Spacecraft attitude angle rates during fly-by of asteroid Steins
For the fly-by of asteroid Steins on 5 September 2008, the Rosetta spacecraft performed an attitude flip manoeuvre between 40 and 20 minutes before closest approach to the asteroid, after which the spacecraft was kept pointing at the asteroid though autonomous tracking and attitude control by an on-board navigation camera (NAVCAM A).
A schematic diagram illustrating the manoeuvres during the asteroid fly-by is given below, with time running from left to right. The spacecraft's attitude is indicated by its +Z axis (toward position of asteroid Steins - red marker) and +X axis (blue). The Y axis is through the solar arrays, which is perpendicular to the diagram's view (except during the attitude flip where the spacecraft span around the Z axis through 180 degrees).
The top graph shows the angle rates (in degrees per second) for the Rosetta spacecraft's three main axes between about 17:44 UT and 19:14 UT on 5 September 2008. Clearly visible are:
- The attitude flip manoeuvre about the Z-axis (green)
- Rotation about the Y-axis (red) as the spacecraft autonomously tracked asteroid Steins around closest approach
At closest approach the Rosetta spacecraft flew by asteroid Steins at a distance of 800.7 km and with a relative velocity of 8.6 kms-1.