Corrected entry: To increase the chance of success, there's a backup for everything: we have 2 crews, with 2 shuttles, 2 armadillos etc. However, when we get the crisis where the government wants to blow up the nuke before the hole is finished, there is only one bomb. Isn't there a second nuclear bomb in the shuttle that crashed?
Correction: They lost communications with that ship and (presumably) everything on it. That's why they say nothing about detonating the second bomb.
Corrected entry: Considering their space suits are made to measure, where did the Russian get his special anti-zero gravity suit from?
Correction: I assume NASA had them carry extra spacesuits just in case.
Correction: The suits they use on the asteroid could be universal as we can see two unused suits in the scene when Harry and AJ takes the elevator down for the last time.
Correction: When the shuttle is careening out of control, a bunch of equipment is flying out of it. It's possible the nuclear bomb was sucked out as well.