Once an individual asteroid has been mined clean of resources, you can convert the mining base into a military or observation base. The tricky thing is that the asteroids are constantly orbiting the sun. This can be a mixed blessing. This, coupled with the placement of the two planets, helps to orient the player. Since the asteroids are in orbit, you can place bases on them while they're on your side of the system and then let their momentum carry them into the enemy's backyard.
Asteroids also interfere with detection equipment so they're a useful place to hide.
But be careful about parking your bigger ships in the asteroid belt as a little carelessness can lead to a fatal collision. O.R.B. offers five separate levels of units. Each unit is ranked in terms of armor, speed, maneuver, firepower and cost. First and foremost among the ships is the space station in orbit around your home planet. Here you can build new units, research technologies and upgrade existing ship classes.