Non-Disposable and Reusable Solar Sails for Transporting Sunshades to the L1' Point

Abstract: This study evaluates the feasibility of reusing lightweight solar sails in order to transport 1.69 ' 10^6 sunshades, made out of occulting membranes with free-standing SiO2 nanotube films, to the adjusted sun-Earth Lagrange point, L1'. The purpose of the study was therefore to evaluate if this method is sufficient enough to lower Earth's average surface temperature by 1 degree C within a reasonable time frame, due to the rapid climate change, and compare the total launch mass to previously proposed methods. Two mission times of 10 years and 15 years were used, and three different starting altitudes, the GEO, MEO and LEO orbits, were investigated. The results showed that the method in this study was feasible for all combinations of starting altitudes and mission times. The solution where the mission time was set to 15 years and where the starting altitude was set to the GEO orbit, resulted in a launch mass of 11\% of the mass of the previously proposed solution. Furthermore, the investigation showed that high altitude starting orbits and long mission times resulted in a lower launch mass. However, in order to fulfill the goal of reducing the average temperature by 1 degree C in a reasonable time frame, the mission time cannot be too long. Finally, the results and calculations in this study are partially based on assumptions and simplifications, and therefore the results should be considered as approximations and not exact analytical solutions.