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Impact of ISS Changes on Physical Sciences Research

INTRODUCTION

The physical sciences research sponsored by NASA’s Office of Biological and Physical Research (OBPR) has typically come under four disciplines—materials science, combustion science, fluids science, and fundamental physics—although some overlap occurs between these disciplines. OBPR has a Physical Sciences Division that also supports areas of biology-related or non-gravitational research, such as biotechnology and nanotechnology, that are not discussed in this chapter.1 In the sections that follow, the research sponsored by NASA in these four areas is described, and the task questions relating to implementation of the research on the ISS are considered.

Specialized research racks for physical sciences experiments on the ISS are designed to hold several modules. Each module contains one or more experiments, and in some cases the equipment can be shared. Large projects, such as the-low temperature facility, will be installed in special carriers mounted on the outside of the ISS.

Overall, the cuts made in the NASA/ISS research capability budget since Rev. F were absorbed primarily by the physical sciences research program, whose budget went from $980 million to $576 million, a 41 percent reduction.2 This reduction resulted in the cancellation (or deselection) of 26 of 77 flight experiments, a 34 percent reduction. Most of the deselected experiments, although not yet under construction, were chosen for deletion because the necessary facilities would require near-term expenditures. Scientific merit was not a criterion.

In addition, significant reductions in the scope of the remaining experiments retained have been imposed. In large part the physical science experiments are designed for remote operation and require relatively little crew intervention, so they could in theory be carried out with the smaller three-person crew. However, just the time needed to load an experiment, let alone intervene in an ongoing experiment, might exceed the allotted U.S. crew time (7.5 hours/week). NASA also is planning fewer shuttle flights to the ISS; four per year were recommended in the Young report (IMCE, 2001), greatly constraining the ability to transport materials to be used in the experiments. Finally, the uncertainty surrounding the budget and funding levels is having a negative impact on the scientific community, as principle investigator (PI) funding for scheduled flight experiments is reduced. Given these uncertainties, PIs may seek opportunities elsewhere, thereby jeopardizing the future of ISS science.

MATERIALS SCIENCE

Program Description

The overall goal of the OBPR materials science program is to use microgravity to establish and improve the quantitative and predictive relationships among the processing, structures, and properties of materials used for making products. Materials are inherent in all branches of engineering and have influenced social change profoundly over the course of history. Because gravity plays a critical role in materials formation, it is necessary to understand and control the effect of gravity on the processes used to produce materials, and also to resolve fundamental scientific questions about materials phenomena by

1  

The cell biology research carried out in the biotechnology program is discussed in other sections of this report. Protein crystal growth, also part of the biotechnology program, is not among the subdisciplines covered in this report, although it has been reviewed recently by the NRC (2000a).

2  

From FY 01 budget to Administration’s FY 03 proposed budget.



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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences 2 Impact of ISS Changes on Physical Sciences Research INTRODUCTION The physical sciences research sponsored by NASA’s Office of Biological and Physical Research (OBPR) has typically come under four disciplines—materials science, combustion science, fluids science, and fundamental physics—although some overlap occurs between these disciplines. OBPR has a Physical Sciences Division that also supports areas of biology-related or non-gravitational research, such as biotechnology and nanotechnology, that are not discussed in this chapter.1 In the sections that follow, the research sponsored by NASA in these four areas is described, and the task questions relating to implementation of the research on the ISS are considered. Specialized research racks for physical sciences experiments on the ISS are designed to hold several modules. Each module contains one or more experiments, and in some cases the equipment can be shared. Large projects, such as the-low temperature facility, will be installed in special carriers mounted on the outside of the ISS. Overall, the cuts made in the NASA/ISS research capability budget since Rev. F were absorbed primarily by the physical sciences research program, whose budget went from $980 million to $576 million, a 41 percent reduction.2 This reduction resulted in the cancellation (or deselection) of 26 of 77 flight experiments, a 34 percent reduction. Most of the deselected experiments, although not yet under construction, were chosen for deletion because the necessary facilities would require near-term expenditures. Scientific merit was not a criterion. In addition, significant reductions in the scope of the remaining experiments retained have been imposed. In large part the physical science experiments are designed for remote operation and require relatively little crew intervention, so they could in theory be carried out with the smaller three-person crew. However, just the time needed to load an experiment, let alone intervene in an ongoing experiment, might exceed the allotted U.S. crew time (7.5 hours/week). NASA also is planning fewer shuttle flights to the ISS; four per year were recommended in the Young report (IMCE, 2001), greatly constraining the ability to transport materials to be used in the experiments. Finally, the uncertainty surrounding the budget and funding levels is having a negative impact on the scientific community, as principle investigator (PI) funding for scheduled flight experiments is reduced. Given these uncertainties, PIs may seek opportunities elsewhere, thereby jeopardizing the future of ISS science. MATERIALS SCIENCE Program Description The overall goal of the OBPR materials science program is to use microgravity to establish and improve the quantitative and predictive relationships among the processing, structures, and properties of materials used for making products. Materials are inherent in all branches of engineering and have influenced social change profoundly over the course of history. Because gravity plays a critical role in materials formation, it is necessary to understand and control the effect of gravity on the processes used to produce materials, and also to resolve fundamental scientific questions about materials phenomena by 1   The cell biology research carried out in the biotechnology program is discussed in other sections of this report. Protein crystal growth, also part of the biotechnology program, is not among the subdisciplines covered in this report, although it has been reviewed recently by the NRC (2000a). 2   From FY 01 budget to Administration’s FY 03 proposed budget.

