In the year 1999, the Earth's moon is torn from its orbit when a nuclear explosion occurs on a radioactive dump site, sending moon base Alpha and its crew on a journey through the galaxy.
- Benjamin Ouma was meant to be a series regular but people disliked working with Lon Satton so he was fired.
- Filming began at Elstree Studios. As it was under threat of closure, the entire production moved to Pinewood Studios one weekend. All the sets had to be rebuilt. As a result they were blacklisted by the unions.
- Nick Tate was originally cast as Collins. Another actor was originally cast as Nordstrom but became sick after the special milky contact lens had been made - it had to be used for the replacement actor Roy Scammell.
- ↑ Originally conceived as a new season of UFO. The plot would have had the aliens from that series trying to destroy SHADO's moon-base by knocking the moon out of orbit.