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No. 154 - Imaging the target comet and approach-phase sky

No. 154 - Imaging the target comet and approach-phase sky

Report for the period 5 to 28 March 2011This report covers 24 days of Rosetta mission operations. The main activities were the preparation of instruments for the hibernation phase, imaging the target comet and approach-phase sky with OSIRIS and the navigation cameras, and characterisation of the spacecraft's inertia properties and the Sun acquisition sensors.

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

DoY Date Pass Activity
064 5-Mar-2011

DSS-26 2566
NNO 2566

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
068 9-Mar-2011 NNO 2570 Monitor
069 10-Mar-2011 NNO 2571 Monitor
071 12-Mar-2011 NNO 2573 Monitor
073 14-Mar-2011 NNO 2575 Monitor
075 16-Mar-2011 NNO 2577 Monitor
076 17-Mar-2011 NNO 2578 Monitor
078 19-Mar-2011 NNO 2580 Monitor
080 21-Mar-2011 NNO 2582 Monitor
082 23-Mar-2011 NNO 2584 OSIRIS switch-on anomaly fix
083 24-Mar-2011 NNO 2585 Monitor
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

DoY = Day of year

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).

Payload Status
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).

Future Milestones

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

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Legal disclaimer
This report is based on the ESOC mission operations report, WOR #154. Please see the copyright section of the legal disclaimer (linked from the home page http://sci.esa.int) for terms of use.

Last Update: 1 September 2019
6-Jun-2020 15:15 UT

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