Long-term predictability of orbits around the geosynchronous altitude

For a family of simulated geostationary, geosynchronous and super-geostationary orbits we compute the indicator called MEGNO in order to find out which orbits are chaotic and the timescale of their exponential divergence. A symplectic integrator of the Wisdom-Holman type was used for this purpose, with an integration span of 40 years. The results indicate that chaotic orbits exist only at the separatrix between geostationary libration and circulation and that they are relatively rare. The super-geostationary region seems to be entirely regular and quasi-periodic on the timescale of few decades.