Earth swingby navigation campaign up to 26 October 2009
On 13 November 2009, Rosetta will perform its third Earth swing-by. This plot shows the target point (green) for Rosetta's approach relative to the Earth in the B-plane. The B-plane is a planar coordinate system that allows targeting during a gravity assist.
The target is not the point of closest approach. Instead this virtual point corresponds to what would be Rosetta's miss distance if the Earth had no gravity. (It is the point through which the spacecraft's incoming hyperbolic asymptotic velocity vector passes, which is perpendicular to this B-plane).
Based on radiometric data from the navigation campaign the Rosetta flight dynamics team has determined solutions for the spacecraft's predicted incoming trajectory in the B-plane. Successively more accurate determinations of the predicted point relative to the target were obtained using data up to 1 October (black), 8 October (red) and 15 October (orange). For each date the associated 3-sigma error ellipse is also given.
A trajectory correction manoeuvre (TCM) was successfully performed on 22 October, which moved the predicted point in the B plane by 111 km (purple arrow in the plot) to less than 1 km from the target point.
|Evolution of the predicted offset from the target, in this plot:
|Result using data up to and including 1 October.
The offset from the target in the B-plane = 124 km
|Result using data up to 8 October.
The offset from the target in the B-plane = 112 km
|Result using data up to and including 15 October.
The offset from the target in the B-plane = 108 km
|Result using data up to 19 October.
The offset from the target in the B-plane = 111 km
|Result using data up to 26 October.
The offset from the target in the B-plane = <1 km