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Annual Report 1991: Letter Reports Space Studies Board Annual Reportâ1991 4 Letter Reports 4.1 On The Proposed Redesign of Space Station Freedom The Space Studies Board sent the following letter and attached position statement to Adm. Richard H. Truly, Administrator of NASA, on March 14, 1991. As you know, the research utilization of a manned U.S. space station has been a subject of considerable interest to the Space Studies Board since the inception of the program. In a letter to Mr. Beggs in 1983, the Board expressed reservations about the national requirement for a manned station for supporting space science, other than life science. Since that time, station planning and design have evolved rapidly. Beginning in late 1990, and particularly after the release of the Augustine REPORT MENU Report and its recommendations for development of a U.S. space station, two of NOTICE the Board's discipline committees have become increasingly concerned about the FROM THE CHAIR research capabilities of the station as redesigned under the Congressional CHAPTER 1 mandate. In addition, the Board itself has expressed concern as to whether the CHAPTER 2 redesigned station will adequately support the research required to make CHAPTER 3 CHAPTER 4 important national decisions about long term human spaceflight. The Committee CHAPTER 5 on Microgravity Research and the Committee on Space Biology and Medicine APPENDIX were briefed by space station officials on redesign ground rules and guidelines on January 10 and February 8 of this year, respectively. On February 28, the full Board was briefed on the preliminary results of the redesign study, with the chairmen and several key members of the two committees in attendance. The briefing officials from the space station office were most generous with their time and very frank in their discussions. We thank them for their efforts. Based on this briefing and on known research requirements cited in the attached assessment, the consensus of the Board was that the inadequacy of the redesign in its present state for research was sufficiently grave that a formal Board statement expressing these views to you was in order. Please note that the Board did not formulate and does not express any opinion on the engineering feasibility of the present redesign, nor does the Board address possible reasons other than space research for proceeding with the redesigned station. file:///C|/SSB_old_web/an91ch4.htm (1 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports Enclosed is the assessment that resulted from the deliberations of the full Board, reflecting the participation of the two discipline committees. I will be happy to discuss with you any questions you might have about the Board's conclusions or the supporting rationale. We all share a common commitment to a vigorous and forward-looking national civil space research program. Signed by Louis J. Lanzerotti Chair, Space Studies Board SPACE STUDIES BOARD POSITION ON PROPOSED REDESIGN OF SPACE STATION FREEDOM Summary The United States has contemplated for many years the construction of a space station that would further a variety of national goals, one of which is space science and applications. The recent report of the presidentially appointed Advisory Committee on the Future of the U.S. Space Program, chaired by Norman Augustine, recommended that the development of a U.S. space station with research facilities must give top priority to life sciences research, with microgravity research assuming a significant but secondary role.1 The Board notes that this recommendation is fully consistent with the 1983 Space Studies Board position on the space station, as well as with the 1988 National Academy of Sciences/National Academy of Engineering report to then newly-elected President Bush.2,3 In the judgment of the Board, Space Station Freedom, at the present stage of redesign, does not meet the basic research requirements of the two principal scientific disciplines for which it is intended: (1) life sciences research necessary to support the national objective of long-term human exploration of space, and (2) microgravity research and applications. This conclusion as to the station's research capabilities is based upon an assessment of its redesign as of March 1991.4 Attachments 1 and 2 summarize the research requirements for space biology and medicine and for microgravity research and their relationship to the redesigned space station. The Space Studies Board's membership is not constituted such that it can provide an engineering judgment on the feasibility of the redesign, and therefore has not done so. file:///C|/SSB_old_web/an91ch4.htm (2 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports