Now controllers are evaluating the once-primary "A-side" computer to see if it can be repaired to act as a back up, while performing diagnostics with the "B-side" computer to get it up to full function.

The rover had been using its A-side computer system since before landing. The B-side system, now in operation, was last used during Curiosity's nine-month cruise from Earth to Mars.

"We need to go through a series of steps with the B-side, such as informing the computer about the state of the rover – the position of the arm, the position of the mast, that kind of information," Cook said.

The team has yet to determine what caused the memory problems, NASA said, but emphasised that the rover never lost contact with Earth. Cook had earlier said the problem may have been caused by a radiation hit.

The six-wheeled robot, with 10 scientific instruments on board, is the most sophisticated ever sent to another planet.