Planetary Science Seminar spring-2012

Small asteroids (< 10 km) can evolve into all classes of observed near-Earth asteroid (NEA) binaries as well as observed, non-collisional families of asteroids. Solar radiation is the primary driver of this evolution. The YORP effect, an effective torque driven by solar and thermal radiation, can rotationally accelerate asteroids towards the a rotational disruption speed limit, where the gravitational accelerations holding the body together are overcome by the centrifugal accelerations pulling the body apart. There is a specific speed at which two coherent sections of the steroid may go into orbit about each other. From this rotational fission event, a chaotic binary system is created and will evolve according to spin-orbit interactions, solar gravitational tides, the YORP effect, mutual body tides, and once a member of the binary is tidally locked,the binary YORP effect. Which of these forces is dominant will determine the evolutionary path of the asteroid system and what observable, long term state it will occupy, including the doubly synchronous binaries, singly synchronous binaries, asynchronous binaries, contact binaries, asteroid pairs or more exotic classes.