Could be a bit faster
The whole time the song was playing I thought: "It could be a bit faster". So yeah, in my opinion the song should pick up a bit after the intro, in my opinion it would sound better.
But the song has a nice and indeed very spacey atmosphere, which fits nice to your description of the "Space King and his Space Dog", heh.
Also, towards the end the main melody gets a bit repetitive, so I think you should try to add some variations of it into the song.
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