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6 . . . . . . Discussion and Recommendations In the introduction to the m~crogravity portion (Part B) of this report, the task group sketched a possible long-term research program in physics and chemistry in a microgravity environment and tried to state its rationale. In the succeeding four chapters this program was illustrated with examples of experiments, some of which are now in various stages of development and others of which are envisioned for later during the period covered by this report. Much of the ongoing research in microgravity physics and chemistry is being funded by NASA's Physics and Chemistry Experiments in Space (PACE) program. PACE currently sup- ports about 15 experimental projects throughout the country. To date, none of these experiments have been flown. However, one of the experunents is about to fly, and flight hardware for others is beginning to be built. As the projects move from earth-bound preliminary experiments to full-flight experunents, the cost of each experiment increases by about one order of magnitude. Therefore, the natural maturation of the program now occurring places severe demands on program funds. Because of this, little effort is now being made to solicit new proposab. Until the funding of PACE and other basic-science microgravity programs is substantially in- creased, few if any new projects can be started. Even with funding available to bring these experiments to readiness for flight, the 90

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91 task group expects flight opportunities to be very restricted for the remainder of this decade. Although flight facilities for niicrogravity experiments are now limited, the task group expects this picture to be much brighter in the era of the Space Station. Space Station planning has been, and continues to be, very responsive to the needs of experunents in microgravity. For example, the evolution of the Power tower" concept of the Space Station to the "power arrow, and on to the stain keel" configuration has been driven largely by the needs of microgravity experiments. The Microgravity and Materials Pros ceming Module ~ another example of the unportance given to rn~crogravity in Space Station planning. The task group foresees an important symbiosis between mi- crogravity physics and chemistry and materials processing in space. These two programs wiD not only share facilities, they will share technology, much of which wait be developed during the next decade. For example, the task group expects the lines of re- search described in the preceding chapters to require more precise measurement and lower g levels from now until well into the next century. This development will place technical requirements on space systems that are difficult to predict in detail. However, it is very important for NASA to attempt these predictions now. It is equally important to plan detailed strategies for meeting these requirements and to do the necessary testing to predict the feasi- bility and merit of each strategy. This planning should be pursued vigorously now, because configurations of the large space systems that are to be ~ operation in the 1995 to 2015 time frame are now being determined. Decisions made now can preclude technical strategies that m~crogravity research in the twenty-first century will demand. Therefore, it is important to anticipate these strate- gies as accurately as possible. By way of example, consider the acceleration environments that may be present in the spacecraft on which future microgravity experunents will be earned out. By acceleration environment ~ meant both the steady state acceleration level, g, its orientation relative to the experimental apparatus, and the tune-dependent acceleration (~g-noise" or ~gjitter"~. At present, the task group is reasonably confident that the noise or jitter requirements can be met at all frequencies above ~ Hz by combinations of careful noise control and properly designed molation tables. The steady state acceleration requirements are not as easy to meet. Microgravity

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92 experunents that are now being developed for flight require lit- eral "microgravity.~ They assume gravity levels down to the 10-5 to 10-6 g range. Evolution of some of these experiments into the twenty-first century will call for Unknot gravity, i.e., 10~9 g and below. Technology development to meet these and other requirements of the microgravity and nanogravity experiments should be vigorously pursued. This task group believes that the m~crogravity environment offers opportunities for important scientific advances In the testing of fundamental theories and the Recovery of new phenomena and new states of matter. ~ particular: 1. Our ability to test fundamental concepts such as renormal- ization group theory can be greatly enhanced in the absence of gravity-induced nonuniformities. 2. Our understanding of nonlinear, nonequilibrium phenom- enafor example? fluid flow, condensation, soliclification, combus- tion, and a wide range of related dynamical processescan be significantly advanced by experunents under conditions where the underlying behavior Is not masked by the effects of gravity. 3. New static or dynamic states of matter that do not exist in normal gravity may be created and investigated. In order to take advantage of these opportunities, we must recognize certain unique features;of the m~crogravity program: its relevance to an extremely broad range of scientific activities and its resulting need for versatility and responsiveness in its operation. Specifically, the task group recommends that: I. NASA should increase its support for ground-based funda- mental research in areas for which m~crogravity experiments may be relevant. These resources are to be focused on isolating those aspects of complex problems that can be uniquely investigated in space. 2. NASA should significantly expand its support of one or more centers for microgravity research. These centers should be- come national facilities devoted both to the basic science and to the development of the specialized skins and technologies that are needed for the effective implementation of microgravity experi- ments. 3. The microgravity program should include strategies to at- tract outstanding scientists into the program with the expectation of research successes in a reasonable time frame.

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93 4. In scheduling flights, the basic m~crogravity experunents discussed above should be given the highest possible priority. In this way, the process of interplay between scientific discoveries and new commercial applications can proceed in a timely fashion.

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