Medications and clothing could be degraded. Adhesives. Food, water and oxygen have to be supplied without fail, and no system or systems is/are foolproof.

It's not as if when all else goes one can head for a cave and live off deer or zebra, wear furs and drink from the closest stream.

I believe Mankind would be better off building a few "domes", or habitats, here on Earth for the eventuality of a catastrophic asteroid or comet hitting. Ride out the effects for 10, 20, 50 or 100 years with a ready supply of whatever is needed reasonably close.

Maybe a few nuclear subs able to sit on the bottom for a few years. They could come up every once in a while and monitor conditions. When the time was right, they could surface into pens with domes which have been prepared. (Allow NO politicians. Won't need 'em.)

Instead of decommissioning the things, remove the offensive and defensive equipment and make them a bit more liveable.

But I think our best, and until technologies as yet just figments of very active imaginations come onto line, or only chance is to do it on good ol' Mother Earth.

Arf