James Ball, OAPT Membership Chair, Physics Teacher, John F. Ross C.V.I.
James.Ball@ugdsb.on.ca

Rating: 4.5 out of 5 luminous gaseous bodies

The Martian is a very entertaining movie, which will appeal to a wide audience. As a physics/science/science teacher I found it to be particularly enjoyable.

I’m going to review it according to the science, technology, engineering and math that it presents (yup that’s STEM).

Science
The science comes into play once Watney (played by Matt Damon) realizes that he is marooned on Mars. His fellow astronauts think that he was killed by flying debris during a sand storm. Because of the storm they were unable to find his body and they had to abort the mission.

Watney discovers that he has enough rations to survive roughly an earth-year (1 sol) and knows that the next mission to Mars is several years away. Being a botanist (he is also an engineer) he determines that he needs to grow his own food. He has potatoes but needs organic matter to add to the Martian soil. His source of organic manner is human waste from the lab’s toilet. He also needs water. Using his knowledge of chemistry, he determines that he can produce water by burning rocket fuel in the presence of oxygen. In one of the amusing moments he almost blows himself up starting the chemical reaction. He uses a bit more care (and safety equipment) on his next attempt and succeeds. Using his ingenuity he manages to grow potatoes.

Technology
In order to get to where the next mission will land Watney needs to modify his rover. It has a maximum range of 35 km and he needs to travel about 3500 km. His rover uses batteries as its source of power. These batteries are also needed to heat the rover’s cabin as Mars cools down to –73° C at night. He realizes that a nuclear power source that was used as part of the rocket that got him to Mars is a good source of heat, just as long as he doesn’t perforate the shielding.

In order to communicate with Earth he needs to find an antenna. The lab’s original satellite dish was irreparably damaged by the sand storm. (The satellite dish is what collided with him and almost killed him.) He realizes that one of the original Mars rovers (Pathfinder) is within driving distance of the lab (after he extended the rover’s range). It was believed to have stopped communicating with Earth due to problems with its solar panels. He finds it, brings it back to the lab and manages to power it up.

Math
Meanwhile, back on earth, NASA has determined that he is alive based on satellite imagery showing that the rover changes locations. They also realize that he has gone to find Pathfinder and so they re-establish communication with it. This leads to one of my favourite moments in the movie. NASA can see him but how can they communicate with him? The camera is able to rotate 360°. Watney realizes that having 26 letters located on signs in a circle around the camera would mean that the angular difference would only be about 15° and thus it would be hard to distinguish the letters based on the camera’s movement. Instead he realizes that the hexadecimal system will give him access to the same information and an angular difference of 30°. Unfortunately the movie makes it seem like this communication was instantaneous while the radio signal from Mars to Earth will take anywhere from 4 to 24 minutes which means anywhere from 8 to 48 minutes in response time.

Engineering
Engineering is everywhere in the movie. Physics Professor Brian Cox twitted that “The Martian is the best advert for a career in engineering I’ve ever see.” (@ProfBrianCox) Another one of my favourite scenes is when the NASA engineers are determining what has to be removed to lighten the rocket so that Watney can use it to escape from Mars. The rocket is too heavy to reach a sufficient altitude to rendezvous with the rescue vehicle. They know the rocket has to lose 5000 kg. The nose cone is 500 kg and it gets removed and replaced by a tarp. This is possible because there is not much atmosphere and so little need for the cone to reduce drag.

Is it all good?
NASA has indicated that the Martian sandstorms, though frequent and problematic, only produce maximum winds of 100 km/h. This would not have been strong enough to cause Watney’s accident nor would it be sufficient to cause a mission abort. However the movie (based on the book The Martian by Andy Weir) gets a lot more right than it gets wrong. There is a great deal of drama and some intense moments. The physics is awesome. The movie is great fun and really sells STEM. I am currently trying to arrange a field trip with my physics students to see the film. The science shown in this film fits into the Ontario curriculum in the following courses;

• Grade 9 science (ecology and space units)
  

• Grade 10 science (chemistry)
  

• Grade 11 and 12 physics
  

• Grade 12 earth and space science

Tags: STEM