First Transmission of Television Image via Satellite


This is the television picture that was bounced off an orbiting balloon satellite on April 24. The signal to the balloon was sent out by a field station of Massachusetts Institute of Technology (MIT) from Camp Parks, California. It was picked up by the Millstone Hill laboratory at Westford, Massachusetts. The land points are about 4345 kilometres apart. The satellite was 1600 km above the earth.


TV Image 'Bounced' Off Echo I Satellite



Echo 1 sits fully inflated at a Navy hangar in Weeksville, North Carolina

The quality of the first picture was not good. It looked somewhat like a badly adjusted home TV receiver, "snow." However, the picture that was shown to reporters - a lettered card with the initials MIT was entirely recognisable.


Echo 1 was placed in orbit around the earth at an altitude about 1400km above the earth. One reason for the poor quality was the wear and tear that the satellite was subjected to in space since it was launched from Cape Canaveral.


Skin Much Punctured


The metalized plastic skin about half as thick as the transparent plastic on a cigarette packet had been punctured repeatedly by space particles and dust. The once perfect sphere ended up looking like the skin of a prune. Radar measurements had revealed that it had shrunk a good deal from its original diameter.


Because of the uneven surface strength of the reflected signals was only half that of the satellite's first hours in space when a recorded radio message by President Eisenhower was bounced from it.


A second big obstacle was the task of tracking such a small, fast-moving object simultaneously with transmitter and receiver beamed only one-tenth of a diameter wide. The tracking was made doubly difficult by the Echo's irregular path.


Heavier satellites were able to travel in a more stable orbit. Their orbits can be measured and predicted days and weeks in advance.


Echo, as it was so large in area, yet so light in mass gets pushed around by the slightest pressure. Actually the pressure of sunlight, which is about equal to the weight of a salted peanut, is enough to change its orbit from circular to elliptical at frequent intervals. Thus its orbit could not be predicted more than a few hours in advance.


The transmission of pictures by the Lincoln Laboratory team was made possible by a US Air Force grant. It was accomplished by very high frequency - 8.50 megacycles - transmitting and receiving equipment.


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