Escape of particles orbiting asteroids in the presence of radiation pressure through separatrix splitting

We study the motion of grains in orbit around asteroids under the influence of radiation pressure originating in the flux of solar photons. Of interest is the possibility of initially bound grains becoming unbound and leaving the vicinity of the asteroid. The analysis extends the two-degree-of-freedom results of (Dankowicz, 1995) to three-degree-of-freedom motions. In particular, we use a Melnikov-type approach for finding transversal points of intersection between high-dimensional perturbed stable and unstable manifolds. As a consequence, the system is shown to be nonintegrable and the resulting homoclinic tangles are suggested as a means for phase space transport along resonance layers, so-called Arnol'd diffusion. We discuss the implications of the diffusion on the depletion of asteroid-bound particles and attempt to estimate the diffusion rate for physical comparison. For particular values of physical parameters the time scale is shown to be on the order of hundreds of orbital revolutions of the asteroid around the sun.