Solar-sail navigation: Estimation of force, moments, and optical parameters

Determining a solar sail's mathematical model on the ground is an inherently difficult task. Uncertainties in the sail shape are always present because the sail's precise curvature and surface structure may change after deployment in space. These changes may invalidate previous measurements and computations. For accurate navigation, it is essential that the postlaunch sail mathematical model is estimated. In this paper, we provide a methodology for estimating the force and moment generated by a sail of arbitrary, but constant, shape based on in-flight data. This is accomplished by finding the force and moment tensor coefficients defined by the generalized sail model, which analytically models the characteristics of solar sails with arbitrary shapes. Several data sampling examples are studied to determine the attitudes that allow for better estimation of the sail's force and moment coefficients.