Rockets are one of mankind’s most mind-blowing inventions, but the average person does not know much about them or how they work. For example, how do rockets work in space where there is nothing for them to push against?
But it’s a common misconception that rockets need to be pushed against something to work. Rockets work in accordance with Newton’s third law of motion. The gas that they expel allows them to move forward, even if there is nothing for them to be pushed against.
Keep reading below as we get into more detail on how rockets work in space.
What is Space?
First things first: let’s get a handle on what we mean when we talk about space, and then we can go on to figuring out how rockets work in space.
When you’re fastened into your rocket and whistling your way to the heavens, you won’t come across any road signs that say “Slow Down! Space Ahead” There is no clear-cut border that denotes the transition from Earth’s surface to the void that lies beyond it.
This is due to the fact that gravity (the force that is responsible for the formation of Earth’s atmosphere by drawing air molecules towards our planet) extends to infinity. To put it another way, the atmosphere of Earth fades away gradually, becoming indistinguishable from the beginning of space.
Space is typically considered to begin approximately 100 kilometers (60 miles) above the surface of the Earth. This arbitrary threshold is frequently referred to as the Kármán line. At this altitude, conventional aircraft have a difficult time producing enough lift to remain aloft.
You might think that space is quite a distance away, yet a hundred kilometers is not quite as far. If you were driving a car at the speed limit on the highway, it would take you about one hour to get there; however, if you were riding in a rocket, it would take you just three minutes to get there, which is approximately twenty times faster.
How Do Rockets Work in Space?
It is often believed that when a rocket takes off, it somehow exerts force on the launch pad or the air around it in order to gain altitude. People are therefore forced to wonder how rockets work in space, where there is neither space nor anything against which they can push. However, this is a widely held misunderstanding. Allow us to explain.
There is a combustion chamber located on the interior of a rocket, and that chamber is responsible for lighting the fuel and oxidizer on fire. When these two burn, they turn into an extremely hot gas that has an appetite to expand at a rapid rate. However, because the chamber is stiff and there is just a single little hole in it, the gas is expelled through the hole and out of the rear of the rocket.
According to the third law of Newton, for every action, there is an equal and opposite reaction. When the rocket expels those gases from its rear, it gains the same amount of forward momentum.
This is simple enough for you to test out. Try to locate a rolling office chair and position it on a flat, even surface. Take a chair, get a basketball or soccer ball, and bring your feet up so they are not touching the ground. Toss the ball as far away from yourself as possible with as much force as you can muster. Both you and the ball will speed off in the opposite direction.
You don’t go flying off just because the ball is exerting pressure on anything; that has no bearing on anything. Of course, there is a very, very slight effect that the ball pressing on the air has, but it is much too insignificant to be noticed, and it fails to explain the speed with which you move along the floor.
Two factors will determine how quickly you can zip off, taking into account both your own weight and the weight of the chair:
- How heavy the ball is. Tossing something away increases your speed proportionally to its mass.
- The speed at which you can throw the ball If you throw the ball more forcefully, you’ll get further away in less time.
The propulsion system of a rocket consists of expelling extremely hot gases at a very high rate of speed from the back of the rocket. The gases are not exerting any force on anything else. It works on the same premise as when you toss a ball away.
If a rocket expels a specific quantity of gas at a specific speed from its engine, then the rocket will generate the same amount of force regardless of where it is located: on a launch pad on Earth, on the surface of the moon, circling a planet, or traveling through intergalactic space. In any case, the gases are not exerting any force on anything because both they and the rocket are acting according to Newton’s third law.
How Do Rockets Turn in Space?
There are primarily three ways that rockets and spacecraft in general can change course when they are in space. These are as follows:
Hypergolic Thrusters
Hypergolic fuels, used in thrusters, ignite upon coming into contact with one another. This allows for the use of small, non-ignitable engines that can produce little thrust and, depending on their placement, can alter the rocket’s or spacecraft’s trajectory.
Reaction Wheels
Reaction wheels, which are also known as gyroscopes, function according to the law of the conservation of angular momentum: when you spin a flywheel in space in one direction, the rest of the spaceship moves in the opposite direction as a way to conserve the entire angular momentum of the system—the spacecraft itself. It’s merely a wheel with motors turning it in the opposite direction to create angular momentum.
Rockets rarely use reaction wheels for navigation because they are often lagging, only work in the vacuum of space, and don’t offer a lot of change in direction. Rather, reaction wheels are more commonly seen in other spacecraft and satellites.
Gimbaling of Engines/Thrust Vectoring
Engines are frequently mounted on gimbals, which enable them to essentially direct their thrust in multiple directions by letting the engine move in a variety of positions. In most cases, this will provide the necessary guidance for a rocket’s passage through the atmosphere in regions where hypergolic thrusters and reaction wheels are unable to function to their full potential.
The rocket’s engines can produce thrust in a variety of directions, which allows it to alter its course.
This method is very efficient because the rocket’s engine generates a great deal of power; however, it cannot compete with the accuracy of hypergolic thrusters or reaction wheels. Many contemporary rockets, including the widely used Soyuz R7, have engines designed for precisely this purpose.
Conclusion
Although there is widespread confusion about how rockets work in space, once you get the hang of it, it’s quite simple to understand. We hope the explanation in this article was able to clear up your confusion.
