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Investigation of Saturation Dynamics in GPS Allocated Orbits for Removal and Injection Mission

Shahsavani, Sadaf | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47154 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Fathi, Mohsen; Malaek, Mohammad Bagher
  7. Abstract:
  8. The number of GPS satellites, which are spent their life and work, have been increasingly on the rise. Hence with knowledge of debris numbers, we can get an estimate of collisions risk probability and functional interference of active satellites in the future time. In this study, by using three methods, least-squares, RBF and ANFIS and statistical data the growth pattern of retired satellite numbers has been expected in the future. Numbers estimated by curve fitting methods in 2014 have been compared to the number of satellites disabled and growth estimation error has been analyzed by two models. Solar activity, the sun's radiation incidence angle on the satellite solar panel and the Earth's magnetic field have been shown as important parameters that influence the performance of the satellite and as a result, its failure. It was shown that there is inverse relationship between satellite lifetime and the normalized integration of the surface under the values of the angle of the sun on solar panels diagram. In this study, the dynamics of GPS satellites removal orbit and the impact of long-term and secular perturbation sources have been simulated using STK software. A geometric method to get the most collision risk and functional interference probability has been introduced. Also All GPS satellites injection and disposal strategies has been analyzed for cost and performance aspects
  9. Keywords:
  10. Global Position System (GPS) ; Retired Satellite ; Effective Perturbation ; Ecceutricity Growth ; Satellite Number Estimation ; Collision Risk

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