How Satellites Launch into Orbit
There are over 6000 satellites currently cruising the earth’s orbit. This number is projected to accelerate in the future if we go by the current technological needs. Satellites play significant roles in communication, weather monitoring, traffic reporting, network television, and even help you to locate where things and places are located on earth. Before we learn how satellites get into orbit, let us answer the fundamental question of what satellites are.
What is a Satellite?
A satellite is anything that rotates around a planet or a star. Therefore, we can define anything that goes around the earth, the moon, the sun, or other planets as a satellite. There are two types of satellites orbiting around our planet:
Natural Satellites are naturally occurring objects that rotate around a planet or star. Apart from Venus and Mercury, all other planets have natural satellites. Examples of these naturally occurring satellites are the earth and moon. These do not need to be launched into space since they are already in space; this is general knowledge, right? Therefore, I will mention these two in passing since they are not in our scope of this material today.
Our primary concern is the other type of satellites; the artificial satellites. Artificial or human-made satellites are specially devised machines engineered and sent to space to carry out specific duties. These duties include monitoring other objects in space or observing the earth.
For a satellite to survive in space without crashing into other space objects like other satellites and space junk, they have to be launched into a specific orbit. An orbit is a path that a satellite has to follow throughout its lifespan repeatedly.
Human-made satellites are heavy machines that spend a lot of energy to get them into the earth’s orbit, where they use the gravitational pull to go round an orbit. The heaviest artificial satellite that ever graced space is NASA’s Shuttle Orbiter, which operated between 1997-2011, and weighed a massive 1,192,983lb. In later paragraphs, we shall discuss how these heavy machines can float in the air without falling back to earth, but first, let’s have a look at how they get into space.
How Satellites Launch into Orbit
We have learned that artificial satellites are engineered and sent to space to carry out specific tasks. We are also aware that these heavy machines rotate around a particular orbit. Since artificial satellites are launched from earth, scientists have to figure out how to get them into orbit. Let us take the journey that satellites take to get into outer space.
Components of Satellites that Make Them Easy to Launch in Space
Scientists have to figure out the survival of the satellites before they launch them into space. Given the aggressive radiation and high temperatures that the satellite is subjected to before it gets into its orbit, engineers make satellites adaptive in the following manner:
- Satellites are made using light, durable materials.
- They have a strong predetermined propulsion system
- It has an internal power system to power its internal functions
- Satellites have transponders that enable transmission of signals to and from earth
- Satellites have a functional tracking system
- Satellites use a light fuel called hydrazine fuel
Transportation of Satellites into Space
Satellites are transported into space using rockets. Rockets are great for satellites’ transportation because, first, their pointed noses minimize air resistance, which may slow down the movement. Second, rockets have fins that help to maintain stability during movement.
The rocket launches by burning propellants, which produces exhaust (flame and hot gases) that propel the rocket upwards. The force that moves the rocket upward is called thrust, and it should be greater than the prevailing force of gravity that will be busy pulling the rocket back to the center of the earth.
We have successfully launched the rocket carrying our satellite, and it is in motion towards outer space. The rocket needs a thrust enough to make it go at the speed of 17,800 miles per hour to make it overcome the gravitational forces and the air drag. It also needs to go past all the layers of the atmosphere. The rocket has to also tilt to a horizontal position. The rocket’s method takes up a tilted direction instead of going straight up, reduces the gravitational pull (which conserves fuel), and is called a gravity turn.
The Rocket Releases the Satellite into Space
The rocket only releases the satellite when it reaches a preset distance from the earth. This distance is set at a place where there is very thin air, which is around 120 miles away. Of course, the scientists choose areas where the air is thin to reduce the drag that would slow down the satellite’s movement.
When releasing the satellite into space, the rocket uses the Inertial Navigation Systems(INS) to put the satellite into the correct orbit. The rocket must fire the rocket with enough speed (around 8000m/s) if the satellite will keep moving. If the rate is low, then the satellite will be pulled back to earth by the dominant gravitational forces.
The satellite is also launched in a horizontal position, which is in tangent with the earth’s rotation. First, imagine if the satellite was launched vertically with a speed of over 8000 m/s. Wouldn’t it continue with an upward movement instead of following its prescribed orbit? But the more important reason why the satellite is launched horizontally is to ensure that it goes in tandem with its rotation.
Now, our satellite is moving at high speed – over 8000m/s. If no force pulls it down, it will go straight, far away from our planet, away from our predestined orbit. Moving away from our intended movement means that it would hit other objects, crash them outright. Lucky for us, the earth has a gravitational pull that pulls the satellite to itself, and since the satellite has a high momentum, the satellite keeps making rounds around the planet, one the same path over and over.
How Does Satellite Stay in Its Orbit?
The simplest way to think about a satellite’s constant movement around the planet is to have an image of an object moving along the boundary of a circle at a constant speed. A constant force is pulling it to itself simultaneously. Closer home, picture tying a stone with a strong string and swinging it around using endless energy and speed. The stone will keep rotating around you at the same rate and distance from you. In this analogy, the stone is our satellite, the string is the gravitational force, and you are the earth.
What would happen if you let go of the rope after swinging it at high speed? It would not go round and instead fly in a straight line away from you, right? The same would happen if there were no gravitational pull; the satellite would move straight out from the earth’s surface.
We have understood that the satellite gets into orbit due to the opposing forces of the satellite’s horizontal movement and the earth’s gravitational pull, which makes it possible for the satellite to move around the planet. We have also learned that other satellites are orbiting the same planet. How then is it possible for the satellite to stay in motion without bumping into other objects?
The secret is in the distance of the orbit from the earth’s surface. Satellites whose paths are closer to the earth experience a higher gravitational pull from the earth. As such, the closer a satellite’s orbit is to the planet’s surface, the faster it should go. Also, this means satellites that orbit further than the earth’s surface are slower.
So there you have it, our satellite can now keep going round and round the earth until kingdom come. If you have any questions about this topic, please hit me up in the comments section.
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