Scientists have tried to find out how the planet\'s environment came to contain methane gas, which contains carbon — a substance found in all living things. Methane is more often associated with life so does this mean there is Martian life? Recent research has found that meteorites, which continually bombard the surface of Mars, contain enough carbon compounds to generate methane when they are exposed to sunlight. Researchers say their findings give valuable insights into the planet\'s atmosphere composition and sources. Methane is created on Earth by microorganisms thru the process of methanogenesis. It is carried into the stratosphere by rising air in the tropics. It has a net lifetime of about 10 years, and is primarily removed by conversion to carbon dioxide and water Researchers carried out experiments on samples from the Murchison meteorite, which fell on Australia more than 40 years ago. The team took particles from the rock — which has a similar composition to meteorites on Mars — and exposed them to levels of ultraviolet radiation equivalent to sunlight on the red planet, which is cooler than Earth. The team, from the University of Edinburgh, the Max Planck Institute in Germany and Utrecht University, found that the amount of methane given off by the particles was significant, and could account for a large part of the methane in Mars\' atmosphere. Dr Andrew McLeod, of the University of Edinburgh\'s School of GeoSciences, said: \"Whether or not Mars is able to sustain life is not yet known, but future studies should take into account the role of sunlight and debris from meteorites in shaping the planet\'s atmosphere.\" What the findings do suggest is that the presence of methane isn\'t enough to say that life exists on Mars.