The Martian movie obviously had a lot of thought put into it, to make it (more) realistic. But one thing vexes me. Why did Dr. Chris Beck travel around the outside of the Hermes in order to get from the position where he was originally set to meet up with Mark Watney, to the place where the bomb was delivered to him?

It seemed like both places were in micro-G, so I picture the path through the interior of the ship would have been all in a micro-G environment. On the other hand the path around the outside, where he commonly needed to let go of hand holds and drift through free space, seemed rather dangerous. He had no propulsion with which to correct a wrong move, so just one wrong trajectory and he'd have drifted past his aim point and (potentially) off into space.

  • 1
    – Valorum
    Commented Oct 15, 2016 at 14:17
  • Well, the article basically says "They wouldn't have". I'm not sure it's actually an answer.
    – Valorum
    Commented Oct 15, 2016 at 14:39
  • @AndrewThompson - is this EVA present in the book (I read it but don't remember)? If not, you may add it to the list of things (like the Iron Man glove stunt) added by Ridley Scott to make the movie more exciting. Most probably, there is no in-universe explanation. Commented Oct 15, 2016 at 16:45
  • @Gallifreian I haven't read the book. Commented Oct 15, 2016 at 16:46

1 Answer 1


The film (and the screenplay) don't elaborate on this, but the book does: Beck had to crawl on the hull because when they blew the tip of Hermes, they blew one of the doors, and you need two doors to be able to enter the ship1.

“We’re going to have to literally blow up one of the doors,” Lewis explained. “I’d rather we kill the inner one. I want the outer door unharmed, so we keep our smooth aerobraking shape.”

“Makes sense,” Beck responded as he floated back into the ship.

“One problem,” Lewis said. “I want the outer door locked in the fully open position with the mechanical stopper in place to keep it from being trashed by the decompress.”

“You have to have someone in the airlock to do that,” Beck said. “And you can’t open the inner door if the outer door is locked open.”

“Right,” Lewis said. “So I need you to come back inside, depressurize the VAL, and lock the outer door open. Then you’ll need to crawl along the hull to get back to Airlock 2.”

“Copy, Commander,” Beck said. “There are latch points all over the hull. I’ll move my tether along, mountain climber style.”
Chapter 26, emphasis mine.

1 Strictly speaking - he could enter the ship, but the lengthy process of repressurising it (they evacuated all the air, after all) would not allow him to make it in time.

As pointed out by @davidbak, Hermes in the film is different from Hermes in the novel.


According to Andy Weir's description in a Reddit AMA, Hermes was different in his view:

I imagined an Hermes as being a very large cone-shaped ship, like a super-sized Orion capsule. It was split down the middle and the two halves could separate, attached with cables, and spin to provide artificial gravity.

It would look like a blend of the two pictures below:

The left option. The heat shield was not split. It remained a solid circle in the center.

E.g. the upper half is a solid cone, and the lower half is two halves of a cone with its top cut off.

  • 1
    And in that last sentence we see the major difference between the book and the movie - the latch points disappeared. Probably done in the interest of excitement, or possibly, pacing. But that's the answer to the OP's question.
    – davidbak
    Commented Nov 30, 2016 at 3:43
  • @davidbak - the latch points disappeared because Weir's Hermes is not the same as Scott's. I read somewhere that Weir had a conical ship with a hollow intersection in the middle; alas, I wasn't able to find the source. Commented Dec 30, 2016 at 17:37
  • 1
    Note that this only concerns Beck crawling back, after he planted the explosive and locked the outer VAL door in open position. There is no reason for him to crawl to the vehicular airlock, and indeed, he takes the interior route in the book.
    – Santa
    Commented Jan 1, 2017 at 16:15
  • 1
    @davidbak - found Weir's description here Commented Jan 9, 2017 at 13:03

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.