Near the end of The Martian movie we see Mark Watney shirtless, and his body appears to be bruised. What is the cause of these marks? I thought it might be from scurvy or some other malnutrition.

  • 3
    Well, he did go through two explosions and one rapid decompression...
    – FuzzyBoots
    Oct 6, 2015 at 23:13
  • 2
    Malnutrition and lack of bathing?
    – Joe L.
    Oct 6, 2015 at 23:19
  • 1
    @SeanDuggan The marks OP is referring to happened after the "7 Months Later" tag. He'd certainly have healed by then.
    – Nerrolken
    Oct 9, 2015 at 17:10
  • @Nerrolken: Gotcha.
    – FuzzyBoots
    Oct 9, 2015 at 17:24
  • Scurvy. He's a space pirate, after all.
    – Crashworks
    Mar 4, 2016 at 7:29

6 Answers 6


When Mark takes the suit off in the ship at the very end of the movie everybody complains about his body odour.

He says " I haven't had a shower in a year".

Having been in a similar situation ( with no acces to water for a long period of time ) I can tell you that his marks look a lot like something you get from not enough personal hygiene combined with a poor diet.

this this

  • Interestingly, as far as I remember, there is no mention to these lesions in the book... Oct 22, 2015 at 1:59
  • It's very possible it is from malnutrition and hygiene. In the book it mentions there are enough vitamins to last for a long time but this is not mentioned in the movie so I would suspect that route
    – Huangism
    Feb 26, 2016 at 21:58
  • I just rewatched this move last night by downloading it off the Internet and that scene seems to have been edited out. I'm glad I got the sanity check to know I did not misremember.
    – Steve
    Nov 26, 2020 at 12:19

I was struck by the skin lesions/rash as well, and have been looking for an explanation. I suspect it had to do with prolonged exposure to radiation. The Mars atmosphere is very thin, 100 times less dense than Earth's. An astronaut wouldn't have the same protection from solar radiation that we enjoy on Earth.

  • 1
    The protection from solar radiation would come from the magnetosphere, rather than the atmosphere. Mars has a weak, bordering on non-existent magnetosphere. There are parts of Mars which have magnetism but not enough to shield the planet nor any space travellers.
    – heptapod
    Oct 7, 2015 at 17:24
  • 3
    This cannot be correct. If those were the marks of radiation sickness, he would be dead within weeks, if not days. Oct 10, 2015 at 22:48
  • Also the book handwaves radiation issues away with an argument about the HAB's canvas doing the shielding (WTF!). Not that he also stays outdoors quite a lot.
    – Ghanima
    Nov 27, 2015 at 7:00
  • @MichaelBorgwardt I think he also travelled with radiating plutonium?.. Nov 27, 2015 at 9:36
  • 2
    @prakharlondhe: basically the radiation is caught by the shell and converted to heat (it's alpha radiation, which is very easily shielded). In the book, it is mentioned that if the shell gets damaged, it could kill him. But my main point is that radiation sickness bad enough to leave the kind of symptoms visible in the movie is not something you recover from. Since he does recover, it could not have been radiation sickness. Nov 27, 2015 at 9:43

He appears to have pellagra, which is due to deficiency of niacin (Vitamin B3) or the amino acid tryptophan, neither of which are present in sufficient quantity in potatoes to prevent this micronutrient deficiency.

  • 1
    Do you have any references to back this?
    – Joe L.
    Oct 10, 2015 at 21:49
  • 3
    In the book Mark notes that he has an overabundance of vitamins, he's only worried about calories.
    – Chahk
    Oct 13, 2015 at 20:36

Could be 'bed sores' from living in a pressure suit for as long as he was forced too. Staying outside the transport so it could charge up might make for all kinds of marks on his skin.


The lesions/rashes were shown at the same time his much thinner body was shown after 7 months or so.

This could have been due to prolonged diet of boiled potatoes without any source of Vitamin C and other vital ingredients.

  • 2
    The book specifically states he had enough vitamins for a long time. Oct 8, 2015 at 16:57
  • 3
    @DeerHunter The movie generally follows the book pretty closely, but may not have on that particular point.
    – Wossname
    Oct 8, 2015 at 21:19
  • 1
    Potatoes have plenty of vitamin C. One serving contains 70% of the daily value, according to google.
    – Nerrolken
    Oct 9, 2015 at 17:11
  • @Nerrolken: Incidentally, probably under Weir having done his homework, potatoes are about as close as we get to a "superfood". They're missing a few complex proteins, but you can survive a long time on just potatoes and water.
    – FuzzyBoots
    Oct 9, 2015 at 18:51

He broke a couple ribs due to the 12G's he experienced during the MAV ascent. Being yanked along by a tether with Beck didn't help matters.

  • 12
    The scene in which Watney appears shirtless with a skin rash and skin sores is before he makes the MAV ascent.
    – Praxis
    Oct 7, 2015 at 0:21
  • He was also injured by being thrown in the airlock. Oct 7, 2015 at 0:52
  • 1
    @JacobKrall - that was looong before the ascent. Oct 7, 2015 at 10:02
  • 2
    @DeerHunter: the scene in question was also looong before the MAV-4 ascent, given that Mark has just finished taking a shower in the HAB - he hasn't even started the rover journey to Schiaparelli Crater yet! Oct 8, 2015 at 16:35
  • @JacobKrall - ah. Okay, I stand corrected. Oct 8, 2015 at 16:55

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