Research Return on Taxpayer Investment The Space Studies Board considered the quantity and quality of research that might be conducted on the proposed redesigned space station in the context of the level of investment that will be required to bring it to completion. The Board believes that neither the quantity nor the quality of research that can be conducted on the proposed station merits the projected investment. As redesigned, a maximum of $2.6 billion per year would be expended on the station to achieve an initial crew-tended capability by the mid-1990s, not including associated Space Transportation System and user costs.5 Additional funding at a comparable rate of expenditure would be required to achieve a permanently occupied capability late in the decade. In the initial, crew-tended configuration, the redesigned station would be devoted primarily to microgravity research. Life sciences research unique to the space station would not begin until the end of the decade, when the permanently occupied configuration would be established. For comparison, the 1991 NASA budget allocates roughly $102 million to microgravity research. In other words, during each of the next five years, the amount of funding devoted to space station construction for microgravity research would be approximately 20 times the level of the current research program for this discipline. In addition, the monthly cost of constructing the redesigned station would approach the annual total funding devoted to both NASA's life sciences and microgravity science and applications division during the current fiscal year. Space Research Requirements, Opportunities, and Alternatives Life Sciences Research The Augustine Committee recently concluded that the primary objective of a space station should be life sciences research.6 The Space Studies Board strongly endorses the position that a space-based laboratory is required to study the physiological consequences of long-term space flight.7,8 The Board notes that many of the fundamental problems in life sciences research involve a long period of time for their pursuit and solution. In its present form, the redesigned space station does not provide the facilities required for such research. (See Attachment 1.) Microgravity Research In the judgment of the Board, the limited microgravity research that could be conducted on the redesigned space station as currently proposed does not merit the investment. If such funds were made available, the research community would likely choose to spend them in a very different way. (See Attachment 2.) The Board believes specifically that more research progress could be achieved in a shorter period of time and at a fraction of the cost through an expanded program of Spacelab missions and of free-flyer experiments.9,10,11 file:///C|/SSB_old_web/an91ch4.htm (3 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports National Goals and Their Achievement In conclusion, the SSB recognizes that there are national considerations for building a space station other than scientific research. Included among these are the possibilities of enhancing international prestige, stimulating the nation's educational achievement, stimulating the U.S. technology base, and supporting a long-term human space exploration initiative. In the judgment of the Board, the proposed redesign of Space Station Freedom does not meet the stated national goal of enabling the life sciences research necessary to support extended human space exploration, nor does it meet the stated needs of the microgravity research community-most of whose goals could be achieved in both a more timely and more cost-effective manner by alternative means. Continued development of Space Station Freedom, as currently redesigned, cannot be supported on scientific grounds. If the present station redesign is implemented, this major national investment must be justified on the basis of considerations other than research in these two disciplines. ATTACHMENT 1 SPACE BIOLOGY AND MEDICINE RESEARCH REQUIREMENTS Requirements for conducting space biology and medicine research are described in detail in the 1987 report, A Strategy for Space Biology and Medical Science for the 1980s and 1990s.12 The major goals established in that report for this area of research are: a. "To describe and understand human adaptation to the space environment and the readaptation upon return to Earth." b. "To use the knowledge so obtained to devise procedures that will improve the health, safety, comfort, and performance of the astronauts. Specifically, we must improve our understanding of the microgravity induced alterations in physiologic and psychological processes as well as effects of radiation before long duration human exploration can be safely and effectively pursued." Critical Requirements for Conducting Space Biology and Medicine Research The Board's 1987 report13 emphasizes that a space station is pivotal to the conduct of life sciences research, and it documents the following as critical requirements for a space station: file:///C|/SSB_old_web/an91ch4.htm (4 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports 1. A dedicated life sciences laboratory with adequate scientific crew to conduct research. 