“Space: the final frontier. These are the voyages of the starship Enterprise. Its five-year mission: to explore strange new worlds, to seek out new life and new civilizations… to boldly go where no man has gone before!”

It would be hard to find many TV shows as wildly influential as the original series of”Star Trek,” which inspired a devoted fandom, several spinoffs of varying quality, a string of films, and most recently an alternate-timeline reboot directed by J. J. Abrams. And despite the late-sixties bright colors and miniskirts, there’s a bright-eyed yet intense quality to the series — it’s a smart, well-written series with a few duds, headed by a trio of memorable and lovable characters.

In the twenty-third century, mankind has spread out among the stars, and established a Federation of like-minded worlds. The starship Enterprise is part of their Starfleet division — and it does pretty much everything, from fighting hostile aliens like the Klingons and the Romulans, ferrying diplomats and alien dignitaries, and exploring planets with weird and freakish creatures on them (including a furry creature that sucks salt out of its victims).

The captain is James T. Kirk (William Shatner), who is assisted and guided by his two trusted friends, the logic-driven, half-Vulcan science officer Spock (Leonard Nimoy) and the crusty, blunt-spoken doctor Leonard “Bones” McCoy (Deforest Kelley). With the faithful crew of the Enterprise behind them, they travel through time, encounter godlike aliens, fall prey to some weird diseases (including one that makes you drunk!), get caught in countless planetary wars, deal with a suspiciously large number of crazy/evil computers, and encounter countless strange creatures (a rock monster, brains in jars, a hostile lizard-man, flying brain cells, Jack the ripper, tribbles…).

Yes, it has those bright colors, beehives and chintzy sets that you expect from a late sixties show, especially a science fiction one. But what made “Star Trek: The Original Series” such an enduring show was that it was a depiction of a brighter future, full of exploration and wonder, without becoming too starry-eyed to take seriously. And it had a good balance of “Big Moral Message” stories (“racism is stupid,” “war is bad,” “don’t trust computers blindly”) and solid sci-fi stories that featured some truly weird, out-there alien life forms.

Simply put,”Star Trek: The Original Series” tended to have very well-written, intense stories that relied on a mix of action (usually involving Kirk losing part of his shirt), well-written dialogue and plenty of powerful emotion (a guilt-ridden starship captain becomes obsessed with destroying a machine that killed his crew). This allowed some of the stories that would otherwise seem rather silly (Spock getting a pancake-sized alien cell embedded in his back) to have some serious tension, but not in a way that precluded some actual humor (the entire episode about tribbles — chirping little furry balls that reproduce exponentially — is side-splittingly funny, especially when poor Kirk gets buried alive in them).

It also has one of the most cohesive casts ever to be seen on TV, even though actors like Nichelle Nichols, George Takei and Walter Koenig were underused. For all the gags about Shatner’s acting, he plays Kirk as a man of both brains and passion — he’s driven and emotion, with a love for his ship, his crew and the unexplored crannies of the galaxy that rules his life. But he’s also intelligent and canny, and more than once we see him outwitting a foe, whether it’s making a primitive gun by hand or playing the ultimate bluff against a vast alien ship.

And he has uniquely solid chemistry with Nimoy and Kelley, so that you can really believe that these three characters are fast friends who bicker, joke and advise each other… well, mostly Bones and Spock snipe at each other, while Kirk sits there smiling. Nimoy gives a brilliant performance as the half-Vulcan, half-human Spock, struggling with the emotions that his Vulcan nature doesn’t allow him to express, even though his relationship with his people is rather tempestuous. Kelley plays McCoy as the exact opposite — a fiery Southern doctor whose determination to do the right thing sometimes clashes with his duty. Yes, he boozes it up while on duty, but who doesn’t want a doctor like McCoy?

Flaws? Well, like any TV show, “Star Trek: The Original Series” had some dud episodes, often involving space hippies, Abraham Lincoln and brain theft. And some of the attitudes towards women are… seriously problematic, especially in the final episode. The series briefly dabbled in the idea of a female first officer, and Nichelle Nichols’ Uhura is depicted as strong, gutsy and smart when she gets to do something (which is admittedly rare), but it’s still heavily weighed towards the men.

Few TV shows have had the impact on nerd culture that “Star Trek: The Original Series” has had, whether it’s transporting to a parallel reality or catchphrases that everyone misquotes. Despite some episodes that veer off into the silly and/or stupid, it’s still an excellent, enjoyable series with a bright, idealistic view of the future.