This is a great soundtrack! I love all the different mix of timbres you've chosen and I think they fit well. This is a great space journey too and I think you capture the theme well!
For one small constructive feedback, I like the tone of the first track and it feels like a great start to a journey, however I feel like the lower synth pans too far into the left or right sometimes, mostly because it is holding the "weight" of the track (sub/bass frequencies) and the mix feels uneven when it goes too far in the panning at times (I also listen on headphones so it is a bit more sensitive there), but despite that, I like the addition of the bass and I think it adds a nice energy to the track and conveys what you want to very well! I enjoyed the story-telling especially and the piano really ties everything together, very nicely done!