If you have ever asked someone a question that they felt you should have known the answer to, they might have said, “It’s not like it’s rocket science!” By saying this, they might mean that rocket science is a very tough and complex subject. But is it really?
Rocket science is the science of designing or building rockets with the purpose of being launched either to a different part of the Earth or to space. Every single object that has a mass (mass measures how much matter an object has) is attracting, and is being attracted by, another object. This force is called gravity. This concept applies to the tiniest atom and to the largest galaxy.
Everything in the universe that has a mass is attracting something else and being attracted by something else. So then why are we not being pulled by everything in the universe? The answer has to do with mass and distance. The gravitational force between two objects equals the mass of the first object multiplied by the mass of the second object multiplied by the gravitational constant all divided by the distance between the two objects squared (F = (G x m1 x m2) / d^2).
Because Earth’s gravitational force on you is stronger than your gravitational force on Earth (because the Earth is more massive than you), Earth is able to pull you towards the ground (which is your weight). The higher up you are in altitude, the smaller your weight. The amount that your weight decreases on Earth (if you compare your weight at sea level versus your weight at the top of Mount Everest) is miniscule and unnoticeable. Additionally, when you are in space, you are not attracted to the other planets because you are too far from the other planets. You still have a small attraction to the planets but it is not enough to be noticed by you.
The equation F = (G x m1 x m2) / d^2 was written by Issac Newton. Newton came up with three laws of motion. The first law of motion is inertia. This law states that an object at rest will stay at rest unless a force acts upon it. Similarly, an object that is moving will keep moving unless a force acts upon it. The second law of motion states that force is equal to mass times acceleration (F = m * a). This means that the more massive an object is, the more force is needed to move that object.
The third law of motion states that every action has an equal and opposite reaction (those are also the lyrics to “Washington on Your Side” from Hamilton). If you throw a ball towards a wall, the wall will bounce back. If a swimmer is swimming forward, they will use their hands to push the water behind them. If a rocket is being launched, it will push against the ground to be pulled up.
Space starts roughly 60 miles, or 100 kilometers, above Earth. At that point, Earth’s atmosphere is still present, but it is the blurred place in which space is thought to begin. Space has a ton of things such as planets, comets, galaxies, and dust and so it is a big place. In fact, the whole universe is so big that it is forever expanding. This means that the volume of space can never be measured because it is technically heading to infinity.
Since space is the place above / around the top part of the Earth’s atmosphere, a space rocket has to have a huge amount of speed and energy to escape Earth’s atmosphere. Thrust is the force that pushes a space rocket upwards. The thrust of the rocket must be greater than Earth’s gravitational force to actually move up. But gravity is not the only thing thrust has to push against. There is a drag force, air resistance in this case, that also pushes in the opposite direction of thrust. The rocket ship is designed to have a “nose” and be thin because this helps cut through drag. If drag is acting on less of the rocket, it will be easier for the rocket to move upwards.
A rocket has to reach escape velocity to escape into space. Escape velocity is kind of a strange name to describe the least amount of kinetic energy (motion energy) to escape the pull of Earth’s gravity. But, if we remember from earlier, Earth is still pulling on the rocket ship (and the rocket ship is still pulling on Earth). The pull is less because the distance between the rocket ship and the Earth has increased.
Escape velocity is a misleading name because it has nothing to do with velocity. Or speed for that matter. Speed and velocity are both measured in distance divided by time. The SI (International System of Units) for speed/velocity is meters per second (m/s). The difference between speed and velocity is that velocity takes into account the direction that the object traveling in as well as the speed. Escape velocity is more about the energy needed to escape the Earth, not the velocity or speed.
The nose area of the rocket is called the payload system. What is inside the payload system depends on what kind of mission the rocket ship is going on. It can have cargo, a satellite, a space probe, or maybe even humans. Below the payload system is the guidance system. This system makes sure the rocket is on the right path and going in the correct direction. It has a bunch of different equipment: sensors, radars, computers, and communication systems.
The next system is the propulsion system. It is everything below the guidance system and it makes up most of the length of the rocket ship. This is the system that initially gets the rocket off of the ground and into space. If the rocket shot upward only using its fuel, it would eventually run out of it. So, the rocket enlists the help of Earth’s gravity. One minute after the rocket has launched, it tilts sideways. By doing this, the rocket is using gravity to steer itself in the direction it wants to go into. This also minimizes aerodynamic stress on the rocket.
These are just the basics of rocket science. If we were to dig deeper into it, we would find that it is a lot more complicated. But rocket science is not as difficult to understand as some people like to make it seem. It is a hard subject, yes, but it is not impossible. If it is something you are interested in, I suggest you go and find out more about it!
Vaageesha Das is a junior at Morgantown High School.
Today’s information comes from:
- M. (n.d.). Rocket Science. Retrieved October 26, 2020, from https://www.merriam-webster.com/dictionary/rocket science; Science ABC. (2018, October 04).
- Rocket Science: How Rockets Work – A Short and Basic Explanation [Video]. YouTube. https://www.youtube.com/watch?v=jI-HeXhsUIg; TED-Ed. (2018, November 06).
- How far would you have to go to escape gravity? [Video]. YouTube. https://www.youtube.com/watch?v=YlxKh4oCKhw; Woodford, C. (2019, November 03).
- How do space rockets work? Retrieved October 26, 2020, from https://www.explainthatstuff.com/spacerockets.html.
