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8 Research Priorities INTRODUCTION In previous chapters of the report the committee discusses the past impact of gravity-related re- search in each of the disciplines that have been traditionally supported by the Physical Sciences Division (PSD) and recommends future research important to each of those disciplines. It also reviews emerging areas of research in fields such as nanomaterials, in which the PSD is now beginning to invest. In this chapter the committee summarizes the findings of previous chapters to provide guidance to the PSD in setting priorities across the microgravity disciplines, summarizes the recommendations for research in emerging areas, and makes recommendations on overall program directions. In order to assess and compare research across the microgravity disciplines, the committee critically examined the potential impact of the given research on the scientific field of which it is part, on NASA's technology needs, and on industry or other terrestrial applications. The committee's evaluation of the research in each of these categories is expected to assist NASA program planners by providing insight into the likely risks and potential rewards of the research that would be needed to create a vibrant microgravity research program that impacts all of these areas. Because most of the fields of research discussed in Chapter 7 have a brief history and are developing very rapidly, it was not possible to evaluate them using the same criteria used for the research in combustion science, fluid physics, fundamental physics, and materials science. (As indicated in Chapter 6, research in the biotechnology areas of tissue culturing and protein crystal growth was recently reviewed by the NRC and was not included in this evaluation at the request of NASA.) While the likelihood that PSD-funded research in emerging areas will result in significant impacts on NASA capabilities cannot be evaluated at this time, the magnitude of the impact of successful research is potentially very high. Accordingly, the committee prioritized the research topics in emerging areas only relative to one another and suggests that the PSD utilize the list of high-priority areas given below to help make allocations within the share of program funds set aside for these emerging areas. 83

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84 ASSESSMENT OF DIRECTIONS IN MICROGRAVITY AND PHYSICAL SCIENCES RESEARCH AT NASA RESEARCH PRIORITIES IN EMERGING AREAS In the committee's phase I report (NRC, 2001), it was recommended that the PSD should focus its research in emerging areas on topics that meet the following criteria: 1. Directly address scientific challenges at the interfaces between the physical sciences, engineer- ing, and biology in support of NASA's mission, preferentially capitalizing on existing expertise or infrastructure in the Physical Sciences Division, and 2. Support research either not typically funded by other agencies or to be conducted in close partnership with other agencies. While many areas in nanotechnology research are already highly supported by other agencies and other divisions within NASA, the PSD does have an opportunity to focus work on a select number of topics that can meet these criteria. Research in these emerging areas has the potential to provide powerful new tools and approaches that will greatly benefit NASA's capabilities. In addition, the considerable potential of the microgravity research disciplines to yield important and even paradigm- shifting results (as discussed in the next section) argues for a balanced program of research in the PSD that retains the unique potential for studying gravitational effects on phenomena in combustion, fluids, materials, fundamental physics, and biotechnology topics such as tissue culturing. For these reasons, the committee concluded that the fraction of the physical sciences program devoted to the recommended research in emerging areas should remain relatively modest, perhaps 15 percent of the ground-based program, until such time as a clear justification arises for increasing its size based on the criteria above as well as the ability of research in emerging areas to compete with existing programs. This fraction, which would bring the emerging research program into parity with the other major areas of research funded by the PSD, will allow NASA to have an impact on a limited number of highly focused topics within the broad purview of emerging areas while leveraging the research of other agencies. It also permits the majority of the research in the microgravity areas to continue to produce the high-impact results described in previous chapters. In addition, the amount of research currently funded in the emerging areas should increase gradually toward this fraction, which will allow the quality of the investigations chosen for funding to remain as high as possible. Because NASA is likely to have a need for unique applications of nanotechnology, the PSD should develop a level of research expertise in these fields that will allow it to effectively evaluate and apply new advances in its own programs. In order to do so it will be particularly important to develop strong programs and connections with the leaders in these fields. Whenever possible, the PSD should seek to apply the findings of other agencies to topics that could directly benefit technologies of unique interest to NASA. It should be noted that some of the research discussed in Chapter 7 does look at gravitational effects, and these may be areas into which some research in microgravity combustion, fluid physics, fundamen- tal physics, materials science, or biotechnology research could naturally evolve. Examples might be certain types of nanomaterials research in the microgravity materials program or gravitational effects on subcellular assemblies in the biotechnology program. The recommendation regarding the proportion of emerging areas research in the PSD is not meant to restrict such eventual evolution of existing microgravity areas. However, such research must be competitive with other areas of research in the discipline and should be funded only if it is deemed to be a high priority on the basis of the rigorous selection criteria outlined in the discipline chapters and in the next section. Within the proportion of the program devoted to the emerging areas, the committee has recom- mended several of the topics discussed in Chapter 7 that appear to be particularly promising based on

