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Continuous-thrust Trajectory Optimization in the Binary Asteroids System

Ashrafi, Mehnraz | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48404 (45)
  4. University: Sharif University of Technology
  5. Department: Space Engineering
  6. Advisor(s): Asadian, Nima
  7. Abstract:
  8. In this thesis, the optimal trajectories of a spacecraft in the binary asteroids system is studied. The objective functions of optimal trajectories in these system are the maximum coverage of the asteroids surface and minimum time and fuel consumption. For this purpose, the dynamic of binary system is modeled. The binary system of 1999 KW4 is selected as a case study. The ellipsoid-sphere model is a good approximation for the case of this study. In this model, the asteroids orbit in a circular orbit around each other in a spin-spin-orbit resonance configuration, in which the asteroids’ rotational velocity is equal to orbital mean motion. Then, the equations of motion of the spacecraft as the third body (which its mass is negligible) is derived within the context of the restricted full three-body problem. Coverage equations are obtained by assuming both asteroids are spherical. Finally, problem is solved by Multi-Objective Genetic Algorithm. Stopping criteria is the specified number of generations. The problem is solved with two objectives of maximum coverage and minimum fuel consumption for various total times and the Pareto fronts of each mission time is found. The results show that as the total time reduces, the Pareto front moves toward more fuel consumption. Moreover, the control acceleration, speed and coverage as a function of time are studied and compared for different scenarios. It is shown that as the mission total time reduces, more fuel is needed for maximum coverage
  9. Keywords:
  10. Genetic Algorithm ; Multiobjective Optimization ; Coverage ; Restricted Three Body Problem (RTBP) ; Trajectory Optimization ; Binary Asteroids

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