This principle of following the water is key to astrobiology - the study of potential life beyond Earth. However, previous research has unearthed what appear to be ancient seabeds and river valley networks that show Mars was once covered in rivers, streams, ponds, lakes, and perhaps even seas and oceans.
"It is liquid, and it's salty, and it's in contact with rocks", he added.
Bramson said the Mars radar community remained curious about why SHARAD didn't detect water below the south pole. The subsurface lake, Diez says, may be similar those found via radar-sounding on Earth beneath ice sheets in Antarctica and Greenland. Still, that might not prevent life from calling the lake home.
These days, it's only about 20 percent - like we said at the top, conditions on Mars are not forgiving.
"This is potentially the first habitat we know of on Mars".
Since humans could see through telescopes across space, Mars has been the favorite abode of imaginary life, the backyard just over the fence where astronomer Percival Lowell imagined he could see canals and even cities webbing the orange globe.
It has always been suspected that the Red Planet is not as dry and arid as it looks.
First lake of liquid water is discovered on Mars
Michael Meyer believes the more we study Mars, the more we will learn how life could be supported and where there are resources to support life in the future. The surface is scored by old gorges, canyons, beaches, ocean basins and giant volcanoes, whose eruptions could have kept things riled up on the planet.
Located at the edge of a more than three-billion-year-old ice cap covering Mars's south pole, the region known as Planum Australe would rank high on any list of the Red Planet's least-interesting locales. "We've been finding life in places it shouldn't be according to our current thinking of life". If astronauts ever crunch across the red sands will they also be crunching over fossils of microbes? However, "SHARAD uses higher-frequency radio waves that cannot penetrate as deep as MARSIS can", Pettinelli says.
The discovery was made using radar instruments from the Mars Express probe of the European Space Agency (AEA), launched in 2003. Taking care not to damage the rest of the spacecraft, the team in charge of MARSIS took two years to deploy the radar's 130-foot-long booms. The intensity of brightness also reveals what the substance is that reflects the radar back; salt water is bright. Intense pressure of the overlying ice would warm the ice.
Computer models indicate that temperatures would be about minus 67 degrees Celsius - far colder than the melting point of water. "If that were to be liquid water, it would be only feasible if there will be large concentrations of salts within it".
"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". A satellite broadcasts radar signals to the surface.
Such radars are useful when searching for liquid water, "because water is a very strong radar reflector", he says.
For some scientists, the bright radar reflection falls a bit short of proof.
"The estimated temperature, which is to be debated to some degree, at the depth at which this water is occurring is said to be 205 K [90˚ F]", said Vlada Stamenković, a research scientist at NASA's Jet Propulsion Laboratory. This water is not exactly hospitable - "it's basically got antifreeze in it", says Andrew Coates, a professor of space physics at University College London who has worked on several space missions.
British Foreign Secretary Hunt Warns Of No-Deal Brexit Risk
In an interview with Channel 5 News on Wednesday, May rejected the suggestion voters should be anxious . The risks of not reaching a Brexit deal were underlined by Cabinet ministers on Tuesday.