A satellite is any object which revolves in an orbit around a planet. This object may be natural like the moon that orbits the earth, or manmade.
The artificial satellites are usually closer to the earth than the moon, and are designed to perform specific tasks.
* Many TV channels are brought to our homes by Broadcast Satellites, which are used to transmit television signals from one place to another.
* The daily weather forecast available on many news channels is based on information provided by Weather Satellites. Meteorologists also analyse data provided by these satellites to make long-term predictions about the weather.
* Telephone conversations as well as data can be sent around the world quickly using Communications Satellites. These satellites usually have hundreds of transponders; a device that receives a telephone conversation at one frequency amplifies it and transmits it back to earth on another frequency.
* The use of Military Satellites was very much in evidence during the wars in Afghanistan and Iraq. Besides monitoring communications, missile launches, enemy movements and providing photographs of targets, these satellites are also used to guide missiles to their targets. Even during peacetime, these spy satellites are used for monitoring activities such as development of new weapons systems.
* Most modern planes and ships use information provided by Navigational Satellites, to help them navigate.
* The Hubble Space Telescope and the International Space Station are two examples of Scientific Satellites.
* While the equipment carried by the satellite depends on the task it is designed to perform, satellites have several things in common:
* They are built around a frame or bus, which must be strong enough to carry the equipment as well as survive the launch.
* Electrical power is usually obtained from solar cells, storage batteries or fuel cells.
* Computers control the different equipment and also monitor conditions on the satellite.