Apollo 13: through Physics
How it works
The film “Apollo 13”, directed by Ron Howards, depicts events from the infamous failed Apollo 13 mission in a realistic fashion. Through the use of physics, many of these events can be proven to be accurate. More specifically, I will be investigating how Newtons three laws of motion facilitated the ship’s movements throughout its course, and how the implications of gravity affected the astronauts on their mission to the moon.
To see how these laws are applied to the film Apollo 13, we can first look at the initial launching of the ship from earth. As its launching, in the film the ship does not curve or stray far from its accent upwards, nor while breaching earth’s atmosphere. This is because of Newton’s first law of motion, being that “an object remains at rest, or in a uniform motion in a straight line, unless its compelled to change by an externally imposed force” (Brosing & Griffith, 2019, p.63). With that in mind, the shuttle in the beginning is at rest as it waits to launch and would remain there until a force was exerted upon it to cause it to move. The force in this instance would be the ships boosters acting on it to push it up and away from the launching pad and into space. This take off and power used to propel the ship is an externally imposed force placed on the resting ship. Another example of Newtons first law in the film can be seen during the separation in space of the ship and its boosters. The ship carrying the astronauts continues its straight path, while the 4 pieces of the craft behind can be seen traveling off into space in their own respective directions. These pieces from the ship fall under Newton’s first law in the sense that they will continue traveling along their current path and rate as long as an outside force doesn’t interrupt them, same thing being said for the vessel carrying the astronauts, since there is nothing to stop its motion in space, it would continue along the same constant velocity. Another example of the first law in the film is where the astronauts are taking off their gear once they’ve entered space. The gloves and helmets float around, and if the crew didn’t grab them, or if the ship wasn’t there, they would continue floating about until they hit something to change their path.
How it works
Looking to the initial take off of Apollo 13 once more, Newton’s second law is also at play in the force of the boosters against the pull of the earth. Newton’s second law is that “the acceleration of an object is directly proportional to the magnitude of the imposed force and inversely proportional to the mass of the object. The acceleration is in the same direction as that of the imposed force” (Brosing & Griffith, 2019, p.63). This leads into the ship, a smaller massed object, needing to experience a larger acceleration of force to break free of the earth, a much larger massed object. However, since the ship itself has an assumed high mass due to the size as seen in film, it will have, like all objects, a resistance to change in motion. For the Apollo 13 shuttle to take off successfuly, there needs to be enough force applied to the mass of the ship to propel it from its state of rest. This can also be applied to the re-entry of Apollo 13. As the ships gets closer to earth, the pull of the earth gravitational field speeds up the acceleration of the ship. As it re-enters the earths atmosphere, it slows down due to air molecules, however, the lost momentum converts to heat, which is why the Apollo 13 technicians were concerned about the re-entry, as they feared the heat resistant paneling could have been damaged (Deziel, 2017).
The biggest issue Apollo 13, and the reason it failed in its mission to land on the moon, was the explosion of one of its oxygen tanks leading to the failure of many of its systems and for the ship to move out of control. While a tragic turn of events for the crew and NASA, this too can be explained through physics. Newtons third law states that for every action there is an equal but opposite reaction, such as someone pushing a chair or lifting a pen (Brosing & Griffith, 2019, p.68). When you put force on a chair to move it, it also is exerting a force back, however, weaker then your own, which is why its able to be moved. The same applies to the explosion of the oxygen tank causing the out of control movements we see in the film on the ship. As the oxygen escapes the ship, the force of it being expelled causes the ship to move forward in the opposite direction to the oxygen. Newtons third law can also be applied to other aspects of the film, such as the ships take off from the launching pad and the astronauts’ ability to move about in the ship while in space. Since the rocket’s launchers are facing towards the ground, the force of them being set off causes the upward propulsion of the ship from its original resting point, making the ship take off and get altitude. Looking at the astronauts and how they move in space, they rely on the walls and different points of contact to propel themselves through the ship. So, that would mean that the force they are putting on the ship is lesser then that of the force the ship pushes back on them, explaining why the vessel doesn’t move but they do.
We are all subjected to the earth’s gravitational force keeping us on the planet, our satellites orbiting, and explaining the ‘weightless’ feeling experienced by astronauts in space, such as the crew in Apollo 13. To explain this, we can look to Newton’s law of Gravity. This law states that “gravity is a force that acts between any two objects with mass, and that force increases if the mass increases and decreases if the distance between the two objects increases” (ZuHone, 2007). This means that the further away from the earths mass an object is, the less force will be exerted onto said object. Looking at the film, as the craft is carrying the crew to the moon, this law comes into play. In one of the scenes we see a monitor with a projected pathway that the Apollo 13 craft is taking, going from the earth to the moon in a loop. Because of the speed it already has from its initial break from the earth’s atmosphere, it will continue to travel until it is brought into the moons gravitational pull. Then, as shown in the films drawn model, the Apollo 13 vessel will be slung back in the direction of earth due to the moons gravitational pull. This law is also demonstrated in the vessels re-entry back to earth, as the closer the crew got to earth, the force of the gravitational pull on the ship increased causing it to re-enter the atmosphere.
In the film, we see the decent of the ship as it comes back from space and see the parachutes deploy in order to slow down the falling ship for a safe landing for its crew. This process of slowing down and deacceleration too can be explained by looking at physics. As the ship is falling back to earth, the velocity at which they are falling would prove deadly, even though they would be slowing down due to air-resistance. The usefulness of the parachutes come into play here, dragging the ship and causing the total magnitude of the falling ship to decrease as well as any further acceleration (Brosing & Griffith, 2019, p.72).
Something to note during the duration of the film was their use of the scientific method in relation to the issues the crew and those back on earth used to assess their troubling situation. Take for instance the rupturing of the ship’s oxygen tank. During the initial chaos created, scientists on the ground were scrambling to determine the cause of the failures, throwing out the ideas of a possible instrumentational error to the vessel having been hit by a meteor (CITE NSTA). While these ideas were being thrown out, one of the crew members noticed the ship was expelling something- oxygen- into space. This observation alerted those on ground, who now had a better understanding of the situation taking place on the shuttle and allowed them to further aid the crew to ensure their wellbeing and survival. Through this method of critical thinking and evaluation, scientists were able to keep an open line with the Apollo crew and quickly assess any problems that arose effectively, from the tank’s explosion to the success of the handmade carbon dioxide filter.