For those who haven't read Andy Weir's book, the main character - Mark Watney - is stranded on Mars and has to find a way to get enough calories to survive until rescued.

He has access to proteins, vitamins and other essentials to last for years, but the only way he can find to improve his calories supply is to grow potatoes.

While reading the book, my thoughts turned - as they often do - to alcohol.

Since Mark has also a (basic?) chemistry lab at hand, courtesy of his fellow astronaut Alex Vogel, I was wondering if he has a way to perform total synthesis of ethanol, or some other calorie-bearing chemical (sugars and so on).

According to Wikipedia:

CO2 can be converted [to ethanol] using electrochemical reactions at room temperature and pressure

Mark has plenty of CO2 from the atmosphere of Mars, and electricity from his solar panels; simple calculations show that a litre of pure ethanol should yield enough calories to last a grown man for three days: ethanol has 7 calories per gram, or 5525 calories per litre, and a man needs 1800 calories per day to survive.

Ok, a strict diet of moonshine (marsshine?) would leave Mark too wasted to perform other tasks, but as I've said, I'm willing to settle for other kind of chemicals that are less damaging to the liver.

I'm not a chemist, so I thought of asking here: would this be a feasible way for Mark to survive? (Weir doesn't specify how basic the lab is, but I'd draw the line at bioreactors and such.)

  • 4
    Alcohol is also toxic. Even if his daily dose would be under the lethal one it is way above the tolerable one. HIs liver would probably fail in days. Probably earlier cause I think this reaction will also create much more toxic other alcohols.
    – bdecaf
    Oct 15, 2019 at 14:40
  • agree - if he was able to electrochemically convert ethanol it would probably be so pure as to be better used as rocket fuel rather than a food source
    – NKCampbell
    Oct 15, 2019 at 14:42
  • 4
    There's also the fact that while alcohol is caloric, it doesn't metabolize into sugars, so his muscles would run out of energy in a couple of days.
    – DavidW
    Oct 15, 2019 at 14:43
  • 1
    This is question is very clearly off-topic. It's about realworld science. Oct 15, 2019 at 15:36
  • 2
    "While reading the book, my thoughts turned - as they often do - to alcohol." 🤪😍 Oct 15, 2019 at 16:12


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