Nasa’s Mars Exploration Rover, the Spirit, is facing a glitch again, following four similar cases in 2009.

The rover is experiencing amnesia-like symptoms. It fails to record data from the day’s activities onto its non-volatile flash memory to retain the data while the rover powers down for energy-conserving periods of sleep.

The behaviour may delay the start of planned drives by Spirit to extricate itself from a patch of soft soil where its wheels have been embedded since April 2009.

Nasa’s Jet Propulsion Laboratory Mars exploration rover project manager, John Callas, said that they still don’t have information about what causes these amnesia events.

“If they are intermittent and infrequent, they are a nuisance that would set us back a day or two when they occur,” he said.

“If the condition becomes persistent or frequent, we will need to go to an alternate strategy that avoids depending on flash memory.”

The total volume of data returned by the rover through the alternate strategy is expected to be about the same.

Spirit has been working on Mars for over 69 months for mission originally planned for a three-month period.