Understanding the Drivers of Cost and Staffing Growth in Operating Earth-orbiting Science Missions

摘要

Significant effort and expense is devoted to the design, development, and launch of science missions. In the process, organizations executing and managing these missions may focus less attention on planning for Phase E (i.e., crafting estimates for mission operations, data analysis, and science). Separately, as found in this study and in an earlier study of Phase E cost growth for planetary missions, projects commonly use engineering build-up (i.e., "grass roots") as the methodology to estimate Phase E cost and staffing profiles. In the course of the mission, projects do experience cost and schedule threats that were not anticipated in the development of their "grass roots" estimates. As a result, some projects experience excursions from their original estimates prior to the end of the primary mission. By reviewing the project histories of various missions, one can identify the events and situations that have likely led to those budget excursions. This paper details the study of Earth-orbiting missions across three offices of the NASA Science Missions Directorate: Astrophysics, Earth Sciences, and Heliophysics. The study's objective is to expand knowledge of and to better understand the reasons for cost and staffing growth in Phase E. In this paper, the method, approach, and major findings are summarized as the Phase E Explanation of Changes (EoC). Some major steps in the study approach included: the review of project materials for Phase E budgets and staffing profiles; examination of major project reviews (e.g., Concept Study Report, Preliminary and Critical Design Reviews, re-plan packages); and interviews with project and operations management. From this work, narratives were compiled for each mission addressing the main drivers of cost and staffing growth in Phase E. The paper concludes with a set of observations and some suggestions and recommendations for operations planning and budgeting. This work is research that leverages and builds on findings from an earlier study of Phase E cost and staffing growth for planetary missions.