Images crystal shapes, mineral veins on Mount Sharp's Vera Rubin Ridge

Features hold clues to the fate of ancient water on Mars' surface.
By Laurel Kornfeld | Feb 10, 2018
NASA's Curiosity rover has captured images of intriguing geological features, including crystal shapes and mineral veins, at a region on the north slope of lower Mount Sharp in Mars' Gale Crater.

These features may reveal the history of water on ancient Mars as well as how the water was lost.

After climbing the ridge for five months, Curiosity reached its southern, uphill edge, which borders the rover's next destination, a region where orbiters detected high levels of clay minerals.

The rover is currently at a site on the ridge named Jura, a region characterized by pale, gray bedrock, in contrast to the rest of Vera Rubin Ridge, where the bedrock is red and contains hematite.

Visible within the fine-layered bedrock are tiny crystal-shaped bumps and mineral veins composed of both bright and dark materials.

Curiosity's science team is considering several theories regarding the origin of these features, including whether the original materials at the site crystallized or whether they dissolved and were replaced by different materials from which the crystals formed.

They are especially interested in any evidence of an ancient lake that subsequently dried or groundwater that flowed through sediment that had become embedded in rock.

There is also significant variation in the thickness of Jura's laminated bedrock and in the iron content of rocks in the area. The bedrock's characteristics suggest the area may be comprised of several geological layers.

Some of the crystals are elongated while others are V-shaped or star-like. They are approximately the size of a sesame seed.

Scientists think the laminated bedrock at Jura could either have formed when the lake in the area evaporated or later, when salty fluids moved through rock.

The crystals have some resemblance to gypsum crystals on Earth, with the brighter ones rich in calcium sulfate and the darker ones containing high levels of iron.

Curiosity Project Scientist Ashwin Vasavada of NASA's Jet Propulsion Laboratory(JPL) in California emphasized that each individual feature is a clue to the region's past.

"So far on this mission, most of the evidence we've seen about ancient lakes in Gale Crater has been for relatively fresh, non-salty water. If we start seeing lakes becoming saltier with time, that would help us understand how the environment changed in Gale Crater, and it's consistent with an overall pattern that water on Mars became more scarce over time," he said.

Differences in the mineral veins' iron content also holds clues to whether the region was once habitable for microbial life. Changes in fluid chemistry could have had a major impact on the region's habitability.

 

 

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