Mars may have been a watery and temperate place in the distant past, but it’s been a giant dustball for many eons. That doesn’t mean there aren’t interesting things on the planet and even the potential for life. Liquid water may be largely absent on the surface, but a stunning new analysis from the European Space Agency (ESA) says there’s plenty of it in a vast underground lake near the planet’s south pole.
This analysis comes from data collected by the venerable Mars Express orbiter, which has studied the red planet for nearly 15 years. This spacecraft carries an instrument called the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument (MARSIS). It was the first-ever radar sounder brought to another planet, but the team was unable to determine if it detected water on Mars until now.
Scientists working on the project have developed new techniques to generate higher-resolution images of what lurks beneath the surface of Mars. After processing and reprocessing data from 2012 to 2015, the researchers believe they’ve detected a large subsurface lake. The unnamed body of water is near the south pole of the planet. This isn’t as strange as you might think; after all, Antarctica has hundreds of subsurface lakes like Lake Vostok.
Radar images of reflective regions that suggest the presence of liquid water.
The radar data from Mars Express shows water packed between layers of ice and dust spanning about 20 kilometers (12.4 miles) at a depth of 1.5 kilometers (0.9 miles). If this body of water is anything like Earth’s Antarctic lakes, it is kept liquid by two processes. First, the water is probably very high in salt content. Salt based on magnesium, calcium, or sodium can interfere with the bonding of water molecules to form a brine. This lowers the freezing temperature dramatically. Brine lakes on Earth can remain liquid at temperatures as low as 8.6 degrees Fahrenheit (-13 degrees Celsius). In addition, pressure from the layers of ice and dust above the lake can also lower the freezing point.
The truly remarkable thing here is the Mars Express data only covered a swath of the planet about 200 kilometers (124 miles) across. There could be similar deposits in other places around the planet just waiting to be found. It’s not even outlandish to think there could be living organisms in these bodies of water. On Earth, we have found living microorganisms in Antarctic lakes. Future Mars missions will include more powerful radar systems that could reveal these hidden worlds in greater detail.
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