Forum:Continue after story ends?

Can I continue playing after the main story ends? I didn't play the "Bringing down the sky" mission during the main play-through because I was expecting to be able to go back to my ship after the main story ended and play "Bringing down the sky" and look for stuff I hadn't found yet etc. This doesn't seem possible. Am I missing something, or am I just screwed? (my last save that would allow me to get back to the ship is like 10 playing hours before the end :. I'm on the PC version, if it matters...