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Never before had such a volume of liquid water been found on Mars. A vast underground lake was discovered for the first time on Mars, an international team of astronomers announced on Wednesday. Located under a layer of Martian ice, the lake has a width of about 20 km and suggests the presence of more water, even life, according to an article published in the American journal Science . "There is water there. This is no longer a doubt, "said one of the co-authors of the study, Enrico Flamini, head of the Mars Express mission of the Italian Space Agency.
The planet Mars is today cold, desert and arid, but was previously hot and humid and was home to a large amount of liquid water and lakes at least 3.6 billion years ago. Scientists seek to find contemporary traces of liquid water, such discoveries being essential to unlock 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 water sources could also help humans survive in future exploration missions to the nearby red planet Earth. The lake water that has just been discovered may not be drinkable, however. It is 1.5 km below the surface in a harsh and icy environment.
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Discovery "of extraordinary significance"
The presence of a possible microbial life form within the lake is subject to debate. Some experts are skeptical about this, saying the lake is too cold and brackish and contains a high dose of dissolved salts and minerals. The temperature is probably below the freezing point 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 that can reinforce the badumptions about the presence of living organisms on the red planet," said Fred Watson of the Australian Astronomical Observatory, who did not participate in the event. 'study. "However, we must remain cautious, because the concentration of salts needed to maintain water in 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 aircraft was designed to find groundwater by sending radar waves across the surface and the icecap. 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. Between May 2012 and December 2015, they surveyed a region called Planum Austral, located under the southern ice cap of Mars.
In total, 29 series of radar samplings showed a "sudden variation compared to the badociated radar signal" , which allowed scientists to understand the contours of the lake. "The radar profile of this area is similar to that of the liquid-water lakes found beneath the ice sheets of Antarctica and Greenland on Earth, suggesting that there is a subglacial lake at this location on Mars" , details the study. 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 Space Agency Italian and embarked on the Mars Reconnaissance Orbiter spacecraft, launched in 2005, has not been able to detect the presence of the underground water lake. "It is strange that SHARAD can not confirm this discovery," David Stillman, a researcher at the Department of Space Studies, Southwest Research Institute, Texas, asked in an email to Agence France-Presse. "SHARAD can not actually penetrate the ice here and no one understands why," the American scientist continues, "skeptical about this discovery."
But researchers are hopeful of making new ones: 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 MARSIS radar is more sensitive to this area. This 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). Canadian astronaut Chris Hadfield shared this thought on Twitter: "On Earth, where there is water, there is life. We may not be alone. "
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