THERE isn’t any scarcity of water on Mars. Astronomers reckon there’s at the very least 5m cubic kilometres of ice locked up beneath the planet’s dusty regolith. Whether or not any of it’s liquid is a trickier query.
Within the 1890s Percival Lowell, an American astronomer, popularised the thought that there have been canals criss-crossing the Martian floor, carrying water from the poles to feed a thirsty desert civilisation. Higher telescopes, and the arrival of house probes within the 1960s, revealed the canals as a mirage. Mars’s frigid temperatures, and the feeble stress exerted by its wispy environment, imply that no liquid water might survive on the floor for lengthy. However, in 2006 seasonal adjustments in a pair of Martian craters led astronomers to take a position that small quantities of liquid water is perhaps effervescent briefly to the floor within the Martian summer season. A decade later, although, the case remained unproven.
Now the query appears to have been settled in spectacular fashion. In a paper revealed in Science on July 25th, Roberto Orosei of the Nationwide Institute for Astrophysics in Italy, and his colleagues, report the invention of a lake of liquid water 20km throughout, buried 1.5km beneath Mars’s floor, near its southern polar ice cap. The lake appears to be a Martian cousin of acquainted Earthly options reminiscent of Lake Vostok, a subterranean lake in Antarctica.
The crew used low-frequency radar waves to look beneath the planet’s floor. Completely different supplies replicate the radar waves with completely different intensities, permitting scientists to see what’s there. The crew used a radar sensor on Mars Categorical, an orbiting probe, to survey a 200km-wide space of Planum Australe, the planet’s southern polar plain. The spacecraft’s radar sensor lacked the sensitivity of these used on Earth, however after greater than three years of accumulating information Dr Orosei felt assured sufficient to say that water was the one rationalization for the crew’s readings.
That the lake is underground is vital to its survival, says Susanne Schwenzer, a planetary scientist on the Open College, in Britain, who was not concerned with the work. As in Antarctica, the thickness of the ice sheet insulates the water from the sub-freezing temperatures on the planet’s floor. On the similar time, the stress exerted by the ice lowers the water’s melting level. And if the water is spiced with salts of sodium, magnesium and calcium—all of which have been discovered on Mars—its melting level might drop nonetheless additional.
The invention is thrilling from a purely geological perspective. However the greatest query is whether or not something is perhaps alive down there. There may be loads of life in Lake Vostok, despite the fact that it has been reduce off for tens of hundreds of thousands of years. Mars was a lot hotter and wetter up to now. Fossilised river deltas and lakebeds are seen on the planet’s floor. If microbial life did come up on Mars within the distant previous, it is perhaps clinging on in simply such an remoted pocket of water beneath the planet’s floor.
Maybe. Mars has been dry for round three.8bn years. That’s a very long time for a life-preserving lake to have endured. Dr Schwenzer factors out that Mars’s axis has wobbled sufficiently over the planet’s historical past that the polar caps have wandered broadly over its floor. However it’s an electrifying discovery nonetheless. The hopes of alien hunters have, lately, been shifting in the direction of the icy moons of Jupiter and Saturn, which sport giant oceans beneath their surfaces. Life on Mars is immediately again in rivalry.