The series was created by Gerry and Sylvia Anderson, who also made "Supercar", "Fireball XL5", "Stingray", "Thunderbirds", "Captain Scarlet", "Joe 90", "UFO", "The Protectors", "Terrahawks", and "Space Precinct 2040".
Originally conceived as a new season of "U.F.O." (1970) . The plot would have had the aliens from that series trying to destroy SHADO's moonbase by knocking the moon out of orbit.
Production of the series began in 1973, but the first episode wasn't broadcast until 1975.
The series was British-made.
At the time, this was the most expensive series ever produced for British TV or for syndication.
The first-season budget was an astounding 3.25 million pounds.
Nuclear explosions on the dark side of the moon propelled it out of Earths orbit and flying through space, seen in the opening episode "Breakaway".
Moonbase Alpha contained 311 crew members.
In one episode, the crew encounters a probe that was intended to explore Jupiter. The probe was christened Voyager, which, subsequently, was the name given to a pair of probes launched from Earth in the late 1970s and did examine Jupiter as part of their missions.
Barry Morse decided to leave after the first season had ended and the explanation given for his character's (Professor Bergman) absence was that he died after his artificial heart failed.
All of the Italian male guest stars of the first season were dubbed by Robert Rietty
Season two of the series differs noticeably from the first, due to a large number of cast changes as well as set redecoration, redesigned uniforms, and a move towards more action-oriented stories.
Catherine Schell made a guest appearance in the episode "Guardian of Piri" before taking on the role of Maya in the second season.
Teresa Graves was Fred Freiberger's first choice for the role of Maya. Gerry Anderson, said his first choice was Catherine Schell.
Maya's makeup undergoes a subtle change as Season 2 goes on. Initially, she has brown ears as large "sideburns." In later episodes, her ears are normal colored, and her sideburns are thinned out.
In Britain, the second season was broadcast over the course of two years, with part shown in the autumn/winter of 1976-77, then a season break until August 1977, with new episodes running into the fall. The final two episodes were broadcast months apart in 1978.
A third season of 13 episodes was planned, with production set to start in the autumn of 1977, however low sales of the series in America forced a last-minute cancellation.
The show was criticised for its scientific errors by many, including Isaac Asimov.
Oscar winner Martin Landau (John Koenig) also stared in "Ed Wood", "Sleepy Hollow", "Crimes & Misdemeanours", "North By Northwest", and "Mission: Impossible" as Rollin Hand.
Barbara Bain (Dr Helen Russell) previously starred in "Mission: Impossible" as Cinnamon Carter, with Martin Landau.
