Thanks for the ideas! Here is a summary of non-combat challenges I'm gleaning from all of this:
- Figuring out how to gain entry into the spaceship portion of the space hulk (reading augry, piloting a small craft, using cutting tools)
- Finding your way through twists and turns. To be accomplished by blocking the some primary corridors with debris. (navigation)
- Figuring out how to repower the ship, repressurize it, and getting command and control established (navigation, tech-use)
- Something they do triggers an depressization, potentially blowing the PCs or their hirelings into the void. (agility/strength)
- A room they need to pass through or enter is filled with heat and radiation. Can they brave it, go around it, remove the source of the radiation? (role playing, toughness, tech-use)
- A critical room (engineering, the bridge, a key control room) has a grav-plate malfunction. Anyone entering it gets thrown around until the malfunction is brought under control. (agility, tech-use)
- Some still active radioactive material is slowly burning its way through the hull. It must be brought under control, possibly risking the health of whoever deals with it. (toughness, tech-use)
- A member of the original ship's crew is preserved in stasis. If awakened they can get very useful information from him, but over the eons he has been corrupted by the warp, and he secretly wants to turn some of the PCs or their hirelings toward the dark gods. (roleplaying)
@Darkwinds: I'm sure how the fire would start? Also I imagine the PCs will bring a full compliment of void suits, and they'll need them because otherwise entering the hulk would be very difficult.
Thanks everyone, please chime in with any more ideas!