Methane poses Mars life puzzle BBC

Methane has been found in the Martian atmosphere which scientists say could be a sign of present-day life on Mars. It was detected by telescopes on Earth and has recently been confirmed by instruments onboard the European Space Agency’s orbiting Mars Express craft. Methane lives for a short time in the Martian atmosphere so it must be being constantly replenished. There are two possible ways to do this. Either active volcanoes, but none have yet been found on Mars, or microbes.