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Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
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Executive Summary

The microgravity environment (10-6g) of space provides a unique opportunity to further our understanding of various materials phenomena involving the molten, fluidic, and gaseous states by reducing or eliminating buoyancy-driven convection effects. The space environment also permits containerless processing, thus eliminating impurities and stresses introduced by contact with container walls. The anticipated scientific results of microgravity materials-science research range from establishing baselines for fundamental materials processes to generating results of more direct commercial significance. The specific objectives of the microgravity materials-science program of the Microgravity Research Division (MRD) of the National Aeronautics and Space Administration (NASA) include:

  • advancing our knowledge base for all classes of materials
  • designing and facilitating the executive of microgravity experiments that will help achieve this goal
  • determining road maps for future microgravity studies
  • contributing to NASA's Human Exploration and Development of Space enterprise
  • contributing to the national economy by developing enabling technologies of value to the U.S. private sector

The Space Station Furnace Facility (SSFF) Core was conceived to provide the mechanical, power, and control infrastructure for an array of experiment modules (EMs) in which a wide range of high-temperature, microgravity, materials-science experiments could be conducted on the future International Space Station (ISS). The SSFF Core was specifically designed for crystal growth and solidification research in the fields of electronic and photonic materials, metals and alloys, and

Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
×

glasses and ceramics in order to permit the experimental determination of the role of gravitational forces in solidification, crystallization, and thermophysical property measurement. The common infrastructure of the SSFF Core is intended to (1) reduce experiment implementation times by providing major generic subsystems that have long lead times; (2) reduce the up-mass and down-mass required for materials-science investigations; (3) provide flexibility in responding to evolving priorities of the materials-science research community; (4) reduce costs by eliminating the development, fabrication, and verification of redundant hardware and software systems; (5) reduce costs by providing common ground-support equipment, laboratory hardware, and operations support; and (6) facilitate the integration of new experiments. The EMs will contain the actual hardware (e.g., furnaces, samples, thermocouples) in which the experiments will be conducted. Whereas the SSFF Core is being developed and constructed by NASA, the EMs will be separately developed by the Principal Investigators in conjunction with independent equipment manufacturers.

Although the deployment of the SSFF Core was originally scheduled for June 1999, it was delayed until November 2002 because of revisions in the construction schedule of the ISS. NASA is attempting to capitalize on this delay by reviewing the current SSFF Core project in terms of the specific research capabilities afforded by the facility, the technology being developed and its usefulness to the U.S. materials-science community, and the procedures for selecting the research projects to be conducted in the facility.

To facilitate its review, NASA requested that the National Research Council conduct a study to (1) examine NASA's research plan for high-temperature, microgravity materials science; (2) assess the ability of the current SSFF Core concept to support the range of high-temperature experiments and associated specialized furnaces; (3) evaluate the usefulness of the planned high-temperature microgravity materials-science projects and developed technologies to the research and industrial materials-science communities in terms of already identified needs and planned activities through the year 2010;1 (4) assess the ability of NASA's high-temperature microgravity materials-science plan to accommodate evolving interests and priorities in the field of

1  

 The committee took the 13 projects that NASA has already selected as candidate investigations for the ISS as a representative sample of the research investigations that will be conducted throughout the lifetime of the SSFF Core.

Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
×

materials science; and (5) examine the procedures used by NASA to select experiments for the ISS and determine if they encourage active participation by the broader materials-science research community.

The Committee on Materials Science Research on the International Space Station was convened under the auspices of the National Materials Advisory Board to conduct this study and write this report. Because of the limited time allotted the study, the committee worked on the assumption that NASA's microgravity materials research program would continue unabated into the foreseeable future. The committee therefore focused on the fundamental aspects of the project: the ability and flexibility of the current SSFF Core concept and NASA's selection procedures for identifying and supporting research within the expansive and evolving field of materials science and engineering. No effort was made to evaluate current or previous research projects.

