Re: "It's a very strong design,"
> a testament to the dedication humans are capable of
Indeed, we are (and have been) capable of great engineering for a long time. Planned obsolescence has creeped so deeply into our consumer appliances, and our psyche, these sorts of feats seem even more impressive now. In reality, humanity's overall engineering skill has advanced so far, the greatest can now design a tool with a 2 year warranty to die after 2 years 1 month. (The guy who designed a tool that lasts 8 years got fired, he nearly collapsed the company by impacting future tool sales).
We've known how to design things to last as long as possible for a long time now, in fact we've only gotten better at it. It's just VERY rare that is ever the goal, even commercial equipment vendors need to make a living off of service contracts. One of the few scenarios where it's actually *economical* to overbuild the hell out of it, is spacecraft design (you've only got one shot).
2nd thing: I'm marveling at this right now, can't believe I've haven't realized it yet: whatever you call that duplicate "ground spacecraft". I've known about them for some time, even seen used in movies like Apollo 13 and The Martian, but their importance always seems downplayed. It made me think till now this was a "nice to have" thing, but in fact I've just realized, this is 100% a necessity for every space mission! How the hell do they keep extending missions decades beyond planned lifespan? How the hell do they test these "dirty hacks" that keep them operational for so long? That 'ground spacecraft', I've realized, is absolutely essential to keep any mission running!