Star Trek: The Animated Series were added to the cast—claiming that Sulu and Uhura were of importance as they were proof of the ethnic diversity of the 23rd century and should not be recast. Nimoy also took this stand as a matter of principle, as he knew of the financial troubles many of his "Star Trek" co-stars were facing after cancellation of the series. Koenig was not forgotten, and later wrote an episode for the series, becoming the first "Star Trek" actor to write a "Star Trek" story. Koenig wrote "The Infinite Vulcan", which had plot elements from the original "Star Trek" episode "Space Seed"
Star Trek: The Original Series show. "Star Trek"s first-season ratings would in earlier years likely have caused NBC to cancel the show. The network had pioneered research into viewers' demographic profiles in the early 1960s, however, and, by 1967, it and other networks increasingly considered such data when making decisions; for example, CBS temporarily cancelled "Gunsmoke" that year because it had too many older and too few younger viewers. Although Roddenberry later claimed that NBC was unaware of "Star Trek"s favorable demographics, awareness of "Star Trek"s "quality" audience is what likely caused the network to retain the show after the first and second seasons. NBC