Toward a Microgravity Research Strategy (1992)

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Toward a Microgravity Research Strategy (Chapter 3) Toward a Microgravity Research Strategy 3 The Conduct of Microgravity Research Some aspects of microgravity research are unique. Paramount is that much of it takes place in an environment remote from Earth and, therefore, will be practically inaccessible except when specific missions are flown. Coupled with this inaccessibility is the enormous cost of such research, both in initial investment and in operating costs, especially when humans are on board. Details of these distinctive aspects are addressed in the following sections. INSTRUMENTATION The conduct of microgravity research necessitates developing scientific equipment that is capable of withstanding the stresses of launch and reentry and of functioning reliably REPORT MENU and safely in space. Although it is highly specialized, such equipment is distinguishable from NOTICE other space hardware because of its functional diversity. MEMBERSHIP SUMMARY Generally, equipment serves one of two purposes: synthesis and processing of CHAPTER 1 specimens or observation and measurement of phenomena. Important considerations CHAPTER 2 include size and volume; means for the insertion, manipulation, removal, and storage of CHAPTER 3 specimens; ambient atmosphere; thermodynamic (e.g., temperature, pressure, composition) CHAPTER 4 range and sensitivity; observational capabilities (including photographic or video recording); APPENDIX A power needs; thermal dissipation; and, safety issues. This degree of complexity places APPENDIX B exceptional burdens on design, operational reliability, accommodation and integration in APPENDIX C APPENDIX D larger systems (e.g., the Shuttle or a space station), lead time needed for development and APPENDIX E construction, and cost. APPENDIX F The interaction of users with this equipment is quite different from their interaction with many other space instrument. Whereas repetitive observations and large data sets are typical of space hardware in the observational sciences, the. user of microgravity equipment must often interact with the equipment to change experimental parameters from run to run. Furthermore, the data from an experiment are often contained in a specimen that has been synthesized or processed, thus requiring complete characterization of the specimen before continuing with the next experiment, Sometimes statistical design of experiments involving multiple .samples and varied parameters can be used to increase efficiency, but this requires reproducibility and parameters that are well controlled, a rarity for space experiments so far. file:///C|/SSB_old_web/cmgr92ch3.htm (1 of 9) [6/18/2004 11:09:18 AM] 

Toward a Microgravity Research Strategy (Chapter 3) Finally, there is the question of multiuser versus specific-user equipment, In principle, general multiuser equipment would seem to have the advantage because it could be designed arid built in advance and would be economical because of the large numbers of users served, In practice, this is not usually the case. Trying to design in advance equipment that will serve the anticipated needs of multiple users entails large amounts of engineering design and necessitates many compromises, often resulting in equipment that is satisfactory to no one and is extremely expensive. An alternative approach is to design and build equipment that is specific to a particular experiment or class of experiments, in close cooperation with the principal investigator(s). Although this approach requires long lead times and the resulting equipment many not be useful elsewhere, the equipment will satisfy the intended need; such an approach is thus a better overall strategy. MANNED VERSUS ROBOTIC INTERACTION It is possible to conduct microgravity experiments in a number of modes, the extremes being continuous manned interaction (similar to laboratory work on Earth) and robotic interaction (full intelligent automation). Each of these has advantages and disadvantages. Hybrid modes are also possible and usually more realistic. An optimum program will use a mix of modes that will depend on the set of experiments to be accomplished, the instantaneous state of technology, and cost-effectiveness. Continuous manned interaction has the advantages of allowing for better observation and analysis of the experiment and better dexterity and flexibility in correcting any malfunctions, servicing, tuning, or adjusting for parameter changes. Unfortunately, this is the most expensive mode of operation, because it necessitates a life support system for humans and stringent safety standards for all of the equipment. Some human skills can be utilized by remote observation and control, with occasional access granted for major servicing and repair; of course, limited access can be a serious handicap for some experiments. A free-flying spacecraft with a combination of robotic interaction and manned remote control can lead to a reduction in the stray vibrations or accelerations often identified as artificial gravity, or "gravity-jitter," Some of these result from robotic movements, comparable to those attributable to human movements. Disturbances from other experiments are possible; however, disturbances from docking, maintenance activities, and life support systems would be absent. Some experiments will not require extremely low levels of gravity, only well-monitored, reduced levels. A fully automated (robotic) free-flying spacecraft can offer major cost advantages. Precise control of the cabin environment is not needed, and toxicity resulting from hazardous materials is a much less significant concern. Moreover, safety standards are considerably less stringent because catastrophes will not normally result in the loss of human life. In summary, some experiments require the advantages of a space station laboratory but others can be done as well or better, and certainly at much less expense, in a free-flyer configuration. file:///C|/SSB_old_web/cmgr92ch3.htm (2 of 9) [6/18/2004 11:09:18 AM] 

