Cleared for launch — Lessons learned from the OSIRIS-REx system requirements verification program

Requirements verification of a large flight system is a challenge. This paper describes the approach to verification of the Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSlRlS-REx) system requirements. It also captures lessons learned along the way from the systems engineers embroiled in this process. This paper begins with an overview of the mission and science objectives as well as the project requirements verification program strategy. A description of the requirements flow down is presented including an implementation for managing the thousands of program and element level requirements and associated verification data. This paper discusses both successes and methods to improve the managing of these data across multiple organizational interfaces. The team's risk-based approach to verifying system requirements at multiple levels of assembly is presented using examples from work at instrument, spacecraft, and ground segment levels. A discussion of system end-to-end testing limitations and their impacts to the verification program is included. Finally, this paper describes lessons learned during the execution of the verification program across multiple government and commercial organizations. These lessons and perspectives can be valuable to all space systems engineers developing a large NASA space mission.