The beginning of the satellite communications era began with the publication of a paper written by Arthur C. Clarke in 1945. The paper described human-tended space stations designed to facilitate communications links for points on Earth. The key to this concept was the placement of space stations in geosynchronous Earth orbit (GEO), a location 35,786 kilometers (22,300 miles) above Earth. Objects in this orbit will revolve about Earth along its equatorial plane at the same rate as the planet rotates. Thus, a satellite or space station in GEO will seem fixed in the sky and will be directly above an observer at the equator. A communications satellite in GEO can "see" about one-third of Earth's surface, so to make global communications possible, three satellites need to be placed in this unique orbit.

Clarke envisioned a space station, rather than a satellite, as a communications outpost because he...