Hitch a ride to the Kuiper Belt?
Can't we come-up with a way to get space probes quickly to the Kuiper Belt, the outer solarsystem or beyond?
We could engineer the "rendezvous" between space probe and comet, such that the probe becomes trapped in the gravitational field. The probe would orbit the comet as it it shoots out at speed to the other solar system. Once there, the probe may fire rockets, break it's orbit and zoom off to alpha senturi or somewhere similar.