Why do the pods have explosive bolts in 2001: A Space Odyssey?

Question

A random thought just occurred to me: in 2001: A Space Odyssey, the pods have prominent "caution: explosive bolts" signs on the back, and

Dave Bowman uses these to re-enter Discovery without his helmet.

My question is, what is the in-universe purpose of this system? The hatches on the Apollo Mercury capsules had explosive bolts, I guess in order to ensure they could be opened after re-entry and splashdown. But the pods in 2001 are clearly not designed for re-entry, so the explosive bolts on their hatches must serve a different purpose.

Is anything known about the bolts' intended purpose? (It's not mentioned in the script but perhaps was mentioned in interviews/the book/script drafts etc.)

Answer 1

Your guess about explosive bolts on the Apollo module hatch is wrong; they were added after the Apollo 1 fire and their purpose is to allow the crew make a fast and easy escape in the event of an emergency. (Source)

There doesn't seem any reason to assume any different purpose for the Discovery pods. In fact the movie and book were both being made at around the same time as the fire, so the addition of explosive bolts, and the reason why, would have been topical, although I'm not aware of any direct citation from either Clarke or Kubrick to confirm.

Answer 2

While it's not clear of the purpose of the explosive bolts. They did come in handy when Hal locked Bowman in the pod and he needed to escape. I would guess they were for emergencies, if (for instance as Bowman did) there was an issue with opening the hatch on the pod and it had to be forced open.

Dullea in the DVD commentary highlights the usage of the explosive bolts

“After HAL denies him entry, Bowman has to force himself into the ship through the emergency hatch by pressing the pod against the hatch—the are explosive bolts that will explode him into the ship—we see him being sucked into the ship. For a moment he’s in a vacuum. It was researched, and a scientist told Stanley that a human being could last x amount of seconds in an air lock and survive it, as long as it isn’t more than x (he thinks 15?) seconds.”

Here's a YouTube clip showing the scene.

From the above it seems like a reasonable assumption that the astronauts were provided the possibility of manually exploding open the bolts as a last resort escape out of the hatch of the escape pod.