Liquid water lake discovered on Mars
The European Space Agency (ESA) has uncovered evidence for an underground pond at the planet’s south pole
Radar data collected by ESA’s Mars Express suggests that, packed between layers of ice and dust, is a body of liquid water spanning some 20 kilometres (12.4 miles) at a depth of 1.5 kilometres (0.9 miles) at Mars’ south pole.
Liquid water has been suspected at the base of the polar ice caps for some time, especially given our studies of Earth. After all, it’s wellknown that the melting point of water decreases under the pressure of an overlying glacier. Moreover, the presence of salts on Mars could further reduce the melting point of water and keep a fluid even at belowfreezing temperatures.
It was Mars Express’ Mars Advanced Radar for Subsurface and Ionosphere Sounding Instrument, or MARSIS, that made the discovery. However, scientists working on the mission had to develop a series of new techniques to tease a story out of what was originally inconclusive data. “We had to come up with a new operating mode to bypass some onboard processing and trigger a higher sampling rate, thus improving the resolution of the footprint of our dataset; now we see things that simply were not possible before,” explains Andrea Cicchetti, MARSIS operations manager. “We'd seen hints of interesting subsurface features for years, but we couldn't reproduce the result from orbit to orbit because the sampling rates and resolution of our data was previously too low.”
The finding is somewhat reminiscent of Lake Vostok, discovered some four kilometres
(2.5 miles) below the ice in Antarctica on Earth. Some forms of microbial life are known to thrive in Earth's subglacial environments, but could underground pockets of salty, sediment-rich liquid water on
Mars also provide a suitable habitat, either now or in the past? Whether life has ever existed on Mars remains an open question, and it’s one that Mars missions, including the current European-Russian ExoMars, will continue to explore.
“The long duration of Mars Express, and the exhausting effort made by the radar team to overcome many analytical challenges enabled this much-awaited result, demonstrating that the mission and its payload still have a great science potential,” says Dmitri Titov, Mars Express project scientist. "This thrilling discovery is a highlight for planetary science and will contribute to our understanding of the evolution of Mars, the history of water on our neighbour planet and its habitability."