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The possibility of life on Mars is a topic of great interest. When looking for life beyond Earth, scientists often follow the water.
In 2018, scientists reported a subglacial lake on Mars, under the ice at the south pole of Mars. It is presumed to be a body of salt water about 20 km (12 miles) wide.
Now, additional observations confirmed the presence of that lake and found three more. The lakes extend for about 75,000 square kilometers. The largest central lake is 30 kilometers wide and is surrounded by three smaller lakes, each a few kilometers wide.
The scientists used a radar instrument on Mars Express called the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) to probe the planet’s south polar region. MARSIS sends out radio waves that bounce off layers of material on the planet’s surface and underground.
The way the signal is reflected indicates the type of material present in a particular location: rock, ice, or water. A similar method is used to identify underground glacial lakes on Earth. The team detected some areas of high reflectivity that indicate bodies of liquid water trapped under more than a kilometer of Martian ice.
Although the surface of Mars was periodically wet and could have been hospitable to microbial life billions of years ago, if such deposits exist, they could be potential habitats for Martian life.
But the amount of salt present could pose problems. The underground lakes of Mars are believed to have a reasonably high salt content for the water to remain liquid. Although so low the surface, there may be a small amount of heat from the interior of Mars, this alone would not be enough to melt the ice into water.
John Priscu, an environmental scientist at Montana State University, said: “Lakes with a salt content five times that of seawater can support life, but as you get 20 times closer, seawater is no longer present. There is not much active life in these salty pools of Antarctica. They are just pickled. And that could be the case [on Mars]. “
Elena Pettinelli from Italy’s Roma Tre University said: “We don’t just have an occasional body of water here, but a system. The system probably existed a long time ago, when the planet was very different, and this is perhaps the remnant of that. “
The discovery, reported Sept. 28 in Nature Astronomy.
