No. 154 - Imaging the target comet and approach-phase sky
The reporting period has seen the execution of the last payload hibernation preparatory activities with the activation of MIDAS, ALICE, and OSIRIS. The full payload complement is now ready for hibernation. The target comet and the sky that will be seen during the approach phase in summer 2014 have been imaged with OSIRIS and the navigation cameras in preparation for the science mission. During this activity, an anomalous acceleration of the spacecraft was observed, most likely due to outgassing of products accumulated during the rendezvous manoeuvre in January. In preparation for the hibernation entry manoeuvre, characterisations of the spacecraft inertia properties and of the Sun acquisition sensors were conducted.
During the reporting period, mission operations were conducted using the ESA New Norcia (NNO) ground station and the DSS-26 (Goldstone, 34 metres) and DSS-55 (Madrid, 34 metres) NASA Deep Space Network (DSN) antennas.
Main activities during reporting period
|MIDAS pre-hibernation activities|
|065||6-Mar-2011||DSS-55 2567||ALICE pre-hibernation activities|
|066||7-Mar-2011||NNO 2568||Spacecraft check-out 13|
|082||23-Mar-2011||NNO 2584||OSIRIS switch-on anomaly fix|
|085||26-Mar-2011||NNO 2587||Comet and approach-phase sky imaging|
|087||28-Mar-2011||NNO 2589||Spacecraft inertia and Sun acquisition sensor calibration for deep-space hibernation mode (DSHM) entry|
At the end of the reporting period on 28 March, Rosetta was 502 million kilometres from Earth (3.36 AU); one-way signal travel time was 1678 seconds (27 minutes 58 seconds). The distance from the Sun was 625.8 million kilometres (4.18 AU).
|ALICE||The instrument is currently OFF. The instrument was activated on DoY 065 (6 March) for the last mechanisms actuation before the hibernation phase.|
|CONSERT||The instrument is currently OFF.|
|COSIMA||The instrument is currently OFF.|
|GIADA||The instrument is currently OFF.|
|MIDAS||The instrument is currently OFF. The instrument was activated on DoY 064 (5 March) for the last mechanisms/piezos actuation before the hibernation phase. During this activation a small positioning error of the linear stage was observed, most likely due to low temperatures; this was corrected during activation on DoY 069 (10 March). The instrument is now ready for hibernation.|
|MIRO||The instrument is currently OFF.|
|OSIRIS||The instrument is currently OFF. The instrument was activated on DoY 082 (23 March) for the uplink of modified switch ON/OFF internal sequences to prevent accidental activation of the fail-safe actuators. The activity was followed by comet imaging, approach-phase sky imaging and hibernation preparation activities. The instrument is now ready for hibernation.|
|ROSINA||The instrument is currently OFF.|
|RPC||The instrument is currently OFF.|
|RSI||The USO is ON/muted since 3 February 2010 (DoY 032/2010).|
|VIRTIS||The instrument is currently OFF.|
|Lander (Philae)||The instrument is currently OFF.|
|SREM||The instrument is ON with standard settings since 3 February 2010 (DoY 032/2010).|
The spacecraft is now cruising towards the point where it can safely enter the hibernation phase. Data acquired during last tests will be processed and used to tune the hibernation entry operations. The solar arrays will be further tested before hibernation with a simplified procedure.
Summary of upcoming events:
- 31 March 2011: Solar arrays test at 4.2 AU
- 12 April 2011: Start of opposition phase
- 11 May 2011: Solar arrays test at 4.35 AU
- 20 May 2011: End of opposition phase
- 08 June 2011: Hibernation entry