Meaningful research within the SSFF Core will only be possible if a quality microgravity environment can be successfully maintained. To maintain microgravity conditions, the instrument racks (IRs) for the Core will be isolated from the transient and oscillatory accelerations (termed ''g-jitter'') of the ISS via the active rack isolation system (ARIS), which is currently being developed by Boeing. ARIS is designed to compensate for vibratory accelerations between 0.01 and 300 Hz. The performance of ARIS will be compromised if vibratory accelerations are outside the specified range (e.g., if a rack is accidentally jarred) or if IR operation exceeds maximum allowed payload disturbance levels. In order to minimize the vibration levels controlled by ARIS and ensure that g-jitter levels remain within IR specifications, NASA has also stipulated that all cables and hoses for the IRs must have minimal stiffness. The umbilicals are still being developed, and a recent space shuttle flight test of ARIS was not successful.

Finding. Meaningful research in the SSFF Core will be impossible if a microgravity environment cannot be successfully maintained. The success of the SSFF Core therefore depends on the perfection of ARIS or the development of an alternative system for controlling g-jitter.

Nasa's Microgravity Research Program

The research areas originally identified by the MRD included the following classes of materials: electronic and photonic materials,

Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
×

glasses and ceramics, metals and alloys, and polymers and nonlinear optical materials. The MRD subsequently formed an 11-member Materials Science Discipline Working Group (DWG), primarily to review the science priorities, implementation plan, and long-term strategy of the materials-science program. The primary mechanism for soliciting broader input into the MRD materials-science program and for informing the community of the current program content and future research opportunities has been through biannual Microgravity Materials Science conferences. Two conferences organized by the DWG and hosted by the Marshall Space Flight Center in 1994 and 1996 (NASA 1996) were attended by approximately 300 to 350 scientists. Additional information was provided by two National Research Council reports: Towards a Microgravity Research Strategy (NRC, 1992) and Microgravity Research Opportunities for the 1990s (NRC, 1995).2 Based on the conferences and reports, the DWG identified fundamental physical and chemical phenomena research areas that it believed would benefit from long-duration microgravity conditions. Promising subjects for investigation included:

  • nucleation and metastable states
  • prediction and control of microstructure, pattern formation, and morphological stability
  • phase separation and interfacial phenomena
  • transport phenomena
  • crystal growth, defect generation, and control
  • extraterrestrial processes and technology development (e.g., welding in a vacuum and exploiting extraterrestrial materials for fuel, etc.)

Nasa's Microgravity Research Solicitation and Selection Processes

For NASA's microgravity materials-science research program to conduct basic and applied research that expands our knowledge base of materials behavior, the research program must be able to stimulate

2  

 NASA also supports some in-house research through the University Space Research Association, but these activities follow a separate funding process and were not reviewed by the current committee.

Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
×

and identify research proposals of the highest caliber. Thus, the inventory of materials-science experiments in the microgravity research program ultimately depends on the success of the proposal solicitation and selection processes.

In the committee's opinion, the 1996 NASA Research Announcement (NRA) soliciting proposals is well conceived and thoroughly describes the research areas and the ground-based and flight-based facilities. The solicitation also encourages and targets undergraduate participation in the microgravity research enterprise. The sections of the NRA concerning the current SSFF Core concept are not of the same high quality, however. Whereas the descriptions of the ground-based facilities provide researchers with sufficient descriptions and parameters for reduced gravity environments, the section on the current SSFF Core concept does not provide an adequate description of its flexibility. Even the name of the SSFF Core suggests that it is suitable only for high-temperature experiments. Although the committee recognizes that the SSFF Core is still in the concept and development stage, the key issue is whether the baseline facilities are sufficiently flexible to support a broad range of research opportunities.

Recommendation. NASA should provide more information in future NRAs on the flexibility and usefulness of the current SSFF Core concept. NASA should also consider changing the name of the SSFF Core to the Space Station Materials Research Facility or some other more inclusive title that would give researchers more insight into its scientific objectives and experimental flexibility.

