Nice start Chris, I am glad look you also enter this challenge. First of all, i love your color balance, and your idea making a space station above the old ruin. However, personally, i didn't know the rose shape before i reread your brief above. Perhaps, you should refine it more, and make it clearer.
If I were you, i would repeat your space station to create a sense of depth, maybe two other roses with a different depth in the background.
And the last, i also looking forward to look your ground city. 
