Relative position of Rosetta and Steins in target plane - 4 September 2008
This plot shows the situation in the target plane for the Rosetta fly-by of asteroid Steins. It is based on the optical navigation data as well as all radiometric data (spacecraft tracking) and ground-based astrometric data up to and including 4 September 2008, except that the NAVCAM data from 4 September are not yet included.
Ellipses indicate 3-sigma error circles around Rosetta's determined positions (crosses) relative to asteroid Steins (at the origin, direction indicated with arrow). The target relative position of Rosetta for the Steins fly-by is marked in green and is 800 km from asteroid Steins.
The plot shows four colour-coded positions, each derived with progressively more input from the optical navigation campaign with Rosetta's on-board cameras.
|Orange||The orange cross and associated dashed 3-sigma error ellipse is the solution from 25 August (see related images)|
|Blue||The blue cross and associated 3-sigma error ellipse is the solution from 1 September.|
|Black||The black cross and associated dashed 3-sigma error ellipse is the solution from 3 September.|
|Purple||The purple cross and associated dashed 3-sigma error ellipse is the solution from 4 September, after the TCM.|
A Trajectory Control Manoeuvre (TCM) was successfully performed in the morning of 4 September, with a delta-V of 11.8 cms-1, see also the status report linked from the right-hand menu. The nominal shift of Rosetta's relative position in the target plane is indicated with the pink line.
The latest pre-fly-by determination given here (purple, 4 September 2008) includes the processing of optical measurements from 5 OSIRIS images taken after the TCM. Rosetta's final projected relative position was 1.9 km from the target, with the spacecraft expected to pass asteroid Steins at about 800.7 km (purple cross).
The dashed red line running through the target point shows the contour 800 km from Steins.