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A vast underground lake was discovered for the first time on Mars, where ever such a volume of liquid water, a prerequisite for the development of life, had yet been found, an international team announced on Wednesday. astronomers.
Located under a layer of Martian ice, the lake is about 20 km wide and suggests the presence of more water, even life, on the red planet, according to an article published in the American journal Science
"There is water there, there is no doubt about it," one of the co-authors of the study, Enrico Flamini, responsible for the mission, told a press conference. Mars Express of the Italian Space Agency
The planet Mars is now cold, desert and arid, but was previously hot and humid and sheltered a large quantity of liquid water and lakes there are at least 3, 6 billion years.
Scientists are looking to find These are contemporary traces of liquid water, such discoveries being essential to unravel the mystery of a possible form of life on Mars in the distant past, or even its persistence to the present day.
Being able to access to water sources could also help humans survive in future exploration missions to the nearby red planet.
The lake water that has just been discovered may, however, not be drinking. It is also 1.5 km below the surface, in a harsh and icy environment.
– "Staying cautious" –
The presence of a possible form of microbial life in the lake is Subject to debate
Some experts are skeptical on this point, believing that the lake is too cold and brackish and contains a high dose of dissolved Martian salts and minerals.
The temperature is probably below the point freezing of pure water, but the lake can remain in the liquid state due to the presence of magnesium, calcium and sodium.
"This is a discovery of extraordinary significance, which may strengthen the badumptions about the presence of living organisms on the red planet, "said Fred Watson of the Australian Astronomical Observatory, which was not involved in the study.
" However, we must remain cautious because the concentration of salts needed to maintain the water at the liquid state could be fatal to any microbial life similar to that on Earth, "he adds.
The discovery was made using a radar instrument aboard the Mars Express spacecraft of the European Space Agency, launched in 2003.
Called Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS ), the device was designed to find groundwater by sending radar waves across the surface and ice cap.
MARSIS "then measures how the waves propagate and return to the probe "explains the study, conducted by Italian researchers under the direction of Roberto Orosei, of the Istituto Nazionale di Astrofisica in Bologna.
The latter surveyed between May 2012 and December 2015 a region called Planum Austral, located under the southern ice cap of Mars.
A total of 29 series of radar samplings showed "a sharp change from the badociated radar signal", which allowed scientists to grasp the contours of the lake.
"The radar profile of this area is similar to the lakes of liquid water found beneath the ice sheets of Antarctica and Greenland on Earth, suggesting that there is a subglacial lake at this location on Mars, "the study details. [19659002] Astronomers say they are not sure about the depth of the lake, but estimate it to be about one meter
– Another helpless radar –
SHARAD, a higher frequency radar, designed by the Agency Italian spacecraft and embarked on the Mars Reconnaissance Orbiter probe, launched in 2005, was not able to detect the presence of the underground water lake.
"It is strange that SHARAD can not confirm this discovery, "wonders, in an email to AFP, D Avid Stillman, researcher at the Department of Space Studies, Southwest Research Institute, Texas.
"SHARAD can not penetrate the ice here and no one understands why," the American scientist continues, "skeptical about this discovery."
But researchers are hopeful that news: if the presence of liquid water could be detected under the south pole of Mars, it might be possible to find elsewhere.
"This area has nothing special, except that the radar MARSIS is more sensitive to this place, which means that it is likely that similar bodies of water exist beneath the surface all around Mars, "says Alan Duffy, badociate professor at Swinburne University, Australia. ]
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