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Telstar, first telecom satellite, launched 50 years ago

Martyn Williams | July 11, 2012
Fifty years ago this week a Delta rocket roared into space carrying a payload that sparked a revolution in the way the world communicates.

On its first pass over Andover, engineers were able to transmit speech and video between the receiving station and an audience in Washington, D.C. As this was happening, word came from France that the signals were being received. The British were receiving the satellite, but technical problems kept them from initially getting a useable signal. [See video of U.S. President Kennedy speaking about Telstar in 1962.]

The subsequent pass was used to demonstrate the transmission of six simultaneous telephone circuits as well as a data transmission. A newsreel of the time excitedly reports the data transmission of 1,000 words per minute. [See video of the 1962 newsreel on YouTube.]

The first television transmission from Europe came on July 11, when signals were sent from France and the U.K. and were received in Andover.

While these initial transmissions were major achievements, Telstar's primary purpose was as an experimental platform and it was used to conduct over 250 technical tests in the subsequent months.

On Nov. 23, the satellite started providing some valuable but unwelcome data.

The control channel used to command the satellite stopped responding and scientists suspected that space radiation might be messing with some of Telstar's 1,064 transistors and 1,464 diodes. At the time, the high radiation of the Van Allen belt was known, but its effects on sensitive circuitry were not well understood.

Laboratory tests pointed to certain transistors being more susceptible than others and engineers devised a control signal to bypass these components. They managed to get a control signal to Telstar when it was traveling at its closest point to the Earth and successfully regained control.

Demonstrations of TV from Europe to the U.S. resumed in January, but they were to be short-lived. The satellite again started having problems and on Feb. 21 it misinterpreted a command and operated a relay that disconnected most of the electronics from the power source.

While Telstar's life was short and its capability limited, it helped start to answer fundamental questions about satellite communications.

The same concerns, such as the effects of space radiation on electronics and the prediction of a satellite's orbit, are still relevant today with more than 300 communications satellites ringing the Earth to provide television, radio, telephone and Internet relays that touch almost all of our lives.

 

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