A team of Italian researchers have poked at the polar ice caps on Mars with a radar and uncovered a lake that stretches about 20km across and 1.5km deep.
Still, the more measurements scientists can collect, the more confident they can be.
"This lake, if it really is there, would be a prime place to look for life - after all, we have similar things on Earth, like the lakes buried beneath Antarctica, and life has been found to exist and thrive down there".
Detection via radar signals means that the thickness "would need to be at least several tens of centimeters thick", according to a statement by the European Space Agency, which described the body of liquid water as "possibly laden with salty, saturated sediments".
There have been previous signs of liquid and water activity on Martian slopes, but never before a "stable body" - which strengthens the notion of alien life inhabiting the planet.
"We are fairly certain that there is liquid water below the surface". Experts believe this raises the possibility of finding life on the red planet.
The device that can be credited for the new discovery of the liquid lake on the red planet is called the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument (MARSIS) and was held on the orbiter known as the Mars Express, which was deployed by the European Space Agency.
Mars is very cold, but the water might have been kept from freezing by dissolved salts.
Radio waves beamed down to the surface by Marsis penetrated through the ice and bounced back to the spacecraft.
Professor Dempster said Australia had taken a leadership position on the matter, with University of New South Wales researchers examining business cases, mining methods, earth analogues, asteroid selection, asteroid navigation and other resources such as platinum.
These reflections "provide scientists with information about what lies beneath the surface".
Researchers said they are not sure how far down it goes, but that it may be around three feet (one meter) deep. Orosei is with Italy's National Institute of Astrophysics, The Associated Press reported.
"This is the first body of water it has detected, so it is very exciting", David Stillman, a senior research scientist in the Department of Space Studies at Southwest Research Institute in San Antonio, Texas, told AFP in an email. "This would confirm that IF it is true", Kral said.
He noted that a higher-frequency radar instrument made by the Italian space agency SHARAD, on board the MarsReconnaissance Orbiter launched in 2005, has been unable to detect subsurface water. "Thus, I'm sceptical about this discovery".
Layered deposits at the south pole of Mars.
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