Artificial satellites and uses

Artificial satellites

                 The celestial bodies revolving around a planet are called satellites. For example, the moon is a natural satellite of the earth. An artificial satellite is a man made object. When it is made to revolve round the earth, it becomes an artificial satellite of the earth. However, artificial satellites are much closer to the earth than the moon.

                They have the same time period as the earth and so they stay at the same point as seen from the earth. Artificial satellites are called geostationary or geosynchronous satellites.

              Artificial satellites stay in space for few years. The lifetime of each artificial satellite depends on its size and its distance from the earth. Artificial satellites must maintain a certain speed to stay in orbit. If an artificial satellite slows below this speed, it comes into the atmosphere and burns because of friction with the air.

              Most of the artificial satellites carry the radio transmitter and receiver. Transmitter sends signals to find the exact position of the satellites in space. Also, it sends the scientific information to the earth. A satellite's receiving equipment is turned on and off by means of signals beamed from the earth.

                Scientists have developed very powerful launch vehicles or rockets capable of carrying the satellites into the space and launch them as an artificial satellite of the earth. The movement of a rocket is based on the principle of the law of conservation of momentum and Newton's third law of motion. At present, only six countries in the world have the technology for developing artificial satellites and launching them to orbit the earth. India is one of these six countries.

Uses of artificial satellites 

           Some important practical applications of artificial satellites are given below: Artificial satellites are used for 

1. Long distance communication through telephones and internet. 

2. Transmission of television and radio programmes.

3. Locating mineral and water resources.

4. Weather forecasting and gathering more information about outer space.

5. Remote sensing. Remote sensing means collecting from a distance. This technology is used to collect information about weather, agriculture, land and ocean features including movement of fishes in oceans.