Since 2012, NASA Curiosity vagabond explored Gale Crater for clues to Mars’ past and possible evidence that it once supported life. For the past year, this research has focused on the lower levels of Mount Sharp, a transition zone between a region rich in clay and one filled with sulphates (a type of mineral salt). These regions may offer insight into Mars’ hot, watery past, but the transition zone between them is also of scientific value. In short, studying this region may provide a record of the major climate change that took place billions of years ago on Mars.
For example, this region has unique geological features that include clay minerals that appear as fluffy layers of sedimentary rock. One in particular, “The bow“, was recently photographed by Curiosity and thrilled the scientific teams of the mission. These features formed when water was still flowing through Gale Crater, depositing sediment at the base of Mount Sharp. Higher up the mountain, the hill was probably covered in windswept dunes that hardened into rock over time. Between them is where the foliated layers formed, perhaps as a result of small ponds or streams weaving them among the dunes.
As the rover climbs higher up Mount Sharp and through the transition zone, it detects fewer clay deposits and more sulfate-rich rocks. Soon the rover will drill its last sample from this area and analyze it to learn more about the changing mineral composition of these rocks. Analysis of this region should also provide insight into how groundwater ebbed and bloomed over time, leaving behind a complex geological record that indicates how the region experienced multiple “wet” periods before becoming the frozen, dedicated place it is today.
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Ashwin Vasavada, Curiosity project scientist at NASA’s Jet Propulsion Laboratory, Explain:
“We no longer see the lake deposits that we have seen for years lower on Mount Sharp. Instead, we see plenty of evidence of drier climates, like dry dunes that were sometimes surrounded by streams. This is a big change from the lakes that persisted for perhaps millions of years before.
In other rover related news, Curiosity has experienced health issues that indicate the rover is showing signs of aging. These include further damage to its treads, as well as an apparent instrument issue that caused the rover to go into safe mode. June 4ethe engineering team took new pictures of Curiosity wheels, which they did every 1,000 meters (3,281 ft) to check their general health. This has become particularly important since the rover team spotted the first breaks in its walks in 2017. Originally, the team performed wheel inspections every 500 meters (1,640 ft).
This was doubled after the introduction of a traction control algorithm to slow wheel degradation, which was seen as justification for fewer inspections. However, the latest photos of Curiosity wheels revealed that the left center wheel had damaged one of its characteristic zigzag treads (studs) – four of the nineteen studs on this wheel had already broken, making it the fifth. This prompted mission controllers to return to their original cadence and take images of the wheels every half kilometer (0.62 miles). Says Megan Lin, Curiosityproject manager at JPL:
“We have proven through ground testing that we can safely drive on the rims if necessary. If we ever reached the point where a single wheel had broken the majority of its lugs, we could take a controlled break to discard the remaining pieces. Due to recent trends, it seems unlikely that we will need to take such action. The wheels hold up well, providing the traction we need to continue our ascent.
The other problem arose on June 7 when CuriosityInternal temperature sensors indicated that one of its instrument control units had overheated. This caused the rover to automatically enter safe mode and shut down all but its most essential functions. Mission engineers at NASA’s Jet Propulsion Laboratory returned the rover to normal operation two days later, but are still trying to determine the exact cause of the problem. They suggested it could be from a bad temperature reading and have since switched to backup temperature sensors.
These signs of wear and possible malfunctions do not detract from Curiosity’s tenth anniversary, which will take place on August 5. With its mission extended indefinitely, it has no set timetable for its operations and will continue to explore until its radioisotope thermoelectric generator (RTG) dies or suffers a catastrophic failure. Waiting, Curiosity continues to ascend and scale Mount Sharp, gathering evidence of Mars’ past and looking for potential signs that it once supported life (and perhaps still could!)
Further reading: Nasa
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