Earth, with surface water and an atmosphere capable of generating rain and what not... then there must be a good number of underground passage ways and caves which descend into the martian crust. It would be very exciting to explore such a thing is at all possible, no?