In Reply to: Space Cadet posted by RRC on July 12, 2008 at 23:19:
: : : Space Cadet: Term used by Jackie Gleason on the Honeymooners show. The episode is called 'TV or not to TV'. Original air date was October 1st, 1955.
: : That's interesting. I wouldn't have thought the expression was that old.
: "Tom Corbett - Space Cadet" started as a live action serial in 1950. There were also books, comics, and a radio show all pre-1955.
The Oxford English Dictionary gives both meanings of "space cadet." The first, applicable to Tom Corbett, is "space cadet, a trainee spaceman; also transf., esp. a (young) enthusiast for space travel."
The use I have heard most often, which I imagine corresponds with Jackie Gleason's meaning, is (again from the OED): "space cadet n. slang a person regarded as out of touch with reality, esp. (as if) as a result of taking drugs; a person prone to flights of fancy or irrational or strange behaviour."