Nasa's doddering Martian rover Opportunity is losing its marbles

Nasa's Mars rover Opportunity has been working well into its golden years - after nearly 11 years roaming the Red Planet, it has survived more than 40 times past its warranty. But now, this trusty veteran is experiencing some worrisome memory loss.

The long-lived rover has been having some senior moments, according to John Callas, project manager for the Mars Exploration Rover mission - as Opportunity and its defunct twin Spirit are formally known. The episodes of amnesia stem from faulty flash memory - the kind of memory in your digital camera that allows your pictures to stay saved even after your device is turned off.

But flash memory does not last forever - and the seventh, final bank in the flash memory appears to be malfunctioning.

"Flash memory has a limited lifetime," Callas said. "It only allows so many read-write cycles before it starts to wear out some of the cells. And after 11 years of operation on Mars, we now suspect we're seeing a wear-out of some of those cells."

This leads to a pair of problems. Since the rover can't use the seventh memory bank, it uses its random-access memory - or RAM, the kind of memory your computer uses when it is on for temporary data storage. The problem is, as soon as the rover - or your computer - is switched off, the information stored in RAM is lost. So if the rover turns off before sending all of its at-risk data back to its handlers at the Jet Propulsion Laboratory in La Canada Flintridge, then that data is lost forever.

That was an annoying, but manageable, issue, Callas said. The second snag is that the flash memory issue also causes the rover to reboot - and when it reboots, it stops the long-term activities the team had planned for the rover and simply waits for further instructions on the ground.