[pavel_lishin]

I think comets are significantly harder to get a hold of; they're in long-period orbits, and changing their trajectories - or even catching up with them! - is significantly harder than catching something that circles the sun inside the orbit of Jupiter.

[Teever]

But could you use the hydrocarbons on the comet as fuel to change the orbit to a desirable one?

[JumpCrisscross]

Voyager, with with deflection nukes.