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Space Studies Board Annual Report 2000 (2001)

Chapter: 3. Summaries of Major Reports

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Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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3

Summaries of Major Reports

3.1 Future Biotechnology Research on the International Space Station

A Report of the Task Group for the Evaluation of NASA's Biotechnology Facility for the International Space Station

Executive Summary
BACKGROUND AND SCIENTIFIC SCOPE OF NASA PROGRAMS

The National Aeronautics and Space Administration (NASA) manages research programs in two areas of the rapidly expanding field of biotechnology: protein crystal growth and cell science. The protein crystal growth work focuses on using microgravity to produce higher quality macromolecular crystals for structure determination and on improving understanding of the crystal growth process. The cell science work focuses on basic research that contributes to understanding how the microgravity environment affects the fundamental behavior of cells, particularly in relation to tissue formation and the effects of space exploration on living organisms. The National Research Council 's Task Group for the Evaluation of NASA's Biotechnology Facility for the International Space Station was formed to examine and evaluate the use of the International Space Station (ISS) as a platform for research in these two areas. In this report, the task group offers a variety of recommendations and suggestions for improving the NASA biotechnology research program. It believes these changes are necessary if the NASA program is to fulfill the potential for scientific discovery and impact that is also outlined in this report.

Protein Crystal Growth

The task group heard a great deal about experiments to date in NASA 's macromolecular crystallography program. The results so far are inconclusive, and the impact of microgravity crystallization on structural biology as a whole has been extremely limited. At this time, one cannot point to a single case where a space-based crystallization effort was the crucial step in achieving a landmark scientific result. In many of the cases that have so far been listed as successful, the improvements obtained have been incremental rather than fundamental. In addition, the difficulty of mounting simultaneous efforts to produce the best possible crystals both on the ground

NOTE: "Executive Summary" reprinted from Future Biotechnology Research on the International Space Station, National Academy Press,Washington, D.C., 2000, pp. 1-9

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

and in space has limited the ability of researchers to make the comparisons between microgravity and Earth crystals that would be necessary to demonstrate that the microgravity environment can produce superior crystals.

Finding: The results from the collection of experiments performed on microgravity's effect on protein crystal growth are inconclusive. The improvements in crystal quality that have been observed are often only incremental, and the difficulty of producing the appropriate controls limit investigators' ability to definitively assess if improvements can be reliably credited to the microgravity environment. To date, the impact of microgravity crystallization on structural biology as a whole has been extremely limited.

Despite the lack of impact of microgravity research on structural biology up to now, there is reason to believe that the potential exists for crystallization in the microgravity environment to contribute to future advances in structure determination. Today's ground-based protein crystallization projects are increasingly sophisticated, and yet the diffraction characteristics of crystals of many important targets are still suboptimal. Improvements in diffraction that move a system from the margins of structure determination to well beyond that boundary will have a significant impact on the ability of the resulting structure to provide important insights into biological mechanisms. All research on protein crystallization in space has, up to now, been done under suboptimal conditions (short-duration experiments, insufficient vibration control, etc.), so the improved conditions for research provided by the ISS have the potential to produce much better results.

Finding: While enormous strides have been made in protein crystallization in the last decade, it is still the case that there are very important classes of compelling biological problems where the difficulty of obtaining crystals that diffract to high resolution remains the chief barrier to structural analysis of the crystals. It is here that the NASA program must look to maximize its impact.

In order to engage the research community, NASA must focus its support on programs that are developing technologically innovative equipment and engaging in the structure determination of crystals with important biological implications. While past NASA-supported research on the crystallization process has not been without value, NASA's priority should now be to resolve the community's questions about the usefulness of protein crystal growth in the microgravity environment for tackling important biological questions. Until the uncertainty about the value of space-based crystallization is resolved, a program of this fiscal magnitude is bound to engender resentment in the scientific community.

Although many pharmaceutical and biotechnology companies have participated in microgravity crystallization research, not one has yet committed substantial financial resources to the program. This is likely to remain the case until the benefits of microgravity can be convincingly documented by basic researchers and until facilities in space can handle greatly increased numbers of samples in a much more user-friendly manner.

Cell Science

NASA's cell science program focuses on studying the influence of low gravity on fundamental cell biology as it relates to tissue formation, and on providing insight into the effects of microgravity on cell, tissue, and organ system function, especially as it might affect participants in space exploration.

Finding: It is appropriate for NASA to support a cell science program aimed at exploring the fundamental effects of the microgravity environment on biological systems at the cellular level. Results from such basic research experiments could have a significant impact on the fields of cell science and tissue engineering. However, the specific important questions within cell biology that can best be tackled on the ISS do not seem to have been defined yet. Narrowing the broad sweep of the current program may focus instrument development efforts and accelerate progress toward complete understanding of the effects of microgravity on specific biological phenomena.

A key to determining the success of cell science experiments in space will be designing appropriate controls for experiments. In space, cell cultures experience a low gravitational environment that reduces convection, buoyancy-driven flows, and sedimentation, and it is difficult to separate the various factors causing differences between space-and Earth-grown samples. In addition, the tremendous progress that has been made in three-dimensional tissue

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

development on Earth, under unit gravity, provides a wide range of options for ground-based experiments that may produce results similar to those achieved in microgravity. To evaluate the relative merits of various experimental control groups, and also to enable the detailed evaluation of samples returned from space, it is important that quantitative measures of cell and tissue structure and function be developed and studied.

Finding: Appropriate experimental controls for space-based cell science experiments have not yet been determined. The best controls would be those that enable researchers to separate and investigate the multiple factors—including launch and reentry, effects of microgravity on the culture medium, and direct effects of microgravity on cellular behavior—that produce the changes observed in cells and tissues grown in space. Analytical techniques that measure the molecular mechanisms underlying cellular functions will be essential to provide data for comparing proposed experimental controls and quantifying the observed changes in cell and tissue samples.

At NASA, the work viewed by the task group was being carried out in the biotechnology section of the Microgravity Research Division. The themes of the cell science research under way in this program overlap with the scope of work ongoing in the NASA Life Sciences Division. The complementary nature of these two programs needs to be recognized so that NASA personnel and external researchers can take full advantage of the potential synergies. While there is already a sharing of flight hardware, a mechanism to establish projects that are jointly funded by the Life Sciences Division and the Microgravity Research Division should be considered.

Recommendation: The research strategies and projects of the cell science work in the biotechnology section of the Microgravity Research Division should be more closely coordinated with the work of NASA 's Life Sciences Division to take advantage of overlapping work on bone and muscle constructs and of potential synergies between in vitro and in vivo research projects.

INSTRUMENTATION

The International Space Station (ISS) is currently under construction; assembly is scheduled to be complete in 2005. However, NASA plans to begin research on the facility as early as 2000, using equipment that has been flown on the shuttle and that can be temporarily installed in modules of the ISS as they are completed. As the ISS grows and more station-specific hardware is ready, the research program will expand and more permanent instrumentation will be fitted into the ISS.

Protein Crystal Growth

A variety of equipment has already been used to grow and observe crystals in space, and innovative hardware continues to be developed today. Having multiple laboratories involved in this process encourages variety and creativity and also prevents NASA from getting locked in to a single hardware approach. However, the efforts of hardware developers need to be coordinated and communications between them must be improved to ensure that different programs are not producing instruments with duplicative capabilities and that technological advances are quickly shared and integrated into all equipment where appropriate.

Recommendation: The efforts of external hardware developers should be coordinated to ensure that instruments are compatible, to prevent duplication of efforts, to ensure that technical innovations are shared, and to facilitate input from the scientific community in defining the goals and capabilities of protein crystal growth equipment for the ISS. NASA must also be prepared to discontinue development projects that do not use cutting-edge technologies or that are out of tune with the most current scientific goals.

A significant factor affecting equipment development is the instability in the budget for the ISS. If money is repeatedly siphoned off from the hardware development work, the equipment on the ISS will be of much lower quality than the cutting-edge hardware available on the ground, and researchers will not be interested in using the outdated equipment or willing to entrust precious samples to it.

The equipment developed by and for NASA should aim to provide a high level of control over samples, equipment, and procedures. On the ISS, crew time will be limited, and the human access to samples and the

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

feedback to the investigators enabled by shuttle trips will be infrequent, so automation and ground-based control of experiments are essential. If principal investigators are able to make decisions about experimental parameters and to adjust experiments in real time, the research results produced in each experiment will be of higher quality, and involvement in the NASA program will be more attractive. Therefore, hardware development efforts should emphasize the importance of automation, monitoring, real-time feedback, telemanagement, and sample recovery (via mounting and freezing).

Effective analysis, preservation, and reentry of promising crystal samples is especially necessary given the key role synchrotrons are playing in protein structure determination. If the NASA program is to attract researchers interested in important and challenging biological problems, ISS hardware must be designed to produce and safely return to Earth crystals of the appropriate size and quality to be analyzed at a synchrotron. However, it is not NASA's responsibility to arrange or guarantee this next step. Building a synchrotron beam line is expensive and would not be the most efficient use of NASA's scarce resources. Assuming that NASA's peer review process is selecting the most scientifically rigorous and interesting projects, successful crystallization should enable researchers to compete effectively for the necessary beam time, and success in this extra layer of peer review should further validate the NASA program within the scientific community.

The X-ray Crystallography Facility (XCF) being designed for the ISS is a multipurpose facility designed to provide for and coordinate all elements of protein crystal growth experiments in space: sample growth, monitoring, mounting, freezing, and X-ray diffraction. The task group was impressed by the XCF, the robotics, the remote control, and the range of experimental capabilities provided. The X-ray diffraction module provides valuable information about whether a given crystal will diffract—this real-time feedback is key to making decisions about the success or failure of a particular crystallization experiment and will help allocate scarce freezer resources by ensuring that the most promising crystals are preserved and returned to Earth.

Finding: Automation, monitoring, real-time feedback, telemanagement, and sample recovery (via mounting and freezing) will be vital for successful protein crystal growth experiments on the ISS. The XCF, through its use of robotics and a variety of experimental and observational capabilities, provides many of the tools researchers need to take full advantage of the microgravity environment.

The XCF is typical of several hardware development projects for NASA in that the technologies it employs can be applied to ground-based research capabilities as well as to those based in space. Currently, however, the scientific community is mostly unaware of the quality of the automation displayed in the prototype of the robotic crystal sample preparation system and of the combined capabilities of the X-ray optics and the low-power source that will be used in the XCF. While commercial entities may need to protect their proprietary work, scientists must have access to full information about all relevant technologies and equipment for the ISS in order to effectively design and execute cutting-edge research in space.

Cell Science

A variety of instruments are being developed to support cell science research on the ISS, including a basic incubator, a perfused stationary culture system, and a rotating-wall perfused vessel (a bioreactor). Overall, the NASA-funded cell science work to date has emphasized the use of bioreactors to support three-dimensional tissue growth. While the development of rotating-wall vessels has had, and should continue to have, a significant impact on cell and tissue culturing methodology on the ground, the task group has a variety of concerns about the effectiveness and appropriateness of this approach for research in the microgravity environment. Issues include the relatively small amounts of data generated per unit volume and the difficulty of accessing the vessel on orbit.

Recommendation: Given the current status of equipment in development, finite fiscal resources at NASA, and the limited amount of volume on the ISS, the task group recommends that future research on the ISS should deemphasize the use of rotating-wall vessel bioreactors, which are already established, and continue to encourage the development of new technologies such as miniaturized culture systems and compact analytical devices.

The final determination on what sort of instrumentation will be most effective for cell and tissue growth in microgravity has yet to be made, and it is important that the relative merits of various pieces of instrumentation be

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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carefully evaluated and that NASA maintain the necessary administrative and engineering flexibility to adopt the most effective systems employing the most advanced technologies and to discontinue hardware development projects that are not attuned to the most current scientific needs of the cell science communities. Close interaction is needed between scientists and the NASA operational personnel responsible for developing and constructing the hardware to ensure maximum flexibility and responsiveness to evolving research goals.

Cellular systems are very sensitive to environmental perturbations. A continuous power supply to maintain appropriate and stable environments during experiments and for sample storage and transport is essential to ensure valid results. A variety of systems are under development to manage power distribution, and care must be taken, particularly during ISS construction, to ensure that cell science experiments are not compromised by power fluctuations. Another issue that will be problematic, particularly during ISS construction but also after the station is complete, is the limited amount of crew time available for research. The automation of routine tasks and groundbased control of experiments will be essential if investigators are to make efficient use of the ISS platform.

Two key supports for automation and ground-based control are (1) sensors to enable physiological control of the cell/tissue culture media environment and (2) analytical equipment to provide feedback about the status of cell and tissue samples. The data from the sensors and the on-orbit analyses should be transmitted electronically in real time to investigators to enable ground-based control of experiments. Scientists on the ground then could select the most important samples for the scarce storage space and could study the changes wrought in samples by freezing and reentry.

Finding: The limited amount of crew time available for research-related work and the infrequency with which investigators will have access to their samples via shuttle trips mean that automation of routine tasks, ground-based control of experiments, on-orbit analytical capabilities, and real-time transmission of digital data are vital for conducting effective cell science research on the ISS.

Refrigeration and freezer capability and transport space are not the only factors limiting the throughput of cell science research on the ISS. Other factors that will affect the size of the program and the number of primary publications include crew time required for the experiments, the amount and reliability of the power supply, adequate storage space and appropriate environments for samples and supplies, shuttle flight schedules to and from the ISS, the volume of materials to be transported, and, of course, the size of the budget provided for cell science hardware development and research support. A window of opportunity has been created by the advances in molecular, cellular, and biochemical approaches (e.g., functional genomics and proteomics) that are occurring as the ISS research platform becomes available. The task group recommends that to most efficiently exploit this opportunity, emphasis should be placed on integration of the different approaches and on collaboration between principal investigators and other researchers inside and outside NASA.

Recommendation: Mechanisms should be developed to enable collaborative research projects that maximize the amount of data obtained from each cell or tissue sample by executing multiple analyses on each sample.

Overall Volume Allotment for Biotechnology Research on the ISS

Currently, NASA plans call for peer-reviewed biotechnology research to occur within one rack on the ISS. This rack would be shared by protein crystal growth and cell science work. In addition, two racks are reserved for the hardware associated with the X-ray Crystallography Facility (XCF) being developed for the NASA Space Product Development Division. The task group considered this arrangement and the needs of the various research communities and recommends a shift in the allotments. Namely, the XCF rack devoted to crystal growth and monitoring should be transferred from Space Product Development to the Microgravity Research Division's protein crystal growth program, where experiments are selected by a centralized peer-review process and a full complement of hardware is available. The rack currently scheduled to be shared by cell science and protein crystal growth can then be dedicated entirely to cell science research.

The task group makes this recommendation based on several considerations. A primary issue is the basic incompatibility between the technical needs of cell science and protein crystal growth equipment on the ISS. The flow of gases and fluids required to maintain rigorous environmental control for cell and tissue culture will produce

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

vibrations that cannot be tolerated by a crystal growth facility. If cell science and protein crystal growth equipment are housed in one rack, one or both of the disciplines will be forced to operate under suboptimal conditions.

The task group also carefully considered the needs of the various research communities expected to use the biotechnology facilities on the ISS. For cell science, there was concern that the amount of data and results generated by half a rack of equipment would not be substantial enough to maintain interest within the scientific community, whereas a full rack's worth of instrumentation could raise the program to a critical threshold. For protein crystal growth, the research community is still uncertain about the benefits of growing crystals in a microgravity environment, so protein sample flight programs are undersubscribed and commercial interest is low. By focusing the protein crystal growth research efforts on biologically challenging problems and by emphasizing hardware capable of monitoring and preserving samples, NASA could direct its resources to validating the program. The current volume commitment of half a rack of general macromolecular research is insufficient to establish the value of the crystal growth program, but a full rack, filled with peer-reviewed experiments that employ all types of available hardware and have access to the capabilities of the XCF, should be adequate to give the program a fair chance of success. If, after several years, the results from the protein crystal growth work have provided sufficient proof of microgravity 's benefits and the academic and commercial demand for facilities on the ISS increases, then high-throughput hardware should be developed and the allotment of space on the ISS reconsidered based not only on the demand for macromolecular crystallography research volume but also on the results to that point from the cell science program. Alternatively, if the work done through the augmented commitment recommended here fails to clearly demonstrate the value of microgravity for work on structural biology, then the protein crystal growth program can justifiably be terminated.

Recommendation: The volume allotment for biotechnology work on the ISS should be redistributed as follows:

  • The mounting, freezing, and diffracting equipment of the X-ray Crystallography Facility (XCF) should occupy one rack (as currently planned).

  • The cell science work should occupy the entirety of what is currently designated the Biotechnology Facility.

  • The rack presently assigned to the XCF growth equipment and managed by NASA Space Product Development should be officially dedicated to the peer-reviewed macromolecular research run out of the Microgravity Research Division.

SELECTION AND OUTREACH

NASA research in cell science and protein crystal growth is funded through a collection of approximately 90 active 4-year grants; the total size of the program is roughly $19 million per year. Both ground-based and flight projects are selected through a peer-review process that occurs every other year. While the current grant solicitation mechanism (NASA Research Announcements, or NRAs) is appropriate, it is inadequate to attract the involvement of the best scientists and bioengineers. The task group believes that as the program goes forward, it would benefit from a strengthening of the outreach, selection, and support offered by NASA to ensure that the proposals submitted for consideration are of the highest quality and that everything possible is done to give flight experiments the best chance of success.

Both protein crystal growth scientists and cell science researchers identify themselves with a variety of professional organizations, publications, and conferences, so NRAs should be disseminated to a wider variety of newsletters and announcements in order to reach the multiple communities that might be interested in using NASA biotechnology facilities on the ISS. Another approach to expanding the pool of potential researchers would be to issue NRAs in collaboration with other federal agencies, such as the National Institutes of Health (NIH), the Biotechnology Program in the Engineering Directorate of the National Science Foundation (NSF), the NSF Biological Sciences and Regulatory Biology Divisions, and the Department of Energy. More could also be done to provide sufficient background information for potential investigators who are not familiar with NASA programs. More detail about the special opportunities and constraints of space-based research as well as about the hardware available for the ISS would make it easier for NASA to recruit new applicants for its grants and for those researchers unfamiliar with the NASA program to put together appropriate proposals. Access to information about failed projects would also improve the quality of experiments designed with NRAs in mind and would increase the likelihood of success. In general, results of projects already under way could be more broadly disseminated;

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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however, the task group cautions that presentations should give a balanced portrayal of successes and limitations so as not to raise unrealistic expectations. Misperceptions about the accomplishments of NASA programs can also be gained from press releases that target the general public and portray potential future applications of NASA-funded research as completed or current work. This dissemination of vague or even inaccurate descriptions of its programs seriously diminishes NASA's credibility within the scientific communities.

Recommendation: NASA should improve its outreach activities in order to involve a broader segment of the scientific community in its biotechnology research program and to increase the number of cutting-edge projects submitted for funding. It needs to disseminate NRAs and program results more widely and to provide more complete background information on failed projects and how to design flight experiments.

As the pool of applicants expands, the process of evaluating proposals may also need to be adjusted. NASA's program suffers from longer time scales than are compatible with the current pace of biotechnology research. For example, the 2-year gap between NRA grant submission opportunities is likely to inhibit applications directed at the most cutting-edge research issues. Also, the delay between project selection and flight manifesting of an experiment means that NASA does not always have the hardware flexibility to respond to changes in the field based on new developments in ground-based research (for example, the increased reliance on cryoprotection and freezing of crystals or the use of scaffolding for three-dimensional tissue constructs). Finally, the uncertainties surrounding the NASA budget and the continual schedule changes make people cautious about getting involved in a program that is unable to reliably predict how much money will be available or the schedule for access to the ISS.

One critical step toward raising the profile of the NASA program and the quality of the grant application pool would be to counter the current perception of recipients of NASA funds as a closed community with a fixed membership. On the whole, external input into NASA' s priorities for the biotechnology program seems to be relatively limited. Advisory groups are composed of many of the same people that make up the pool of grantees and contribute to the perception that NASA is not really interested in outside input. By reaching out to a broader slice of the protein crystal growth and cell science communities, NASA would not only increase the quality of the advice it receives but would also be able to educate a new group of people about its programs.

According to NASA, the biotechnology Discipline Working Group (DWG) is the main mechanism for receiving advice about the strategic direction of the Microgravity Research Division's biotechnology programs. The group is responsible for providing input to both the protein crystal growth and cell science sides of the program, but in view of the very different scientific objectives and instrumental requirements, having a single working group for these two disparate areas serves no real purpose. If the DWG is split into two groups, each would be able to focus on the issues most relevant to its own scientific area, and the increased number of slots available for each area would give greater breadth to the groups. Care must be taken in selecting new members to ensure that there is not a bias towards those already working with the NASA program. To attract prominent outside researchers to the DWG, the task group suggests that the name be changed to more accurately reflect the group's role as a high-level advisory panel with input on the scope of research announcements, peer review practices, and future programmatic directions.

Recommendation: The separate identities of the protein crystal growth and cell science sections of NASA's biotechnology research program should be emphasized. One key step should be splitting the Discipline Working Group into two strategic advisory committees to reflect the different issues facing each area of research. Prominent scientists not familiar with NASA's programs but aware of the broader issues facing the fields should be recruited to serve on these committees.

An important issue for execution of research in the unforgiving environment of space is the potential for conflict between the scientific goals of an experiment and the engineering limitations associated with a space-based platform like the ISS. Within the biotechnology scientific community, there is the perception that the NASA culture does not emphasize the importance of communication between scientists and operations personnel, nor does it provide tangible assurances to the research community that the execution of high-quality research in hardware designed to answer the most cutting-edge scientific questions is a NASA priority. The community would be reassured by seeing NASA place bioengineers and biological scientists with the appropriate appreciation of

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

research goals and scientifically oriented reflex responses in high enough decision-making positions to ensure that research opportunities are optimally utilized.

