Communications Satellite

The Syncom 4 communications satellite was launched from the space shuttle Discovery. Modern communications satellites receive signals from the earth, amplify them, and retransmit them, providing television, telefax, telephone, radio, and digital data links around the world. Syncom 4 follows a geosynchronous orbit—that is, it orbits at the same rate at which the earth spins, keeping the satellite in a fixed position over the surface. This type of orbit enables uninterrupted communication links between ground stations.