Post ight analysis of the Mars Path nder hypersonic, continuum aerodynamic data base is presented. Measured data include accelerations along the body axis and axis normal directions. Comparisons of pre ight simulation and measurements show good agreement. The prediction of two static instabilities associated with movement o f the sonic line from the shoulder to the nose and back was con rmed by measured normal accelerations. Reconstruction of atmospheric density during entry has an uncertainty directly proportional to the uncertainty in the predicted axial coe cient. The sensitivity of the moment coe cient to freestream density, kinetic models and center-of-gravity location are examined to provide additional consistency checks of the simulation with ight data. The atmospheric density as derived from axial coe cient and measured axial accelerations falls within the range required for sonic line shift and static stability transition as independently determined from normal accelerations.

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This analysis pertains to the applicability of optima! sensitivity jnfcymatipn aerospace vehicle design. An o p timal sensitivity (OF post-optimality) analysis refers to c o a~~ putations perfprmd once the initial optimization prQblen\ is solved. m~se cqmpuwons may be used to characpriza the design space abaut tpe present solution and infer cbang.es in this solutjon as a result of constraint or parameter variations, witbout re.optinaizing the entire system. The present analysis demopsws that post-optimality infonnatioq generated throua fipt-prdqr computations can be used to accurately predict tbq effect of constraint and parapeter perturbations pn the optimal solution. This assessment is based on tbq qolutipq of gn airqaft design problem in which the post-opWity g s W t e s are shown to be within a few percent of tbe true e04utton over the practical range of constraint andpimmewr variations. Through solution of a reusable, single-s@ge-w+rkit, launch vehicle design problem, this optimal sqvsitivi{y information is also shown to imprave the efficiency of @q Qesign process, For a hierarc4ically decomposal problepn, this computational efficiency is realized by estiwtina @e main-problem objective gradient through optimal sep&ivity calculations, By reducine, need for fiqite @ffemntit$ion of a re-optimized subprobieql, a significant d e c r e w in the number of objective funptiQn evaluations requited tp rewh the optimal solution is obtaiwd.

The selection of the unique aeroshell shape for the Mars Microprobes is discussed. A description of its aerodynamics in hypersonic rarefied, hypersonic continuum, supersonic and transonic flow regimes is then presented. This description is based on Direct Simulation Monte Carlo analyses in the rarefled-flow regime, thermochemical nonequilibrium Computational Fluid Dynamics in the hypersonic regime, existing wind tunnel data in the supersonic and transonic regime, additional computational work in the transonic regime, and finally, ballistic range data. The aeroshell is shown to possess the correct combination of aerodynamic stability and drag to convert the probe's initial tumbling attitude and high velocity at atmospheric-interface into the desired surface-impact orientation and velocity.

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