Assessment of Mission Size Trade-offs for NASA's Earth and Space Science Missions addresses fundamental issues of mission architecture in the nation's scientific space program and responds to the FY99 Senate conference report, which requested that NASA commission a study to assess the strengths and weaknesses of small, medium, and large missions. This report evaluates 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; identifies which elements of the SSB and NASA science strategies will require medium or large missions to accomplish high-priority science objectives; and recommends general principles or criteria for evaluating the mix of mission sizes in Earth and space science programs. Assessment of Mission Size Trade-offs for NASA's Earth and Space Science Missions considers 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.
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Assessment of Mission Size Trade-offs for NASA's Earth and Space Science Missions
NATIONAL ACADEMIES PRESS
Copyright © 2000 National Academy of Sciences
All right reserved.
This report addresses fundamental issues of mission architecture in the nation's scientific space program and responds to the FY99 Senate conference report, which requested that NASA commission a study to assess the strengths and weaknesses of small, medium, and large missions. To that end, three tasks were set for the Ad Hoc Committee on the Assessment of Mission Size Trade-offs for Earth and Space Science Missions:
1. 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;
2. Identify which elements of the SSB and NASA science strategies will require medium or large missions to accomplish high-priority science objectives; and
3. Recommend general principles or criteria for evaluating the mix of mission sizes in 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 theresearch community, government-industry-university partnerships, graduate student training, and the like.
The committee approached these questions in light of the changing environment at NASA, which has been conducting an increasing number of smaller space and Earth science missions having shorter development times and using streamlined management methods, advanced technologies, and more compact platforms than had been employed in the past. The committee referred to this approach as the faster-better-cheaper (FBC) paradigm, a variant of "smaller, faster, cheaper, better" and similar phrases that have been used to describe the changing environment for space research missions.
The committee interpreted the FBC paradigm as a set of principles (including, but not limited to, streamlined management, flexibility, and technological capability) that are independent of the size or scope of a mission but can be matched appropriately to the science objectives and requirements for a given mission. It understood the term "mission" to mean the entire process of carrying out a space-based research activity, including scientific conception, spacecraft and instrument design and development, selection of development contractors, development costs, selection of launch capability, launch costs, mission operations, data analysis, and dissemination of scientific results.
It is within this broad context that the committee considered questions about the emerging FBC paradigm and its implications for mission size mixes in NASA's Earth and space science programs. How FBC is defined and how FBC principles are applied to programs of any scale have many implications for the space program: its tolerance for risk; its ability to carry out strategic plans; the scope, scale, and diversity of science investigated; the results and analytical products of its missions; the ways it trains young scientists and engineers; the role of international cooperation and the ease with which it can be incorporated into NASA's programs and plans; the role of universities, industry, government laboratories, and NASA centers in conducting space research missions; and the general health and vitality of the space science and Earth science enterprises. Policy makers looking for guidance on these programs in terms of cost and size trade-offs should be made aware that the variables are more numerous and much more complex than might at first be supposed.
The FBC approach emerged from the widely held belief that some large, traditional NASA missions had become unwieldy. With development times of over a decade (which often resulted in flying less capable technologies) and escalating costs, such missions came under increasing scrutiny, even given the magnificence of their promised (and realized) scientific returns. Traditional missions called into question the ability of NASA's Earth and space science research programs to obtain the highest quality and quantity of research return in the most timely and efficient fashion. Cuts in NASA's budget beginning in the early 1990s further encouraged new approaches for obtaining scientific returns in more efficient and cost-effective ways, albeit with added risk.
"Faster" missions can be made so by streamlining the management and development effort, by shortening the development schedule, by using the best available technology, and perhaps even by knowingly accepting more risk. In general, such methods will also lead to a "cheaper" mission. However, for NASA research programs, technological or managerial innovation are not ends unto themselves: the clear and obvious meaning of "better" is that more science-more knowledge and better quality and quantity of measurements-about some aspects of the universe around us is returned for a given investment and that such returns occur in a timely manner.
The impression that faster-better-cheaper also means "smaller" has raised concerns that there is a growing shift away from larger-scale endeavors in the Earth and space science programs. However, the tendency to equate FBC with the size or cost of a space or Earth science mission can overlook a number of things: the requirements unique to different disciplines, the complexities of scientific objectives, time and spatial scales, and techniques for implementing a mission. Total costs, mission capabilities, and the ultimate scientific results of space programs rely on a complex combination of the skill and performance of everyone associated with mission development, schedules, approaches to handling technical and management risks, technological implementation, and management style.
Through the careful planning processes that now characterize both the Earth science and the space science enterprises, the key outstanding questions of each discipline can be framed. Each such science question or disciplinary quest must then be examined in terms of the science community's priorities, the measurement requirements, and the technological readiness to determine which mission approach (or approaches) might be employed to address it. These science-based decisions on missions and approaches also incorporate strategies to engage and educate the general public and contribute to broader goals such as human exploration and development of space. A major consideration in all cases is the fiscal constraint that applies at any given time and the level of risk that can be tolerated by the mission's scientific priority and its role in NASA's strategic plan.
