A team of European planetary scientists has found direct evidence of melting and significant flows of liquid water beneath a degraded glacier in the southern Phlegra Montes region of Mars.
Oblique view of the Phlegra Montes region showing remnant glacier and eskers. Image credit: NASA.
Dr Matthew Balme of Open University, UK, and Dr Colman Gallagher of University College Dublin examined a landform known as an ‘esker’, emerging from a Late Amazonian-aged (150 million years ago) glacier in Phlegra Montes.
Eskers are ridges of sediment similar to a dried-out river bed, which form only by sustained flows of liquid water underneath a glacier. They are found only in ‘wet-based’ glacial systems – but glaciers on Mars have generally been thought to be ‘dry-based’ with no melt water.
“Finding an esker on Mars means that significant quantities of liquid water flowed beneath this glacier, and that liquid water can persist in the near-surface environment, despite Mars being generally too cold to permit liquid water,” explained Dr Gallagher, who is a co-author of a paper published online in the journal Earth and Planetary Science Letters.
Despite a number of similarities between the climate of Mars and that on Earth, the presence of liquid water has remained one of the key differences between the two planets and an important factor in determining whether the planet could sustain life.
Indirect evidence for eskers on the Red Planet has been reported before, but the new study offers the first observation of eskers directly linked to a glacier.
“Eskers have been reported on Mars before, but they are normally stranded in the landscape with little to associate them with a glacial system,” Dr Balme said.
“This is the first identification of an esker system on Mars that is still physically associated with its parent glacier.”
“Eskers on Mars are important as they indicate melt of glacial ice – and finding another type of environment where liquid water can occur is important in the whole ‘life on Mars’ question, as it provides yet more evidence for habitability in the recent past,” Dr Balme said.
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Colman Gallagher & Matthew Balme. 2015. Eskers in a complete, wet-based glacial system in the Phlegra Montes region, Mars. Earth and Planetary Science Letters, vol. 431, pp. 96-109; doi: 10.1016/j.epsl.2015.09.023
