CURIOSITY FINDS METHANE AND ORGANIC COMPOUNDS ON MARS
Mars Curiosity rover has detected methane on Mars, and has also found organic compounds in rock samples., hints of past or present life on Mars:
The source of the methane cannot be identified. Curiosity scientist Professor Sushil Atreya of the University of Michigan said 'It's possible that clathrates are involved. These are molecular cages of water-ice in which the methane gas is trapped. From time to time, these could be destabilised, perhaps by some mechanical or thermal stress, and the methane gas would be released to find its way up through cracks or fissures in the rock to enter the atmosphere.'
The methane could have got into the clathrate stores from Martian bugs, but it could also have come from a natural process which produces methane when water interacts with certain types of rocks. One way to investigate whether the Martian methane has a biological or geological origin would be to study the ratio of carbon-12 to carbon-13 in the gas, and compare it to figures on Earth. A high ratio would indicate a biological origin. The methane volumes found so far on Mars are insufficient for this type of experiment.
The methane detection by Curiosity confirms the presence of methane that is also observed by orbiting spacecraft at Mars, and by telescopes on Earth, but which earlier could not be found by Curiosity.
Curiosity has also detected organic compounds, chlorobenzene, in the rocks it has been drilling. This is the first detection of organics in surface materials on Mars. It's not certain whether the organic material was actually present in the original rock, or was a produced during the analysis heating process.
Comment: The importance of these findings is that life as we know it can only exist in the presence of complex carbon structures. We may still be far from proving that life existed on Mars, but these are significant steps in the right direction.