Solar sailing is a promising propellantless propulsion method that employs large reflective surfaces to harness solar radiation pressure for spacecraft propulsion. Despite the fact that several solar-sail near-Earth missions will launch in the coming years, there is notable lack of published studies on the uncertainties associated with missions of this kind. This thesis addresses this gap in knowledge by quantifying uncertainties related to the solar sail's optical coefficients, structural deformations, and attitude profiles. Through two uncertainty propagation methods, namely Monte Carlo simulations and the Gauss von Mises method, the study reveals the significant impact of the optical coefficient uncertainties on mission performance. The results indicate a worst-case 3-sigma uncertainty of 8.1% in altitude gain and 16.5% uncertainty in inclination gain for the NEA Scout solar sail model. Specularity coefficient uncertainty emerges as the primary driver of performance uncertainty among the analyzed optical coefficients. Structural deformation, on the other hand, exerts minimal impact. Uncertainty in the attitude profile is modelled through Ornstein-Uhlenbeck processes and is found to impact mean mission performance as well as introduce performance uncertainty. Overall, this work demonstrates the critical importance of characterizing uncertainties and provides insights crucial for mission planning and decision-making.