Spike seen in methane on Mars, but source unknown

Methane, a gas that on Earth comes mainly from living organisms, has been measured for the first time making a sudden spike on Mars, leaving scientists puzzled about its origin.
      
The latest findings from NASA's Curiosity rover, which has been exploring the Red Planet since it landed in 2012, were published in the US journal Science on Tuesday and raise the question, could microbes be the source of the methane? And what caused the levels to soar and dissipate again in a matter of weeks?       

While the discovery of life on Mars would be a major breakthrough, NASA's John Grotzinger cautioned that the findings do not mean that scientists have found evidence of life on Mars, and more investigation is needed.
      
However, he told reporters at the American Geophysical Union conference in San Francisco that the discovery was "really exciting news" because "it is the kind of material that you would look for if life ever originated on Mars."        

"We now have full confidence that there is methane occasionally present in the atmosphere of Mars," said Grotzinger, NASA Curiosity project scientist at the California Institute of Technology.
      
"And that there are organics preserved in ancient rocks on Mars in certain places."        

The methane and the organic molecules from a rock-powder sample collected by rover's drill "can both be consistent with the former presence of life or the existing presence of life," Grotzinger said.
                      
Mars is widely believed to have once been warm and wet, and potentially welcoming to some form of life in the distant past.
      
Curiosity is not equipped to find out whether life currently exists on Mars, but the mission aims to uncover...