If there was a Season 4 and 5 of Star Trek The Orginal Series would you consider Star Trek The Animated Series to be the second 5 year mission of Star Trek The Animated Series.
Star Trek The Animated Series could be considered Captain James T. Kirk second 5 year mission because they had different sounds as the introduction and it said its 5 year mission instead of saying its 4th year mission and 5 year mission on screen.
Nope. The second 5 year mission was right after the events in The Motion Picture in the refit Enterprise (and was to be the basis for Star Trek Phase II, which was being planned when TAS wqas aired.
Also, seeing as the More Tribbles episode is supposed to take place not terribly long after the original Tribble episode, I thinik that its okay to place TAS somewhere during the 4th and 5th years of the original mission.
We all know that Star Trek TOS lasted from 2265-2270 with with only 3 years out of the 5 years being completed.
Although this will screw up Star Trek timeline the second 5 year mission can lead up to Star Trek The Motion Picture 2270-2275.
More Tribbles episode would take place before Star Trek The Motion Picture.