2. A variable speed centrifuge of sufficient radius to accommodate small primates. 3. Sufficient numbers of experimental subjects (humans, plants, and animals) to address the stated scientific goals. 4. Sufficient laboratory resources, i.e., power, equipment, space, and atmosphere, to support the above research requirements. The Space Studies Board's Committee on Space Biology and Medicine, and the Board itself wish to emphatically emphasize that the above requirements are absolutely fundamental to the acquisition of the data necessary to determine the feasibility of long-term human space exploration. Inadequacy of the Redesigned Space Station Freedom for Space Biology and Medicine Research Requirements The Committee on Space Biology and Medicine and the Space Studies Board conclude that Space Station Freedom, in its present redesigned form, will be inadequate to meet the requirements for space biology and medicine research described above because of the following: 1. The plan to share limited power among multiple users in all laboratory modules suggests that there will be insufficient power to conduct the volume of long-term biological experiments required to support a human space exploration initiative. 2. Plans for the size and location of a centrifuge and of animal-holding facilities are insufficiently defined for proper evaluation. As emphasized in the Board's 1987 strategy report,14 an adequate centrifuge is essential to provide a 1- g control for 0-g experiments and also to explore the adequacy of artificial gravity for long-duration spaceflight. 3. The proposed crew size is insufficient to conduct the requisite experiments in a reasonable time period. 4. The absence of a dedicated life sciences laboratory will prohibit some experiments and will severely restrict most others, prolonging the acquisition of data required to answer fundamental questions related to the feasibility of long- duration human space exploration. file:///C|/SSB_old_web/an91ch4.htm (5 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports ATTACHMENT 2 MICROGRAVITY RESEARCH REQUIREMENTS The National Research Council, as well as several NASA advisory committees, has published reports over the years that specifically address the minimum research requirements for this field of space research.15,16,17 The Space Studies Board's Committee on Microgravity Research has advised the Board that, unlike research in the field of space biology and medicine, only a limited amount of the desired research in microgravity, at least over the next decade, can best be accomplished with a space station. The use of crew-tended free-flyers, drop towers, extended duration Spacelabs, and so forth, offer adequate, and in fact more viable, opportunities for the research needs in many cases. There are, however, important experiments requiring measurements and human observation and interaction over extended periods of time. The space station is a means to provide this capability. If plans proceed to conduct microgravity research on the redesigned Space Station Freedom, the Board and its Committee on Microgravity Research recommend that adequate provisions be made for supporting only those microgravity research questions that can best be addressed using a space station. The following minimum facility requirements for microgravity research aboard a space station are based on the conclusions and recommendations described in the cited reports and on recent briefings presented to the Committee on Microgravity Research and the Space Studies Board.18 Critical Requirements for Conducting Microgravity Research on a Space Station 1. Adequate power, research volume, and support space. 2. Skilled on-board scientific personnel in sufficient numbers to carry out experiments and to diagnose and correct malfunctions. 3. Suitable acceleration environment and adequate monitoring. 4. Affordable de-integration and re-integration of experiments on orbit. 5. Capability to integrate advanced techniques and instrumentation as these become available. 