So, at the end of H3, Cortana tells Chief that it's gonna be a long time before they're detected.
Chief tells her to wake him up if anyone finds them.
But, I remember reading in Fall Of Reach (or maybe First Strike, can't quite remember) that Cortana has a limited lifespan.
If she "died" before anyone came, Chief would be frozen for pretty much all time, wouldn't he?
Can anyone confirm her lifespan? I'm not sure, but it seems like a bit of a problem for Chief.