A way by which the satellite is kept in the correct orbit in space is known as Satellite Launching. The earth-based stations are responsible for providing proper control to the satellite moving in space.
Satellite launching is one of the crucial aspects of satellite communication. Through satellite communication, the exchange of information occurs between multiple stations through a specific channel.
Content: Satellite Launching
- Concept of Satellite Communication
- Basics of Satellite Launching
- Process of Launching
- Types of Launchers
Concept of Satellite Communication
A communication satellite is an artificial body that orbits the earth. While orbiting the satellite receives the signals coming from the transmitting ground station, performs the necessary amplification which is associated with the necessary processing and retransmits it back towards the earth that is received by the receiving ground station.
This is the basic behaviour which the satellite orbiting earth exhibit. As no communication information is originated or terminated at the satellite itself. Thus, it is not wrong to say that the satellite can be regarded as an active transmission relay and performs the action of retransmitting the received signal with necessary processing. It mainly behaves as relay towers that are generally used in terrestrial microwave communications.
The use of communication satellites at the commercial level began in the mid-1960s and has gained immense popularity with technological advancements. And due to this reason, these satellites are used in applications where information in the form of data, voice or video is needed to be transferred. These satellites provide services related to one to one communication or broadcasting. Also, it is suitable for personal communications and private network users.
As far as communication satellite is concerned, there are active and passive satellites. These two major classifications of satellites are differentiated on the basis of whether the satellite in space performs modifications or amplification of the signals coming from the earth station or not.
A passive satellite is the one that performs no amplification or modification in the signal which it receives from the ground station. This means no power is generated and only the incident power will be reflected towards a single or multiple earth-based stations. On the contrary, active satellites are a bit different because in this case, the signal which is received by satellite in space will undergo necessary modifications and then is retransmitted towards the earth stations. This means that these satellites are designed to transmit power and are controlled by the operators present on the ground.
Basics of Satellite Launching
We already know that satellite is regarded as a moving object in space that orbits the earth. The energy that causes the satellite to move is provided by fuel which is regarded as Propellant. This helps to boost the motion of satellites above the earth’s atmosphere.
Now, the question arises – how the effect of gravity is compensated?
We are aware of the fact that Newton explained that there is the gravitational force due to which every object that is thrown upward will experience a pull towards the surface of the earth. If we talk about the upward motion of the satellite then it is the result of propellent (fuel) that is present within the spacecraft. Basically, the propellent powers the spacecraft and due to its effect, the spacecraft is pushed away from the earth against gravity. More simply, it can be said that the fuel is burnt and exhaust is produced, the exhaust is nothing but the flame, hot gases, and smoke which is the result of burnt fuel.
So, the engine of the rocket puts down the exhaust to the ground. This is regarded as the action force and in this response to action force, the rocket starts to move in the upward direction. The motion of the rocket in the upward direction is the reaction force.
It is to be noted here that in order to maintain the upward motion of the rocket so that it is not pulled by the earth’s gravity, a sufficient amount of propellants will be needed. As when sufficient propellant is provided then the thrust (a type of force) pushes the rocket up more than the gravitational force that is pulling the rocket down.
Process of Launching of Satellite
Satellite launching is defined as the process by which the satellite is placed in the proper orbit. The operation of the satellite in this duration is controlled by the earth stations. However, rockets or spacecraft plays a very crucial role in the launching process as propellants on which the rocket operates are somewhat fragile in nature.
The launching of the satellite is divided into four stages, given as follows:
- First Stage: This stage includes the availability of a rocket and fuel that is used to lift the satellite from the ground to space.
- Second Stage: This stage includes the presence of smaller rockets in the launch vehicle. When the first stage is completed then it ignited and contains its own fuel tank.
- Third Stage: This stage of the launch vehicle forms a connection with the fairing of the satellite. The fairing is a protective shield of metal present around the satellite.
- Fourth Stage: Once the satellite begins to move towards space then after entering the region which is out of Earth’s atmosphere, the satellite will get separated from the upper stage of the launch vehicle. After getting separated, the satellite will be in the transfer orbit and through this orbit, the satellite will be sent to upper regions into space.
When the required height is obtained in the space then the subsystems of satellite-like solar panels and communication antennas will get unfolded. At this time, the satellite takes its desired position in the orbit and further performs the necessary services to the world.
Types of Satellite Launch Vehicle
With the help of the launch vehicle, the satellites get placed in an adequate orbit. The launch vehicles are basically multi-stage rockets and thus are mainly classified as:
1. Expendable Launch Vehicles (ELV): These are one-time use launch vehicles that get destroyed once the satellite leaves the vehicle in order to orbit in space. The expendable launch vehicles will get burned in the atmosphere or will fall in the sea after the successful launching of the satellite in space.
It contains 3 stages where the first and second stages keep the satellite at a height of about 50 miles and 100 miles. While at the third stage the satellite will get placed in the transfer orbit. Once the satellite will reach the transfer orbit then the task of the launch vehicle will get completed and the various parts will get destroyed by themselves generally by falling to the earth.
2. Reusable Launch Vehicles (RLV): This category of launch vehicles offers reusability and so can be used various times for launching satellites in space. RLV works in a way that it simply comes back to the earth once satellite starts moving in space. Sometimes it is given the name, space shuttle.
Like the first and second stages of ELV, the space shuttle behaves in a similar manner. However, in the third stage, the satellite is inserted with a cargo bay and the satellite gets ejected from the cargo bay when the RLV attains an elevation of around 150 to 200 miles. Once this height is achieved then the shuttle will be fired thereby placing the satellite in the transfer orbit and after this the RLV comes back to the earth and can be used as and when required.
This is all about Satellite Launching.