Attitude Determination of a Small Spinning Satellite

81-85One magnetometer when placed in a spinning satellite in such a way that its axis makes an angle γ= tan-1 with the spin-axis gives successively three mutually independent components of the earth's magnetic field after each 120ᵒ rotation. This technique is utilized in determining the spin rate and the angle between the spin-axis and geomagnetic vector. This angle does not uniquely define the spin-axis in space but three such angles evaluated in successive orbits fix up the spin-axis and hence determine the attitude. By introducing one sun detector, the satellite attitude can be determined instantaneously by noting the magnetometer output at the time of a pulse from the sun detector