Mars may possess liquid water beneath its ruddy surface, according to a new finding from a NASA rover on the Red Planet. This is the first evidence that the ingredient, critical for life as we know it, could exist in liquid form near the equator.

The Curiosity rover discovered evidence that salty water may be hidden in equatorial regions, just beneath the surface of the planet. Perchlorate salts could be preventing water from freezing in the cold desert conditions.

Mars orbiters previously uncovered evidence of recurring slope lineae, temporary liquid water. The finding was made through the study of temperature and humidity data from the roving laboratory on the Red Planet.

Curiosity was launched to Mars on Nov. 26, 2011, arriving at the Red Planet on Aug. 6, 2012. The roving laboratory is exploring Gale crater, located just south of the equator of Mars.

Brine water appears to be forming in the top 2 inches beneath the Martian surface each night, as water vapor from the atmosphere collects in the tawny material. This liquid then evaporates each morning, leaving behind arid dirt.

"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," Morten Bo Madsen, leader of the Mars Group at the Niels Bohr Institute at the University of Copenhagen, said.

Astronomers believe that when Mars first formed, the planet had a thicker atmosphere than we see today, allowing the presence of large quantities of water on its surface. Sediment layers in Gale crater suggest that the feature may once have been a large lake. Nearly all of the water on Mars later evaporated into space, leaving behind the desert world we see today.

Small rounded pebbles in Gale Crater appear to be formed by the action of running water. New observations reveal layers of sedimentary deposits, leaning toward Mount Sharp.

"Very fine-grained sediments, which slowly fell down through the water, were deposited right at the very bottom of the crater lake. The sediment plates on the bottom are level, so everything indicates that the entire Gale crater may have been a large lake," Bo Madsen said.

Alien life is unlikely to be found on Mars, however, as the amount of water deposited by this process is  too sparse to maintain the processes of life.

"It is not just a problem of water, but also temperature. The water activity and temperatures are so low in Mars that they are beyond the limits of cell reproduction and metabolism," said Javier Martin-Torres, of the Lulea University of Technology. Solar radiation also is a factor as without a global magnetic field to protect the atmosphere, the radiation is so powerful that it penetrates at least one meter into the surface, killing life as we recognize it.

The presence of highly corrosive perchlorates, or salts, makes conditions even more challenging for life.

This information on the presence of brine adds to recent findings that there is eough water trapped as ice at the planet's poles and extending toward the equator to cover Mars to a depth of 3 feet. Dust overlays the ice, keeping it from evaporating. Atmospheric pressure on Mars is so low that any exposed ice instantly disappears, turning into water vapor, but the dust preserves the stores of ice.

Study of the new data from the Curiosity rover was published in the journal Nature Geoscience.