Uncertainty quantification for destructive re-entry risk analysis: JAXA perspective

Abstract

In order to improve the accuracy of the expected casualty risk prediction for the destructive re-entry, the related uncertainty factors are identified and the uncertainty quantification approach are proposed. Based on our studies and experience, the identified dominant uncertainty factors are the model accuracy, the attitude stability mode, the shape complexity and shape change, and the initial conditions at the entry start and the break-up. High-fidelity numerical simulations play the important role to model complex multi-disciplinary physics and to cover the wide range of environmental conditions with small numbers of model validation data. The real shape and the deformation effects are initialy modeled by the high-fidelity numerical simulations and finally modeled by the reduced empirical physics-based models. Flight data acquisition also plays important the role to quantify the uncertainties of the attitude stability mode, the break-up altitude, and the temperature distributions and to validate the integrated risk analysis model. Some of the key findings obtained by the high-fidelity simulation are discussed. It is also shown that various types parameter dependencies such as Mach number, wall temperature, surface curvature, and the effect of the turbulent flows on the aerodynamic characteristics and the heat flux distributions should be considered in the empirical models.