NASA's Curiosity Rover found clues of an ancient lake on Mars, shedding light on how water shaped this Martian landscape, new research explains.

Observations indicate that the Red Planet's Mount Sharp was built by sediments deposited in a large lake bed over tens of millions of years, suggesting that Mars once boasted a climate that could have held water. This discovery has important implications in the search of Martian life, past or present, on Mars.

"If our hypothesis for Mount Sharp holds up, it challenges the notion that warm and wet conditions were transient, local, or only underground on Mars," Ashwin Vasavada, Curiosity deputy project scientist at NASA's Jet Propulsion Laboratory (JPL), said in a statement.

"A more radical explanation is that Mars' ancient, thicker atmosphere raised temperatures above freezing globally," he added, "but so far we don't know how the atmosphere did that."

Signs of Life

NASA scientists have recently intensified their search for any sign of water on Mars, a hallmark sign of life, in the hopes of better understanding the ancient environment of our neighboring planet.

Prior research has shown evidence of rivers, streams and lakes on Mars, although it is not to suggest that this place was once a tropical paradise. Rather, it is more likely that this world experienced brief episodes of warmth and water. Once recent study even suggested that volcanoes may have warmed Mars enough to harbor water, by spewing greenhouse gases like sulfur dioxide into the typically cool atmosphere.

Also, the deep impact Gale Crater, which Curiosity has extensively surveyed, revealed Earth-like soil dating back some 3.7 million years, suggesting that microbial life may have survived.

Mountain or Lake?

And now the mysterious Mount Sharp, located along the Gale Crater, adds to the growing evidence of a possibly habitable Martian environment. The mountain stands about 3 miles (5 kilometers) tall and is composed of hundreds of rock layers with lake, river and wind deposits. So even though this layered mountain now sits in a crater, it may have once actually been the site of a vast lake, much larger and longer-lasting than any previously examined close-up.

"We are making headway in solving the mystery of Mount Sharp," added Curiosity Project Scientist John Grotzinger.

Curiosity is currently studying the lowest sedimentary layers of Mount Sharp, a section of rock 500 feet (150 meters) high, dubbed the Murray formation. Based on what the rover has found so far - after taking a stroll around the Mars mountain twice - scientists believe that ancient rivers carried sand and silt to the lake, depositing the sediments at the mouth of the river to form deltas similar to those found at river mouths on Earth. This cycle supposedly repeated itself year after year.

Over time, the Curiosity team suggests, these sediment deposits hardened into layers that ultimately formed the Mount Sharp seen today.

"The great thing about a lake that occurs repeatedly, over and over, is that each time it comes back it is another experiment to tell you how the environment works," Grotzinger said. "As Curiosity climbs higher on Mount Sharp, we will have a series of experiments to show patterns in how the atmosphere and the water and the sediments interact. We may see how the chemistry changed in the lakes over time."

Mission to Mars

This latest evidence goes along with previous research that supports the idea that ancient Mars once boasted wet environments; however, researchers have yet to figure out what ancient conditions could have led to a habitable Martian planet.

But Curiosity's assessment can help guide the way, as well as prepare astronauts in search of Martian life during future missions. NASA plans to launch a manned mission to Mars in the 2030s, an undertaking NASA's chief says is necessary for human survival.

More information about Curiosity can be found on the rover's website here.

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