The quest for the ultimate vacuum tube

In July, 1962, the Telstar 1 satellite took an enormous leap toward the globally connected world we now take for granted. It relayed from space, for the first time ever, live television images and telephone calls between continents: specifically, a ground station in Andover, Maine, and other stations in England and France. It accomplished this feat thanks to a microwave repeater that had at its heart a slight but powerful vacuum device known as a traveling-wave tube. The 30-centimeter-long, glasswalled electron tube was at the time the only device capable of boosting a broadband television signal with enough power to cross an ocean. Solid-state devices just weren´t up to the task.