Toward a Microgravity Research Strategy (Chapter 3) RANGE OF MICROGRAVITY FACILITIES Microgravity conditions can be found in a broad range of facilities, ranging from relatively simple, ground-based drop tubes to complex facilities such as Spacelab on the Space Shuttle, The costs of these facilities vary from a few thousand to millions of dollars, and they differ in accessibility, ease of use, and utility. The experimenter's choice of these facilities should be based on specific research needs as well as return on investment. For certain experiments, a high-quality microgravity environment is essential. For others, a rather noisy, low-gravity environment will suffice. In some situations involving fluids, low gravity can be simulated by matching densities to reduce buoyancy forces, but this approach restricts greatly the set of fluid properties and the phenomena .that can be'studied. Since microgravity research is in an embryonic stage, it is difficult to rely on any one facility for experimentation. Drop tubes and towers, aircraft flying parabolic trajectories, and sounding rockets provide test periods of several seconds to a few minutes. These facilities supply representative gravitational accelerations of 10-2 gE for the KC-135 airplane, 10-5 to 10-6 gE for sounding rockets, and 10-6 gE for drop tubes and are available to U.S. investigators at sites developed and operated by the government (see Figure 1). NASA's sounding rocket program, oriented toward astrophysics and space science payloads, has seen renewed microgravity usage under the direction of NASA's Office of Commercial Programs. A four- stage sounding rocket, with improved capabilities of up to 20 minutes of microgravity and a 1,500-km altitude, is under consideration for members of the centers for the commercial development of space (these centers are discussed below, under "Commercial Programs"). Experiments in sounding rockets, managed by NASA's Office of Commercial Programs, were resumed in 1989. FIGURE 1 Characteristic duration and acceleration levels. SOURCE: Microgravity Science and Applications file:///C|/SSB_old_web/cmgr92ch3.htm (3 of 9) [6/18/2004 11:09:18 AM] 

Toward a Microgravity Research Strategy (Chapter 3) Division, NASA. Orbital facilities include the Space Shuttle, recoverable capsules launched on expendable vehicles, free-flying spacecraft, and space stations. These facilities offer enhanced resources in terms of volume, power, cooling, crew time, and data management, but, most importantly, they enable test times to be extended to days and perhaps weeks (for an Extended Duration Orbiter). Accelerations are in the 10-4-gE range at the middeck of the Shuttle; this location has been used effectively by experimenters because of the ease with which the crew can be integrated and the potential ability to achieve late preflight and early postflight access. Dedicated pressurized Spacelabs, located in the payload bay of the Shuttle, can accommodate several experimenters working simultaneously. Missions having a large concentration of microgravity research experiments are scheduled to begin flying in 1992. Spacelab provides up to 7.7-kW peak power for 15 minutes every 3 hours and 3.4-kW maximum continuous power. Each flight can hold up to a 4,500-kg payload, with an overall volume of 8 m3 available to users. These provisions greatly extend the researcher's ability to perform more experiment, and to conduct experiments of longer duration with programmed distributions of power and crew time. Choosing the most cost-effective, low-gravity experiment capability is very important. Experiments that can be flown on less expensive facilities should be flown on those facilities. For example, experiments that can be carried out adequately on sounding rockets should not be flown on Spacelab or Space Station Freedom. The hundreds of hours of U.S. and other experiments conducted in orbit have offered limited insights into the myriad problems that exist. The limitations have been considerable in comparison to the research procedures performed regularly on Earth in other areas. Many failures have been caused by inadequate knowledge of the space environment; restrictions on the weight, size, power, experience, and expertise of the mission specialists and astronauts; and the quality and duration of the microgravity. Generally speaking, developments in microgravity research, as in any new field of research, will require additional thousands of test hours in order to achieve reproducibility, process control, improvements, and verification of results. Given the high costs, long lead times, and uncertainties involved in developing and sustaining both the facilities and the scientific interest of this research community, it is clear that government funding for access is indispensable, as it is for development of the instruments and for rigorous selection of the experiments. The committee recommends that a concerted effort be made to classify experiments according to their minimum needs in order that the most cost-effective access to reduced gravity will be used. MICROGRAVITY RESEARCH OUTSIDE THE UNITED STATES Programs in microgravity research are conducted by foreign countries also, most notably the member nations of the European Space Agency (ESA), the former USSR, and Japan. Europe (the ESA and particularly Germany) holds a strong position in microgravity research compared with the United States. After a greater initial investment by the ESA and Germany, Europe continues to fund microgravity research at a level equivalent to U.S. funding. The Europeans have demonstrated greater efficiency in obtaining both quantitative file:///C|/SSB_old_web/cmgr92ch3.htm (4 of 9) [6/18/2004 11:09:18 AM] 

