Ah yes, I've already played it; sorry I didn't get back to you earlier.
I mean no disrespect when I say this, but I'm really looking for some creative execution. The premise for your mission was non-generic, I'm glad it wasn't a furball. However, there was very little creative use of sexps apart from sending messages.
GOOD points were the number of messages which led to a healthy amount of chatter, although you should use send-message for each one with chained events rather than send-message-list. The briefing and debriefings also worked, which is more than I can say for some submissions I've had.
Capital ships were also used sparingly, a virtue which even I don't often possess.
BAD points were the length of the mission, too many waves of Corsair wing to deal with - huge numbers of enemy reinforcements which seemed silly to me at the time, given that they were pirates, and the small amount of scripting for the entire mission. There was also too much black space, a few nebulae here and there doesn't cut it. Maybe you could have included the Zion asteroid bitmap you mentioned and the Nemesis jumping out towards it... that would have been a nice touch.
I suggest you download the Blackwater Ops demo and have a look at the missions in that. They are shining beacons of greatness and complexity and I've honestly seen no finer work. And not to blow my trumpet too much, but M14 in Inferno R1 is the best mission I've produced so far, have a look at that too if you don't mind climbing through the web of sexps. If you want to submit something else in the future I'll be happy to receive it. Don't lose confidence! It took me the whole of re-making chapter 1 before I could say I was skilled at FREDing.