Asteroid fission, binaries and the small main belt population

Using a Monte Carlo method we model the spin evo- lution of small Main Belt asteroids under the joint ef- fects of YORP and collisions. Our simulations allow us to estimate the fraction of asteroids undergoing ro- tational fission in different size ranges. When an aster- oid reaches its disruption spin limit we determine the outcome of its subsequent evolution based on accumu- lated statistics on their evolution based on numerical integrations (i.e., binary or ternary formation, binary disruption, etc..). Our aim is to predict the percentage of binary asteroids and their properties in the Belt, the number of objects like P/2010 A2 per year and the ef- fects of YORP-induced fission on the overall asteroid size distribution at the small size end.