No. 73 - First Preparations for Mars Swing-by
During the reporting period the following activities have been conducted:
- OSIRIS observations of asteroid Lutetia: the scientific data are being processed by the OSIRIS team
- Thermal characterisation for the Mars Swing-by attitude, with a solar aspect angle (SAA) of 165° at 1.25 AU. This activity has proven the feasibility of the MSB scenario from a spacecraft point of view. A final go-ahead shall be given by the Lander team after having analysed the internal temperatures
- Switch-over activities for the Attitude and Orbit Control Measurement System Interface Unit (AIU)
- On-board software maintenance (OBSM) activities for intermediate Sun distance conditions and MSB preparation. With this activity the spacecraft is configured to operate in the current environment with respect to the Sun, and the Electrically Erasable Programmable Read Only Memory (EEPROM) AOCS software is such that it can operate in the eclipse conditions as required for the MSB
All activities have been conducted according to the plan without any problems. A double SEU (single event upset) has been detected by the SSMM in one of the memory modules, recovery activities are being conducted according to the procedure and without any impact on operations.
A total of 8 New Norcia (NNO) passes (4x8h commanding, 4x4h tracking) were taken during this period and 2 DDOR measurements were performed. DSN support consisted in 9x4h tracking passes and 2 DDOR measurements.
| NNO Pass |
Date | DOY | Main Activity |
| 1040 | 03.01.07 | 003 | Lutetia observation |
| 1041 | 04.01.07 | 004 | Lutetia observation |
| 1046 | 09.01.07 | 009 | Thermal characterisation for MSB and AIU reconfiguration |
| 1047 | 10.01.07 | 010 | OBSM activities for intermediate Sun distances and MSB preparation |
At the end of the reporting period (DOY 012) Rosetta was at 313.5 million km from Earth (2.09 AU) and the one-way signal travel time was 17 minutes 26 seconds. The distance to the Sun was 189.4 million km (1.26 AU).
Spacecraft
Thermal
The thermal behaviour of the spacecraft is nominal and stable. On DOY 010 the system has been configured for intermediate Sun distances (ITM), including the required Thermal Control Table (TCT) updates.
Payload
The reporting period included off-line activities for OSIRIS (observations of asteroid Lutetia on DOY 002 to 004) and the lander Philae (thermal characterisation for MSB on DOY 007). SREM was operating in the background during the reporting period.
Both activities have been conducted according to the plan and data have been made available to the PI teams for further analysis.
Future Milestones
The MSB Phase formally started on 28 July 2006. The actual Mars swing-by will take place on 25 February 2007, followed by a Deep Space Manoeuvre in April 2007.
Preparation activities for the MSB have started on DOY 010 with the configuration of the spacecraft on-board software maintenance (OBSM) for this phase. They will continue in the coming weeks with the following plan:
- DOY 024: Update of lander Philae EEPROM
- DOY 031: IMP configuration
- DOY 039: Trajectory correction manoeuvre
The navigation campaign will enter now its most dense phase with several tracking passes per week and DDOR measurements, both with ESA and DSN stations.
The ground segment will now start the formal validation campaign for the Mars Swing-by scenario. This will include a set of scenarios simulations, review meetings, and navigation reports.
