Discovery of a Big Surprise through a Rock on Mars

NASA’s Curiosity Cracked Open a Rock on Mars And Discovers a Big Surprise

An accident on Mars revealed the surprising contents of an otherwise unremarkable rock. A rock on Mars spilled a surprising yellow treasure after Curiosity accidentally cracked through its unremarkable exterior. These yellow crystals were revealed after NASA’s Curiosity happened to drive over a rock and crack it open. Using an instrument on the rover’s arm, scientists later determined these crystals are elemental sulphur, and it’s the first time this kind of sulphur has been found on the Red Planet. NASA’s Curiosity captured close-up image of a rock nicknamed “Snow Lake”. Among several recent findings, the rover has found rocks made of pure sulphur, a first on the Red Planet. When the rover rolled its 899-kilogram (1,982-pound) body over the rock, the rock broke open, revealing yellow crystals of elemental sulphur: brimstone. Although sulphates are fairly common on Mars, this represents the first time sulphur has been found on the red planet in its pure elemental form.

Scientists were stunned when a rock that NASA’s Curiosity Mars rover drove over cracked open to reveal something never seen before on the Red Planet: yellow sulphur crystals. Since the rover have been exploring a region of Mars rich with sulphates, a kind of salt that contains sulphur and forms as water evaporates. But where past detections have been of sulphur-based minerals, in other words, a mix of sulphur and other materials, the rock Curiosity recently cracked open is made of elemental, or pure, sulphur. It isn’t clear what relationship, if any, the elemental sulphur has to other sulphur-based minerals in the area. What's even more exciting is that the Gediz Vallis Channel, where Curiosity found the rock, is littered with rocks that look suspiciously similar to the sulphur rock before it got fortuitously crushed, suggesting that, somehow, elemental sulphur may be abundant there in some places. "Finding a field of stones made of pure sulphur is like finding an oasis in the desert," said Curiosity project scientist Ashwin Vasavada of NASA's Jet Propulsion Laboratory. "It shouldn't be there, so now we have to explain it. Discovering strange and unexpected things is what makes planetary exploration so exciting."

While people associate sulphur with the odour from rotten eggs (the result of hydrogen sulphide gas), elemental sulphur is odourless. It forms in only a narrow range of conditions that scientists haven’t associated with the history of this location. And Curiosity found a lot of it, an entire field of bright rocks which look similar to the one the rover crushed. The sulphur Curiosity found on Mars. Sulphates are salts that form when sulphur, usually in compound form, mixes with other minerals in water. When the water evaporates, the minerals mix and dry out, leaving the sulphates behind. These sulphate minerals can tell us a lot about Mars, such as its water history, and how it has weathered over time. Pure sulphur, on the other hand, only forms under a very narrow set of conditions, which are not known to have occurred in the region of Mars where Curiosity made its discovery. “Finding a field of stones made of pure sulfur is like finding an oasis in the desert,” said Curiosity’s project scientist, Ashwin Vasavada of NASA’s Jet Propulsion Laboratory in Southern California. “It shouldn’t be there, so now we have to explain it. Discovering strange and unexpected things is what makes planetary exploration so exciting.” There are, to be fair, a lot of things we don't know about the geological history of Mars, but the discovery of scads of pure sulphur just hanging about on the Martian surface suggests that there's something pretty big that we're not aware of. Sulphur, it's important to understand, is an essential element for all life. It's usually taken up in the form of sulphates, and used to make two of the essential amino acids living organisms need to make proteins.

