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An Initial Review of Microgravity Research in Support of Human Exploration and Development of Space 4 Programmatic Issues In the previous chapters of this report, an initial identification was made of the scientific and related technological issues facing NASA's HEDS endeavor. In looking specifically at mission enabling and enhancing technologies, the committee identified several scientific challenges that need to be addressed by the research community. It is clear that fundamental scientific questions in the physical and biological sciences need to be answered before many exploration technologies can be efficiently developed. MRD's major contribution to NASA is its support of fundamental research that examines the role of gravity in physical and biological systems, but there are steps that MRD can take to strengthen the contribution of that science to HEDS. Discussed below are several points of consideration and recommendations that the committee believes important to MRD's support of the HEDS enterprise. MRD should be prepared to stimulate and support critical microgravity research to help discriminate among competing HEDS technologies, specifically providing information so that NASA can make informed choices among them. MRD should, on a continuing basis, assist NASA in identifying critical technologies that would benefit future HEDS missions and then seek opportunities in microgravity research to contribute to their efficient realization. MRD should, however, remain both flexible and cautious in evaluating such opportunities. Major advances in technology can result from basic research undertaken without regard to current technological priorities, which have yet to be even identified. In addition, the timing of such technological advances is often unpredictable. The process of gathering and exchanging information relevant to deciding research selections that could support HEDS missions should be strengthened. Specialized workshops, cross-divisional teams, advisory panels, and study groups attended by mission technologists and microgravity scientists are among the suggested mechanisms to achieve this recommendation. Such

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activities would encourage the exchange of ideas between technologists and scientists, provide better communication and ongoing awareness of the technology needs for MRD, and also allow timely transfer of microgravity research findings to HEDS technologists. The goals of HEDS involve the development of complex technological systems that require, for example, the integration of knowledge from such apparently disparate fields as biotechnology, fluid physics, and materials science. Examples might include studies of biologically based systems and fluids management systems that could address life-support needs or the multiple disciplines required for in situ resource recovery. MRD may find it advantageous, where appropriate, to initiate a limited number of projects focusing on cross- disciplinary research topics, in order to develop experience in cross-disciplinary research selection and project management. Various scientific disciplines must be integrated in order to design and evaluate complex systems, and MRD could provide the necessary research methodologies for this purpose. While robust scaling laws involving the g level may be available for some microgravity disciplines, allowing predictions and extrapolations between microgravity and terrestrial g0, this usually does not hold true in more complex systems. Furthermore, for many phenomena and processes affected by gravity reduction, it is not yet known whether a threshold effect occurs at some g level. This remains particularly true, for example, in biological areas, where it is difficult to model multistep processes, which may include significant shifts in the relative importance of gravity. Recognizing that some of the missions envisioned by HEDS involve significant encounters with fractional g0 environments (lunar gravity = 0.16 g0, Martian gravity = 0.37 g0), MRD should consider giving more attention to studies conducted at fractional g0 where applicable to HEDS technologies. NASA's ongoing investments in automation and robotics are expected to benefit both human and robotic HEDS missions, both in space and in terrestrial and extraterrestrial settings. HEDS missions will often involve spacecraft operations that are sufficiently far from Earth to demand high levels of autonomous operations and control in part because of the unacceptably long time lags associated with speed-of-light communications. Improved automated and teleoperational capabilities can enhance the science and commercial return on NASA's investment, reducing operating costs and improving safety and comfort on space operations. MRD should carefully follow these efforts to make sure that microgravity issues, especially for robotics, receive appropriate research attention. It is expected that the ISS will provide a unique platform for conducting long-duration microgravity scientific research and assessing the efficiency and long-term suitability of many technical systems important to HEDS. In addition to its program of basic research aboard ISS, MRD should take advantage of the station and its subsystems for test bed studies of science concepts applicable to HEDS technologies. This could include, for instance, a role for applied