Mission design applications in the Earth-Moon system: Transfer trajectories and stationkeeping

Pavlak, Thomas A. M.S.A.A., Purdue University, May 2010. Mission Design Applications in the Earth-Moon System: Transfer Trajectories and Stationkeeping. Major Professor: Kathleen C. Howell. A renewed interest in the Moon over the last decade has created a need for robust mission design algorithms in the Earth-Moon system. Strategies for computing orbits within the context of the circular restricted three-body problem as well as higherfidelity ephemeris models are adapted to fulfill a variety of mission objectives. To support future scientific and communications objectives, periodic and quasi-periodic orbits in the vicinity the collinear L1 and L2 libration points in the Earth-Moon system are discussed. Differential corrections algorithms are presented to compute the orbits and to transition them to the higher-fidelity ephemeris models. A controlpoint stationkeeping strategy is modified to maintain several L2 libration point orbits and preliminary stationkeeping costs are computed. As a result of the discovery of water ice at the lunar poles, these regions have emerged as a focus of future manned mission design efforts. The use of the circular restricted three-body problem as a preliminary design tool for this problem is explored. Families of planar and out-of-plane free return trajectories are computed in the three-body model and are included as part of a four-phase bi-elliptic transfer to the lunar poles. A differential corrections scheme to compute multi-burn Earth-Moon transfers in a higher-fidelity ephemeris model is developed as well. This algorithm offers flexibility in the mission design process and is used (i) to reduce total maneuver costs in a baseline trajectory, and (ii) to explore innovative solutions. A long-term goal in this analysis is an improved understanding of the dynamical environment in this region of space.