A patch of land in an ancient valley on Mars may once have been home to salty groundwater – and, it could now be a prime target in the search for past life.
Researchers discovered an area that appears to have been flooded by water, with a number of flowing striations in sand dunes that resemble those in the Namib Desert here on Earth.
The team suspects the Martian area may have undergone a similar process as in Namibia, with evidence that there may have been active water near the equator in the not-too-distant past.
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A patch of land in an ancient valley on Mars may once have been home to salty groundwater Researchers discovered an area that appears to have been flooded by water, with a number of flowing striations in sand dunes that resemble those in the Namib Desert here on Earth
In the study, researchers form Trinity College Dublin investigated ‘arcuate striations’ on the Martian surface.
Previous work in a remote sensing study of the Namib Desert identified these features on the surface between migrating dunes.
Further analysis revealed that the striations were the result of dune sediments that had been geochemically cemented by the salts left behind by evaporating groundwater.
Eventually, the dune sediments became immobile, and were left behind as the dunes migrated downwind.
‘On Earth, desert dunefields are periodically flooded by water in areas of fluctuating groundwater, and where lakes, rivers, and coasts are found in proximity,’ said Dr Mary Bourke.
‘These periodic floods leave tell-tale patterns behind them.
‘You can imagine our excitement when we scanned satellite images of an area on Mars and saw this same patterned calling card, suggesting that water had been present in the relatively recent past.’
Previous work in a remote sensing study of the Namib Desert identified these features on the surface between migrating dunes. The striations were the result of dune sediments that had been geochemically cemented by the salts left behind by evaporating groundwater
According to the researchers, the observations of Mars suggest a similar process could be at play.
And, not only would this mean Mars had water in the recent past, but it could also indicate that the location may once have hosted life.
‘Following our work in Namibia, we hypothesize that on Mars, similar arcuate striations exposed on the surface between dunes are also indications of fluctuating levels of salty groundwater, during a time when dunes were actively migrating down the valley,’ Dr Bourke said.
Evidence of water on Mars dates back to the Mariner 9 mission, which arrived in 1971. It revealed clues of water erosion in river beds and canyons as well as weather fronts and fogs.
Viking orbiters that followed caused a revolution in our ideas about water on Mars by showing how floods broke through dams and carved deep valleys.
Mars is currently in the middle of an ice age, and before this study, scientists believed liquid water could not exist on its surface.
In June 2013, Curiosity found powerful evidence that water good enough to drink once flowed on Mars.
In September of the same year, the first scoop of soil analysed by Curiosity revealed that fine materials on the surface of the planet contain two per cent water by weight.
Last month, scientists provided the best estimates for water on Mars, claiming it once had more liquid H2) than the Arctic Ocean – and the planet kept these oceans for more than 1.5 billion years.
The findings suggest there was ample time and water for life on Mars to thrive, but over the last 3.7 billion years the red planet has lost 87 per cent of its water – leaving it barren and dry.
‘These findings are hugely significant. Firstly, the Martian sand dunes show evidence that water may have been active near Mars’ equator – potentially in the not-too-distant past.
‘And secondly, this location is now a potential geological target for detecting past life forms on the Red Planet, which is important to those involved in selecting sites for future missions.’
The find comes as NASA revealed it’s finally selected three potential target sites for its Mars 2020 mission: the Jezero crater, Northeast Syrtis, and Columbia Hills.
A robot rover will scan the surface of the chosen landing site before taking detailed pictures and collecting rocky samples to bring back to Earth.