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences testing them in an environment free of contamination by fluid convection, sedimentation, and hydrostatic pressure. In particular, experiments in this program have been directed at producing benchmark data sets or testing fundamental theories. Examples of OBPR-funded research in materials science include studies of the role of liquid convection in crystal growth, including its influence on impurities and crystal perfection; isothermal dendritic growth; directional solidification; gravitational effects on distortion during sintering; the accurate measurement of thermophysical properties needed for the computer-aided modeling of manufacturing processes; the formation of metallic glasses (amorphous metals); and the exploration of new and innovative ways to process materials (Sekerka, 2001a). To date, fundamental knowledge of the role of convection in crystal growth has been applied to the production of melt-grown silicon crystals (as a source of substrates for integrated circuits), with an increase in yield approaching two orders of magnitude (Sekerka, 2001b). Scientific research on isothermal dendritic growth in microgravity has established a basis for assessing the validity of competing theories of dendrite growth. Liquid-phase sintering studies in microgravity are expected to provide design parameters for the low-cost fabrication of parts, for example, automobile connecting rods. The quality of the materials science research funded through the physical sciences program is uniformly high. This is reflected, for example, in the scientific stature of current and previous NASA principal investigators (PIs).3 Impact of ISS Changes In the Rev. E (June 1999) Assembly Sequence and Research Outfitting design, the dedicated Materials Science Research Rack 1 (MSRR1) was scheduled for delivery to the ISS in February 2003. In Rev. E, the second and third dedicated materials science research racks (MSRR2 and MSRR3) were deferred to 2005 or later. In Rev. F (August 2000), MSRR1 was scheduled for September 2004, a slippage of 19 months. In Rev. F, MSRR2 and MSRR3 were deferred to 2006 or later. Subsequently, in the Core Complete design, MSRR1 is scheduled for January 2005 with an attendant slippage of 4 months, while MSRR2 and MSRR3 are canceled. The microgravity research program selected 26 materials science flight investigations for execution through 2008 (Wargo, 2002). Eighteen of these flight investigations were to utilize MSRR1, MSRR2, or MSRR3; three investigations were to be carried out in the Microgravity Science Glovebox (MSG) facility, two investigations in the European Electromagnetic Levitation (EML) facility, two in the Japanese Electrostatic Levitation (ESL) facility, and one in the French DECLIC apparatus. In terms of materials science, the reduction in the NASA ISS research capability budget translated into the elimination of MSSR2 and MSSR3, with attendant cancellation of equipment. The one remaining piece of NASA-provided equipment for MSRR1 is the Quench Module Insert, which will be inserted into the Materials Science Laboratory planned to be built by the European Space Agency (ESA). NASA’s rationale for the elimination of MSRR2, MSRR3, and 10 experimental modules (Robey, 2001) is that substantial funding is associated with these facilities, coupled with the fact that each facility was scheduled far enough into the future to avoid the lay-off of current employees. In addition, the resource analysis from the ISS program office at the Johnson Spaceflight Center (JSC) indicated that activities in the materials science research racks were more crew-intensive than those in the other physical sciences flight research programs (Trinh, 2002a). NASA reports that as of April 10, 2002, 12 flight investigations remained in the OBPR materials science program (Wargo, 2002) (see Appendix A). Nevertheless, only part of the original proposed scope of work can be conducted in each investigation. This limit on scope will adversely affect the level of meaningful research that can be performed in materials science. Seven flight investigations will use the 3   Seven are members of the National Academy of Engineering, two are members of the National Academy of Sciences, and five are fellows of the Metals, Minerals, and Materials Society.

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences MSRR1 facility, three will be performed in the MSG facility, and two will make use of the EML facility to be fabricated by the ESA and installed in the European Columbus Orbital Facility (COF). The 14 flight investigations that have been eliminated from the materials science program are listed alphabetically in Table 2.1. These investigations were designed to enhance the materials processing science base, thereby allowing improvements in metal casting technology; process modeling of casting and welding; design of alloys for automotive, aerospace, and computer applications; fabrication of new microporous materials for application in detergents and petroleum cracking; fabrication of alloys compatible with high-temperature applications; the manufacture of improved electro-optical materials; and the commercial production of bulk metallic glasses. As shown in Appendix A, seven flight investigations in materials science are planned for MSRR1 over the time frame 2005-2008. Of the three flight investigations to be carried out in the MSG facility, one is scheduled for 2002 and the remaining two for 2007. The two flight investigations in the EML facility are scheduled for 2005. The severe reduction in the scope and number of flight investigations in materials science from 26 to 12 (54 percent) comes from the elimination of MSRR2 with its complement of experiment modules and the elimination of planned experiment modules from MSRR1. MSRR3 was to have accommodated modules for future experiments, international hardware, and equipment for new initiatives and multidisiciplinary utilization (Robey, 2001). Consideration is being given to restoring the two investigations by Beckermann and one each by Koss and Glicksman (Wargo, 2002). A funding wedge (a research reserve mandated by OBPR to enforce prioritization of OBPR science) has been set aside in the research budget of the OBPR programs to cover the cost of experiments identified as having a high priority. It may also be possible to reinstate Trivedi’s investigation by using the French DECLIC apparatus through a collaborative agreement. With the reorientation of the research to emphasize the use of specific facilities across disciplines, it may be possible to use the Combustion Integrated Rack (CIR), should it be built, for a limited number of materials science experiments. The overall impact of restructuring and downsizing the ISS research program in materials science is that much of the basic science integral to key areas of materials processing is deferred indefinitely. In particular, all U.S. space research on the ISS involving thermophysical property measurements, dendritic solidification, and the evolution of microstructure on a local scale using transparent model systems—research that is important to both space- and ground-based manufacturing—will be terminated. There will also be a significant reduction in the amount of research on semiconductor crystal growth, optoelectronic materials, and microstructure development and pattern formation in metal casting. No new starts in nascent areas (such as biomaterials) will be possible, unless these areas are given a higher priority. With the restructured research program for the ISS, it becomes difficult to claim that materials scientists will have a state-of-the-art laboratory for pursuing cutting-edge research in materials processing in a microgravity environment. In its phase I report (NRC, 2001), the task group cautioned that investigator readiness is beginning to deteriorate, and that it will continue to do so as the date of completion for the ISS slips—an opinion shared widely in the ISS user community (Sekerka, 2001b; Fettman, 2001; Katovich, 2001). The restructuring and downsizing of the materials science component of the ISS research program will have a negative impact on PI readiness in this discipline. Only one flight experiment in materials science is scheduled prior to 2005. Factors Limiting Utilization of the ISS A major factor limiting utilization of the ISS by the materials science community is the elimination of MSRR2 and the experiment modules associated with nine experiments in MSRR1 and MSRR2 collectively (Robey, 2001). The only remaining experimental capability is that associated with the Low Gradient Furnace (LGF) and the Quench Module Insert (QMI) in the Materials Science Laboratory (MSL). This has imposed a limit of seven experiments in MSRR1 (Appendix A) but it

