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Asteroid field attempt massive fail- need help

Okay so, I make asteroids easy, I want to make an asteroid field. I have been watching videos and looking at tutorials for days now. Curve brush, micro mesh, insert micro mesh and i just cannot figure this out. Maybe my computer does not have enough memory or I am missing some steps here?

I want to simulate an asteroid field circling a planet ( the planet i paint in photoshop ) I have tried all sorts of ways to do this and I can’t seem to make it happen. I really just want to make one curved (line) of asteroids so i can render and bring in to photoshop in order to create the layers of asteroids to make the asteroid field.

Does anyone know a way to do this inside zbrush? Even if it is just in 2d?, without having to place each asteroid one by one?

here are a few examples of what i have already done with the asteroids i have made:
m.o.d
oriziongate
pandera

but what i want to do is more like this:
Asteroid field around planet

or something similar, maybe i am just putting too much detail into my asteroids? Photoshop and Zbrush are the only programs I own to do this as some people have said use 3dmax or maya but for as powerful as zbrush is i believe i should be able to do this some how.

Can anyone please help me?