Scientists are eager to find signs of contemporary water, because such discoveries are key to unlocking the mystery of whether life ever formed on Mars in its ancient past, or if it might persist today. Using ice-penetrating radar from orbit, researchers from the Italian Space Agency reportedly found a lake deep beneath the Red Planet's polar ice caps. Some deposits have been mapped by the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS), an instrument on the European Space Agency's Mars Express orbiter, which launched in 2003.
Water is essential to life as we know it, and scientists have long sought to prove that the liquid is present on Mars. Conveniently, there's another radar instrument called SHARAD orbiting the Red Planet on the Mars Reconnaissance Orbiter.
Twenty-nine observations were made between 2012 and 2015 in the Planum Australe region at the south pole using the MARSIS radar on ESA's Mars Express spacecraft. The presence of the underground lake was discovered by scientists at the Italian National Institute for Astrophysics (INAF), in Rome, DailyMail cited.
This discovery of a salty subsurface lake, on an object much closer to the Sun, and much larger than a moon, is even bigger news.
The next step is for space authorities to definitively confirm the body of water is there - and then the search for life begins.
For example, they considered that there could be a carbon dioxide or water ice layer within the zone that could affect the reflections, but this was rejected "because of the very specific and unlikely physical conditions required, or because they do not cause sufficiently strong basal reflections", the researchers wrote Science paper stated.
Almost 4.5 billion years ago, Mars had six and a half times as much water as it does now and a thicker atmosphere. On Mars, "polar materials" actually extend hundreds of kilometres toward the equator along the 150° east longitude, says NASA.More news: European Union officials to meet Trump, wielding a $20-billion threat
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"This thrilling discovery is a highlight for planetary science and will contribute to our understanding of the evolution of Mars, the history of water on our neighbour planet and its habitability", said Dmitri Titov, ESA's Mars Express project scientist.
Researchers said they are not sure how far down it goes, but may be around one meter (three feet) deep.
This, however, is the best evidence to date of an environment on Mars that could be friendly to known forms of life - these "extremophile" bacteria - right now.
The publication states that the find is so large that it resembles subglacial lakes on Earth.
Jeffrey Plaut of NASA's Jet Propulsion Laboratory said in an email that the interpretation that it is liquid water is "certainly plausible, but it's not quite a slam dunk yet". Their first source of water is more likely to be the ice sheets that have been found just below the surface at various spots around the planet's midsection. Orbiters have also revealed enormous glaciers residing just under the surface, potentially accessible to any future explorers or even colonists that go there in the future.
Bramson said the Mars radar community remained curious about why SHARAD didn't detect water below the south pole.