NASA MRO Mars Image
Orbiting the red planet NASA's Mars Reconnaissance Orbiter (MRO) has discovered evidence that warm, salty water may flow across Mars during its warmest months. NASA

New evidence suggesting the existence of water flowing on Mars indicates the possibility for life to exist on the Red Planet.

NASA's Mars Reconnaissance Orbiter have taken images and videos of dark, finger-like features running down a number of Martian slopes in the middle latitudes of the Planet's southern hemisphere. The lines become more visible in the warm season, suggesting that they could have been created by the flow of certain volatile chemicals which boils at low temperatures.

These flows then dry up in colder seasons. The strongest candidates are water and carbon dioxide, according to a study by planetary geologists at the University of Arizona.

Alfred McEwen, the lead author of the study, which was published in journal Science, says they could exclude carbon dioxide as temperatures were too high for it to exist in the form of frost. This means the flow marks were created in all probability by water.

"It is our first chance to see an environment on Mars that might allow for the expression of an active biological process, if there is present-day life on Mars," said Lisa Pratt, biogeochemist at Indiana University, Bloomington. Pratt was one of the participants on the NASA panel discussing the results on Thursday.

According to Pratt, Earth is the home for some organisms that live underground with almost no access to sunlight. Given the evidence of liquid salty water beneath Mars' surface, there is possibility of thriving life down there also, she said.

The water is said to be as salty as that in the Earth's ocean.

Saltiness lowers the temperature of water that would otherwise freeze. Locations where water flows actively become warm enough, even in the shallow spots, to sustain liquid water that is about as salty as Earth's oceans, while pure water would freeze at the observed temperatures.

"If there were to have been life on Mars and if it evolved and adapted to this permafrost world, I think those are reasonable things that we could go look for," NASA officials said in a press conference. "If there are cold salty waters that never freeze, despite the cold frozen surrounding ground, then they simply remain active at all times, although at lower metabolic rates when the coldest temperatures occur.

If the environment is one which it is liquid seasonally but pretty much freezes up solid at other times of the year, then that would have to be an organism that can go into a dormant state."

Taking the seasonality, latitude distribution and brightness into account, the supposed water would be a volatile material.

"It is more like a syrup, maybe, in how it flows," said McEwen.

If there is life on Mars, it can be traced now with better precision, as it is certain that the briny water on the red planet will hold clues to extant life. "... if there is extant life on Mars, it might be accessible in these brines, which gives us a new direction as to where to go," said McEwen.