Telstar's Triumph

The rocket itself was a familiar bird; duplicates had blasted into space many times before. But the payload that the reliable Delta tossed into orbit last week was an astonishing piece of equipment. Built by private industry, fired aloft by the U.S. Government, the Bell Telephone Laboratories' little Telstar satellite (3-ft. diameter) opened a bright new era of long-distance communication. Very-high-frequency radio and TV stations, which are limited to line-of-sight range, suddenly saw their future reach out beyond the horizon, around the curve of the earth.

From the Sky. Although it was only 15 hours in orbit before it relayed a phone call between A. T. & T. Board Chairman Frederick R. Kappel in Maine and Vice President Lyndon Johnson in Washington, and although it has already bounced TV programs between the U.S. and Europe, Telstar is only an experimental communications satellite. A large part of its equipment is devoted to studying radiation, micrometeorites, and other potentially troublesome features of space. It was placed deliberately on an elliptical orbit (apogee 3,502 miles, perigee 593 miles) so that it could report from many different altitudes.

The wide variety of jobs requires a wide variety of electronics. The surface of the 170-lb. sphere glitters with electricity-generating solar cells. Suspended by nylon cords inside, a 20-in. aluminum canister is crammed with gadgetry. Pink plastic foam nestles around batteries, switches, sensing instruments, 1,064 transistors and 1,464 diodes. But for all the jobs that it can do, Telstar's most spectacular achievement is its radio and TV relay system. A receiver inside the canister amplifies signals received from earth 10 billion times, changes them in frequency from 6,390 to 4,170 megacycles, and sends them back through a transmitter that puts out 2 1/4 watts.

To make such low power practical, Telstar's puny little transmitter has a hefty ally on the ground. In the mountain-ringed village of Andover, Me., inside a 210-ft. sphere of inflated silvery fabric, stands a great, hornlike antenna. This mammoth electronic ear rotates, twists at odd angles, and can point toward any part of the sky. However it turns, two fair-size houses filled with electronics turn with it, and the thin, frail voice of Telstar is plucked from the sky. Fed into a maser cooled with liquid helium and sent through other intricate equipment, that voice is beefed up and transformed into TV programs or hundreds of voice signals.

The ground-based horn and its complicated collection of equipment has unlimited electricity available, but Telstar's operating power comes from its solar cells, which generate only 15 watts--not enough to keep all its apparatus operating all the time. As a result, the satellite's command obeying system, which throws electronic switches in response to coded signals from the earth, is one of its most important features. When circuits are not needed, they can be turned off to conserve power and to give the solar cells a chance to recharge Telstar's storage battery.

Sixth Payoff. Soon after Telstar was launched, NASA's global tracking network reported it on a perfect orbit. At Andover, anxious scientists heard with relief that its telemetering system was working precisely as planned, reporting no trouble at all. But during its first five 158-min. orbits, Telstar did not come within practical line-of-sight distance of the big ear in Maine. The sixth orbit was the payoff. It was 7 p.m. in Maine when the satellite raced toward the U.S. Calculations showed that it would pass close enough to Maine to hear a command.

Dr. Eugene Frank O'Neill, director of Bell's satellite-communications laboratory, reported each move over a loudspeaker. "We haven't got it yet," he said. "It will be soon. A very few minutes." Then came a pause. Said O'Neill: "We've acquired the satellite. This is probably my final report before transmission is attempted."

Now the voice of Walter L. Brown, a Bell Lab physicist, came over the loudspeaker, "The first two commands, 'A' and 'B,' will come in the next minute. They are orders to the satellite to start transmission." After another pause, Brown said deliberately: "'A' command sent, 'A' command O.K. 'B' command sent, 'B' command O.K. We're beginning to track it. The large horn has it. Signals are entering the horn. It's O.K."

The remote-control switching system was working properly; Telstar had turned on its relay apparatus and was ready for business. All eyes in the room watched as a vague light flickered on a TV screen. Then, with remarkable clarity, they saw the American flag waving briskly in front of a view of the big ear's fabric sphere. This picture, which also went to viewers across the U.S., had originated in a TV camera just outside the control room. It had jumped to Telstar, then it had come back to earth, amplified 10 billion times.

High Relay. Last week was the first time that a satisfactory TV picture ever crossed an ocean. TV signals contain so much information that they cannot be carried by submarine cables or by radio waves that carom around the globe bouncing back and forth under the ionized layers of the upper atmosphere. They must travel on microwaves, which follow paths as straight as beams of light; getting them past the curve of the earth requires a relay station high enough so that it shows above the horizon from both shores. Telstar served this purpose for a historic few minutes last week while it was sweeping across the Atlantic to Europe.

A dependable, 24-hour communications system covering the inhabited parts of the earth would require many more satellites; some signals would pass through two or more relays before reaching their destinations. The higher the satellites circle, the fewer of them would be needed. If a communications satellite were placed 22,300 miles above the earth, it would take exactly one day to complete each orbit. Thus it would keep pace with the earth's rotation and stay above the same spot on the map. Advocates of such "synchronous" communications satellites point out that three of them would be enough to cover most of the earth.

Bell Telephone, creator of Telstar, favors lower orbits and more of them. Existing rockets, say Bell's men, can lift communications satellites a few thousand miles above the earth, where existing ground apparatus can communicate with them dependably. Telstar, they argue, proved their point last week. But final decision on the kind of satellite to be used will depend on U.S. Government policy and also on foreign governments, which will surely demand voices in any worldwide system of communication. No matter which system is adopted, though, its satellites will be descendants of Bell's granddaddy Telstar.

This file is automatically generated by a robot program, so reader's discretion is required.