Subject: Re: Voyager 1
Voyage 1 is 46 years and counting. I think the original mission plan was for about 5 years. It completed its planetary missions in just over 3. Voyager 2 was similar, and they were able to add Neptune (not part of the original plan, as I recall).

NASA is really good at making things that far exceed their planned lives. Look at the Mars rovers, for example.