Lutetia flyby navigation campaign up to 7 June 2010
This plot shows the situation in the target plane for Rosetta's flyby of asteroid Lutetia on 10 July 2010. The target plane is a planar coordinate system centred on the asteroid and is used for targeting during this close flyby. The target relative position of Rosetta for the flyby is marked in green and is 3160 km from asteroid Lutetia (at the origin of the plot, direction indicated with arrow).
The plot shows two results in the target plane, both based on data up to 7 June 2010, but without any use of the optical data from Rosetta's on board cameras.
The black cross and associated 3-sigma error ellipse are almost identical to the plot that was based on the data up to 27 May. Small differences are due to the inclusion of the recent radiometric data since 27 May and of 10 more pairs of ground-based observations of the asteroid.
The blue cross and error ellipse are based on the same data set, but with a revised setting of the weighting factors applied to the individual observations that contribute to the overall solution. This new solution better takes into account the different accuracies of the individual observations. It also is much more consistent with the results obtained with the addition of the preliminary data from the optical navigation campaign by Rosetta's on-board cameras.
The blue cross lies only just within the black 3-sigma error ellipse boundary.
This new solution of Rosetta's projected position in the target plane is located 2621 km from Lutetia and 541 km from the target (marked green). The change from the old result for the predicted time of closest approach is, by contrast, very small - just 1.4 seconds later at 15:45:00.20 UTC (on 10 July). The 3-sigma uncertainty is now a little higher at 8.13 seconds.