“Planetary protection supporters have touted the ability of ARM to demonstrate a method of altering an incoming planetoid’s path by means of a “gravity tractor” technique – using the mass of the spacecraft and a sizable boulder collected from the asteroid to create a gravitational field sufficient to ‘tug’ the asteroid. Simulations suggest that it is possible to deflect an incoming body without the need to use a more direct, and potentially less effective, means of diversion – such as a nuclear detonation or an impactor.”
If you think nuclear weapons are destructive, wait until we can deflect an asteroid or two to Earth! Craters the size of counties!
The idea is to redirect the asteroid AWAY from Earth.
Conventional wisdom (in the academic-government-NASA-research institutes) forbids, of course, the use (or even thought of!) nuclear weapons to blow parts of the inbound comet/asteroid into smaller pieces that might just NOT hit the earth at all......
Hits that big are as bad as a general nuclear conflagration. Very few humans survive, in the long run.