To solve a problem that data can not be exchanged with a ground facility during pointing in a conventional observation satellite having a pointing function.

A preceding observation satellite 1 transmits observation data to a following communication satellite 10, the observation satellite 1 is provided with an antenna C11 on the rear face in an advancing direction, and the communication satellite 10 is respectively provided with antennas D12 and E13 on the front face in the advancing direction and in a ground direction. The communication satellite 10 transmits the data received from the observation satellite 1 to a ground facility 4. Thus, the observation satellite 1 in a pointing state exchanges data with the ground facility 4 without the disconnection of a communication line or the like.