The threat raised by space debris has vivified long-term studies of terrestrial
orbits. To apprehend the motion on long time scales, the Astrodynamics
community has translated, deployed and adapted many tools coming from
Dynamical System theory and Celestial Mechanics. During this seminar, I will
review and discuss some aspects of the long-term dynamics of terrestrial
orbits, especially in the range of medium altitude. In particular, I’ll reveal
a manifold structure in a 3 degrees-of-freedom Hamiltonian system physically
representative of the dynamics of navigation satellites. Long-time properties
of the system are explained in terms of the possible normally hyperbolic
manifold structure and the associated stable and unstable manifolds regulating
transport properties. Those transport properties could be appealing for end-
of-life strategies based on manifolds dynamics.