Violent Asteroid Crashes Shaped Protoplanet Vesta's Odd Interior

Astronomers have recreated two cataclysmic collisions that sculpted the interior of the giant asteroid Vesta, revealing that the so-called protoplanet may actually have a crust far thicker than expected.

The new model is based on computer simulations of separate collisions between the asteroid Vesta and a pair of 20-mile-long (32 kilometers) rocks within the last billion years. The results suggest that the cosmic impacts caused Vesta's crust to melt and then re-form, making its crust thicker than can be explained by typical rock layering, scientists said.

The collisions carved two large impact craters into the surface of Vesta. The oldest, Veneneia, formed approximately 2 billion years ago. With a diameter of 245 miles (395 kilometers), the crater covers almost three-fourths the diameter of Vesta's equator.

Almost a billion years later, another large body scooped out an even broader chunk. The resulting crater Rheasilvia is 314 miles (505 km) long. Spanning 90 percent of Vesta's diameter, it is one of the largest craters in the solar system.

more here: http://www.space.com/19767-asteroid-vesta-violent-collision-history.html