Slang's space cadet `an eccentric, especially one who is stuporous or out of touch with reality' evolved from  Tom Corbett, Space Cadet,  a 1950 television series depicting the adventures of a 24th-century cadet in the Solar Guides, the interplanetary police force keeping order in the Solar Alliance.
The Solar Guides are an interplanetary police force tasked with keeping order in the Solar Alliance.