Even its most enthusiastic planners at Bell Telephone Laboratories never expected the sensation that Telstar caused. Although it was a deadly serious venture—one of the steps along the way toward putting together a workable satellite communications system—its success made it the inspiration, among other things, of cartoons, jokes, and a couple of popular songs. “Telstar” soon became a name recognized around the entire globe. Stories about Project Telstar appeared in newspapers in almost every language, in children’s books, in women’s fashion magazines. [Illustration: _On July 10 and 11, 1962, people on two continents saw these scenes on television at the same time, with the aid of the Telstar I satellite_] What caused all this stir in the summer and fall of 1962? The answer—now that we look back on it—seems rather clear: For the first time, the whole world discovered that satellite communications was really possible—that peoples separated by oceans could now be united by live television. Space had become an adventure, not just for lonely astronauts, but for everyone right in his living room. Project Telstar, of course, had more serious objectives: —to prove that a broadband communications satellite could transmit telephone messages, data, and television; —to test, under the stresses of an actual launch and the hazards of space, some of the electronic equipment that had been developed for satellite communications; —to measure the radiation that a satellite would meet in space; —to find out the best ways to track a moving satellite accurately; —to provide a real-life test for the special satellite communications antennas and other ground station equipment. To do its principal job—communications—the Telstar I satellite had to receive a signal from a ground station, amplify it, and then retransmit it on a different frequency back to other points on the earth. This signal had to be strong enough and good enough to be received and understood on the ground. To do its secondary job—measure radiation and other conditions in space—the satellite had to be equipped with special testing devices and had to have a means of reporting facts about the environment it encountered in space and the effects of radiation on solar cells and transistors. To let us know how well its equipment was working, the satellite had to record and transmit a large number of measurements—including such things as the temperature and pressure inside the satellite, its orientation with respect to the sun, the current and voltage in various parts of its electronic circuitry. Sending these measurements back to a ground station is called _telemetry_. To help with tracking, the satellite had to have a continuous radio beacon signal that could be easily picked up on earth.