Selparis

In 2007, NASA launched the Dawn spacecraft bound for the solar system’s second largest asteroid – Vesta. It entered the orbit of Vesta in July of 2011 and will continue in orbit until August of this year, after which it will be bound for the largest asteroid – Ceres – which it will reach in 2015.

Vesta - Courtesy of NASA

The press conference about Dawn’s findings today centered on Vesta’s Rheasilvia Crater and its age. Rheasilvia is a massive impact crater with a central peak – Rheasilvia Mons – which ranks as the tallest known mountain in the solar system (with Olympus Mons a close second). The material ejected by the impact amounts to about 250,000 cubic miles, and makes up around six percent of the material in the asteroid belt, including the Vesta family of asteroids. Some of it has even reached Earth, so that scientists knew what to look for when launching this mission to Vesta. Evidence now clearly indicates that the impact occurred a billion years – much more recently that the majority of impacts on the Moon, which occurred over three billion years ago. According to the researchers in the conference, this puts constraints on ideas about solar system dynamics – the way objects have moved around the solar system since its formation.

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