Mission: Impossible (Screenshot: YouTube)

On September 17, 1966, a landmark TV program debuted over on CBS: Bruce Geller’s Mission: Impossible, an action-adventure series centering on a team of highly skilled government agents. The original M:I ran from 1966 to 1973 and spawned a 1988 to 1990 revival, as well as several video games and a blockbuster film series whose sixth entry is on the way. Through all those incarnations, one consistent element has been the indelible, jazzy Mission: Impossible theme song by Argentinian composer Lalo Schifrin. Written in an unusual 5/4 time signature, supposedly to accommodate “people with five legs,” the catchy composition caught the public’s ear and just missed the Top 40 in 1967. In 1996, on the occasion of the first Mission: Impossible movie, U2’s Adam Clayton and Larry Mullen Jr. recorded their own remake of the tune, finally taking it into the Top 10 and making inroads on the Adult Contemporary and Dance Music charts, too.

By then, lots of strange things had already been done to Schifrin’s trusty theme music. Maybe the single oddest remake is a proto-mashup by composer-arranger Alan Copeland, who spliced the song’s DNA with that of “Norwegian Wood (This Bird Has Flown)” by The Beatles. Do these radically different songs, the latter being John Lennon’s confession of adultery, even fit together at all? Not really. But that doesn’t stop Copeland or his singers for a second.

Leonard Nimoy, who joined the Mission: Impossible cast in 1969 after his stint on Star Trek ended, released his debut album, Mr. Spock’s Music From Outer Space, on the Dot label in June 1967. It contained an instrumental-only remake of the Mission: Impossible theme.

And Schifrin’s theme has been quoted and sampled in numerous other compositions for decades. In 1982, for instance, Jamaican vocal group The Viceroys put a reggae spin on the theme with their song, “My Mission Is Impossible.”

It’s tough to beat the original version, even though it’s slower than fans may remember. The combination of Schifrin’s tense music and the iconic image of a lit fuse let viewers know they were in for the biggest thrills network TV was able to offer in 1966.