Vision and Voyages for Planetary Science in the - Solar System ...

C
Cost and Technical Evaluation of Priority Missions
BACKGROUND
Concerns have been voiced for some time about the accuracy of the mission cost estimates used
in past decadal studies. A 2006 National Research Council (NRC) report concluded that “major missions
in space and Earth science are being executed at costs well in excess of the costs estimated at the time
when the missions were recommended in the National Research Council’s decadal surveys for their
disciplines. Consequently, the orderly planning process that has served the space and Earth science
communities well has been disrupted, and the balance among large, medium, and small missions has been
difficult to maintain.” 1 In response to this concern, the report recommended that “NASA should
undertake independent, systematic, and comprehensive evaluations of the cost-to-complete of each of its
space and Earth science missions that are under development, for the purpose of determining the
adequacy of budget and schedule.” 2
An extended discussion of cost estimates and technology readiness of candidate missions took
place during a subsequent NRC workshop concerning lessons learned from past decadal surveys.
Workshop participants found that cost and technology readiness evaluations that were conducted
independently of NASA estimates would add value to the surveys. They also suggested that uniform cost
estimating methods should be used within a given survey to facilitate cost comparisons among
initiatives. 3
With this guidance in hand, NASA called for an independent evaluation of cost and technology
readiness in the statements of task for the NRC assessment of the agency’s Beyond Einstein program. 4
Finally, in an act codifying the decadal surveys, Congress mandated that the NRC “include independent
estimates of the life cycle costs and technical readiness of missions assessed in the decadal survey
wherever possible. ”5 Therefore, the statements of task for the most recent astronomy decadal survey, 6 this
study (Appendix A), and the recently initiated heliophysics decadal survey all call for independent cost
and technical evaluations of recommended initiatives.
THE CHALLENGE OF COST, SCHEDULE, AND TECHNICAL ESTIMATES
The mission concepts used in decadal surveys are typically in preliminary stages of development.
In NASA parlance these are pre-Phase A concepts. Experience shows that the cost of a space mission is
usually not well understood until it has completed its preliminary design review (PDR). Even then,
unexpected mass, cost, and schedule growth can occur during the later phases of design and development.
Further challenging costing is the fact that some pre-Phase A concepts are more mature than others
because more resources have been devoted to their formulation. Accordingly, ensuring that a costing
exercise is level and fair requires that the relative maturity of concepts be taken into account.
Several different types of cost/schedule/technical risk evaluations are used when discussing
spacecraft missions. The best known are the so-called ICE (independent cost estimates) and NASA’s
TMC (technical, management, and cost). Less well known is the CATE (cost, schedule, and technical
evaluation). Each has its own strengths and weaknesses (Table C.1).
PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION
C-1