Massive Lake Of Liquid Water Detected Under Mars' Surface

If researchers are correct, this is the first time a large body of liquid water has been found on our neighbouring planet.

In what is potentially the greatest development in recent Mars exploration, scientists believe they have found evidence of a giant lake of liquid water buried beneath the planet's south pole.

The Italian Space Agency announced on Wednesday the discovery of a 20-kilometre-wide body of liquid water locked 1.5 kilometres beneath the frozen  Martian surface.

If confirmed by future observations, the Italian team's findings published in this week's issue of Science will have significant implications for chances of finding life on the red planet.

"This is a stunning result that suggests water on Mars is not a temporary trickle like previous discoveries but a persistent body of water that provides the conditions for life for extended periods of time," Swinburne University astronomer Associate Professor Alan Duffy said.

An artistic rendering shows the Mars Express Spacecraft proving Mars' south pole. Image: Davide Coero Borga/ESA/INAF

The water has likely remained in liquid form due to huge amounts of dissolved salts which have kept the lake from freezing in the minus 68 degree temperatures of the pole.

Water is crucial to life as we know it.

Theoretically, its presence beneath Mars' polar ice could mean the planet harbours living microbes, potentially similar to the species of fungi and bacteria scientists have found signs of four kilometres beneath Lake Vostok in Antarctica. 

"This is a discovery of extraordinary significance, and is bound to heighten speculation about the presence of living organisms on the red planet," Australian Astronomical Observatory Professor Fred Watson said.

"Caution needs to be exercised, however, as the concentration of salts needed to keep the water liquid could be fatal for any microbial life similar to Earth’s."

The discovery was made using a ground-penetrating radar aboard the European Space Agency's Mars Express spacecraft, an orbiting probe which has been studying the red planet since 2003.

The strong radar echoes believed to be liquid water are shown here in deep blue. Image: USGS Astrogeology Science Centre, Arizona State University, INAF. Image: USGS Astrogeology Science Centre, Arizona State University, INAF.

The MARSIS radar instrument beams pulses of radio waves down to the surface and examines what is bounced back. While the waves pass through rock and ice, they bounce back if they hit water.

The radar profile of a patch of ice called Planum Australe on Mars' south pole was found to be similar to sub-glacial lakes found on our own planet beneath the Antarctic and Greendland ice sheets, researchers said.

"Anomalously bright subsurface reflections are evident within a well-defined 20km-wide zone, which is surrounded by much less reflective areas," Professor Roberto Orosei, from the University of Bologna, wrote in the journal Science.

"Quantitative analysis of the radar signals shows that this bright feature has high relative dielectric permittivity (electrical polarisation) matching that of water-bearing materials. We interpret this feature as a stable body of liquid water on Mars."

But while the findings have many excited, the interpretation of the radar's data will undergo intense scrutiny from the scientific community before any hard and fast conclusions can be made.

Scientists have long searched for evidence of present-day liquid water on Mars but have previously only yielded empty or ambiguous results.

In 2015, NASA announced evidence of liquid water flowing across Mars' dunes, only to find two years later it was most likely sand.

But for now, Orosei says the next step on Mars is to search for more lakes before one day, man makes the trip to drill down into the planet itself.