u/Kotaruchan

As the title asks, if you were to build a generation ship and solved the many issues with long space travel concerning the human body et al., how do you keep the ship itself functioning over a very long time? For example, 20-year-old cars are already rare as they start deteriorating after heavy use/time, home appliances as well, work machines, you name it, if a machine is a few decades old chances are it's either decommissioned or in maintenance hell. Heck, ISS has gotten pretty crappy and that was only launched 27 years ago and about to be decommissioned.

So, how do we build a spaceship that's still livable for unmodified humans, at least until it leaves the solar system's influence, and, hopefully for the humans aboard, even after the journey through the stars? Because we can't exactly have pit stops on the way, unless we somehow keep island hopping through the Kuiper Belt/Oort cloud..

Quite a lot of posts point out that, about the only candidate for a close supernova out there, Betelgeuze, being ~450 ly away from us would pose no risk to us, other than being about as bright as the moon.

But what about over larger timescales? About 4,5 million years ago, two massive stars in the Canis Major constellation, Epsilon CMa and Beta CMa, came within ~30 ly of the solar system. 4,5 my when you really think about it isn't that long in the history of Earth, so do we have any estimate what the risk of a supernova at 'unsafe' distance happening is over longer time?

Edit; corrected distance