The evaluation and selection process is also effectively conceived and designed. A strong feature of the process is that it includes extensive external peer review by scientists with and without microgravity materials-science research experience. Another proven evaluation strategy that is incorporated in the present external peer-review process is the grouping of proposals according to common themes, which facilitates comparative evaluations.

The factors used to evaluate priorities during the Initial Proposal Review segment of the selection procedure, which leads to initial funding decisions, are related to scientific merit. Although researchers must explain their need for a microgravity environment—preferably in quantitative terms—they are not required to argue the ultimate viability of their projects as flight experiments. Thus, decisions are not

Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
×

based on perceptions of present or future hardware capabilities, which is critically important both for ensuring opportunities for investigators who may not be knowledgeable initially about the details of flight systems and operations and for ensuring that hardware-based biases do not inadvertently work against scientific experiments with high intrinsic merit.

Finding. System design should not be the criterion that defines program opportunities. The programs selected for flight must be those that benefit science, engineering, and technology, and thus society, most significantly.

Recommendation. NASA should continue to ensure that perceived flight viability (i.e., current and projected hardware capabilities) does not influence the Initial Proposal Review segment of their selection process.

In the committee's opinion, a potential weakness in the current NASA review process is that the same panel is used during two different phases. During the second phase of the review process (i.e., the Science Concept Review phase), a panel is convened to recommend whether projects merit further ground-based research in preparation for potential flight experimentation. During a portion of the third phase (i.e., the Requirements Definition Review phase), the same experts are reconvened to conduct the Science Review and recommend whether projects merit hardware design and development in preparation for flight experimentation. Although the committee acknowledges that continuity and familiarity with research projects are important, NASA must ensure that reviewer ownership and advocacy do not compromise the evaluation process. One way to do this is to use only a fraction (e.g., less than half) of the Science Concept Review panel members in the later Science Review.

One indication of the success of a solicitation and selection process is by the scientific balance of the inventory of research experiments that are chosen. Although the first priority must always be scientific merit, a concentration of proposals in a subset of research areas could indicate that the solicitation process is not reaching the entire community or that a segment of the community has not been convinced of the merit of the program and the applicability of the facilities. The microgravity materials-science program is currently skewed toward the metals and alloys research area (i.e., 32 out of 71 Principal

Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
×

Investigators have expertise in this area) and the electronic and photonic research area (26 Principal Investigators). The current selection procedure has had limited success in developing a broad-based, high-impact research program for either polymeric materials (6 Principal Investigators) or glasses and ceramics (7 Principal Investigators).

Many factors may have contributed to this imbalance in the research program, chief among them the nature of the materials themselves. The nature of the sintering process in ceramics and the viscous character of typical high-polymer melts greatly desensitizes their responses to gravitational acceleration, making the value of a microgravity environment in experiments on these classes of materials less obvious than on metals and semiconductors. The underrepresentation of polymeric, glass, and ceramics materials research within the materials-science microgravity program may thus result from a perceived lack of benefits of the environment by these research communities.

Promising areas of microgravity research do exist in these areas, however. To increase their participation, the communities must be effectively informed of the potential benefits of the research program as well as opportunities for participation. NASA needs to develop effective outreach methods to establish links to the best and brightest members of the community and thus to promote an understanding and appreciation of the microgravity research program, the opportunities it offers, and the ways researchers can make contact with relevant personnel within the NASA-affiliated programs and organizations.

NASA must also determine how programs of microgravity research in these areas can best be identified and developed given a flight schedule that provides limited opportunities and requires lengthy lead-times. The current average time to reach flight status—seven years—is an extremely long event horizon for a senior scientist and an eternity for a junior one. The time factor is especially important if the NRA process is to attract the best possible proposals. To ensure the strong growth of the program and the selection of cutting-edge research, topics and areas previously identified by NASA for support must be continually challenged by new program ideas. The strongest possible programs will only evolve through broad-based, open competition.

