Satellite Technology

A satellite is an object which has been placed into orbit by human venture. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon. A communications satellite is a specialized wireless receiver/transmitter — receiving radio waves from one location and transmitting them to another. It is launched by a rocket and placed in orbit around the earth.

Today, there are hundreds of commercial satellites in operation around the world. Those satellites are used for such diverse purposes as wide-area network communications, weather forecasting, television broadcasting, amateur radio communications, Internet access and the Global Positioning System.

Satellites are used for a large number of purposes. Common types include military (spy) and civilian Earth observation satellites, communication satellites, navigation satellites, weather satellites, and research satellites. Space stations and human spacecraft in orbit are also satellites. Satellite orbits vary greatly, depending on the purpose of the satellite, and are classified in a number of ways.

Well-known (overlapping) classes include low Earth orbit, polar orbit, and geostationary orbit.Launched of First Satellite in SpaceThe first artificial satellite, Sputnik 1, was launched by the Soviet Union in 1957. By 2009 thousands of satellites had been launched into orbit around the Earth. These originate from more than 50 countries and have used the satellite launching capabilities of ten nations.

A few hundred satellites are currently operational, whereas thousands of unused satellites and satellite fragments orbit the Earth as space debris. A few space probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Venus, Mars, Jupiter and Saturn.