Recommendation: The NASA culture tends to limit communication and coordination between operations personnel and researchers during hardware development; between astronauts and investigators before and during experiment execution; and between decision makers and scientists about the allotment of resources in times of crisis. To attract the best investigators to its biotechnology program, NASA must create an environment geared toward maximizing their ability to perform successful experiments.

Protein Crystal Growth

At present, the primary goal of NASA's protein crystal growth program should be to demonstrate microgravity 's effect on protein crystal growth and to determine whether studies of macromolecular assemblies with important biological implications will be advanced by use of the microgravity environment. To this end, the task group proposes that NASA iniate a high-profile, nationwide series of grants to support researchers engaging in simultaneous efforts to get both the best possible crystal on the ground and the best possible crystal in space of biologically important macromolecules. The projects funded by these grants should address the uncertainties that have plagued the NASA protein crystal growth program, by using the ISS for a reliable, long-term microgravity environment, by comparing space-grown crystals to the best ground crystals, and by focusing on challenging systems and hot scientific problems. Their results should definitively show whether the use of microgravity can produce crystals of a higher quality than those grown using the best technologies available on Earth. If none of the projects produces a space-grown crystal that enables a breakthrough for the structure determination of a biologically important macromolecular assembly, then NASA should be prepared to terminate its protein crystal growth program. However, if the projects supported by this high-profile, nationwide series of grants succeed in validating the use of crystallization in microgravity to tackle important and challenging problems in biology, demand for the facilities on the ISS can be expected to increase. At that time, NASA should develop an external user program (similar to synchrotron user programs) in which projects are selected by a peer-review committee that includes NASA staff representatives.

Recommendation: NASA should fund a series of high-profile grants to support research that uses microgravity to produce crystals of macromolecular assemblies with important implications for cutting-edge biology problems. The success or failure of these research efforts would definitively resolve the issue of whether the microgravity environment can be a valuable tool for researchers and would determine the future of the NASA protein crystal growth program.

Cell Science

NASA has built a very productive relationship with the NIH based on the development and use of rotating-wall vessels. The NASA/NIH Center for Three-Dimensional Tissue Culture was started in 1994 to expose a wider community to bioreactor technology by allowing researchers from government agencies (e.g., NIH, the Food and Drug Administration, and the Department of the Navy) to test new model systems for biomedical research and basic cell and molecular biology in the rotating-wall vessel hardware with technical assistance from experienced NASA personnel. The task group believes that this outreach program is an excellent idea and recommends that a wider range of investigators be reached by opening this introductory phase of this program to extramural (nongovernment) researchers.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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3.2 Assessment of Mission Size Trade-offs for NASA's Earth and Space Science Missions

A Report of the Ad Hoc Committee on the Assessment of Mission Size Trade-offs for Earth and Space Science Missions

Executive Summary

This report addresses fundamental issues of mission architecture in the nation's scientific space program and responds to the FY99 Senate conference report,1 which requested that NASA commission a study to assess the strengths and weaknesses of small, medium, and large missions. To that end, three tasks were set for the Ad Hoc Committee on the Assessment of Mission Size Trade-offs for Earth and Space Science Missions:

  1. Evaluate the general strengths and weaknesses of small, medium, and large missions2 in terms of their potential scientific productivity, responsiveness to evolving opportunities, ability to take advantage of technological progress, and other factors that may be identified during the study;

  2. Identify which elements of the SSB and NASA science strategies will require medium or large missions to accomplish high-priority science objectives; and

  3. Recommend general principles or criteria for evaluating the mix of mission sizes in Earth and space science programs. The factors to be considered will include not only scientific, technological, and cost trade-offs but also institutional and structural issues pertaining to the vigor of the research community, government-industry-university partnerships, graduate student training, and the like.

The committee approached these questions in light of the changing environment at NASA, which has been conducting an increasing number of smaller space and Earth science missions having shorter development times and using streamlined management methods, advanced technologies, and more compact platforms than had been employed in the past. The committee referred to this approach as the faster-better-cheaper (FBC) paradigm, a variant of “smaller, faster, cheaper, better” and similar phrases that have been used to describe the changing environment for space research missions.

The committee interpreted the FBC paradigm as a set of principles (including, but not limited to, streamlined management, flexibility, and technological capability) that are independent of the size or scope of a mission but can be matched appropriately to the science objectives and requirements for a given mission. It understood the term “mission” to mean the entire process of carrying out a space-based research activity, including scientific conception, spacecraft and instrument design and development, selection of development contractors, development costs, selection of launch capability, launch costs, mission operations, data analysis, and dissemination of scientific results.

It is within this broad context that the committee considered questions about the emerging FBC paradigm and its implications for mission size mixes in NASA's Earth and space science programs. How FBC is defined and how FBC principles are applied to programs of any scale have many implications for the space program: its tolerance for risk; its ability to carry out strategic plans; the scope, scale, and diversity of science investigated; the results and analytical products of its missions; the ways it trains young scientists and engineers; the role of international cooperation and the ease with which it can be incorporated into NASA's programs and plans; the role of universities, industry, government laboratories, and NASA centers in conducting space research missions; and the general health and vitality of the space science and Earth science enterprises. Policy makers looking for guidance on these programs in terms of cost and size trade-offs should be made aware that the variables are more numerous and much more complex than might at first be supposed.

NOTE: "Executive Summary" reprinted from Assessment of Mission Size Trade-offs for NASA's Earth and Space Science Missions,National Academy Press, Washington, D.C., pp. 1-5.

1  

U.S. Senate. 1998. Department of Veterans Affairs, Housing and Urban Development, and Independent Agencies Appropriations Bill, 1999, 105th Congress, 2nd Sess., S. Rept. 105-216.

2  

For the purposes of this study, NASA defined “small” as missions with total life-cycle costs less than $150 million, “medium” as between $150 million and $350 million, and “large” as more than $350 million.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

The FBC approach emerged from the widely held belief that some large, traditional NASA missions had become unwieldy. With development times of over a decade (which often resulted in flying less capable technologies) and escalating costs, such missions came under increasing scrutiny, even given the magnificence of their promised (and realized) scientific returns. Traditional missions called into question the ability of NASA's Earth and space science research programs to obtain the highest quality and quantity of research return in the most timely and efficient fashion. Cuts in NASA's budget beginning in the early 1990s further encouraged new approaches for obtaining scientific returns in more efficient and cost-effective ways, albeit with added risk.

“Faster” missions can be made so by streamlining the management and development effort, by shortening the development schedule, by using the best available technology, and perhaps even by knowingly accepting more risk. In general, such methods will also lead to a “cheaper” mission. However, for NASA research programs, technological or managerial innovation are not ends unto themselves: the clear and obvious meaning of “ better” is that more science—more knowledge and better quality and quantity of measurements—about some aspects of the universe around us is returned for a given investment and that such returns occur in a timely manner.

The impression that faster-better-cheaper also means “smaller” has raised concerns that there is a growing shift away from larger-scale endeavors in the Earth and space science programs. However, the tendency to equate FBC with the size or cost of a space or Earth science mission can overlook a number of things: the requirements unique to different disciplines, the complexities of scientific objectives, time and spatial scales, and techniques for implementing a mission. Total costs, mission capabilities, and the ultimate scientific results of space programs rely on a complex combination of the skill and performance of everyone associated with mission development, schedules, approaches to handling technical and management risks, technological implementation, and management style.

Through the careful planning processes that now characterize both the Earth science and the space science enterprises, the key outstanding questions of each discipline can be framed. Each such science question or disciplinary quest must then be examined in terms of the science community's priorities, the measurement requirements, and the technological readiness to determine which mission approach (or approaches) might be employed to address it. These science-based decisions on missions and approaches also incorporate strategies to engage and educate the general public and contribute to broader goals such as human exploration and development of space. A major consideration in all cases is the fiscal constraint that applies at any given time and the level of risk that can be tolerated by the mission's scientific priority and its role in NASA's strategic plan.

The ad hoc committee recognizes that the recent losses of missions conducted using the FBC approach—Lewis, the Wide-Field Infrared Explorer, Mars Climate Observer, and Mars Polar Lander—are in many ways calling into question some elements of the philosophy of FBC. Although it is beyond the scope of the committee's charge to assess individual mission failures (this is a task for the mission failure review boards), the committee calls attention to the potential implications of these losses for science and, especially, for the direction of the NASA Mars program. Is the Mars program committed to a technology path that is proving to be riskier than its proponents originally anticipated? Are recent losses turning the program toward sample return missions that lack the critical precursors recommended in science strategy reports? How seriously have the scientific rationale and robustness of the Mars program been affected by the information lost from recent mission failures? Do current and future mission programs have ample time and budgets to integrate the lessons learned from previous failures? These and other ramifications of the recent series of losses of missions implemented under the FBC paradigm are of pressing and paramount concern.

FINDINGS

The committee supports several principles being implemented in the FBC methodology. Specifically, it found a number of positive aspects of the FBC approach, including the following:

  • A mixed portfolio of mission sizes is crucial in virtually all Earth and space science disciplines to accomplish the various research objectives. The FBC approach has produced useful improvements across the spectrum of programs regardless of absolute mission size or cost.

  • Shorter development cycles have enhanced scientific responsiveness, lowered costs, involved a larger community, and enabled the use of the best available technologies.

  • The increased frequency of missions has broadened research opportunities for the Earth and space sciences.

  • Scientific objectives can be met with greater flexibility by spreading a program over several missions.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

Nonetheless, some problems exist in the practical application of the FBC approach, including the following:

  • The heavy emphasis on cost and schedule has too often compromised scientific outcomes (scope of mission, data return, and analysis of results).

  • Technology development is a cornerstone of the FBC approach for science missions but is often not aligned with science-based mission objectives.

  • The cost and schedule constraints for some missions may lead to choosing designs, management practices, and technologies that introduce additional risks.

  • The nation's launch infrastructure is limited in its ability to accommodate smaller spacecraft in a timely, reliable, and cost-effective way.

RECOMMENDATIONS TO NASA
Faster-Better-Cheaper Principles

Faster-better-cheaper methods of management, technology infusion, and implementation have produced useful improvements regardless of absolute mission size or cost. However, while improvements in administrative procedures have proven their worth in shortening the time to science, experience from mission losses (Mars Climate Observer and Lewis, for example) has shown that great care must be exercised in making changes to technical management techniques lest mission success be compromised.

Recommendation 1:

Transfer appropriate elements of the faster-better-cheaper management principles to the entire portfolio of space science and Earth science mission sizes and cost ranges and tailor the management approach of each project to the size, complexity, scientific value, and cost of its mission.

Science Scope and Balance
  • The nature of the phenomena to be observed and the technological means of executing such observations are constrained fundamentally by the laws of physics, such that some worthwhile science objectives cannot be met by small satellites.

  • The strength and appeal of faster-better-cheaper is to promote efficiency in design and timely execution—shorter time to science—of space missions in comparison with what are perceived as less efficient or more costly traditional methods.

  • A mixed portfolio of mission sizes is crucial in virtually all space and Earth science disciplines in order to accomplish a variety of significant research objectives. An emphasis on medium-size missions is currently precluding comprehensive payloads on planetary missions and has tended to discourage planning for large, extensive missions.

Recommendation 2:

Ensure that science objectives—and their relative importance in a given discipline—are the primary determinants of what missions are carried out and their sizes, and ensure that mission planning responds to (1) the link between science priorities and science payload, (2) timeliness in meeting science objectives, and (3) risks associated with the mission.

Technology and Instrumentation
  • Technology development is a cornerstone of first-rate Earth and space science programs. Advanced technology for instruments and spacecraft systems and its timely infusion into space research missions are essential for carrying out almost all space missions in each of the disciplines, irrespective of mission size. The fundamental goal of technology infusion is to obtain the highest performance at the lowest cost.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×
  • The scientific program in Earth and space science missions conducted under the FBC approach has been critically dependent on instruments developed in the past. The ongoing development of new scientific instrumentation is essential for sustaining the FBC paradigm.

Recommendation 3:

Maintain a vigorous technology program for the development of advanced spacecraft hardware that will enable a portfolio of missions of varying sizes and complexities.

Recommendation 4:

Develop scientific instrumentation enabling a portfolio of mission sizes, ensuring that funding for such development efforts is augmented and appropriately balanced with space mission line budgets.

Access to Space
  • The high cost of access to space remains one of the principal impediments to using the best and most natural mix of small and large spacecraft. While smaller spacecraft might appear to be the right solution for addressing many scientific questions from orbit, present launch costs make them an unfavorable solution from an overall program budgetary standpoint. Moreover, larger missions, too, are plagued by the excessive costs per unit mass for present launch vehicles.

  • The national space transportation policy requiring all U.S. government pay loads to be launched on vehicles manufactured in the United States prevents taking advantage of low-cost access to space on foreign launch vehicles.

Recommendation 5:

Develop more affordable launch options for gaining access to space, including—possibly—foreign launch vehicles, so that a mixed portfolio of mission sizes becomes a viable approach.

International Collaboration
  • International collaboration has proven to be a reliable and cost-effective means to enhance the scientific return from missions and broaden the portfolio of space missions. Nevertheless, it is sometimes considered, within NASA, to be detrimental, perhaps because it adds complexity and can bring delays to a mission. It is also perceived to give a mission an unfair advantage and, in part, to increase NASA's financial risk.

  • In the past, NASA had within its budgets an international payload line, which was an extremely useful device for funding the planning, proposal preparation, and development and integration of peer-reviewed science instruments selected to fly on foreign-led missions. This line offered the U.S. scientific community highly leveraged access to important new international missions by providing investigators with additional opportunities to fly instruments and retrieve data, especially during long hiatuses between U.S. missions in a given discipline.

Recommendation 6:

Encourage international collaboration in all sizes and classes of missions, so that international missions will be able to fill key niches in NASA's space and Earth science programs. Specifically, restore separate, peer-reviewed announcements of opportunity for enhancements to foreign-led space research missions.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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3.3 The Role of Small Satellites in NASA and NOAA Earth Observation Programs

A Report of the Committee on Earth Studies

Executive Summary

At the request of the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA), the Committee on Earth Studies analyzed the capability of small satellites to satisfy core observational needs in Earth observing and environmental monitoring programs. The committee's study focused in particular on the use of small satellites to be inserted in the NASA Earth Observing System (EOS) program and the planned NOAA-Department of Defense (DOD) National Polar-orbiting Operational Environmental Satellite System (NPOESS) program.1

The committee's study was begun in November 1995, during a period of much debate over the feasibility and merits of substituting smaller satellites for larger systems. Proponents of the small satellite approach believed that advances in miniaturization would allow development of much smaller sensors with performance sufficient for many Earth science and operational needs. These smaller sensors could be accommodated on capable, smaller spacecraft and launched with the new generation of smaller launch vehicles. Further, they argued, performing missions with smaller payloads, spacecraft, and launch vehicles would lead to lower costs, greater programmatic flexibility, more and faster missions, and accelerated infusion of new technologies. These features would help fill recognized gaps and provide new opportunities in the nation's Earth observation programs.

The committee approached the study by setting out to understand the observational needs for key NASA and NOAA Earth remote sensing programs, and to determine and assess the availability and capability of sensors, satellite buses, and launch vehicles suitable for small satellite missions. The committee examined opportunities presented by small satellite options with respect to mission architecture and assessed their implications for future NASA and NOAA missions.

SMALL SATELLITES VERSUS SMALL MISSIONS

The committee found that, in addressing the role of small satellite missions, it is important to distinguish between small satellites, small missions, and larger missions employing small satellites. In this study, the term “small satellites” refers to size—satellites in the 100 to 500 kg class capable of meeting NASA and NOAA Earth observation measurement requirements. The term “small mission” refers to cost—that is, a small mission is a comparatively low-cost mission. NASA 's current Earth science strategy of performing a larger number of smaller missions (versus that planned in earlier conceptions of the EOS program) is predicated on the cost of each mission being relatively low. Although small satellites may help enable low-cost small missions, not all small satellite missions will be low cost. Low costs result as much from the relative simplicity of the mission (or the preexistence of mission elements) as from the size of the satellite.

The ability to achieve low costs when employing small satellites for larger missions is even more uncertain than when small satellites are employed for small missions. For example, performing a mission with a large constellation of small satellites to achieve a high sampling frequency may cost a great deal, even though the individual satellites may cost little. A more controversial example is to use small satellites as a substitute for larger satellites to accommodate a specified complement of sensors. In this trade-off, the cost of initially placing the sensors into orbit may be higher with multiple small satellites because it involves building and launching more satellites. The lowest cost architecture to maintain a functioning complement of sensors over a prescribed mission

NOTE: "Executive Summary" reprinted from The Role of Small Satellites in NASA and NOAA Earth Observation Programs,National Academy Press, Washington, D.C., 2000, pp. 1-6.

1  

EOS is the space-based component of NASA's Earth Science Enterprise (formerly known as the Mission to Planet Earth program). Currently, the Department of Commerce, through NOAA, supports the Polar-orbiting Operational Environmental Satellite weather satellite system, and DOD, through the Air Force, supports the Defense Meteorological Satellite Program weather satellite system. NPOESS will be supported by NOAA and DOD and will be managed by the Integrated Program Office staffed by NOAA, DOD, and NASA personnel.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

lifetime depends on the system availability requirements (i.e., the percentage of time the system must be able to deliver the specified data) and the design life and reliability of the mission elements (sensors, spacecraft bus, launch vehicles).

MEETING CORE OBSERVATIONAL NEEDS

NASA's and NOAA's core Earth observational needs span many disciplines, including oceanography, land processes, atmospheric sciences, meteorology, climate, and geodesy. While these aspects of Earth studies have shared remote-sensing spacecraft, the mission goals for the different disciplines often have different mission time horizons, different orbit requirements, and differing instrument sizes and require measurements of differing resolution, repeat cycle, and area coverage, for example. Although it is sometimes necessary (or at least very desirable) that some of these data be temporally and geographically coincident to some tolerance, accommodating these diverse mission goals with large, multisensor spacecraft generally involves compromises. The committee has sought to understand these requirements and compromises to help assess the capabilities and opportunities associated with small satellites.

A primary argument for a multisensor platform is a requirement for temporal or spatial simultaneity of data collection—for example, when studying the interaction between columnar water vapor and temperature, or when there is a desire to test for the presence of clouds in the field of view. However, the committee found the requirement for simultaneity difficult to prove. Generally, only a need to observe clouds or other rapidly changing conditions supported the argument for simultaneity. Rather, it is more important to ensure that a full suite of sensors is contemporaneously available to measure processes related to coupling of various components of the Earth system, such as air/sea fluxes, and that this suite is continued for a sufficient period of time. For operational systems, strict simultaneity is also not generally required. Because the sensors are not all co-boresighted and because some have inherently different sampling strategies, even operational satellite platforms that carry multiple sensors mostly provide contemporaneous rather than simultaneous observations. Even in those cases where simultaneity is required, there may be opportunities to use alternative architectures—for example, clusters of satellites flying in formation.

Although there are differences between the operational measurement requirements of missions such as NPOESS and the Earth science research requirements of missions developed by NASA's Earth Science Enterprise, there is clearly overlap as well. Moreover, many operational measurements are useful for research, especially for long-term climate studies. The separation of instrument variability from the often subtle long-term variations in climate-related processes requires careful calibration and validation of the sensor and its derived data products. As sensors are replaced over time, it is essential to maintain continuity of the data product despite changes in sensor performance (“dynamic continuity”).

The requirements for research missions evolve rapidly with advances in science and technology. Long development times associated with large multisensor missions often run counter to this emphasis on flying the latest in sensor design. Research missions emphasize the quality of the individual observation and thus constantly push the technology envelope in an attempt to obtain better-quality data. By contrast, operational systems tend to evolve more slowly, in part in response to budgets that grow more slowly and in part in response to the well-defined operational nature of the missions. For example, the data processing infrastructure of the user community often involves numerical models that may be expressly designed to assimilate satellite measurements collected at specific times with specific observing characteristics.

CAPABILITY OF SMALL SATELLITES TO PERFORM EARTH OBSERVATION MISSIONS

A review of development trends points to continued efforts to increase capability, reduce size, and lower costs of small satellite buses. In particular, technology has advanced to the point where very capable buses are currently available for performing many Earth observation missions. However, some Earth observation payloads are too large, too heavy, too demanding of power, or generate too much vibration to be accommodated efficiently with small satellite missions. Future advances in pay load technology should mitigate this situation, but there are fundamental laws of physics that in some cases restrict the degree of miniaturization that can be achieved while retaining sufficient performance to meet the observation requirements. Thus, the committee sees small satellites as a complement to larger satellites, not a replacement for them.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×
FLEXIBILITY AND NEW OPPORTUNITIES PROVIDED BY SMALL SATELLITES

Small satellites offer new opportunities to address the core observational requirements of both operational and research missions. Small satellites, in particular single-sensor platforms, provide great architectural and programmatic flexibility. They offer attractive features with respect to design (distribution of functions between sensor and bus); observing strategy (tailored orbits, clusters, constellations); faster “time to science” for new sensors; rapid technology infusion; replenishment of individual failed sensors; and robustness with regard to budget and schedule uncertainties. New approaches to observation and calibration may be possible using spacecraft agility in lieu of sensor mechanisms, for example. Small satellite clusters or constellations can provide new sampling strategies that may more accurately resolve temporal and spatial variability of Earth system processes.2 With advances in technology and scientific understanding, new missions can be developed and launched without waiting for accommodation on a multisensor platform that may require a longer development time.

Small satellite missions, as a new element of measurement strategy, may also help provide more balance between long-term operational or systematic observations and short-term experimental process measurements, as well as between focused missions and larger, more comprehensive missions. Programs can be more readily tailored to fiscal funding constraints when implemented as a series of smaller satellites (although this raises the risk of an incomplete data set unless the missions are planned and executed carefully).

