On April 6, 1965, the first operational and commercial communication satellite was launched. The Early Bird (or Intelsat 1) provided regular telecommunications and broadcasting services between North America and Europe. Other Intelsats followed soon. On July 20, 1969, the landing of the first human on the Moon was broadcasted live through the global network of intelsat satellites to over 600 million television viewers.
Satellite communication are a necessity to have global coverage. Live transmissions over long distance is not possible on the round earth, because radio, television and telephone transmissions travel in straight lines. Today, there are more than 2000 satellites in orbit. Future satellite communication systems will have more bandwidth and an increased service life.
A satellite communication system consists of a ground and a space segment. Satellite receivers on the ground can be direct-to-home (DTH) satellite equipment, mobile reception equipment in aircraft, satellite telephones, or handheld devices. Large data communications sometimes use Very Small Aperture Terminal (VSAT) networks, which is a two-way satellite ground/maritime station with a dish antenna is smaller than 3 meters. Data rates range from 4 kbit/s up to 16 Mbit/s. VSATs are used to transmit narrowband data like financial transactions, or broadband data (satellite internet accesss, VoIP, Video).
Operational satellite communication foresees three types of services: telecommunication, broadcasting and data communications. Compared to land-based systems, satellite communication is particularlly of interest for "point-to-multipoint" communications like broadcasting. Isolated areas use satellite communications often for telecommunication and internet access, since the investments on the ground are reasonable. Besides regulare use, satellite communications are particularly of interest during natural disasters or emergencies when land-based communication services are down. Mobile satellite communication systems can be deployed for emergency communication use.
sources: http://en.wikipedia.org/wiki/Communications_satellite, http://en.wikipedia.org/wiki/Very-small-aperture_terminal, http://www.britannica.com/EBchecked/topic/524891/satellite-communication/288218/Satellite-applications
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