ESA Science & Technology - No. 38 - Rosetta back in Cruise Mode

The spacecraft was gradually re-configured to cruise mode in various steps: on 11 March the X-band link was re-established via the HGA; three On-Board Control Procedures (OBCPs) were updated on 15 March and the antenna to be selected for Survival Mode was changed back to MGA on 24 March.

In addition the periodic Attitude and Orbit Control System (AOCS) checkout was carried out on 17 March; on this occasion the AOCS was configured back to 3 reaction wheels and 1 IMP gyro, as planned for cruise. On 24 and 25 March slews were performed to characterise the disturbance torques in the upcoming Near Sun Hibernation Mode (NSHM) attitude.

All spacecraft activities were carried out successfully and the spacecraft performance remains excellent.

On the payload side, in the reporting period two outstanding commissioning activities were carried out.

• The boresight calibration of VIRTIS-H (VIRTIS - High resolution optical subsystem) on 16 March, for the third time did not succeed in determining the instrument boresight. The PI Team is investigating the problem.
• The ROSINA activities covered upload of the new on-board software to the redundant Data Processing Unit (DPU) and more troubleshooting of the Reflectron Time of Flight Spectrometer (RTOF). The activities were successfully completed but more calibration and parameter setting work will be required in the future in order to stabilise the ROSINA RTOF instrument functions.

A total of 9 New Norcia passes of a fixed duration of 7 hours commanding were taken (four passes per week). A total of 7 DSN tracking passes were taken until 18 March. This completed the DSN support for Rosetta Earth swing-by 1.

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 083) Rosetta was at 6.73 million km from the Earth. The one-way signal travel time was 22.4 seconds.