On May 7, 1963, the Telstar II satellite was launched into an elliptical orbit almost twice as large as that of Telstar I, ranging from an apogee of 6697 miles to a perigee of 604 miles. The new satellite circles the earth once every 225 minutes. The higher altitude provides Telstar II with longer periods when it is visible at both Andover and ground stations in Europe, and keeps it out of the high-radiation regions of space for a greater part of the time. The satellite itself is much the same as Telstar I, except for a few minor changes that make its weight 175 rather than 170 pounds. Its radiation measuring devices have a greater range of sensitivity, and there are six new measurements to be reported back to earth. Telemetry can now be sent on both the microwave beacon and, as before, on the 136-megacycle beacon. To help prevent the kind of damage that occurred in the transistors of Telstar I’s command decoders, Telstar II uses a different type of transistor, in which the gases have been removed from the cap enclosures that surround the transistor elements. A simplified method of operation for the giant Andover horn antenna is now in operation, with the autotrack alone being used for precise tracking and pointing. Telstar II’s first successful television transmission took place on May 7, and a new series of technical tests, radiation measurements, and experiments in transoceanic communications has begun. How the Telstar Satellite Works A lot of facts and figures sometimes lead only to confusion, but these pages may help make things clearer. Here you can see—step by step—exactly what happens during a typical pass of the Telstar satellite over the Andover ground station: [Illustration: {Telstar satellite at work}] 1 _The satellite comes over the horizon._ 2 _The command tracker, knowing from computer data the satellite’s approximate location, begins to search for its continuous 136-megacycle beacon. A quad-helix antenna (four long spirals) tracks the satellite to an accuracy of one degree._ 3 _When the satellite is located, the command transmitter turns on the satellite’s transistor circuits and telemetry. The ground station then checks on the satellite’s operating condition, as reported by telemetry._ 4 _The command transmitter then turns on the satellite’s traveling-wave tube, which starts the transmission of a 4080-megacycle beacon signal._ 5 _The precision tracker—an eight-foot parabolic dish (known as a Cassegrainian antenna) mounted on a pylon—locates this beacon and tracks it to within one-fiftieth of a degree._ 6 _The horn antenna’s autotrack mechanism, which is pointed by both the precision tracker and data from magnetic tapes, locates the satellite’s beacon signal._ 7 _Now the horn antenna locks onto the satellite, with the autotrack continuing to make fine adjustments in pointing the horn._