Curiosity rover finds evidence of liquid water on Mars

April 14, 2015 08:58
Samples analyzed by the Curiosity rover indicate that conditions were right for the brines to form during winter nights at the Martian equator. Photo: NASA

NASA's Curiosity rover has found that water can exist as a liquid just below the Martian surface.

Although Mars is too cold to support liquid water at the surface, salts in the soil lower its freezing point and allow briny films to form, BBC News reported.

Scientists say thin films of water form when salts in the soil, called perchlorates, absorb water vapor from the atmosphere. 

The results, published in the journal Nature Geoscience, support the theory that dark streaks seen on the planet's crater walls could be formed by flowing water.

However, the temperature of these liquid films is about -70C, too cold to support microbial life forms. 

Also, the brines would be exposed to high levels of cosmic radiation, another threat to life.

But it's still possible that organisms could exist somewhere beneath the surface, where conditions are more favorable, the report said.

Samples analyzed by the rover indicate that conditions were right for the brines to form during winter nights at the Martian equator, where Curiosity landed. But the liquid evaporates at daytime as temperatures rise.

Javier Martin-Torres, a co-investigator on the Curiosity mission, said the evidence was indirect but convincing.

"What we see are the conditions for the formation of brines on the surface. It's similar to when people were discovering the first exoplanets," Martin-Torres told the BBC.

"They were not seeing the planets, but they were able to see the gravitational effects on the star.

"These perchlorate salts have a property called deliquescence. They take the water vapor from the atmosphere and absorb it to produce the brines."

That scientists see evidence for these brines at the Martian equator -- where conditions are least favorable -- means that they might be more persistent at higher latitudes, in areas where the humidity is higher and temperatures are lower, the report said.

-- Contact us at [email protected]