Effect of the total solar irradiance variations on solar-sail low-eccentricity orbits

Solar photon sailing is based on the radiation pressure of the total solar irradiance (TSI). This note analyzes the effects of the actual irradiance on low-eccentricity orbits as an introductory work to much more complex cases such as sailcraft-Mars rendezvous. Two special orbits are considered: (1) a circular warning orbit and (2) a transfer orbit between Earth and Mars. It turns out that TSI fluctuations can cause large perturbations to these types of solar-sail trajectory.