concert band Interstellar Horizon for Concert Band

Interstellar Horizon for Concert Band is my biggest and most ambitious project yet! It is my first fully completed concert band piece. It is to convey the beauty and danger of interstellar space travel in about 5 different phases.

I'm going to be real critical of this piece, not for bad reasons but because this piece has a lot of potential.  I see a sea of great possibilities .

I'll start with the biggest criticism.  You have no counterpoint in this piece.  The first hint of it is around 3:40.  That's WAY too long without a countermelody.  You want to keep your audience and your music engaged.

Next, what grade level (difficulty) are you writing for.  If this piece was shorter, this could work for young bands.  A more experienced band wouldn't touch this as it stands.  Also, it's too long for young bands. Are you familiar with the difficulty scales?

Last thing, try to avoid the static nature of whole notes.  Look at Granger especially his "Irish Tune from County Derry."  He does a lot of displacement with the chords to keep it it moving.  Although it's not traditional counterpoint, the movement of the chords works as a great substitute.

@maestrowick's assertion that there is no counterpoint is correct and a critical downfall of this piece. What it does is not only keep an audience engaged, but can expertly call back to other themes. The big concert Bb minor sections would be perfect for such. Homophony is great for grounding an idea, but past that, there's a lot of room for expansion in developing ideas; polyphony is the best way to do this. 
However, I disagree on the static whole notes assertion, in certain places. While I don't particularly like the chord structure you use sometimes (crossed voices, no bass, etc.), it can create a lot of atmosphere. I do think you need to improve on the structure of when and how you use them. In the beginning, parallel octaves between melody and bass, especially in that register sound awkward, especially resolving to a new tonic of another chord. Things like that are always needing to be heeded, but the whole notes in and of themselves are not incorrect, though near the end, you could lighten it up a bit, perhaps work with suspensions and resolutions more.
BUT having a really fast ostinato with whole notes, while I can see what you're going for, is not a melody, and a huge waste of kinetic energy you chose to put in potential energy. 
Finally, this doesn't captivate me in the way you want it to. It does in other terms, but it's not very otherworldly, mostly because of the simple structure of chords and melodic lines. Things need to change. Things need to be strange. Things need to live and grow like the universe.

Congratulations on an ambitious work; fine tuning time!