Dynamical models of Kuiper belt dust in the inner and outer solar system

We report several results related to the dynamical evolution of dust produced in the Kuiper belt (KB). We show that its particle size frequency distribution in space is greatly changed from the distribution at production, as a result of the combined effects of radiation forces and the perturbations of the planets. We estimate the contribution of KB dust to the zodiacal cloud by calculating the radial profile of its number density near the ecliptic. We also study the contribution of KB dust to the population of interplanetary dust particles (IDPs) collected at Earth, by calculating geocentric encounter velocities and capture rates. Our models show, in contrast with previous studies, that KB dust grains on Earth-crossing orbits have high eccentricities and inclinations and, therefore, that their encounter velocities are similar to those of cometary grains and not asteroidal grains. We estimate that at most 25% in number of captured IDPs have a cometary or KB origin; the KB contribution may be as low as 1%-2%. We present the velocity field of KB dust throughout the solar system; this, together with the number density radial profile, is potentially useful for planning spacecraft missions to the outer solar system.