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No. 111 - Deep space manoeuvre 4 and thermal characterisation

No. 111 - Deep space manoeuvre 4 and thermal characterisation

Report for Period 14 February to 20 March 2009The reporting period covers five weeks of active cruise phase characterised by several activities both on the spacecraft and the payload side.

Major activities performed during the reporting period are:

  • thermal characterisation for Lutetia fly-by (in July 2010)
  • pre-payload check-out 10 (pre-PC10) activities for ALICE and RPC
  • update of on-board control procedure protocol (OBCP) for memory dump management
  • recovery activities for OSIRIS, COSIMA and VIRTIS
  • Deep Space Manoeuvre 4

The Deep Space Manoeuvre 4 has been successfully performed on 18 March 2009, in preparation of Rosetta's third and last Earth swing-by planned for 13 November 2009.

During the reporting period mission operations have been conducted with support of the ESA New Norcia (NNO) ground station.

DOY Date Pass Main Activity
047 16/02/09 NNO 1817 Thermal characterisation
(Sun elevation: 175°)
048 17/02/09 NNO 1818 Thermal characterisation
(Sun elevation: 175-192°)
049 18/02/09 NNO 1819 Thermal characterisation
(Sun elevation: 192°)
050 19/02/09 NNO 1820 Monitoring
051 20/02/09 NNO 1821 Monitoring
054 23/02/09 NNO 1824 Monitoring
056 25/02/09 NNO 1826 COSIMA recovery action
061 02/03/09 NNO 1831 ALICE software 2.06 uploaded to all Electrically Erasable Read Only Memory (EEPROM) pages
064 05/03/09 NNO 1834 VIRTIS software 4.1 upload
068 09/03/09 NNO 1838 OSIRIS shutter recovery action - 1
069 10/03/09 NNO 1839 OSIRIS shutter recovery action - 2
071 12/03/09 NNO 1841 ALICE software 2.06 functional test.
RPC pre-PC10 activities.
Uplink of new OBCP for platform memory dump management
075 16/03/09 NNO 1845 Monitoring
076 17/03/09 NNO 1846 Monitoring
077 18/03/09 NNO 1847 Deep space manoeuvre 4
078 19/03/09 NNO 1848 Monitoring
079 20/03/09 NNO 1849 Monitoring

At the end of the reporting period (DoY 079) Rosetta was at 408.66 million km from Earth (2.73 AU) and the one-way signal travel time was 1363 seconds. The distance to the Sun was 322.48 million km (2.15 AU).

Thermal Characterisation

The thermal behaviour of the spacecraft remains nominal and stable. A thermal characterisation has been conducted between DoY 047 (14:00 UT) and DoY 049 (14:00 UT) to verify both the spacecraft's and instruments' thermal performance for Rosetta's fly-by of asteroid Lutetia in July 2010.

During the three-day thermal characterisation the spacecraft was exposed to the Sun with an elongation angle of first +175°, and later +192° from the +Z axis (positive direction towards +X axis). Each attitude has been maintained for 24 hours, judged as the time required for thermal stabilisation. This test was conducted at a Sun distance of 2.21 AU, whereas the Lutetia fly-by will be at 2.7 AU from the Sun. The spacecraft successfully passed the test and did not have any problem in sustaining the attitudes, verifying its thermal performance for the 2010 Lutetia fly-by operations.

On the payload side, both the ROSINA and the VIRTIS instruments reported non-ideal conditions when going to 192° (meaning exposure of the back side of the spacecraft to the Sun). The ROSINA instrument observed an outgassing that could disturb its asteroid measurements. During the actual Lutetia fly-by operations an early exposure of the back side of the spacecraft is therefore favoured for the instrument. VIRTIS has recorded too high temperatures of the sensors that would affect the science results. To prevent this would impose a very short exposure of the backside of the spacecraft. These factors will all have to be taken into account when defining the final science operations requirements for the Lutetia fly-by.

Spacecraft

Payload
Several recovery activities, software updates and test activities have been performed with the scientific instruments during the reporting period. The Standard Radiation Environment Monitor (SREM) continues to run in the background:

ALICE
The instrument was activated on DoY 061 to patch software v2.06 in all Electrically Erasable Read Only Memory (EEPROM) pages. A short functional test was successfully performed on DoY 071.

CONSERT
The instrument is OFF.

COSIMA
The instrument was activated between DoY 054 and 056 to perform recovery activities. The Target Manipulation Unit (TMU) is now fully recovered. The problem encountered with COSIMA during the asteroid Steins fly-by campaign in September 2008 is now fully understood and operational changes will prevent it from occurring again.

GIADA
The instrument is OFF.

MIDAS
The instrument is OFF.

MIRO
The instrument is OFF.

OSIRIS
The instrument temperatures were observed during the thermal characterisation and were found to be nominal at all times.
The instrument was activated on DoY 068 and 069 to test new control approaches for the shutter. The test was successful and the behaviour of the instrument has been very good. The investigation will now continue in view of having a fully operational instrument (both WAC and NAC) for the Earth swing-by 3 operations in November this year.

ROSINA
The instrument was activated as part of the thermal characterisation activities.

RPC
The instrument was activated on DoY 071 to carry-out preparatory activities in view of the payload checkout 10.

RSI
The instrument is muted.

VIRTIS
The instrument participated in the thermal characterisation activities.
The instrument was again activated on DoY 064 to uplink software v4.1 in both EEPROMs.

LANDER Philae
The instrument participated in the thermal characterisation activities. It passed the three-day attitude tests successfully without any problems.

SREM
Since DoY 026/2009 the accumulation settings are configured for active cruise mode.


Future Milestones

The active cruising phase will continue until end of March when the spacecraft will be configured for a Near Sun Hibernation (NSH) Phase to last until beginning of September. The entry into NSH, originally foreseen for the end of April, was brought forward three weeks to minimise the interference with the potential launch of the Herschel and Planck missions in terms of ground station usage.


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Legal disclaimer
This report is based on the ESOC mission operations report, WOR #111. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.

Last Update: 1 September 2019
18-Sep-2021 07:41 UT

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