Giant Mars Crater Shows Evidence of Ancient Lake
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 This view of layered rocks on the floor of McLaughlin Crater shows sedimentary rocks that contain spectroscopic evidence for minerals formed through interaction with water. The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter recorded the image. Image released Jan. 20, 2013.CREDIT: NASA/JPL-Caltech/Univ. of Arizona |
New photos of a huge crater on Mars suggest water may lurk in crevices under the planet's surface, hinting that life might have once lived there, and raising the possibility that it may live there still, researchers say.
Future research looking into the chances of life on Mars could shed light on the origins of life on Earth, scientists added.
The discovery came from a study of images by NASA's powerful Mars Reconnaissance Orbiter that revealed new evidence of a wet underground environment on the Red Planet. The images focused on the giant McLaughlin Crater, which is about 57 miles (92 kilometers) wide and so deep that underground water appears to have flowed into the crater at some point in the distant past.
Today, the crater is bone-dry but harbors clay minerals and other evidence that liquid water filled the area in the ancient past.
"Taken together, the observations in McLaughlin Crater provide the best evidence for carbonate forming within a lake environment instead of being washed into a crater from outside," study lead author Joseph Michalski, of the Planetary Science Institute in Tucson, Ariz., and London's Natural History Museum, said in a statement. [Search for Water on Mars (Photos)]
An annotated look at the huge McLaughlin Crater on Mars, showing locations of minerals and clays created by water in the ancient past. The region may have once been a groundwater lake billions of years ago. Image released Jan. 20, 2013.CREDIT: NASA/JPL-Caltech/Univ. of Arizona
A wet Mars underground
Space agencies have deployed many missions to Mars over the decades to explore how habitable its surface may have been or is today. However, the Martian surface has been extremely cold, arid and chemically hostile to life as we know it for most of the history of Mars.
Instead of scanning the surface of Mars for life, scientists have suggested the most viable habitat for ancient simple life may have been in Martian water hidden underground.
On Earth, microbes up to 3 miles (5 km) or more underground make up perhaps half of all of the planet's living matter. Most of these organisms represent some of the most primitive kinds of microbes known, hinting that life may actually have started underground, or at least survived there during a series of devastating cosmic impacts known as the Late Heavy Bombardment that Earth and the rest of the inner solar system endured about 4.1 billion to 3.8 billion years ago.
Since Mars has less gravity — a surface gravity of a little more than one-third Earth's — its crust is less dense and more porous than that of our planet, which means that more water can leak underground, researchers said. Wherever there is liquid water on Earth, there is virtually always life, and microbes underground on Mars could be sustained by energy sources and chemical reactions similar to those that support deep-dwelling organisms on Earth.
"The deep crust has always been the most habitable place on Mars, and would be a wise place to search for evidence for organic processes in the future," Michalski told SPACE.com. [Search for Life on Mars: A Timeline (Gallery)]
Subterranean Mars
While researchers currently have no way to drill deep underground on the Red Planet, they can nevertheless spot hints of what subterranean Mars is like by analyzing deep rocks exhumed by erosion, asteroid impacts or materials generated by underground fluids that have welled up to the surface.
Such upwelling would first occur in deep basins like McLaughlin Crater — as the lowest points on the surface, they would be where underground water reserves would most likely get exposed.
Scientists focused on McLaughlin Crater because it is one of the deepest craters on Mars. McLaughlin is about 1.3 miles (2.2 km) deep and is located in Mars' northern hemisphere.
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