Clues to life on Mars have been found in the Chilean desert

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A NASA rover equipped with a drill has collected micro organisms from three feet underground in Chile’s Atacama desert, a study claims.

It is hoped that the experiment will give scientists a clearer picture of what kind of bacteria they might expect to get from the arid soil on Mars.  

They use the Atacama desert as a testing ground because it is the most ‘Mars-like’ region on Earth and will accurately replicate the harsh, irradiated environment.

The robotic rover collected micro-organisms from the subsurface soil ahead of NASA and European Space Agency missions to the Red Planet in 2020. 

The microbes they found had adapted to high salt levels, similar to what may be expected in the Martian subsurface.   

Because of its high UV radiation exposure and very salty soil, the desert is the closest match and therefore the best place for simulating missions to this planet.

Study leader Professor Stephen Pointing, of Yale-NUS College, Singapore, said: ‘We have shown that a robotic rover can recover subsurface soil in the most Mars-like desert on Earth.

‘This is important because most scientists agree that any life on Mars would have to occur below the surface to escape the harsh surface conditions where high radiation, low temperature and lack of water make life unlikely.

‘We found microbes adapted to high salt levels, similar to what may be expected in the Martian subsurface. 

These microbes are very different from those previously known to occur on the surface of deserts.

The autonomous solar-powered rover travelled 31 miles (50 km) over two types of terrain similar the surface of Mars. 

One was stony desert pavement, and the other was sandy and typical of the desert environment.   

The samples recovered by the autonomous rover contained unusual and highly specialised microbes that were distributed in patches.

Researchers then linked their dispersal to limited water availability, scarce nutrients and chemistry of the soil.

The drill used in the study had a depth of 31.5 inches (80cm) and its samples were compared to those recovered by hand. 

In the coming years rovers will be deployed to Mars to drill below the ground to find evidence of past or present life. 

Mars missions hope to drill to approximately 2m and so having an Earth-based comparison will help identify potential problems and the interpretation of results.

‘Ecological studies that help us predict the habitable areas for microbial communities in Earth’s most extreme environments will also be critical to finding life on other planets,’ said Professor Pointing.    

DNA sequencing found the results of each methods were similar and that the trial was a success.

Professor Pointing said future research includes drilling deeper to understand just how far down recoverable microbes occur.

The tests also revealed that microbial life was very patchy and related to the limited water availability, scarce nutrients and geochemistry of the soil.

Study co-author Dr Nathalie Cabrol, of The SETI Institute, said: ‘These results confirm a basic ecological rule that microbial life is patchy in Earth’s most extreme habitats, which hints that past or present life on other planets may also exhibit patchiness.’

She added: ‘While this will make detection more challenging, our findings provide possible signposts to guide the exploration for life on Mars, demonstrating that it is possible to detect life with smart robotic search and sampling strategies.’

The findings of the study were published in the journal Frontiers in Microbiology.

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