This paper provides a description of how the CGI requirements flow from the top of the overall WFIRST mission structure through the Level 2 requirements, where the focus here is on capturing the detailed context and rationales for the CGI Level 2 requirements. The WFIRST requirements flow starts with the top Program Level Requirements Appendix (PLRA), which contains both high-level mission objectives as well as the CGI-specific baseline technical and data requirements (BTR and BDR, respectively). Captured in the WFIRST Mission Requirements Document (MRD), the Level 2 CGI requirements flow from the PLRA objectives, BTRs, and BDRs. There are five CGI objectives in the WFIRST PLRA, which motivate the four baseline technical/data requirements. There are nine CGI level 2 (L2) requirements presented in this work, which have been developed and validated using predictions from increasingly refined observatory and instrument performance models.
We also present the process and collaborative tools used in the L2 requirements development and management, including the collection and organization of science inputs, an open-source approach to managing the requirements database, and automating documentation. The tools created for the CGI L2 requirements have the potential to improve the design and planning of other projects, streamlining requirement management and maintenance.
The WFIRST CGI passed its System Requirements Review (SRR) and System Design Review (SDR) in May 2018. The SRR examines the functional requirements and performance requirements defined for the system and the preliminary program or project plan and ensures that the requirements and the selected concept will satisfy the mission, and the SDR examines the proposed system architecture and design and the flow down to all functional elements of the system