Extension of terminator orbits for solar sail about small bodies

Stable Sun Terminator Orbits (SSTOs) offer simple solutions and stable trajectories for solar sails with minimal control. However, their flexibility in terms of observation geometries and mission design is very limited, restricting their applicability to more demanding scenarios. Resonant Terminator Orbits (RTOs) and Quasi Terminator Orbits (QTOs), previously studied for more conventional spacecraft, represent a broader class of terminator orbits, exhibiting enhanced surface coverage capabilities and offering a more versatile approach for orbit design. By exploiting solar radiation pressure, RTOs and QTOs can become viable to solar sails, even under strong SRP effects and non-ideal sail behavior. This is done with a fixed-orientation and a variable-orientation control for the solar sail, with the main objective being to reduce the SRP effects in order to obtain the necessary conditions for terminator orbits to be obtainable. These trajectories provide new orbital options for science-driven and fuel-free asteroid mission, opening new possibilities for applications in planetary defense, in-situ resource utilization and scientific exploration, particularly for small-body missions where propulsion mass is a strict constraint.