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VI Assessment of the Need for a CDSF In addressing the issues posed in its charge (Appendix A), the committee found itself faced with a multitude of related questions. To evaluate properly the need for a CDSF or for any additional flight capabilities beyond existing and planned facilities, it was necessary to examine the current national program in microgravity sciences and to investigate the scientific and commercial potentials of microgravity research. In recent years there has been an abundance of literature to the effect that flight opportunities were insufficient and that U.S. microgravity scientists were at a disadvantage internationally. Certainly this was true during the flight hiatus after the Challenger accident. In response to these critiques, NASA clearly has taken positive actions to increase both microgravity budgets and flight opportunities. The committee was confronted with questions of readiness, that is, whether the state of the art in the emerging area of microgravity sciences was such that a human-tended free-flyer represented the most effective approach to future research; whether the state of automation, robotics, and telescience would enable scientists to make rapid progress; and whether there existed adequate reliable, flight-tested, general purpose or easily adaptable equipment. The committee also faced questions concerning the optimum timing for additional government-sponsored facilities; whether projected payloads were likely to materialize and, if so, whether they would fill manifested flights; and questions regarding the resources that would be needed to effectively utilize a human-tended free-flyer should it come into being. These questions are discussed in the sections that follow. 47

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REQUIREMENTS VERSUS CAPABILITIES The study committee examined the planned and anticipated microgravity research and manufacturing requirements of the federal government and commercial users prior to the initiation of Space Station operations. It found that almost all of the proposed activities are supported by NASA under microgravity research programs intended to develop knowledge in this new field and to foster potential commercial applications developed by universities and industries affiliated with the NASA Centers for the Commercial Development of Space, and/or using Joint Endeavor Agreements or Space Systems Development Agreements with industry. In addition, NASA is expected to provide the major U.S. in-space microgravity research capabilities by means of its Shuttle-based facilities in the 1992-1997 time frame. Both the NASA microgravity program and manifesting for the Shuttle are dynamic and evolving. Therefore, the analyses in this report are based on information available in early 1989. There is general agreement that until recently NASA had not been effective in providing adequate access for researchers to the microgravity environment. Over the past 18 months, however, NASA has responded to the recommendations of its Microgravity Materials Science Assessment Task Force and others for enhancing U.S. activities in microgravity research by significant budgetary increases and by planning more flight opportunities aboard Shuttle-based facilities. Indeed, roughly 18 Shuttle equivalent missions for materials and life sciences microgravity research are tentatively manifested by NASA for the period prior to FY 1995. Experiment space is essentially booked for flights leading up to USML-1 (manifested on flight STS-54 in early 1992), although the payloads for USML-1 are not yet firm. Specific microgravity experiments are not yet designated for flights after STS-54. Thus it appears there may be considerable flexibility to accommodate new experiments that might be developed over the next few years. It also should be noted that there will be opportunities for additional secondary payloads to be manifested on earlier flights, due to the Shuttle weight margin reserves that are released at a certain point before each flight. In examining the available and proposed facilities (see Chapter 4), the committee probed whether limitations of existing capabilities (the most important being g level, duration, and power) seriously affect the quality of pre-Space Station experiments; it found few serious constraints in these areas. Indeed, the committee believes that over the next few years, capability limitations notwithstanding, the nation should have a challenging program under current plans of what appear to be meritorious experiments that promise to yield useful new scientific data. Acceleration, or g Level Although in a number of cases the need for a high-quality microgravity environment remains to be demonstrated, the quality or "cleanliness" of 48

