ESA Science & Technology - No. 39 - First Payload Passive Checkout

An ALICE Moon observation was executed from the Mission Timeline on 26 March, thus completing payload operations as part of the Earth swing-by phase.

The first Payload Passive Checkout was executed from the Mission Timeline between 26 and 30 March. In addition, a pass was taken on 6 April to perform checkout measurements for the Radio Science experiment. One monitoring pass was taken on 29 March, whereas most of the housekeeping and science checkout data were dumped on 31 March and 1 April, as per the standard Passive Checkout timeline.

The telemetry retrieved on 29 March indicated that MIDAS had been switched-off autonomously during the first part of its checkout on 27 March due to an unexpected high value of the instrument LCL current. The investigation of the problem lead to the detection of an anomaly in the conversion of Operational Requests into commands. MIDAS was the only user affected by this anomaly. An extra New Norcia pass was taken on 30 March to disable the execution of the second part of the MIDAS Checkout. Since then, the instrument has not been reactivated. Upon request of the MIDAS Team, a slot to functionally checkout all instrument subsystems was scheduled for 19 April.

For all other instruments, the checkout sequences executed successfully.

On the platform side, two Solid State Mass Memory (SSMM) blocks, which had been declared "failed on-board" last year due to double Single Event Upsets, were successfully recovered on 5 April. This allowed to complete the SSMM file reconfiguration initiated in December 2004.

A total of 7 New Norcia passes (NNO passes) of a fixed duration of 7 hours commanding were taken, at three passes per week. In addition, a short unplanned pass of 2 hours was taken on 30 March to support recovery activities following MIDAS autonomous switch-off during the Passive Checkout. The table below shows a chronology of the main activities in the reporting period.

At the end of the last New Norcia pass in the reporting period (DOY 097) Rosetta was at 11.08 million km from the Earth. The one-way signal travel time was 37 seconds.