Why is Captain Janek wearing a spacesuit outside?

In the latest featurette, you can see a scene being filmed where Janek, the last person who should be leaving the ship, is out exploring in the dark with Shaw, I think, maybe in the temple. Also, what is just as weird is that David would bring back one of the ampules into the ship, and open it up, yeah just super reckless. Add to that the helmetless walking around in the temple and you gotta ask yourself, are they all nuts or is this going to end up being some sort of crazy hypersleep dream that Shaw has.