AVAILABILITY OF RELIABLE LAUNCH VEHICLES

Achieving the full promise of small satellites will require the availability of reliable U.S. launch vehicles with a full range of performance capabilities. This is currently not the case. Present launch vehicle performance capabilities do not effectively span the range of potential pay loads. For example, there is a significant gap in capability between the Pegasus-Athena-Taurus launch vehicles and the Delta II. Also, fairing volume (which determines the stowed payload size as well as the type and complexity of deployable systems such as antennas) is often limited and sometimes drives the size of the payload. More flexible launch systems are needed where volume constraints are less stringent. Further, early experience with the new small launch vehicles has included a number of failures, and the present paucity of reliable options is of great concern. This is likely due in part to the relative newness of these systems and a desire to minimize development costs for these commercial ventures. Continued development should overcome the difficulties and yield a suitable balance between cost and reliability. It will take some time, and likely some additional failures, before any of these launch vehicles establish a reliability record approaching that of the Delta II. Plans by numerous suppliers to address these needs are encouraging.

COST OF SMALL SATELLITE MISSIONS

Small spacecraft do offer opportunities for low-cost missions, but very low costs are experienced only with simple spacecraft performing limited missions. Small spacecraft can be relatively expensive when they retain the complexity required to meet demanding science objectives (pointing accuracy, power, processor speed, redundancy, etc.). Commercial “production” satellite buses offer the potential for reducing costs.3 However, they generally have to be tailored—with attendant costs—to accommodate existing Earth observation payloads. Designing new payloads to match existing bus capabilities offers greater cost-effectiveness, but caution must be exercised not to compromise the scientific mission in so doing.

Several small missions—e.g., Clementine, QuikSCAT (Quick Scatterometer)—consisting of a single small satellite launched on one of the new class of small launch vehicles have been successfully performed at a relatively low cost. But the true cost of these missions is somewhat controversial in that they employed preexisting sensors and technology developed under separate funds. The true cost of a mission must also include the investment in technologies around which the activity is built. Leveraging advanced technology to lower mission costs is laudable,

2  

Clusters are a collection of two or more satellites relatively closely spaced in a common orbit (formation flying). Constellations (e.g., Global Positioning System, Iridium) are a collection of satellites whose relative positions are controlled in each of multiple orbits.

3  

Commercial spacecraft buses are those for which there exists an operating production line serving a commercial market, as is the case for some communication satellites (e.g., Iridium).

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

but understanding the true cost of the mission requires consideration of such prior investments, particularly when they are directly supportive of the mission (e.g., preexisting sensors).

SENSOR DEVELOPMENT

The factors driving mission development time and cost for Earth observation missions are typically associated with the development of sensors. “Standard” small satellite buses and launch vehicles are available to support faster missions, but development of new sensors will often control a program's schedule regardless of satellite size. Small satellites can provide a quicker path to operation and data collection if the required instruments—sized to the smaller spacecraft—are available, or if they are under development on a schedule that matches the development timetable of the spacecraft. Many of the early successes with smaller, faster missions depended on the availability of sensors developed elsewhere (e.g., Clementine, QuikSCAT). Whereas larger mission budgets and schedules have traditionally provided for their own sensor development needs, continued success with fast, cheap, small missions will require a reservoir of new sensor technology developed through alternative sources. If small missions are burdened with the development of their sensors, then the cost, the development time, and the time to science will increase accordingly.

MISSION ARCHITECTURE

The development of highly capable small satellites has given new flexibility to planners when designing mission architectures. Small satellites offer program managers flexibility that is useful for both operational and research missions. For example, operational missions might employ small satellites to ensure minimum gaps in critical data records, while research missions might use small satellites to ensure short time to science. Constellations or clusters of small satellites also afford new strategies for acquiring data or for accommodating fiscal funding constraints.

Larger, multisensor platforms have advantages as well. When needed, they provide a more stable platform and facilitate spatial and temporal simultaneity of measurements. Because fewer spacecraft and launches are involved, multisensor platforms offer a higher probability of placing a given complement of sensors into orbit without loss—and, often, at lower initial cost. Multisensor platforms frequently offer the simplest ground segment solutions, including mission operations, downlink and data system architectures, and calibration and validation of sensors.

The trade-off between small and large platforms is a complicated function of overall mission objectives, available budgets, tolerance for risk, and success criteria. These criteria are significantly different for research and operational missions. For example, operational systems are judged by performance, life cycle cost, and availability (the percentage of time the system can provide timely delivery of data). Loss of a single critical sensor can result in mission failure. Multiple launches of small satellites carry a higher risk of a launch or satellite failure, although the impact of such a failure with a larger multisensor satellite can be greater. Research missions are more tolerant to partial failure and place higher value on dynamic continuity and data quality as well as the flexibility to pursue new sensors and new science requirements aggressively.

The committee found that life cycle cost trade-offs between multisensor platforms and multisatellite architectures are driven by the reliability and design lives of the system elements (sensors, satellite buses, launch vehicles, ground segments) and by availability requirements for operational systems. The following conclusions pertain, depending on these requirements and system element characteristics:

  • The lowest cost to place a given set of sensors into orbit will often be with the smallest suitable multisensor platform.

  • The lowest cost architecture to maintain a set of operational sensors in orbit for a sustained mission life is mission specific and must be determined on a case-by-case basis.

  • Small satellites may provide economic benefits as part of a replacement strategy for failed sensors or for sensors with limited design life or reliability.

Small and large satellite architectures show differing life cycle cost sensitivities to sensor reliability for sustained missions. As a result, there are conditions for which large satellite architectures are most cost-effective, as well as conditions that favor small satellites. Large satellite architecture costs are more sensitive to sensor reliability

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

because larger satellites carry more sensors, all of which are replenished if a new satellite is launched in response to a critical sensor failure. When sensor reliability is high and failure infrequent, the lower cost of deploying the payload on fewer, larger platforms outweighs the added costs of occasionally launching unnecessary sensors and provides a life cycle cost advantage to large satellite architectures. But low sensor reliability, with concomitant frequent replenishment, leads to excessive unnecessary sensor replacement with large platforms, thus favoring small satellite architectures.

The often complex evaluation of whether the use of a small satellite is appropriate is driven by mission-specific requirements, including those related to the policy and execution of the program, fiscal constraints, and the scientific needs of the end users. Considering the many issues involved, the design of an overall mission architecture, whether for operational or research needs, requires a complete risk-benefit assessment for each particular mission. For some missions, a mixed fleet of small and large satellites may provide the most flexibility and robustness, but the exact nature of this mix will depend on mission requirements.

MANAGEMENT OF SMALL SATELLITE PROGRAMS

Innovative management approaches are needed to exploit the potential advantages offered by the small satellite approach if, as the committee believes, missions are to be science-driven versus technology-driven. New management approaches would benefit the development and implementation of calibration and validation strategies that maintain data continuity between sensors on successive satellites.

Fresh management approaches include streamlining program management and reducing management overhead, which can easily slow system development or discourage innovation, thus inhibiting many of the advantages of the small satellite approach. Small, tightly integrated teams have an advantage in such a development process as overhead costs decrease with team size. Experience shows, however, that efforts to reduce costs may result in severe pressures on the team. New approaches to program management can mitigate this problem. For example, government insight as part of the development team can limit the need for oversight by limiting formal reviews and documentation to those that truly add value.

Experience to date with small satellite missions offers many lessons on efficiencies achieved and risks associated with streamlined management techniques. Several missions have been quite successful, but delayed sensors, spacecraft development problems, launch vehicle availability and failure, and inadequate mission operations plans have all led to delays, cost increases, cancellation, and/or total loss. We must learn from these successes and failures to attain the full promise of small satellites in the future.

A common theme from the cases studied is that the attempt to achieve faster and cheaper missions by streamlining operations and reducing non-value-added tasks must also include plans to maintain balance among all program elements. Imbalances among the sensor, spacecraft bus, launch vehicle, and ground system elements can lead to serious inefficiencies and risks. Risk must be carefully assessed for all program elements when defining the system, particularly for schedule-critical missions. For the greatest cost-effectiveness, risk should be continuously assessed, progress monitored, and plans adjusted to keep the total program in balance. There is also a need for well-defined, well-understood, and consistent roles for government and industry partners and regular communication between all parts of the team.

MISSION PLANNING

User tolerance of risk is a key consideration when planning research or operational Earth observation programs. Some Earth science missions require access to long-term, consistent data sets from a variety of sensors. Operational systems, such as meteorological satellites, have strict requirements for data availability from multiple sensors for short-term and long-term forecasting. Although the risks for the individual small satellite components may be higher, small satellites may allow the design of a resilient, robust system (e.g., constellation of satellites) where the total mission risk is smaller. Thus, management structures must not only allow the benefits of small satellites to be realized, but must also enable assessment and mitigation of the new set of risks posed by new mission architectures.

Traditional procedures to develop mission and sensor concepts and the associated peer review process need to be streamlined. First, there must be appropriate mechanisms to ensure the design and maintenance of a coherent observing strategy. For example, solicitations for new NASA science missions should be consistent with the overall

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

science directions of the Earth Science Enterprise. Second, management must address the issues associated with maintaining dynamic continuity of long-term data sets where the specific sensors (and even measurement techniques) will change over time. A comprehensive plan for cross-sensor calibration, data validation, and prelaunch characterization is especially important for climate research. Third, the science community must be prepared to make quantitative evaluations of sampling issues versus measurement quality in regard to the overall quality of the data products. This includes an evaluation of the impacts of data gaps as well as of levels of temporal and spatial resolution. The science community should be involved throughout the system design and implementation process rather than be limited to providing measurement requirements at the initial design stages. Regular assessments of sensor and system design, data products, and algorithms are needed to provide science community insight into the process.

CONCLUSION

The committee finds that the maturation of remote sensing science and the development of new sensor, platform, and launcher technologies now allow a more flexible approach to both research and operational Earth remote sensing. Small satellite missions have provided and should continue to provide an important component of how Earth observations are conducted from space. However, their limitations—both evident and more subtle—suggest that they are not an appropriate substitute for all larger satellites. The committee recommends that, in planning for future NASA and NOAA missions, the choice of mission architecture should be driven by the mission requirements and success criteria, and an optimum solution should be sought, whether with large, mid-size, small, or a mixed fleet of platforms. The committee also recommends that both the research and operational communities perform a complete analysis of sampling strategies in the context of potential new mission architectures.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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3.4 Microgravity Research in Support of Technologies for the Human Exploration and Development of Space and Planetary Bodies

A Report of the Committee on Microgravity Research

Executive Summary
CHARGE TO THE COMMITTEE AND REPORT ORGANIZATION

The primary charge to the Committee on Microgravity Research (CMGR) from the Microgravity Science and Applications Division (MSAD)1 of NASA reads:

CMGR will undertake an assessment of scientific and related technological issues facing NASA's Human Exploration and Development of Space (HEDS) endeavor. The committee will look specifically at mission enabling and enhancing technologies which, for development, require an improved understanding of fluid and material behavior in a reduced gravity environment. These might range from construction assembly techniques such as welding in space, to chemical processing of extraterrestrially derived fuels and oxygen. The committee will identify opportunities which exist for microgravity research to contribute to the understanding of fundamental science questions underlying exploration technologies and make recommendations for some areas of directed research.

In addition to the above charge, the committee was asked to give some consideration to radiation hazards and shielding.

The committee and MSAD mutually interpreted the main thrust of the charge to be the determination of the gravity-related physicochemical phenomena most relevant to HEDS technology needs and the recommendation of fundamental research on those phenomena. The technologies considered were those judged to be relevant in the next one to three decades.

The organization of this report reflects the committee's interpretation of the charge. Following the introduction and brief descriptions of relevant phenomena and concepts, the report surveys a set of selected HEDS-enabling technologies, classified according to function. The survey is intended not to be comprehensive but to identify those underlying scientific phenomena that are vital to the technologies, that are gravity related, and that present a compelling need for research. The committee defines a gravity-related phenomenon as a phenomenon that is either directly affected by reduced gravity or that becomes significant as gravity level is reduced. A phenomenon of the latter type may sometimes be used to compensate for the loss of gravity (an example is surface-tension-driven flow in wicks and heat pipes in the absence of gravity-induced convection). Selected phenomena and their dependence on, or importance in, reduced gravity are then discussed, along with the research needed to develop predictive models and better databases for characterizing the phenomena. The remainder of the report deals with other gravity-related features of HEDS technologies, discusses microgravity countermeasures (e.g., artificial gravity), and offers research and programmatic recommendations.

TECHNOLOGIES SURVEYED

The selected technologies are discussed according to their functions: (1) power generation and storage, (2) space propulsion, (3) life support, (4) hazard control, (5) materials production and storage, and (6) construction and maintenance. They were examined for their dependence on gravity level by considering the gravity dependence of the components (subsystems) or processes of which they are made up. In many instances, the subsystems (e.g., pumps or boilers) or processes (e.g., electrolysis) are common to many technologies, so the phenomena underlying them were recognized as especially important for HEDS. An example of a strongly gravity-dependent subsystem is a heat exchanger subsystem, such as a boiler or a condensation-based space radiator, that uses a two-phase fluid

NOTE: "Executive Summary" reprinted from Microgravity Research in Support of Technologies for the Human Exploration and Development of Space and Planetary Bodies, National Academy Press, Washington, D.C., 2000, pp. 1-7.

1  

Now the Microgravity Research Division.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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(i.e., liquid and vapor). Its operation is radically affected by microgravity because the phenomena of buoyant convection and density stratification are absent. An example of a strongly gravity-dependent process is liquid electrolysis, common to life support and fuel production systems. The phenomenon of buoyancy-driven migration of the gases (i.e., bubbles) in the liquid does not occur in microgravity, so phase separation of the product gases from the liquid must be accomplished by other means.

Although the charge to the committee did not specifically include an evaluation of technologies, a remark on this point seems in order. Now and in the past NASA has chosen not to use active, high-power-density systems that involve heat transfer by phase change (e.g., condensation and boiling) to meet energy needs but has chosen instead to use lower-power-density, passive systems such as solar collectors, fuel cells, and radio isotope generators. This approach has been motivated by the requirement to reduce risk and to ensure reliability, since the performance of multiphase (two or more phases) flow and heat transfer processes in reduced gravity is not well understood and is therefore considered risky. Unfortunately, however, the lower-power-density systems will not be able to supply enough energy for proposed long-duration, crewed space and interplanetary missions. The high efficiency and high power-to-weight ratio of closed-cycle multiphase systems, based on the use of the latent heat of phase change (i.e., condensation and evaporation) to transfer energy, are so attractive that the committee believes it is imperative for NASA to undertake a directed research program on multiphase flow and heat transfer that will enable it to decide if these systems can be successfully controlled and utilized in space. Accordingly, one of the higher-priority recommendations proposes this research.

PHENOMENA IDENTIFIED AS AFFECTED BY OR DOMINANT IN REDUCED GRAVITY

Phenomena that are identified as underlying HEDS-enabling technologies and that are either directly affected by gravity level or emerge as dominant factors in reduced gravity are generally organized in Chapter IV of this report as follows: (1) surface and interfacial phenomena, referring to effects stemming from surface wetting and interfacial tension; (2) multiphase flow and heat transfer, referring to the flow of more than one fluid phase in pipes, pumps, and phase change components, and flow in porous media, exemplified by the flow of fluids in the packed and fluidized particulate beds used in chemical reactors; (3) multiphase system dynamics, which deals with the global instabilities that may occur in multiphase systems; (4) solidification, referring to the phase change of a liquid to a solid, as occurs in casting or welding; (5) fire phenomena and combustion, used in some power generation and propulsion systems and occurring in accidental fires; and (6) granular mechanics, referring to such topics as the response of granular media and soils to geotechnical loads and the flow of granular materials in chutes and hoppers.

RECOMMENDED HIGHER-PRIORITY RESEARCH ON FUNDAMENTAL PHENOMENA

Of the specific areas recommended for research in this report, those discussed below were considered by the committee to have higher priority based on their potential to affect a wide range of HEDS technologies that are mission enabling. In each area, the technological importance of the phenomena is briefly explained first.

Surface or Interfacial Phenomena

Surface tension effects are of critical importance in such diverse HEDS technologies as welding, liquid-phase sintering, the operation of wicks in heat pipes for thermal management, the use of capillary vanes (wet by the liquid) in cryogenic storage tanks to control the position and movement of liquids, lubrication, and boiling/condensation heat transfer, including the rewetting of hot surfaces. A special (Marangoni) effect occurs when the surface tension varies over the surface of a liquid (or the interface between two liquids) because of thermal and composition gradients. Marangoni effects can produce strong gravity-independent convection, which may be beneficial, as in the stirring of weld pools and the enhancement of the critical heat flux in multicomponent boiling, or detrimental, as in the migration of fluid in a thermal gradient to unwanted locations.

The committee's recommendations, which are based on the critical issues underlying the technologies, call for research on the following topics:

  • The physics of wetting, with an emphasis on hysteresis effects, the dynamics of the wetting process, and the molecular basis of wetting, to elucidate the wetting of both solid and porous media (e.g., wicks and nanoscale

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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media) and to provide a basis for the choice of material combinations and conditions for optimal wetting and wetting agents;

  • Capillary-driven flows, with modeling of the flows induced by the Marangoni effect, which are complicated because of the feedback between the flow and the surface temperature and composition gradients that drive the flow.

Multiphase Flow and Heat Transfer

Multiphase flow and heat transfer are the fundamental processes in systems using a fluid of two or more phases (e.g., liquid and vapor) to transport mass, momentum, and energy. They are critical to the operation of many power production and utilization systems and other systems that require high energy-transport efficiency and high power-to-weight ratios. Multiphase systems have these characteristics because they are able to utilize the latent heat of evaporation/condensation to efficiently transfer energy. Their successful operation in Earth 's gravity often depends on buoyancy-driven convection and density-induced stratification of the phases, processes that are reduced or absent in microgravity. Moreover, new flow regimes may occur in which the spatial distribution of the phases reflects the absence of a gravitational force. Therefore, to exploit the attractive advantages of multiphase systems under microgravity conditions, it is imperative to determine how they can be used and controlled in the absence of gravity.

It is recognized that there will probably be a continuing need for experimental microgravity data and appropriate empirical correlations, since some physical phenomena and HEDS design issues go beyond current, and anticipated near-term, computational capabilities. Nevertheless, the primary objective of the proposed research is the development of a reliable, physically based,2 multidimensional two-fluid model for the computational fluid dynamics (CFD) analysis of multiphase flow and heat transfer phenomena of importance to the HEDS program. Indeed, the following recommended research is aimed at developing predictive models of multiphase flow and heat transfer and testing these models against reduced-scale data taken in microgravity environments:

  • The development of physically based models to predict the flow regimes, flow regime transitions, and the multiphase flow and heat transfer that occur in fractional gravity and microgravity environments. These models should include the effects of two-phase turbulence, surface-tension-induced forces, and the axial and lateral interfacial and wall forces on the flowing phases (i.e., the flow-regime-specific interfacial and wall constitutive laws). They should be suitable for use in three-dimensional CFD solvers.

  • Assessment of the predictive capabilities of these models by comparing them with the results of reducedscale and separate-effects experiments performed under microgravity conditions. In particular, detailed data are needed on flow-regime-specific phenomena in complex geometry conduits (where gravity dependence may occur even at high flow rates); the distribution and separation of the phases for the various flow regimes, including the effect of phase separations induced by swirl; and the local velocity temperature, void fraction, and turbulence fields.

  • A program parallel to the one described above for assessing the effect of gravity level on forced convective flows, especially the forced-flow boiling curve for different boiling regimes (e.g., nucleate and film). Such a program is essential, since forced flow can compensate for some of the problems arising from the loss of buoyancy.

Multiphase System Dynamics

In systems using multiphase flow, effects on a global scale may emerge from the interaction of the components. In particular, phase or time lags in feedback loops can cause potentially dangerous instabilities that are revealed only by analysis of the system as a whole. The following research is recommended:

  • The development of models and the collection and analysis of stability data on boiling and condensing systems at fractional gravity and microgravity levels. In particular, the effect of gravity level on excursive instabilities, as well as on those dynamic instabilities that can be induced by compressibility and lags in the propagation of density waves around closed loops in multiphase systems, needs to be investigated and analyzed.

2  

In the context of this report, a physically based model is one that is developed from fundamental principles and physical mechanisms, as opposed to an empirical model. See the glossary, Appendix C.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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Fire Phenomena

Accidental fires are a major hazard in the confined quarters of spacecraft. The structure and dynamics of fires and flames are drastically altered in microgravity, primarily because there is no buoyancy-driven convection or sedimentation (e.g., of smoke particles). Accordingly, the following research is recommended:

  • Experimental, theoretical, and computational studies of flame spread over surfaces of solid materials in microgravity and fractional gravity. These studies should focus on generic materials, both cellulose and synthetic polymers, and should include ignition requirements, flame-spread rates, and flame structure. Parallel studies on the production of gaseous fuel from solid-fuel pyrolysis are needed.

  • Gravity effects in smoldering, as in the case of electrical cable fires. In particular, the research should look at the initiation and termination of smoldering, propagation rates of smoldering fronts, and the production of hazardous or flammable products from smoldering, including conditions for transition from smoldering to flaming combustion.

Granular Mechanics

The granular materials encountered in lunar and Martian soils will serve both as the physical foundation that supports people, equipment, and buildings and as a raw material to be mined and used for construction and for the extraction of valuable resources. Granular material in the form of dust is expected to be a serious environmental problem on the Moon and Mars. The behavior of granular materials in response to loads and digging, and flowing in chutes and hoppers, or in atmospheric transport (i.e., dust) and adhesion to surfaces, is affected by gravity level. Accordingly, the following research is recommended:

  • The response of granular material to applied stress. The knowledge gained will allow researchers to examine separately the effects of gravity and shearing using both analytical and experimental studies. Predictive models of granular deformation and flow under reduced gravity need to be developed that include the effects of particle size and shape, the effects of particle constitution, and the effects of particle agitation and of electrostatic charge, especially at low pressures.

