If you have zero blocker asteroids you will receive four blocker asteroids. Are used to keep your opponent from moving through or into a space occupied by your blocker asteroid. Your communication cores and drone satellites cannot pass through or land on your blockers asteroids. If your communication core or drone satellite is in a space next to your blocker asteroid in any direction you can use your move to swap places with that blocker asteroid. Blocker asteroids are placed into gameplay after the communication cores and drone satellites have been placed, and are placed anywhere on the game board when it is your turn and use one turn during game play. You can have a maximum of four blocker asteroids. Blocker asteroids move one space at a time and use one turn. After all four blocker asteroids are out of inventory you will receive four new blocker asteroids.