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RESEARCH PRIORITIES 85 their potential to help address NASA technology needs and the ability of the PSD to make a unique contribution of knowledge or expertise. All of the areas recommended below satisfy the criteria identified in the phase I report for choosing research in the emerging areas. The development of methods for the long-term stabilization of proteins in vitro and research on cellular responses to gravity- mediated tissue stresses are of higher priority than the other areas, because they are not typically supported by other agencies. The research on exploiting nanotechnology for power generation and energy conversion is also ranked "most important" because of the great importance of power generation and energy conversion in NASA's spaceflight program, and the major impact these technologies may have on this program. The remaining areas (ranked "important") are heavily supported by agencies such as the Defense Advanced Research Projects Agency, the Department of Energy, the National Science Foundation, and the Department of Defense as well as by other divisions within NASA. Thus for the PSD to pursue research in these areas it must partner with these agencies or with other divisions within NASA. (The PSD has successfully partnered with other agencies in the past, such as the National Cancer Institute.) These recommendations are summarized below, and the reader is referred to the relevant sections of Chapter 7 for a more detailed discussion of their significance to NASA. Note that the topics are not rank-ordered within the priority categories. Most Important Develop methods for long-term stabilization of proteins in vitro (pp. 72-74~. Work on understanding cellular responses to gravity-mediated tissue stresses (pp. 76-77~. Exploit nanotechnology for power generation and energy conversion (pp. 67-68 and pp. 69-70~. Important Develop enabling technologies to produce nanoengineered hybrid materials with multiple func- tions (pp. 66-67~. Develop integrated nanodevices (pp. 71-72~. Study the stabilization of cellular function in vitro (pp. 74-76~. MICROGRAVITY RESEARCH PRIORITIES In assessing the promise of a microgravity research area, it was first necessary to look at the impact of the research on the field of which it is a part and the quality of the investigators in the program, since the impact of the past research provides insight into the ability of the program to select important research topics to fund and the quality of investigators in the program strongly affects the likelihood that future research will yield important results. As is shown in Chapters 2 through 5, NASA-supported investigations in combustion, fluid physics, materials science, and fundamental physics have had a major impact on these fields thus the PSD has been successful in funding high-impact research. Moreover, as NASA has successfully attracted a cadre of distinguished investigators as well as promis- ing young investigators in these areas, there is a very good probability that high-quality research will emerge from these communities in the future. Chapters 2 through 5 contain suggestions for future research directions in the microgravity disci- plines, and only the areas considered to be of high priority within those disciplines are recommended in the chapters. It should be kept in mind that there are many additional areas of promising research in

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86 ASSESSMENT OF DIRECTIONS IN MICROGRAVITY AND PHYSICAL SCIENCES RESEARCH AT NASA Most Important IL o ~ O z ~ Important 2b12~ ~ 13 1 \ ~ / 2a 3c 18 ( 14C ~ 1 ~ 15 10 3a Low PROBABILITY OF ACHIEVING IMPACT High FIGURE 8.1 Assessment of research topics in terms of their likely impact on scientific knowledge and under- standing. Most Important IL o t ~ z Important , ~ ~ 2b 1 ~ 3a 4b 1 18 ) Jet ' Low PROBABILITY OF ACHIEVING IMPACT High FIGURE 8.2 Assessment of research topics in terms of their likely impact on terrestrial applications such as industry's technology needs.

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RESEARCH PRIORITIES Critical Most Important IL o ~ O _ ~ F ~ Z ~ Important ~ 4b $~ 0- ~ 2b I ~ 3a Low PROBABILITY OF High ACHIEVING IMPACT ) FIGURE 8.3 Assessment of research topics in terms of their likely impact on NASA's technology needs. 87 Figures 8.1, 8.2, and 8.3: Only subjects already considered by the committee to be of high priority in at least one discipline are included in this analysis, and therefore the magnitude scale ranges only from important to very important (or critical). A subject may not have a high impact in every category and therefore may not appear in every figure. Numbers inside the same circle should be considered to occupy approximately the same position in the figure. The numbers in the figures represent the research topics as follows: 1. Multiphase flow and heat transfer; 2. Complex fluids: (a) self-assembly and crystallization, (b) complex fluid theologies; 3. Interfacial processes: (a) wetting and spreading, (b) capillary-driven flows and equilibria, (c) coalescence and aggregation (liquid phase); 4. Biofluid dynamics: (a) cellular biotechnology, (b) physiological flows; 5. Turbulent combustion; 6. Chemical kinetics; 7. Soot and radiation; 8. Smoldering combustion; 9. 10. Development of computer simulations of fire dynamics on spacecraft; Oxygen systems fire safety; 11. Ignition, flame spread, and screening techniques for engineering materials; 12. Antimatter search/measurements; 13. Elemental composition survey; 14. Complete the current set of fundamental physics ISS experiments: (a) low-temperature experiments, (b) relativity and precision clock experiments, (c) other NASA clock application experiments; 15. Nucleation process within, and the properties of, undercoated liquids; 16. Dynamics of microstructural development during solidification; 17. Morphological evolution of multiphase systems; 18. Computational materials science; 19. Collection of thermophysical data of liquid state in microgravity.

