 These troughs are thought to be large-scale graben resulting from the impacts that created Rheasilvia and Veneneia craters, respectively.They are some of the longest chasms in the Solar System, nearly as long as Ithaca Chasma on Tethys.The troughs may be graben that formed after another asteroid collided with Vesta, a process that can happen only in a body that, like Vesta, is differentiated.