State-Space Approach to Computing Spacecraft Pointing Jitter

Pointing jitter refers to unwanted line-of-sight motion incurred by a pointing system over a time window of specified duration. Jitter acts to smear images and degrade the quality of science obtainable from camera-type instruments. A recent mathematical expression for finite window pointing jitter involves the frequency-domain integral of a rational polynomial multiplied by a transcendental weighting function. Because of its complexity, the expression is generally evaluated using numerical integration. The main contribution of this paper is a state-space method for evaluating the frequency-domain integral. In particular, an exact state-space expression is developed that can be evaluated by computing a matrix exponential and solving a Liapunov equation.