In The Martian, I understand that all the bacteria would have died after getting exposed to Mars' atmosphere with sub zero temperature, but Mark's poop will always have bacteria to cultivate more crops. So why did he stop growing more crops?

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    Its not made clear in the movie, and its not made specifically clear in the book either - but I think its a combination of having no-live-potatoes (exposure to martial atmosphere for a day), no live soil, and he'd have to regenerate all the water again and doesn't have an infinite amount of fuel to use. I think we're meant to presume that one or other of these resources is no longer enough to regenerate the entire farm.
    – iandotkelly
    Oct 16, 2016 at 16:05
  • He is out of potatoes. He's used them all to grow the crops, when the HAB explodes, all the potatoes die.
    – Ben Plont
    Oct 17, 2016 at 0:38
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    Nope he was not out of potatoes in fact some scenes later he was counting potatoes what all were left. Oct 17, 2016 at 7:11
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    @saurabhsaxena you can eat and get nutrients from dead potatoes. You cannot grow new potatoes from dead ones.
    – cde
    Oct 17, 2016 at 16:42
  • I don't understand how he originally grew new potatoes from one's in the fridge, if he can't grow new new potatoes from the ones he had in the fridge Apr 29 at 5:23

2 Answers 2


Because he lacked the resources to start over. All the plants/potatoes were dead from lack of oxygen and sub freezing temperature. The bacteria in the poop soil as well. And his source of fuel that he could turn into water.

So he had nothing to plant, in soil that was sterilized, with no water to sustain it. The potatoes are no longer suitable to plant, just to eat.

Of the three, maybe he could start over with his own collected poop or some left over poop, and maybe he had fuel left, but without any living plants or seeds to start with, it's a no go. And even then, it's a question of yield. With very limited supplies, all the work he would put in to start over would not produce enough for him to survive on. His initial setup was already small, but with enough supplies to live on for months. After the accident he would have slim to none. A single potato and a single human poop factory is not sufficient.

As the books put it: Potatoes are now extinct on Mars.

Side note: The book explicitly states that the bacteria survived the accident, and was growing, so it's really down to not having anything to seed.

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    Thanks your answer is complete and logically correct. P.S. I went down to do a little research on if mars' environment can kill a potato and turns out it can. Nov 4, 2016 at 17:01
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    If he is a botanist and not an idiot. Shouldn't he have figured out that leaving potatoes to freeze all night will cause them to die? He could quickly fetch as many as possible and store in rover until the hab was patched up, even take some soil with him. Even at sub-zero temps, because of low air density, the heat transfer would have happened slowly anyway. He could easily save some plants to restart. He only needed few plants to restart.
    – yurtesen
    Dec 1, 2018 at 20:49
  • Where did he get the live potatoes in the first place then? Apr 29 at 5:21

You are making a good point. In terms of how the science was presented in the movie, there appears to be nothing stopping him from starting over. But here are some possible things to consider:

  • The great amount of effort for a full restart will only make another mishap all too possible to justify the effort.
  • Other crucial activities for survival put a full restart lower on his list things to do to not die.
  • Mark has a unique ego that drives him. Perhaps being the type of man that is "the best botanist on Mars", a "space pirate", and the man who "goes Ironman" mean he will not pursue what he perceives as a failed strategy.
  • The catch all: That's what will make the movie plot move along.
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    I don't see this honestly - he needs food to extend his time, with an uncertain time until he can get emergency supplies from Earth. I think the only thing that would stop him making more food is that he cannot because one or more of the components he needs is missing.
    – iandotkelly
    Oct 16, 2016 at 17:08
  • I agree. That is why I start off by saying a good point is being made. The following bullet points are there to only illustrate what the artists that made the movie might have been thinking to induce them to move on from that point.
    – John
    Oct 16, 2016 at 17:15
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    There was a similar question asked on the SF&F site. The accepted answer quotes parts of the book that give more detail to the situation.
    – bartuosz
    Oct 17, 2016 at 9:51

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