Scientists have discovered signs of ancient water activity on Mars in a now- dried up lake system, adding to growing evidence that the Red Planet was once habitable for life, according to a new study.
The ancient lake at Jezero crater, located near the planet's equator, was first identified in 2005, and now Brown University researchers are saying that the onslaught of water that filled the crater was one of at least two separate periods of water activity in the region. It's hard to say just how long this lake system was active, but scientists speculate that it dried out approximately 3.5 to 3.8 billion years ago.
"We can say that this one really well-exposed location makes a strong case for at least two periods of water-related activity in Mars' history," Tim Goudge, who led the research, said in a news release. "That tells us something really interesting about how early Mars operated."
The lake's water supply supposedly came from two channels on the northern and western sides of the crater, which, at times, was brimming with so much water that any extra spilled into a third large channel. While it was still active, the lake system also deposited sediment in a delta-like deposit that, it turns out, contains traces of clay minerals - a clear sign of alteration by water.
However, 10 years after its initial discovery, Brown researchers wanted to learn exactly how those minerals formed - an issue that remains up for debate. Either the minerals formed in place in the lake, or they formed elsewhere and were transported into the lake.
To find out, Goudge and his colleagues collected high-resolution orbital images from NASA's CTX instrument, and combined them with data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard NASA's Mars Reconnaissance Orbiter. Using this data, they put together a detailed geological and mineralogical map of the entire Jezero crater paleolake system.
What they found was that each of the sediment deposits has its own distinct mineral signature that matches the signature of the watershed that it came from.
"That's a good indication that the minerals formed in the watershed and were then transported into the lake," Goudge said. (Scroll to read on...)
In addition, when the minerals formed and when they were transported into the lake deposit seem to have occurred at completely different times. According to the team's mapping data, the watershed showed a younger layer of rock that sits on top of the hydrated minerals, while the crater's inlet channels cut through that layer of younger rock. This means the water that carved the channels must have flowed well after the mineral layer had formed.
"What it implies is that there were actually two periods of water-related activity," Goudge explained. "The earlier episode formed the alteration minerals in the watershed, then some time later you had the surface water activity that transported the minerals into the lake. At this site, those two events appear not to have been genetically related."
This discovery could help reveal the history of water on Mars, which clearly was once much wetter than it is today. However, whether the Martian climate was warm enough to sustain liquid water at the surface, such as in the Jezero crater, for long periods of time remains to be seen.
NASA scientists have been using various instruments and technology such as the Opportunity and Curiosity rovers to find signs of water activity in the Red Planet's past and assess whether the Martian surface was ever once habitable for life.
Recent research even determined that a primitive ocean on Mars may have once held more water than is currently found in Earth's vast Arctic Ocean. Other evidence of water in Mars' past has come from ancient rock and volcanic activity that may have warmed Mars enough to harbor liquid water.
And now with two distinct events of water activity discovered in the Jezero crater, the likelihood that Mars was once teeming with life seems more plausible than ever. In fact, scientists may even land on the crater in the future with NASA's Mars 2020 rover. If life had emerged in either of the two water-related events, signs of it may well have been preserved at Jezero.
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