Study On Trajectory And Overall Scheme Of Manned Mars Exploration Mission

Manned deep space exploration is a hot topic of aerospace domain in recent years. Mars is the most similar planet to Earth in the solar system, so it is one of the most attractive and ambitious objectives for future manned space exploration. Taking manned Mars mission as investigative object, this dissertation studies the interplanetary transfer trajectory design, mission integrated launch window planning, abort trajectory design, overall scheme options and assessments. The main results achieved in this dissertation are summarized as follows.Several different round-trip transfer trajectories between Earth and Mars are designed, and the fuel consumption and mission constraints are analyzed. Using Lambert rendezvous algorithm, the velocity increment distribution of Earth-Mars two-impulse round-trip trajectories in different departure and arrival time during a"big opposition cycle (15 years)"are investigated. And the results are intuitive expressed via modified Pork-chop plots. The minimum energy long-stay conjunction trajectories and short-stay trajectories are presented based on them. According to the characteristics of high-thrust and low-thrust maneuvers, the combined propulsion trajectories are proposed. An optimization approach combining Genetic Algorithm (GA) and Sequential Quadratic Programming (SQP) is proposed to design the fuel-saving and flexible trajectories of combined propulsion. Aldrin cycling cycle back and forth between Earth and Mars are investigated, in which both the Earth and Mars gravity assist maneuver are considered in the cycler trajectory design. The problem of aero capture in the terminal phase of Earth-Mars transfer is studied. The mission constraints are listed, and the entry corridor is obtained. The influences of several parameters on the trajectory shape are analyzed.The integrated launch windows of Manned Mars missions are investigated. Using effective simplified model, the distribution characteristics of Earth-Mars transfer launch opportunities are analyzed. Based on the preliminary result from the simplified model, patched conic model and high precision model are built and precise transfer trajectories satisfying the restrictions of parking orbits'altitude and inclination are obtained. And the precise launch windows of Earth-Mars transfer are obtained. As multiple assemblies in low Earth orbit (LEO) are needed for large-scale manned Mars spacecraft, the mathematics model which satisfying the rendezvous and docking constraints is built, and the corresponding launch windows from LEO are acquired. Combining the launch windows of Earth-Mars transfer and LEO assembly, the Mars mission integrated launch windows are obtained.The return trajectories after abort in case of fatal failure of manned Mars missions are designed. The investigation comprises two parts. Firstly, the characteristics of three different types of free return trajectories,"E-M-E","E-M-V-E"and"E-V-M-E", are investigated. Taking TOF (Time of Flight) and energy requirement as evaluation criterions, the feasibilities of these trajectories are analyzed. Secondly, taking the two-impulse conjunction round-trip trajectory as nominal trajectory, the strategies of emergent return in case of abort during different phases of the whole mission are analyzed. The investigation indicates that there is no perfect abort option of ideal TOF and energy requirement for both free return trajectories and emergent return trajectories. During the whole manned Mars mission, the opportunities for return in case of emergency are very limited. Furthermore, any abort trajectory needs long time for return flight and massive fuel consumption.The assessment and options of overall scenario for the human exploration of Mars are investigated. The architecture option method based on trade tree diagramming is established. A series of important elements in manned Mars mission overall scheme design space, including trajectory scheme, flight architecture, propulsion system, crew size, etc, are assessed in quality. Several scenarios are chosen for comparison. Two assessment models, one of which is a model based on IMLEO (Initial Mass in Low Earth Orbit) and TRL (Technology Readiness Level) and the other is based on MCDM (Multi-Criteria Decision Making), are used to evaluate the candidate scenarios. Both assessments indicate the all-up short surface stay chemical propulsion scenario based on LEO assembly is an ideal option for manned Mars exploration. Based on the studies of manned Mars mission, the commonalities and differences among manned lunar mission, near Earth asteroid mission, and Mars mission are comparatively analyzed. The succession among these three manned deep space exploration missions is discussed.