It’s one of several discoveries Curiosity has made while off-roading within Gediz Vallis channel, a groove that winds down part of the 3-mile-tall (5-kilometer-tall) Mount Sharp, the base of which the rover has been ascending since 2014. Each layer of the mountain represents a different period of Martian history. Curiosity’s mission is to study where and when the planet’s ancient terrain could have provided the nutrients needed for microbial life, if any ever formed on Mars. Since we've known about sulphates on Mars for some time, the discovery doesn't tell us anything new in that area. We're yet to find any signs of life on Mars, anyway. But we do keep stumbling across the remains of bits and pieces that living organisms would find useful, including chemistry, water and past habitable conditions. Stuck here on Earth, we're fairly limited in how we can access Mars. Curiosity's instruments were able to analyse and identify the sulphurous rocks in the Gediz Vallis Channel, but if it hadn't taken a route that rolled over and cracked one open, it could have been sometime until we found the sulphur. NASA’s Curiosity Mars rover captured view of Gediz Vallis channel on March 31. This area was likely formed by large floods of water and debris which piled jumbles of rocks into mounds within the channel. Spotted from space years before Curiosity’s launch, Gediz Vallis channel is one of the primary reasons the science team wanted to visit this part of Mars. Scientists think that the channel was carved by flows of liquid water and debris that left a ridge of boulders and sediment extending 2 miles down the mountainside below the channel. The goal has been to develop a better understanding of how this landscape changed billions of years ago, and while recent clues have helped, there’s still much to learn from the dramatic landscape. The next step will be to figure out exactly how, based on what we know about Mars, that sulphur may have come to be there. That's going to take a bit more work, possibly involving some detailed modelling of Mars's geological evolution. Meanwhile, Curiosity will continue to collect data on the same.

Since Curiosity’s arrival at the channel earlier this year, scientists have studied whether ancient floodwaters or landslides built up the large mounds of debris that rise up from the channel’s floor here. The latest clues from Curiosity suggest both played a role: some piles were likely left by violent flows of water and debris, while others appear to be the result of more local landslides. The Gediz Vallis channel is an area rich in Martian history, an ancient waterway whose rocks now bear the imprint of the ancient river that once flowed over them, billions of years ago. While exploring Gediz Vallis channel, NASA’s Curiosity captured image of rocks which show a pale colour near their edges. These rings, also called halos, resemble markings seen on Earth when groundwater leaks into rocks along fractures, causing chemical reactions that change the colour. Those conclusions are based on rocks found in the debris mounds: Whereas stones carried by water flows become rounded like river rocks, some of the debris mounds are riddled with more angular rocks which may have been deposited by dry avalanches. Finally, water soaked into all the material that settled here. Chemical reactions caused by the water bleached white “halo” shapes into some of the rocks. Erosion from wind and sand has revealed these halo shapes over time. Curiosity drilled a hole in one of the rocks, taking a powdered sample of its interior for chemical analysis, and is still trundling its way deeper along the channel, to see what other surprises might be waiting just around the next rock. “This was not a quiet period on Mars,” said Becky Williams, a scientist with the Planetary Science Institute in Tucson, Arizona, and the deputy principal investigator of Curiosity’s Mast Camera, or Mastcam. “There was an exciting amount of activity here. We’re looking at multiple flows down the channel, including energetic floods and boulder-rich flows.”

While the sulphur rocks were too small and brittle to be sampled with the drill, a large rock nicknamed “Mammoth Lakes” was spotted nearby. Rover engineers had to search for a part of the rock that would allow safe drilling and find a parking spot on the loose, sloping surface. All this evidence of water continues to tell a more complex story than the team’s early expectations, and they’ve been eager to take a rock sample from the channel in order to learn more. After Curiosity bored its 41st hole using the powerful drill at the end of the rover’s 7-foot (2-meter) robotic arm, the six-wheeled scientist trickled the powderized rock into instruments inside its belly for further analysis so that scientists can determine what materials the rock is made of. Curiosity has since driven away from Mammoth Lakes and is now off to see what other surprises are waiting to be discovered within the channel. Curiosity was built by NASA’s Jet Propulsion Laboratory, which is managed by Caltech in Pasadena, California. JPL leads the mission on behalf of NASA’s Science Mission Directorate in Washington.