Asteroid defense: any feasible ideas or we are just doomed theoretically ?

[krispos42]

5. the biggest nuclear warhead we can build...

...donated in a crater of the asteroid.

The crater would focus the blast, creating a brief but very strong push in one direction.

If you wait until the crater is in the right orientation, you could speed up or slow down the asteroid slightly, resulting in a near-miss months or years down the line. Same thing with a sideways shove.

Multiple donations could be made to occur. The blast would be on the surface so it's unlikely to break the rock up, but a few nudges plus time and distance could turn a hit into a miss.