  • Predictive models of the behavior of dust in spacecraft and extraterrestrial environments. An understanding of this behavior will permit the reliable prediction of dust transport and deposition. An understanding is also needed of the cohesion and adhesion mechanisms that control dust attachment, where the attraction mechanism appears to be electrostatic.

OTHER CONCERNS
Reduced-Gravity Countermeasures

Because reduced or variable gravity is generally a troublesome complication of system design for HEDS (and has harmful consequences for human health), research should be carried out on means to counter the adverse effects. Such means would probably be mechanical in nature, involving rotation or vibration, and could be implemented at a range of levels, from that of the whole spacecraft down to the level of small but critical components. Design studies of structural and system problems would be required to establish technical practicality and costs for large-scale artificial-gravity concepts.

Applied research looking toward economic and effective artificial gravity should emphasize solutions that would apply to both technical and biological systems.

Research on and development of reduced-gravity countermeasures are given higher priority in the report and must obviously proceed hand in hand with the microgravity research recommended elsewhere in this report, because the latter will establish the target gravity levels desired for various components and systems. In turn, the specific benefits of an artificial gravity system must be understood and weighed against the penalties (e.g., weight and cost) so that design trade-offs can be made. In other words, it is to be expected that artificial gravity will be part of integrated system designs for HEDS.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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Indirect Effects of Reduced Gravity

Reduced gravity will have indirect effects on systems and components, necessitating designs different from the corresponding, more familiar ones on Earth. For example, seemingly mundane components such as piping, valves, and bearings will have to be adapted to the altered structural forces and loads in reduced- and variable-gravity environments. Then, too, products of wear and decay are presumably less easily managed in microgravity. Such concerns are additional elements in a central HEDS issue, namely the effect of reduced and variable gravity on system reliability and safety.

RECOMMENDED RESEARCH WITH A LOWER PRIORITY

The committee also recommends research on other fundamental phenomena in addition to those described above. These phenomena, listed below in no particular order, were judged to be somewhat less critical to mission success, so the research has a lower priority.

  • Marangoni material parameters;

  • Static equilibrium capillary shapes;

  • The effect of gravity on convective condensation heat transfer;

  • The effect of gravity on the heat transfer characteristics of fluid flow in porous media;

  • The transport of flame suppressant to fires in reduced gravity;

  • Diffusion-flame structure of fuels and flame products as affected by gravity levels;

  • Flammability and flame behavior of gaseous combustible mixtures, sprays, and dust clouds; and

  • The effect of gravity on nucleation and growth of solid from the melt.

PROGRAMMATIC RECOMMENDATIONS

It should be clearly understood that the committee's research recommendations deal with fundamental phenomena associated with fluid and material behavior rather than with the direct development of subsystems and their integration into technologies operable in a reduced-gravity environment. However, the committee recognizes that blending conceptual design needs and phenomenological research findings requires a great deal of communication, coordination, and interdisciplinary collaboration among designers and researchers. For this reason, it makes recommendations in this report concerning the goals, research planning, and programmatic activities of NASA that support gravity-related research for HEDS. Similar recommendations made in the phase I report (NRC, 1997) are reflected in this more extensive study as well. It was thought then, and is still believed, that in view of the long time scale needed for the evolution of basic scientific concepts into practical applications, the suggested research programs will require a sustained commitment on the part of NASA to achieve an understanding of gravity-related issues.

A Research Approach for the Development of Multiphase Flow and Heat Transfer Technology

For NASA to be able to decide whether multiphase and phase change systems can be used and controlled in future HEDS missions, a well-focused experimental and analytical research program will be needed to develop an understanding of how multiphase systems and processes behave in reduced gravity. Since parametric full-scale testing in space is not feasible, NASA should consider developing a reliable three-dimensional, two-fluid CFD model that can be used to help design and analyze multiphase systems and subsystems for HEDS missions. The approach that has been recommended is that a reliable, physically based analytical model be developed and qualified against appropriate terrestrial and microgravity data. The resulting computational model could then be used to analyze and optimize final designs and to scale up the reduced-scale data obtained in space. While this is expected to be the most reliable, least expensive, and quickest means of developing the potentially enabling technology required by HEDS, programmatic changes would be required to accomplish this goal. In particular, it would be necessary for NASA to refocus its multiphase fluid physics research program and to be much more proactive than it has been in defining and managing the research needed to develop predictive capabilities for multiphase flow and heat transfer. In this context, NASA should investigate the possibility of consulting the U.S.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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Department of Energy-Naval Reactors program for help in designing research programs aimed at developing the required multivariate, physically based computational models.

Coordination of Research and Design

The NASA office responsible for microgravity research should diligently inform NASA at large about the issues of reduced gravity that are foreseen for space hardware design, so that such considerations may enter design thinking at the concept stage. It should also apprise the microgravity research community of design issues relevant to microgravity research, and NASA should encourage the blending of conceptual design and phenomenological research. This will require active communication and coordination among basic researchers and system designers and users, which should be specifically encouraged by such means as regular workshops and study groups in which both mission technologists and microgravity scientists participate.

Microgravity Research and the International Space Station

It is expected that the International Space Station (ISS) will provide a unique platform for conducting long-duration microgravity scientific research and assessing the efficiency and long-term suitability of many of the technical systems important to HEDS. The committee reiterates a recommendation from its phase I report (NRC, 1997, p. 39): In addition to carrying out basic research aboard the ISS, NASA should take advantage of the station and its subsystems, using them for testbed studies of scientific and engineering concepts applicable to HEDS technologies. In particular, the ISS can play an important role in the multiphase flow and heat transfer research program recommended above.

Peer Review for Reduced-Gravity Research

The NASA Research Announcement process and its peer review system have greatly enhanced the productivity and quality of NASA's gravity-related research. These mechanisms should be maintained as steps are taken to develop areas of science affecting HEDS technologies.

REFERENCE

National Research Council (NRC), Space Studies Board. 1997. An Initial Review of Microgravity Research in Support of Human Exploration and Development of Space. Washington, D.C.: National Academy Press.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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3.5 Preventing the Forward Contamination of Europa

A Report of the Task Group on the Forward Contamination of Europa

Executive Summary

Planetary protection is an essential consideration for exploration of planets or satellites that may have experienced prebiotic chemical evolution or that may have developed life. Recent observations of Jupiter's satellite Europa indicate that it has been geologically active in the relatively recent past and that liquid water might exist beneath a surface ice shell some 10 to 170 km thick. Moreover, water might exist closer to the surface on an intermittent basis if the ice shell is cracked or otherwise punctured owing to the action of internal and external forces.

We know that life arose rapidly on Earth, perhaps in ancient hydrothermal systems. In these systems, cold ocean water is taken up and circulated through a geothermally heated zone, where it interacts chemically with minerals, and is then released back into the ocean. Its high temperature and dissolved mineral content result in a state of physical and chemical disequilibrium when it mixes again with the cold water. On Earth, the subsequent reactions to reestablish equilibrium were able to provide energy to support metabolism. Europa may also have such geothermal zones if a global ocean of liquid water exists below the surface.

Terrestrial microorganisms provide the only available reference point for evaluating whether life might already be present on Europa or whether it could be introduced by a contaminated spacecraft. On Earth, life is found in some of the most extreme environments. These include extreme heat, cold, pressure, salinity, acidity, dryness, and radiation. Microorganisms are remarkably resilient and have survived exposure to the space environment for more than 5 years aboard the Long Duration Exposure Facility and for millions of years in permafrost regions on Earth's surface. Moreover, in some circumstances, the ability to survive one form of environmental stress may confer the ability to survive in another stressful environment. Many common bacteria are, for example, desiccation resistant, and there is evidence suggesting that the mechanisms that evolved to permit survival in very dry regions also confer resistance to irradiation. Organisms capable of surviving a particular set of extreme conditions cannot, therefore, be assumed to be necessarily confined to environments possessing those conditions.

Even though current information is not sufficient to conclude whether Europa has an ocean, native life, or environments compatible with terrestrial life, it is also insufficient to dismiss these possibilities at this time. Thus, future spacecraft missions to Europa must be subject to procedures designed to prevent its contamination by terrestrial organisms. This is necessary to safeguard the scientific integrity of future studies of Europa's biological potential and to protect against potential harm to europan organisms, if they exist, and is mandated by obligations under the United Nations' Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies (U.N. Document No. 6347 January 1967).

Current NASA requirements for the protection of other planetary environments are based on categorizing the mission as to type and the target object as to its likelihood of harboring life. The current procedures for planetary protection use protocols derived from those originally developed for the Viking missions to Mars in the 1970s. Determining whether or not this methodology is applicable to Europa missions was the central facet of the task group's deliberations.

The Task Group on the Forward Contamination of Europa concluded that current cleaning and sterilization techniques are satisfactory to meet the needs of future space missions to Europa. These techniques include Viking-derived procedures such as cleaning surfaces with isopropyl alcohol and/or sporicides and sterilization by dry heating, as well as more modern processes such as sterilization by hydrogen peroxide, assuming that final sterilization is accomplished via exposure of the spacecraft to Europa's radiation environment. The technological drawbacks of current prelaunch sterilization techniques are such that the use of such techniques is likely to increase the complexity and, hence, the cost of a mission.

The task group also concluded that the current spore-based culturing techniques used to determine the bioload on a spacecraft should be supplemented by screening tests for specific types of extremophiles, such as radiation-

NOTE: "Executive Summary" reprinted from Preventing the Forward Contamination of Europa, National Academy Press,Washington, D.C., 2000, pp. 1-2.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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resistant organisms. In addition, modern molecular methods, such as those based on the polymerase chain reaction (PCR), may prove to be quicker and more sensitive for detecting and identifying biological contamination than NASA's existing culturing protocols for planetary protection.

The task group recommends a number of studies that would improve knowledge of Europa and that would better define the issues related to minimization of forward contamination. These include studies on the following topics:

  • Ecology of clean room and spacecraft-assembly areas, with emphasis on extremophiles such as radiation-resistant microbes;

  • Detailed comparisons of bioload assay methods;

  • Desiccation- and radiation-resistant microbes that may contaminate spacecraft during assembly;

  • Autotroph detection techniques; and

  • Europa's surface environment and its hydrologic and tectonic cycles.

The task group was unable to reach complete agreement on the central issue of the planetary protection standards that must be met by future missions to Europa. The majority of its members believe that Europa 's potential importance to studies of chemical evolution and the origin of life is great but that detailed understanding of the europan environment and the survival of terrestrial organisms in extreme conditions is so limited that the current planetary protection methodology is not readily applicable to Europa missions. Uncertainties demand conservatism, and, thus, the very first mission to Europa must meet the highest reasonable level of safeguard.

In practice, this means that the bioload of each Europa-bound spacecraft must be reduced to a sufficiently low level at launch that delivery of a viable organism to a subsurface ocean is precluded at a high level of probability. This approach allows mission planners to take advantage of the bioload reduction likely to occur en route, particularly while in Jupiter's radiation environment. One consequence of this view is that Europa must be protected from contamination for an open-ended period, until it can be demonstrated that no ocean exists or that no organisms are present. Thus, we need to be concerned that over a time scale on the order of 10 million to 100 million years (an approximate age for the surface of Europa), any contaminating material is likely to be carried into the deep ice crust or into the underlying ocean.

Thus, the task group's majority concluded that spacecraft sent to Europa must have their bioload at launch reduced to such a level that, taking into account the natural additional reduction that occurs after launch, the probability of contaminating a europan ocean with a viable terrestrial organism at any time in the future should be less than 10−4 per mission. How this standard might be implemented by a combination of Viking-level cleaning and sterilization, accompanied by bioload reduction in the europan radiation environment, is illustrated by a probabilistic calculation offered by the task group (Appendix A).

In addition to the majority view, this report presents two independent minority viewpoints that argue for less stringent planetary protection requirements.1

1  

The minority viewpoints supporting less-stringent planetary protection procedures than those advocated by the majority are based on two independent arguments. One subset of the task group argued that the planetary protection provisions for Europa should be broadly consistent with the current policies, practices, and protocols. The other subset argued that studies of the organisms found in extreme terrestrial environments suggest that no known terrestrial organism has a significant probability of surviving and multiplying in a europan ocean. The practical consequences of both of these views is that Europa missions should be subject to essentially the same planetary protection requirements that are currently applied to Mars missions. That is, spacecraft (including orbiters) without biological experiments should be subject to at least Viking-level cleaning, but sterilization is not necessary.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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3.6 Astronomy and Astrophysics in the New Millennium

A Report of the Astronomy and Astrophysics Survey Committee, under the Board on Physics and Astronomy with the assistance of the Space Studies Board

Executive Summary
ASTRONOMY AND ASTROPHYSICS IN THE NEW MILLENNIUM

In the first decade of the new millennium, we are poised to take a giant step forward in understanding the universe and our place within it. The decade of the 1990s saw an enormous number of exciting discoveries in astronomy and astrophysics. For example, humanity 's centuries-long quest for evidence of the existence of planets around other stars resulted in the discovery of extrasolar planets, and the number of planets known continues to grow. Astronomers peered far back in time, to only a few hundred thousand years after the Big Bang, and found the seeds from which all galaxies, such as our own Milky Way, were formed. At the end of the decade came evidence for a new form of energy that may pervade the universe. Nearby galaxies were found to harbor extremely massive black holes in their centers. Distant galaxies were discovered near the edge of the visible universe. In our own solar system, the discovery of Kuiper Belt objects—some of which lie beyond the orbit of Pluto—opens a new window onto the history of the solar system. This report presents a comprehensive and prioritized plan for the new decade that builds on these and other discoveries to pursue the goal of understanding the universe, a goal that unites astronomers and astrophysicists with scientists from many other disciplines.

The Astronomy and Astrophysics Survey Committee was charged with surveying both ground- and spacebased astronomy and recommending priorities for new initiatives in the decade 2000 to 2010. In addition, the committee was asked to consider the effective implementation of both the proposed initiatives and the existing programs. The committee 's charge excludes in situ studies of Earth and the planets, which are covered by other National Research Council committees: the Committee on Planetary and Lunar Exploration and the Committee on Solar and Space Physics. To carry out its mandate, the committee established nine panels with more than 100 distinguished members of the astronomical community. Broad input was sought through the panels, in forums held by the American Astronomical Society, and in meetings with representatives of the international astronomical community. The committee's recommendations build on those of four previous decadal surveys (NRC, 1964, 1972, 1982, 1991), in particular the report of the 1991 Astronomy and Astrophysics Survey Committee, The Decade of Discovery in Astronomy and Astrophysics (referred to in this report as the 1991 survey, also known as the Bahcall report).

The fundamental goal of astronomy and astrophysics is to understand how the universe and its constituent galaxies, stars, and planets formed, how they evolved, and what their destiny will be. To achieve this goal, researchers must pursue a strategy with several elements:

  • Survey the universe and its constituents, including galaxies as they evolve through cosmic time, stars and planets as they form out of collapsing interstellar clouds in the galaxy, interstellar and intergalactic gas as it accumulates the elements created in stars and supernovae, and the mysterious dark matter and perhaps dark energy that so strongly influence the large-scale structure and dynamics of the universe.

  • Use the universe as a unique laboratory for probing the laws of physics in regimes not accessible on Earth, such as the very early universe or near the event horizon of a black hole.

  • Search for life beyond the Earth, and if it is found, determine its nature and its distribution.

  • Develop a conceptual framework that accounts for all that astronomers have observed.

Several key problems are particularly ripe for advances in the coming decade:

  • Determine the large-scale properties of the universe: the amount, distribution, and nature of its matter and energy, its age, and the history of its expansion.

NOTE: "Executive Summary" reprinted from Astronomy and Astrophysics in the New Millennium, National Academy Press,Washington, D.C., 2000, pp. 1-15, plus relevant references extracted from pp. 210-211.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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  • Study the dawn of the modern universe, when the first stars and galaxies formed.

  • Understand the formation and evolution of black holes of all sizes.

  • Study the formation of stars and their planetary systems, and the birth and evolution of giant and terrestrial planets.

  • Understand how the astronomical environment affects Earth.

These scientific themes, all of which now appear to offer particular promise for immediate progress, are only part of the much larger tapestry that is modern astronomy and astrophysics. For example, scientists cannot hope to understand the formation of black holes without understanding the late stages of stellar evolution, and the full significance of observations of the galaxies in the very early universe will not be clear until it is clear how these galaxies have evolved since that time. Although the new initiatives that the committee recommends will advance knowledge in many other areas as well, they were selected explicitly to address one or more of the important themes listed above.

In addition, the committee believes that astronomers can make important contributions to education. Building on widespread interest in astronomical discoveries, astronomers should

  • Use astronomy as a gateway to enhance the public's understanding of science and as a catalyst to improve teachers' education in science and to advance interdisciplinary training of the technical work force.

OPTIMIZING THE RETURN ON THE NATION'S INVESTMENT IN ASTRONOMY AND ASTROPHYSICS

The United States has been generous in its support of astronomy and astrophysics and as a result enjoys a leading role in almost all areas of astronomy and astrophysics. So that the nation can continue to obtain maximum scientific return on its investment, the committee makes several recommendations to optimize the system of support for astronomical research.

Balancing New Initiatives with the Ongoing Program

An effective program of astronomy and astrophysics research must balance the need for initiatives to address new opportunities with completion of projects accorded high scientific priority in previous surveys.

  • The committee reaffirms the recommendations of the 1991 Astronomy and Astrophysics Survey Committee (NRC, 1991) by endorsing the completion of the Space Infrared Telescope Facility (SIRTF), the Millimeter Array (MMA; now part of the Atacama Large Millimeter Array, or ALMA), the Stratospheric Observatory for Infrared Astronomy (SOFIA), and the Astrometric Interferometry Mission (now called the Space Interferometry Mission, or SIM). Consistent with the recommendations of the Task Group on Space Astronomy and Astrophysics (NRC, 1997), the committee stresses the importance of studying the cosmic microwave background with the Microwave Anisotropy Probe (MAP) mission, the European Planck Surveyor mission, and ground-based and balloon programs.

The committee endorses U.S. participation in the European Far Infrared Space Telescope (FIRST), and it endorses the planned continuation of the operation of the Hubble Space Telescope (HST) at a reduced cost until the end of the decade.

  • To achieve the full scientific potential of a new facility, it is essential that, prior to construction, funds be identified for operation of the facility, for renewal of its instrumentation, and for grants for data analysis and the development of associated theory.

NASA already follows this recommendation in large part by including Mission Operations and Data Analysis (MO&DA) in its budgeting for new missions. The committee recommends that funds for associated theory be included in MO&DA as well. It recommends further that the National Science Foundation include funds for facility operation, renewal of instrumentation, and grants for data analysis and theory along with the construction costs in

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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the budgets for all new federally funded, ground-based facilities. These recommendations are consistent with those of the 1991 survey. For the purpose of total project budget estimation, the committee adopted a model in which operation amounts to 7 percent of the capital cost per year and instrumentation amounts to 3 percent per year for the first 5 years of operation. The committee recommends that total project budgets provide for grants for data analysis and associated theory at the rate of 3 percent of the capital cost per year for major facilities and 5 percent per year for moderate ones. On the basis of this model, the committee has included funds for operations, instrumentation, and grants for a period of 5 years in the cost estimates provided in this report for most ground-based initiatives.

  • Adequate funding for unrestricted grants that provides broad support for research, students, and postdoctoral associates is required to ensure the future vitality of the field; therefore new initiatives should not be undertaken at the expense of the unrestricted grants program.

Grants not tied to a facility or program—unrestricted grants—often drive the future directions of astronomy.

Strengthening Ground-Based Astronomy and Astrophysics

The committee addresses several structural issues in ground-based astronomy and astrophysics.

  • U.S. ground-based optical-infrared facilities, radio facilities, and solar facilities should each be viewed by the National Science Foundation (NSF) and the astronomical community as a single integrated system drawing on both federal and nonfederal funding sources. Effective national organizations are essential to coordinate, and to ensure the success and efficiency of, these systems. Universities and independent observatories should work with the national organizations to ensure the success of these systems.

  • Cross-disciplinary competitive reviews should be held about every 5 years for all NSF astronomy facilities. In these reviews, it should be standard policy to set priorities and consider possible closure or privatization.

The National Radio Astronomy Observatory (NRAO) and the National Astronomy and Ionosphere Center (NAIC) currently serve as effective national organizations for radio astronomy, and the National Solar Observatory (NSO) does so for solar physics. The National Optical Astronomy Observatories (NOAO) as currently functioning and overseen does not fulfill this role for ground-based optical and infrared astronomy. A plan for the transition of NOAO to an effective national organization for ground-based optical and infrared astronomy should be developed, and a high-level external review, based on appropriate, explicit criteria, should be initiated.

The Department of Energy (DOE) supports a broad range of programs in particle and nuclear astrophysics and in cosmology. The scientific payoff of this effort would be even stronger with a clearly articulated strategic plan for DOE's programs that involve astrophysics.

  • Given the increasing involvement of the Department of Energy in projects that involve astrophysics, the committee recommends that DOE develop a strategic plan for astrophysics that would lend programmatic coherence and facilitate coordination and cooperation with other agencies on science of mutual interest.

Ensuring the Diversity of NASA Missions

NASA's Great Observatories have revolutionized understanding of the cosmos, while the extremely successful Explorer program provides targeted small-mission opportunities for advances in many areas of astronomy and astrophysics. The committee endorses the continuation of a vigorous Explorer program. There are now fewer opportunities for missions of moderate size, however, despite the enormous role such missions have played in the past.

  • NASA should continue to encourage the development of a diverse range of mission sizes, including small, moderate, and major, to ensure the most effective returns from the U.S. space program.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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Integrating Theory Challenges into the New Initiatives

The new initiatives recommended below are motivated in large part by theory, which is also key to interpreting the results. Adequate support for theory, including numerical simulation, is a cost-effective means for maximizing the impact of the nation's investment in science facilities. The committee therefore recommends that

  • To encourage theorists to contribute to the planning of missions and facilities and to the interpretation and understanding of the results, one or more explicitly funded theory challenges should be integrated with most moderate or major new initiatives.

