London: Scientists have discovered a patch of land in an ancient valley on Mars that may have been flooded by water in the not-too-distant past and could serve as the prime target to begin searching for evidence of life forms on the red planet.
“On Earth, desert dune fields are periodically flooded by water in areas of fluctuating groundwater, and where lakes, rivers and coasts are found in proximity. These periodic floods leave tell-tale patterns behind them,” said Mary Bourke from Trinity College Dublin in the UK.
“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,” said Bourke.
In a remote sensing study of the Namib Desert, researchers including Heather Viles, from the University of Oxford in the UK had noted these patterns – ‘arcuate striations’ – on the surface between migrating sand dunes.
Fieldwork subsequently showed that these arcuate striations resulted from dune sediments that had been geochemically cemented by salts left behind by evaporating groundwater. These dune sediments later become relatively immobile, which means they are left behind as the dunes continue to migrate downwind.
“Following our work in Namibia, we hypothesise 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,” Bourke said.
“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,” she said. “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,” she added. The research was published in the journal Geophysical Research Letters.