6. Fast turnaround for specimens that must be characterized on Earth. file:///C|/SSB_old_web/an91ch4.htm (6 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports Inadequacy of the Redesigned Space Station Freedom for Microgravity Research Needs The redesigned Space Station Freedom would be inadequate to meet the requirements of microgravity science and applications because it lacks the following: 1. A low, quiescent acceleration environment unhampered by crew activities, docking maneuvers, and other system activities necessary to sustain a permanently occupied presence. 2. A crew that would spend sufficient time working with the experiment equipment (see Attachment 1, item 3). 3. Sufficient power, data-handling capabilities, and research volume (see Attachment 1, item 1). 4. The flexibility to upgrade systems; this deficiency is especially disconcerting in the area of computers, in which obsolescence is extremely rapid. Other Issues During the crew-tended phase, NASA plans to fly Spacelab experiment hardware on the Space Station Freedom because other, newer hardware will not be available. Most of this Spacelab hardware will require manual intervention and therefore will be operable only when people are present. Unfortunately, the crew- tended phase is a time when significant acceleration disturbances will exist due to concurrent hardware integration and assembly and construction activities. Therefore, the man-tended phase will not be suitable for many microgravity experiments. Only a limited number of experiments could be run during the free- flying mode between shuttle visits during the crew-tended phase. If the bulk of the microgravity research program planned for Freedom were removed, the station would then be devoted almost exclusively to life sciences research. The benefits of this action would be that (a) the g-level on the station would not have to be strongly controlled, thus resulting in significant cost savings, (b) some low-gravity experiments (e.g., fluids handling, fire safety) could still be done on the space station, and (c) the bulk of the microgravity program could be conducted using independent, more cost-effective facilities. SPACE STUDIES BOARD file:///C|/SSB_old_web/an91ch4.htm (7 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports Louis J. Lanzerotti, Chairman, Distinguished Member of the Technical Staff, AT&T Bell Laboratories Philip Abelson, Science Advisor, American Association for the Advancement of Science Joseph A. Burns, Professor of Astronomy, Cornell University John R. Carruthers, Manager, Components Research, INTEL Andrea K. Dupree, Senior Scientist, Harvard-Smithsonian Institution Center for Astrophysics John Dutton, Dean, College of Earth and Mineral Sciences, Pennsylvania State University Larry Esposito, Associate Professor, University of Colorado James P. Ferris, Professor, Department of Chemistry, Rensselaer Polytechnic Institute Herbert Friedman, Consultant, Naval Research Laboratory Richard L. Garwin, Advisor to the Director of Research, IBM Corporation Riccardo Giacconi, Director, Space Telescope Science Institute Noel W. Hinners, Vice President for Strategic Planning, Martin Marietta Corporation James R. Houck, Professor of Astronomy, Cornell University David A. Landgrebe, Professor of Electrical Engineering, Purdue University Elliott C. Levinthal, Professor of Mechanical Engineering, Stanford University William J. Merrell, Jr., President, Texas A&M University, Galveston Richard K. Moore, Professor, Remote Sensing Labs, University of Kansas Robert H. Moser, Vice President for Medical Affairs, NutraSweet Company Norman F. Ness, President, Bartol Research Institute, University of Delaware Marcia Neugebauer, Senior Research Scientist, Jet Propulsion Laboratory Sally K. Ride, Professor/Director, California Space Institute, University of California, San Diego Robert F. Sekerka, Dean, Mellon College of Science, Carnegie Mellon University Mark Settle, Manager, The New Opportunities Group, ARCO Oil and Gas Company L. Dennis Smith, Executive Vice Chancellor, University of California, Irvine Byron D. Tapley, Director, Center for Space Research Arthur B.C. Walker, Professor of Applied Physics, Stanford University Marc S. Allen Director COMMITTEE ON SPACE BIOLOGY AND MEDICINE L. Dennis Smith, Chairman, Executive Vice Chancellor, University of California, Irvine Robert M. Berne, Alumni Professor of Physiology, University of Virginia Peter Dews, Professor of Psychology and Psychobiology, Harvard Medical School file:///C|/SSB_old_web/an91ch4.htm (8 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports R.J. Michael Fry, Head of Cancer Section, Biology Division, Oak Ridge National Laboratory Edward J. Goetzl, Professor of Rheumatic and Connective Tissue Diseases, University of California Medical Center, San Francisco Robert Helmreich, Professor of Psychology and Director, NASA/UT Aerospace Crew Research Project/The University of Texas, Austin Barry W. Peterson, Professor of Physiology, Northwestern University Clinton T. Rubin, Associate Professor/Director