Recommendation. Although the first priority in selection must always be scientific merit, the microgravity materials-science program should be proactive in developing an effective outreach program (e.g., via organized sessions at professional society meetings) that conveys

Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
×

the benefits of the microgravity research program and stimulates proposals from segments of the materials research community that appear to be underrepresented in the current research portfolio.

In the opinion of the committee, identifying research opportunities in ceramic, glass, and polymeric materials and disseminating them to the targeted communities would be aided by increasing the representation of these research areas on the DWG, decreasing the representation of recipients of NASA funds, and eliminating representation of NASA employees. The DWG has made significant contributions to the materials-science microgravity program, but its membership is currently weighted toward metallurgical and semiconductor research with some ceramics representation and no polymer or biomaterials representation. Experts in those fields are needed to identify high-impact research opportunities, develop an active program in those areas, and ensure that the SSFF Core is applicable to their needs. A large number of the researchers on the DWG have also received NASA funding to conduct microgravity research. Although NASA made a concerted effort to limit this number, many of the members have applied for and received microgravity research grants since joining the DWG. Two are also NASA employees. NASA is attempting to introduce a protocol for rotating a third of the DWG each year and for holding regular biannual meetings.

Recommendation. The membership of the DWG should be reconstituted so that its collective expertise covers not only the scientific areas of the current microgravity experiments but also all materials-science areas that could benefit from microgravity research (e.g., ceramics, glasses, polymers, and biomaterials). To ensure objectivity, the MRD should also institute and vigorously maintain a protocol that ensures that the membership of the DWG is balanced between recipients and nonrecipients of NASA funds (e.g., 1:1) and that the DWG is independent of NASA personnel who could be directly involved in the program.

Space Station Furnace Facility Core Capability

The initial SSFF Core concept was devised during the late 1980s and early 1990s based on recommendations from the DWG; the SSFF Intercenter Science Advisory Panel, which consisted of two

Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
×

representatives from the NASA Langley Research Center, one from the NASA Marshall Space Flight Center, and one from the NASA Jet Propulsion Laboratory; five public workshops; and a study by Teledyne Brown, a hardware fabricator for NASA with headquarters in Huntsville, Alabama. The SSFF Science Working Group (SWG) was formed in 1995 to provide advice directly to the SSFF project scientists during the development and early operational stages and to provide guidance on the functional and operational design. The SWG consists of 22 members from government, academia, and industry. SWG members are appointed for two years, and two SWG members are on the DWG. The SWG has met twice: once in March 1995 to review the SSFF Core concept prior to its Critical Design Review and once in March 1997 to review the project status and assess potential new science requirements. Although the SWG has a protocol for rotating its membership, it has some of the same problems as the DWG: significant weighting towards metals and electronics research and a large representation of NASA employees and recipients of NASA funding.

Recommendation. The SWG should have expertise that covers all of the classes of materials likely to be the subject of microgravity experiments. To ensure the objectivity of the SWG, a protocol should be developed that will ensure a proper balance between recipients and nonrecipients of NASA funds and independence from NASA personnel who may be directly involved in the program.

The committee did not have the expertise to assess the perceived cost/benefit advantages of a SSFF Core by providing a common experimental platform. The committee believes, however, that hardware integration with the SSFF Core could shorten instrument-development time by providing standardized interfaces—both in space and on the ground—to which researchers and equipment designers could efficiently and accurately respond. Over time, these standard interfaces would also permit the accumulation of experience that could be passed on to new users and provide them with the lessons learned by prior investigators.

