CAPS (the Comet and Asteroid Protection System)
Once again, though likely the first time for epi
This problem was analyzed in depth several years ago by a team of engineers from NASA Langley.
They concluded:
1) Use a Moon based LIDAR system for the detection of small dark impactors near the Earth
2) Use other Moon based instruments (radar, telescopes) for the detection of stuff on its way in from deep space
3) Use nuclear electric powered engines to deliver
a Solid State Heat Capacity Laser to the object for diversion by ablation