Coordinating Programs Among Federal Agencies

Because of the enormous scale of contemporary astronomical projects and because of the need for investigations that cross wavelength and discipline boundaries, cooperation among the federal agencies that support astronomical research often has benefits. To determine when interagency collaboration would be fruitful, each agency should have in place a strategic plan for astronomy and astrophysics and should also have cross-disciplinary committees (such as DOE and NSF 's Scientific Assessment Group for Experiments in Non-Accelerator Physics [SAGENAP] and NASA's Space Science Advisory Committee [SSAC]) available to evaluate proposed collaborations. The Office of Science and Technology Policy could play a useful role in facilitating such interagency cooperation.

Collaborating with International Partners

International collaboration enables projects that are too costly for the United States alone and enhances the scientific return on projects by bringing in the scientific and technical expertise of international partners. In many cases, international collaboration provides opportunities for U.S. astronomers to participate in major international projects for a fraction of the total cost, as in the case of the European Solar and Heliospheric Observatory (SOHO), XMM-Newton, Planck Surveyor and FIRST missions, and the Japanese Advanced Satellite for Cosmology and Astrophysics mission. Valuable opportunities for international collaboration exist for smaller missions as well. Collaborations on major projects require the full support of the participating scientific communities, which can be ensured if the projects are among the very highest priorities of the participants, as is the case with ALMA.

The committee affirms the value of international collaboration for ground-based and space-based projects of all sizes. International collaboration plays a crucial role in a number of this committee 's recommended initiatives, including the Next Generation Space Telescope, the Expanded Very Large Array, the Gamma-ray Large Area Space Telescope, the Laser Interferometer Space Antenna, the Advanced Solar Telescope, and the Square Kilometer Array technology development, and it could play a significant role in other recommended initiatives as well.

NEW INVESTMENTS IN ASTRONOMY AND ASTROPHYSICS

Many mysteries confront us in the quest to understand our place in the universe. How did the universe begin? What is the nature of the dark matter and the dark energy that pervade the universe? How did the first stars and galaxies form? Researchers infer the existence of stellar mass black holes in our Galaxy and supermassive ones in the nuclei of galaxies. How did they form? The discovery of extrasolar planets has opened an entirely new chapter in astronomy, bringing a host of unresolved questions. How do planetary systems form and evolve? Are planetary systems like our solar system common in the universe? Do any extrasolar planetary systems harbor life? Even a familiar object like the Sun poses many mysteries. What causes the small variations in the Sun's luminosity that can affect Earth's climate? What is the origin of the eruptions on the solar surface that cause “space weather”?

To seek the answers to these questions and many others described in this report, the committee recommends a set of new initiatives for this decade that will substantially advance the frontiers of human knowledge. Table ES.1 presents these initiatives, combined for both ground- and space-based astronomy, in order of priority. The committee set the priorities primarily on the basis of scientific merit, but it also considered technical readiness, cost-effectiveness, impact on education and public outreach, and the relation to other projects. The initiatives were divided into three categories—major, moderate, and small—that were defined separately for ground- and space-

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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TABLE ES. 1 Prioritized Equipment Initiatives (Combined Ground and Space) and Estimated Federal Costs for the Decade 2000 to 2010a,b

Initiative

Costc ($M)

Major Initiatives

Next Generation Space Telescope (NGST)d

1,000

Giant Segmented-Mirror Telescope (GSMT)d

350

Constellation-X Observatory (CON-X)

800

Expanded Very Large Array (EVLA)d

140

Large- aperture Synoptic Survey Telescope (LSST)

170

Terrestrial Planet Finder (TPF)e

200

Single-Aperture Far Infrared (SAFIR) Observatorye

100

Subtotal for major initiatives

2,760

Moderate Initiatives

Telescope System Instrumentation Program (TSIP)

50

Gamma-ray Large Area Space Telescope (GLAST)d

300

Laser Interferometer Space Antenna (LISA)d

250

Advanced Solar Telescope (AST)d

60

Square Kilometer Array (SKA) Technology Development

22

Solar Dynamics Observer (SDO)

300

Combined Array for Research in Millimeter-wave Astronomy (CARMA)d

11

Energetic X-ray Imaging Survey Telescope (EXIST)

150

Very Energetic Radiation Imaging Telescope Array System (VERITAS)

35

Advanced Radio Interferometry between Space and Earth (ARISE)

350

Frequency Agile Solar Radio telescope (FASR)

26

South Pole Submillimeter-wave Telescope (SPST)

50

Subtotal for moderate initiatives

1,604

Small Initiatives

National Virtual Observatory (NVO)

60

Other small initiativesf

246

Subtotal for small initiatives

306

DECADE TOTAL

4,670

aCost estimates for ground-based capital projects include technology development plus funds for operations, new instrumentation, and facility grants for 5 years.

bCost estimates for space-based projects exclude technology development.

cBest available estimated costs to U.S. government agencies in millions of FY2000 dollars and rounded. Full costs are given for all initiatives except TPF and the SAFIR Observatory.

dCost estimate for this initiative assumes significant additional funding to be provided by international or private partner; see Astronomy and Astrophysics in the New Millennium: Panel Reports (NRC, 2001) for details.

eThese missions could start at the turn of the decade. The committee attributes $200 million of the $1,700 million total estimated cost of TPF to the current decade and $100 million of the $600 million total estimated cost of the SAFIR Observatory to the current decade.

fSee Chapter 1 for details.

based projects based on the estimated cost (see Chapter 1). The estimated cost of the recommended program for the decade 2000 to 2010 is $4.7 billion in FY2000 dollars, about 20 percent greater than the $3.9 billion inflation-adjusted cost of the recommendations of the 1991 survey. Two of the recommended projects, the Terrestrial Planet Finder (TPF) and the Single-Aperture Far-Infrared (SAFIR) Observatory, could start near the end of this decade or at the beginning of the next. The committee has assumed that about 15 percent of the total estimated cost for these two projects will fall in this decade.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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Major Initiatives
  • The Next Generation Space Telescope (NGST), the committee's top-priority recommendation, is designed to detect light from the first stars and to trace the evolution of galaxies from their formation to the present. It will revolutionize understanding of how stars and planets form in the Galaxy today. NGST is an 8-m-class infrared space telescope with 100 times the sensitivity and 10 times the image sharpness of the Hubble Space Telescope in the infrared. Having NGST 's sensitivity extend to 27 m would add significantly to its scientific return. Technology development for this program is well under way. The European Space Agency and the Canadian Space Agency plan to make substantial contributions to the instrumentation for NGST.

  • The Giant Segmented Mirror Telescope (GSMT), the committee's top ground-based recommendation and second priority overall, is a 30-m-class ground-based telescope that will be a powerful complement to NGST in tracing the evolution of galaxies and the formation of stars and planets. It will have unique capabilities in studying the evolution of the intergalactic medium and the history of star formation in the Galaxy and its nearest neighbors. GSMT will use adaptive optics to achieve diffraction-limited imaging in the atmospheric windows between 1 and 25 m and unprecedented light-gathering power between 0.3 and 1 m. The committee recommends that the technology development for GSMT begin immediately and that construction start within the decade. Half the total cost should come from private and/or international partners. Open access to the GSMT by the U.S. astronomical community should be directly proportional to the investment by the NSF.

  • The Constellation-X Observatory is a suite of four powerful x-ray telescopes in space that will become the premier instrument for studying the formation and evolution of black holes of all sizes. Each telescope will have high spectral resolution over a broad energy range, enabling it to study quasars near the edge of the visible universe and to trace the evolution of the chemical elements. The technology issues are well in hand for a start in the middle of this decade.

  • The Expanded Very Large Array (EVLA)—the revitalization of the VLA, the world's foremost centimeter-wave radio telescope—will take advantage of modern technology to attain unprecedented image quality with 10 times the sensitivity and 1,000 times the spectroscopic capability of the existing VLA. The addition of eight new antennas will provide an order-of-magnitude increase in angular resolution. With resolution comparable to that of ALMA and NGST, but operating at much longer wavelengths, the EVLA will be a powerful complement to these instruments for studying the formation of protoplanetary disks and the earliest stages of galaxy formation.

  • The Large-aperture Synoptic Survey Telescope (LSST) is a 6.5-m-class optical telescope designed to survey the visible sky every week down to a much fainter level than that reached by existing surveys. It will catalog 90 percent of the near-Earth objects larger than 300 m and assess the threat they pose to life on Earth. It will find some 10,000 primitive objects in the Kuiper Belt, which contains a fossil record of the formation of the solar system. It will also contribute to the study of the structure of the universe by observing thousands of supernovae, both nearby and at large redshift, and by measuring the distribution of dark matter through gravitational lensing. All the data will be available through the National Virtual Observatory (see below under “ Small Initiatives ”), providing access for astronomers and the public to very deep images of the changing night sky.

  • The Terrestrial Planet Finder (TPF) is the most ambitious science mission ever attempted by NASA. It is a free-flying infrared interferometer designed to study terrestrial planets around nearby stars—to find them, characterize their atmospheres, and search for evidence of life—and to obtain images of star-forming regions and distant galaxies with unprecedented resolution. The committee 's recommendation of this mission is predicated on the assumptions that TPF will revolutionize major areas of both planetary and nonplanetary science, and that, prior to the start of TPF, ground- and space-based searches will confirm the expectation that terrestrial planets are common around solar-type stars. Both NGST and SIM lie on the technology path necessary to achieve TPF.

  • The Single-Aperture Far-Infrared (SAFIR) Observatory is an 8-m-class space-based telescope that will study the important and relatively unexplored spectral region between 30 and 300 mm. It will enable the study of galaxy formation and the earliest stage of star formation by revealing regions too enshrouded by dust to be studied by NGST, and too warm to be studied effectively with ALMA. As a follow-on to NGST, SAFIR could start toward the end of the decade, and it could form the basis for developing a far-infrared interferometer in the succeeding decade.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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Moderate Initiatives
Ground-Based Programs

The committee's recommended highest-priority moderate initiative overall is the Telescope System Instrumentation Program (TSIP), which would substantially increase NSF funding for instrumentation at large telescopes owned by independent observatories and provide new observing opportunities for the entire U.S. astronomical community. Its second priority among ground-based initiatives is the Advanced Solar Telescope (AST), which offers the prospect of revolutionizing understanding of magnetic phenomena in the Sun and in the rest of the universe. The committee 's next recommendation is that a program be established to plan and develop technology for the Square Kilometer Array, an international centimeter-wave radio telescope for the second decade of the century. In order of priority, the other recommended moderate initiatives are the following: The Combined Array for Research in Millimeter-wave Astronomy (CARMA) will be a powerful millimeter-wave array in the Northern Hemisphere. The study of very-high-energy gamma rays will take a major step forward with the construction of the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The Frequency Agile Solar Radio telescope (FASR) will apply modern technology to provide unique data on the Sun at radio wavelengths. The South Pole Submillimeter-wave Telescope (SPST) will take advantage of the extremely low opacity of the Antarctic atmosphere to carry out surveys at submillimeter wavelengths that are possible nowhere else on Earth.

Space-Based Programs

The committee's top recommendation for a moderate space-based mission is the Gamma-ray Large Area Space Telescope (GLAST). This joint NASA-DOE mission will provide observations of gamma rays from 10 MeV to 300 GeV with six times the effective area, six times the field of view, and substantially better angular resolution than the Energetic Gamma Ray Experiment aboard the Compton Gamma Ray Observatory. The committee's second-priority space-based project is the Laser Interferometer Space Antenna (LISA), which will be able to detect gravity waves from merging supermassive black holes throughout the visible universe and from close binary stars throughout the Galaxy. The committee has assumed that LISA 'S cost will be shared with the European Space Agency. Four additional space-based missions have priority. The Solar Dynamics Observer (SDO), a successor to the pathbreaking SOHO mission, will study the outer convective zone of the Sun and the structure of the solar corona. The highly variable hard x-ray sky will be mapped by the Energetic X-ray Imaging Survey Telescope (EXIST), which will be attached to the International Space Station. The Advanced Radio Interferometry between Space and Earth (ARISE) mission is an orbiting antenna that will combine with the ground-based VLBA to provide an order-of-magnitude increase in resolution for studying the regions near supermassive black holes in active galactic nuclei.

Small Initiatives

Several small initiatives recommended by the committee span both ground and space. The first among them—the National Virtual Observatory (NVO)—is the committee's top priority among the small initiatives. The NVO will provide a “virtual sky” based on the enormous data sets being created now and the even larger ones proposed for the future. It will enable a new mode of research for professional astronomers and will provide to the public an unparalleled opportunity for education and discovery.

The remaining recommendations for small initiatives are not prioritized. The committee recommends establishing a laboratory astrophysics program and a national astrophysical theory postdoctoral program for both ground- and space-based endeavors. Augmentation of NASA's Astrophysics Theory Program will help restore a balance between the acquisition of data and the theory needed to interpret it. Ultra long-duration balloon flights offer the prospect of carrying out small space-based experiments at a small fraction of the cost of satellites. The Low Frequency Array (LOFAR), a joint Dutch-U.S. initiative, will dramatically increase knowledge of the universe at radio wavelengths longer than 2 m. The Advanced Cosmic-ray Composition Experiment for the Space Station (ACCESS) will address fundamental questions about the origin of cosmic rays. Expansion of the Synoptic Optical Long-term Investigation of the Sun (SOLIS) will permit investigation of the solar magnetic field over an entire solar cycle.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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Technology

Technological innovation has often enabled astronomical discovery. Advances in technology in this decade are a prerequisite for many of the initiatives recommended in this report as well as for initiatives in the next decade. For the recommended space-based initiatives, technology investment as specified in the existing NASA technology road map is an assumed prerequisite for the cost estimates given in Table ES.1. It is essential to maintain funding for these initiatives if NASA is to keep these missions on schedule and within budget. The committee endorses NASA's policy of completing a mission's technological development before starting the mission. The committee similarly endorses such a policy as the NSF is applying it to the design and development of ALMA.

For possible ground-based initiatives in the decade next 2010 to 2020, investment is required in very large, high-speed digital correlators; in infrared interferometry; and in specialized dark matter detectors. Future spacebased initiatives require investment in spacecraft communication and x-ray interferometry, as well as technology for the next-generation observatories. Such technology will include energy-resolving array detectors for optical, ultraviolet, and x-ray wavelengths; far-infrared array detectors; refrigerators; large, lightweight optics; and gamma-ray detectors.

ASTRONOMY'S ROLE IN EDUCATION

Because of its broad public appeal, astronomy has a unique role to play in education and public outreach. The committee recommends that the following steps be taken to exploit the potential of astronomy for enhancing education and public understanding of science:

  • Expand and improve the opportunities for astronomers to engage in outreach to the K-12 community.

  • Establish more pilot partnerships between departments of astronomy and education at a few universities to develop exemplary science courses for preservice teachers.

  • Improve communication, planning, and coordination among federal programs that fund educational initiatives in astronomy.

  • Increase investment toward improving public understanding of the achievements of all NSF-funded science and facilities, especially in the area of astronomy.

REFERENCES

National Research Council (NRC). 1964. Ground-based Astronomy: A Ten-Year Program. National Academy of Sciences, Washington, D.C.

National Research Council (NRC). 1972. Astronomy and Astrophysics for the 1970's. National Academy of Sciences, Washington, D.C.

National Research Council (NRC). 1982. Astronomy and Astrophysics for the 1980's. Volume I: Report of the Astronomy Survey Committee. National Academy Press, Washington, D.C.

National Research Council (NRC). 1991. The Decade of Discovery in Astronomy and Astrophysics. National Academy Press, Washington, D.C.

National Research Council (NRC). 1997. A New Science Strategy for Space Astronomy and Astrophysics. National Academy Press, Washington, D.C.

National Research Council (NRC). 2001. Astronomy and Astrophysics in the New Millennium: Panel Reports. National Academy Press, Washington, D.C.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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3.7 Ensuring the Climate Record from the NPP and NPOESS Meteorological Satellites

A Report of the Committee on Earth Studies

Executive Summary
INTRODUCTION

Researchers studying the issues surrounding global climate change have a particular need for the kind of repetitive, long-term, high-quality measurements that can be provided from the vantage point of space. Operational weather satellites provide perhaps the only means for securing these measurements. The next generation of operational sensing systems is currently being designed, and the National Polar-orbiting Operational Environmental Satellite System (NPOESS), scheduled for launch beginning in 2009, is an important component of this operational monitoring system. NPOESS is being developed with the goal of meeting the converged operational data needs of the National Oceanic and Atmospheric Administration (NOAA) and the Department of Defense (DOD), as well as some of the data needs of the National Aeronautics and Space Administration (NASA) Earth observation programs.

In a joint mission to facilitate the transition of appropriate “research” satellite measurements into the operational domain, NASA and the NPOESS Integrated Program Office (IPO) are developing the NPOESS Preparatory Project (NPP). NASA and NOAA are supporting the NPP as part of a program of risk reduction demonstration and validation for NPOESS sensors, algorithms, and processing. The NPP satellite, scheduled for launch in 2005, will include critical sensors that are planned for flights on NPOESS. In addition, the NPP mission is expected to provide an early test of space and ground segments for NPOESS.

The NPOESS IPO has begun working with the members of the climate research community to define operational climate measurement needs. The IPO has also begun to assess the implications of these needs for NPOESS instrument design. However, it is equally important to ensure that the data systems will meet climate research needs. At the request of NOAA and NASA, the Space Studies Board's Committee on Earth Studies conducted a short-duration study of issues related to ensuring the climate record from the planned NPP and NPOESS satellites (see Appendix A for a statement of task). This report presents the committee's recommendations; it draws heavily on background material presented at the 2-day workshop that the committee hosted on February 7-8, 2000, and on discussions during and after the workshop.1 It also draws on investigations by the committee for the two-part report Issues in the Integration of Research and Operational Satellite Systems for Climate Research.2

Climate Data Records

In briefings to the committee, NASA and NOAA officials acknowledged that there is no operational ground system infrastructure for U.S. climate data and services. The climate research community therefore requires satellite data from NPP and NPOESS that can be used to generate climate data records (CDRs), data whose quality is known quantitatively and for which temporal and spatial biases are minimized (or at least quantified). CDR production will require considerable scientific insight, including the blending of multiple data sources, error analyses, and access to raw data sets. Moreover, information on sensor design, operation, and calibration will also be necessary to develop a consistent CDR across multiple sensors.

NASA intends for environmental data records (EDRs)3 —the priority data products that will be produced from

  

NOTE: "Executive Summary" reprinted from Ensuring the Climate Record from the NPP and NPOESS Meteorological Satellites, NationalAcademy Press, Washington, D.C., 2000, pp. 1-6.



1  

See Appendix B for the workshop agenda and a list of participants.

2  

National Research Council (NRC), Space Studies Board. 2000. Issues in the Integration of Research and Operational Satellite Systems for Climate Research: I. Science and Design; National Research Council (NRC), Space Studies Board. 2000. Issues in the Integration of Research and Operational Satellite Systems for Climate Research: II. Implementation, in press.

3  

As defined by the NPOESS IPO, EDRs are data records that contain the environmental parameters or imagery required to be generated as user products as well as any ancillary data required to identify or interpret these parameters or images. EDRs are generally produced by applying an appropriate set of algorithms to raw data records.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

NPOESS data—to be utilized to the maximum extent possible to meet CDR requirements. However, NASA also expects to cap the resources available for CDR processing to ensure that the EDR production requirements are met. Although NPP- and NPOESS-derived EDRs may have considerable scientific value, CDRs are far more than a time series of EDRs. While the lines may be indistinct, there remain fundamental differences between products that are generated to meet short-term needs (EDRs) and those for which consistency of processing over years to decades is an essential requirement. Given the experience of climate researchers, it is unlikely that the standard EDRs will meet the quality requirements for CDRs, particularly in the area of data refinement and reprocessing as algorithms mature. Moreover, production and refinement of CDRs through reprocessing may be difficult (or unaffordable) in the present plans.

Long-Term Archiving and the National Climatic Data Center

NOAA is the federal agency with responsibility for archiving environmental satellite data, and its National Climatic Data Center (NCDC) is a potential repository of data to support climate research in the coming NPP/ NPOESS era. Currently, NCDC has a total digital archive of approximately 700 terabytes (TB). Data from the scheduled launch in 2005 of the NPP satellite will add another 90 TB annually; if managed by NCDC, data from NPOESS in the 2009 time frame would add yet another 228 TB annually.

There are currently no funds to archive NPP or NPOESS data, and although NASA and NOAA have a memorandum of understanding (MOU) regarding the eventual archiving of Earth Observing System (EOS) data by NOAA, it is on a best-effort basis. Although plans are being discussed, there is no implementation strategy within NASA or NOAA to archive even the raw data records (RDRs, analogous to Level 1 data) from these missions. There are also no plans to store sensor design information and calibration and ancillary data necessary to develop CDRs. Ominously, from a climate research perspective, the prospects for developing CDR and long-term archive (LTA) plans for NPP and NPOESS are ever more doubtful, given that plans for the EOS Terra and Aqua (formerly known as AM-1 and PM-1) data sets are not yet firmly in place.

Guiding Principles

NASA and NOAA have experienced both success and failure in recent attempts to develop data systems. The committee believes that much can be learned from these experiences but notes that the fundamental objective of establishing a set of data systems and services to meet the needs of climate research will require more than MOUs and larger magnetic tape silos. New services must be supported that are not available in the present mix of NASA research mission data systems and NOAA long-term archives. New scientific and policy demands are being placed on these systems, and new management and technical approaches must be established. Increasing funding is a necessary condition; however, the committee does not believe that funding alone is sufficient. While encouraged by NASA and NOAA's recent attention to preserving the climate record of NPP, NPOESS, and EOS, the committee believes that an enormous investment in Earth observations is at serious risk.

Based on an examination of prior studies, as well as discussions at its February 7-8, 2000, workshop, the committee identified a set of principles it believes can help ensure the preservation of the climate record from NPP and NPOESS:

  • Accessible and policy-relevant environmental information must be a well-maintained part of our national scientific infrastructure.

