Our species is so incredibly vulnerable to, and unprepared for, asteroid impacts.  While our ability to divert them is certainly lacking, what’s worse is our inability to reliably detect asteroids in time to possibly devise a means of deflecting or destroying them before they hit this planet.  Most recently, a 500m wide asteroid was detected a mere four days before it zoomed past our planet.  It wasn’t going to hit us, but was close enough to be of concern, but we never saw it coming.  Efforts are being made to improve asteroid detection, but considering the damage that they can and, historically, HAVE done to this planet, I fear we’re not doing as much as we should (and could).