Patent ID: 7227114
Filing Date: 2007-06-05
Classification: B64G

Abstract:
1. A method of determining the attitude (φ, θ, Ψ) of a spacecraft, the method comprising: a) sensing the projections (xmi, ymi) of a plurality of stars on an optical star sensor mounted on the spacecraft; b) providing a reference focal length (f c) determining the angular values of the attitude of the spacecraft relative to the stars by solving a system of equations which has as its input data in particular the projections of the stars (xmi, ymi) on the sensor and the reference focal length of the sensor; the method being characterized by introducing, as unknowns in the system of equations, at least one parameter (D in step c), by determining said parameter(s) (D in such a manner that taking said focal length error parameter(s) into account as unknowns in the system reduces the uncertainty introduced by incomplete knowledge of these errors on the results for the values of the attitude angles (φ, θ, Ψ) of the spacecraft.