Times of inspiralling for interplanetary dust grains

There are uncharged spherical dust particles interacting with solar electromagnetic radiation moving in the gravitational fields of the Sun and the Earth. The Earth is supposed to be moving in a circular orbit, and the effect of solar electromagnetic radiation is given by the Poynting-Robertson effect. The time of particle inspiralling toward the Sun is analysed for the pure Poynting-Robertson effect and in order to include the gravitational effect of the Earth. It is shown that the exterior mean-motion orbital resonances with the Earth may increase the time of spiralling into the Sun by 50 per cent, compared with the case of neglecting the gravitational effect of the Earth, for eccentricities smaller than 0.8. The result holds for particles from 1 mu m to tens of mu m in radii.