Curiosity Astrobiology Rover Discovers Pure Sulfur Crystals On Mars
Among several recent findings, the Mars Curiosity rover has found rocks made of pure sulfur — a first on the Red Planet.
Scientists were stunned on May 30 when a rock that NASA’s Curiosity Mars rover drove over cracked open 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 with sulfates, a kind of salt that contains sulfur and forms as water evaporates. But where past detections have been of sulfur-based minerals — in other words, a mix of sulfur and other materials — the rock Curiosity recently cracked open is made of elemental, or pure, sulfur. It isn’t clear what relationship, if any, the elemental sulfur has to other sulfur-based minerals in the area.
While people associate sulfur with the odor from rotten eggs (the result of hydrogen sulfide gas), elemental sulfur is odorless. 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 that look similar to the one the rover crushed.
These yellow crystals were revealed after NASA’s Curiosity happened to drive over a rock and crack it open on May 30. Using an instrument on the rover’s arm, scientists later determined these crystals are elemental sulfur Credit: NASA/JPL-Caltech/MSSS Full Image Details
Close-Up of Sulfur Crystals — These sulfur crystals were found inside a rock after NASA’s Curiosity Mars rover happened to drive over it and crush it on May 30, 2024, the 4,200th Martian day, or sol, of the mission. This image was captured by Curiosity’s Mars Hand Lens Imager (MAHLI), a camera on the end of its robotic arm, on June 4, 2024, the 4,205th Martian day, or sol, of the mission.This rock was nicknamed “Convict Lake” after a location in California’s Sierra Nevada. Curiosity’s Alpha Particle X-Ray Spectrometer (APXS) found that the crystalline material is elemental sulfur. Larger image
“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.”
Pan around this 360-degree video to explore Gediz Vallis channel, the location where NASA’s Curiosity Mars rover discovered sulfur crystals and drilled its 41st rock sample. The images that make up this mosaic were captured by the rover’s MastCam in June. Credit: NASA/JPL-Caltech/MSSS
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.
NASA/JPL-Caltech/MSSS NASA’s Curiosity Mars rover captured this view of Gediz Vallis channel on March 31. This area was likely formed by large floods of water and debris that piled jumbles of rocks into mounds within the channel. Credit: NASA/JPL-Caltech/MSSS Full Image Details
Floods and Avalanches
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.
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.
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 that 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.
NASA’s Curiosity Mars rover captured this close-up image of a rock nicknamed “Snow Lake” on June 8, 2024, the 4,209th Martian day, or sol, of the mission. The image was captured by Curiosity’s Mars Hand Lens Imager (MAHLI), a camera on the end of the rover’s robotic arm. Nine days before this image was captured, Curiosity crushed a similar-looking rock and revealed crystalline textures inside. Curiosity’s Alpha Particle X-Ray Spectrometer (APXS) found that the rock was made of elemental sulfur. An entire field of similar-looking rocks were found in this area; all are expected to have sulfur inside them. Larger image
Astrobiology