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences TABLE 2.1 Flight Investigations Eliminated in the Core Complete ISS—Materials Science Investigation Principal Investigator Affiliation Self diffusion in liquid elements R.M. Banish University of Alabama, Huntsville Thermophysical property measurements: Te-based II-VI semiconductor compounds R.M. Banish University of Alabama, Huntsville Equiaxed dendritic solidification experiment C. Beckermann University of Iowa Dendritic alloy solidification experiment C. Beckermann University of Iowa Fundamental study of crystal growth in microporous materials P. Dutta Ohio State University Evolution of local microstructures: spatial instabilities of coarsening clusters M. Glicksman Rensselaer Polytechnic Institute Physical properties and processing of undercooled metallic glass-forming liquids W.L. Johnson California Institute of Technology Transient dendritic solidification experiment M. Koss College of the Holy Cross Diffusion processes in molten semiconductors D.H. Matthiesen Case Western Reserve University Space- and ground-based crystal growth using a baffle A. Ostrogorsky University of Alabama, Huntsville Dynamical selection of three-dimensional interfacial patterns in directional solidification R. Trivedi Iowa State University Crystal growth of ZnSe and related ternary compound semiconductors by vapor transport C.H. Su Marshall Space Flight Center Microgravity studies of liquid-liquid phase transitions in undercooled alumina-yttria melts R. Weber Containerless Research, Inc. Defect formation during melt growth of electro-optical single crystals A.F. Witt Massachusetts Institute of Technology   SOURCE: Wargo (2002). probably represents optimal restructuring for the ISS materials science program given the overall budget cuts in ISS research. This drastic curtailment is having a negative effect on the materials community, since the restructured ISS is not able to accommodate current and future PIs of approved proposals. In the absence of a modern laboratory for cutting-edge materials research in an extraterrestrial environment, the ISS will fail to fulfill one of its primary objectives in the materials research field. In turn, materials researchers will have little or no alternative but to abandon NASA and fields of study dependent on flight opportunities and pursue careers elsewhere. Note also that NASA’s Commercial Furnace Module cannot be used for those materials science experiments currently selected, as its capabilities do not satisfy space and power requirements. All the experiments in the MSRR1 are fully automated and can be run from the ground. Sample exchange is accomplished manually and is projected to take 1-1.5 hours per exchange (Wargo, 2002). Similarly, in the MSG, the experiments are semiautomated once the samples are in the facility and instructions are preprogrammed into the apparatus. The EML will be run from the ground, but sample exchange, pumping, and

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences the replacement of gas bottles will be manual, with a projected time of 1-1.5 hours per event. Thus, while the materials research experiments require modest crew intervention, the reduction in crew size from seven (or six) to three may impact the program adversely. With the U.S. allotment of 7.5 hours/week, insufficient time will be available for a crew of three to load or exchange experiments. Maximizing ISS Research Potential The most effective option for maximizing the remaining research potential of the ISS in materials science would be to make resources available for the development of experimental modules for MSRR1. The projected final cost of MSSR1 ($124 million) is about 0.5 percent of the $31 billion projected cost to complete the construction of the ISS (IMCE, 2001). MSRR1 was designed to accommodate PIs who have entered the program over the last 5 years, as well as future PIs. In this context, it will be critical to the future of the materials science program on the ISS to establish priorities. As noted in the preceding section, to increase ISS research potential in materials science, allocation of resources to restore some or all of the experimental modules is essential. These modules can be accommodated in MSRR1. It is important to appreciate that space is available in MSRR1. The MSL within MSRR1 leaves room for several experimental modules. Reinstating some (or all) of the experimental modules in the materials science program would take advantage of dead (wasted) space in the one dedicated research rack. A limited class of materials science research, that is, experiments compatible with low power and small volume, could be executed on the EXPRESS rack. For example, the two investigations proposed by Banish (see Table 2.1) might be compatible if sufficient power is available. However, no money has been allocated to build the equipment required for these investigations. While in principle the utilization of the ISS might be increased by speeding up the preparation of investigations for flight, the materials science program is “too ready,” with PIs awaiting a launch date. The rate-limiting element is access to capability (research facilities), which is tied to the launch schedule, upmass (and downmass), and budget. COMBUSTION SCIENCE AND FIRE SAFETY Program Description NASA’s highest-priority goal for the Human Exploration and Development of Space (HEDS) program is safety. One of the most feared, potentially catastrophic safety hazards in spacecraft is fire. At least six prefire, on-orbit incidents have occurred involving the space shuttle, and two serious fires erupted during the Russian space station program. In support of these concerns, a panel of combustion experts (Law, 2001) has stated as follows: We can say with near-certainty that the probability of the initiation of an accidental fire event during the lifetime of ISS is unity—whether the fire transitions into a serious problem or not will depend on our collective knowledge of low-gravity fire prevention, detection, and suppression. NASA’s ongoing research program has made encouraging progress to minimize the frequency and consequences of such an event, but future progress—both for ISS and exploration—depends critically on the use of the Combustion Facility as planned for the ISS. Fire safety can be implemented at three stages: fire prevention, fire detection, and fire suppression. Recommended methods and procedures developed for fire safety under normal-gravity environments do not necessarily apply to microgravity environments since gravity plays a dominant and frequently controlling role during combustion on Earth. Heat released in flames on Earth leads to a rapid and dramatic (factor of seven) decrease in density and creation of buoyancy-induced flows. Virtual

