Hows that interstellar space travel workin out for ya?
On the other hand, it's pretty amazing that Voyager has got to where it is simply by coasting with a couple of gravity assist boosts from Jupiter and Saturn. Having any kind of propulsion would totally change the ballgame.
Would propulsion gets you going faster than 10 miles a second? (I’m no rocket surgeon!) Its hard to beat a gravity swing around Jupiter. Even with propulsion, how fast can you go before vibrations tear you apart or you hit something, ANYTHING, at that speed? (Now we need warp drive, deflectors.....)