First entry! I am reading through it now. Some thoughts;

• I love adventures that have some random tables to help decide what is going on. Your table for who or what is behind the demise of the colony makes the adventure fun to replay for the DM.
• The dark secret for each PC is also a nice simple touch to set the mood!
• For the alternative start, maybe the players could be sentenced to Transportation for their crimes (And the players could make up what their crime was). Since you have some historical inspiration that might work well here.
• Good, simple ship combat system.

If you wanted to add more to the adventure, I would flesh out the search for what happened to the colony. Perhaps a few bullet points for what each of the four possible bad guys, and a small hex map or point crawl to explore.

I would run it!