if i may be as bold as to make a suggestion for your next version:
some kind of lander would be the logical next step, since much of the work actualy done by an orbinaut is done during the descent to the target body (be it lunar or Martian (or Venusian in the case of a probe))
it will be great to see what you guys could come up with, perhaps a universal lander, capable of landing on either the moon or mars? i have a couple of ideas for this, but im sure a good long think could yield interesting results and methods
its good to see this still in development, its looking like a fine piece of work!