No. 131 - Asteroid Lutetia flyby test
06 April 2010 12:24
Report for Period 27 February to 26 March 2010
The 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.
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:
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.
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.