When released from the satellite, dust particles are subject to a number of forces. The planetary gravity usually dominates, but smaller debris are also vulnerable to a large array of nongravitational forces - solar radiation pressure, Lorentz force, circumplanetary plasma drag. The dynamics of dust grains in this complex force field were studied by many scientists, yielding a good understanding of the most important features of several circumplanetary dust complexes. A nontrivial interplay between the forces is problably best exemplified by the E ring of Saturn, an ethereal dusty sheet extending from 3 to 8 saturnian radii from the planet. Enceladus, a small icy moon of Saturn, is the likely source of the ring material.
Some people believe in the mechanism described above, others think of geysers or volcanoes.
Such a strange size distribution has been explained in a number of scientific papers. The idea is that the nongravitational forces acting on the grains are size-dependent, and the size of 1 micron turns out to be dynamically privileged. Only micrometer-sized particles can spread over a large region of the circumplanetary space and survive for a long time. The shadow of Saturn on its inner dense rings shows the direction of the incident sunlight. The ejected particles have finite lifetimes.