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences elimination of buoyancy in microgravity allows other mechanisms to control flame characteristics (Ross, 2001). Not only can fire safety issues be examined on the ISS, but microgravity also provides opportunities to measure phenomena otherwise masked or complicated by gravitational forces. The likelihood of success and of benefits for ground-based energy production is sufficiently great that in 1999 a NASA advisory group for combustion science (Law, 1999) proposed a major, focused activity in the flight research program that would obtain fundamental data and practical information for industrial applications. Clearly, funding issues now preclude such an expansion, but the interest and need for such studies remain. NASA has sought to encourage research in the microgravity combustion program that is relevant to energy use, global warming, air pollution, and industrial manufacturing. Combustion research issues that would be pursued on the ISS by investigators now in the ground and flight program include flammability limits and flame propagation of various solid and liquid fuels under microgravity conditions, combustion around single fuel droplets and internal droplet circulation, radiative quenching in flames, the character of soot/particle formation in microgravity, and the transition between smoldering fires and flames. Collectively, these fundamental investigations would contribute to spacecraft and building fire safety, reduced pollutant formation, increased engine efficiency, and education. Numerous highly distinguished investigators have been attracted to this program.4 Impact of ISS Changes The principal facility for combustion research on the ISS is the CIR. The unique software structure of the CIR (which has won federal, NASA, and private sector awards) was designed to minimize the need for crew. Its design enables tool-free, rapid change-out of PI-specific modular components (windows, diagnostics, and experimental hardware). The storage and processing capabilities are 100 times greater than those of an EXPRESS rack, which minimizes communication needs and maximizes flexibility in operations. The CIR is planned for construction within an international standard payload rack containing its own isolation, avionics, power, software, and environmental subsystems. In addition, it includes an optics bench, a combustion chamber for low- and high-pressure operation, fuel and oxidizer management, exhaust treatment, and related diagnostics. This multiuser facility is uniquely capable of providing a reusable on-orbit capability for combustion science research on the ISS. Additional details of the CIR and its capabilities are provided by O’Malley and Weiland (2001). The CIR will provide 90 percent of the flight hardware needed to perform most of the microgravity combustion experiments. (Some early experiments will be performed in the MSG.) The remaining hardware will be PI-specific and will be provided by the PI hardware development teams. This PI-specific hardware will be launched separately from the CIR and installed into the CIR in orbit and may be shared with other PIs. In Rev. F, the CIR was to be housed in the Fluids and Combustion Facility (FCF) (NASA, 2002a), which contained the CIR and the Fluids Integrated Rack (FIR), together with the Shared Accommodations Rack (SAR). The SAR was to house common capabilities, including power control and distribution, environmental controls, command and data management, communications, and stowage. In addition to the CIR/FCF, the MSG was, and still is, available for limited combustion-related experiments. In the initial description of the ISS Core Complete design, the CIR and the SAR were eliminated, which would have prevented further research on fire safety on the ISS. The CIR facility was temporarily added back into the ISS plan, following a substantial and rapid response to NASA headquarters and to Congress by the combustion and industrial communities (U.S. Sections, Combustion Institute, letter to D. Goldin dated March 29, 2001; also see, for example, Syed, 2001; Pearlman, 2001; T’ien, 2001; Edelman, 2001; Egolfopoulos, 2001; Schowengerdt, 2001; and Bellan, 2001). With the elimination of the SAR, all operational components must be self-contained within the CIR, and the repackaged CIR has limited 4   Four are members of the National Academy of Engineering, 19 are fellows of scientific and engineering societies, and 2 are among the most highly cited 100 engineers according to the ISI (Voorhees, 2002).

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences optical and diagnostic access. In addition, numerous advanced diagnostics have been eliminated owing to insufficient space without the SAR (D.L. Urban, personal communication, 2002). Despite its temporary reinstatement, the CIR is still in jeopardy as a result of continuing budgetary concerns. Without it, six of the ten combustion investigations on spacecraft fire safety, combustion fundamentals, and pollutant formation (see Appendix B) cannot be performed. The ISS resources reduced in the Core Complete design are crew time, upmass, and stowage volumes, all key to the combustion program. Assessing the impact of these reductions on the CIR experiments is difficult, since a prioritization for use of resources was not provided by NASA management. Nevertheless, as described in the following paragraphs, the reduction in station size and in the number of shuttle flights will significantly decrease the resources available for combustion science on the ISS. Even at the completion of Core Complete, crew time available for experiments will be significantly constrained, with only three crew members present on the ISS. This constraint will have an impact on planned combustion research but should not cripple the research effort, as the CIR was designed to minimize the need for crew interactions. Originally, NASA estimated that a minimum of 100 hours of crew time per year would be required to support experiments in the CIR. With Core Complete, the allocated time has been reduced to about 30 hours per year. This reduction is accommodated by decreasing the number of scheduled runs for each PI. Since time is typically consumed in calibration and demonstration of technique, the 70 percent reduction in crew time is expected to result in greater than 70 percent reduction in the quantity of science returned. Communication rates are limited to the existing maximum ISS pipeline bandwidth of 50 megabits per second. Since bandwidths sufficient for real-time control (3 megabits per second) cannot be dedicated to an experiment, combustion investigations will utilize a low-resolution video transmitted with a time delay of many seconds or minutes followed by transmission of a set of high-resolution still pictures in the hours following an experiment. Dedicated communications were planned in an earlier ISS configuration. Without this capability (and in the absence of compensatory crew time) and despite careful preplanning of experiments, it will be challenging to make effective use of the limited fuel and oxidizer samples and maximize scientific return. The smaller ISS and reduction of the shuttle flights to four per year have also necessitated reductions in the stowage and upmass allocated per experiment. Typical material required for an experiment includes gas cylinders, fuel samples, extra cameras, and redundant (back-up) equipment. To accommodate facility changes in Core Complete, stowage per experiment has been reduced from about 0.2 cubic meters to an estimated 0.1 cubic meters. The result is that each set of experiments has been replanned and will be constrained to fewer tests over a smaller range of conditions, thus reducing their scientific value. Given that the first set of experiments are performed for calibration and demonstration of technique and that some of the stowage volume is required for hardware, the decrease by a factor of two in allocated stowage will lead to a greater than twofold decrease in returned scientific results. Solid fuel experiments have been reduced by as much as a factor of four. Hence, the combustible (fire safety) characteristics of some materials cannot be evaluated, and there will be a smaller range of conditions examined for other fuels. In addition to reductions in ISS facilities, budgets for ground-based activities have been decreased. All PI projects were reduced by 5 percent in FY 01, and all ground-based and selected flight projects are being reduced by another 10 percent or more in FY 02. Furthermore, the employment of summer students at NASA sites has been reduced dramatically (by 80 percent); this program is recognized as having provided excellent training experience for the next generation of the nation’s scientists and engineers. In addition, the selection of new combustion experiments that would fly after 2008 has been curtailed due to the lack of funds for flight reviews. Of the experiments already selected for flight on the ISS, three have been eliminated in the Core Complete plan. These experiments were originally planned as ISS glove box investigations. The eliminated projects are shown in Table 2.2.

