[Commander G]

Players who take 'none' for their atmosphere ought to be able to colonize Astroids since they have fewer planets than any other race design. Huge planets with no atmostphere are extremely rare. Usually no atmosphere worlds are small. It looks from the Planets.txt file that they intended to allow colonizing astroids. It must be something they decided not to implement or they have not gotten around to it yet.

With remote mining being so costly, the only thing astroids are good for is turning into planets late in the game.