Impressive rock formations documented by the Curiosity rover provide evidence of a dry climate in the Red Planet’s ancient past.
The clay minerals formed when lakes and streams once rippled across Gale Crater, depositing sediment at what is now the base of Mount Sharp, the 3-mile-tall (5-kilometer-tall) mountain whose foothills Curiosity has been ascending since 2014. Higher on the mountain in the transition zone, Curiosity’s observations show that the streams dried into trickles and sand dunes formed above the lake sediments.
“We no longer see the lake deposits that we saw for years lower on Mount Sharp,” said Ashwin Vasavada, Curiosity’s project scientist at NASA’s Jet Propulsion Laboratory in Southern California. “Instead, we see lots of evidence of drier climates, like dry dunes that occasionally had streams running around them. That’s a big change from the lakes that persisted for perhaps millions of years before.”
As the rover climbs higher through the transition zone, it is detecting less clay and more sulfate. Curiosity will soon drill the last rock sample it will take in this zone, providing a more detailed glimpse into the changing mineral composition of these rocks.
NASA’s spacecraft on Mars are all affected by the Red Planet’s winds, which can produce a little dust devil or a global dust storm. Credit: NASA/
Ten years later, going strong
Curiosity will celebrate its 10th year on Mars on August 5th. As the rover shows its age after a full decade of exploration, nothing has stopped it from continuing its ascent.
On June 7, Curiosity entered safe mode after detecting a temperature reading on an instrument control box inside the rover’s body that was hotter than expected. Safe mode occurs when a spacecraft detects a problem and automatically shuts down all but the most essential functions so engineers can assess the situation.
Although Curiosity came out of safe mode and returned to normal operations two days later, JPL engineers are still analyzing the exact cause of the problem. They suspect that safe mode was triggered after a temperature sensor provided an inaccurate measurement, and there is no sign that this will significantly affect the rover’s operations, as the backup temperature sensors can ensure that the electronics inside the rover rover’s body do not get too hot.
The rover’s aluminum wheels are also showing signs of wear. On June 4, the engineering team ordered Curiosity to take new pictures of its wheels – something it had been doing every 3,281 feet (1,000 meters) to check its overall health.
The team found that the middle left wheel had damaged one of its claws, the zigzag steps along Curiosity’s wheels. This particular wheel already had four claws broken, so now five of its 19 claws are broken.
The previously damaged claws have attracted attention online recently because some of the metal “skin” between them appears to have fallen off the wheel in recent months, leaving a gap.
The team decided to increase their wheel image to every 1,640 feet (500 meters) – a return to the original cadence. A traction control algorithm reduced the wear on the wheels enough to justify increasing the distance between images.
“We’ve proven through ground tests that we can safely drive on the wheel rims if necessary,” said Megan Lin, Curiosity’s project manager at JPL. “If we ever got to the point where a single wheel had broken most of its grips, we could do a controlled break to loosen the pieces that were left over. Given recent trends, it seems unlikely that we need to take such action. The wheels are holding up well, providing the traction we need to continue our climb.”