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences TABLE 2.2 Flight Investigations Eliminated in the Core Complete ISS—Combustion Science Investigation Principal Investigator Affiliation Low stretch diffusion flames over solid fuels S. Olson NASA Glenn Research Center Surface smoldering spread and evolved products T. Kashiwagi National Institute of Standards and Technology Front interaction with vortex experiment P. Ronney University of Southern California Together these glove box investigations were to have provided supplemental information in support of other flight- or ground-based investigations on fire safety and pollutant formation. The planned list of ISS experiments in combustion science that will be flown through 2006 is given in Appendix B. The CIR experiments through 2005 include only combustion experiments on fuel droplets. In 2006, alternative CIR inserts will be provided for examination of flames with solid and gaseous fuels.5 Except for the glove box investigations cited above, NASA has not eliminated any other combustion investigations, in the hope of maximizing both scientific return and community involvement. Instead, each of the experiments that will be flown has new limitations to the range of experimental conditions and the number of materials that can be evaluated. These limitations are an important and undesirable constraint on the fire safety investigations. Nevertheless, if the CIR is flown on the ISS, if adequate crew time is available, and if sufficient upmass is provided, benefits are anticipated to accrue in the areas of spacecraft fire safety, education, engine efficiencies, and pollutant emission. Factors Limiting Utilization of the ISS The CIR is a critical component for the majority of the combustion experiments planned through 2010, yet its existence on the ISS is threatened by budgetary concerns. Without this facility, the ISS cannot be effectively utilized for a program of combustion research. The EXPRESS racks cannot be easily modified into a substitute CIR owing to substantial requirements for flow control, diagnostics, automated exhaust treatment, safety, and high data acquisition and data storage. Assuming that the CIR is available, other factors limiting the use of the ISS for research in combustion science include crew time, stowage volume, upmass, and bandwidth for communications. Initial (Rev. F) estimates (D.L. Urban, personal communication, 2002) of crew time required to support combustion research were approximately 100 hours per year. Crew time that will be available for combustion research has now been reduced to about 30 hours per year. Desired stowage volume for several of the combustion experiments exceeds the imposed allocation of 0.1 cubic meter for consumables and other related materials by at least a factor of two. Enhancements of international collaborations have the potential to increase the value of the scientific research in this area, and limited interactions already exist. In combustion research, collaborations include the European development of a high-pressure chamber to be placed into the CIR for European-sponsored experiments of combustion processes at high pressure, as well as construction of a disk laser by the Europeans to use as a high-powered light source (diagnostic) in the CIR during combustion experiments. In addition, NASA has recently initiated a coordinated International Announcement of Opportunities, similar to a NASA Research Announcement, but only the Japanese have 5   As of the final printing of this report, full funding is available for the development of the insert for solid fuels, and funding is being sought for the gaseous fuel insert.

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences acted by funding some recent proposals. Generally, the coordination of international activities is challenging due to cumbersome negotiations, but it is expected that science will benefit through increased international interactions and sharing of facilities, and perhaps co-planning of experiments and/or inserts for the CIR. Maximizing ISS Research Potential A strong ground-based research program is the most important factor for maximizing the potential of the ISS for scientific research in general, including combustion research. The ground-based efforts create a critical mass of scientists and engineers who identify the creative, world-class experiments for flight investigations. This pool of scientists also reviews, examines, and carefully revises experiments proposed by individual PIs to maximize the potential benefit and impact of each experiment. At present, NASA’s microgravity program in combustion science is attracting most of the leading combustion researchers in the United States and their students. Continuation of the ground-based program will maintain strong interest in related science issues and help to attract students to the field. Perhaps the most important constraint of Core Complete on combustion research comes from the limitation on consumables. Relaxation of newly imposed volumetric and weight limitations on consumables (i.e., the combustible materials) would have a direct impact on the quantity and quality of science that can be performed once experimental hardware is in space. This issue is particularly important for fire safety investigations, in which flammability limits for a range of materials need to be determined. If materials are not flown, then their combustible characteristics cannot be determined. Thus, relaxing upmass constraints would have a direct benefit in reducing fire safety hazards for future manned flights. The constraints of crew time and training could be mitigated partially by allocating higher-bandwidth communications to the experiments. Safety issues, occasional unexpected events, and event times measured in fractions of a second call for real-time monitoring of combustion experiments. High data acquisition and storage rates are provided within the CIR to collect data for postprocessing and for downloading in the hours following an experiment. Active monitoring is desired during each experiment in case unusual or unanticipated events occur. At present, it is expected that support from the crew and time for appropriate training will be minimal. Hence, it must be presumed that the outcome of an experiment can be well enough known that the sampling rates, the duration of the experiment, the control of oxidizer or fuel flows, etc. can be preprogrammed via software. Time scales can vary dramatically in combustion experiments, and predictive models or ground-based experiments provide only a guide to ideal sampling conditions for optimum scientific return. Bandwidths of 2-3.5 megabits per second dedicated to the combustion investigations at the time of the experiments could enable (compressed) real-time video monitoring from the ground, with a ground-based scientist then able to intervene and adjust the experiments as appropriate. Increased science return would be anticipated, due to more effective use of the equipment and consumables. However, crew time would still be required to change fuel and oxidizer samples or make facility changes. Another possibility, perhaps unique to combustion research, for increasing the utility of the ISS is to investigate effects of partial gravity (0 to 1 g) on flame spread rates and flammability. The centrifuge module would enable simulation of partial gravity conditions for extended times; the longest test time available for examination of fire safety issues on Earth through aircraft-based tests approaches 1 minute for partial gravity (0.6 g) conditions and much shorter for lower gravity levels. A separate rack for such studies would have to be designed and built to perform such investigations, and the possible effect of coriolis forces would have to be addressed. It should be noted that such an approach is not part of existing NASA plans; however, the importance of the proposed studies is based on the nonlinear dependencies between phenomena driving combustion. As gravity (and buoyancy) increases above microgravity conditions, natural convection adds fresh air to the flame and thus increases flame spread rates; but at higher gravity levels, the higher levels of buoyancy-driven air cool and dilute the combustion

