Asteroid Vesta rocked by mighty impacts

Better information on surface shape (topography) reveals that Rhea Silvia sits on top of an older impact crater. 

Rhea Silvia itself may be 2.5 billion years old. The equatorial trough system is also visible in this image.

The scale of the pummelling Asteroid Vesta has taken through its history is starting to become clear.

Analysis of data returned by the orbiting Dawn spacecraft shows this giant rock took a mighty double beating in its southern polar region.

One impact had long been recognised from images of the asteroid acquired by the Hubble telescope.

But Dawn's measurements indicate that Vesta was also hit much earlier in time in almost exactly the same location.

These two major impacts gouged out depressions hundreds of kilometres in diameter, and sent shockwaves rippling around the body.

Scientists are fairly confident that the deep system of troughs extending around Vesta's equator and northern hemisphere are fractures that opened up in the surface as a direct consequence of the southern bombardments.