  • The federal government should (1) provide long-term data stewardship, (2) certify open, flexible standards, and (3) ensure open access to data. The government does not necessarily need to control the implementation of every task and service for a climate data system. Rather, it should undertake those activities and services that cannot be done in a competitive academic or commercial environment.

  • Because the analysis of long-term data sets must be supported in an environment of changing technical capability and user requirements, any data system should focus on simplicity and endurance.

  • Adaptability and flexibility are essential for any information system if it is to survive in a world of rapidly changing technical capabilities and science requirements.

  • Experience with actual data and actual users can be acquired by starting to build small, end-to-end systems early in the process. EOS data are available now for prototyping new data systems and services for NPP and NPOESS.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×
  • Multiple sources of data and services are needed to support development of climate data records (CDRs). The quality of the CDRs will improve as more research groups work with the various input data sets, and the overall system will be more robust if it does not rely on a monolithic implementation. Fostering open competition for services promotes innovation and new ideas.

  • Science involvement is essential at all stages of development and implementation. Having climate data record developers and users assisting in the specification, design, building, and testing of the system will help ensure its usefulness to the research community.

RECOMMENDATIONS

The committee's study of issues related to the preservation of the climate record from future NASA and NOAA satellites was necessarily brief and drew heavily on previous work and the 2-day workshop. In addition, the committee drew on the lessons learned to date with NASA's EOS Data and Information System. Underlying the committee's recommendations is its belief in the critical need and unique potential for data from NPP and NPOESS to satisfy the demands of the climate research community. In particular, the committee believes that prudent planning and modest investments early in the program will allow the NPOESS system to continue essential climate research-quality data records and develop new records based on the rich blend of planned instruments.

Climate research will require a variety of services, ranging from careful long-term stewardship of the basic data sets to intensive data analysis and algorithm refinement. The committee believes these complex scientific and information system activities are best broken into two more manageable pieces—the long-term archive (LTA) and the active archive—instead of formed into a comprehensive, single-system solution. Climate research requires an integration of the more stable, long-term functionality of the LTA and the flexibility of the active archives to pursue and develop new capabilities.

The first four recommendations of the committee are presented in order of priority. The last four, which are not prioritized, focus on programmatic and management structures to meet these essential requirements for a climate data system.

Recommendation 1. NOAA should begin now to develop and implement the capability to preserve in perpetuity the basic satellite measurements (radiances and brightness temperatures).

The development of long-term, consistent time series based on CDRs requires access to the lowest level of data available. In general, this means the raw data records (RDRs), or Level 1A data. The low-level data can be used to develop refined CDRs as scientific and technical understanding of Earth processes and sensor performance improves over time. The committee recommends that NOAA do the following:

  • Archive both current and future data sets, including those from both research and operational satellite missions, in an LTA.

  • Archive information on sensor development, calibration, operation product validation, and appropriate metadata along with the basic radiances.

  • Migrate data sets to new, computer-compatible media on a regular basis, such that data sets are refreshed every 2 to 3 years consistent with the pace of technology evolution.

  • Organize data in the LTA based on user access patterns to optimize data retrieval.

Recommendation 2. NOAA should guarantee climate researchers affordable access to all RDRs in the long-term archive, with an emphasis on large-volume data access.

Development of CDRs requires access to enormous data volumes, but it is likely that only a small number of researchers will need such extensive access to the raw data. Thus, a well-designed set of basic services would meet this basic function without being too costly. The committee recommends that NOAA act on the following:

  • Award the LTA functions on a competitive basis to both government and private organizations to promote innovation.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×
  • Start the development of the LTA immediately with a simple set of end-to-end capabilities to gain experience and modify the plans and implementation accordingly. (End-to-end is defined as being from sensor aperture to the desktop of the climate information user.)

Recommendation 3. NASA, in cooperation with NOAA, should support the development and evaluation of CDRs, as well as their refinement through data reprocessing.

Because the CDR process is driven by science understanding, there will be a continuing need for the involvement of researchers. The NOAA/NASA Pathfinder shows that the agencies can generate critical data sets for transitioning research products into operational data products. Over the next decades, the committee expects that a few experimental CDRs may become effectively “operational” products and will be produced by NOAA. The committee recommends that NASA, in cooperation with NOAA, take action as follows:

  • Periodically select science investigations and provide adequate support to develop and evaluate new CDRs.

  • Preserve sensor calibration and operating information, as well as metadata and ancillary data fields, in a manner that allows reprocessing the CDRs.

  • Evaluate on a regular basis the organization of data sets in the LTA in light of actual data usage patterns to improve reprocessing and access efficiency.

Recommendation 4. NOAA and NASA should define and develop a basic set of user services and tools to meet specific functions for the science community, with NOAA assuming increasing responsibility for this activity as data migrates to the long-term archive.

NASA's Distributed Active Archives Centers, as well as components of NASA 's Earth Science Information Partners, are gaining experience with responding to data requests and setting up user services. Although the focus is on the order entry process (catalog, data location, browse, etc.), more attention needs to be given to quality assurance and the order fulfillment process (metadata, subsetting, electronic data delivery, etc.). Emphasis should be given to reducing cost through automation. It is essential that the large-volume data sets from the archive be affordable for the science user community. The committee recommends that NOAA and NASA do the following:

  • Select teams on a competitive basis that will identify and provide specific user services and tools (see Appendix D). As part of an ongoing process of system evaluation and improvement, these teams would assist in identifying and providing essential user services. Based on a rigorous analysis of a user model for climate research, they would make recommendations on characteristics such as data subsetting and browse capabilities.

  • Support and maintain a balance between internal and external expertise at the government data centers.

  • Examine the feasibility of providing open electronic access to a rolling archive of RDRs and EDRs through the NESDIS Central that is planned for NPOESS and NPP.

Recommendation 5a. NASA, in cooperation with the Integrated Program Office, should develop the NPOESS Preparatory Project as an integral component of a climate data system.

NPP represents a unique opportunity to test both scientific and programmatic interfaces related to an integrated data systems strategy. It will bridge the gap between the NASA research missions and the NPOESS operational missions. There is potential to begin the development of long-term, high-quality CDRs and an associated data system for climate research, but it is an opportunity that could be missed. The committee recommends that NASA, in cooperation with the NPOESS IPO, proceed as follows:

  • Develop and implement a prototyping activity to link the NPP Science Data Segment with the NOAA LTA. This activity should start with NASA EOS data sets, including Atmospheric Infrared Sounder (AIRS)/Advanced Microwave Sounding Unit (AMSU)/MODIS in anticipation of the NPP data sets, including CriS/ATMS/VIIRS.

  • Put aside reserve funds from data system development to support evolutionary development activities as the program matures to ensure that the system is not locked in with no resources for subsequent enhancement.

  • Develop prototype user services for NPP climate data records.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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Recommendation 5b. Select, on a competitive basis, and then support an NPP science team as soon as possible.

The team should consist of sensor experts, algorithm developers, and science data users. Because the functions will require different levels of involvement in the sensor development and operation process, they will require different levels of support. The team would advise on the NPP data system needs, including scientific data processing, archiving, and distribution requirements.

Recommendation 6. NOAA, in cooperation with NASA, should invest in early, limited capability prototypes for both long-term archiving and the NPP data system.

Data systems that do not develop, test, and evaluate on a frequent, regular basis are nearly always late and over budget. System development costs generally increase as the cube of the number of years in development. A climate data system will build on existing components and existing capabilities, but new functions and new interfaces must be developed and implemented to meet the requirements for climate research. The committee recommends that NOAA, in cooperation with NASA, take action as follows:

  • Competitively select and support a science data team to assist a NOAA long-term archiving program on the following:

    • Archive requirements for long-term data sets, including RDRs, metadata, and ancillary data fields;

    • Archiving of CDRs, algorithms, and processing environments;

    • Data structure and organization to facilitate access and reprocessing;

    • Flexible, open standards to facilitate data access and refinement;

    • Data reprocessing priorities; and

    • Minimal user services and tools.

  • Require the NPOESS total system performance requirements (TSPR) contractor to work with the science data team to facilitate CDR production and archiving from both NPP and NPOESS.

  • Develop flexible standards and formats that allow new services to be developed in the future.

  • Begin to develop a small number of CDRs using the LTA services.

Recommendation 7. NASA and NOAA should develop and support activities that will enable a blend of distributed and centralized data and information services for climate research.

NASA and NOAA should consider a hybrid mode of operation rather than building a rigid, centralized system or relying on structure to emerge from an uncoordinated set of data systems. The government should ensure and manage the activities it does best, while fostering innovation and flexibility in those parts of the overall system that do not need to be closely managed. The committee recommends that NASA and NOAA proceed as follows:

  • Implement the NPP data system as a federation of linked activities, such as that proposed in the NewDISS framework.

  • Where appropriate, build on existing and planned capabilities, including EOSDIS, the Earth Science Information Partners, NASA's Distributed Active Archive Centers, and NOAA's Data Centers, and develop new capabilities as user experience is gained.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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3.8 Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010

A Report of the Committee to Review NASA's ESE Science Plan

Introduction
BACKGROUND

The Earth Science Enterprise (ESE) is one of four science divisions within the National Aeronautics and Space Administration (NASA). Formerly known as Mission to Planet Earth, the ESE deals with space missions and research aimed at observing and understanding the total Earth system and the effects of natural and human-induced changes on the global environment.1 Approximately 20% of the $1.4 billion ESE budget for FY00 is devoted to research and analysis and 70% is spent on mission development and operations.2 The current centerpiece of the ESE is the Earth Observing System (EOS), a series of large, multi-instrument orbital platforms that will measure 24 parameters needed to understand global climate change. Other important ESE missions and studies focus on understanding the dynamics of the solid Earth and natural hazards such as earthquakes and volcanic eruptions, as well as other ocean, atmosphere, and land phenomena.

As originally conceived, the EOS program was intended to include three series of platforms collecting 15 years' worth of data, but in response to congressional direction, external reviews,3,4 and a recognition of the need for greater flexibility, NASA has restructured the program. Current plans call for deployment of a suite of smaller spacecraft (systematic observation missions, exploratory missions, and technology demonstration missions) from 2003 to 2010, each carrying a limited number of research instruments, to follow the first series of EOS platforms. The National Research Council (NRC) reviewed the revised mission plans in 1999,5 and among that assessment's major recommendations was a call for NASA to develop a “fully integrated science plan.” In its formulation of the administration's FY01 budget proposal, the Office of Management and Budget directed NASA to develop such a plan and to have it reviewed by the NRC before decisions would be made about the content of the Earth science program.

CHARGE AND APPROACH

In response to a request from NASA (Appendix A), the Committee to Review NASA's Earth Science Enterprise Science Plan was assembled to review NASA Earth Science Enterprise Research Strategy for 2000-2010, the overview of NASA ESE Science Implementation Plan. The committee was asked to assess the following: (1) the characterization of the issues and primary questions the Plan proposes to address; (2) the criteria and prioritization process described for both the science questions and the definition of mission concepts; and (3) the soundness of the selection of detailed questions to be pursued, particularly in light of existing NRC reports, such as Global Environmental Change: Research Pathways for the Next Decade. 6

The committee's report begins with a summary of findings and recommendations. Sections III through V address, respectively, the primary science issues, the detailed science questions, and NASA's responsibility for answering the detailed questions. The detailed science questions are listed in Appendix B. Section VI discusses the criteria for setting research priorities and for choosing future missions. Appendix C indicates how the criteria

  

NOTE: "Introduction" reprinted from Review of NASA's Earth Science Enterprise Research Strategy for 2000-2010, National Academy Press, Washington, D.C., pp. 1-3.

1  

NASA, 2000, Exploring Our Home Planet: The Earth Science Enterprise Strategic Plan. May 25, 2000, draft.

2  

Details of the FY 2000 budget are given online at < http://ifmp.nasa.gov/codeb/budget.2001/ >.

3  

NRC, 1995, A Review of the U.S. Global Change Research Program and NASA's Mission to Planet Earth. National Academy Press, Washington, D.C., 96 pp.

4  

Independent External Review Panel (NASA), 1997, “Assessment of 1997 MTPE Biennial Review.” Letter to Daniel Goldin, 6 pp.

5  

NRC, 1999, “On NASA's Plans for Post-2002 Earth Observing Missions.” Letter report to Ghassem Asrar, NASA's Associate Administrator for Earth Science, 45 pp.

6  

NRC, 1998, Global Environmental Change: Research Pathways for the Next Decade. National Academy Press, Washington, D.C., 595 pp.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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TABLE 1. Comparison of ESE Program Structure with USGCRP Program Elements

ESE Research Themes (Program Structure)

USGCRP Program Elementsa

Oceans and ice in the Earth system

Understanding the Earth's climate system

Biology and biogeochemistry of ecosystems and the global carbon cycle

Biology and biogeochemistry of ecosystems

Carbon cycle science

Atmospheric chemistry, aerosols, and solar radiation

Composition and chemistry of the atmosphere

Global water and energy cycle

The global water cycle

Solid Earth science

Paleoclimate/paleoenvironment

 

Human dimensions of global change

aSubcommittee on Global Change Research, 1999, Our Changing Planet: The FY2000 U.S. Global Change Research Program Implementation Plan and Budget Overview. Washington, D.C., 100 pp.

discussed in Section VI would be applied in an Announcement of Opportunity for exploratory missions. Section VII discusses strategic elements of a research strategy and provides specific suggestions for improving the Plan. Finally, the committee's conclusions are summarized in Section VIII.

THE ESE RESEARCH STRATEGY

The NASA Earth Science Enterprise Research Strategy for 2000-2010 was written explicitly to delineate the science objectives and questions that NASA can address and a strategy for addressing those questions. Although the document is called a research strategy, it contains elements of both a strategy, in that it identifies the science questions to be answered, and an implementation plan, in that it shows, for example, how the questions are to be answered by measuring specific quantities. In the review that follows, the document is referred to simply as the Plan.

NASA's Earth Science Enterprise addresses research problems related to Earth's natural systems. Its research strategy is organized around five primary Earth system science issues. Each of the primary science issues is followed by a list of detailed science questions and the criteria according to which the questions were ranked. The quantities needed to answer the detailed science questions are summarized in tables, one for each primary science issue. A discussion of ESE research themes (i.e., ESE's program structure) closes the document.

RELATIONSHIP OF THE ESE TO THE U.S. GLOBAL CHANGE RESEARCH PROGRAM

The ESE research program is divided into five disciplinary themes, including oceans and ice, ecosystems, atmospheric chemistry, global water and energy cycle, and solid-Earth science. This mix of disciplines reflects NASA's heritage as a provider of space-based observing systems for addressing a wide range of research problems in the natural sciences. Many of these problems are also relevant to global change research, and NASA has designated certain components of the ESE as its contribution to the U.S. Global Change Research Program (USGCRP).7 The global change component of the ESE is the largest agency contribution to the program, accounting for 70% of the total USGCRP budget and 100% of the USGCRP's space-based observation programs. The ESE program structure has significant overlaps with, but also key differences from, the USGCRP program structure (see Table 1). For example, the ESE disciplinary themes include solid-Earth science (including geodesy and natural hazards), but not social science. The other four disciplinary themes of the ESE address most of the program elements of the USGCRP.

7  

The USGCRP was established in 1989 to develop and coordinate a research program to understand, assess, predict, and respond to natural and human-induced global change. Nine federal agencies and the Executive Offices of the President participate in the program. See Subcommittee on Global Change Research, 1999, Our Changing Planet: The FY2000 U.S. Global Change Research Program Implementation Plan and Budget Overview. Washington, D.C., 100 pp.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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3.9 Federal Funding of Astronomical Research

A Report of the Committee on Astronomy and Astrophysics

Executive Summary

As the result of a study to address questions about trends in and the current state of federal funding for the field of astronomy, the Committee on Astronomy and Astrophysics (CAA) developed the following four principal findings in response to the charge outlined in the Preface:

Finding 1. There has been a dramatic shift in the source of the funding for individual research grants in astronomy, with the National Science Foundation's (NSF's) share falling from 60 percent at the beginning of the 1980s to 30 percent at the end of the 1990s. The National Aeronautics and Space Administration's (NASA's) share of the grant funding has risen commensurately.

The continuing growth in funding for astronomy in the 1980s and 1990s has been largely the result of the success of NASA's space science program, in particular the launch of NASA's Great Observatories and several midsized facility-class satellites. Another important factor in the growth in funding for astronomy has been a large influx of private funding (from foundations and universities) for the construction of ground-based telescopes.

Finding 2. The overall level of federal support for astronomy remains strong, but shifts in funding patterns, with NSF supplying a declining percentage of grant funding relative to NASA, have the potential to create imbalances that could be detrimental to the overall health of the field. For example, funding for broad-based astrophysical theory has not kept pace with the growth in funding for astronomical research overall.

With NSF's relative role in astronomy continuing to shrink, the subfields that depend primarily on NSF funding are vulnerable. Over the past 15 years, there has been essentially no significant change in the annual budget of NSF's Division of Astronomical Sciences. As a consequence, the fraction of support for the U.S. astronomy enterprise provided by NSF has declined. This trend substantially affects the grants programs, since the number of astronomers has increased over the same 15-year period by more than 40 percent. Increases in NASA funding have taken up the shortfall in some areas such as optical and infrared astronomy; however, an increasing emphasis on mission-oriented support has created vulnerabilities in those subfields for which NASA support is not readily available, such as broad-based theory, computational astrophysics, and radio astronomy, where some erosion in grant funding already is evident. The committee was unable to produce an exhaustive list of vulnerable research areas but suggests that funding balance across subfields of astronomy is an important issue that requires further study.

Finding 3. Although the number, size, and capability of ground-based observing facilities, both public and private, have increased considerably, there has been no commensurate increase in NSF funds for utilizing these facilities (i.e., for instrumentation, individual research grants, or theory).

Rapid growth and change create problems of adjustment. Funding for utilization of both ground- and spacebased astronomical facilities remains an important issue. There are some fields of astronomy in which support has not been adequate to exploit the dramatic scientific discoveries of the last decade or to pursue the opportunities offered by the explosion in scientific capabilities. For instance, ground-based facilities have grown in number and scope with the completed, or soon to be built, large, private- and state-funded ground-based telescopes and with NSF initiatives that include the Green Bank Telescope, the Gemini telescopes, the Arecibo telescope upgrade, and the Atacama Large Millimeter Array (ALMA/MMA). Yet funding for instrumentation, theory, and observer grants at NSF has not kept pace with support for construction. Facility instrumentation for major new telescopes is a clear

NOTE: "Executive Summary" reprinted from Federal Funding of Astronomical Research, National Academy Press, Washington, D.C., 2000, pp. 1-3.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

need for the foreseeable future in response to the leaps in technical capabilities and the large increase in telescope collecting area. Training of instrumentalists for both ground- and space-based facilities is also an outstanding need.

Finding 4. As a result of NASA's increased role in astronomical research funding, a large portion of the total support is tied to a few flagship space missions.

NASA is a mission agency whose program is strongly focused on initiating and launching space-based instruments. Funding for operations and research accompanies each mission. This paradigm has been extremely effective in maximizing the scientific return from these missions. However, the worrisome corollary of this arrangement is the potential for premature termination of the research support associated with a mission in the event of a catastrophic mission failure. Although NASA has a strategic planning process that is quite effective in engineering smooth transitions from one mission to another, there appears to be little explicit planning for unexpected or premature mission termination.

If a centerpiece astronomical research mission in space were to fail at a time when follow-on missions were far in the future, the impacts would include not only the loss of a major observational tool, but also the premature termination of the stream of research data and the flow of funds to analyze the data. Because analyzing the data from such major missions is the work of a significant fraction of the astronomy and astrophysics research community, the personnel impact could be substantial, which could in turn dampen the community 's ability to help plan for, and utilize, future missions. For example, the Hubble Space Telescope (HST) grants program accounts for roughly 25 percent of all individual investigator funding in astronomy. It supports researchers at all levels, including students and postdoctoral fellows. In the event of an HST failure, the additional loss of jobs directly associated with the Space Telescope Science Institute and NASA's Goddard Space Flight Center would be substantial, not to mention the loss of a primary scientific capability. Recovery of the scientific personnel complement and the nation's astronomical research capability from such a catastrophe would be slow.

Most important is that a significant fraction of the support for the youngest members of the field comes from such missions. The impact on the youngest astronomers, such as those supported by Compton Gamma Ray Observatory, Hubble, and Chandra fellowships and those supported by the research and analysis (R&A) funds for such missions, would be disproportionately large and would significantly affect the future of the field.

The committee's four findings have led it to suggest that the following proposition be considered in future assessments of the field: plans for future facility construction, both ground and space based, should be accompanied by a strategy to accomplish the scientific mission, including provision of instrumentation for ground-based telescopes, support for observations, and funds for the necessary and relevant astrophysical theory. The strategy should address the following objectives:

  • Ensuring continuity of research in critical subfields in the event that major facilities are lost or significantly delayed;

  • Developing new instrumentation for both space- and ground-based facilities;

  • Training instrumentalists;

  • Optimizing the distribution of spending on hardware and personnel; and

  • Maintaining flexibility to respond to changes in the directions of research in astronomy and astrophysics.

In conclusion, the committee found the field of astronomy in the United States to be in generally good health. The United States still leads the field. New discoveries continue to be made at a quickening pace. Observational capability continues to grow rapidly with the construction and deployment of ground- and space-based instruments of remarkable power. There is strong public interest in astronomy. However, the dramatic shift in the majority of research grant support from NSF to NASA over the past two decades has led to a system in which the funding for subfields that cannot rely on NASA support has eroded somewhat and the funding for the field as a whole is vulnerable to the unexpected termination of a major NASA mission.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

3.10 Review of NASA's Biomedical Research Program

A Report of the Committee on Space Biology and Medicine

Executive Summary

The 1998 Committee on Space Biology and Medicine (CSBM) report A Strategy for Research in Space Biology and Medicine in the New Century (NRC, 1998) assessed the known and potential effects of spaceflight on biological systems in general and on human physiology, behavior, and performance in particular, and recommended directions for research sponsored over the next decade by the National Aeronautics and Space Administration (NASA). The present follow-up report reviews specifically the overall content of the biomedical research programs supported by NASA in order to assess the extent to which current programs are consistent with recommendations of the Strategy report for biomedical research activities. In general, NASA programs concerned with fundamental gravitational biology are not considered here. The committee also notes that this report does not include an evaluation of NASA's response to the Strategy report, which had only recently been released at the initiation of this study.

