Vesta is the only remaining instance of the unique substance that came together to shape the stony planets, like Earth and Mars, some 4.6 billion years ago. According to Carol Raymond, Dawn's deputy principal investigator from NASA’s Jet Propulsion Laboratory in Pasadena, California, this mission has been an impressive achievement.
This melting would contain led to separation, to denser resources like iron falling to the asteroid's centre. The model of craters on Vesta has permitted the Dawn team to age Rhea Silvia and Veneneia. The previous was formed about a billion years ago. The latter was dug out by an impact about two billion years ago. The researchers believe Vesta formed within two million years of the first solids coming together in the Solar System, before the planets we know today were assembled.