Mars Express Navigation for Beagle 2 Separation and Mars Orbit Insertion

The navigation of Mars Express (MEX) is described, concentrating on the orbit determination, although some aspects of trajectory optimisation are mentioned. The main emphasis is on the critical phase of Mars approach, Beagle 2 (lander) release, and Orbit Insertion (MOI). Some features of the spacecraft dynamics are summarised and an example presented of the quality of the conventional radiometric tracking data. These were augmented by delta differential one-way range (∆DOR) data points derived from NASA Deep Space Network (DSN) DOR measurements. Their benefit for reducing targeting uncertainties is demonstrated.