ESA Science & Technology - No. 37 - Report on Earth Flyby

The spacecraft was gradually configured for the Earth swing-by, including activation of the fourth Reaction Wheel on 25 February, switching of the RF link from X-band to S-band on 27 February, and on 2 March from High Gain to Low Gain antenna, etc.

On 1st March the first payload instruments were activated: RPC and Lander ROMAP. These were followed by MIRO and VIRTIS on 4 March. SREM was always active in the background. Lander/CIVA was operated for three hours around Earth closest approach.

The Earth swing-by operations included various open-loop tracking tests with the Navigation Cameras, using the Moon as target, on 4 March. All operations were successful, with the exception of a problem in configuring the link between Camera B and the on-board Mass Memory, preventing pictures taken by this camera to be stored on-board.

After closest approach with the Earth (at an altitude of 1954 Km at 22:09 on 4th March), the spacecraft was commanded at 01:00 on 5 March into Asteroid Flyby Mode, using the Navigation Camera pointed on the Moon to control the attitude. This was the first and only in-flight test opportunity for this mode, which will be used operationally during the actual flyby of the asteroids Steins in 2008 and Lutetia in 2010. The test lasted 9 hours and was fully successful.

After the end of the test the spacecraft was pointed back to Earth to allow payload instruments and the Navigation Cameras to take Earth pictures from a rapidly growing distance of about 250 000 km.

After the swing-by the RF link was configured back to S-band on High Gain Antenna on 6 March, and the new Earth pointing attitude initiated on 8 March. On the payload side, VIRTIS was switched off on 5 March, MIRO, Lander ROMAP and RPC on 7 March. ALICE was activated in various slots on 8 and 9 March. The downlink of all generated science data was completed on 10 March.

At a Science Working Team meeting at ESOC on 8 and 9 March the Rosetta Principal Investigators presented preliminary results of their instruments' operations during this phase. The overall performance of the instruments was very good and good scientific and calibration data could be collected both by the remote sensing and the plasma instruments active around Earth swing-by.

Daily New Norcia passes were taken, and as from 27 February priority of coverage was returned to Rosetta until 10 March, in support of the orbit manoeuvres and to increase tracking data recovery for precise orbit determination. For the same reason, daily DSN passes were taken (typically 4 hours each).

Science Results

Target: Earth Date: 5 March 2005 Time: 13:08 UTC F.O.V.: 4 x 4 degrees
Target: Earth Date: 5 March 2005 Time: 12:47 UTC F.O.V.: 4 x 4 degrees
Target: Earth Date: 5 March 2005 Time: 12:47 UTC F.O.V.: 4 x 4 degrees
Target: Earth Date: 5 March 2005 Time: 12:45 UTC F.O.V.: 4 x 4 degrees
Target: Moon Date: 4 March 2005 Time: 22:08 UTC F.O.V.: 5 x 5 degrees
Target: Earth & Moon Date: 4 March 2005 Time: 22:06 UTC F.O.V.: 5 x 5 degrees
Target: Earth Date: 4 March 2005 Time: 21:59 UTC F.O.V.: 5 x 5 degrees
Target: Earth Date: 4 March 2005 Time: 21:57 UTC F.O.V.: 5 x 5 degrees
Target: Moon Date: 4 March 2005 Time: 15:10 UTC Distance to Target: 428 061 km

Activities

The table below shows a chronology of the main activities in the reporting period (only active passes shown):

At the end of the last New Norcia pass in the reporting period (DOY 070) Rosetta was at 2.78 million km from the Earth. The one-way signal travel time was 9.2 sec.