A method of and apparatus for determining and controlling the inertial
attitude of a spinning artificial satellite without using a suite of
inertial gyroscopes. The method and apparatus operate by tracking three
astronomical objects near the Earth's ecliptic pole and the satellite's
and/or star tracker's spin axis and processing the track information. The
method and apparatus include steps and means for selecting preferably
three astronomical objects using a histogram method and determining a
square of a first radius (R.sub.1.sup.2) of a track of a first
astronomical object; determining a square of a second radius
(R.sub.2.sup.2) of a track of a second astronomical object; determining a
square of a third radius (R.sub.3.sup.2) of a track of a third
astronomical object; determining the inertial attitude of the spin axis
using the squares of the first, second, and third radii (R.sub.1.sup.2,
R.sub.2.sup.2, and R.sub.3.sup.2) to calculate pitch, yaw, and roll rate;
determining a change in the pitch and yaw of the artificial satellite;
and controlling on-board generated current flow to various
orthogonally-disposed current-carrying loops to act against the Earth's
magnetic field and to apply gyroscopic precession to the spinning
satellite to correct and maintain its optimum inertial attitude.