Role of Simulation Assisted Risk Assessment in Abort Trigger Recommendations

摘要

A physics-based, simulation-assisted risk assessment of a crewed launch vehicle is used to evaluate the efficacy of failure detection mechanisms and response logic—known collectively as "abort triggers"— with respect to crew safety in the event of a vehicle failure during ascent to low earth orbit. Loss-of-crew risk is evaluated against three configurations of abort triggers, representing progressively broader and deeper sub-system coverage. An effort to propose new abort triggers beyond a limited baseline set is described. Given the rapidity and energy with which the most dangerous failures progress in launch systems, available warning time and failure mitigation effect are chief factors in determining an abort trigger's contribution to crew safety. Loss-of-crew effect is determined for the subset of proposed triggers for which warning time and failure mitigation data are available, while the upper bound on loss-of-crew reduction potential is determined through coverage analysis for all of the proposed triggers. The importance of the baseline set of abort triggers is also established, particularly for a "last resort" trigger that detects vehicle structural breakup. Finally, the considerations used in the final abort trigger selection are discussed.