AT&T's Advanced New Communications Satellite
||2.16 m (7 ft 1 in)
||2.74 m (9 ft)
||6.84 m (22 ft 5 in)
||653 kg (1438 lb)
beginning of life
In August 1980, American Telephone and Telegraph Company contracted with Hughes Space and Communications Group for three of the new Telstar satellites, all Hughes 376 models. Hughes Space and Communications Company is now Satellite Development Center. Telstar 3A was launched on a Delta rocket 28 July 1983. Telstar 3C was launched on the space shuttle 30 August 1984, and Telstar 3B was launched on the space shuttle 17 June 1985. The satellites replace those AT&T leased from Comsat General Corporation, a subsidiary of Communications Satellite Corporation.
Telstar 3A is in geosynchronous orbit at 96 degrees West longitude, Telstar 3C is at 86 degrees West longitude, and Telstar 3B is at 125 degrees West longitude. The satellites and related ground facilities serve customers in the contiguous United States, Hawaii, Alaska, and Puerto Rico.
The new satellites have 10 year design lives, as opposed to 7 year lives for earlier satellite models. Life extension is due chiefly to the use of improved nickel-cadmium batteries and the introduction of solid state power amplifiers in place of traveling wave tubes for 18 of the 30 high power transmitters.
The Boeing 376 spacecraft is spin stabilized, a concept developed at Hughes and used in its communication and scientific satellites for more than 20 years. The Boeing 376 utilizes two solar cell covered concentric cylinders, of which the outer extends downward in space to greatly increase the solar generating power capacity over the models it replaces. Advanced solar cells made by Spectrolab, a Hughes subsidiary, are used. The solar cells develop 917 watts at beginning of life. A folding dual reflector, which deploys in space, is located at the forward end of the spacecraft.
The spacecraft is launched with the main communications reflector and the outer cylinder stowed, a configuration that makes it possible to launch either with expendable rocket boosters or from the space shuttle. The compact stowed configuration allows the spacecraft to stand upright in the shuttle cargo bay; occupying a minimum of linear space is a cost effective use of the shuttle.
The spacecraft are 7 feet, 1 inch (2.16 meters) in diameter. In their stowed configuration they are 9 feet (2.74 meters) in height. Height with antennas and the telescoping solar panel deployed is 22 feet, 5 inches (6.84 meters). Weight in orbit is 1438 pounds (653 kg).
Like their predecessor satellites, the Telstar 3 satellites operate at 6/4 GHz (C band). Simultaneous long distance telephone call capacity is 21,600. The satellites furnish voice, video, and high speed data services.
The satellites each have 24 transponder channels that can be switched by ground command to various combinations of regional coverage spanning the continental U.S. and Hawaii, Alaska, or Puerto Rico.
Coverage beams for the Telstar 3 satellites are formed by polarization selective surface reflectors offset by feed horn arrays. One array is for horizontal polarization and the other is for vertical.
A payload assist module attached to the spacecraft performs the conventional third stage rocket function, inserting the satellite into its elliptical transfer orbit. The apogee motor that places the satellite into near geosynchronous orbit is a Thiokol Corporation Star 30 solid propellant rocket used on all HS 376 spacecraft.
As the contract with AT&T also called for, Hughes Space and Communications Group supplied a satellite control center at an existing AT&T facility at Hawley, Pennsylvania. The center houses equipment used for on-orbit satellite monitoring and control as well as tracking and command during transfer orbit. The center additionally furnishes computation capability for orbital determination. The facility operates through three existing 98 foot, 5 inch (30 meter) antennas.
In addition, Hughes installed a satellite control earth station at Hawley with a 42 foot, 8 inch (13 meter) antenna, RF equipment, and automatic computer controlled test equipment designed to track the satellite during its transfer orbit and to perform stationkeeping duties.
The satellite control station is augmented by an alternate station at Three Peaks, California, with equipment like that at Hawley.
Hughes provided training and customer documentation and was responsible for the satellites' initial operation.