Where happy spaceman goes! (4,3,4)

I believe the answer is:

over the moon

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'where happy' is the definition.
'over the moon' can be an answer for 'happy' (I've seen this in another clue). I'm unsure of the 'where' bit.

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for over the moon that I've seen before include "So happy" , "Severely restricted" , "Jumping for joy?" , "Sent" , "Ecstatic" .)

I've seen this clue in the Sydney Morning Herald.

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