Current Evolution of Meteoroids

Abstract

The observed mass distribution of meteoroids at 1 AU from the Sun is briefly reviewed in a survey that ranges over the bulk of the mass spectrum from micrometeoroids to meteorite parent objects. The evolution of meteoroids under the influence of collisions, planetary perturbations, the Poynting-Robertson effect and radiation pressure is then discussed.Most micrometeoroids are expelled from the solar system by radiation pressure shortly after their production as secondary ejecta during impact by larger objects or as dust ejected by comets. Particles that survive will eventually be swept out by the Poynting-Robertson effect.Meteoroids in the radio and photographic ranges are destroyed in collisions faster than they can be replaced by the production of secondary fragments during collisions between larger objects. The source of new particles needed to maintain the population of these meteoroids in a stationary distribution may be material expelled by comets.The survival of large objects is limited by gravitational scattering during close planetary encounters and by collisions as well, if they spend sufficient time in the asteroid belt. The observed radiation-exposure ages of chondrites are shown to be consistent with this model.