Is there a Subglacial Lake on Mars’ South Pole?

The possibility of a massive subsurface lake near Mars’ south pole has been called into question by new computer simulations. These simulations suggest that tightly compacted layers of ice could produce radar reflections that are similar to those of liquid water.

In 2018, the European Space Agency’s Mars Express orbiter used its MARSIS instrument to identify what seemed to be a 20-kilometer-wide lake buried beneath 1.5 km of ice in Planum Australe, a region in the southern polar plain of Mars. Subsequent evidence suggested the existence of potentially dozens of such lakes, some of which are close to the surface, making it unlikely for liquid water to exist there.

However, conditions at the base of the south polar ice cap, along with the presence of calcium and magnesium perchlorate acting as natural antifreeze, could allow for the existence of briny lakes on Mars. This theory is supported by the measurements of the surface ice undulations in Planum Australe.

Despite the evidence, skepticism remains within the planetary science community. Cornell University scientists have proposed an alternative explanation for the radar echoes, suggesting that compacted ice layers could produce similar radar signals to those of a liquid lake. Their simulations showed that tightly packed ice layers crushed under the weight of the ice sheet could create bright radar reflections.

While the question of whether a briny lake exists beneath Mars’ south polar cap remains unanswered, the simulations offer a simpler explanation than the presence of a lake, according to lead researcher Daniel Lalich. The team’s findings were published in the journal Science Advances on June 7.

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