Mars' 'little green men' buried alive by merciless meteorites – new theory

Organic compounds unlikely to have survived cosmic pummeling, say scientists

Mars impact

Scientists hoping to find signs of Martian life on the surface of the Red Planet may not be in luck.

Any evidence of life could have been destroyed in a meteor impact, according to research published in Scientific Reports, an online open access scientific mega journal published by the Nature Publishing Group.

Samples analyzed from the surface of Mars have not yielded any conclusive evidence of organic compounds from ancient life forms. Scientists think that the search might be more fruitful if they were to go beneath the surface.

The idea is that any rocks containing organic compounds that were buried underground through meteorite collisions are more likely to survive, as they are shielded from the harmful effects of solar radiation and other chemical processes.

However, a team of researchers from Imperial College London and the University of Edinburgh have found that the search for life may prove more difficult.

The effects of meteorite blasts the size of ten metres were replicated by generating high pressures and temperatures using a piston cylinder device. A chemical analysis to find the level of organic matter was performed using pyrolysis-gas chromatography mass-spectrometry.

Researchers found that the long chains of hydrocarbon-dominated matter often found in microbial or algal life were destroyed upon collisions. But aromatic hydrocarbon dominated matter – often found in plant matter – was more likely to survive.

Chemical reactions caused the aromatic hydrocarbons to change, but they were more resistant to high pressure conditions.

Professor Mark Sephton, co-author of the research from the Department of Earth Science and Engineering at Imperial College London, said: "Our study is showing us that we may need to be nuanced in our approach to the rocks we choose to analyse."

Two years ago, NASA's Curiosity Rover detected organic compounds containing chlorine – including chlorobenzene and several dichloroalkanes such as dichloroethane, dichloropropane and dichlorobutane – by drilling beneath the Gale crater. It is difficult, however, to determine the origin of the simple chlorine-containing organic compound components and the results do not prove Martian life once existed.

To help narrow the search for Martian life further, the researchers hope to continue testing out meteorite collisions over a broader range of pressures and temperatures to find the specific conditions needed for organic matter to survive blasts. ®

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