At any time during your Action or Reaction you may use one or more of your faceup Colony Ships by flipping them facedown. For each Colony Ship used this way, you may move one Population Cube from your Control Board to any empty Population Square in a Sector you Control. Each Population Cube you move must be taken from the Population Track that corresponds to the color of the Population Square it is being placed on. Colony Ships are the only way to move Population Cubes to Sectors!