Very nice work
You certainly put a lot of effort into this.
I wanted to make a couple of suggestions:
1) you should place a mask on top of all other elements, to neaten up things like the border of your starfield
2) when handling graphics with long alpha or colour tweens, never go all the way to 100% alpha or 0% with any other transform - this causes the graphic to appear to warp or move. Instead, tween to 99% alpha or 1% brightness. You'll find this improves your tweens.
3) when using raster images for animatoin, make very sure that they have a transparent background. There was a disturbing effect behind your spaceships as they crashed, and I 'm not sure if this was the cause... it might have simply been bad colouring.
4) some of the voice audio was repetitive, (pilot's voice when crashing)