  We have carried out a numerical investigation of the coupled gravitational
and non-gravitational perturbations acting on Earth satellite orbits in an
extensive grid, covering the whole circumterrestrial space, using an
appropriately modified version of the SWIFT symplectic integrator, which is
suitable for long-term (120 years) integrations of the non-averaged equations
of motion. Hence, we characterize the long-term dynamics and the phase-space
structure of the Earth-orbiter environment, starting from low altitudes (400
km) and going up to the GEO region and beyond. This investigation was done in
the framework of the EC-funded "ReDSHIFT" project, with the purpose of enabling
the definition of passive debris removal strategies, based on the use of
physical mechanisms inherent in the complex dynamics of the problem (i.e.,
resonances). Accordingly, the complicated interactions among resonances,
generated by different perturbing forces (i.e., lunisolar gravity, solar
radiation pressure, tesseral harmonics in the geopotential) are accurately
depicted in our results, where we can identify the regions of phase space where
the motion is regular and long-term stable and regions for which eccentricity
growth and even instability due to chaotic behavior can emerge. The results are
presented in an "atlas" of dynamical stability maps for different orbital
zones, with a particular focus on the (drag-free) range of semimajor axes,
where the perturbing effects of the Earth's oblateness and lunisolar gravity
are of comparable order. In some regions, the overlapping of the predominant
lunisolar secular and semi-secular resonances furnish a number of interesting
disposal hatches at moderate to low eccentricity orbits. All computations were
repeated for an increased area-to-mass ratio, simulating the case of a
satellite equipped with an on-board, area-augmenting device.
