ESA Science & Technology - No. 44 - Preparations for observing Deep Impact comet encounter

On the spacecraft side, various maintenance activities were carried out, including on 16 June a test of the Star Tracker (STR) performance (CCD health check) to investigate an anomaly detected during commissioning and the upload of outstanding patches to the EEPROMs (Electrically Erasable Programmable Read Only Memory) of the Data Manager Subsystem (DMS) and the Attitude and Orbit Control System (AOCS) on 21 June.

In addition thermal reconfiguration activities took place: the APME/Thrusters Hot setting was removed on 21 June and the Thermal Monitoring Table (TMT) updated on 23 June with settings derived from post-launch experience. Finally, in preparation for the Deep Impact payload operations, information distribution to the payload was enabled on 21 June and the attitude control was configured to four reaction wheels on 22 June.

Various payload activities were executed in the reporting period. On 14 and 15 June a complete OSIRIS on-board software upload was executed and tested. This software successfully solved two anomalies detected during commissioning and allowed OSIRIS to be declared GO for Deep Impact operations.

On 16 June RPC was activated to allow a software patch activity for the LAP instrument, also to close an earlier detected anomaly. During this pass the RPC team observed that a sensor of the MAG instrument was not properly activated and requested a second power-on test. This test was executed on 22 June and showed a nominal MAG behaviour.

On 21 June the Lander was activated to update its Stored TeleCommands Buffer (STCB) table. At switch on the Lander Control Centre noticed that the Lander had automatically switched to Data Processing Unit 2 (DPU2). The patch activities were successful on this DPU. On 23 June a special test was executed to check the DPU1 status and confirmed the same behaviour (autonomous switchover to DPU2). The Lander team is investigating and will propose further troubleshooting activities.

SREM (Standard Radiation Environment Monitor) is continuously active in the background for radiation monitoring.

A total of 6 New Norcia passes of a max duration of about 9 hours commanding were taken over the reporting period (three passes per week).

At the end of the reporting period (DOY 175) Rosetta was at 60.9 million kilometres from the Earth. The one-way signal travel time was 3 minutes and 23 seconds.