Dual-field-of-view star sensors utilizing optical tagging approach by grating

Abstract

Star sensors play an important role in spacecraft attitude determination. It is common for the roll accuracy of a traditional star sensor with single field of view to be significantly worse than the cross-axis accuracy. Many satellites utilize two/three onboard star cameras for their attitude determination in x, y, z 3-axis. The dual-field-of-view star sensor has been proposed, which can image stars from two orthogonal directions on the same CCD simultaneously. This paper focuses on the critical issue of tagging the star spots from one of the fields of view so that these stars can be recognized. Star light from one direction is modulated by an optical grating in order to tag star images from this viewing field and distinguish them from the star images from another direction. Diffraction splits by phase gratings and amplitude gratings are compared in feasibility and complexity by numerical simulations.