@asian1
I no nothing about this, but I believe that radiation-hardened components are always quite a way behind "ordinary" components, and you don't want to be at the bleeding edge of hardware for mission-critical applications.
Are you sure that they use 8086's on the ISS - if so, I presume that they're still made, since its a fairly new space station ;-) (Z80s are still made - there's still a demand for simple microprocessors) As for why they're using designs
that old - why do they need anything newer? An 8086 will probably crunch numbers quite fast enough for what it's needed for, won't have any cooling or power problems, and they've probably got lots of experience with them. I guess that they're also cheap enough to have loads as spares :-D Finally, don't forger that these older chips are fabricated with much larger components. This is definitely an advantage - less heat produced, and if a stray particle whacks into the chip its less likely to cause much damage.
---edit---
Hmmm - done a quick search and it seems that the shuttle used to use 8086's, untill they had to start looking on EBay for them :-o That said, I don't agree with this:
Until recently, the flight-deck computers on the space shuttle used old 8086 chips from the early 1980s, the sort of pre-Pentium electronics no self-respecting teenager would dream of using for a video game.
Does this guy seem to think that the shuttle needs game-style visualisations, or that simple trajectory calculations need more processing power than an immersive 3D game? It's not rocket science :-P