[MrB]

It seems like a relatively small change in velocity now might result in a change of orbit large enough to have this totally miss the earth.

I have a bit of a problem with this idea at this point. They don't know if it will hit, come close, or miss us by a LARGE distance. What happens if they nudge it INTO the path of the earth by accident?

[Salgak]

That problem is fairly straight-forward Newtonian physics. Once you establish what the orbit is with sufficient precision. You then can model where and how to nudge it. The obvious place to do so is on it's closest approach to the sun: this is referred to as a "gravity well manuever": using the impulse at the body's deepest foray into a given gravity field. . .

[harpseal]

At this point the orbit is not well enough known to even try but if the orbit is going to eventually hit this planet then we need to consider remedial measures. Just what those remedial mesures would be is an open question. They could include a Solar Sail, Mass driver, nuke, rocket, and some other options. At present we have 17 years to examine the problem and devise a solution if needed.