KUIPER BELT DUST GRAINS AS A SOURCE OF INTERPLANETARY DUST PARTICLES

The recent discovery of the so-called Kuiper belt objects has prompted the idea that these objects produce dust grains that may contribute s ignificantly to the interplanetary dust population. In this paper, the orbital evolution of dust grains, of diameters 1 to 9 mu m, that orig inate in the region of the Kuiper belt is studied by means of direct n umerical integration. Gravitational forces of the Sun and planets, sol ar radiation pressure, as well as Poynting-Robertson drag and solar wi nd drag are included. The interactions between charged dust grains and solar magnetic field are not considered in the model. Because of the effects of drag forces, small dust grains will spiral toward the Sun o nce they are released from their large parent bodies. This motion lead s dust grains to pass by planets as well as encounter numerous mean mo tion resonances associated with planets. Our results show that about 8 0% of the Kuiper belt grains are ejected from the Solar System by the giant planets, while the remaining 20% of the grains evolve all the wa y to the Sun. Surprisingly, the latter dust grains have small orbital eccentricities and inclinations when they cross the orbit of the Earth . This makes them behave more like asteroidal than cometary-type dust particles. This also enhances their chances of being captured by the E arth and makes them a possible source of the collected interplanetary dust particles; in particular, they represent a possible source that b rings primitive/organic materials from the outer Solar System to the E arth. When collisions with interstellar dust grains are considered, ho wever, Kuiper belt dust grains around 9 mu m appear likely to be colli sionally shattered before they can evolve toward the inner part of the Solar System. The collision destruction can be applied to Kuiper belt grains up to about 50 mu m. Therefore, Kuiper belt dust grains within this range may not be a significant part of the interplanetary dust c omplex in the inner Solar System. (C) 1996 Academic Press, Inc.