Status Report

Rosetta in Good Health

By SpaceRef Editor
March 6, 2004
Filed under , ,
Rosetta in Good Health

Launch Summary

Ariane 5 Flight 158 lifted off right on-schedule at 07:17:51 UTC on 2 March
carrying with it the Rosetta spacecraft on the start of its 10 year journey
to comet Churyumov-Gerasimenko.

The solid boosters separated as expected at 07:20 UTC, followed 50 seconds
later by the fairing. The first stage burn continued until 07:27 UTC and
injected the EPS and Rosetta into a coast orbit. This was the first occasion
that an Earth escape trajectory and a large delay until ignition of the
upper stage has been flown by an Ariane 5 launch vehicle and the progress of
the flight was monitored with mounting tension in the ESOC control centre.

The ignition of the EPS occurred 107 minutes after launch at 09:14 and was
monitored from a ground station in Hawaii until the vehicle moved out of
contact. Contact was made again from the Galliot station in Kourou and at
09:32:36 Arianespace announced the separation of Rosetta. The achieved orbit
proved to be near perfect.

There was great joy and excitement in the ESOC control centre when the ESA
Kourou ground station acquired the TM signal from Rosetta one minute later
at 09:34. The spacecraft status was as expected and the automatic separation
sequence was seen to be in progress. The venting and priming of the
propulsion system was completed at 9:44.

Activation and Checkout

The initial spacecraft spin rate reduction and Sun acquisition phase
proceeded very smoothly, and this was followed by the deployment of the two
solar array panels, which was completed at 10:11. The separation sequence
was completed with Sun reacquisition.

2 March 2004

  • 10:34 Uplink of the first telecommands from the Kourou station Early Orbit Phase
  • 11:25 Both star trackers switched on for first check
  • 13:15 Both star trackers switched on to be used for attitude control
  • 13:51 Spacecraft enters Safe Hold Mode
  • 14:23 Reaction wheels switched on
  • 14:47 Spacecraft commanded into Normal Mode

The launch locks of the Lander Philae have been released successfully at the
end of the first ground station pass. Philae now remains firmly attached to
the spacecraft by the cruise latches until its release at the comet.

3 March 2004

  • 00:34 The High Gain Antenna was deployed, starting with firing the pyros of the launch locks. This was followed by 3 rotations, first in elevation, then in azimuth, and finally a combined azimuth and elevation movement, which brought the 2.2 m dish in the Earth pointing position. 09:34 The first trajectory correction manoeuvre was a test manoeuvre of 1 ms-1. The spacecraft was slewed to the required attitude in preparation for the 7 minutes burn.
  • 11:49 Start of 7 minutes burn.
  • 14:09 The attitude orbit control systems performed flawlessly throughout the manoeuvre and the spacecraft was back in its normal mode.

Due to the excellent spacecraft performance and the good progress of planned
activities, it is anticipated to advance some of the planned platform and
payload commissioning.

This completed a very successful first phase of the mission. The spacecraft
has behaved very much as expected. Both the Rosetta spacecraft and ground
segment continued to perform excellently.

Orbit Trajectory

The spacecraft is travelling at a relative speed of 15 000 kmh-1 away from
the Earth and it has passed a distance of 700 000 km. The specialists at
ESOC have completed the initial orbit determination and confirmed the
excellent injection to orbit by the Ariane 5 launch vehicle. The resulting
orbital elements are as follows:

EPOCH (UTC) 2004/03/02 09:32:36 (separation from Ariane 5)

  • The Earth Equatorial J2000.0 State and Elements WRT Centre of the Earth
  • Position (km) X -3800.385690
    • Y -6686.243272
    • Z 764.805818

  • Velocity (kms-1) Xdot 6.740760
    • Ydot -8.376383
    • Zdot 0.312135

  • Semi Major Axis (km) -31756.626407
  • Eccentricity 1.213208
  • Inclination (°) 5.697642
  • Ascending Node (°) 145.741025
  • Argument of Pericentre (°) 55.326314
  • True Anomaly (°) 39.296396
  • Pericentre Distance (km) 6770.767019
  • Vinfinity (kms-1) 3.542841
  • Vinfinity Right Ascension (°) 346.486802
  • Vinfinity Declination (°) -2.024067
  • NOTE: All times are in UT

    SpaceRef staff editor.