All of the costs discussed in this report are presented in current-year (2008) dollars, not accounting for potential inflation that could occur between now and the decade in which these missions might be pursued. In general, preliminary cost estimates for proposed missions are, for many reasons, significantly lower than the final costs. Given the large cost estimates for many of the missions assessed in this report, the potentially large impacts on NASA’s budget by many of these missions are readily apparent.


The committee evaluated a total of 17 mission concepts for future space science missions (11 were “Vision Missions” studied at the initiation of NASA between 2004 and 2006; the remaining 6 were submitted to the committee in response to its request for information).2 The committee based its initial evaluation of each mission concept on two criteria: (1) whether the concept offered the potential for a significant scientific advance and (2) whether or not the concept would benefit from the Constellation System. The committee determined that all of the concepts offered the possibility of a significant scientific advance, but it cautions that such an evaluation ultimately must be made by the NRC’s decadal survey process referred to above. This report’s evaluations should not be considered to be an endorsement of the scientific merit of these proposals, which must of course be evaluated relative to other proposals.

The committee determined that 12 of the 17 mission concepts would benefit from the Constellation System, whereas 5 would not. See Table S.1 for a summary of the mission concepts, including their cost estimates, technical maturity, and reasons why they might benefit from the Constellation System.

The five mission concepts that the committee deemed not worthy of further study as Constellation missions according to its evaluation criteria simply do not require, or do not appear to benefit highly from, use of the Constellation System (see Table S.1). In several cases they should easily fit within existing launch vehicles. In one -EUSO (Extreme Universe Space Observatory), the committee questions the cost-effectiveness of a flagship-class space mission as compared with the expansion of existing ground-based facilities.

Notably, the committee did not receive any proposals in the Earth sciences. The committee lacked sufficient data to determine why it did not receive any such proposals, although it notes that the Vision Mission effort that sponsored many of the mission concepts evaluated in this study did not include Earth science, which at the time was separated organizationally within NASA from space science. It is possible that, if invited to consider the matter, the Earth science community may find uses for Constellation that are not readily apparent.

Finding: The committee did not receive any Earth science proposals and found it impossible to assess the potential of the Constellation System to meet the future needs of Earth-oriented missions.

The mission concepts reviewed during this study lacked the level of detail necessary for a full evaluation. In particular, the cost estimates were extremely rough. The lack of Earth science concepts also concerned the committee. NASA is still in the early stages of identifying the potential benefits of the Constellation System to the space science program and has not made a dedicated effort to evaluate the potential of the Constellation System for space and Earth science missions. As a result, the committee determined that the agency needs to continue efforts to attract and advance ideas for space and Earth science missions in general, and should develop a method for soliciting potential mission concepts.

Recommendation: NASA should solicit further mission concepts that are most likely to benefit from the capabilities of the Constellation System in each of the space and Earth science disciplines: astronomy and astrophysics, Earth science, heliophysics, and planetary science. The agency should seek mission concepts that are studied in a uniform manner with regard to design, system engineering, and costing.


In its interim report, the committee selected 7 of the 11 Vision Mission concepts as “worthy of further study as a Constellation mission.” See National Research Council, Science Opportunities Enabled by NASA’s Constellation System: Interim Report, The National Academies Press, Washington, D.C., 2008.

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