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  • Translunar Abort Trajectories for the Orion Spacecraft

    Paper number

    IAC-07-C1.I.13

    Author

    Mr. E. David Beksinski Jr, University of Maryland, United States

    Year

    2007

    Abstract

    With NASA’s renewed focus towards a permanent human presence on the moon, much work is being done to develop the Orion spacecraft. It is certain that the Orion spacecraft will take on a capsule-type form similar to those used during the Apollo missions, with similar energy level lunar transfer trajectories. Although the utmost care is taken to design a reliable spacecraft; the fact remains that unforeseen circumstances can induce emergency situations necessitating contingency plans to ensure crew safety. A readily apparent example would be the Apollo XIII mission. It is therefore desirable to define the feasibility of a direct abort to Earth from an outbound translunar trajectory. Based on velocity vector orientation and magnitude there is a region immediately following the trans-lunar injection burn where direct abort is feasible, and subsequently the same is true in close proximity to the moon. However during the mid-portion of the outbound lunar transfer orbit, the energy requirement for direct abort is prohibitively high. Thus an astrodynamic model for lunar transfer has been developed to allow for characterization of the abort feasibility envelope for any conceivable transfer orbit that could be utilized on future missions. In addition the model allows for several trade studies involving differently executed abort options, factoring in fuel margins. Four different methods of staging the required abort delta V maneuvers across the spacecraft modules were examined. An ideal abort staging is presented allowing a significant increase in available effective delta V by taking advantage of mass ratios between the Orion modules. Two separate gradient based optimization schemes were utilized; one to expedite return via any fuel in excess of that required for the abort, and one to explore the boundary region of direct abort infeasibility envelope searching for plausible abort trajectories. The first allows in decrease in time of flight for return of approximately 10The characterization and optimization of translunar abort trajectories to better define design abort feasibility requirements for the Crew Exploration Vehicle can ensure increased crew survivability in emergency situations. It is therefore the goal of this study to explore abort options for future manned lunar missions.

    Abstract document

    IAC-07-C1.I.13.pdf