For the past year, NASA’s Curiosity Mars rover has traveled through a transition region from a clay-rich region to one filled with a salty mineral called sulfate. While the scientific team focused on the clay-rich region and the sulfate-laden region as evidence each can offer about Mars’ watery past, the transition zone also proves to be scientifically fascinating. In fact, this transition could set the record for a major shift in Mars’ climate billions of years ago that scientists are just beginning to understand.
The clay minerals were formed when lakes and streams once lapped Gale Crater, depositing sediment at what is now the base of Mount Sharp, the 3-mile-high (5-kilometer) mountain whose foothills Curiosity has been rising since 2014. on the mountain in the transition zone, Curiosity’s observations show that the streams dried up into droplets and sand dunes that formed over the lake’s sediments.
“We no longer see the lake deposits that we saw for years lower on Mount Sharp,” said Ashwin Vasavada, Curiosity project scientist at NASA’s Jet Propulsion Laboratory in Southern California. “Instead, we see a lot of evidence of drier climates, such as dry dunes with occasional streams flowing around them. That’s a big change from the lakes that might have held out millions of years ago.”
As the rover climbs higher through the transition zone, it detects less clay and more sulfate. Curiosity will soon drill the last rock sample it will take in this zone, providing a more detailed understanding of the changing mineral composition of these rocks.
Unique geological features also stand out in this zone. The hills in the area probably started in an arid environment of large, wind-blown sand dunes, which hardened into rock over time. Among the remnants of these dunes lie other water-carried sediments, perhaps deposited in ponds or small streams that once wove between the dunes. These sediments now appear as erosion-resistant piles of scaly layers, such as one nicknamed ‘The Prow’.
Adding to the story’s richness and complexity is the knowledge that there were multiple periods when groundwater ebb and flow over time, leaving behind a jumble of puzzle pieces that Curiosity’s scientists had to piece together in a precise timeline.
Ten years later, hard at work
Curiosity celebrates its 10th year on Mars. 5 Though the rover is showing its age after a full decade of exploration, nothing has stopped it from continuing its ascent.
On June 7, Curiosity went into safe mode after detecting a temperature reading on an instrument control box in the rover’s body that was warmer than expected. Safe mode occurs when a spacecraft detects a problem and automatically shuts down all but the most essential functions, allowing engineers to assess the situation.
Although Curiosity exited safe mode and returned to normal operation two days later, JPL engineers are still analyzing the exact cause of the problem. They suspect that safe mode was activated after a temperature sensor gave an inaccurate reading, and there’s no sign that this will significantly affect the rover’s operation, as backup temperature sensors can keep the electronics in the rover body from working too hard. gets hot.
The aluminum wheels of the rover also show signs of wear. On June 4, the engineering team ordered Curiosity to take new photos of its wheels — something it had done every 1,000 meters to check their overall health.
The team found that the left center wheel had damaged one of the grooves, the zigzagging treads along Curiosity’s wheels. This particular wheel already had four broken cams, so now five of the 19 cams are broken.
The previously damaged mopeds recently attracted attention online because some of the metal “skin” between them appears to have fallen out of the wheel in recent months, leaving a hole.
The team has decided to increase the image of the wheel to every 500 meters, a return to the original cadence. A traction control algorithm had slowed the wheel wear down enough to justify increasing the spacing between the imaging.
“We’ve proven through ground testing that we can safely drive on the rims if needed,” said Megan Lin, Curiosity Project Manager at JPL. “If we ever got to the point where a single wheel had broken a majority of its sponges, we could take a controlled break to shed the pieces that are left. Due to recent trends, it seems unlikely that we should need to take such action The wheels hold up well and provide the traction we need to continue our climb.”
Curiosity Mars Rover diverts away from ‘gator-back’ rocks
Provided by Jet Propulsion Laboratory
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