25143-Itokawa

A Japanese spacecraft has provided one of the best arguments yet in favor of a conception of asteroids which was pioneered by PSI (Planet Science Institute) scientists Don Davis and Clark Chapman in the late 70's. The evidence comes in startling closeup pictures of the tiny asteroid 25143-Itokawa, photographed by the Japanese Hayabusa spacecraft during a two-month encounter in late 2005. The asteroid illustrates the concept of a "Rubble-Pile" asteroid, which is composed of a mixture of boulders and dust gravitationally bound together.
The scientific results, recently highlighted in the journal Science, show that, unlike other asteroids recently imaged by spacecraft, which are mostly rounded and potato-like, dotted by craters, and with a few scattered boulders on the surface, Itokawa appears to be composed of massive splinter-like boulders protruding from a matrix of smaller fragments.
The largest boulders sticking out of the body appear to be some tens of meters across.

The Hayabusa science team includes PSI scientists Paul Abell and Bob Gaskell, and PSI affiliate scientists Hirdy Miyamoto and Faith Vilas.