The current SSFF Core concept was intended to function as a dedicated facility for high-temperature materials-science research. The question now is whether its capabilities can be extended to permit it to become a general facility for microgravity research in materials science and engineering. Most of the scientific and engineering issues

Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
×

of concern in high-temperature materials processing have counterparts in more modest temperature ranges. All experiments in microgravity materials science and engineering will require data input/output and storage capabilities, control hardware, power distribution, and active vibration isolation. The current SSFF Core concept has all of these capabilities, and, therefore, there is every reason to believe that the Core, with some redesigning, could accommodate important experiments in more broadly defined areas of materials science and engineering. Although the committee can only speculate about microgravity research in areas other than those for which the Core was originally designed, any concerns are likely to be more than offset by the broader range of experiments that could become possible and materials classes that could become involved.

Recommendation. To expand the range of experiments and classes of materials that the SSFF Core can support, the current concept should be adapted to serve a broader range of experimental instruments than the modular furnaces for which it was originally designed.

To support this expanded research program, NASA should consider making the following modifications to the current SSFF Core concept:

  • re-examining all equipment in the current SSFF Core concept in terms of its applicability to the broadest range of materials research areas and experiments
  • extending the temperature-control capabilities to lower temperatures
  • adding capabilities to support containerless experiments
  • installing a suitable vacuum system
  • accommodating (1) small quantities of other gases (e.g., oxygen or air) within safety guidelines, (2) fire-suppression systems so oxidizing gases could be used, (3) larger quantities of gases, and (4) control elements for gas handling (e.g., mass flow control and venting systems control)
  • adding liquid-mixing and liquid-flow control capabilities for materials research involving a liquid state
  • re-examining the adequacy of the power supply to produce the requisite high temperatures, levitation, and damping

The committee believes that some aspects of polymer, ceramic, and glass research merit serious consideration for inclusion in the

Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
×

microgravity materials research program, but enlarging the program raises two issues of concern. First, the desire to expand the program could unintentionally cause the implementation of a quota system. In expanding the range of the microgravity research program's interests, NASA must not allow diversity to become a driver unto itself, which could result in the displacement of projects with great potential value or impact. Second, the current SSFF Core concept is best suited for experiments on metals and semiconductors in which high temperatures and their rates of change are the principal variables. The desirability of substantially redesigning the SSFF Core hardware systems to enable research on polymer, ceramic, or glass materials requires careful consideration. Redesigns should probably be undertaken in areas where modifications will clearly enable a broader program with little effort or collateral costs. Any substantial redefinition of the microgravity materials science research plan or redesign of the SSFF Core must be driven by the needs of a coherent, broad-based, high-impact program of materials research carried out in a microgravity environment, and any potential studies of polymeric, ceramic, and glass materials must be evaluated in the context of this larger research program.

Recommendation. If potentially high-impact polymeric, glass, and ceramic materials research is to be pursued, NASA should make it a priority of the reconstituted DWG and SWG to determine which programs have the highest potential for making significant contributions to the field of microgravity materials science research, what ranking among these programs is appropriate when they are placed in competition with each other, and what design modifications to the SSFF Core concept should be implemented to accommodate these new areas. These determinations will only be valid, however, if they are performed by new working groups with representatives from all the possible areas of microgravity materials science research and thus can debate the issues in a balanced and objective manner.

References

NASA. 1996. NASA Microgravity Materials Science Conference: Proceedings of a Conference Held at Huntsville, Alabama, June 10-11, 1996. NASA Conference Publication 3342. Huntsville, Ala.: Marshall Space Flight Center.

Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
×

NRC (National Research Council). 1992. Towards a Microgravity Research Strategy. Space Studies Board, National Research Council. Washington, D.C.: National Academy Press.

NRC. 1995. Microgravity Research Opportunities for the 1990s. Space Studies Board, National Research Council. Washington, D.C.: National Academy Press.

Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
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Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
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Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
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Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
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Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
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Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
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Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
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Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
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Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
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Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
×
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Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
×
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Suggested Citation:"Executive Summary." National Research Council. 1997. Future Materials Science Research on the International Space Station. Washington, DC: The National Academies Press. doi: 10.17226/5971.
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