Cutaway diagram of
a typical spin stabilised
broadcast satellite.
This diagram and some of the information has been taken from the Boeing website. There are around 60 Boeing 376 satellites in orbit around the Earth, providing tv and radio services to all 5 continents. This design is very flexible - using the basic chassis, multiple configurations can be provided. The transponders can be supplied with powers from 800W - 2000W, and a typical craft will have 24 transponders (20 active, 4 spares) which can operate in C-band or Ku-band.
Several European satellites are of this type:
Astra 2D, Astra 3A, the forthcoming Eutelsat E-Bird, Sirius 3.
Sirius 1 & Thor 1 are also of this type - these are the old BSB Marcopolo 1 and Marcopolo 2.
The Boeing 376 type was the
first communications satellite to be launched from the Space Shuttle
(Anik C3 11th November 1982).
A Palapa B satellite launching from the ill
fated Challenger shuttle 3rd February 1984.
(28th January 1986, Challenger exploded in a horrible accident 73 seconds after
launch, killing all the crew)
Picture © NASA
Two of these 376 type satellites were involved in the first Space Shuttle rescue mission! In February 1984, Westar VI and Palapa B2 were launched from the Space Shuttle. Once deployed into transfer orbit, the "perigree kick rocket motor" for the satellite package failed to fire, and the two satellites were stranded in a useless low orbit. In November 1984, the Space Shuttle was sent on a rescue mission, and successfully recovered the satellites. They were safely returned to Earth for refurbishing. In April 1990, the former Westar VI - now renamed AsiaSat 1 - was successfully launched from a Long March rocket from China, to provide telecoms services to several Asian nations.
The 2 parts of the satellite telescope for compactness during launch. Once in orbit, the body is jacked into its final position, and the reflector is deployed.
| Satellite stowed and ready for launch | In orbit, fully deployed and ready to transmit |
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An artists depiction of an operational fleet of 376's over the Americas:
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