One of the most important metrics characterizing an atmospheric entry trajectory in preliminary design is the size of its predicted landing ellipse. Often, requirements for this ellipse are set early in design and significantly influence both the expected scientific return from a particular mission and the cost of development. Requirements typically specify a certain probability level (6-level) for the prescribed ellipse, and frequently this latter requirement is taken at 36. However, searches for the justification of 36 as a robustness requirement suggest it is an empirical rule of thumb borrowed from non-aerospace fields. This paper presents an investigation into the sensitivity of trajectory performance to varying robustness (6-level) requirements. The treatment of robustness as a distinct objective is discussed, and an analysis framework is presented involving the manipulation of design variables to effect trades between performance and robustness objectives. The scenario for which this method is illustrated is the ballistic entry of an MSL-class Mars entry vehicle. Here, the design variable is entry flight path angle, and objectives are parachute deploy altitude performance and error ellipse robustness. Resulting plots show the sensitivities between these objectives and trends in the entry flight path angles required to design to these objectives. Relevance to the trajectory designer is discussed, as are potential steps for further development and use of this type of analysis.


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    Title :

    Trading Robustness Requirements in Mars Entry Trajectory Design


    Contributors:

    Conference:

    AIAA Atmospheric Flight Mechanics Conference ; 2009 ; Chicago, IL, United States


    Publication date :

    2009-01-01


    Type of media :

    Preprint


    Type of material :

    No indication


    Language :

    English





    Trading Robustness Requirements in Mars Entry Trajectory Design

    Lafleur, J. / American Institute of Aeronautics and Astronautics | British Library Conference Proceedings | 2009


    Mars Pathfinder Atmospheric Entry Trajectory Design

    Spencer, D. A. / Braun, R. D. / American Astronautical Society| American Institute of Aeronautics and Astronautics | British Library Conference Proceedings | 1996