As well as commissioning the instruments, the ground controllers also tested each of the spacecraft's subsystems. There was a thrilling moment when one of the on-board computer memory units, known as the Solid State Mass Memory (SSMM), seemed to not respond properly during the instruments check-out. Good progress has been made on this issue in the last few days: a test involving all instruments was completed successfully by recording and recovering the data through the SSMM.
Unfortunately, during the commissioning of the power subsystem, ground engineers recorded an interconnection problem between the solar arrays and the power conditioning unit on board the spacecraft. This means approximately 70% of the power generated by the solar arrays is available for the satellite and its payload to use. This anomaly has no effect on the state of the spacecraft and has no impact on the mission during the whole trip to Mars, including the orbit insertion phase once at destination.
Despite this, the experts analysing the anomaly believe that even with this power shortage, the nominal Mars observation mission will be achievable. However, satellite payload operations may have to be reviewed for certain short periods of the mission.
Ground engineers are now preparing for the last of the payload's tests: the Beagle-2 lander will undergo its check-out on 4-5 July 2003. The experts are looking confidently to it. "In fact," says Rudolf Schmidt, Mars Express Project Manager, "overall, the spacecraft is in good shape. We are simply getting to know its personality."