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88 ASSESSMENT OF DIRECTIONS IN MICROGRAVITY AND PHYSICAL SCIENCES RESEARCH AT NASA each of those disciplines that were not given the highest priority at this time and thus were not explicitly recommended. Some of these areas might rise to a higher priority in the future. In addition, the committee expects that in future years the communities will generate new research topics whose prom- ise will equal that of the topics recommended here. In this chapter, however, the committee limits its assessment to those areas described in the earlier chapters as currently being of high priority. Those recommended areas are as follows: Multiphase flow and heat transfer Complex fluids Self-assembly and crystallization Complex fluid theologies Interfacial processes Wetting and spreading Capillary-driven flows and equilibria Coalescence and aggregation (liquid phase) Biofluid dynamics Cellular biotechnology Physiological flows Turbulent combustion Chemical kinetics Soot and radiation Smoldering combustion Development of computer simulations of fire dynamics on spacecraft Oxygen systems fire safety Ignition, flame spread, and screening techniques for engineering materials Antimatter search/measurements Elemental composition survey Complete the current set of ISS experiments in fundamental physics Low-temperature experiments Relativity and precision clock experiments Other NASA clock application experiments Nucleation process within, and the properties of, undercooled liquids Dynamics of microstructural development during solidification Morphological evolution of multiphase systems Computational materials science Collection of thermophysical data of liquid state in microgravity. To evaluate these recommended research areas across disciplines, the committee separately judged the likelihood that the research would have a significant impact in each of three categories: (1) the scientific field of which it is part, (2) industry or other terrestrial applications, and (3 ~ NASA technology needs. Within each of these categories the committee specifically looked at both the magnitude of the potential impact that the research could have on its category, and the likelihood that the research would be successful in achieving that impact. The impact and likelihood of success were assessed indepen- dently of each other since it was possible for areas with a potential for high impact to have a low probability of success and vice versa. The results of the committee' s assessment are shown in Figures 8. 1, 8.2, and 8.3 (see pp. 86-87 ), which plot the magnitude of the impact that research on the topic could

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RESEARCH PRIORITIES 89 have in a given category, against the probability that the impact will be achieved. Note that the justification for the magnitude of the expected impact is given in the discipline chapters and is not discussed further here. It should be kept in mind that the setting of actual research priorities must depend on NASA programmatic goals, and those goals determine both the desired end result, such as scientific discovery, and the level of acceptable risk. The purpose of these plots is to provide NASA with the tools to rationally select the best research, regardless of which combination of scientific discovery (Figure 8.1), Earth applications (Figure 8.2), or NASA technology needs (Figure 8.3) NASA chooses to emphasize or what trade-offs between research risk and reward it is willing to accept. PEER REVIEW The committee has commented numerous times in past studies on the role that rigorous peer review has had in greatly improving the quality of the research funded by the Physical Sciences Division, and it strongly recommended the continued use of peer review in future funding selections (NRC, 1994, 1997, 2000~. As the program moves into new areas of research it is worth emphasizing again that any research proposal submitted to the program no matter how relevant to an area considered highly desirable for inclusion in the program should only be funded if it has undergone a rigorous peer review and has received both high marks for scientific merit and a high ranking compared to competing proposals. REFERENCES National Research Council (NRC). 1994. "On Life and Microgravity Sciences and the Space Station Program," letter from SSB Chair Louis J. Lanzerotti, Committee on Space Biology and Medicine Chair Fred W. Turek, and Committee on Microgravity Research Chair William A. Sirignano to NASA Administrator Daniel S. Goldin (February 25~. Space Studies Board, National Research Council, Washington, D.C. National Research Council, Space Studies Board. 1997. An Initial Review of Microgravity Research in Support of Human Exploration and Development of Space. National Academy Press, Washington, D.C. National Research Council, Space Studies Board. 2000. Microgravity Research in Support of Technologies for the Human Exploration and Development of Space and Planetary Bodies. National Academy Press, Washington, D.C.

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