Transition from the Global Positioning System (GPS) legacy control system to the new Operational Control Segment Architecture Evolution Plan (OCS/AEP) provides flexibility and growth to meet military and civil needs for the next 30 years. The control system provides command, control, and maintenance services to the GPS space segment. The transition's key event—Enhanced Phased Operations Transition—occurred on Sept. 14, 2007. Aerospace, the Air Force, and other mission partners were involved in a number of activities that took place before and after this major event, and their work is ongoing.
Mission assurance for the transition is composed of interrelated efforts by many different groups, including Aerospace, the 50th Space Wing at Schriever Air Force Base, the GPS Independent Review Team, and the GPS Wing—the DOD acquisition office for developing and producing GPS satellites, ground systems, and military user equipment. Aerospace's launch readiness review process is a model for the SMC chief engineer's Control System Independent Readiness Review Team, a component of mission assurance for the transition. The control system transition, however, occurred over a period of 5 days—rather than the seconds to minutes for a launch vehicle—and was supported continuously by satellite operators in the worldwide network of GPS monitoring stations.
Aerospace and the GPS Wing performed a comprehensive review of all mission assurance activities to make certain that the transition was transparent to the GPS user community. The purpose of the analysis was to ensure that the efforts are effective, adequate, and efficient. Specifically: Are there any gaps between the various mission assurance efforts and the disparate teams executing them? Are there any unnecessary duplications of effort? In cases where there are beneficial or necessary overlaps, are the participants taking advantage of the synergies between them?
To identify possible gaps or overlaps, the transition team examined all efforts related to mission assurance, with emphasis on software testing and on the transition from the legacy control system to OCS/AEP. The results were captured in a simple matrix format that revealed a few minor overlaps, now adjusted to streamline the processes and improve efficiency in the future. Initial findings have been briefed to the GPS Independent Review Team and senior military leadership in the GPS community.
—Michael Campbell, Chief Software Engineer