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Telstar One

Published on Jul 11, 2006 at 3:59 pm. No Comments.
Filed under space exploration.

Launched July 10, 1962, a small, roughly spherical, satellite going by the name of Telstar revolutionized communication technology.  Built by Bell Labs (then a division of AT&T), Telstar was a roughly spherical satellite of just over 1 meter diameter and about 77kg mass (that means it weighed 170 pounds, for those of us in the US).  It was stabalized by spinning, so there were small solar panels placed all over its surface, so that no matter how it was oriented, it would be able to get solar power.  The solar panels consisted of 3600 individual solar cells shielded with man-made saphire.  A helical antenna permitted of circularly polarized signals.  Such signals are less affected by the relative orientation of the broadcastting and receiving stations.  Transmissionn was through a series of feed horns arranged along the spacecraft’s equator.  The horns were used sequentially as the satellite rotated to bring them into position to broadcast.  A few hours after launch, (that would be later July 10 or early July 11, depending upon location on Earth), Telstar began relaying the first communications through space.
Telstar is notable for many reasons.  First, it was the first satellite developed and built solely by a private company, though it was launched on an Air Force’s Thor Delta.   Telstar was also the first active communications satellite.  That means that it received signals and rebroadcast them.  An earlier communication satellite, Echo, simply acted as a mirror for signals to bounce off of.    Telstar relayed the first transatlantic television signal, the first telephone call relayed through space, the first fax to be carried through space (the latter being very crude by modern standards).  The first television signal was scheduled for July 23 and was supposed to be a short speach made by President Kennedy.  However, as often happens with presidential addresses, the president was not ready at the appointed time.  Unlike today, though, things couldn’t just wait.  Telstar was not in an geosynchronous orbit.  Rather it’s orbit every 157 minutes.  That meant that it was in position to relay signals for a bit under a half hour at a time.  So, since the president wasn’t ready, but the satellite was already in position, the first television signal relayed through space was a few minutes of a baseball game from Chicago’s Wrigley Field.  The Philladelphia Phillies were playing the Chicago Cubs at the time.  The Phillies won, 5 to 3.
Telstar only lasted until December.  Technicians managed to reactivate it for about a month the following January, and then it died for good.  The last transmission was February 21, 1963.
A second Telstar was launched in 1965.  In 1983, the Telstar name was reactivated, and well over a dozen subsequent satellites have carried a Telstar designation.
-Astroprof

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