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No. 131 - Asteroid Lutetia flyby test

No. 131 - Asteroid Lutetia flyby test

Report for Period 27 February to 26 March 2010The reporting period covers four weeks of Rosetta mission operations. These were dedicated to further payload maintenance activities and a rehearsal of the flyby of asteroid Lutetia. The rehearsal of the asteroid flyby dynamics went very smoothly and gives good confidence in the spacecraft behaviour for the actual flyby in July 2010.

The last tests of the RTOF, one of the three sensors of Rosetta's neutral and ion mass spectrometer, ROSINA, were successfully performed on 1 and 4 March. The RTOF sensor has now been declared operational.

On 16 March OSIRIS performed observations of the comet-like object P/2010-A2. Because of its appearance (long dust tail and small nucleus) and its position in the main asteroid belt the object is considered to be among the group of rare main-belt comets, which are thought to be icy asteroids that experience episodes of cometary activity. The true nature of P/2010-A2, however, is still unclear and it could also be the remnant of a very rare event: the collision of two asteroids.

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

DOY Date Pass Main Activity
060 01/03/10 NNO 2196

ROSINA RTOF test

063 04/03/10 NNO 2199

ROSINA RTOF test

068 09/03/10

NNO 2204

Monitoring pass

071 12/03/10

NNO 2207

Monitoring pass

074 15/03/10

NNO 2210

Lutetia flyby test (started on DOY 073)

075 16/03/10

NNO 2211

OSIRIS observation of P/2010-A2

081 22/03/10 NNO 2217

Monitoring pass

DOY = Day of year

At the end of the reporting period (DOY 085) Rosetta was at 149.7 million km from Earth (1.00 AU) and the one-way signal travel time was 499 seconds. The distance to the Sun was 277.7 million km (1.84 AU).

Lutetia flyby test

On 14 and 15 March (DOY 073/074) a test was performed in preparation of Rosetta's flyby of asteroid Lutetia, which will take place on 10 July this year. The test was a rehearsal of the flyby manoeuvres and operations, involving a spacecraft attitude flip and autonomous tracking by Rosetta of a virtual point corresponding to what would be the asteroid's position. The simulated time of closest approach was at midnight, with the test finishing a few hours later on the 15th.

The test of this delicate mission phase was successful and went very smoothly. The main activities during this flyby rehearsal were:

  • Slew to start attitude
  • Enter fine pointing accuracy phase (FPAP) attitude
  • Start of attitude flip manoeuvre
  • Navigation camera A set to asteroid tracking mode
  • End of attitude flip manoeuvre
  • Enter asteroid flyby mode (AFM)
  • Simulated closest approach (at 00:00 UT on 15 March)
  • End of AFM
  • Slew back to gyrostellar ephemeris phase (GSEP)
  • Enter GSEP attitude

Although this was a pure test of the spacecraft dynamics, it also provided an opportunity to perform monitoring and characterisation activities with few of the instruments. To this end the Philae lander and several of Rosetta's instruments were activated: OSIRIS, ROSINA, RPC and VIRTIS.

Spacecraft

Payload

ALICE
The instrument is currently OFF.

CONSERT
The instrument is currently OFF.

COSIMA
The instrument is currently OFF.

GIADA
The instrument is currently OFF.

MIDAS
The instrument is currently OFF.

MIRO
The instrument is currently OFF.

OSIRIS
The instrument is currently OFF. The instrument was activated during the Lutetia flyby test on DOY 073/074. On DOY 075 OSIRIS observed the object P/2010-A2.

ROSINA
The instrument is currently OFF. The instrument software was upgraded to v7.6 and successfully tested in multiple slots during the reporting period. The RTOF sensor is now declared operational. The instrument was also activated during the Lutetia flyby test on DOY 073/074.

RPC
The instrument is currently OFF. The instrument was activated during the Lutetia flyby test on DOY 073/074.

RSI
The ultra-stable oscillator is ON/muted since DoY 032/2010.

VIRTIS
The instrument is currently OFF. The instrument was activated during the Lutetia flyby test on DOY 073/074.

LANDER Philae
The instrument is currently OFF. The instrument was activated during the Lutetia flyby test. The software of the PTOLEMY instrument was updated in preparation of the twelfth payload check-out (PC12).

SREM
The instrument is ON with standard settings since DoY 032/2010.

Future Milestones

Few minor tests are planned before the start of the last active payload check-out phase in April 2010. Mission operations will be dedicated to the final tuning of the instruments for the flyby of asteroid Lutetia in July 2010 and for the deep space hibernation. The navigation campaign for the Lutetia flyby will begin at the end of May 2010.

Rosetta continues cruising towards asteroid Lutetia. The Rosetta spacecraft is configured in normal mode, in which it will nominally remain until the deep space hibernation entry in June 2011.


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Legal disclaimer
This report is based on the ESOC mission operations report, WOR #131. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.

Last Update: 1 September 2019
10-Jul-2020 11:01 UT

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