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

SUMMARY
Linked technical, cost, and schedule estimates were developed for each of the priority mission
concepts selected by the committee. The use of historical experience databases and evaluation of the
technical risk, cost, and schedule histories of analogous space systems which had already flown plus the
extensive interaction of technical, cost, and schedule experts with the proposing teams provide, in toto, a
high degree of confidence that the resulting assessments are realistic and credible.
The CATE process derived mission costs that are considerably higher than the cost estimates
provided by the design center study teams. The reason is that project-derived cost estimates are typically
done via a bottoms-up or “grass roots” approach, and beyond standard contingencies they do not include
probabilities of risk incurred by necessary redesigns, schedule slips, or launch vehicle growth. In other
words, these estimates typically do not account for the “unpleasant surprises” that historically happen in
nearly all space mission developments.
CATEs include a probabilistic assessment of required reserves assuming that the concept achieves
the mass and power as allocated or constrained by the respective stated project contingencies within the
schedule as stated by the project. In addition to these reserves, additional cost threats are also included
that quantify potential cost growth based on design maturity (mass and power growth) and schedule
growth. Potential cost threats for larger required launch vehicle capability are also included. It is the
combination of these reserves and cost threats that are often the main reason for the large differences
between the CATE appraisal and the project estimate. Differences in the estimates for hardware costs
(instruments and flight systems) can also be a contributing factor.
As noted in several places in this report, the planetary program has been plagued for many years
by use of cost estimates that in retrospect turn out to have been too optimistic. The result has been cost
overruns that can be highly disruptive to the program. The CATE process, which uses history as its guide,
has been designed, and used in this decadal survey, to prevent this problem.
REFERENCES
1. National Research Council, An Assessment of Balance in NASA’s Science Programs, The
National Academies Press, Washington, D.C., 2006, p. 3.
2. National Research Council, An Assessment of Balance in NASA’s Science Programs, The
National Academies Press, Washington, D.C., 2006, p. 3.
3. National Research Council, Decadal Science Strategy Surveys: Report of a Workshop, The
National Academies Press, Washington, D.C., 2007, pp. 21-30.
4. National Research Council, NASA’s Beyond Einstein Program: An Architecture for
Implementation, The National Academies Press, Washington, D.C., 2007, pp. 66-114.
5. Congress of the United States, National Aeronautics and Space Administration Authorization
Act of 2008, Public Law 110-422, Section 1104b, October 15, 2008.
6. National Research Council, New Worlds, New Horizons in Astronomy and Astrophysics, The
National Academies Press, Washington, D.C., 2010, Appendix C.
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PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION
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