Study of mesosiderite zircons suggests Vesta was struck by a very large rock
(PHYSorg.com Space & Earth)

A team of researchers from Australia, Switzerland and Japan has found evidence suggesting that the asteroid Vesta was stuck by a very large rock approximately 4.5 billion years ago. In their paper published in the journal Nature Geoscience, the group describes their study of the asteroid and what they believe is material from it.