Lunar Gravity Assist for Electric Propulsion Satellite - For Moving Satellites to Build a Space Sunshade

Abstract: One idea to stop the increasing threat of global warming is to build a space sunshade, made up of a constellation of satellites to reflect a portion of the sunlight. These satellites need to reach an equilibrium point where they can stay in orbit with minimal adjustments. A few feasibility studies have been made in this area and the location of the equilibrium point, L1' has been found. An area that is still unclear is the best way of getting the satellites to L1'. One idea is to use electric propulsion engines , and utilizing a gravity assist around the Moon on the way to L1'. Gravity assists have mostly been performed with chemical rocket engines, so doing it with electric propulsion causes some unique issues. The goal was to find a trajectory including the gravity assist showing that this could be an effective way of transporting the satellites. To measure how effective this would be, a trajectory without a gravity assist was also created as a means of comparison. The trajectory and orbit simulations were done in the program General Missions Analysis Tool (GMAT), and the resulting trajectory took 51 days and used 83.4kg of fuel for a fuel-to-mass-ratio of 21.5%. This was a worse result compared to the trajectory without a gravity assist, which only used 80.4kg of fuel. Finally a discussion around a potential trajectory which was shown to have a much greater velocity increase was had, which would indicate that a gravity assist maneuver could provide a trajectory that does save on fuel compared to using no gravity assist.