Summarized below are the committee's findings from its review of (1) NASA's biomedical research and (2) programmatic issues described in the Strategy report that are relevant to NASA's ability to implement research recommendations.

NASA BIOMEDICAL RESEARCH

Most of the biomedical research funded by NASA is carried out through (1) a program of NASA Research Announcements that funds proposals by individual investigators, (2) research conducted in scientific or clinical programs at either the Johnson Space Center (JSC) or the Ames Research Center (ARC), and (3) focused research projects managed by the National Space Biomedical Research Institute (NSBRI). The committee considered all NASA biomedical research projects, irrespective of their origin, under the following disciplinary categories:

  • Sensorimotor integration,

  • Bone physiology,

  • Muscle physiology,

  • Cardiovascular and pulmonary systems,

  • Endocrinology and nutrition,

  • Immunology and microbiology,

  • Radiation biology, and

  • Behavior and performance.

In order to assess the degree to which NASA's research programs will meet the agency's needs for biomedical knowledge in the next 10 years, the committee compared current and planned research to the recommendations made in the Strategy report. Within this context, the committee attempted to answer the following questions.

What Is the Balance of Discipline Areas in NASA's Biomedical Research Program?

The Strategy report gave the highest overall priority to specific research questions dealing with bone and muscle loss, changes in the function of the vestibular and sensorimotor systems, orthostatic intolerance, radiation hazards, and the physiological and psychological effects of stress. Although the committee found the balance of NASA research between the various biomedical disciplines to be generally consistent with the relative emphasis given to them in the Strategy report, many of the specific research topics given the highest overall priority are still to be addressed. Noted below is the degree to which these research topics appear in the current program. It should be

NOTE: "Executive Summary" reprinted from Review of NASA's Biomedical Research Program, National Academy Press,Washington, D.C., 2000, pp.1-6.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

kept in mind that many of the Strategy report recommendations called for specific microgravity investigations that cannot be carried out until appropriate flight opportunities again become available.

As recommended, mechanistic studies and the use of ground-based animal models to understand changes in bone and muscle during and after spaceflight are being emphasized in NASA's current program. Preliminary ground studies of the relationship between exercise activity and protein-energy balance have also been started. Implementation of recommendations to collect in-flight astronaut data on bone loss and hormonal profiles must await flight opportunities.

Some preliminary investigations have been carried out that are relevant to the recommendation for in-flight recordings of signal processing following otolith afferent stimulation. However, the recommendation to study the basis for compensatory vestibulomotor mechanisms on Earth and in space has not yet been addressed. The performance of the recommended microgravity studies on neural space maps and pattern learning in the vestibulooculomotor system will depend on the availability of flight opportunities.

Mechanistic studies of total peripheral resistance responses during postflight orthostatic stress have been conducted on the recent Neurolab mission and in the cardiovascular laboratory at JSC. The Mir cardiovascular experiments were relevant to the recommendation to examine cardiovascular changes on long-duration missions. However, inadequate plans exist to monitor these changes on the International Space Station. Current pulmonary studies focus on the issue of decompression sickness but do not address aerosol deposition and respiratory muscle function.

Studies to examine the space radiation-induced risks of cancer and central nervous system damage are being carried out by NSBRI investigators at new facilities at Loma Linda University for proton studies and at Brookhaven for heavy ions. These will provide greatly improved access to investigators for relevant studies. Flights are not yet available for the recommended study of the combined effects of radiation and stress on the immune system, and no preliminary ground studies on this issue appear to be planned.

The majority of NASA-supported psychosocial research is currently directed toward the recommended studies of neurobiological mechanisms involved in circadian rhythm and sleep disturbances, and there are strong indications that NASA also plans to give explicit emphasis to the recommended studies on psychosocial mechanisms in the future. However, the work recommended on countermeasure evaluation and development has so far received little attention, with the exception of circadian and neurovestibular system studies.

What Is the Balance Between Ground and Flight Investigations?

The majority of NASA's current and planned biomedical studies are ground based due to the limitation in flight opportunities over the next several years. Some notable exceptions include behavioral research and sensorimotor integration, which have a significant percentage of experiments in the flight program. As for radiation biology, its program focus on ground-based research is consistent with the recommendations of the Strategy report. However, the Strategy report recommended a major flight component for most discipline research programs, and the current lack of appropriate flight opportunities may lead to delays in the development of needed countermeasures for physiological changes such as orthostatic intolerance and muscle loss. Although it is possible, and even necessary, to perform much of the preliminary work on the ground, many of the critical research questions cannot be resolved without in-flight studies.

To What Degree Are Studies of Fundamental Cellular and Physiological Mechanisms Addressed in Research Programs?

In general, there is a strong and very appropriate degree of emphasis on mechanistic studies across the various biomedical disciplines, as recommended in the Strategy report. In the area of bone physiology, for example, an independent program of basic cellular and molecular biology has been initiated at ARC, while an NSBRI laboratory is taking pharmacologic approaches to the study of biochemical pathways. Some of the specific mechanistic studies recommended in the Strategy report remain to be addressed, however, with studies of psychosocial mechanisms being particularly sparse.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×
What Are the Plans for Validation of Animal Models?

In most of the disciplines for which a need for animal research was cited in the Strategy report, NASA is making significant use of animal models. However, their use in sensorimotor integration studies is thus far limited to only a few of the recommended research topics. One widely utilized animal model is hindlimb unloading in rodents, which is being used to study muscle atrophy, bone loss, and immunological changes.

The extent to which the various animal models are being tested to confirm that they duplicate certain physiological changes seen in space-bound humans was more difficult for the committee to determine. However, it is known that attempts have been made, or are planned, to validate aspects of the models used in bone and immunology studies. It was noted that evaluation is needed of the models used in studies of cardiovascular adaptation and endocrine changes.

What Are the Plans for the Development and Validation of Physiological and Psychological Countermeasures?

Although NASA has countermeasures in place for a number of the adverse effects of spaceflight on humans, many have not been rigorously tested for efficacy and side effects. However, the development of future counter-measures is the primary focus of NSBRI research, and JSC is developing an administrative mechanism for soliciting and testing countermeasures. Issues related to implementing this process are discussed under programmatic issues below.

Most of NASA's discipline programs include some level of research activity directed at adverse effects, such as bone and muscle loss, for which no effective countermeasure exists. Studies include investigation of the respective effects of pharmacologic intervention, nutrition, and centrifugation on bone loss, renal stone formation, and sensorimotor impairment. However, there is considerable variation in the organization and scope of these activities. Although studies on respiratory tract infections appear likely to meet countermeasure goals, planning appears to be very limited for developing and testing countermeasures for orthostatic intolerance, psychosocial deficits, and radiation effects.

What Are the Plans to Perform Epidemiology and Monitoring?

Plans exist to monitor indicators for a number of physiological changes in International Space Station (ISS) astronauts. These include measurements of bone density change, radiation exposure, orthostatic intolerance, and cardiac atrophy after missions longer than 30 days. Muscle atrophy will be monitored as part of a program of countermeasure testing, and the capability for in-flight monitoring of psychological status is planned. There are, however, a number of factors that may limit the usefulness of the collected data. Much of the data is collected for medical operations purposes and will not be accessible to the scientific community, nor in many cases do there appear to be plans even within the clinical program to systematically analyze and interpret the data. In addition, it is not clear that in every discipline the techniques best suited to the measurement, such as the use of magnetic resonance imaging (MRI) to measure cardiac mass, will be used on a routine basis.

To What Extent Are Programs Supporting New, Advanced Technologies and Methodologies?

Considerable attention is being paid to the development of new technologies and methodologies that can be used in basic research, monitoring of in-flight physiological changes, and countermeasures. This seems to be true across nearly all discipline programs and in all components of the program. It is a particular focus of work at NSBRI. Some of the more innovative approaches under development include a portable bone densitometer, virtual environments to study human perception and navigation, and advanced telemetric-based sensor systems.

PROGRAMMATIC ISSUES

The 1998 Strategy report raised a number of concerns in the program and policy arena, including issues relating to strategic planning, conduct of space-based research, and utilization of the ISS; mechanisms for promoting integrated and interdisciplinary research; and collection of and access to human flight data. The committee looked

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

at both the current program and what was known regarding future plans in order to evaluate the congruence with Strategy report recommendations. Additional overarching issues having to do with countermeasure testing and validation and with the role of the office of Medical Operations in human research, came to the committee 's attention during the course of the present study. Some of the most significant issues that remain to be addressed follow.

International Space Station: Utilization and Facilities

The adequacy of the life sciences research facilities that will actually be in place on the ISS at its final build-out remains an issue of serious concern. Possible design changes, the mounting delays in utilization timetables, and the perceived potential for downgrading of research facilities and budgets have continued to erode the confidence of the user scientific community. Important questions also remain about the availability of Russian cosmonauts for long-term follow-up in the conduct of biomedical research, especially in the early phases of ISS utilization.

Countermeasure Testing and Validation

The need for effective countermeasures against the deleterious effects of spaceflight on astronaut health and performance will become increasingly critical as longer-duration flights become the norm on the ISS and beyond. The development of effective, mechanism-based countermeasures requires three well-integrated phases: (1) basic research to identify and understand mechanisms of spaceflight effects; (2) testing and evaluation of proposed countermeasures to determine their efficacy; and (3) validation of promising countermeasures by well-designed clinical studies. Recently, NASA has begun to develop a standard procedure for testing and evaluating counter-measures, but this has not yet been implemented. It is essential that the process, once in place, be readily accessible to all investigators, extramural as well as intramural, and that criteria for acceptance into the testing program be clearly defined.

Operational and Research Use of Biomedical Data

Access to in-flight biomedical data, as well as to longitudinal data collected during postflight longitudinal monitoring of astronaut health, is limited, and the partial and incomplete availability of human data to qualified investigators was highlighted as a major concern in the Strategy report and continues to be an issue. The committee urges that NASA explore ways in which these data and samples, collected in the past and future, can be made available to investigators. Additionally, steps are needed to ensure that future data collection includes measurements and sampling that have been optimized to give the most useful information on in-flight development of problems and postflight recovery of normal physiological function. The role played by the crew surgeon is especially critical to collection of these data, and rigorous training in clinical research and basic research is recommended as a requirement for the position.

POLICY ISSUES
International Cooperation

The era of ISS construction and utilization, with increased emphasis on international crews and operations, raises important issues with respect to acquisition and management of human data. Mechanisms are needed to ensure that protocols and facilities for pre- and postflight monitoring and testing are consistent across national boundaries. There must be common criteria for evaluation and utilization of countermeasures and international cooperation in their development.

Integration of Research Activities

NASA funding for biomedical research is increasingly distributed among a diverse set of organizations and programs. These include the program of NASA Research Announcements (NRAs), intramural investigators in NASA center science programs, the NSBRI, and the NASA Specialized Centers of Research and Training. NASA

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

science benefits from the unique strengths of each of these program constituents, but careful planning is required to delineate the roles, responsibilities, and appropriate funding levels for each; to ensure effective collaborations; and to integrate research findings. In particular, NASA should maintain a healthy NRA program as the primary mode for support of space-related biomedical research because it remains the best method of accessing the entire investigator community and exploring novel ideas and approaches.

REFERENCE

National Research Council (NRC), Space Studies Board. 1998. A Strategy for Research in Space Biology and Medicine in the New Century. Washington, D.C.: National Academy Press.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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3.11 Issues in the Integration of Research and Operational Satellite Systems for Climate Research: I. Science and Design

A Report of the Committee on Earth Studies

Executive Summary
INTRODUCTION

Currently, the Departments of Defense (DOD) and Commerce (DOC) acquire and operate separate polar-orbiting environmental satellite systems that collect data needed for military and civil weather forecasting. The National Performance Review (NPR)1 and subsequent Presidential Decision Directive (PDD)/NSTC-2, dated May 5, 1994, directed the DOD (Air Force) and the DOC (National Oceanic and Atmospheric Administration, NOAA) to establish a converged national weather satellite program that would meet U.S. civil and national security requirements and fulfill international obligations.2 NASA's Earth Observing System (EOS), and potentially other NASA programs, were included in the converged program to provide new remote sensing and spacecraft technologies that could improve the operational capabilities of the converged system. The program that followed, called the National Polar-orbiting Operational Environmental Satellite System (NPOESS), combined the follow-on to the DOD's Defense Meteorological Satellite Program and the DOC's Polar-orbiting Operational Environmental Satellite (POES) program. The tri-agency Integrated Program Office (IPO) for NPOESS was subsequently established to manage the acquisition and operations of the converged satellite.

NASA officials have long envisioned developing operational versions of some of the advanced climate and weather monitoring instruments planned for EOS. In its 1995 EOS “Reshape” exercise, NASA adopted the assumption that some of the planned measurements in the second afternoon (PM) satellite series would be supplied by NPOESS. Although NASA has altered its earlier plans for the PM satellite and other follow-on missions to the first EOS series, its intent to integrate NPOESS into its Earth observation missions remains intact.

This report, the result of the first phase of a study by the Committee on Earth Studies, analyzes issues related to the integration of EOS and NPOESS, especially as they affect research and monitoring activities related to Earth's climate and whether it is changing.3 The development of high-quality, long-term satellite-based time series suitable for detection of climate change as well as for characterization of climate-related processes poses numerous challenges. In particular, achieving NASA research aims on an NPOESS satellite designed to meet the high-priority operational needs of the civil and defense communities will require agreement on program requirements, as well as coordination of instrument development activities, launch schedules, and precursor flight activities.

The study of climate processes requires a coherent, comprehensive system that carefully balances research requirements that are sometimes in conflict with operational requirements. Long-term, consistent data sets require careful calibration, reprocessing, and analysis that may not be necessary to meet the needs of short-term forecasting. Acquisition of multiple copies of a satellite sensor may be the simplest and most cost-effective means to ensure data continuity, but this strategy may preclude the insertion of new techniques to improve the observations in response to lessons learned during analysis of long data records. Such conflicts are difficult to resolve and are complicated by differences in agency cultures, charters, and financial resources.

NOTE: "Executive Summary" reprinted from Issues in the Integration of Research and Operational Satellite Systems for Climate Research:I. Science and Design, National Academy Press, Washington, D.C., 2000, pp. 1-6.

1  

See DOC12: “Establish a Single Civilian Operational Environmental Polar Satellite Program,” in Appendix A of From Red Tape to Results: Creating a Government that Works Better and Costs Less (National Performance Review Part I). Available on the World Wide Web at < http://www.npr.gov/library/nprrpt/annrpt/redtpe93/index.html >.

2  

“Fact Sheet: U.S. Polar-Orbiting Operational Environmental Satellite Systems and Convergence of U.S. Polar-Orbiting Operational Environmental Satellite Systems and Landsat Remote Sensing Strategy,” statement by the White House Press Secretary, May 10, 1994. Available on the World Wide Web at < http://www.whitehouse.gov/WH/EOP/OSTP/NSTC/html/pdd2.html >.

3  

The committee's forthcoming phase two report, Issues in the Integration of Research and Operational Satellite Systems for Climate Research: II. Implementation (NRC, 2000), addresses systems engineering issues related to sensor replenishment and technology insertion, explores technical approaches to data continuity and interoperability from the standpoint of data stability, and considers issues in instrument calibration and data product validation.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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APPROACH AND OBSERVATIONS

In performing its assessment, the committee reviewed eight variables (eight measurement areas) that it believed to be representative of the wide-ranging set of potential variables to be measured in a climate research and monitoring program. The committee adopted this strategy in part because there is no unique set of “climate variables,” nor is there consensus on what might constitute a minimal set of variables to be monitored in a climate research program. The committee assessed the eight variables in terms of their value to climate science and whether the present state of measurements and their associated algorithms were adequate to produce “climate-quality” data products. Included in the committee's analysis is an assessment of the role of new technology or new measurement strategies in enhancing existing climate data products or delivering new data products of interest.

Common Issues

In its review of the eight representative climate variables the committee identified the following common issues:

  • Need for a comprehensive long-term strategy. Systems for observing climate-related processes must be part of a comprehensive, wide-ranging, long-term strategy. Monitoring over long time periods is essential to detecting trends such as changes in sea-surface temperature and to understanding critical processes characterized by low-frequency variability. The committee notes that an observing system developed for long-term climate observations may also very well reveal unexpected phenomena, as was the case with observations of the large-scale, low-frequency El Niño/Southern Oscillation.

  • Desirability of multiple measurements of the same variable using different techniques. Corroborating results from a variety of observing techniques increases confidence in the data; conflicting measurements suggest problems in data quality or newly emerging science questions that must be resolved.

  • Diversity of satellite observations and sampling strategies and support for ground-based networks. While plans for NPOESS and EOS have focused primarily on polar-orbiting satellites, satellite observations from other orbits (low inclination, geostationary) have important roles in the development of a climate observing system. Differing sampling strategies will also be needed to tailor measurement requirements to instrument capabilities in a cost-effective manner.

Ground-based networks support and extend the space-based observations. They are critical for calibrating and validating space-based measurements; they also complement space-based measurements and often provide the high-resolution measurements in both time and space needed to carry out the process studies that elucidate the mechanisms underlying climate-related phenomena. In reviewing its notional set of eight climate variables, the committee found that more attention to development of ground-based networks was warranted.

  • Preserving the quality of data acquired in a series of measurements. A particular challenge in the design of a climate observing system is how to preserve data quality and facilitate valid comparisons of observations that extend over a series of spacecraft. With the regular insertion of new technology driven by interest in reducing costs and/or improving performance also comes the need to separate the effects of changes in the Earth system from effects ascribable to changes and gaps in the observing system. Effective, ongoing programs of sensor calibration and validation, sensor characterization, data continuity, and strategies for ensuring overlap across successive sensors are thus essential. Data systems should be designed to meet the need for periodic reprocessing of the entire data set.

  • The role of data analysis and reprocessing. An active, continuous program of data analysis and reprocessing adds value to existing data sets and enables the development of new algorithms and new data products.

  • Technology development and improved measurement capabilities. New sensors are needed to reduce costs and to improve existing measurement capabilities. In addition, some climate-related variables, for example, soil moisture, cannot be measured adequately with existing capabilities. Moreover, it is not clear that all critical climate-related variables have even been identified. With improved coordination with NOAA and the IPO for NPOESS, NASA technology development efforts would better address these issues and help provide increased capabilities for the operational meteorological system.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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Carrying Out Climate Research from Space-Based Platforms

Operational agencies generally respond to short-term demands for data products; research agencies are also under increasing pressure to respond to short-term demands for technology development and science missions that can be accomplished in a few years. As a result, political and programmatic pressures for short-term returns (both in terms of science and protection of life and property) have resulted in an operational agency focus on the acute problems of storms, earthquakes, and other severe events—even though there is growing evidence that the long-term trends associated with climate will have significant economic and social impacts. Addressing the issues associated with climate will require a long-term focus and a commitment to maintain long-term, high-quality observing systems.

Climate research and monitoring require a blend of short-term, focused measurements as well as systematic, long-term measurements. While the generally shorter-term and more detailed studies that characterize process studies might appear to be in opposition to a long-term program of systematic measurements, the committee emphasizes that climate-related processes are often revealed only through the study of data from long-term systematic measurements. Achieving an appropriate balance across agencies between short-term and long-term activities related to climate research, such as a balance between process studies and monitoring activities, has proved difficult. Recent NRC studies have recommended that the Executive Branch establish an office to develop and manage a climate observing strategy.4

NPOESS and Climate Research

The 1994 Presidential Directive to converge DOD and DOC meteorological programs initiated a lengthy process among Air Force and NOAA operational and research users to produce a detailed list of measurement requirements. The culmination of this effort was the Integrated Operational Requirements Document (IORD-1) that was formally endorsed by NOAA, DOD, and NASA.5 The IORD-1 consists of 61 environmental data records (EDRs) deemed necessary to the success of NPOESS. The EDRs are distributed among six categories: atmospheric parameters, cloud parameters, Earth radiation budget parameters, land parameters, ocean and water parameters, and space environmental parameters.

The EDRs developed in the IORD-1 describe a well-defined, detailed set of measurements that have demonstrable value in the primary NPOESS mission of short-term weather forecasting. Climate research and modeling, however, require assimilation and analysis of a much broader set of measurements that may also be characterized by different time and space scales. Instrument stability is a key consideration in the analysis of whether climate variables are changing, yet it is undefined for many of the EDRs. Further, the IORD-1 does not set requirements on the stability or longevity of the stipulated measurements.

Despite these problems, the committee believes that NPOESS offers a unique opportunity to establish a satellite-based observing system for climate research and monitoring. Although the NPOESS and NASA EOS missions as currently planned may not be optimum for climate research, many of the critical components are already in place. These include an initial commitment to data stability on the part of the NPOESS IPO, an active program of data analysis and data product validation by NASA's Earth Science Enterprise (ESE), and an active plan for NASA and NOAA collaborative missions such as the NPOESS Preparatory Project. The committee is concerned, however, that budget pressures, shifting programmatic interests, and a lack of overall vision and leadership may continue to inhibit the establishment of a coherent Earth observing system for climate research and monitoring.6

Challenges in the Integration of NASA/ESE and NOAA/NPOESS Programs
  • Division of responsibility in the integration of research and operational missions. Climate research and monitoring raise issues that transcend the capabilities of any single federal agency. Yet, in the committee 's view, no

    4  

    See, for example, NRC (1998, 1999b).