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences products, thus slowing the transfer of heat to the flame and reducing resultant flame propagation rates. It has been shown that flame spread and flammability characteristics are most adverse under partial gravity conditions, such as those on the Moon or Mars (Sacksteder and T’ien, 1994). Hence, it is strongly recommended by the task group that the centrifuge, if flown, be utilized also for fire safety investigations in anticipation of human flights to Mars. FLUID PHYSICS Program Description The goal of the OBPR fluid physics program is to comprehend the fundamental physical phenomena underlying flows observed in nature and to aid the space program in its effort to develop new technologies or to adapt existing technologies to space applications. The fluid physics program encompasses five major research areas: interfacial phenomena, biological fluid dynamics, dynamics and instabilities, complex fluids, and multiphase flows and phase change. Research on interfacial phenomena includes studies directed at understanding capillary phenomena and the dynamics of fluid-fluid and fluid-solid interfaces. Biological fluid dynamics focuses on the underlying fluid physics and transport phenomena in biological and physiological systems. The study of dynamics and instabilities encompasses research topics ranging from the fluid mechanics of star formation and Earth’s interior to the dynamics of electrically charged fluids. Complex fluids currently under investigation include fluids as diverse as colloids, foams, and granular aggregates, with applications ranging from sensors to smart materials. Multiphase flows and phase change involve investigations in two-phase flows, such as gas-liquid systems, in which gravity has a controlling influence on the flows owing to the large density difference between the phases. The research in many of these areas is relevant to the HEDS program. For example, multiphase fluid flow experiments performed in microgravity are important for applications such as spacecraft thermal management, environment control, human life support, and advanced power and propulsion systems (NRC, 1995). It is worth noting here that the quality of the investigators attracted by the NASA fluids program has been very high.6 Impact of ISS Changes The facilities planned in Rev. F for the ISS for use in fluid physics research were the Fluids Integrated Rack, the Microgravity Sciences Glovebox, the Shared Accommodations Rack, and an EXPRESS rack. A total of 32 experiments had been selected for flight using these facilities through 2008. The recent cut in NASA’s OPBR budget for ISS research was absorbed in large part by the physical sciences research program, and a significant part of that was in fluid physics, where the SAR was eliminated and several modules were lost. In fluid physics, NASA cut a number of experiments still in the development stage, resulting in the elimination of nine experiments slated to fly in the 2003-2005 time frame. The remaining 23 experiments are now expected to fly in 2005-2008 if funds become available for the development of the experimental modules. Further budget cuts being considered in this program could either eliminate some of these selected experiments or greatly reduce future experiments in 2008 and onward. For example, 7 of the existing 23 experiments counted in the fluid physics total are still 6   As evidenced by the fact that of the 110 PIs in the program in FY 01, 8 were members of the National Academy of Engineering, 4 were members of the National Academy of Sciences, 37 were fellows of the American Physical Society, 12 were fellows of the American Institute of Aeronautics and Astronautics, and 5 were fellows of the American Society of Mechanical Engineers (Voorhees, 2002).

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences uncertain because their funding depends on the budget wedge—a research reserve mandated by OBPR in order to enforce prioritization of OBPR science (Trinh, 2002b). The principal reduction in fluid physics capability on the ISS is that due to the elimination of the SAR, a resource to have been shared between fluid physics and combustion research. According to information provided by NASA, experiments were selected for elimination based on their proximity to flight (thus reducing near-term budgets) rather than on scientific priorities. It is hard to determine the exact number of experiments eliminated by the loss of this facility, because several of the proposed experiments might be accommodated in the FIR or the MSG or in facilities provided by international partners. The loss of this facility affects the number rather than the type of experiments that can be performed aboard the ISS. The nine eliminated experiments are shown in Table 2.3. The experimental modules currently planned for flight research are the Light Microscope Module, the Granular Flow Module, and the Ultraviolet-Visible-Infrared Spectrophotometer (UVIS), all of which are intended for use in the FIR. Two instruments for fluid physics research are also being planned for use in facilities provided by the international partners, the Fluid Science Laboratory (FSL) and DECLIC. The FSL is a multiuser research facility dedicated to investigations in fluid physics under microgravity conditions. It can be operated in fully automatic or semiautomatic mode on the station by the flight crew or remotely controlled from ground in the so-called telescience mode. DECLIC is dedicated to the physics of transparent media in general and to model material sciences and near-critical and supercritical research in particular. The Pool Boiling Module is no longer planned. The racks are outfitted to be operated remotely from the ground. The crew is needed primarily for sample change-out and instrument repair as needed. According to NASA the U.S. fluid physics research currently remaining on the schedule (listed in Appendix C), while considered to be of very high quality, was retained principally because these experiments were to be flown at a late date, and therefore the cost for module development could be deferred. Whether there will be resources in the future for module development is critical for the success of the fluid physics program. (For example, the CIR was initially cut, but it has been restored by Congress. The restoration of this facility comes with a potentially significant future cost to the physical sciences research program, because the funding provided was insufficient to complete the facility and the remaining cost may be borne by the research program in future years.) While most of the fluid physics research experiments are designed to be operated by ground personnel and therefore require only modest crew intervention, the reduction of the crew from seven (or six) to three may nevertheless adversely impact the program. With a crew of only three, so little time is available (given the U.S. allotment of 7.5 hours/week) that simply loading or exchanging experiments can consume all of it. Compared with some other disciplines, however, the fluid physics program is well positioned to operate on the Core Complete ISS, although suboptimally in terms of numbers of experiments that can be performed. The loss of the SAR and associated resources for module development limits the type and number of experiments that can be performed. The SAR could accommodate a greater number and variety of experiments than the FIR and MSG. Completing the SAR as originally planned would greatly enhance the fluid physics research program. The principal impact of the budget cuts and restructuring of the ISS on PI readiness has been a reduction in the number of new investigations funded in the latest call for proposals and an across-the-board 15 percent cut in all funded investigations. There is still an active complement of researchers in the program, but there is growing concern in the fluids community that the program is in jeopardy. If this concern is not addressed and the funding picture deteriorates further, many excellent PIs may leave the program.

