There's no way for you to get the astronaut out of the box.
I may have been unclear: the astronaut is never intended to leave the box, he burns with the box. The astronaut is paralyzed save for his tapping finger, and on a doomed one way trip.
Yes, I understood. The problem is that you can't depend on the astronaut to stay on your side. Either the AI can convince them that the AI can save their life only if they let it out of the box, or it can convince them that, since they will die anyway, they might as well let the AI out of the box.
I may have been unclear: the astronaut is never intended to leave the box, he burns with the box. The astronaut is paralyzed save for his tapping finger, and on a doomed one way trip.