Quote Originally Posted by georgeib View Post
I think maybe I lack imagination, because although I see this as a very cool proof of concept academic exercise, I don't see this ever practically working. Any asteroid or comet of sufficient mass to pose a threat to life on Earth, will not be dissuaded so easily. I'm not a physicist, but I do know how to do basic math, and it seems to me that the amount of mass or force necessary to significantly alter a massive object's path is going to be much more than we can muster.

In my mind, it's not that we are limited by current technology, per se, rather that the laws of physics and our ability to bring enough mass to bear are the limiting factors. I can't help but compare us to a moth trying to alter the trajectory of a fully loaded 18 wheeler traveling at 100 mph by smashing itself into the windshield. In theory, that moth's mass DID alter that truck's trajectory, but in reality it may as well not have for all the difference it would make.

The big take away from the video seems to be that they can actually hit the asteroid at all. In itself an amazing accomplishment. Very cool.
They will need to incorporate a payload to even begin to address threats, this was just a dry run.

Right now the biggest known risk is 99942 Apophis which in 2006 was seen as possibly on target for a direct impact on April 13, 2036 and yes that is a Friday. It has since been revised and there was an earlier date of concern for April 13, 2029 which is not currently believed to be a threat but this one could easily be a problem in the immediate future even though a direct impact has been ruled out by the JPL.

We have had more than a few close ones that passed within half the distance to the moon, thankfully most of them have been pretty small compared to the ones we worry about. Asteroid 2012 DA14 flew by very close in 2013.