Student article – How accurate is the science of Ridley Scotts 2015 movie ‘The Martian’? Jacob Rees
Jacob Rees Aged 15yrs
Subject area: Primarily Biology, with a little Chemistry and Physics as well.
Key words: Ridley Scott, Mars, Martian, food
Considering this film came out in the cinemas on 30th September 2015 in the UK, I would have been only 12 then, and I have to say I thoroughly enjoyed it. This is not what we are here to discuss though, as this is not a review of a movie. This is tearing into the science of a movie to show that Hollywood didn’t do their research. During this investigation, I will be looking into the science behind Ridley Scott’s movie ‘The Martian’, and showing how this film is scientifically inaccurate (or this is, at least, my predication), which will include investigating the possibility of growing potatoes on Mars and surviving only off potatoes for the period in the movie.
Can you survive on a diet of Just potatoes?
Surviving 400 days on just potatoes, and a small box of rations you found left behind on your research base on Mars, sounds more than a little far fetched! Right? Well, that’s what I thought as well, until I started digging. Potatoes provide most things that our bodies need to survive, save for vitamins A, B-12, E, and calcium. There has even been a case where a man ate nothing but potatoes for about 2 months straight1
“Chris Voight, executive director of the Washington Potato Commission, set himself the task of cutting out all other foodstuffs for 60 days to prove the nutritional value of the starchy vegetable.”2
Obviously, this was not the most palatable diet a man could have, but it was enough to keep him going. The main problem lies in the portion size. Voight was eating around 20 spuds a day. At his best, we see that Matt Damon is eating only a single potato per day, as he is trying to ration himself. This is all good, until you encounter the problem that the human body requires around 2,000 calories per day to function properly, whereas a single potato only holds 159 calories1.
This, of course, is relative to the requirements on Earth. Mars’s gravity is only a third of the gravity on Earth, meaning that our Martian would have to spend much less energy to carry out work on Mars than he would have to on Earth. This means that, despite seeing him doing a ton of work every day to make sure he stays alive, he is spending much less energy in doing this. Add to his income some extra calories due to his rations, and some pills that we see his crew left behind (likely including vitamins), and it’s very easy to believe that the Martian could survive on this diet. So, well done Hollywood. Martian 1, me, 0.
Could you grow potatoes on Mars?
So, after realising that potatoes are a viable survival option for Matt on Mars, we need to now know how he is going to get these potatoes in the first place. Well, an experiment was conducted by researchers in the Netherlands to investigate this, by planting 4,200 plant seed in Martian-like soil for 50 days to see if they grew.
“I was very surprised when we found out plants grew better in the Mars soil than in the Earth soil. The Earth soil that we used was quite clean, a kind of river soil, relatively poor in minerals. But I didn’t expect the Mars soil to produce better plants, Wamelink told Euronews3”.
Unfortunately, there is a problem with this experiment. First, the control experiment they did used soil that was low in mineral value. So it was less likely to produce healthy plants than standard Earth soil, which gave the Martian soil an advantage. Also, we must consider that, on Earth, we have microbes that fix nitrogen from the air into nitrates in the soil, which are then a key ingredient in the plant’s growth, as they are used to make plant proteins. Mars is also 1.5x the distance Earth is from the sun, meaning it also will only get 60% of the sunlight, as shown in the image below.
Fig. 13 Mars distance 7
As a result, the potato plants are not very likely to grow, and if they do, it will be at a rate so slow that you should say your prayers4.
But low and behold, Matt has a solution to this, which is quite literally rubbish. As we see in the film, Matt Damon uses his own faeces as fertilizer for the potato plants, which in theory would work. However he makes one fatal mistake. All human faeces carries potential pathogens. We are immune to our own microbiome, but the microbes that come from other people could be pathogenic to us. This means that, when Matt went and collected the left behind faeces from his crew mates, and used this as fertilizer, he would have exposed the potato plants to this as well. This means they would also become potentially deadly to Matt. This is, again, if we were on Earth. The faeces (or biosolids) have been exposed to Mars’ atmosphere and temperature, which is at -60̊ C (-80̊ F) meaning that these biosolids would have been freeze dried becasue the temperature being so low, and therefore the pathogens would have died5. So, once again, Matt Damon gets away free of charges. 2-0 to The Martian.
My final point, which should surely be the winning point for me, is that Mars has something very deadly in its soil. Recent missions to Mars have all sent back conclusive evidence that perchlorates riddle the soil of Mars, which is a highly toxic chloride/oxide ion. They are salts, capable of disrupting the body’s metabolic systems. They are also able to interrupt our ability to absorb iodine, throwing off our hormones, which then disrupts sleep, appetite, and more. The thing is, these are salts, and they are soluble in water. This means that all the Martian soil needs is a bath, and the perchlorates would have been completely removed. You could even then get the water back, and dump the perchlorates by distilling the solution after removing it from the soil. This also then means a very small amount of water is needed to treat a large quantity of soil6. So, hate it as much as I do, that’s a 3-0 win to The Martian. I would congratulate Hollywood for this, but I won’t, as the original story came from Andy Weir in 2008. So, Andy, well done. You have won my seal of approval for your sound science.
- spacecoastdaily.com/2016/03/nasa-releases-some-fun-facts-about-mars-part-of-jouneytomars-program/ Date accessed: 14/7/18 (Only images were taken from this site)
Professor Anthony Campbell
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