Gravitational focusing of the wind in the satellite’s co-moving frame in the approximation of free-particle motion. The thin black lines show asymptotes of the Keplerian hyperbolic trajectories. Owing to an aberration of the initial velocities, the trajectories with the same impact-parameter in the orbital plane (x,y) (red in the electronic version) reach the x-axis closer to the gravitating body (placed in the coordinate centre) than those in (x,z)-plane (blue lines). The particles moving out of these planes (violet lines) collide mutually in the (x,z)-plane before reaching the x-axis