X Minus One was a half-hour science fiction radio drama series broadcast from April 24, 1955 to January 9, 1958 in various timeslots on NBC.
Initially a revival of NBC's Dimension X (1950-51), the first 15 episodes of X Minus One were new versions of Dimension X episodes, but the remainder were adaptations by NBC staff writers, including Ernest Kinoy and George Lefferts, of newly published science fiction stories by leading writers in the field, including Isaac Asimov, Ray Bradbury, Philip K. Dick, Robert A. Heinlein, Frederik Pohl and Theodore Sturgeon, along with some original scripts by Kinoy and Lefferts.
Included in the series were adaptations of Robert Sheckley's "Skulking Permit," Bradbury's "Mars Is Heaven", Heinlein's "Universe" and "The Green Hills of Earth", " Pohl's "The Tunnel under the World", J. T. McIntosh's "Hallucination Orbit", Fritz Leiber's "A Pail of Air", and George Lefferts' "The Parade".
The program opened with announcer Fred Collins delivering the countdown, leading into the following introduction (although later shows were partnered with Galaxy Science Fiction rather than Astounding Science Fiction).
The series was canceled after the 126th broadcast on January 9, 1958. However, the early 1970s brought a wave of nostalgia for old-time radio; a new experimental episode, "The Iron Chancellor" by Robert Silverberg, was produced in 1973, but it failed to revive the series. NBC also tried broadcasting the old recordings, but their irregular once-monthly scheduling kept even devoted listeners from following the broadcasts. (source: wikipedia)