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1	Electric propulsion of satellites as an alternative for implementation of a sunshade system Arfan, Maheen, Bonnier, Isabelle January 2022 (has links) As an alternative solution to global warming, this thesis explores the possibility of aspace-based geoengineering scheme that may prove worthwhile to implement in parallel toother environmental efforts that help mitigate impact of climate change. One suggestionof a geoengineering solution is deploying a large number of sunshades in the vicinity ofthe first Lagrange point of the Sun-Earth system, and this prospective sunshade projectwould serve to shield Earth from incident solar radiation. This thesis is an extension ofa feasibility study for the implementation of this large-scale mission, and has a focus oncomparing electric thrusters to solar sailing as a means of propulsion. Background onelectric propulsion systems and spaceflight mechanics is provided. The investigation wasperformed by defining the spacecraft configurations, and then computing trajectories toa point of escape from Earth and from there to the final equilibrium point.Our results show that in order to meet the propellant demands of the electric thrusters,the launch mass would need to increase by around 15-25 % compared to the solar sailingimplementation, equating to around 1010 kg. Nevertheless, electric propulsion could stillbe a beneficial choice since it would allow shorter transfer times for each shade whichreduces the radiation exposure and subsequent degradation of the spacecraft’s systems.It was found that the transfer time with electric propulsion would be about one-half orone-fifth that of solar sailing, depending on spacecraft parameters. Additionally, electricpropulsion allows a much lower initial parking orbit, and while this would increase the ra-diation exposure it would also reduce the launch costs due to the higher payload capacityto lower altitudes. However, electric propulsion of this scale require prior advancementsin xenon or other inert propellant extraction methods and possibly a wide-scale construc-tion of air separation plants. Geoengineering Sunshade system Electric propulsion Orbital mechanics Sub-lagrange Physical Sciences Fysik
2	Communication For a Space Sunshade System Granberg, Moa, Silfverberg, Nikolina January 2024 (has links) By placing millions of space sunshades, of the order of 104 m2 at the sub-Lagrangian point L1',between the sun and Earth, solar radiation can be reduced enough to achieve the necessary temper-ature reduction to enable a slow down of the global warming. The vast amount of space sunshadesposes significant challenges on the communication system, as the probability of interference, whichcan distort information, increases with the number of simultaneously communicating units.This thesis aims to design a potential structure for the communication system that minimizesinterference as much as possible. To reduce the number of simultaneously communicating units, thesunshades are arranged in cell formation, where a mother is placed in the center with daughtersaround that only communicate with their specific cell mother. Direct communication betweenthe Earth and space sunshades is not possible as the interference from solar radiation can causesignificant distortion on the signals. Therefore, relay satellites are placed in orbit around thesub-Lagrangian point L1' at a sufficient distance to avoid the effects of solar radiation. Thus, thecommunication between the mothers and Earth is instead routed via the relay satellites. Sincecommunication between such a large number of entities in space has not been investigated before,this approach could provide a possible basic design framework for designing such infrastructure inthe future. Satellite communication Relay satellite Lagrange point Sub-Lagrange point Space sunshade Sunshade system TT&C Transfer frame Telemetry packet Communication scheme Ka-frequency band Forward error correction Modulation Channel capacity Bandpass modulation Quadrature phase shift keying Code division multiple access Cell configuration Interference Link budget Link margin Solar exclusion zone Sun outage Satellites in multiple layers Physical Sciences Fysik

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Electric propulsion of satellites as an alternative for implementation of a sunshade system

Communication For a Space Sunshade System