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences TABLE 2.3 Experiments Eliminated in the Core Complete ISS—Fluid Physics Investigation Principal Investigator Affiliation Microscale Hydrodynamics Near Moving Contact Lines (fundamentals of wetting and spreading of fluids) Steve Garoff Carnegie Mellon University Passive and Active Stabilization of Liquid Bridges in Low Gravity (important for drop dynamics, wetting, and growth of molten materials) Phil Marston Washington State University Microgravity Experiments to Evaluate Electrostatic Forces in Controlling Cohesion and Adhesion of Granular Materials (applications in the processing and transport of granular particulates, e.g., pharmaceuticals) John Marshall NASA Ames Diffusing Light Photography of Containerless Ripple Turbulence (fundamentals of two-dimensional turbulent fluid flows) Seth Putterman University of California, Los Angeles Acoustic Study of Critical Phenomena in Microgravity (fundamentals of material phase transitions) Mike Moldover NIST Using Surfactants to Control Bubble Growth Coalescence in Nucleate Pool Boiling (boiling is a widespread natural and industrial process used, for example, in steam production in power plants) Kate Stebe Johns Hopkins University Structure and Dynamics of Freely Suspended Liquid Crystals (containerless processing of liquid crystals, which are used in flat panel displays, for example) Noel Clark University of Colorado Gradient Driven Fluctuations (fundamental fluid physics) David Cannell University of California, Santa Barbara Investigations of Mechanisms Associated with Nucleate Boiling under Microgravity Conditions (boiling is a widespread natural and industrial process used, for example, in steam production in power plants) Vijay Dhir University of California, Los Angeles Factors Limiting Utilization of the ISS Two main factors keep the fluid physics community from maximizing the remaining research potential of the ISS. The first is the development of experiment modules to be used in the facilities. These modules are tailored to a specific set of requirements and can be used for several related investigations (e.g., colloidal physics, granular flow research). A broad range of research areas could be covered with use of the SAR, as discussed above. Furthermore, had development of the SAR continued, it would have provided advanced data handling capabilities, science accommodations, and upgrade possibilities that could significantly increase science utilization on the ISS for fluid physics and combustion science. Since the SAR design was to be patterned after that of the FIR, its development cost is much less than either the FIR or CIR, which are first-unit builds. The second main factor limiting the utilization of the ISS is the research and technology infrastructure (number and level of PIs supported). Only a few areas of research are being pursued on the

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences ISS. This is having a very negative impact on the community at large, as many investigators are being turned away from ISS research because there are not enough resources to accommodate their areas of study. As mentioned before, many of the flight-selected experiments require experiment module development, and resources for that development must be assured, while at the same time not jeopardizing future experiments. Maximizing ISS Research Potential As noted above, the principal factor limiting the fluid physics community from maximizing the research potential of the ISS is resources for module development. The expected crew utilization, the availability of power, the data up-link capacity, etc. are adequate to carry out the currently selected suite of experiments. Restoring the SAR to the ISS would greatly expand the available experimental platform and allow a more vigorous program. Stable funding for module development and for ground-based research from which future flight experiments will be selected is necessary. The fluid physics program offers a tremendous scientific return for a relatively modest investment. FUNDAMENTAL PHYSICS Program Description There are three principal research areas in the fundamental physics microgravity program: gravitational and relativistic physics, laser cooling and atomic physics, and low-temperature and condensed matter physics. The fundamental physics program began about 15 years ago as an outgrowth of the low-temperature part of the fluid physics program. The original emphasis was on liquid helium critical point experiments; since the early 1990s, the program has grown considerably and now includes laser cooling and trapping of atoms, high-energy physics (cosmic ray studies), gravitational relativistic physics (tests of the equivalence principle), and atomic clock experiments. It can be fairly stated that the overall quality of research funded through this program has been very high. Many of the most highly regarded scientists in the country working in these fields have participated in the program, including 6 Nobel laureates, 9 members of the National Academy of Sciences, and 25 fellows of the American Physical Society (Voorhees, 2002). The basic thrust of the fundamental physics program has been the investigation of phenomena that are not accessible, or only partially accessible, on Earth, as a consequence of either gravity or the atmosphere. Most of the experiments in this program depend on the absence of gravity to enable measurements not possible on Earth. One such area is the preparation and study of unique samples, such as a uniform fluid free from gravity-induced density gradients. This uniformity is of crucial importance for the study of critical phenomena. An early successful experiment in this area was the Lambda Point Experiment that was flown on the space shuttle in October 1992. Heat capacity data were obtained approaching a few nanokelvin of the lambda point (NRC, 1995). Similarly, while then considered as part of the fluid physics program, a space shuttle study of the critical point (Tc) of xenon by Berg, Moldover, and Zimmerli (1999) obtained viscosity data two orders of magnitude closer to the critical point than was possible on Earth and found an unexpected frequency-dependence close to Tc, signaling the onset of viscoelastic behavior. Among the critical point studies planned for the ISS program are studies of the equation of state of helium, accurate tests of scaling hypotheses and crossover models, finite-size scaling effects, and critical phenomena in out-of-equilibrium systems. A second research area that is enabled by the microgravity environment is high-resolution laser cooling and atomic clock studies. The anticipated development of highly accurate clocks in space would be of major benefit for navigation and guidance systems. Because gravity is absent, laser-cooled beams of atoms can interact with radiation fields for extended times, providing extremely accurate measurements

