Coming on the heels of much speculation over tiny, fleeting bits of water on the surface of the Red Planet, a Mars orbiter has recently spotted a massive lake of it beneath the planet’s southern ice sheets. “This is potentially a really big deal,” said planetary scientist Briony Horgan of Purdue University in West Lafayette, Indiana. “It’s another type of habitat in which life could be living on Mars today.”
The lake – estimated to be around 20 kilometres across – has been discovered by Roberto Orosei of the National Institute of Astrophysics in Bologna, Italy and a team of collaborators by building upon more than three years of observations from the European Space Agency’s orbiting Mars Express spacecraft.
Combining 29 radar observations taken between May 2012 and December 2015, the MARSIS (which stands for Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument aboard the spacecraft revealed a bright spot in the ice layers near the planet’s south pole.
The MARSIS instrument works by sending radar waves towards the surface and recording the brightness of the resulting image, which indicates the composition of the target material (liquid water makes a brighter echo than either ice or rock).
Having considered other potential explanations for the image obtained from the spacecraft (none of which are very convincing), the researchers conclude that Mars likely has liquid water even today. Furthermore, similar lakes beneath the ice in Antarctica have been found using the same method.
Even though the lake is probably infused with large amounts of salt which keeps it liquid at a temperature of -67° Celsius, it could still be suitable for extra-terrestrial life forms. “If this [lake] is confirmed, it’s a substantial change in our understanding of the present-day habitability of Mars,” commented NASA’s Planetary Protection Officer Lisa Pratt.
Before the celebrations begin, however, more work has to be done to reconcile the data received from the spacecraft and other similar radar experiments, which have failed to detect water on Mars, even when using high-definition 3D images of the same poles.
“I expect there will be debate,” said planetary scientist Isaac Smith of the Planetary Science Institute. “They’ve done their homework. This paper is well earned. But we should do some more follow-up.”