Mars has liquid water just below its surface, according to new measurements by Nasa’s Curiosity rover.
Until now, scientists had thought that conditions on the red planet were too cold and arid for liquid water to exist, although there were known to be deposits of ice.
The latest findings suggest that Martian soil is damp with liquid brine, due to the presence of a salt that significantly lowers the freezing point of water. When mixed with calcium perchlorate liquid water can exist down to around -70C, and the salt also soaks up water vapour from the atmosphere.
New measurements from the Gale crater show that during winter nights until just after sunrise, temperatures and humidity levels are just right for liquid brine to form.
Morten Bo Madsen, a senior Mars scientist at the University of Copenhagen and a co-investigator on the Curiosity rover, said: “The soil is porous, so what we are seeing is that the water seeps down through the soil. Over time, other salts may also dissolve in the soil and now that they are liquid, they can move and precipitate elsewhere under the surface.”
Liquid water is traditionally considered an essential ingredient for life as we known it, but Mars remains hostile for other reasons, the scientists said.
The latest findings are unlikely to change the view that if life ever blossomed on Mars, it probably died out more than a billion years ago.
“There are organisms on Earth, halophiles, that can survive in salty environments, but if it’s also very cold and very dry that’s a problem” said Mr Madsen. “The radiation on Mars nails it – that environment is very hostile.”
– (Guardian service)