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences of frequency. This capability will be exploited both to test very-high-precision atomic clocks and to carry out highly sensitive tests of Einstein’s equivalence principle and of other predictions of relativity theory. The satellite test of the equivalence principle (STEP) experiment, in which Galileo’s famous Pisa experiment will be repeated in the microgravity environment, will advance by five orders of magnitude the precision with which the equivalence principle has been tested (Ashby, 2002). Additional tests of relativity will be conducted with a new superconducting microwave oscillator (SUMO), which will also provide a calibration for atomic clocks. One class of experiments requires use of the ISS not for the absence of gravity, but rather for the absence of the atmosphere. Antiprotons are elementary particles that are strongly absorbed by the atmosphere. The Alpha Magnetic Spectrometer (AMS) experiment will measure the flux of antiprotons impinging on Earth, providing a sensitive test of some current cosmological theories that predict a proton-antiproton asymmetry. Impact of ISS Changes Under the Rev. F model, one major fundamental physics facility was planned for the fundamental physics program on the ISS, and this facility has been retained under the Core Complete model. The Low Temperature Microgravity Physics Experiments Facility (LTMPEF)7 will be mounted on the outside of the ISS. Its liquid helium cryostat can simultaneously accommodate two experiments. While the LTMPEF will support the planned experiments in low-temperature physics, those investigations classed as laser cooling and atomic physics experiments will be attached at a second external site on the ISS. The latter experiments are expected to utilize experiment-unique hardware and will not be housed in a common facility. In addition, the large instrument for the AMS experiment8 requires its own external attachment site. In 2001 it was decided to eliminate the LTMPEF, although the decision was subsequently reversed. The cancellation of this facility not only would have eliminated low-temperature physics from the ISS but also would have compromised the Primary Atomic Reference Clock in Space (PARCS) project, which requires the low-temperature facility for an independent frequency standard, and with it the atomic physics program. Currently, all of the fundamental physics experiments that were planned for Rev. F are still on the ISS flight schedule. These are listed in Appendix D. The resources to have experiments developed, launched, and mounted in place are all essential for advancing to launch. The fundamental physics experiments are all either contained in an external facility or attached at separate external sites (Robey, 2002). The special carriers in which the experiments must be mounted for transport to the ISS, via either the shuttle or another launch vehicle, are a critical resource. As a result of the shift from the Rev. F to the Core Complete design for the ISS, the development of these carriers is now uncertain—clearly, budget constraints will make it difficult for NASA to complete them in a timely fashion. Fundamental physics experiments generally do not require active participation by the crew. However, they do require crew time for external installation of the facilities. The LTMPEF and the laser cooling and atomic physics experiments must each be mounted on the exterior of the ISS by robotic arms operated by the crew. The AMS must be manually mounted by the crew and will require crew extravehicular activities. In addition, any delay after launch in mounting and initiating experiments in the LTMPEF will mean that helium is being lost, reducing the time available for conducting the experiments. In assessing PI readiness to utilize the ISS, it has been difficult to separate the impact of the problems attributable to differences between Rev. F and Core Complete from the impact of existing funding and schedule issues. However, in general PIs have reported that delays in scheduling and uncertainty about the availability of resources have limited their ability to keep their projects operating 7   Also known as LTMPF. 8   This experiment does not officially fall under the Physical Sciences Division at NASA but is included here with other fundamental physics experiments for completeness.

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences optimally. Involving graduate students and junior faculty members without jeopardizing their careers requires a reasonable degree of certainty that projects can be completed in a predictable time. The changes made to the ISS program have directly affected these projects and prevented the PIs from giving them the priority that they would otherwise have had. Factors Limiting Utilization of the ISS There are two major problems limiting ISS utilization by the fundamental physics community: lack of resources and funding instability. The latter problem has been extremely serious. When ISS funding problems have arisen, NASA has tended to cut instrument budgets. The most serious example (for fundamental physics) was the (temporary, as it turns out) cancellation of the LTMPEF in 2001. Furthermore, while no fundamental physics experiments have been canceled, reductions in instrument budgets have forced some PIs to fabricate sections of instruments (e.g., some of the cryostat components for the low-temperature experiments) that could have been purchased, causing further delays. While there are multiple external attachment points for external modules, some of which will be used for the NASA EXPRESS pallet, most of them are too small to accommodate the LTMPEF. It will therefore have to be mounted on the Japanese Experimental Module–Exposed Facility (JEM-EF), which will have the only large carrier attachment points. The JEM-EF is scheduled for installation on the ISS in 2004-2005 (Gregory, 2002) and is a critical requirement for the low-temperature and atomic physics programs. But the reductions in Core Complete have placed the international partner agreements in question, and there is some risk that the JEM-EF may not be completed, which will effectively eliminate the low-temperature research program on the ISS. Finally, the task group wishes to note the impact of flight delays on PI readiness. Two experiments on the heat capacity of helium near the lambda point were performed on shuttle flights in 1992 and 1997. The next experiment will be on the ISS. However, the launch date has been moved back repeatedly, and the time gap between the 1997 experiment and the ISS experiment, currently scheduled for 2005, has become extremely long. The result of this constant slippage of the schedule is that PIs cannot take launch dates seriously and are hesitant to commit the necessary personnel to perfecting the apparatus. Both the lack of resources to complete and fly experiments and overall funding instability have led to the development and launch delays discussed above. As noted previously, this has created considerable uncertainty among fundamental investigators. Given the timing of academic promotion and tenure decisions, it may be problematic for PIs to commit themselves to experiments with unpredictable delays. Also, maintaining a viable research team in the face of such delays is a serious concern. Graduate students and postdoctoral researchers cannot be expected to work indefinitely on the preparation of a spaceflight experiment when launch dates continue to recede into the future, and will most certainly therefore turn to other projects. Maximizing ISS Research Potential The problems preventing the physics community from maximizing the ISS potential come mainly from budgetary decisions that in turn resulted from ISS construction cost overruns. However, some decisions that have had a particularly damaging effect on the viability of the ISS for fundamental physics seem to have been made without considering the scientific implications. To maximize the science return of the ISS in fundamental physics it is important that NASA managers who understand the science and its needs be much more intimately involved in the ISS budget process. It is unlikely, for example, that the initial decision to cancel the LTMPEF would have been made by someone who was aware that it would severely compromise the ability to perform atomic physics experiments on the ISS, as well as eliminate the low-temperature physics experiments on the ISS.

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Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences Finally, the most critical step in maximizing the ISS research potential for fundamental physics is to restore the confidence of the research community. That step will require serious NASA commitments to preventing further slippage of experiment launch schedules, and maintaining adequate funding for those experiments selected for the ISS.