of Musculo-skeletal Research Laboratory, State University of New York at Stony Brook Alan L. Schiller, Professor and Chairman of Pathology, Mt. Sinai Medical Center Tom Scott, Professor of Biology, University of North Carolina, Chapel Hill William Thompson, University Professor of Botany and Genetics, North Carolina State University Fred W. Turek, Chairman, Department of Neurobiology and Physiology, Northwestern University Joyce M. Purcell Executive Secretary COMMITTEE ON MICROGRAVITY RESEARCH Robert F. Sekerka, Chairman, Dean, Mellon College of Science, Carnegie Mellon University Robert A. Brown, Head, Department of Chemical Engineering, Massachusetts Institute of Technology John R. Carruthers, Manager, Components Research, INTEL Franklin D. Lemkey, Senior Consultant Scientist, United Technologies Research Center William A. Sirignano, Dean, School of Engineering, University of California, Irvine Thomas A. Steitz, Investigator/Professor of Molecular Biophysics and Chemistry, The Howard Hughes Medical Institute/Yale University Joyce M. Purcell Executive Secretary 1Report of the Advisory Committee on the Future of the U.S. Space Program, Superintendent of Documents (GPO) December, 1990. 2Space Science Board Assessment of the Scientific Value of a Space Station and letter to NASA Administrator James Beggs, September 9, 1983. See also Space Studies Board, Testimony to U.S. Senate Subcommittee on Science, Technology, and Space, May 10, 1990. file:///C|/SSB_old_web/an91ch4.htm (9 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports 3Toward a New Era in SpaceâRealigning Policies to New RealitiesâRecommendations for President-Elect George Bush, Committee on Space Policy, NAS/NAE (NAP) 1988. 4Briefingto Committee on Microgravity Research, William Taylor, Chief Scientist, Space Station Freedom, January 10, 1991. Briefing to Committee on Space Biology and Medicine, William Taylor, Chief Scientist, Space Station Freedom, February 8, 1991. Briefing to Space Studies Board, William Raney, Special Assistant, Space Station Freedom, and John-David Bartoe, Deputy Director, Space Station Freedom Operations and Utilization, February 28, 1991. 5Conference Report 101-900, HUD and Independent Agencies, FY 1991. 6See footnote 1 above. 7A Strategy for Space Biology and Medical Science for the 1980s and 1990s (NAP) 1987. Space Studies Board Assessment: Space Biology and Medicine Researchâ1990 (in press). Space Studies Board/Committee on Space Biology and Medicine, letter to Andrew Stofan, Associate Administrator, Office of Space Station, NASA Headquarters, July 21, 1987. Space Studies Board/Committee on Space Biology and Medicine, Testimony to the U.S. Senate Subcommittee on HUD Appropriations, May 1, 1987. 8Space Studies Board letter to Joseph Alexander, Assistant Associate Administrator, Office of Space Science and Applications, NASA Headquarters, December 12, 1990. Space Station Summer Study Report, SESAC Task Force on Scientific Uses of a Space Station, NASA, March 21, 1985. Space Station Summer Study Report, SESAC Task Force on Scientific Uses of a Space Station, NASA, March, 1986. 9Microgravity Science and ApplicationsâReport on a Workshop, Panel on Microgravity Science and Applications, Solid State Sciences Committee, Board on Physics and Astronomy (NAP) 1986. Review of Microgravity Science and Applications Flight Programs, Committee to Review the Microgravity Science and Applications Flight Program, USRA, January-March, 1987. Space Studies Board Workshop on Microgravity Research, NAS Beckman Center, January 16-17, 1989. 10MaterialsProcessing in Space, Committee on Scientific and Technological Aspects of Materials Processing in Space, Space Applications Board (NAS), 1978. Industrial Applications of the Microgravity Environment, Space Applications Board (NAP) 1988. 11See footnote 8 above. 12See footnote 7 above. file:///C|/SSB_old_web/an91ch4.htm (10 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports 13A Strategy for Space Biology and Medical Science for the 1980s and 1990s (NAP) 1987. Space Studies Board Assessment: Space Biology and Medicine Researchâ1990 (in press). Space Studies Board/Committee on Space Biology and Medicine, letter to Andrew Stofan, Associate Administrator, Office of Space Station, NASA Headquarters, July 21, 1987. Space Studies Board/Committee on Space Biology and Medicine, Testimony to the U.S. Senate Subcommittee on HUD Appropriations, May 1, 1987. 14See footnote 13 above. 15Space Studies Board letter to Joseph Alexander, Assistant Associate Administrator, Office of Space Science and Applications, NASA Headquarters, December 12, 1990. Space Station Summer Study Report, SESAC Task Force on Scientific Uses of a Space Station, NASA, March 21, 1985. Space Station Summer Study Report, SESAC Task Force on Scientific Uses of a Space Station, NASA, March, 1986. 