Well, rocket technology hasn't really advanced all that much since Voyager was launched. We could certainly send a faster probe out by spending more money to bu

Well, rocket technology hasn't really advanced all that much since Voyager was launched. We could certainly send a faster probe out by spending more money to build a bigger rocket. On the other hand, they could have done so back then, as well. On the other hand, Voyager picked up an awful lot of its speed not from its initial launch but from slingshotting around the various planets it visited -- essentially picking up some free energy at the cost of infinitesimally perturbing the planet's orbit. If our goal was to send a probe out of the solar system as quickly as possible, we might be able to do a better slingshot than was done back then. On a third hand, Voyager 2 benefited from a rather fortuitous arrangement of planets which enabled it to visit all four giant planets and presumably pick up some momentum from each. This kind of configuration only comes around once every few centuries so if we launched it now then it would have to miss some planets. I don't know how much of an effect this would have; did the Uranus/Neptune visits "pay for themselves" momentum-wise? (Edit: I looked it up and apparently not, because Voyager 1 which skipped the last two planets is further out and travelling faster than Voyager 2). One thing we can do now which we couldn't do back then is build a good ion drive. A probe with an ion drive and a nuclear fuel cell could keep accelerating for many years, so it would probably be able to outpace Voyager eventually. So in conclusion, if we wanted to build something faster than Voyager I think we probably could. But in answer to your second question, no, I don't think it would be very useful to do so. There's not much that's particularly interesting beyond the solar system. We're still keeping Voyager alive because we might as well, but sending another probe out there with it would be a fairly low priority for missions.