The Martian: The Science in the Sci-Fi

The Martian is a science fiction movie released in the second half of 2015, based on a novel by Andy Weir. It is the story of how an astronaut, Mark Watney, was accidentally left behind on the surface of Mars after a storm, with his colleagues thinking he was dead. It was directed by Ridley Scott, and the screenplay was by Drew Goddard. The film won many awards, including the Golden Globes, The Hugo and the People’s Choice Awards, and was nominated for the BAFTA. Clearly, the movie was loved by many. Here we will take a quick glance at what it did right, and more importantly, what it did not.

The Plot

Before we jump into the science behind the story, we must first have at least a rough idea of the story itself, to bring those who have not watched it up to speed and jog the memories of those who have. Without going into much detail and giving out too many spoilers, here is a small plot summary that is taken from IMDb:

During their mission on Mars, a team of astronauts is hit by an unpredicted storm and have to abort their mission and leave for Earth. During the evacuation, one of the crew members, Mark Watney, is hit by a projectile due to the storm and is thrown away. The crew is forced to leave him thinking he died due to rupture in his spacesuit. However, Mark survives and now has to find ingenious ways to make it till the next scheduled Mars mission fours years later with the remaining meagre supplies. Being a botanist he manages to cultivate food and survives by scavenging parts of previous missions. NASA soon learns about him and attempts a daring and dangerous mission to bring him back. Will they succeed in bringing him back alive? Only time will tell.

—Keith Francis

For those who crave more details and wanna know how the story ends, we recommend watching the movie 😉

What it got right…

Making water

Although recent discoveries show that there is water on Mars in the form of permafrost and that Martian soil contains 5% water at low latitudes and up to 60% at the poles, Watney decides to synthesize water with the help of rocket fuel hydrazine. 

Hydrazine is basically H₂N-NH₂, which is two amine groups bonded to each other. The following reaction takes place at 983K:

N₂H₄ -> 0.91NH₃ + 0.54N₂ + 0.64H₂

This is a net reaction, in fact, there are a couple of reactions taking place together. And of course, he burns the hydrogen to get water. 

But of course, it is also true that burning hydrogen is dangerous…

Growing Potatoes

Of course, the first problem that we see with this factor is that Martian soil is not the same as the soil on Earth. For one, it’s very fine. And secondly, the composition of Martian soil is much different than that of the Earth. 

The mineral matter is low on essential nutrients for plants and also has significant amounts of perchlorates, which are toxic to humans. Plants would either become toxic themselves or grow slower. Do we see Watney look like he was suffering from the effects of starvation or toxicity, we don’t know…

Another thing, the lack of nutrients can be overcome with the use of additional manure or fertilizer, and human waste can work. But, human waste, when untreated, also contains pathogens that can make you sick. But, an argument can be made that you can’t be sick from the pathogens you already have, hence Watney looks for his own waste. We also see him heat treating his potatoes (cooking them, that is) and this is a good way to reduce the risk of falling ill. 

Survival of the Launch

Towards the end of the movie, Watney has to escape Mars’ orbit in order to be reunited with the Hermes crew. His rocket is stripped down, and barely counts as working, and he actually manages to pull it off. Here’s the question, is it possible?

According to Dr. Robert Zubrin, the math checks out! The thin atmosphere of Mars provides an advantage here, as it is so thin, that it requires a high enough acceleration to start burning up. 

What they got wrong

The Hermes Ship

Although the production of artificial gravity is a good touch that is accurate, the problem with the ship has to do with another factor: radiation. 

On Earth, we are protected from solar radiation by the atmosphere. But once we leave the planet and its protection, the ships need to be shielded. But from the picture, we see that there are glass windows. With our current technology, we cannot make such shielding work, and hence, this one is categorized as more fiction than science.

The Storm

Let us address the elephant in the room: the storm.

Remember how we were harping on about how the Martian atmosphere is rather thin? One of the implications of this fact is that storms in Mars are much weaker than in Earth. So what we see as a huge hurricane-like dust storm would feel like a breeze. Even if we grant it the strength to break off the antenna, it is highly unlikely to cause the damage it did to Watney.

Now that we think about it, the movie wouldn’t be much of a movie if this didn’t happen, right? 

The toilets…

Okay, hear us out. Why would NASA design toilets that basically stored and individually labelled each astronaut’s waste for future study? I mean, wouldn’t it make more sense to bag it and then dispose of it, like they do in the Arctic exploration missions? Or, why not recycle it into fuel, water and oxygen? 

Why would you study it on Earth? Why would you study it on Mars? They are there to study Mars, not poop. 

Communications

After the main communications antenna is broken, Watney has to find another way to send messages back to the team or NASA. He decides to find the Mars Pathfinder probe and repair it, and then contact NASA via the hexadecimal system. 

The problem with this is that rovers can directly communicate with Earth, without the use of additional equipment. While it adds a lot of tension and plot to the story, it’s not very scientifically accurate. 

The Climax

Despite these errors in the movie, it is a good starting point for anyone who wants to start exploring the fields of astronomy and space. Not to mention, the things that it got right are done so well that perhaps we may overlook the inaccuracies. Not to mention, these errors (except perhaps the last one on the list) are only a factor with our current technology and knowledge. Maybe as time moves on and science and technology advances, they may not remain to be factually incorrect. 

Even for a person who isn’t a science nerd or someone from the STEM field, there is a lot to enjoy. The plot is strong, the VFX, when used, is well done and the story is compelling. Overall, definitely a movie that is a joy to watch, about a planet that has captivated our imagination for a long time.