Any machine or planet which orbits around another planet or star is a satellite. In order to continue, let us clarify the difference between natural satellites and artificial satellites. Moon is the natural satellite since it orbits around our planet Earth. Even, we will be glad to know that our Earth is also a natural satellite of the Sun. So with this, we can conclude that any planet revolving around another planet or star is a natural satellite. A planet or star can have multiple natural satellites.Our Earth has only one natural satellite i.e. the moon. While on the other hand, we have artificial satellites which are man-made and we intentionally launch them into space to revolve around Earth or another planet. Each of these satellites is sent to perform specific tasks. We will explore more about Artificial Satellite.

Image of Earth's Satellites

Credits-NASA

Actually we can cover much larger area with satellites since they are outside of the surface of Earth. This leads to collection of more data at a higher speed which is a definite plus point for using satellites.

Today artificial satellites serve a large number of purposes.

Types of Satellites with their Purposes:

  • Communication Satellite – They serve the purpose of telecommunication. Earlier when we send TV signals , they travel in straight line and hence can’t travel long because it disappears into space because of Earth’s curve .Even providing telephones wires for longer distances was overhead. Nowadays, TV signals and phone calls are sent to satellites and in turn they return data very quickly. They actually perform the task of processing information from source to receiver.
  • Navigational Satellite – When you use GPS (Global Positioning System) in your smart phone, don’t forget to remember that it is result of using satellites. Navigational satellite uses radio time signals transmitted to enable user access its exact location using a electronic receiver. It also enables user to synchronise its time according to its location. This global coverage system is called Global Navigation Satellite System (GNSS).
  • Weather Satellite –   These satellites monitor Earth’s weather and climate conditions. Not only Earth, it can be used to monitor other planets weather conditions.
  • Earth Observation Satellite –  These are used to have a regular observation of Earth which helps us to create maps and monitoring environmental conditions.
  • Astronomical Satellite –  These are used by astronomers to have observations of distant planet or galaxies, and have better vision than telescope used at Earth. Actually they have the advantage of flying above the clouds, molecules and dust which can block view from Earth’s ground surface.
  • Space Stations – They are designed for human beings to live on outer surface of the earth. They can be used to live for weeks, months, or even years.

Spaceships or Space Craft are also satellites used to carry human beings to and from space. Tether Satellites are used to connect two satellites usually by a thin cable called a tether.

ERS 2

A full-size model of the Earth observation satellite ERS 2

How does Satellite orbits Earth?

At once it seemed imaginary to make an object revolve around another planet, but it is achieved by balancing its speed with Earth’s gravitational force. If it doesn’t get balanced, it will fall back to Earth’s ground surface or go into space.

Why don’t Satellite Collide?

Yes they can collide. Although when a satellite is launched by rockets, they are placed into an orbit designed to avoid collision with other satellites already orbiting around the earth. It can result in collision when satellite changes its orbit. It has actually happened in February 2009, when two communication satellites collided. One of them belonged to USA and other to Russia.

What Happens after End of Satellite’s Use?

Nowadays satellites have the option of de-orbiting which is controlled by satellite operators. When satellite’s life is ended, they are moved to different orbit called graveyard orbit and it is done to lower the possibility of collisions with other satellite. Although historically, satellites did not have the option of de-orbiting due to budgetary constraints.

The first artificial satellite is Sputnik 1 , launched by Soviet Union in 1957. Nowadays thousands of satellites have been launched to serve different purposes.

I hope you liked this introduction article on satellites and please share your thoughts about this vast topic.

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