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the microgravity environment is of concern to many scientists. On a free-flyer, much depends on the flight mode. If a free-flying platform is only periodically tended by humans, its environment will probably display a lower gravitational level and contain fewer disturbances than either the Shuttle or the Space Station with their attendant human activity and periodic thruster firings. Also, the low-frequency, or quasi-static, components of the acceleration vector, which play the major role in affecting many types of microgravity experiments, are themselves sensitive to the platform's orbital parameters, flight path, and vehicular orientation. Since the specific CDSF design has not been determined, there is an insufficient basis to make detailed quantitative comparisons of its expected microgravity environment with that of other orbiting vehicles. Some preliminary data suggest, however, that the probable center of gravity of a Shuttle-CDSF configuration (used in human-tended operations) is likely to lead to a less ideal microgravity environment for experiments than would be realized on the Shuttle or CDSF alone. In trying to determine whether existing facilities will meet desirable experimental requirements, it appears there may be some compound and alloy-type electronic and optoelectronic crystal growth experiments that require very low microgravity levels that may only be approached by a free-flyer, as discussed earlier in the requirements section. Duration As the microgravity program matures and longer on-orbit processing times become necessary for extremely slow processes like vapor-phase and solution crystal growth, a long-duration free-flyer with enhanced energy and power doubtlessly will be desirable. Over the next decade or so, however, NASA's microgravity program is structured along an evolutionary path that includes enhanced flight opportunities on Spacelab and other Shuttle-based carriers followed by use of the Space Station; equivalent detailed plans for other federal agencies do not yet exist. Shuttle flights will be configured around mission rules that will provide a beneficial microgravity environment. Secondary payload opportunities, for example on the Shuttle middeck, may have less favorable mission rules, but judicious selection of the experiments should lead to scientific progress. Use of an Extended Duration Orbiter to lengthen planned missions should provide significant data on long-duration processes prior to the Space Station. At the same time, the advent of a CDSF in the next five years also could possibly accelerate progress along the evolutionary path by providing longer orbital processing times for those experiments that are automated or designed to use teleoperation. The projected number of classes of experimenters requiring high peak power, that is, greater than 2.0 kW, is small with the exception of those 49

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concerned with experiment facilities being designed for the Space Station. However, there may be conflicts among high-power users in some operations on Shuttle-based facilities. The highest power consumers are the furnace and levitators planned for flight on Spacelab in support of containerless processing experiments. Problems arising from users requiring high power in conflict with one another can be addressed to a significant degree by efficient manifesting and timelining using the EDO. The total peak power available to Shuttle-based experiments is approximately 7.7 kW for 15 minutes every 3 hours; average power is 3.4 kW (on Spacelab). While the peak power duration can be extended by use of an EDO, the amount of power available at a given moment remains limited by the current-carrying capacity of the Shuttle's wiring. ADEQUACY OF ANTICIPATED FLIGHT OPPORTUNITIES The committee sought and based its deliberations on input concerning the maximum microgravity research activity that might reasonably be undertaken in the interim period preceding the Space Station. As was noted earlier, there is necessarily some softness in the estimates for commercial demand and for scientific investigation given that the time frame exceeds that for which completely reliable projections are possible. However, it is the committee's view that these estimates are higher than will be actually achieved. Therefore, the analysis of flight capabilities needed to meet these estimated requirements is conservative. In any event, additional insurance against shortfalls in capabilities to address unanticipated increases in demand is likely to be available if one or more of the proposed commercial facilities discussed in Chapter 4 comes to fruition. During meetings with the providers of the proposed facilities, it became evident that they will rely on NASA to supply a large portion of their payloads. As earlier indicated, NASA has manifested an increased number of microgravity-related Shuttle missions through the mid-1990s. The committee believes that the overall annual Shuttle flight rates assumed by NASA are not likely to be achieved. Thus, there is likely to be some loss or slippage of microgravity research opportunities during this period unless some presently manifested payloads, for example from the Department of Defense, do not materialize. The committee believes that, barring a drastic reduction in flight rates from the planned 13 or 14 missions per year shown in the current manifest for 1993-1994, the microgravity research community should have adequate flight opportunities to carry on a meaningful research activity. In the event of Shuttle flight rate reductions, NASA should make an effort to ensure that microgravity flight opportunities do not suffer disproportionately during the required remanifesting. Over the long term, it would be highly beneficial for NASA to build a contingency reserve (e.g., on the order of 20 percent) into its manifesting process to compensate for potential flight rate shortfalls. 50