    5  

    An updated IORD and other documentation related to the NPOESS program are available online at < http://npoesslib.ipo.noaa.gov/ElectLib.htm >.

    6  

    An additional set of issues relates to the development of suitable long-term climate data archive, the subject of another study by the committee, Ensuring the Climate Record from the NPP and NPOESS Meteorological Satellites, currently in press.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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effective structure is currently in place in the federal government that can address such multiagency issues as the balance between satellite-and ground-based observations, long-term and exploratory missions, and research and operational needs. The committee concurs with recent NRC reports that have expressed concern over the lack of overall authority and accountability, the division of responsibility, and the lack of progress in achieving a long-term climate observing system. 7 The challenges in integrating ESE research satellite missions and NPOESS operational satellite missions underscore these critical issues.

  • Adequacy of NPOESS environmental data requirements for climate research. The EDR process established by the IPO supports the primary operational goals of DOD and NOAA but was not intended to yield instrument specifications that meet climate research requirements. For example, many climate research studies require access to unprocessed sensor-level data, whereas the EDR approach focuses on the final data products. In many cases, the current EDRs are not completely specified, and in some, they are not adequate for climate research. A particular issue is the absence of measurement stability and longevity specifications for many of the EDRs.

  • Ensuring the long-term (systematic) record begun by EOS. NASA's ESE plans that certain measurements begun on EOS satellites will be integrated later into the NPOESS program. However, given the budgetary and programmatic uncertainties that have historically characterized the EOS program, there can be no assurance that this integration will be successful. Further, the committee notes that while long-term observations are essential for climate studies, NASA's new EOS plan focuses on short-term (3 to 5 years) missions. For NASA to be able to pursue a science-based strategy that leverages NPOESS capabilities where possible, the agency will probably also have to fly complementary missions and collect specialized data sets.

Satellite observing systems are developed for a range of objectives that sometimes conflict, leading to the need for a framework to evaluate trade-offs and to manage risk. The NPOESS Preparatory Project (NPP) under consideration by NASA and the IPO is an encouraging step toward addressing the need to maintain continuity of critical data sets between the end of the EOS platforms and the launch of the first NPOESS platforms.

  • Development of sustainable instrumentation. Sensors developed for NASA ESE research missions are generally intended to make ambitious state-of-the-art measurements. They are typically relatively complex and often are developed in small numbers, or even as one of a kind. In contrast, sensors for operational weather forecasting missions are generally less expensive to build and operate and are designed with reliability as a key requirement. Repeat flights of identical sensors are typical in NOAA operational meteorology programs. Developing instruments appropriate for both research- and operational-type missions that can be sustained over the longer periods characteristic of a climate research program will be a particular challenge as EOS and NPOESS satellites are integrated.

  • Prioritizing and establishing an observing strategy. The climate research community has not yet prioritized critical data sets or developed an overall national observing strategy, including algorithm development, calibration and validation, ground observations, and new technology. Climate research priorities should reflect scientific need, while recognizing technological, fiscal, and programmatic constraints. Other important aspects of such a strategy will be periodic evaluation and readjustment of specific mechanisms for transferring data sets from research to operations. Articulation of a long-term context, spanning as much as a century or more, will be paramount in developing a credible climate observing policy.

RECOMMENDATIONS

The following recommendations are directed to the climate research community, NASA's Earth Science Enterprise, and the NPOESS Integrated Program Office. They derive from consideration of the common issues associated with the space-based measurement of climate variables and committee concerns related to the conduct of climate research.

Recommendation 1.

Climate research and monitoring capabilities should be balanced with the requirements for operational weather observation and forecasting within an overall U.S. strategy for future satellite observing systems. The committee proposes the following specific actions to achieve this recommendation:

7  

See, for example, NRC (1998, 1999a,b).

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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  • The Executive Branch should establish a panel within the federal government that will assess the U.S. remote sensing programs and their ability to meet the science and policy needs for climate research and monitoring and the requirements for operational weather observation and forecasting.

    • The panel should be convened under the auspices of the National Science and Technology Council and draw upon input from agency representatives, climate researchers, and operational users.

    • The panel should convene a series of open workshops with broad participation by the remote sensing and climate research communities, and by operational users, to begin the development of a national climate observing strategy that would leverage existing satellite-based and ground-based components.

Recommendation 2.

The Integrated Program Office for NPOESS should give increased consideration to the use of NPOESS for climate research and monitoring. The committee proposes the following specific actions to achieve this recommendation:

  • The IPO should consider the climate research and monitoring capabilities of NPOESS along with other NPOESS requirements.

  • For those NPOESS measurements that are deemed to be critical for climate research and monitoring, the IPO should establish a science oversight team with specific responsibilities for each associated sensor suite.

  • The IPO should begin to establish plans for sensor calibration and data product validation as well as for data processing and delivery that consider the needs for climate research.

Recommendation 3.

The NASA Earth Science Enterprise should continue to play an active role in the acquisition and analysis of systematic measurements for climate research as well as in the provision of new technology for NPOESS. The committee proposes the following specific actions to achieve this recommendation:

  • NASA/ESE should develop specific technology programs aimed at the development of sustainable instrumentation for NPOESS.

  • NASA/ESE should ensure that systematic measurements that are integrated into operational systems continue to meet science requirements.

  • NASA/ESE should continue satellite missions for many measurements that are critical for climate research and monitoring.

Recommendation 4.

Joint research and operational opportunities such as the NPOESS Preparatory Project should become a permanent part of the U.S. Earth observing remote sensing strategy. The committee proposes the following specific actions to achieve this recommendation:

  • The NPP concept should be made a permanent part of the U.S. climate observing strategy as a joint NASA-IPO activity.

  • Some space should be reserved on the NPOESS platforms for research sensors and technology demonstrations as well as to provide adequate data downlink and ground segment capability.

  • NPP and NPOESS resources should be developed and allocated with the full participation of the Earth science community.

REFERENCES

National Research Council (NRC). 1998. Overview, Global Environmental Change: Research Pathways for the Next Decade. Washington, D.C.: National Academy Press.

National Research Council (NRC). 1999a. The Adequacy of Climate Observing Systems. Washington, D.C.: National Academy Press.

National Research Council (NRC), Space Studies Board. 1999b. “Assessment of NASA's Plans for Post-2002 Earth Observing Missions,” short report to Dr. Ghassem Asrar, NASA's Associate Administrator for Earth Science, April 8.

National Research Council, Space Studies Board. 2000. Issues in the Integration of Research and Operational Satellite Systems for Climate Research: II. Implementation. Washington, D.C.: National Academy Press, forthcoming.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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3.12 Issues in the Integration of Research and Operational Satellite Systems for Climate Research: II. Implementation

A Report of the Committee on Earth Studies

Executive Summary

A key objective of climate research and monitoring programs is to deliver scientifically valid knowledge that can be used by the public and by policymakers to make informed decisions about large-scale environmental issues. Because Earth's climate involves a complex interplay among the atmosphere, oceans, cryosphere, and biosphere, meeting this objective will require a comprehensive strategy that includes observations, data analysis, technology development, modeling, and data archiving and distribution. Satellite observations are an essential part of this strategy as they can record global-scale phenomena and collect information on many critical physical, chemical, and biological processes. However, there are challenges in utilizing current satellite observation programs to support climate research and monitoring. The requirements of the climate research community are sometimes at odds with the capabilities of both the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA). Further, both agencies are likely to continue to operate in a highly constrained fiscal environment. For these reasons, this report and its phase one companion, Science and Design (NRC, 2000), focus on approaches to leverage existing and planned operational and research satellite assets to meet the needs of climate research.

Operational satellite missions are designed primarily to provide observations to support short-term environmental forecasts, while research satellite missions are often designed primarily to study specific processes of scientific interest or to test new observing technologies. Obtaining long-term, well-calibrated measurements from space often falls between these agency objectives. Yet the Committee on Earth Studies believes that, while challenging, the integration of operational and research missions to advance the objectives of climate research is possible and that a unique opportunity to demonstrate such integration is presented by the National Polar-orbiting Operational Environmental Satellite System (NPOESS) and the redesigned NASA/Earth Science Enterprise (ESE) missions.

NPOESS and the NPOESS Preparatory Project (NPP) offer significant improvements over the capabilities of the two existing separate operational polar-orbiting systems: NOAA's Polar-orbiting Operational Environmental Satellites (POES) and the Department of Defense's Defense Meteorological Satellite Program (DMSP). Moreover, the redesigned NASA/ESE missions focus on critical science questions in the area of climate research, and NASA's new strategy of employing a larger number of smaller spacecraft provides a high level of flexibility.

NPOESS will collect critical data sets on variables that are not currently included in operational measurements (such as radiation budget, total ozone, wind speed and direction, ocean topography, and ocean color) and will offer improved quality for some variables now being measured (such as atmospheric moisture and temperature profiles, all-weather sea surface temperature, and vegetation indices). Moreover, the orbits of NPOESS satellites will have stable equator-crossing times, which will significantly improve the utility of the data for climate research. The next set of NASA/ESE missions will not be based on copies of the first Earth Observing System (EOS) series. Instead, they will be divided into systematic missions (i.e., emphasizing measurements of processes dominated by long-term variability) and exploratory missions (i.e., focused on specific scientific questions that can be answered with a single mission). Because systematic measurements are an essential element of the NASA/ESE strategy, special attention is being given to NPOESS. In this context, NPP is important as a testbed for the incorporation of NASA/ESE science requirements into an operational mission.

The present report emphasizes two themes. First, data stability—enabled by long-term, consistent data sets—is a critical requirement for climate research. Second, system flexibility is necessary to enable pursuit of new science objectives as well as new technology and to respond to surprises that will emerge in the Earth system. Further discussion of both themes can be found in the “Pathways” report (NRC, 1998).

NOTE: "Executive Summary" reprinted from Issues in the Integration of Research and Operational Satellite Systems for Climate Research: II Implementation, National Academy Press, Washington, D.C., 2000, pp. 1-6.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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DATA STABILITY

Because natural signals are often small, it is difficult to ascribe particular events or processes to climate change. This is especially true in the area of anthropogenic forcing, or global warming. Natural events such as the El Niño/ Southern Oscillation represent enormous, global-scale perturbations in a variety of Earth system variables, such as ocean winds and sea surface temperature, precipitation, and atmospheric carbon dioxide. For this reason, long-term, high-quality measurements are needed to discern subtle shifts in Earth's climate. Such measurements require an observing strategy emphasizing a strong commitment to maintaining data quality and minimizing gaps in coverage. Operational satellites represent a unique asset that could produce long time series with sufficient quality, although their primary mission is not climate research. NPOESS officials appear to be making significant progress toward facilitating such data records, particularly in their attempts to set stability requirements for some of the critical data sets. Currently, however, some NPOESS environmental data records do not have stability requirements, while others have incomplete or insufficient requirements. In addition, no strategy to test the stability requirements for NPOESS measurements has been defined or developed.

The committee considered data stability from three perspectives:

  • Sensor calibration and data product validation,

  • Requirements for and approaches to data continuity, and

  • Data systems.

Calibration and Validation
Findings

Long-term studies such as those needed for documenting and understanding global climate change require not only that a remote sensing instrument be accurately characterized and calibrated but also that its characteristics and calibration be stable over the life of the mission. Calibration and validation should be considered as a process that encompasses the entire system, from the sensor performance to the derivation of the data products. The process can be considered to consist of five steps. In the approximate order of performance they are (1) instrument characterization, (2) sensor calibration, (3) calibration verification, (4) data quality assessment, and (5) data product validation.

Recommendations

The committee makes the following recommendations with regard to calibration and validation:

  • A continuous and effective on-board reference system is needed to verify the stability of the calibration and sensor characteristics from the launch through the life of the mission.

  • Radiometric characterization of the Moon should be continued and possibly expanded to include measurements made at multiple institutions in order to verify the NASA results. If the new reflectance calibration paradigm is adopted (see Appendix C), then the objective of the lunar characterization program should be to measure changes in the relative reflectance as a function of the phase and position of Earth, the Sun, and the Moon rather than absolute spectral radiance.

  • The establishment of traceability by national measurement institutions in addition to the National Institute of Standards and Technology should be considered to determine if improved accuracy, reduced uncertainty in the measurement chain, and/or better documentation might be achieved, perhaps even at a lower cost.

  • The results of sensitivity studies on the parameters in the data product algorithms should be summarized in a requirements document that specifies the characterization measurements for each channel in the sensor. Blanket specifications covering all channels should be avoided unless justified by the sensitivity studies.

  • Quality assessment should be an intrinsic part of operational data production and should be provided in the form of metadata with the data product.

  • Validation, an essential part of the information system, should be undertaken for each data product or data record to provide a quantitative estimate of the accuracy of the product over the range of environmental conditions for which the product is provided.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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  • Wavelengths and bandwidths of channels in the solar spectral region should be selected to avoid absorption features of the atmosphere, if possible.

  • Calibration of thermal sensing instruments such as CERES (Clouds and the Earth's Radiation Energy System) and the thermal bands of MODIS (Moderate-resolution Imaging Spectroradiometer) should continue to be traceable to the SI unit of temperature via the Planckian radiator, blackbody technology.

Data Continuity
Findings

Continuity is concerned with more than the presence or absence of data. It includes the continuous and accurate characterization of the properties that affect the construction of the time series. The most useful data for climate research purposes are time series that are continuous and for which the characterization of error, in terms of precision and bias, is known. Such errors should be minimized as much as possible in order to detect the often small, climate-related signal.

Recommendations

The committee recommends taking the following steps to ensure data continuity:

  • A policy that ensures overlapping observations of at least 1 year (more for solar instruments) should be adopted. The IPO should examine the relation between this requirement and the launch-on-failure strategy and should include a clear definition of spacecraft or instrument failure and an assessment of still-functioning instruments.

  • Competitive selection of instrument science teams should be adopted to follow the progress of the instrument from design and fabrication through integration, launch, operation, and finally, data archiving, thereby promoting more thorough instrument characterization.

  • As instruments are developed for future missions, the IPO should make a determination of threats to the continuity of currently monitored radiances in the design requirements.

  • Out-year funding should be provided to maximize the investment made in climate and operational observing instruments.1

  • Free-flier status should be evaluated for key climate parameters such as solar radiance and sea-level altimetry whose measurement appears to be endangered by the NPOESS single-platform configuration.

  • Proven active microwave sensors should be considered for ocean vector winds, another key climate (and operational) parameter.

Data Systems
Findings

The development of an NPOESS climate data system (NCDS) represents a significant challenge. Care will be needed to ensure that the design and specifications for the data system are given a broad review prior to their implementation. In addition, special attention will be needed in areas including calibration and validation, data product continuity, data archiving, archive access, reprocessing, and cost. The NPP will serve for the early testing of instruments and data systems. It will be a joint activity between NASA and the Integrated Program Office (IPO) and as such will provide an opportunity for NPOESS to benefit from the progress NASA is making in data system development.

The development of an NCDS can clearly benefit from adopting the best elements of the current NASA and NOAA data systems. However, it will not be enough to simply expand existing facilities. A successful NCDS will also require a new vision in which innovation and competition play a central role. Observations of Earth will

1  

For climate studies, there is a need for continuing investment in sensor studies and tests—programs for operational instruments typically do not fund such activities beyond initial checkout.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
×

increase by an order of magnitude when NPOESS begins operation, which could lead to an enormous increase in our understanding of Earth. To realize this potential, the huge volumes of raw data must be converted to usable products and information. The responsibility for doing this should be given to those groups and organizations that demonstrate the vision, innovation, and expertise needed to meet the NPOESS challenge.

Recommendations

The committee recommends meeting the following basic data-systems requirements in addition to what is needed for operational processing:

  • A long-term archiving system is needed that provides easy and affordable access for a large number of scientists in many different fields.

  • Data should be supported by metadata that carefully document sensor performance history and data processing algorithms.

  • The system should have the ability to reprocess large data sets as understanding of sensor performance, algorithms, and Earth science improves. Examples of sources of new information that would warrant data reprocessing include the discovery of processing errors, the detection of sensor calibration drift, the availability of better ancillary data sets, and better geophysical models.

  • Science teams responsible for algorithm development, data set continuity, and calibration and validation should be selected via an open, peer-reviewed process (in contrast to the approach taken with the operational integrated data processing system (IDPS) and algorithms, which are being developed by sensor contractors for NPOESS).

  • The research community and government agencies should take the initiative and begin planning for a research-oriented NCDS and the associated science participation.

SYSTEM FLEXIBILITY

Because the forcing and response of Earth's climate to natural and anthropogenic variability is a complex, nonlinear process, it can be anticipated that unforeseen properties will emerge. These are the “surprises” discussed in the “Pathways” report (NRC, 1998). Scientific advances will require new observing tools. Moreover, technological advances may reduce costs or improve system performance. A rigid plan of flying exact copies of sensors will not accommodate such changes. Therefore, a way will have to be found to infuse new technology into the system while maintaining data continuity and without driving up costs. Technology insertion is defined as introduction of any new and/or improved capability (either through hardware or software innovations) into an established operational system. NASA/ESE will play an especially important role in this regard, given its experience in technology development. The committee considered the issue of system flexibility primarily from this vantage point.

Technology Insertion

Qualifying technological innovations span a wide range of implied changes and, thus, impose a wide range of risk levels on the operational performance of the system. For example, replacing a computer with a faster model that preserves the form, fit, and function of the earlier model is quite different from changing the computer's operating system or data processing algorithm. There is risk in any change to the design, but some changes may ripple throughout the system, forcing additional changes to accommodate the first. Additional risk is anathema for an operational system, for which reliability and continuity are the prime considerations. Any potential change must be examined carefully and conservatively, no matter how well justified the augmented capabilities may be from a scientific point of view.

Findings

The committee's findings are as follows:

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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  • Operational agencies exhibit a natural tendency to resist change; any candidate technology enhancement to increase the science content of data products must satisfy rigorous prequalification before being accepted into an operational payload.

  • The challenge for an operational system such as NPOESS is to accommodate technological change in a timely manner, while ensuring that the modified system will sustain operational functionality.

  • In general, the means of technology insertion into operational missions is not well determined. Indeed, there appears to be a gap between the development of instruments in the science stream and their adoption in the operational stream.

  • If the NPOESS program is to be used to support the science community as well as the operational weather agency, then a careful assessment of the pertinent science requirements must be made in the early phases of the program.

  • Technology insertion always will be subject to limitations. Any downstream change in the on-board technology must fit within the spacecraft resources (mass, power, data bandwidth, data volume, etc.) that may remain over and above the requirements of the baseline system.

  • It is likely that the development and qualification of any new measurement capability that might be required for scientific purposes would have to be funded from non-IPO sources, unless that instrument were deemed to be critical to the NPOESS operational mission. Clearly, vision and well-coordinated interagency planning are needed to sustain the development of suitable instruments in synchronization with NPOESS flight opportunities.

  • Unlike the relatively short design lifetimes of their predecessors, the NPOESS satellites are meant to have a 10-year lifetime. Whereas a 10-year design life is laudable for an ongoing operational facility, it adds further roadblocks to the process of technology insertion.

  • Under current policy, whether an instrument provides data that are important to a climate science record has no bearing on the criteria for launch of an NPOESS replacement spacecraft. Partial failure, even of a mission-critical instrument, may have such a small impact for operational weather purposes that it does not trigger a replacement launch. However, the same fault could induce degradations that would be far more significant for scientific purposes.

  • An opportunity to prove in practice the value of a candidate instrument is often a pivotal step in the effort to transform a scientific measurement into an operational tool. A satellite program such as NPP could provide such opportunities.

  • It is noteworthy that NASA's ESE Technology Development Plan does not provide for the transitioning of technology from scientific status to operational status. This fact is central to the question of technology insertion into NPOESS in support of climate or other scientific objectives. Even if a new technological innovation is proven to offer unique scientific value and is shown to be technically feasible, there are no firm plans to guide its transition onto NPOESS.

Recommendations

The IPO and NASA should strive to accommodate technological change in a timely manner, while ensuring that the modified system will sustain operational functionality. The committee's recommendations with regard to technology insertion are as follows:

  • The IPO should identify a person or group to review the system requirements and the design to ensure that both the Integrated Operational Requirements Document (IORD; IPO, 1996) and the contractor approaches will support flexibility and change.

  • NASA should provide a list of science requirements (ostensibly from the Science Plan) and climate requirements that are candidates for implementation on NPOESS.

  • The IPO should plan for the insertion of new or enhanced measurement capabilities into NPOESS that would likely have to be funded from non-IPO sources.

  • NASA ESE should implement its Technology Development Plan with firm plans linked to missions and ensure that any necessary NPOESS enabling technologies are covered in the plan.

  • NASA and the IPO should devise an approach to support announcing and accepting additional experiments on NPOESS.

Suggested Citation:"3. Summaries of Major Reports." National Research Council. 2001. Space Studies Board Annual Report 2000. Washington, DC: The National Academies Press. doi: 10.17226/10177.
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  • It is essential that the process of incorporating research requirements into NPOESS be started now and be allowed to influence the program development and risk reduction phase that is in progress, without disrupting the primary NPOESS mission. Opportunities for change after the launch are limited by the longer satellite life and longer time between launches.

REFERENCES

Integrated Program Office (IPO), National Polar-orbiting Operational Environmental Satellite System (NPOESS). 1996. Integrated Operational Requirements Document (First Version) (IORD-1) 1996. Issued by Office of Primary Responsibility: Joint Agency Requirements Group (JARG) Administrators, March 28. The updated IORD and other documents related to NPOESS are available online at < http://npoesslib.ipo.noaa.gov/ElectLib.htm.>

National Research Council (NRC). 1998. Overview, Global Environmental Change: Research Pathways for the Next Decade. National Academy Press, Washington, D.C.

National Research Council (NRC), Space Studies Board, Committee on Earth Studies. 2000. Issues in the Integration of Research and Operational Satellite Systems for Climate Research: I. Science and Design. National Academy Press, Washington, D.C.

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