Methane has been discovered on Mars, raising the possibility of past or present life on the Red Planet, scientists said today.
The gas was detected recently using the Planetary Fourier Spectrometer (PFS) on the European Space Agency orbiter Mars Express.
Dr Vittorio Formisano, principal investigator of PFS, said the finding could either be evidence of life or of volcanic activity.
Many more observations and studies were required to identify the source of the methane, he added.
"Eventually we shall perhaps be able to identify the source of methane," said Dr Formisano.
"The source is going to be a rather big issue. The source could be either simply volcanic activity, or life of biological origin.
"I am not stating that there is life now. There is no conclusion yet."
The scientist said methane could only exist for a few hundred years in the Martian atmosphere.
This meant there could still be life or volcanic activity now on the Red Planet, report scotsman.com
According to BBC 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.
On Earth bacteria produce methane from hydrogen and carbon dioxide. Terrestrial microbes that produce methane do not need oxygen to thrive, and these are thought to be the type of microbes that could possibly live on Mars.
The twin rovers that landed on Mars in January will be unable to answer the question of the methane's origin as they are designed for geological work.
Future missions could include sensors to analyse the methane that may be able to determine if it is of biological origin. The failed Beagle 2 mission had a device that could have sniffed the Martian atmosphere for methane.
Earlier PRAVDA.RU quoted scientists have found further evidence that there may once have been life on Mars - the legacy of a salty sea. NASA researchers examining pictures taken by one of the Mars rovers scouring the red planet said they believed they had reached what used to be a sea shore.
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