Abstract: A sun-synchronous sun ray blocking device for use in a spacecraft having a directionally controlled main body, such as a low inclination angle earth (as well as other planets) orbit spacecraft, that is, a three axis stabilized spacecraft having north, south, east, west, earth and anti-earth panels defining a spacecraft main body. The north and south panels, on which the spacecraft equipment with high heat dissipation is usually mounted, have their planar normal axes relatively parallel to the spinning axis of the earth. Normal to each of the north and south panel, a solar panel loaded with solar cells is extended and is directly rotating about the same axis. The solar panels are controlled in such a way that the solar cells side of the panels always faces the sun.