NASA scientists today touted new evidence of a warm, wet and humid Mars that lasted for millions of years and could have supported life.
"Today's Mars is dry and probably has been that way for 2 billion years, but at one time Mars was shaped by water," said Ashwin Vasavada, NASA's deputy project scientist for the Mars rover Curiosity. "Rivers, lakes and ground water were present for millions of years. The atmosphere must have been thicker. Mars must have been warmer... and the climate system must have been loaded with water."
That means Mars at one time had the right ingredients and the right environment to support life, even if only in microbial form.
The finding is noteworthy not just for the scientific community but for NASA's Mars team as well. NASA sent Curiosity to the Red Planet to search for evidence that it could have once supported life.
The question now is how long life could have existed on Mars, according to Michael Meyer, lead scientist for NASA's Mars Exploration Program.
Meyer noted that Curiosity, which has been studying the surface of Mars since August 2012, has found evidence that there was once a large lake in Gale Crater, where the rover landed.
"Gale Crater had a large lake that could have lasted for millions of years," he said. "That's sufficient time for life to get started and thrive."
Curiosity, one of the two rovers still working on the planet, now is at the base of Mount Sharp, which was the ultimate goal for NASA's scientists once the robotic machine landed. It took a while for Curiosity to make its way to Mount Sharp, which rises up out of the middle of Gale Crater, because scientists sent it out to investigate other geographic formations first.
After taking on a dangerous six-mile journey in June 2013 to get to the base of Mount Sharp, Curiosity reached its destination and has been sending back images of the area. Those images are giving scientists clues as to why a three-mile-tall mountain arose out of the middle of a crater.
The mountain is made up of a series of sedimentary layers, NASA said today. Those layers appear to have been deposited by lakes, rivers and the wind.
"We are making headway in solving the mystery of Mount Sharp," said Curiosity Project Scientist John Grotzinger. "Where there's now a mountain, there may have once been a series of lakes."
He added in a new conference this afternoon that the rover collected samples from the lake bed -- and those lake deposits are not like the rocks that have been sampled on the plains.
At this point, Curiosity is studying the lowest sedimentary layers of Mount Sharp. Dubbed the Murray formation, this section of rock is 500 feet high. NASA scientists explained that 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 some river mouths on Earth.
These sedimentary deposits occurred repeatedly to form the mountain.
"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," said Grotzinger. "We may see how the chemistry changed in the lakes over time. This is a hypothesis supported by what we have observed so far, providing a framework for testing in the coming year."
This is not the first time the robotic rover has discovered proof that there once was water on Mars.
Not even two months after Curiosity began its work on the Red Planet, it found evidence of a "vigorous" thousand-year water flow there. Then, in September 2013, Curiosity found evidence that there also is frozen water in the soil on the Martian surface.
Scientists don't think that the water is just in the soil in the area tested but can be founded across the planet.