16Microgravity Science and ApplicationsâReport on a Workshop, Panel on Microgravity Science and Applications, Solid State Sciences Committee, Board on Physics and Astronomy (NAP) 1986. Review of Microgravity Science and Applications Flight Programs, Committee to Review the Microgravity Science and Applications Flight Program, USRA, January-March, 1987. Space Studies Board Workshop on Microgravity Research, NAS Beckman Center, January 16-17, 1989. 17MaterialsProcessing in Space, Committee on Scientific and Technological Aspects of Materials Processing in Space, Space Applications Board (NAS), 1978. Industrial Applications of the Microgravity Environment, Space Applications Board (NAP) 1988. 18Briefing to Committee on Microgravity Research, William Taylor, Chief Scientist, Space Station Freedom, January 10, 1991. Briefing to Committee on Space Biology and Medicine, William Taylor, Chief Scientist, Space Station Freedom, February 8, 1991. Briefing to Space Studies Board, William Raney, Special Assistant, Space Station Freedom, and John-David Bartoe, Deputy Director, Space Station Freedom Operations and Utilization, February 28, 1991. 4.2 On the NASA Earth Observing System The Space Studies Board sent the following letter and attached position to Adm. Richard H. Truly, Administrator of NASA, on July 10, 1991. We are pleased to transmit to you two new Space Studies Board reports: file:///C|/SSB_old_web/an91ch4.htm (11 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports Space Studies Board Position on the NASA Earth Observing System, and a prepublication copy of a related report, Assessment of Satellite Earth Observation Programsâ1991, by the Board's Committee on Earth Studies. We will forward a bound copy of the latter report as soon as it is printed. Copies of these reports will be sent to cognizant executive agency and congressional offices tomorrow morning and subsequently to the media. Do not hesitate to call me if you have any questions about either of these reports. Signed by Louis J. Lanzerotti Chair, Space Studies Board SPACE STUDIES BOARD POSITION ON THE NASA EARTH OBSERVING SYSTEM Introduction Complex scientific questions and major policy issues together provide the motivation for a comprehensive attempt to improve our understanding of the earth system. Progress in the scientific disciplines concerned with the Earth and its evolution on time scales of decades to centuries has revealed critical questions that can be resolved only by studying the entire system, concentrating especially on interdisciplinary questions that reflect the complex interactions among the system's components. Policy issues arise because human activities and natural processes are changing the environment in ways that may be significant to the future health and habitability of the Earth. The scientific and policy issues have been well documented in a series of National Research Council (NRC) and government reports over the past decade. These factors and the need for accurate and comprehensive scientific information on which to base environmental policy decisions have led to the creation of a number of international and national research initiatives, including the U.S. Global Change Research Program. According to the report Our Changing Planet: The FY 1992 U.S. Global Change Research Program, by the federal interagency Committee on Earth and Environmental Sciences (1991), The central goal of the U.S. Global Change Research Program (USGCRP) is to establish the scientific basis in support of national and international policy making relating to natural and human- induced changes in the global Earth system by: ⢠Establish[ing] an integrated, comprehensive, long-term program file:///C|/SSB_old_web/an91ch4.htm (12 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports of documenting the Earth system on a global scale. ⢠Conduct[ing] a program of focused studies to improve our understanding of the physical, geological, chemical, biological and social processes that influence Earth system processes; [and] ⢠Develop[ing] integrated conceptual and predictive Earth system models. (p. 1) Even before the creation of the USGCRP in 1989, these considerations motivated the community of earth scientists concerned with global change to develop plans for research, observation, and modeling activities to improve scientific understanding. At the center of this set of activities was the Earth Observing System (EOS), a major initiative that has now been incorporated into the USGCRP. As currently proposed, EOS will involve a number of spacecraft carrying instruments designed to produce, across a wide spectrum of electromagnetic frequencies, detailed observations of the physical variables that