Rubble Pile Asteroids

The moniker rubble pile is typically applied to all Solar System bodies >200 m and <∼10 km in diameter; in this size range, there is an abundance of evidence that nearly every object is bound primarily by self-gravity, with significant void space or bulk porosity between irregularly shaped constituent particles. The understanding of this population is derived from wide-ranging population studies of derived shape and spin, decades of observational studies in numerous wavelengths, evidence left behind from impacts on planets and moons, and the in situ study of a few objects via spacecraft flyby or rendezvous. The internal structure, however, which is responsible for the name rubble pile, is never directly observed but belies a violent history. Many or most of the asteroids on near-Earth orbits and those most accessible for rendezvous and in situ study are likely by-products of the continued collisional evolution of the main asteroid belt.