The Curiosity ground team has been forced to switch the Mars rover to a redundant onboard computer, thanks to a memory problem.
The condition is related to a glitch in flash memory linked to the now-inactive computer that Curiosity was previously using. The swap puts the rover into 'safe mode' - a minimal-activity precautionary status. The team is now troubleshooting the problem.
"We switched computers to get to a standard state from which to begin restoring routine operations," says Richard Cook of NASA's Jet Propulsion Laboratory.
The two computers are dubbed A-side and B-side. Curiosity's now operating on its B-side, as it did during part of the flight from Earth to Mars. It operated on its A-side from before the August 2012 landing through last Wednesday.
"While we are resuming operations on the B-side, we are also working to determine the best way to restore the A-side as a viable backup," says JPL engineer Magdy Bareh, leader of the mission's anomaly resolution team.
The spacecraft remained in communication with the ground team at all scheduled communication windows on Wednesday - but didn't send recorded data, only current status information. This revealed that the computer hadn't switched to the usual daily 'sleep' mode when planned.
Diagnostic work in a testing simulation at JPL indicates the situation involved corrupted memory at an A-side memory location used for addressing memory files.
The glitch means that scientific investigations by the rover have had to be suspended, though they should start again in the next day or two.
Over the last week, laboratory instruments inside the rover have been analyzing portions of the first sample of rock powder ever collected from the interior of a rock on Mars.