Last Update: Monday, March 29, 2004. 9:19pm (AEST)
Scientists studying Mars say they have found evidence of methane in the atmosphere of the Red Planet, which they say could be a sign of present day life.
It was detected by telescopes on Earth and has recently been confirmed by instruments onboard the European Space Agency's orbiting Mars Express craft.
According to the scientists, methane does not last for long in the Martian atmosphere and is being constantly replenished.
It is possible that there are active volcanoes on the planet, but no evidence of activity has been found so far.
The other more controversial theory is that living bacteria, similar to that on Earth, are producing the methane.
--BBC