Recent analyses of the border regions between smooth and rugged sections of Itokawa indicate that jostling of the asteroid might be creating segregation between large and small rocks near the surface, like the Brazil nut effect.
In late 2005, Hayabusa actually touched down on one of the smooth patches, dubbed the MUSES Sea, and collected soil samples that are to be returned to Earth for analysis.
Hayabusa will start its three-year long return trip to Earth this month.
Computer simulations show that 500-meter asteroid Itokawa may impact the Earth within the next few million years.