How are satellites used?

Communications satellites
Communications satellites are the most common. If you have cable TV or a satellite dish on an outside wall, the programmes you see certainly come via a satellite. Telenor owns two broadcasting satellites and leases capacity on other satellites, all sending from an orbit position at 1° West latitude.

Communications satellites relay more than TV programmes. They also provide telephone, Internet, data and communications for ships at sea, support search and rescue services, and perform other functions. Intelsat is a company that operates more than 20 communications satellites, of which the largest can carry a hundred thousand telephone conversations at the same time!

Navigation satellites
If you have used a GPS-receiver, you have used a navigation satellite. GPS is the abbreviation of Global Positioning System, an American network of satellites in various orbits around the Earth. You can use a GPS-receiver to find your location with a precision of a few metres. Europe is now building its own navigation satellite system, Galileo, scheduled to start service in 2008.

Earth observation satellites
An Earth observation satellite can be made for a specific task, such as monitoring land or sea areas. Some Earth observation satellites, such as Envisat, are made to perform several monitoring tasks at the same time. These satellites are advanced laboratories for acquiring data, which are sent to Earth for processing and analysis by scientists round the world. The results are invaluable in the monitoring of global warming, pollution and other environmental aspects.

Meteorological satellites
A meteorological satellite is an Earth observation satellite used for the specific task of monitoring wind, cloud formations and other variables that permit predicting weather. The weather reports you see on TV usually are based on data from many satellites.