Mechanism underlying size-sorting of rubble on asteroid Itokawa revealed

In 2005, the Hayabusa spacecraft developed by the Japan Aerospace Exploration Agency (JAXA) landed on Itokawa, a small near-Earth asteroid named after the famous Japanese rocket scientist Hideo Itokawa. The aim of the unmanned mission was to study the asteroid and collect a sample of material to be returned to Earth for analysis. Contrary to scientific predictions that small asteroids are barren nuggets of rock, photographs taken by the Hayabusa spacecraft revealed that the surface of Itokawa is...