The phrase "space cadet" refers to someone who is not paying attention or seems disconnected from reality, as if their mind is in outer space. It's used to describe someone who is not focused or engaged in the present moment. Full definition
It's no surprise that after his character Dodge gets abandoned by his wife (Nancy Carell), he bumps into Penny (Keira Knightley), who is just the kind of space cadet who would benefit from a grounding force in her life... especially when the world is going to end. (movies.com)
DJs from Ultra DJs will pump up the jams with a wide variety of party music, and accompanying the music will be sporadic theatrical vignettes choreographed by JACS Entertainment and dynamic digital content by Space Cadets AV projected on the industrial walls that encompass the venue. (fb101.com)
But don't check your Start menu: Microsoft hasn't included Space Cadet Pinball in any release since Windows XP, and unlike Microsoft Paint, it's probably not going to see a Windows Store reboot anytime soon. (howtogeek.com)