Intelsat 4A F2

Launch Time
Thu Jan 29, 1976 23:56 UTC


Atlas-SLV3D Centaur-D1AR
Image Credit: USAF or NASA
General Dynamics
Status: Retired
Stages: 2
Strap-ons: 0

Mission Details

Intelsat 4A F2

Hughes Space and Communications Company, today known as Boeing Satellite Systems, built six Intelsat 4As with improved telecommunications capacity to handle the rapidly increasing traffic. These satellites for the International Telecommunications Satellite Organization (INTELSAT) had the same basic structural design as their predecessors, the Intelsat 4s, but incorporated new antenna technology to provide approximately twice the capacity of Intelsat 4. This twofold increase in capacity was attained by reusing the same frequency through antenna spot beam separation.

Each Intelsat 4A had 20 transponders (individual radio repeaters) compared to 12 aboard each Intelsat 4. Intelsat 4As over the Atlantic Ocean used 4 transponders for wide beam coverage, focusing on an area slightly larger than one-third of the world's surface--the area visible to the satellite. The remaining 16 transponders were used in the spot beam mode, where the satellite's power was concentrated on smaller selected areas within the satellite's coverage.

The Intelsat 4A had an overall height of 22 feet, 11 inches (7.01 meters), and a diameter of 7 feet, 9 inches (2.38 meters). The spacecraft's solar panels, covered with nearly 17,000 solar cells, provided primary power of 600 Watts.

Payloads: 1
Total Mass: 1,515.0 kg
Geostationary Transfer Orbit


SLC-36B, Cape Canaveral SFS, Florida, USA



10th orbital launch attempt


37th mission
1st mission of 1976
28th successful mission
3rd consecutive successful mission