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In some respects, the dilemma of the nation's microgravity scientists is comparable to that of its other space scientists who faced a long hiatus in flight opportunities that resulted in a backlog of missions needing to be flown. However, flight opportunities are being made available. Moreover, the nature of current microgravity research in materials, fluids, and life sciences is such that the results of certain basic science missions are needed before a follow-on research and development strategy can be clearly mapped out; in addition, human interaction with experiments is highly desirable if not necessary. A&R AND TELESCIENCE CONSIDERATIONS The gaps between what is needed for a human-tended free-flyer and what currently exists are not so much in the availability of the technology as in how it is applied (with the exception of repair of complex machinery). Terrestrial automation and robotics is generally sufficient for remote monitoring, reconfiguration, and simple modification and repair of microgravity experiments provided that: • A&R and telescience specialists and microgravity researchers communicate and work together to a greater degree than in the past, • microgravity experiments are designed to accommodate A&R and telescience, and • prelaunch checkout also includes systematic trials with A&R and telescience to observe normal phenomena, detect failures, and make modifications and repairs. Again, it should be noted that there currently are not adequate resources allocated to implement A&R and telescience in the array of planned and projected NASA microgravity experiments. RESOURCE CONSIDERATIONS Development of the capability to conduct microgravity research and applications activity with a CDSF will require commitment of resources by the U.S. government for the lease (or purchase) of the facility itself and also for the development of all that will go into the facility: furnaces, telescience equipment, other support equipment, and, of course, experiments (since NASA funds the vast majority of U.S. microgravity research). This latter commitment is especially important to keep in mind when considering the resource implications of a CDSF. It was beyond the scope of the committee's charge to calculate the total cost of a CDSF to the U.S. government. However, some indication of the magnitude of the resources involved can be gained by noting that a total CDSF lease cost to the government of $700 million represents about five times the total annual NASA microgravity budget (currently at 51

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approximately $150 million per year). Moreover, the above-mentioned CDSF cost estimate may well prove a lower bound on the total cost. In addition, as noted above, the budget for microgravity experimentation would have to be considerably enhanced to provide equipment for experiments along with automation for a free-flyer. ECONOMIC AND COMMERCIAL CONSIDERATIONS Based on historical experience, the broadened comprehension generated by innovative research ultimately will have commercial consequences. There are few examples of a widened span of process control that have not brought a corresponding payoff, from the time that hotter fires fed by air blasts made smelting iron possible. The extra dimensions (e.g., microgravity, vacuum) opened by space are almost unprecedented as variables in industrial processing. Their exploitation will be slow and laborious, both as a result of the novelty of the environment and the high cost that tends to be inherent in space-based activities. Nevertheless, given the competitive nature of the global economy, it is in the national interest that the existing long-term investment in space by the United States be exploited aggressively to allow the U.S. economy to benefit from these new capabilities as they become available. Given the high costs, the lead times, and the uncertainties involved in setting up new facilities and developing new markets, it is clear the first returns from this research will grow out of a better understanding of physical phenomena that will allow further optimization of existing Earth-based processes. A much greater level of knowledge (along with reduced cost of access to space) will be required to permit the emergence of a more completely space-based industry. A sound foundation of practical and theoretical understanding must be put in place if industry is to achieve the ability to invest with some confidence in this area. The dollar cost of space activity is another restriction. At a very conservative estimate of $110 million, the price of the payload bay per Shuttle flight represents some five percent of the National Science Foundation's annual budget. For a commercial enterprise, this translates to a multimillion dollar cost per experiment, with restricted access, stringent weight and volume limitations, and at best only limited power. Unsurprisingly, there have been no takers, except on terms that transfer the cost of space access to NASA. Recognizing these constraints, there nevertheless is a broad range of facilities to allow simulation or exploration of the microgravity environment of space. These range from relatively simple capabilities, including ground-based drop tubes, to very complex ones such as the Shuttle-borne Spacelab. Their costs vary from a few thousand dollars per test up to millions, and they differ in accessibility, ease of use, and utility. The need for new facilities must be measured against these existing assets to determine what extra capabilities are needed and at what cost. The existing facilities are described in detail in Chapter 4. 52

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Although it was not the focus of this study, the question of opportunity costs arises repeatedly. Is a government guarantee of at least $700 million as an anchor tenant in a CDSF the most beneficial expenditure of that amount for microgravity research (considering an annual program budget of approximately $150 million for MSAD, life sciences, and commercial programs) or, for that matter, for the national space program? At issue is whether a CDSF fills a national need of sufficient import to warrant the investment. In summary, once initial scientific understanding of the underlying microgravity influences is achieved, the promise of in-space research and applications activity for scientific and commercial benefit is great. The value of the program may eventually exceed its cost in terms of potential scientific breakthroughs or in terms of the U.S. competitive posture vis-a-vis Europe, Japan, and the Soviet Union. Although the potential benefits to the nation lie in the future, it is important to explore this new frontier of human knowledge and to build the foundation for eventual private exploitation of the space environment. NEED FOR A CDSF IN THE PRE-SPACE STATION ERA NASA, in its CDSF Request for Proposals in the spring of 1988, described a spacecraft similar to the Industrial Space Facility. Studies since that time have considered a spacecraft roughly 20 percent the size of the earlier concept, as well as other tradeoffs. Thus, the committee approached its evaluations without preconceptions of what a CDSF might be and examined a number of potential facility types. Clearly, its dimensions could be scaled to the anticipated need and its timing made flexible on the same basis. Only a few functional requirements would appear to be essential. If a CDSF were to be built, its experiment accommodations should be compatible with those of the Space Station, it should be optimized for telescience operations, and it logically should be accessible from the Shuttle and/or Space Station for payload tending by humans. The committee did not address costs or the implications of commercial development because those are the subjects of a simultaneous study under the auspices of the National Academy of Public Administration. Considering the requirements presented in Chapter 3, the capabilities described in Chapter 4, and the issues discussed above, however, the committee does not foresee a need for a U.S. human-tended free-flyer in the period prior to the Space Station to meet microgravity research or manufacturing requirements. Anticipated microgravity experimental activities requiring a human presence can be adequately conducted using current Shuttle-based facilities during the 1992-1997 time period, assuming reasonably reliable access to space. At the same time, the committee is concerned that microgravity research and planning for transition of this research to the Space Station receive adequate visibility in future NASA planning. This would be especially true should 53

