The television pictures on board were designed to begin operating when the rocket came within 2, 500 miles (4, 023km) of the lunar surface - 40 minutes before impact - and then send an image of the Moon backtoEarth every 13 seconds.
During the simulation of the 2029 encounter with Apophis, it became clear that under the right conditions, the asteroid would be deflected into a new orbit that would send it backto threaten Earth exactly seven years later.