After more than a decade of traversing the red planet, NASA's Mars Opportunity rover is facing some problems in its old age — namely, ones with memory. According to Discovery News, the rover has been going through bouts of "amnesia" thanks to failures in its flash memory storage.
"The Opportunity rover uses two different types of memory: "volatile" and "non-volatile," NASA project manager John Callas told Discovery News. The volatile memory is akin to a computer's RAM, so any data stored there is wiped every time the rover shuts down. The non-volatile memory is where the important data like telemetry — the measurements the rover is collecting — is stored so that it can be accessed whenever Opportunity is powered on. The problem with the non-volatile memory, as with most physical storage, is that there are limits to how many times you can read from and write to it before it starts to degrade.
With enough time, Opportunity's memory will eventually fail
That degradation has begun to occur more frequently, and at times has left the rover unable to access the non-volatile memory. When this happens, Opportunity defaults to trying to write the telemetry data to the volatile memory, which inevitably gets wiped when the rover goes to sleep — something that occurs often to keep the batteries charged. It's as if Opportunity is forgetting these important bits, which is why NASA is referring to it as amnesia.
The memory issue can be mitigated as long as the rover has a chance to relay telemetry data to the orbiting Mars Odyssey spacecraft, but there are times when that isn't possible in between shutdowns. There's also a bigger problem at hand — repeated, unsuccessful attempts to save to the non-volatile flash memory are causing Opportunity to completely reboot. That means command sequences, which are sometimes sent in bunches, can also be forgotten, drastically slowing the team's progress.
There is good news, however. NASA engineers believe that the corruption is occurring primarily in one of the Rover's seven memory banks, and if that's the case then they believe it could only be a matter of weeks before they can program Opportunity to only use the six that aren't corrupted.
Mars Opportunity fulfilled its original mission just three months after landing in 2004, so all the data and knowledge gained in the decade since has been a bonus for team scientists. Since then, it has traveled over 26 miles across the surface of Mars — the furthest of any planetary rover.