Delivery of asteroids and meteorites to the inner solar system
Two major models of asteroid/meteorite demographics are described and reviewed critically: the collisional model of Greenberg and Chapman (1983), and the orbital evolution model of Wetherill (1985). It is shown that each of the two models tends to gloss over the central processes in the other and tends to ignore (and to some degree violate) the key observables that constrain the other model. The uncertainties that prevent definite acceptance of any particular model for the delivery of asteroidal material to the earth are described.