Satellite for U.S. Service

Galaxy® IV was one of a new generation of satellites that brought C-band and Ku-band services together on the same spacecraft for American customers of PanAmSat Corporation.

The spacecraft is a version of the three-axis, body-stabilized Hughes 601 model built by Hughes Space and Communications Company (HSC) in El Segundo, Calif. In October 2000, the company became Boeing Satellite Systems, Inc. PanAmSat is the world's leading commercial provider of satellite-based communications services. The company operates a global network of 19 satellites supported by PanAmSat professionals on five continents. These resources enable PanAmSat to provide video and telecommunications services to hundreds of customers worldwide.

Galaxy IV was launched June 24, 1993, on an Ariane 42P rocket from Kourou, French Guiana. With 24 C-band and 24 Ku-band transponders it offered double the capacity of the satellite it replaced, a Hughes 376 spin-stabilized model also built by Hughes Space and Communications Company.

Stowed (left); In Orbit (right)

Galaxy IV was configured to provide coverage to all 50 United States plus the Caribbean basin, with a signal strength of 36 dBW in C-band and 45 dBW in Ku-band across the contiguous United States. On May 19, 1998, Galaxy IV suffered an on-board failure in its spacecraft control processor, the first operating Hughes satellite to suffer such a failure in orbit. PanAmSat has taken the spacecraft out of service, seven years short of its intended 12-year operational life.

All Hughes 601-now Boeing 601-spacecraft use the same basic bus design, allowing the company to realize efficiencies gained by production volume, tooling investments, and quantity buys. HSC introduced the model in 1987 to meet anticipated requirements for high-power, multiple-payload satellites for such applications as television relay, direct-to-home broadcasting, private business networks, and mobile communications.

The Boeing 601 body is composed of two modules. The first contains the primary bus structure that carries all launch vehicle loads and contains the propulsion subsystem, bus electronics, and battery packs. The second payload module is a structure of honeycomb shelves that hold the communications equipment, electronics, and isothermal heat pipes. Reflectors, antenna feeds, and solar arrays mount directly to the payload module, and antenna configurations can be placed on three faces of the bus. This modular approach allows work to proceed in parallel, thereby shortening the manufacturing schedule and test time.

Boeing Satellite Systems is the world's leading manufacturer of commercial communications satellites, and is also a major supplier of spacecraft for communications and space exploration for the U.S. government and builds weather satellites for the U.S. and Japan.