Deflecting NEOs in route of collision with the Earth

We consider a small sample of known Near Earth Objects (NEOs), both asteroids and comets, with low Minimum Orbital Intersection Distance (MOID). Through a simple numerical procedure we generate slightly different orbits from this sample in such a way that these bodies will collide with the Earth at a specific epoch. Then we study the required change in orbital velocity (along track) in order to deflect these NEOs at different epochs before the impact event. The orbital evolution of these NEOs is performed through a full N-body numerical integrator. A comparison with analytical estimates is also performed in selected cases. Interesting features in the DeltaV Vs Time before impact plots are found; as a prominent result, we find that close approaches to the Earth before the epoch of the impact can make the overall deflection easier.