Dear @s colleagues and friends @s,
A dear colleague shares this interesting article, published on July 18, 2024 by NASA and translated by us for this space. Let's see what it's all about...
Scientists were stunned on May 30 when a rock passed over by NASA's Curiosity Mars rover shattered to reveal something never seen before on the Red Planet: yellow sulfur crystals.
Since October 2023, the rover has been exploring a region of Mars rich in sulfates, a type of salt that contains sulfur and forms as water evaporates. But while previous detections have been of sulfur-based minerals (in other words, a mixture of sulfur and other materials), the rock that Curiosity cracked recently is made of elemental (pure) sulfur. It's not clear what relationship, if any, elemental sulfur has with other sulfur-based minerals in the area.
While people associate sulfur with the smell of rotten eggs (a result of hydrogen sulfide gas), elemental sulfur is odorless. It forms only under a narrow range of conditions that scientists have not associated with the history of this place. And Curiosity found a lot of that: an entire field of glowing rocks that look like the one crushed by the rover.
“Finding a field of stones made of pure sulfur is like finding an oasis in the desert”,
said the Curiosity project scientist, Ashwin Vasavada from 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.”
It's one of several discoveries that Curiosity made while traveling inside the Gediz Vallis channel, a furrow that descends through part of Mount Sharp, 5 kilometers high, whose base the rover has been climbing 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 it ever formed on Mars.
Floods and avalanches
Discovered from space years before the launch of Curiosity, the Gediz Vallis channel is one of the main reasons why the scientific team wanted to visit this part of Mars. Scientists believe that the channel was excavated by flows of liquid water and debris that left a ridge of rocks and sediment that extends 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 is still much to learn from this spectacular landscape.
Since the arrival of Curiosity to the channel earlier this year, scientists have been studying whether ancient floods or landslides formed the large mounds of debris that rise here from the channel floor. The latest clues from Curiosity suggest that both played a role: some clumps of material were probably left behind by violent flows of water and debris, while others appear to be the result of more local landslides.
Those conclusions are based on rocks found in debris mounds: while stones carried by water flows become rounded like river rocks, some of the debris mounds are riddled with more angular rocks that may have been deposited by dry avalanches.
Finally, the water soaked up all the material that settled here. The chemical reactions caused by the water bleached forms of white “halos” in some of the rocks. Erosion caused by wind and sand has revealed these forms of haloes over time.
“This was not a quiet period on Mars,”
said Becky Williams, a scientist at the Planetary Science Institute in Tucson, Arizona, and adjunct principal investigator of Curiosity's Mast Camera, or Mastcam.
“There was an exciting amount of activity here. We are seeing multiple flows along the channel, including severe flooding and rock-rich flows.”
A hole in 41
All of this water evidence continues to tell a more complex story than the team's initial expectations, and they were eager to take a rock sample from the channel to learn more. On June 18, they had their chance.
While the sulfur rocks were too small and fragile to be sampled with the drill, a large rock nicknamed “Mammoth Lakes” was seen nearby. The rover's engineers had to search for a part of the rock that would allow safe drilling and find a place to park on the loose, sloping surface.
After Curiosity drilled its 41st hole using the powerful drill at the end of the rover's 2-meter (7-foot) robotic arm, the six-wheeled scientist inserted powdered rock into instruments inside his belly for further analysis so that scientists can determine what materials the rock is made of.
Since then, curiosity has moved away from Mammoth Lakes and now heads to see what other surprises are waiting to be discovered within the channel.
