Navigation campaign for the third Earth swing-by
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 gathered between 21 September and 1 October with the New Norcia ground station, the flight dynamics team have determined the initial solution for Rosetta's current predicted incoming trajectory in the B-plane. The predicted point and associated 3-sigma error ellipse are indicated here in black.
Progressively more accurate determinations of Rosetta's approach trajectory are obtained in the subsequent weeks leading up to the swing-by. See the related image for a close-up of the target region that includes the navigation results up to 15 October 2009.
A primary trajectory correction manoeuvre (TCM) is planned for 22 October. Three more slots are reserved for possible additional TCMs on 5, 12 and 13 November, but these may not all be needed.