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.

The purpose of the study is to evaluate the possibility of using gridded ion thrusters as a means of attitude control for a solar sail as a part of the sunshade project, which aims to place 10^8 solar sail sunshade spacecraft, each with an area of about 10 000 m^2, at the Sun-Earth Lagrangian point L1 in order to reduce Earth's global temperature. Two types of solar sail sunshade spacecraft were studied. The first type, referred to as the sunshade demonstrator, had an area of 100 m^2 and a mass of 10 kg, and the second type, referred to as the full-sized sunshade, had an area of 10 000 m^2 and a mass of 90 kg. To determine the significance of using ion thrusters for the attitude control system, the mass of the required fuel, as well as the total mass that had to be added to the spacecraft to implement the attitude control system, was calculated. Two types of journeys were studied for each spacecraft type: starting from Low Earth Orbit (LEO) to L1 and from Geostationary Orbit (GEO) to L1, respectively. The results showed that the duration of the journey of the full-sized spacecraft was about 570 days from LEO to L1 and 370 from GEO to L1, respectively. The required amounts of fuel for the respective journeys were 580 g and 15 g, respectively, and resulted in a total additional mass of 7.8 kg and 7.2 kg, respectively.

Solar sails are an innovative propulsion mechanism for space exploration, harnessing the momentum of photons from the Sun to propel spacecraft. As material science advances and launch costs continue to fall, opportunities utilising the novel characteristics of solar sails become more and more feasible. Due to the inherit connection between mass and acceleration, it is of great importance to reduce mass to gain acceleration. This thesis investigates the structure of solar sails and provides an analysis of the forces they encounter. The study examines the forces acting on circular solar sails in space, as well as the unique challenges they face on Earth and during the launch phase. The membrane and supporting composite structure is analysed using mathematical models in MATLAB in order to develop and optimize structures for strength and reduced mass. Dimensioning forces were found and a preliminary structure discussed. By understanding these forces, it is possible to optimize the design and deployment of solar sails, paving the way for more efficient space missions. / Solsegel är en innovativ framdrivningsmekanism för rymdforskning som utnyttjar fotoners rörelsemängd från solen fotoner för att driva rymdfarkoster. I takt med att materialvetenskapen utvecklas och uppskjutningskostnader fortsätter att sjunka, blir möjligheterna att anv¨anda solsegels unika egenskaper alltmer genomförbara. På grund av det naturliga sambandet mellan massa och acceleration är det av stor vikt att minska massan för att öka accelerationen. Detta examensarbete undersöker strukturen hos solsegel och ger en analys av de krafter de utsätts för i olika stadier under dess livscykel. Studien granskar de krafter som verkar på seglen i rymden, samt de unika utmaningar de står inför på jorden och under uppskjutningsfasen. Membranet och den stödjande kompositstrukturen analyseras med hjälp av modeller i MATLAB för att utveckla och optimera strukturer med avseende pästyrka och vikt. Genom att förstå dessa krafter är det möjligt att optimera utformningen och utplaceringen av solsegel, vilket banar väg för allt mer effektiva och unika rymduppdrag.