Assessing the science robustness of the Europa clipper mission: Science sensitivity model

Existing characterization of Europa's environment is enabled by the Europa Clipper mission's successful predecessors: Pioneer, Voyager, Galileo, and most recently, Juno. These missions reveal high intensity energetic particle fluxes at Europa's orbit, requiring a multidimensional design challenge to ensure mission success (i.e. meeting L1 science requirements). Risk averse JPL Design Principles and the Europa Environment Requirement Document (ERD) dictate practices and policy, which if masterfully followed, are designed to protect Clipper from failure or degradation due to radiation. However, even if workmanship is flawless and no waivers are assessed, modeling errors, shielding uncertainty, and natural variation in the Europa environment are cause for residual concern. While failure and part degradation are of paramount concern, the occurrence of temporary outages, causing loss or degradation of science observations, is also a critical mission risk, left largely unmanaged by documents like the ERD. The referenced risk is monitored and assessed through a Project Systems Engineeringled mission robustness effort, which attempts balance the risk of science data loss with potential design cost and increased mission complexity required to mitigate such risk. The Science Sensitivity Model (SSM) was developed to assess mission/science robustness, with its primary goal being to ensure a high probability of achieving Level 1 (L1) science objectives. The understanding of L1 science objective achievement is folded back into the spacecraft, instrument, and mission system design requirements in an iterative fashion. The Science Sensitivity Model development is a cross-Project multidisciplinary effort leveraging, and literally linking, several novel Project products: Mission Science Traceability and Alignment Framework (M-STAF): framework for writing Level 2 (L2) science measurement requirements in an organized and cohesive manner such that a science requirement set is complete and consistent across the instruments [1]. Fault/Reliability Analysis: assesses the probability a recoverable failure occurs on the spacecraft or instrument and the time it takes for the Europa Clipper system to recover. Verification of Europa Requirements Integrating Tour and Science (VERITaS): model for assessing attainment of L2 science measurement requirements (as specified in M-STAF) for a given trajectory [2]. This tool is used to triage candidate Europa tours and to understand requirement sensitivity if the face of expected outages. Project Science Traceability and Alignment Framework (P-STAF): framework that builds upon the idea of the Science Traceability Matrix (STM) to link L2 science measurement requirements to L1 science measurement requirements, enabling the understanding of instrument dependencies and robustness [3]. This paper will tie these topics together and show how they interconnect to ensure Europa's science objectives are attained in the face of a challenge few deep space missions have encountered.