Summary

• Satellites have traditionally been used for intercontinental backbone networks, but this role has been usurped by fiber.

• Direct satellite-to-user broadcasts, pioneered by TV stations, are increasingly being used to access the Internet.

• Most communications satellites use geostationary orbits, which are so far from Earth that they result in a noticeable latency.

• New lower orbits have been tried with mobile networks. Iridium casts a shadow over their economic case, but compared to the cost of 3G licenses in many countries, a satellite network can seem inexpensive.

• Balloons and airplanes are possible alternative technologies that would provide many of a satellite system's benefits at lower cost.

• Communications satellites may ultimately extend the Internet throughout the solar system.