Orbit perturbations in the vicinity of an active cometary nucleus

Orbit stability in the vicinity of an active cometary nucleus is described. Modelling of the nucleus, cometary jets, as well as their distribution on the surface, is also discussed. A simulation is developed to model the perturbative accelerations caused by non-spherical gravitational effects and cometary gas jets during the rendezvous phases of the ESA Rosetta mission. Results show that the effects of the neutral coma on spacecraft operations are more serious than previously thought and must be taken into account when planning a rendezvous mission to a comet. Because of the small comet mass the system is very unstable and changes in any parameter may result in a very different set of spacecraft trajectories.