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A huge 19 km wide liquid water lake lies beneath the southern ice cap from Mars, scientists have learned.
Dissolved salts are believed to maintain fluid water despite a temperature below freezing.
The discovery, which has major implications for the chances of survival of the red planet, was made by a European probe in orbit. radar penetrating the ground.
This is the first time that a large volume of stable liquid water exists on Mars.
The lake, similar to those under the ice sheets of Antarctica and Greenland, lies about 1.5 kilometers below the surface of an area called Planum Austral, near from the south pole of Mars, and stretches for 20 kilometers. With surface temperatures as low as 68 ° C, it would not exist as a liquid under normal conditions.
But the dissolved salts of magnesium, calcium and sodium – known to be present in Martian rocks – are believed to maintain the brackish miniature sea by reducing the melting point of water to minus 74 ° C.
An Italian team of scientists detected the lake by conducting a radar survey using the Mars Express probe
Between 2012 and December 2015 the Planum Austral region was mapped by the Mars Advance radar for the Subsurface and ionosphere (Marsis) survey instrument carried on the orbiter.
Radio waves emitted at the surface by Marsis penetrated through the ice and bounced towards the surface. pacecraft
Far beneath the ice cap at the south pole of Mars is a lake of liquid water – the first on the red planet: https://t.co/VBue3BcEgn
– News of science ( @NewsfromScience July 25, 2018
Of the 29 radar samples, scientists spotted a series of unusually strong reflections with a distinct electrical mark, revealing the presence of liquid water
Professor Roberto Orosei, from the University of Bologna, wrote in the journal Science: "Abnormally bright subterranean reflections are evident in a well-defined area 20 kilometers wide .. which is surrounded by much less reflective zones. [19659004] "The quantitative badysis of radar signals shows that this luminous characteristic has a high relative dielectric permittivity (electrical polarization) corresponding to that of aquiferous materials.
" We interpret this characteristic as a stable body. liquid water on Mars.
Whatever the case may be, the discovery greatly increases the extraterrestrial chances
The liquid water is an essential condition of life as we know it
There are billions of years, it is thought that Mars had oceans and rivers, a little like the Earth, primitive life may have evolved on the planet and then be extinguished when the world lost most of its atmosphere and became an arid icy desert.
If large expanses of liquid water lie beneath the Martian polar ice, they could theoretically
High levels of salt in the water could make the environment difficult, but not impossible for life.
On Earth, a group of organisms known as "halophiles" thrive in very salty conditions like those In an interview recorded by Science, Professor Orosei revealed that his team has spent years checking their results before being confident enough to announce the discovery.
"We found that any other explanation for these very strong echoes was not really tenable in light of the evidence we had available," he said. "We had to conclude that there is water on Mars today."
Radar data showed that the lake contained a large amount of salt, added Professor Orosei
"This is certainly not a very nice environment for life." He said.
But he pointed out that similar salty subglacial lakes in Antarctica had been found to support life.
"There are unicellular organisms that survive in such an environment with a metabolism that uses salt.", Said Professor
Marsis was not able to measure the depth of the lake, but scientists believe that it must be at least one meter thick.
Press Association
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