This is awesome!

It particularly reminds me of the Tabletop Whale solar system map, in a really good way. I'm having a great time hunting for asteroid names that I recognize.

I do recommend that you rejigger your legend a little. I think going from solid circle to circle with a ring and back to solid circle again, then back to ring adds some visual confusion and doesn't really convey an overall increase in population size.

The void ecology idea is cool to think about. Are you going to build it all the way out, with plant analogs, herbivores, carnivores, and so on?