May i add an extra encounter? Derelict mass - With people perhaps being able to destroy planets and all, it's not an impossibility to have some parts of it floating around the space, perhaps with some buildings, above and underground in it, all to be explored. Clues could be found about why the mass ended like this, and could be used in the main quest as well.
Also ships/meteors that have powerful hostile non-sentinent creatures on board (think Alien), might add a bit of suspence when you're not sure if there's life or not on a ship.