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all of the expected Shuttle flight opportunities not materialize. A delay in the deployment of Space Station Freedom of one to two years because of policy, budgetary, schedule, or transportation problems would not affect the committee's conclusion. A more extensive delay that would jeopardize expected advances in microgravity sciences would warrant a reconsideration of the need for a CDSF or other free-flyer. The committee notes, however, that a human-tended free-flyer is not an adequate long-term substitute for particular microgravity research capabilities (e.g., continuous manned interaction, high available user power) planned for the Space Station. Another potential use for a CDSF to which the committee has given consideration is as a platform for technology development and demonstration needed for the Space Station. It also has been argued that a CDSF would prove a useful operations testbed for Space Station systems. However, the committee remains unconvinced by these arguments. Given that the CDSF is not likely to fly until at least 1993 and the assembly of the Space Station on orbit is scheduled to begin in 1995, the CDSF would not have more than a marginal impact on Space Station technology development and demonstration. The committee also considered the benefit of having a CDSF as a form of "insurance policy" against Shuttle flight rate reductions, the loss of existing microgravity research facilities (e.g., Spacelab), or delay in initial utilization of the Space Station. As indicated earlier, the ability of a CDSF to stay in orbit untended for long periods to compensate for reduced Shuttle flight rates will not be of significant value until the state of microgravity experimentation is considerably more advanced, including the effective use of A&R and telescience. Furthermore, the committee is skeptical of an insurance policy for which the annual cost of the "premium" (i.e., the CDSF facility lease/purchase price and associated experiment/equipment development costs) exceeds the annual cost of the "insured" (i.e., the NASA microgravity program, currently budgeted at about $150 million per year). The committee does not wish to leave the impression that the concept of a long-duration free-flyer for microgravity research is without merit. The question to be asked is when such a free-flyer might be of benefit to the nation, and the level of maturity of the U.S. microgravity program is a key to answering this question. Microgravity sciences are in an embryonic stage, and it is difficult to anticipate their future needs and to develop a long-term research strategy. For example, the uncertainties surrounding the influence of gravitational acceleration on fundamental heat and mass transport near reaction zones and internal interfaces make it difficult to plan processing strategies and obtain optimum results. Our limited basic understanding of and experience with fundamental fluid physics and materials behavior in reduced gravity severely restricts practical applications at this time. This pervasive situation, recognized by OCP, probably means that the development of viable commercial processes in space will take nearly a decade, although the committee acknowledges the possibility of early, serendipitous research successes that could advance the period by several years. 54

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The value of having some kind of free-flyer concurrent with mature operations of the Space Station seems apparent. Such a facility should be readily accessible from the Station and be compatible with it, yet have the advantages of a "cleaner" microgravity environment, and should be able to take advantage of expected advances in A&R and telescience. Indeed, plans already exist for a Space Station Man-Tended Free-Flyer to be developed by the European Space Agency. The committee's analysis indicates 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. Free-flyers eventually will be needed in the performance of microgravity R&D and applications work, but their use will be predicated on developing the knowledge base, hardware systems, and appropriate A&R and telescience needed to make them practical. NOTES 1. Todd, Dunbar, Slichter, and The Task Force on the Scientific Uses of a Space Station (TFSUSS). 2. Dunbar, 1987, p.7. For critical assessments of the available capabilities for microgravity research, see also Slichter and Todd. 3. Langley Research Center, 1989. 55

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