Scientists don't know how Vesta survived the impacts that destroyed so many other objects in the Main Asteroid Belt, which lies between Mars and Jupiter. Vesta does bear the scars of brutal beatings, including a 290-mile diameter impact crater that left basin walls three times higher than Mount Everest.
"There were several large impacts that have tried to destruct Vesta," Reddy told Discovery News. "We don't know whether its general structure has something to do with the way it has been protected and still intact today. We're not sure if it has something to do with Vesta's location. We have a family of objects (meteorites) that actually are pieces of Vesta ... so we know that some pieces have been taken off. The question is why has it remained intact? I don't know."
After a year of study at Vesta, Dawn is scheduled to move on to the largest object in the region, the dwarf planet Ceres.
Image: This image using color data obtained by the framing camera aboard NASA's Dawn spacecraft shows Vesta's southern hemisphere in color, centered on the Rheasilvia formation. Rheasilvia is an impact basin measured at about 290 miles (467 kilometers) in diameter with a central mound reaching about 14 miles (23 kilometers) high. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA