I like how fast-paced and upbeat this song sounds! The fade-out at the end in particular was a really nice touch and ended the song on a good note. I think that at least in the first part of the song, the bass was a tad bit heavy (in my humble opinion) and somewhat drowned out the other instruments. You could also consider sprinkling in a little more melody in the song like you did in the middle part; the two major sections did start to get a bit repetitive near the end.
Funnily enough, I myself have had a go at this "traveling through space" type of song (I used some copyrighted motifs, however, so I couldn't post it on Newgrounds). I think your take on it was much better than mine, though, and I really enjoyed listening to it. Good job!
R4R
Aetherous 
