Quantitative approach to independent schedule estimates of NASA Science Missions

This paper examines a multi-level quantitative schedule analysis and estimating approach similar to one that is used when evaluating proposal costs, and cost risks. The Aerospace Corporation has developed a process for performing independent schedule estimates (ISE), which utilizes an analogy-based schedule assessment methodology, permitting greater insight into mission development times. The authors have used this tool in many proposal evaluations and independent assessments when estimating planetary and earth-orbiting mission schedules. Specific examples of how this tool has been used to evaluate overall development time and interim development milestone plans will be presented. Additionally, data will be shown for a past application of this tool in evaluating the schedule risk of a mission, and how the data compares to schedule reserves guidelines. This paper illustrates the progression in schedule estimating, and the importance of equal treatment as a programmatic discipline on par with cost estimating.