More memory issues for Mars Rover Opportunity

Chuck Bednar for redOrbit.com – @BednarChuck

Despite a recent attempt to fix the memory issues that plagued it late last year, the Mars Rover Opportunity has once again started experiencing amnesia-like events, officials from the NASA Jet Propulsion Laboratory (JPL) in Pasadena, California have revealed.

As Discovery News reported on Tuesday, a corrupt flash data bank caused Opportunity to begin “forgetting” valuable data near the end of 2014, causing random resets to take place throughout the day and hindering the mission’s progress. In an attempt to fix the issue, engineers attempted to adopt a “no-flash mode” to avoid use of the corrupted area by temporarily storing data to the rover’s volatile memory and regularly transmitting it back to Earth.

The engineers uploaded a software patch to avoid use of the damaged flash memory bank, and on March 20, they reformatted the rover’s memory. However, it appears that while the worst of the memory issues are over, the problem has not completely been solved just yet.

“We changed how the rover uses flash memory in an attempt to correct problems the rover had been experiencing,” said John Callas, project manager for Opportunity at JPL. “Although we are a little disappointed at the occurrence of an amnesia event only five days after reformatting, we are not surprised. There is still no clear understanding of what is causing the problems.”

“Only time will tell if we have been successful in mitigating the most serious flash problems,” he added. The latest event did not result in the loss of any scientific data, JPL said, and Opportunity was able to continue its regularly scheduled activities – using tools on its robotic arm to examine a rock target identified by NASA scientists as “Athens,” the US space agency noted.

Flash memory causing problems

Flash memory allows the rover to retain stored data when the power is turned off, which happens every night as Opportunity looks to conserve energy created by its solar panels. For three months prior to last week, the rover operated using only its volatile memory, which stores data while the vehicle remains operational, and downloaded it each day before it was shut down for the night.

NASA explains that Opportunity has seven banks of flash memory, and they traced the previous issues had been traced back to Bank 7. The recent fix instructed the rover to avoid the use of that particular bank, and the reformatting allowed the rover to resume use of the other six. No overall cause of the rover’s flash memory problems has yet been determined, and the agency is confident that the most serious issues have been successfully resolved – for now, that is.

Still kicking after 11 years

Opportunity first arrived on Mars along with its twin rover, Spirit, in 2004. Its mission was only scheduled to last three months, but 11 years later Opportunity is still going, recently becoming the first vehicle ever to travel the distance of a marathon race on another world. It is currently examining the outcrops on the western rim of Endeavour Crater, where clay minerals have been detected by NASA’s Mars Reconnaissance Orbiter.

Don’t peter out on us yet, Opportunity!

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Source: http://www.redorbit.com/news/space/1113363713/more-memory-issues-for-mars-rover-opportunity-040115/