Toward a Microgravity Research Strategy (Chapter 3) and qualitative results to date and hold a substantial lead in the design of microgravity experimentation instrumentation, for example, Mephisto (a solidification furnace) and space bioseparation (for biological purification). Europe's deperidence on the United States for access to space has been a weak point in its microgravity research. Because of the lack of NASA flight opportunities, the Europeans have established an extensive program of short- duration experiments with a diverse infrastructure (i.e. drop towers, aircraft for parabolic flights, sounding rockets, and high-altitude balloons). The former USSR put the MIR space station into orbit in 1986 and has had opportunities to conduct microgravity research for long durations (on the order of years) and with extensive manned interactions. From sketchy reports of' the results and discussions with a few former Soviet researchers, this committee has concluded that this program, with minor exceptions, mirrors that of the West. The Japanese government and industry have targeted reentry capsules as a strategic technology for development and acquisition during the 1990s. Japan's National Space Development Agency and its Ministry of International Trade and Industry are monitoring the U.S., German, and ESA programs closely with the intention of entering into collaborative arrangements, for example, development of the Japanese Experiment Module for Space Station Freedom. The Japanese also have their own programs involving sounding rockets and parabolic aircraft flights. COMMERCIAL PROGRAMS Commercial engagement in microgravity research began in 1980 with the initiation of three new legal vehicles for joint government-industry association on a no-exchange-of- funds basis. The general concept is that industry is to supply the experimental capabilities while NASA is to provide the spaceflight opportunities. The goal is to encourage the early involvement of industry in microgravity space experiments that would lead to its long-term investment in using the space environment for commercial purposes. A list of the joint arrangements as of 1989 can be found in the NRC's Report of the Committee on a Commercially Developed Space Facility.1 As of the present time, no commercial endeavors have matured to the stage that there are full paying customers for space transportation and operation services, In addition to space experiment incentives, NASA's Office of Commercial Programs, in cooperation with industry, has established centers at several universities for the development of commercial space experiments.2 Started in 1986, these centers for the commercial development of space (CCDS) were given a five-year period in which to become independent by attracting increased industrial funding. The NRC Committee on a Commercially Developed Space Facility proposed a number of space facilities that would enable further initiatives in commercial microgravity experiments.3 In the late 1980s, some proposals were made by industry to supply a free- flying facility that would accommodate microgravity experiments in return for a guarantee by NASA to lease the facilities for government use as well. However, the NRC committee commented that ". . . having greatly enhanced access to space up to five years earlier than the Space Station is anticipated actually would add little toward speeding space commercialization based on exploitation of the microgravity environment" (p. 55). Hence, file:///C|/SSB_old_web/cmgr92ch3.htm (5 of 9) [6/18/2004 11:09:18 AM] 

Toward a Microgravity Research Strategy (Chapter 3) the commercially developed space facility concept was not pursued by NASA. Overall, the various NRC committees reviewing the microgravity program have not envisioned any near-term commercial opportunities.4,5 No indications surfaced in 1991 to change these views based on the results of NASA's program or the foreign programs. Some disturbing trends are becoming evident in the commercial programs for microgravity experiments. There is competition between scarce spaceflight opportunities and the university research funded by NASA's Division of Microgravity Science and Applications. The zeal to provide commercial "customers" priority access to space may jeopardize opportunities for worthy space experiments that have been on hold for a long time. Furthermore, although commercial experiments are regarded by the centers and their sponsors as proprietary and therefore not subject to peer review, there is an increasing suspicion that their quality is lower than that of traditional university research. This suspicion arises because some companies have not pursued their investment in the joint agreements and have not published their results, even though they have no further commercial interest in the work. Work that has appeared has not been published in the archival, peer-reviewed literature. Accordingly, the CMGR recommends that a thorough technical review of the centers for the commercial development of space be conducted to determine the quality of their activities and to ascertain to what degree their original mission has been accomplished. Another committee has concluded that the microgravity environment should "be considered primarily as a tool for research and secondarily as a manufacturing site" since "significant demands for manufacturing opportunities are unlikely in the near term" (p. 1).6 The CMGR agrees with this assessment and believes that a strong and comprehensive base of research and technology in the microgravity environment must be developed first, on the same basis that it is developed on the ground, before any real commercial opportunities can arise. Furthermore, these opportunities will be primarily in the use of space to understand and improve ground-based manufacturing processes that are sensitive to fluid disturbances of the type that can be studied in space. Finally, the CMGR notes that materials processing and manufacturing in space for the purpose of sustaining space travel and human exploration probably will become more important eventually than materials processing and manufacturing in space for providing products for use on Earth. THE RESEARCH AND ANALYSIS PROGRAM The research and analysis (R&A) program in NASA's Microgravity Science and Applications Division consists of the ground-based research needed to provide the context of knowledge from which the flight program originates as well as the infrastructure required to analyze microgravity experiments in a broader context. The microgravity science program has been rooted historically in the materials processing sciences, with the inclusion of some additional components such as fluid flow, file:///C|/SSB_old_web/cmgr92ch3.htm (6 of 9) [6/18/2004 11:09:18 AM] 

