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Liquid water 'lake' revealed on Mars

[img]https://ichef.bbci.co.uk/news/320/cpsprodpb/1868/production/_102684260_marsbg.jpg" width="976" height="549">
Researchers have found evidence of an existing body of liquid water on Mars.The proposed "lake" sits beneath the Red Planet's south polar ice cap, and is about 20km across.Previous research found possible signs of intermittent liquid water flowing on the martian surface, but this is the first sign of a persistent body of water on the planet in the present day.Lake beds like those explored by Nasa's Curiosity rover show water was present on the surface of Mars in the past.However, the planet's climate has since cooled due to its thin atmosphere, leaving most of its water locked up in ice.
The discovery was made using Marsis, a radar instrument on board the Mars Express orbiter.
The proposed lake sits beneath ice near the south pole of Mars
"It's probably not a very large lake," says Prof Roberto Orosei from the Italian National Institute for Astrophysics, who led the study.Marsis wasn't able to determine how deep the layer of water might be, but the research team estimate that it is a minimum of one metre."This really qualifies this as a body of water. A lake, not some kind of meltwater filling some space between rock and ice, as happens in certain glaciers on Earth," Prof Orosei added.
Artists impression: Mars Express probing the planet's surface. Marsis radar results above.
How was it found[/img]

Artists impression: Marsis data shows an area of high reflectivity (dark blue) which is thought to be water
What does this mean for life?
Nothing definitive. Yet.Dr Manish Patel from the Open University explains: "We have long since known that the surface of Mars is inhospitable to life as we know it, so the search for life on Mars is now in the subsurface.
"This is where we get sufficient protection from harmful radiation, and the pressure and temperature rise to more favourable levels. Most importantly, this allows liquid water, essential for life."This principle of following the water is key to astrobiology - the study of potential life beyond Earth.So while the findings suggest water is present, they don't confirm anything further."We are not closer to actually detecting life," Dr Patel told BBC News, "but what this finding does is give us the location of where to look on Mars. It is like a treasure map - except in this case, there will be lots of 'X's marking the spots."
Astrobiologists study extreme environments like salt lakes on Earth to understand how life might survive on Mars
The water's temperature and chemistry could also pose a problem for any potential martian organisms. In order to remain liquid in such cold conditions (the research team estimate between -10 and -30 Celsius where it meets the ice above), the water likely has a great many salts dissolved in it."It's plausible that the water may be an extremely cold, concentrated brine, which would be pretty challenging for life," explained Dr Claire Cousins, an astrobiologist from the University of St Andrews, UK.
What next?
While its existence provides a tantalising prospect for those interested in the possibility of past or present life on Mars, the lake's characteristics must first be verified by further research."What needs to be done now," explained Dr Matt Balme from the Open University, "is for the measurements to be repeated elsewhere to look for similar signals, and, if possible, for all other explanation to be examined and - hopefully - ruled out. "Maybe this could even be the trigger for an ambitious new Mars mission to drill into this buried water-pocket - like has been done for sub-glacial lakes in Antarctica on Earth," he added.
The area has been compared to Lake Vostok, which lies 4km beneath the Antarctic ice
Scientists have previously claimed to find bacterial life in the buried depths of Antarctica's Lake Vostok, but drilling on Mars would make for an ambitious project indeed."Getting there and acquiring the final evidence that this is indeed a lake will not be an easy task," says Prof Orosei. "It will require flying a robot there which is capable of drilling through 1.5km of ice. This will certainly require some technological developments that at the moment are not available,"Follow Mary on Twitter.
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