The ad hoc committee recognizes that the recent losses of missions conducted using the FBC approach-Lewis, the Wide-Field Infrared Explorer, Mars Climate Observer, and Mars Polar Lander-are in many ways calling into question some elements of the philosophy of FBC. Although it is beyond the scope of the committee's charge to assess individual mission failures (this is a task for the mission failure review boards), the committee calls attention to the potential implications of these losses for science and, especially, for the direction of the NASA Mars program. Is the Mars program committed to a technology path that is proving to be riskier than its proponents originally anticipated? Are recent losses turning the program toward sample return missions that lack the critical precursors recommended in science strategy reports? How seriously have the scientific rationale and robustness of the Mars program been affected by the information lost from recent mission failures? Do current and future mission programs have ample time and budgets to integrate the lessons learned from previous failures? These and other ramifications of the recent series of losses of missions implemented under the FBC paradigm are of pressing and paramount concern.
The committee supports several principles being implemented in the FBC methodology. Specifically, it found a number of positive aspects of the FBC approach, including the following:
A mixed portfolio of mission sizes is crucial in virtually all Earth and space science disciplines to accomplish the various research objectives. The FBC approach has produced useful improvements across the spectrum of programs regardless of absolute mission size or cost.
Shorter development cycles have enhanced scientific responsiveness, lowered costs, involved a larger community, and enabled the use of the best available technologies.
The increased frequency of missions has broadened research opportunities for the Earth and space sciences.
Scientific objectives can be met with greater flexibility by spreading a program over several missions.
Nonetheless, some problems exist in the practical application of the FBC approach, including the following:
The heavy emphasis on cost and schedule has too often compromised scientific outcomes (scope of mission, data return, and analysis of results).
Technology development is a cornerstone of the FBC approach for science missions but is often not aligned with science-based mission objectives.
The cost and schedule constraints for some missions may lead to choosing designs, management practices, and technologies that introduce additional risks.
The nation's launch infrastructure is limited in its ability to accommodate smaller spacecraft in a timely, reliable, and cost-effective way.
objectives. An emphasis on medium-size missions is currently precluding comprehensive payloads on planetary missions and has tended to discourage planning for large, extensive missions.
Ensure that science objectives-and their relative importance in a given discipline-are the primary determinants of what missions are carried out and their sizes, and ensure that mission planning responds to (1) the link between science priorities and science payload, (2) timeliness in meeting science objectives, and (3) risks associated with the mission.
Technology and Instrumentation
Technology development is a cornerstone of first-rate Earth and space science programs. Advanced technology for instruments and spacecraft systems and its timely infusion into space research missions are essential for carrying out almost all space missions in each of the disciplines, irrespective of mission size. The fundamental goal of technology infusion is to obtain the highest performance at the lowest cost.
The scientific program in Earth and space science missions conducted under the FBC approach has been critically dependent on instruments developed in the past. The ongoing development of new scientific instrumentation is essential for sustaining the FBC paradigm.
Maintain a vigorous technology program for the development of advanced spacecraft hardware that will enable a portfolio of missions of varying sizes and complexities.
Develop scientific instrumentation enabling a portfolio of mission sizes, ensuring that funding for such development efforts is augmented and appropriately balanced with space mission line budgets.
Access to Space
The high cost of access to space remains one of the principal impediments to using the best and most natural mix of small and large spacecraft. While smaller spacecraft might appear to be the right solution for addressing many scientific questions from orbit, present launch costs make them an unfavorable solution from an overall program budgetary standpoint. Moreover, larger missions, too, are plagued by the excessive costs per unit mass for present launch vehicles.
The national space transportation policy requiring all U.S. government payloads to be launched on vehicles manufactured in the United States prevents taking advantage of low-cost access to space on foreign launch vehicles.
Develop more affordable launch options for gaining access to space, including-possibly-foreign launch vehicles, so that a mixed portfolio of mission sizes becomes a viable approach.
International collaboration has proven to be a reliable and cost-effective means to enhance the scientific return from missions and broaden the portfolio of space missions. Nevertheless, it is sometimes considered, within NASA, to be detrimental, perhaps because it adds complexity and can bring delays to a mission. It is also perceived to give a mission an unfair advantage and, in part, to increase NASA's financial risk.
In the past, NASA had within its budgets an international payload line, which was an extremely useful device for funding the planning, proposal preparation, and development and integration of peer-reviewed science instruments selected to fly on foreign-led missions. This line offered the U.S. scientific community highly leveraged access to important new international missions by providing investigators with additional opportunities to fly instruments and retrieve data, especially during long hiatuses between U.S. missions in a given discipline.
Encourage international collaboration in all sizes and classes of missions, so that international missions will be able to fill key niches in NASA's space and Earth science programs. Specifically, restore separate e, peer-reviewed announcements of opportunity for enhancements to foreign-led space research missions.
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Table of ContentsContents
1 ISSUES AND CONSIDERATIONS IN THE ASSESSMENT OF MISSION SIZE TRADE-OFFS IN THE EARTH AND SPACE SCIENCES....................6
Fundamental Science Limits....................7
Measuring and Enhancing the Scientific Return on Investment....................14
Access to Space....................27
Problems with Past Missions....................28
2 SCIENCE PRIORITIES AND NASA MISSION PLANS....................31
Discipline-Specific Issues and Concerns....................38
3 SUMMARY AND RECOMMENDATIONS....................52
Strengths and Weaknesses of Small and Large Missions....................53
Recommendations in Response to the Charge....................54
Other Findings on Issues Affecting Mission Size Mix....................56
APPENDIXES A Letter of Request from NASA to the Space Studies Board....................61
B Statement of Task....................65
C Information Sought from Space Studies Board Discipline Committees....................67
D Meeting Agenda....................69
E Material Provided by Space Studies Board Discipline Committees....................71
F Acronyms and Abbreviations....................86
G Biographies of Committee Members....................90