Fresh analysis of spectrometric data from the Mars Reconnaissance Orbiter shows that a crater named for NASA astronomer Dean McLaughlin may have at one time been the basin for a ground-water fed lake. Scientists base this on the deposits of what are known as “carbonate rocks,” detected by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) array housed on the Orbiter.
Carbonate rocks are sedimentary rocks that form when carbon precipitates out of water. Over centuries, small amounts of minerals form larger and larger coatings, eventually becoming the rocks that the MRO scientists were looking to find. But, because there don’t seem to be any obvious tributaries – rivers or streams – present as there are elsewhere on Mars, the assumption is that this lake was formed by water seeping up from beneath the crater to fill the basin:
The new information comes from researchers analyzing spectrometer data from NASA’s Mars Reconnaissance Orbiter, which looked down on the floor of McLaughlin Crater. The Martian crater is 57 miles (92 kilometers) in diameter and 1.4 miles (2.2 kilometers) deep. McLaughlin’s depth apparently once allowed underground water, which otherwise would have stayed hidden, to flow into the crater’s interior.
McLaughlin Crater is approximately 100 miles from the landing site of the short-lived Pathfinder expedition, which launched in 1996. It is about 160 or so lines of longitude away from the Curiosity rover, so it stands to reason that this is not a feature of Mars that Curiosity will be exploring. You can see in the image the concentric circular shapes that scientists believe are the layers of sedimentary rock.