The Curiosity rover has found something amazing: rocks made of pure sulfur.
NASA open The discovery was reported in a post last week, which describes how the rover was driving along the Geddes Vallis channel — a formation thought to have been carved by a river about three billion years ago. The channel is interesting because the ridges provide a good look at many layers of Martian rock.
The canal is a known source of sulphates: a salty substance formed when water evaporates. The presence of sulphates is another reason we visited the Gediz Valles canal.
While Curiosity was working, the mobile laboratory crushed a rock, and upon further inspection, it was found to be composed entirely of pure sulfur.
Yellow sulfur crystals were revealed after NASA’s Curiosity rover flew over and broke off a rock on May 30. Image credit: NASA/JPL-Caltech/MSSS – Click to enlarge
The spacecraft also spotted several other rocks that, from the outside, looked like a piece of pure sulfur it crushed.
Sulfur only forms under specific conditions, so finding large amounts of it in one place is exciting and unexpected.
“Finding a field of rocks made of pure sulfur is like finding an oasis in the desert,” said Ashwin Vasavada, Curiosity’s project scientist at NASA’s Jet Propulsion Laboratory in Southern California. “It shouldn’t be there, so now we have to explain it. Finding strange and unexpected things is what makes planetary exploration so exciting.”
The NASA article did not put forward any theory explaining the presence of sulfur.
But it does offer some insight into what Curiosity saw in the Geddes Vallis channel: evidence of a few different processes at work on the landscape.
“Since Curiosity arrived in the channel earlier this year, scientists have been studying whether ancient floodwaters or landslides may have created large piles of debris rising from the channel floor here,” the post reads, before presenting analysis that suggests both may have played a role. “Some of the piles were likely left behind by violent flows of water and debris, while others appear to have been the result of localized landslides.”
The condition of the debris observed by Curiosity supports this hypothesis — some of the objects seen in the hills near the channel were “rounded like river rocks” while other sections were “full of more angular rocks that may have been deposited by dry avalanches.”
To help think about this, and the sulfur situation, Curiosity unscrewed its drill and drilled a new hole in the Red Planet. The target for this hole—the 41st one ever drilled by a rover on Mars—was a rock called Mammoth Lakes, chosen because it is close to the sulfur rocks, but larger and less fragile. The drill’s sample is now stored inside Curiosity for review by the rover’s Sample Analysis at Mars (SAM) instrument suite.
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