Although Curiosity exited safe mode and returned to normal operations two days later, JPL’s engineers are still analyzing the exact cause of the issue. They suspect safe mode was triggered after a temperature sensor provided an inaccurate measurement, and there’s no sign it will significantly affect rover operations since backup temperature sensors can ensure the electronics within the rover body aren’t getting too hot.
The rover’s aluminum wheels are also showing signs of wear. On June 4, the engineering team commanded Curiosity to take new pictures of its wheels – something it had been doing every 3,281 feet (1,000 meters) to check their overall health.
The team discovered that the left middle wheel had damaged one of its grousers, the zig-zagging treads along Curiosity’s wheels. This particular wheel already had four broken grousers, so now five of its 19 grousers are broken.
The previously damaged grousers attracted attention online recently because some of the metal “skin” between them appears to have fallen out of the wheel in the past few months, leaving a gap.
The team has decided to increase its wheel imaging to every 1,640 feet (500 meters) – a return to the original cadence. A traction control algorithm had slowed wheel wear enough to justify increasing the distance between imaging.
“We have proven through ground testing that we can safely drive on the wheel rims if necessary,” said Megan Lin, Curiosity’s project manager at JPL. “If we ever reached the point that a single wheel had broken a majority of its grousers, we could do a controlled break to shed the pieces that are left. Due to recent trends, it seems unlikely that we would need to take such action. The wheels are holding up well, providing the traction we need to continue our climb.”
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