The objective for the Phase II effort will be to develop a comprehensive, efficient, and flexible uncertainty quantification (UQ) framework implemented within a matured user-friendly software, which will enable the modeling of both inherent and epistemic uncertainties in spacecraft system models, have a general quantification of margins and uncertainties (QMU) capability for system certification and reliability assessment, and utilize advanced methods based on non-intrusive polynomial chaos (NIPC) for efficient and accurate propagation of mixed (inherent+epistemic) uncertainties as also demonstrated under the Phase I effort. In the proposed project, an adaptive uncertainty quantification methodology, which will successively utilize different NIPC methods depending on the size of the problem along with the non-linear global sensitivity information, will be implemented to address the computational expense of UQ in complex spacecraft system simulations with large number of uncertain variables. The developed UQ framework and QMU capability will be demonstrated on a large-scale spacecraft system model that is of interest to NASA. This proposed work will compliment M4 Engineering's expertise in developing simulation technologies that solve relevant demonstration applications. The researchers from MS&T (RI) will guide the implementation of UQ and QMU methodologies and contribute to the proposed effort with their UQ expertise in aerospace simulations.