Anomalies in the operation of the solid-state mass memory system on board Mars Express have caused science observations to be temporarily halted. A technical work-around is being investigated that will enable the resumption of a number of observations and should evolve into a long-term solution.
In mid-August, Mars Express autonomously entered safe mode, an operational mode designed to safeguard both the spacecraft itself and its instrument payload in the event of faults or errors.
The cause of entering the safe mode was a complex combination of events relating to reading from and writing to memory modules in the Solid-State Mass Memory (SSMM) system.
This is used to store data acquired by the instruments and housekeeping data from the spacecraft's subsystems, prior to its transmission to Earth, and is also used to store commands for the spacecraft that have been received from the ground stations, while awaiting execution.
Switch to spare memory controller
As the previous safe mode was three years ago and the current event looked like a 'normal' transition to safe mode, the flight control team executed the standard recovery procedure and restarted observations.
A few days later, another fairly similar set of SSMM problems occurred. The decision was then taken to switch over to the cold-redundant spare, or 'B-side', SSMM controller, as this was virtually the only subsystem common to the two events.
The decision to act was triggered by both the need to achieve stable science performance and the need to reduce the consumption of fuel caused by transitions to safe mode.
In mid-August, Mars Express autonomously entered safe mode, an operational mode designed to safeguard both the spacecraft itself and its instrument payload in the event of faults or errors.
The cause of entering the safe mode was a complex combination of events relating to reading from and writing to memory modules in the Solid-State Mass Memory (SSMM) system.
This is used to store data acquired by the instruments and housekeeping data from the spacecraft's subsystems, prior to its transmission to Earth, and is also used to store commands for the spacecraft that have been received from the ground stations, while awaiting execution.
Switch to spare memory controller
As the previous safe mode was three years ago and the current event looked like a 'normal' transition to safe mode, the flight control team executed the standard recovery procedure and restarted observations.
A few days later, another fairly similar set of SSMM problems occurred. The decision was then taken to switch over to the cold-redundant spare, or 'B-side', SSMM controller, as this was virtually the only subsystem common to the two events.
The decision to act was triggered by both the need to achieve stable science performance and the need to reduce the consumption of fuel caused by transitions to safe mode.
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