The Exoatmospheric Kill Vehicle

Hapster writes " Raytheon has developed the most expensive weapon ever. This ICBM killer hones in on an oncoming missile and, like a bullet hitting another bullet, hopes to smash into it before it smashes into us. " On a sheer technology level, devices like this are some of the most intrinsicly interesting around, although I'm still not quite sure who's the enemy.