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Attitude dynamics of a square solar sailcraft during spin-deployment

Although the motion of a spinning spacecraft with telescoping appendages and arbitrary mass properties under generic environmental loads has been characterized in past studies, specific extension of this work to the deployment of a spinning solar sail has gone previously unaddressed. Consequently, this article presents an examination of the attitude dynamics of a square solar sailcraft undergoing a spin-stabilized deployment. The analysis begins by describing the loading from solar radiation pressure that acts on the reflective sail membrane. The square solar sailcraft is then modelled as a system of geometric shapes to enable the derivation of expressions which govern the moments of inertia during deployment. Geometry and material properties of a typical 40 m square solar sailcraft are considered in the deployment simulations, where the equations of rotational motion are numerically integrated to track the pointing attitude of the sailcraft with respect to an initial reference direction. Parametric variations are examined to assess their respective impact on the pointing attitude error. The results show that an increase in the centre-of-mass/centre-of-pressure offset or a reduction of the boom deployment rate causes the most severe increase in the pointing error.