Click to view a larger image

The earth horizon simulator control unit was designed to provide precision control of the position of a vane mounted on a galvanometer. When placed in front of a black body, the vane edge would simulate the horizon of the earth for a satellite mounted attitude sensor. Simulation parameters included satellite spin rate, earth duty cycle, sensor mounting inaccuracies, and presence of the sun on the horizon. A front panel meter mimicked the exact motion of the vane, which was not directly observable. This instrument was used as a final checkout test before the launch of the satellite.