Solar sailing with force model uncertainties and solar irradiance fluctuations

The heliocentric orbital dynamics of a spacecraft propelled by a solar sail is affected by some uncertainty sources, mostly due to the possible measurement inaccuracies of the sail film optical properties. Moreover, the solar radiation pressure, which induces the propulsive acceleration generation on the solar sail, is not constant with time, rather it is subjected to fluctuations that are hardly predictable and superimposed to the 11-year-long solar activity cycle. The aim of this work is to investigate the effects of such uncertainties on the actual heliocentric trajectory of a solar sail-based spacecraft by means of stochastic simulations, which are performed with a generalized polynomial chaos procedure. The obtained results are able to give an estimate of the uncertainty impact on the actual heliocentric trajectory and to identify the more important uncertainty sources. This is a fundamental step for obtaining more accurate theoretical and experimental information on the parameters that chiefly affect the thrust vector characteristics and ultimately the solar sail trajectory.