[meteorite-list] Rosetta - Asteroid Lutetia Flyby Test

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 8 Apr 2010 15:20:04 -0700 (PDT)
Message-ID: <201004082220.o38MK4GS024163_at_zagami.jpl.nasa.gov>

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=46783

Rosetta
No. 131 - Asteroid Lutetia flyby test
European Space Agency
06 Apr 2010

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.

*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.
Received on Thu 08 Apr 2010 06:20:04 PM PDT