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Assessment of Mission Size Trade-offs for NASA’s Earth and Space Science Missions B Statement of Task BACKGROUND In the past several years there has been much emphasis in NASA on selecting, building, and launching “smaller, faster, cheaper, better” space missions. How NASA implements this new paradigm has ramifications for the relative roles of universities, industry, and NASA centers; opportunities for students to participate in experi-mental space research; modes of support for advanced technology development; ease of coordination in planning international cooperation; and other programmatic and institutional areas. Sometimes this emphasis creates the impression that NASA has completely abandoned the medium and larger missions it tended to emphasize in the past. Apparently in response to such concerns, Congress directed NASA to “contract with the NRC for a study across all space science and Earth science disciplines to identify missions that cannot be accomplished within the smaller, faster, cheaper, better regime. The [study] report should focus on the next 15 years, and attempt to quantify the level of funding per project that would be required to meet the specified scientific goals. The report also should identify any criteria and methods that could be used to measure whether the science accomplished using small satellites is better than that accomplished with larger, more complex spacecraft.”1 NASA’s smaller, faster, cheaper, better strategy involves efforts to streamline mission development cycles and costs, thereby increasing the number and frequency of flight missions and providing more opportunities for investigators to access spaceflight data. Such missions can be developed and launched in a few years, at a flight rate of more than 10 per year, and at costs of no more than a few hundred million dollars each. In contrast, missions such as Viking, Voyager, Galileo, the Hubble Space Telescope, and AXAF required decades to develop and budgets of up to $1 billion or so. On the other hand, small missions do incur certain scientific costs and risks—for example, when they require compromises in the breadth or depth of measurements that can be accomplished on a small spacecraft or when design practices or features require risk-taking to meet cost constraints. Furthermore, some scientific investigations simply cannot be performed on small spacecraft—for example, when a large telescope aperture is required to gather enough light to conduct the necessary observations. These considerations lead one to conclude that a strong program probably needs a mix of mission sizes. These can be thought of as a 1 U.S. Senate. 1998. Department of Veterans Affairs, Housing and Urban Development, and Independent Agencies Appropriations Bill, 1999, 105th Congress, 2nd Session, S. Report 105-216.
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Assessment of Mission Size Trade-offs for NASA’s Earth and Space Science Missions portfolio whose content is determined by many variables, including scientific priorities and yield, cost, frequency of flight, technology utilization, and technical risk. PLAN The Space Studies Board will draw on its own membership and that of its standing discipline committees to conduct an independent assessment of how mission size relates to the ability of planned or potential missions to address high-priority scientific goals in Earth and space science over the next 15 years. Mission sizes will be treated in three broad categories—small (total cost less than $150 million), medium, and large (total mission cost greater than $350 million). Recent science strategy reports from the Space Studies Board discipline committees2 and NASA’s space and Earth science strategic plans will be used to define science goals and priorities for the period. Specifically, the board will do the following: Evaluate the general strengths and weaknesses of small, medium, and large missions in terms of their potential scientific productivity, responsiveness to evolving opportunities, ability to take advantage of technological progress, and other factors that may be identified during the study; Identify which elements of the SSB and NASA science strategies will require medium or large missions to accomplish high-priority science objectives; and Recommend general principles or criteria for evaluating the mix of mission sizes in the Earth and space science programs. The factors to be considered will include not only scientific, technological, and cost trade-offs but also institutional and structural issues pertaining to the vigor of the research community, government-industry-university partnerships, graduate student training, and the like. SCHEDULE The Space Studies Board will begin work on this project at its June 1999 meeting, continue work during its September executive committee meeting, and conclude report preparation at its November meeting. The relevant standing committees of the board (Committee on Astronomy and Astrophysics, Committee on Planetary and Lunar Exploration, Committee on Solar and Space Physics, Committee on Earth Studies, Committee on International Space Programs) will provide input based on discussions at their regularly scheduled meetings over the period. The Space Studies Board will pay explicit attention to ensuring that participation from its committees draws on a mix of individuals who have knowledge of and experience with large, medium, and small space missions. The draft report will go to external review in December 1999 and will be released in February 2000. 2 Space Studies Board, National Research Council, An Integrated Strategy for the Planetary Sciences: 1995-2010, 1994; SSB, The Role of Small Missions in Planetary and Lunar Exploration, 1995; SSB, The Role of Small Satellites in NASA and NOAA Earth Observation Programs, 2000; SSB, A New Science Strategy for Space Astronomy and Astrophysics, 1997; SSB, A Science Strategy for Space Physics, 1995; SSB, Assessment of Recent Changes in the Explorer Program, 1996; SSB, Scientific Assessment of NASA’s SMEX-MIDEX Space Physics Mission Selections, 1997; SSB and Aeronautics and Space Engineering Board, Reducing the Cost of Space Science Research Missions, 1997.
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