This is spooky. Just today i saw a CGI of how they got the mars rover on, well, Mars, and I thought "This would make a wicked MMO". You would have to have a guild formed to be able to construct all the components to build this ship and you can have milestones that are server wide to reach. First guild to space, first to the moon, first to send probes to mars, first to put a manned mission on mars and etc. I'm not sure how things could be changing enough to make a subscription model out of it but if given enough time I'm sure something can be done. Just make it similar to real life, take a year to construct a rocket to send off then 5 months to get it there.