When I was watching The Martian I really couldn't make a clue of this thing. And sadly all in the film that was stated about it (at least in the language version I watched) was, because they thought it would be a nice idea to drill a hole in his roof. But that's all and there was nothing else stated after that about it anymore.

Here is a picture of the thingy I'm talking about:

airbag on roof

So earlier problems that had not been mentioned how to be solved:

  • The temperature
    • He had at that time the radioactive module in the rover "spending heat" but I had the impression it could still get dangerously cold at night. So does this thing have any purpose of regulating temperature?
  • Generating oxygen
    • He has an oxygen generator but earlier it was mentioned that he will have trouble with the length of the journey as the oxygen won't last long enough, what let me assume no way to generate it on the rover. As after it no word was dropped how they solved this problem: Does this thing maybe some how support the regeneration of oxygen?

Or is it just solving a problem I didn't even notice coming up? I dare to doubt they didn't do it just because they thought it would be fancy.

If this isn't somehow on topic here, please be so kind to migrate it to movies SE.

But I assumed even it is based on a film this is probably better fitting here.


I don't remember if it was mentioned in the film but the main problem was that all the equipment he needed to bring for life support did not fit into the rover. So he needed more space and had to modify the rover (cut open the roof) to fit all the equipment. But he also needs the rover to be airtight (the equipment is the primary means of scrubbing CO2 and generating oxygen after all) so he had to plug the hole with HAB canvas material.

  • $\begingroup$ by more space needed are we talking about the required voloumina for oxygen? otherwise I don't get how this baloon should make space for any kind of equipment. $\endgroup$ – Zaibis Mar 7 '16 at 7:53
  • $\begingroup$ More space for the equipment. One of the equipment was taller than the roof so they needed to cut the roof. He didn't need the ENTIRE volume of the balloon, he just needed a few inches but that still means cutting the roof. The balloon was just the side effect of the fact that the hole was covered by a soft inflatable material. $\endgroup$ – slebetman Mar 7 '16 at 8:09
  • $\begingroup$ ah ok. so it is really bad presented by the film? they don't even mention or show a single time an equipment that is that tall. $\endgroup$ – Zaibis Mar 7 '16 at 8:12
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    $\begingroup$ A lot of things were altered or even completely cut out of the film to prevent it from being too long. The "space pirate" thing for example. The logic goes: he's about to commandeer a ship without permission from NASA. He couldn't get permission because NASA couldn't give him one. NASA couldn't give him permission because they have no communications -- SPACE PIRATE! However, in the movie they had communications all the way so NASA could give him permission thereby making him merely a space truck driver. $\endgroup$ – slebetman Mar 7 '16 at 8:17
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    $\begingroup$ Commenting on my own comment above I just discovered that technically the first case of piracy in space happened in 1973 in what is now referred to as the Skylab mutiny: en.wikipedia.org/wiki/Skylab_controversy $\endgroup$ – slebetman Dec 3 '19 at 6:40

The book explains the issue. The cab of the rover was too small for the duration of his trip. He wanted a 'spare room' that he could inflate while waiting for charging to complete.

There is a subplot not handled in the movie where he shorts out the Pathfinder rover by leaning the drill he was using against the cab, with an exposed wire. Then how he recovers from the loss of communication.

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    $\begingroup$ In the book, the spare room for extra space is separate to this rover mod - it's one of the emergency pop up tents that attaches to the rover airlock. $\endgroup$ – James Thorpe Mar 7 '16 at 9:16

In the book, he tows the second rover (IIRC, the second rover isn't in the film) behind the first. There's not enough space inside the second rover for the Hab life support equipment pieces (can't recall the technical names) that reclaimed oxygen from carbon dioxide, regulated oxygen levels, and reclaimed water that he had to bring with him. All of these needed to be inside the pressurized space. At least one of them was too tall to fit inside, so he had to make a "balloon" with "canvas" (not the flimsy Hefty garbage bags you see in the film, but flexible multilayered carbon-fiber composite). The two rovers share power and atmosphere through an umbilical, so he can breathe fine even through the life support is in the trailer.


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