  The solar system is dusty, and would become dustier over time as asteroids
collide and comets disintegrate, except that small debris particles in
interplanetary space do not last long. They can be ejected from the solar
system by Jupiter, thermally destroyed near the Sun, or physically disrupted by
collisions. Also, some are swept by the Earth (and other planets), producing
meteors. Here we develop a dynamical model for the solar system meteoroids and
use it to explain meteor radar observations. We find that the Jupiter Family
Comets (JFCs) are the main source of the prominent concentrations of meteors
arriving to the Earth from the helion and antihelion directions. To match the
radiant and orbit distributions, as measured by the Canadian Meteor Orbit Radar
(CMOR) and Advanced Meteor Orbit Radar (AMOR), our model implies that comets,
and JFCs in particular, must frequently disintegrate when reaching orbits with
low perihelion distance. Also, the collisional lifetimes of millimeter
particles may be longer (>10^5 yr at 1 AU) than postulated in the standard
collisional models (10^4 yr at 1 AU), perhaps because these chondrule-sized
meteoroids are stronger than thought before. Using observations of the Infrared
Astronomical Satellite (IRAS) to calibrate the model, we find that the total
cross section and mass of small meteoroids in the inner solar system are
(1.7-3.5)x10^11 km^2 and 4x10^19 g, respectively, in a good agreement with
previous studies. The mass input required to keep the Zodiacal Cloud (ZC) in a
steady state is estimated to be 10^4-10^5 kg/s. The input is up to 10 times
larger than found previously, mainly because particles released closer to the
Sun have shorter collisional lifetimes, and need to be supplied at a faster
rate.
