IXPE Observatory Verification and Validation Approach and Threads Tool

The Imaging X-ray Polarimetry Explorer (IXPE) is a NASA Small Explorer X-ray astrophysics mission being implemented by a geographically dispersed team. The IXPE collaboration and Observatory complexity provide both unique challenges and advantages for Project V&V. A rigorous and iterative V&V process is essential to ensuring the successful realization of reliable and cost effective IXPE Mission System. The IXPE verification, validation and characterization (V&V) process starts at the component/unit level and rolls up to appropriate higher levels. V&V compliance is assured by collaborative development by the V&V Team which spans all project organizations. The V&V process provides a framework, with appropriate confidence, to show that all needs and expectations are met by the as-built system. Proof is in the form of traceable detailed evidence of compliance at every level rolling up to and including the overall system and architecture levels. The detailed verification approach for IXPE components/units/subassemblies/subsystems is the responsibility of the applicable subsystem RE supported by systems and the I&T team. All verification processes, analyses and steps are documented. IXPE is using a V&V threads process which is ideal for use in showing compliance when a requirements set is dependent on a complex set of actions/processes. It's a system engineering graphics method to ensure all `contributors' and `influencers' are included. When applicable, verification threads are provided to support the verification compliance/sell-off process. This paper summarizes the IXPE mission and describes the verification, validation and characterization activities planned for the IXPE mission including the use of V&V threads.