Kyle Katarn leaving one of the asteroids just before its destruction.

The two Imperial artificial asteroids were space stations disguised as asteroids. They housed military personnel and material, including AT-STs and several stormtroopers and field stormtroopers. During the battle of Altyr V, the Imperial invasion forces were dispatched from the two asteroids. Kyle Katarn infiltrated and destroyed the asteroids, effectively ensuring a New Republic victory.