How Satellite TV Works – Geostationary Satellites – Satellite Technology
This short video explains how Geostationary Satellites stay in a geostationary orbit allows the reception of satellite TV around the world.
Satellites operate from a geo stationary orbit, which is why they are named Geostationary Satellites. This orbit brings together properties, which allow the satellite which has reached its orbit to begin to rotate around the Earth at great speeds but to maintain a relative position with respect to the Earth.
The Geostationary Satellites orbit is 22,236 miles directly above the earths equator. At this altitude it takes a satellite 24hours to orbit around the earth. The same length of time as it takes the earth to spin on its axis. This means that from earth the satellite appears to be stationary. (The moon takes approximately 28 days to orbit the earth). The concept of a geostationary orbit was written about by Arthur C. Clarke in 1945 and hence is often referred to as the “Clarke Belt”.
As the satellites in a geostationary orbit are directly above the equator they have a latitude reading of 0 degrees. People often refer to a satellite by its longitude reading. For example the satellites that are used to broadcast Sky and Freesat from are often known as Astra 28.2; Astra refers to the company that operates the satellites and 28.2 degrees east is there longitude location in space.
This is a big advantage for communications because the geo stationary satellite is seen from the Earth as a fixed point in space. This aspect gives rise to one of the key properties of geo stationary satellites: their ability to link two points on Earth which are separated through large distances. In fact, it is possible to provide communications coverage for the entire planet with only three communication satellites properly situated in geo stationary orbits
Arthur C. Clarke made the first scientific description of the properties of a geo stationary orbit in 1945. The line in the Sky where the various satellites are located in the sky is called The Clarke Belt.
With the large growth in recent years of the television and communications industries, the Clarke Belt has become a crowed piece of space, especially near America and Europe. When a satellite has completed its operational life it is then moved into a different orbit out of the way. This is commonly known as the “Graveyard or Disposal Orbit”.