Question

What is an artificial satellite? Name any two types of artificial satellites and state their functions.

Answer 1

You could start answering the question by defining satellites. Then you could mention the classifications of satellites, namely, artificial and natural satellites. You could then explain briefly about artificial satellites then its two types. You could also name some of the satellites that you know of under the given types.

Complete step by step answer:
We could call any natural object or spacecraft orbiting a larger astronomical body, a satellite. In our solar system, all planets except Mercury and Venus have natural satellites. The size and composition of these natural satellites orbiting planets vary greatly.
In order to collect scientific information and communication man has made a device and launched into orbit using rockets, that device is known as an artificial satellite. Depending upon the purpose of the artificial satellite, its size, altitude and design varies.
Two types of satellites are:

1. Navigation satellites: They provide autonomous geo-spatial positioning. It is basically based on a global network of satellites that transmit radio signals in medium Earth orbit. You may be very familiar with GPS- global positioning systems. It consists of 24 satellites orbiting at an altitude of 20000km above Earth’s surface. They use a difference in time signals that is received from 4 satellites and then the exact location of a receiver on Earth can be calculated. Examples of navigation satellites are IRNSS 1A, BeiDou/BDS, GLONASS, Galileo, QZSS, etc.
2. Communication satellites:
   Their basic function is to relay and amplify radio telecommunications signals using a transponder. It is thus creating a communication channel in between a source transmitter and receiver at different locations of earth. Their applications are in television, telephone, radio, internet, military, etc. Examples for communication satellites are sputnik 1, project SCORE, echo 1, OSCAR 1, Telstar 1, etc.

Note: Artificial satellites can be robotic or manned. They can operate either by themselves or as a system like a satellite formation or satellite constellation. Normally they are semi-independent computer controlled systems.