Featured image for August 2007:
A "Rubble-pile" Asteroid
This image of asteroid 25143 Itokawa, photographed by the Japanese Hayabusa spacecraft during a two-month encounter, September-December, 2005, is suggestive of the "rubble-pile" conception of asteroid formation and structure. The scientific results of the mission are highlighted in the June 2, 2006 special issue of the journal Science, and show morphology unlike that seen in other asteroids, 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 larger matrix of smaller fragments and dust. The largest bolders sticking out of the body appear to be some tens of meters across. The title of the lead article from the Hayabusa team, by Fujiwara and 21 other authors, refers to "The Rubble-Pile Asteroid Itokawa."
Image courtesy ISAS/JAXA Japanese space agency.