Toward a Microgravity Research Strategy (Chapter 3) combustion, critical-point phenomena, and biotechnology. Many research activities have focused on the modeling and understanding of very subtle phenomena in the fluid state. This work has contributed profoundly to our understanding of fluid behavior and its effects on materials preparation on Earth. However, NASA's R&A program of the future must capture a broader range of interests in physics and chemistry. In addition to expanding the base of the R&A programs, the microgravity program must improve its effectiveness and productivity. The current program includes investigators who have been funded for 13 years in some cases. In addition, many of these investigators have experience with only one or two space experiments. Therefore, the overall health of microgravity science is arguably poorer than that of other comparable scientific endeavors with faster development cycles. The current research program should be reconstituted and refocused in order to revitalize it and to open up new opportunities. The CMGR recommends that NASA apply a set of value criteria and measurement indicators to define the research and analysis program more clearly. Some of the value criteria and indicators that .should be used for the new R&A program are as follows: Value criteria — relevance to other science — significance of potential contributions to important scientific questions — past experience and track record of investigators — ability to develop adequate plans and well-understood requirements for space experiments — scope of effort needed to achieve significant results. Indicators — innovation—novelty, uniqueness — quality—for example, publication in refereed technical and scientific literature — productivity—for example, the length of time taken to execute the experiments in space as compared to a ground-based equivalent; also, the percentage of time that space hardware is actually used — cost-effectiveness—including consideration of hardware development costs, reusability, reconfigurability of hardware, and integration costs on different space vehicles. These value criteria and indicators should be evaluated in the context of other areas file:///C|/SSB_old_web/cmgr92ch3.htm (7 of 9) [6/18/2004 11:09:18 AM] 

Toward a Microgravity Research Strategy (Chapter 3) of physical and chemical sciences to determine the relationship between funding levels and research output over a reasonable period of time (such as three years). The CMGR recommends that the funding level for research and analysis in microgravity science be established as a fixed percentage of the total program of NASA's Microgravity Science and Applications Division in order to build a strong scientific base for future experiments. Past experience indicates that this percentage should be between 30 percent and 50 percent for new science, This percentage dropped from 50 percent in 1981 to 13 percent in 1991 as space hardware expenses grew. There are plans to double the R&A budget over the next five years, which is a step in the right direction; however, the size of the total program its increasing at least at this rate or faster, so that the percentage increase of' R&A- is hardly changing. If more research of higher quality and wider diversity is to he incorporated into the microgravity program, it is imperative that the R&A budget be a larger fraction of the total microgravity budget of NASA's Microgravity Science and Applications Division. REFERENCES 1. Aeronautics and Space Engineering Board. 1989. Report of the Committee on a Commercially Developed Space Facility. National Academy Press, Washington, D.C. 2. Space Applications Board. 1988. Industrial Applications of the Microgravity Environment. National Academy Press, Washington, D.C. 3. Aeronautics and Space Engineering Board. 1989. Report of the Committee on a Commercially Developed Space Facility. National Academy Press, Washington, D.C. 4. Aeronautics and Space Engineering Board. 1989. Report of the Committee on a Commercially Developed Space Facility. National Academy Press. Washington. D.C. 5. Committee on Scientific and Technological Aspects of Materials Processing in Space. Space Applications Board. 1978. Materials. Processing in Space. National Academy of Sciences, Washington, D.C. 6. Aeronautics and Space Engineering Board. 1989. Report of the Committee on a Commercially Developed Space Facility. National Academy Press, Washington, D.C. file:///C|/SSB_old_web/cmgr92ch3.htm (8 of 9) [6/18/2004 11:09:18 AM]