As originally conceived by executive producer Irwin Allen, the weekly, 60-minute Lost in Space was to have been a relatively serious sci-fi opus called The Space Family Robinson. Set in 1997, the series focused on astrophysicist Dr. John Robinson (Guy Williams), his wife, Maureen (June Lockhart); and their children, Judy (Marta Kristen), Will (Bill Mumy), and Penny (Angela Cartwright), all of whom were blasted into space on the "Jupiter II." Placed in suspended animation, the family was on a mission to colonize a planet in the Alpha Centauri star system four light years from Earth. But the Jupiter II's computer malfunctioned, the ship was thrown way off course, and the family woke up several years ahead of schedule to find themselves lost in space. In the series pilot, the main characters were joined by Jupiter II's pilot, Don West (Mark Goddard) -- and no one else. CBS was impressed by Space Family Robinson, but the network insisted upon a title change and also demanded that a villain be added to the proceedings. Thus the project was re-christened Lost in Space, and the pilot episode was reshot so the Jupiter II's malfunction was due to the treachery of an enemy spy named Dr. Zachary Smith (Jonathan Harris), who had sabotaged a robot aboard the ship and programmed it to kill the Robinsons and abort the mission. Unfortunately for Dr. Smith, he was accidentally trapped in the Jupiter II and hurtled into space along with the Robinsons, hence the new title of the pilot show, "The Reluctant Stowaway" (portions of the original pilot, which was top-heavy with expensive special effects, were edited into the series' first five episodes). It had been planned that both Dr. Smith and the killer robot would be eliminated from the series after its inaugural five-episode story arc, but CBS saw potential in both characters and insisted that they be retained.
The network's decision proved to be a brilliant one in terms of the series' ratings: gradually morphing from a cold-hearted assassin to a supercilious, cowardly buffoon, Dr. Smith was easily the show's most popular character -- next to the now-benign robot, who turned out to be a veritable cornucopia of useful technical information and also came in handy when warning the Robinson family of impending danger. Between the Lost in Space pilot and the series proper, it had also been decided to drop the original intention of serializing the episodes, though each installment ended with a coming-attractions "cliffhanger." Finally, what started out as a straightforward, straight-faced endeavor gradually evolved (or, in the minds of less enchanted viewers, devolved) into a semi-humorous exercise in Batman-style camp, replete with such colorful guest villains as a scurvy space pirate (with a robotic parrot), a Brandoesque space-cruising cycle bum, and even a huge talking carrot! The first season, filmed in black-and-white, found the Robinsons stranded on an uncharted planet. The series switched to color for the second season, in which the "Jupiter II" was repaired and the space travelers blasted off -- only to be marooned on another mysterious planet. Season three did a more efficient job of living up to the series' title, as the Jupiter II hopped from planet to planet, galaxy to galaxy, though no closer to "home" than before. The 83 episodes of Lost in Space have flourished in syndication and on such cable-TV services as The Sci-Fi Channel ever since the series' initial CBS run, which lasted from 1965 to 1968.