First off - WOW, you crammed a lot into that game, in a small time - Very well done. I'll try to break things down below, there's quite a lot to comment on.
First off controls- Took me a short while to get used to. Initially I didn't like the mechanic about not being able to move while shooting, but overtime I came to enjoy it, as it was.. well different, from the usual topdown space shooter mechanics. The whole idea of trading and/or mining resources- I'm a sucker for those- So I was hooked even before starting. There are obviously a lot more that can be done to the current system, but suffice it to say, I loved it. Once I got the hang of it, I Basically just moved back and forth between the starter planet (Sorry forgot the name :-( ) and the sun. Mining and selling, while killing off the odd pirate now and then. That was easy money. Now eventually when I felt brave and rich enough, I ventured beyond the portal (Of course with my hold loaded with various goods). I was.. slighlt surprised by the increase in pirates, but luckily I had already skilled up a bit in the 'safer zone', so I managed to dodge/survive, and even skill up quite a lot. Once I hit the 50.000 mark you suggested, I decided to press on, for just a little while longer, and ended the game with over 150.000. I may go back and beat that score, as it is sadly, a bit too easy to make a profit- But again I fully understand that balancing economics (And the AI, and other stuff in your game) is nigh impossible in just 48 hours.
As for the graphics- I loved your artstile for the planets, it was really great, and had a nice mood to it.
I would love to see what this game could evolve into, and would be a good candidate to have some story implemented into it as well, if one wanted to do that.
Anyways- I throughtly enjoyed playing this - So far this is probably the game I enjoyed the most this Ludum Dare, so Thanks a lot for sharing the game, and keep up the good work :-)