Study of a Crew Transfer Vehicle Using Aerocapture for Cycler Based Exploration of Mars
Balestrero Machado, Larissa
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This thesis presents the results of a conceptual design and aerocapture analysis for a Crew Transfer Vehicle (CTV) designed to carry humans between Earth or Mars and a spacecraft on an Earth-Mars cycler trajectory. The thesis outlines a parametric design model for the Crew Transfer Vehicle and presents concepts for the integration of aerocapture maneuvers within a sustainable cycler architecture. The parametric design study is focused on reducing propellant demand and thus the overall mass of the system and cost of the mission. This is accomplished by using a combination of propulsive and aerodynamic braking for insertion into a low Mars orbit and into a low Earth orbit. The requirements for propulsive and aerodynamic braking are given by the hyperbolic excess arrival speed and altitude of closest approach at the encounter with both planets, thus driving the overall design requirements for the vehicle. The thesis describes a study performed to determine the applicability of aerocapture for both Mars and Earth orbit insertion from existing cycler orbits. Furthermore, the thesis presents details on the optimal control method used to guide the spacecraft through the planet’s atmosphere and the sliding mode controller used to track the optimal trajectory. The Hermite-Simpson direct collocation is used to optimize the trajectory by targeting the atmospheric exit conditions necessary for the vehicle to reach the desired post-aerocapture orbit apoapsis and to minimize the Δ𝑣 necessary to circularize the post aerocapture orbit. Additional constraints are imposed on the trajectory such that the maximum load factor, dynamic pressure and heating rate tolerable by the crew and vehicle are not exceeded.