With the imminent death of Cassini after 15 years, and the Opportunity Rover 14 years old and showing its age, and Voyager 1 at 40 years, and space being "...big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is..." I got to thinking about projects that might span multiple scientists' lifetimes.
Practically speaking, after all the schooling and then working your way up the corporate (or government) ladder, you might be as young as 30 when you get onto a Big Space Project.
From there you could have 30 years of practical, hands-on, operational role in a project (like Cassini), of which 4-10 will be getting budget, testing, building, and launching the craft.
So that leaves you with 20 years of practical hands-on experience with a flying, active project. Which is not a lot of time, when you think about how big our solar system really is.
So are there projects on the boards now that are planned to span more than one human generation of engineers?
Clearly Voyager has seen almost a complete staff turnover. But are there projects that are planned to be productive beyond the lifetime of a single generation of scientists?
I figure francopoli and kleinbl00 and Dala might have some input, and I welcome comments from anyone else. Let's not get too sci-fi, but Musk's plans for Mars obviously fall into this category, too...
Alan Stern, the lead on New Horizons has spent an entire career making this mission happen. His first proposal for a Kuiper Belt/Pluto Probe was in the mid-80's. This is a whole career pushing for a singular mission.
The Jupiter moon missions are being pushed by people who were engineers for the Voyagers.
Something tells me that you do not mean a whole lifetime to get something launched, but there are a few examples.