Poppa Chris : What about a fully gimbled parabolic reflector on the rear which could use the solar winds to assist in propultion, of course you would need to slave that to a microprocessor controled star gazer and inertial corrected navagational guidence system capable of remote access by mission control. The way I see it the faster you travel away from the sun the fewer particles from the sun you would need to deflect. However I don't think they could ever catch or out run the solar winds, that would be really fast ( some estimates near the sun range at 500k miles per hr. to about one million miles per hr.). Just an opinion.