OPTICAL SENSORS OF NETHERLANDS ASTRONOMICAL SATELLITE (ANS) .1. SUN SENSORS

The attitude-control equipment of the ANS satellite includes five optical sensors. One of their functions is to detect deviations of the satellite from the attitude in which the solar panels are most favorably oriented for the generation of energy. The sun-acquisition maneuver takes place in a number of phases, involving two kinds of sun sensors - the 'coarse' and the 'intermediate' sensors. The satellite is also equipped with a third set of sensors - the 'fine' sensors. The purpose of the fine sensors is primarily to hold the z-axis of the satellite accurately directed at the Sun; this is necessary to enable the astronomical instruments to be pointed at celestial objects. A short description of the construction and operation of these three types of sun sensors is given.