Abstract

My talk will focus on the evolution of a rubble pile asteroid subject to an increasing spin rate from the YORP effect. As the total angular momentum of the body increases, the system can pass thresholds where a different configuration or distribution of its constituents can have a lower energy configuration, setting up the preconditions for a "landslide". If the spin rate continues to increase, the rubble pile components can fission, often at spin rates considerably lower than the surface disruption rate, and the system can become a proto-binary. The stability of this proto-binary is controlled by its free energy, which is a function of its shape morphology. For irregularly shaped bodies we find that many of these will have a positive free energy, meaning that they can escape from each other with very slow relative escape speeds. The mechanical and dynamical considerations involved with these issues will be presented and discussed.