NASA’s Curiosity Mars Rover Takes a Last Look at Mysterious Sulfur | JPL
NASA’s Curiosity rover is preparing for the next leg of its journey, a monthslong trek to a formation called the boxwork. It is a set of weblike patterns on Mars’ surface that stretches for miles. It will soon leave Gediz Vallis channel. How the channel formed so late during a transition to a drier climate remains a key question for the science team. Another interesting find is the field of white sulfur stones the rover discovered this past summer.
The rover is searching for evidence that ancient Mars had the right ingredients to support microbial life, if any formed billions of years ago, when the Red Planet held lakes and rivers. Located in the foothills of Mount Sharp, a 3-mile-tall (5-kilometer-tall) mountain, Gediz Vallis channel may help tell a related story—what the area was like as water was disappearing on Mars. Although older layers on the mountain had already formed in a dry climate, the channel suggests that water occasionally coursed through the area as the climate was changing.
Scientists are still piecing together the processes that formed features within the channel, including the debris mound nicknamed “Pinnacle Ridge." It appears that rivers, wet debris flows, and dry avalanches all left their mark. The science team is now constructing a timeline of events from Curiosity’s observations.
The science team is also trying to answer important questions about the sprawling field of sulfur stones. Images of the area from NASA’s Mars Reconnaissance Orbiter (MRO) showed what looked like an unremarkable patch of light-colored terrain. It turns out that the sulfur stones were too small for MRO’s High-Resolution Imaging Science Experiment (HiRISE) to see, and Curiosity’s team was intrigued to find them when the rover reached the patch. They were even more surprised after Curiosity rolled over one of the stones, crushing it to reveal yellow crystals inside.
Science instruments on the rover confirmed the stone was pure sulfur—something no mission has seen before on Mars. The team cannot yet explain why the sulfur formed there. On Earth, it is associated with volcanoes and hot springs, and no evidence exists of Mount Sharp having either of those causes present.
“We looked at the sulfur field from every angle—from the top and the side—and looked for anything mixed with the sulfur that might give us clues as to how it formed. We’ve gathered a ton of data, and now we have a fun puzzle to solve,” said Curiosity’s project scientist Ashwin Vasavada at NASA’s Jet Propulsion Laboratory in Southern California.
Spiderwebs on Mars
Curiosity has traveled about 20 miles (33 kilometers) since landing in 2012. It is now driving along the western edge of the Gediz Vallis channel, gathering a few more panoramas to document the region before traveling to the boxwork.
Viewed by MRO, the boxwork looks like spiderwebs stretching across the surface. It is believed to have formed when minerals carried by Mount Sharp’s last pulses of water settled into fractures in surface rock and then hardened. As portions of the rock eroded away, what remained were the minerals that had cemented themselves in the fractures, leaving the weblike boxwork.
On Earth, boxwork formations have been seen on cliffsides and in caves. However, Mount Sharp’s boxwork structures stand apart from those because they formed as water was disappearing from Mars and because they are so extensive, spanning an area of 6 to 12 miles (10 to 20 kilometers).
“These ridges will include minerals that crystallized underground, where it would have been warmer, with salty liquid water flowing through,” said Kirsten Siebach of Rice University in Houston, a Curiosity scientist studying the region. “Early Earth microbes could have survived in a similar environment. That makes this an exciting place to explore.”
More About Curiosity
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.
The University of Arizona, in Tucson, operates HiRISE, which was built by BAE Systems (formerly Ball Aerospace & Technologies Corp.), in Boulder, Colorado. JPL manages the Mars Reconnaissance Orbiter Project for NASA’s Science Mission Directorate in Washington.
science.nasa.gov/mission/msl-curiosity
science.nasa.gov/mission/mars-reconnaissance-orbiter
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