Stability maps for Phobos (Table 1) using an obliquity for Mars ε = 90°. From top to bottom, the initial eccentricity is e = 10⁻⁵, e = 0.015, e = 0.03, e = 0.045. Each column corresponds to the integration using different Hamiltonians: resonant Hamiltonian (left), interaction Hamiltonian (middle) and the full secular Hamiltonian (right). The color scale indicates the value of the quantity log₁₀ σ. The blue and green areas correspond to stable circulating trajectories, while the yellow, orange, and red ones correspond to chaotic motions. The black areas correspond to stable resonant regions, for which log₁₀ θ < −3.9.