Methane 'belches' detected on Mars

Nasa's Curiosity rover has detected methane on Mars - a gas that could hint at past or present life on the planet. The robot sees very low-level amounts constantly in the background, but it also has monitored a number of short-lived spikes that are 10 times higher. Methane on the Red Planet is intriguing because here on Earth, 95% of the gas comes from microbial organisms. Researchers have hung on to the hope that the molecule's signature at Mars might also indicate a life presence.