Working of Satellite:
A satellite (human-made) is a self-contained communication system with the ability to receive signals from one Earth station and transmit those signals back to the other Earth stations. The reception and transmission of the signal are happening with the help of a transponder present at the satellite end. The communication system is the main component of a satellite which includes the antennas and transponder. Also, some other important components are the power system, which includes the solar panels that provide power, and the propulsion system, which contains a rocket to propel the satellite into the desired position of the Earth orbit.
A satellite, which has to operate continuously in the Earth’s orbit over its entire life span, needs internal power to the source to operate its entire electronic systems and communications payload. The main source of power is sunlight that is utilized by using solar panels. A satellite also contains backup batteries on board to provide power when the sunlight is blocked by other objects like Earth. These batteries are charged by the current generated by the solar panels when there is sunlight.
The entire circuitry and structure of a satellite are specially designed to operate in a wide temperature range — 150 °C (−238 °F) to 150 °C (300 °F). Also, these all are covered to prevent space radiation.
Satellites operate in three orbits:
Low Earth Orbit (LEO): These satellites are positioned at an altitude between 150 to 1500 Km (100 to 1000 miles) above Earth. To cover the entire Earth 20 or more than 20 LEO satellites are required.
Medium Earth Orbit (MEO): MEO satellites are positioned at 10,000 to 20,000 Km (6,300 to 12,500 mile) away from the Earth’s surface. 10 or more MEO satellites can cover the entire Earth.
Geostationary Earth Orbit (GEO): The GEO satellites are present at the highest altitude of the Earth’s orbit. These are present at 35,786 Km (22,236 miles) above the Earth’s surface where they complete their one rotation of the Earth in 24 hours. And because of this GEO satellites remain fixed over one spot with respect to Earth. Only Three GEO satellites can cover the entire Earth whereas we are using more than three satellites in GEO orbit to provide more precise and accurate data.