Planetary Sunshade for Solar Geoengineering: Precursor Mission for Shading the Solar Radiation Reflected by the Moon

Since the onset of industrial development in the eighteenth century, climate change has increasingly threatened natural ecosystems and human society, driving the urgent need for innovative, large-scale solutions to mitigate its impact. In particular, space-based geoengineering has emerged as a promising strategy, offering a global scale intervention. Among these methods, the Planetary Sunshade System, based on Solar Radiation Modification, aims to reduce the oncoming solar radiation, thereby mitigating the greenhouse effect and the rise of Earth's temperature. The main motivation behind this project lies in evaluating some of the critical technologies of a Planetary Sunshade System. In this perspective, a precursor mission demonstrator is designed. The mission scenario consists on deploying a solar-sail in proximity of the photo-gravitational equilibrium point L_1^*, where solar radiation pressure and gravitational pull balance. Using a CubeSat platform, chosen for its cost-effectiveness and rapid development cycle, the project aims to define optimal sizing and deployment parameters, including radius and mass, alongside essential supporting subsystems. The preliminary design proposed covers the mission analysis and deployment mechanism tested for structural resilience under operational stresses. The main contributions consist first on the CubeSat’s mass optimization, considering typical solar-sail lightness parameters from the literature. Subsequently, the orbit design is performed in the Sun-Earth-Moon Bi-Circular Restricted Four-Body Problem framework by exploiting the solar radiation pressure through attitude control. Finally, the sail deployment mechanism is presented, focusing on mechanical, electrical, and physical considerations. The mechanical analysis evaluates maximum stresses, strains, and vibrational modes to ensure resonance frequencies remain well above the operating ones of the electric motor. The electrical system is designed to ensure efficient motor operation with minimal energy consumption. The deployment mechanism employs four tape-measure booms, and a 3.8:1 scale model of the sail has been constructed to verify it can deploy without tearing.