Every so often scientists announce that a large space rock or asteroid will pass within a couple of hundred thousand kilometres of Earth. The tabloid press proclaim a near miss and that we were lucky to dodge Armageddon. Headline grabbing stuff it may be, but the truth of the matter is, that it is only a matter of time until the Earth experiences an impact event when one of these asteroids makes it through our atmosphere and explodes with tremendous force creating significant damage.