The show, which ran on NBC from 1955 to 1958, featured dramatized versions of short stories by writers liked Robert Heinlein, Frederic Pohl, Issac Asimov, and Ray Bradbury (including a not very subtle adaptation of his creepy "Mars is Heaven" (05/08/55)). While the show had different stories each week (it was not a serial), the opening was always the same:

Countdown for blast-off. X Minus 5, 4, 3, 2, (pause) X Minus 1, Fire! (Sound of engines firing) From the far horizons of the unknown come transcribed tales of new dimensions in time and space. These are stories of the future. Adventures in which you will live in a million could-be years on a thousand maybe worlds. The National Broadcasting Corporation in cooperation with Astounding Science Fiction presents . . . . X Minus One!