To quantitatively determine which artificial satellite is to be selected from among other artificial satellites that are not used at present when the use of an artificial satellite which is presently used becomes difficult due to fault, etc.

When communication is performed between the artificial satellites and a ground terminal or broadcast is performed to the ground terminal by using plural artificial satellites orbiting around the earth, for example, when a second artificial satellite 712 is out of order and the use of it becomes impossible at time 13:00, operation of the second artificial satellite 712 is stopped. And a third artificial satellite 713 with the highest angle of elevation at 13:00 among the artificial satellites in the service area is selected and operated.