Oooh, two nice ideas from Kurt and David. Thank you. I'm now thinking about combining *both* with what I have so far! The mafioso I was half thinking about being behind the scenes anyway (and have a nifty idea for a Don's HQ in a bit of (apparently abandoned) orbital structure a bit off the main station.
And the environmental angle fits really neatly with the main denouement of the adventure (if we ever get there!).