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Astronomers have found compelling evidence that there is a huge reservoir of liquid water buried under ice near the South Pole on Mars.
Radar measurements taken by the Mars Express orbiter of the European Space Agency spotted the 12 miles wide. stretch of water at the base of a thick layer of polar ice in an area known as Planum Austral.
This is the first time that researchers have identified a stable body of liquid water on the red planet. The discovery raises the possibility that any microbial life on Mars can continue to survive a rather dark existence beneath the surface.
"We discovered water on Mars," said Roberto Orosei at the National Institute of Astrophysics in Bologna. Any other explanation for the brilliant reflections that scientists saw in their radar observations was "untenable," he added. The details of the discovery are reported in the journal, Science
Today, the most obvious signs that Mars was once a wet world are the ancient streams that have carved the surface of the planet there are many millions of years. In 2015, NASA announced it had seen water infiltrating the slopes and gullies on the planet, but this interpretation was questioned last year when US Geological researchers Survey claimed that the mysterious dark trails were only grains. explains how water was found on Mars – video
For the latest discovery, Italian researchers analyzed three years of data collected by an instrument called Mars Advanced Radar for underground and ionospheric sounding, or Marsis, aboard the Mars Express probe. The measurements, collected between 2012 and 2015, show that radar waves penetrated the clear ice at the south pole of Martian, but strongly reflected on a water plane below.
John Bridges, professor of global science at the University of Leicester, who helped locate the last resting place of the British Beagle 2 lander on Mars, said the scientists had made a case convincing for liquid water on Mars. "This is a careful analysis of the data." Elena Pettinelli, a scientist from the Roma Tre University team, said that it was impossible to know whether the plan for the project was a "one-stop-shop". water was a lake or aquifer where water was interconnected, pores in the Martian rock.If it is an open water plan, it may resemble Lake Vostok, the largest subglacial lake in the world. Antarctica, she said.
Scientists also can not tell the depth of the water. The radar pulses of the Marsis instrument bounce off the water but Do not reach the bottom of the tank.The best that scientists can say is that the water is at least a meter or two.
What they know, is that the water is extremely cold.In the bottom of the ice at the south pole of Mars, the temperature is estimated at about -68 C. Although very much less than zero, the water is supposed to remain liquid because It is under pressure and rich in salts, especially magnesium, calcium and sodium compounds known as perchlorates, easily present on the surface of Mars.
Although it is hardly ideal for life as we know it, brackish liquid could potentially support microbes that have adapted to such salty conditions. The challenge that all Martian microbes would face is to resist the osmotic potential that acts to draw water into the cells and leave them in a dried up pile. "It's certainly not a very nice environment for life," Orosei said. Although not being an expert in the extreme extremes that life can bear, Bridges suspects that salty conditions in Martian water could be too much to survive. "I think it's really, really stretching the envelope of potential life to breaking point," he said.
Mark Sephton, who studies life in extreme environments at Imperial College London, said: Mars was not in itself a problem for life. The surface of Mars is bombarded by intense radiation that effectively sterilizes the surface, so if life is hiding anywhere on the planet, it is likely to be underground. "As long as there is a source of energy to exploit and a source of nutrients or raw materials, life is possible," he said.
"Saline conditions are good for maintaining a liquid state.If salt concentrations outside the cell are higher than inside, it extracts water from the inside of the cell and the cell retracts and dries out.Life can adapt by synthesizing organic molecules to stop the process, but there are limits, beyond which high salinities in the cell interfere with biochemistry and the matrix dies, "added Sephton." So for Mars, some mechanisms that keep water in a liquid state can work at levels that are too good for life. "[19659002] It may take some time for scientists to study the water under the South Pole to see if life is hiding there. "Arrive there and gain the ultimate proof that it actually a lake will not be an easy task, "said Orosei. will be able to drive a robot capable of drilling through 1.5km of ice and this will certainly require technological developments that are not available for the moment. "
For now, researchers will look for Other sites on Mars for signs of lakes or more subterranean aquifers. When writing in the newspaper, the authors say, "There is no reason to conclude that the presence of underground water on Mars is limited to one place."
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