reveal the state, evolution, and interactions of the atmosphere, oceans, and land surface, as well as the biological communities on the land and in the sea. The EOS program is planned to span almost two decades, beginning with the launch of the first spacecraft in 1998. It will generate unprecedented amounts of data that must be converted into information and understanding, and ultimately, used to develop techniques for prediction. These complex data management functions will be performed through the EOS Data and Information System (EOSDIS), which will provide computing and networking facilities for research; processing, distribution, and archiving of EOS and related data; and spacecraft command and control functions. In addition to developing the flight components and the EOSDIS, the EOS program also supports interdisciplinary research teams, 28 of which are already established, to study focused issues that range across the relevant earth-related sciences. Other nations, notably Japan, Canada, and the member states of the European Space Agency, have made commitments for significant contributions to the total EOS program, including instruments and ground facilities. In short, EOS, as currently planned, will be the largest single component of the most ambitious scientific enterprise ever undertaken. Nevertheless, there are observations critical to understanding the earth system that cannot be obtained by the instruments proposed for the polar- orbiting, sun-synchronous EOS spacecraft. Thus EOS itself is considered by NASA to be part of a broader satellite remote sensing initiative-Mission to Planet Earth-that will augment EOS with a number of focused missions, called Earth Probes, in other orbits. Possible missions under consideration include measurements of the Earth's radiation budget, an accurate determination of global land-surface topography, synthetic aperture radar observations of the Earth, and measurements of the Earth's gravity and magnetic fields. NASA plans that Mission to Planet Earth will eventually include geosynchronous satellites taking continuous synoptic observations of the planet. Several other NASA research missions being prepared for launch prior to the EOS time frame, such as the Upper Atmosphere Research Satellite and the Ocean Topography Experiment (TOPEX/Poseidon), also will make important contributions to our understanding of the Earth. file:///C|/SSB_old_web/an91ch4.htm (13 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports These elements of NASA's Mission to Planet Earth are or will be augmented significantly by the operational environmental spacecraft of the National Oceanic and Atmospheric Administration (NOAA) in polar and geostationary orbits, by the Landsat system operated on a commercial basis by the Earth Observation Satellite (EOSAT) Company, as well as by certain declassified data from operational and experimental satellites of the Department of Defense. Internationally, there are numerous experimental, operational, and commercial spacecraft already in orbit or under construction by the European Space Agency and its individual member states in western Europe, and by Canada, Japan, the Soviet Union, China, and India that can be expected to contribute to the global research and monitoring effort. Scientific Significance of the EOS Program The scientific questions motivating and shaping studies of the Earth generally, and the EOS program specifically, are very challenging. They are different in some respects from the questions that motivate much of space research, for they concern the behavior of an entire complex system, the role of feedback and interfacial processes in controlling its evolution, and the development of parameterizations that can be used to make long-term statistical projections. It will take several decades, at least, to answer these questions with confidence, even though the elements of critical policy issues may become clear much sooner. Based on the research priorities established by the earth science research community, NASA (1991) has articulated the following specific measurement objectives for EOS in the EOS Reference Handbookâ1991: Global distribution of energy input to and energy output from the Earth. Structure, state variables, composition, and dynamics of the atmosphere from the ground to the mesopause. Physical and biological structure, state, composition, and dynamics of the land surface, including terrestrial and inland water ecosystems. Rates, important sources and sinks, and key components and processes of the Earth's biogeochemical cycles. Circulation, surface temperature, wind stress, sea state, and the biological activity of the oceans. file:///C|/SSB_old_web/an91ch4.htm (14 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports Extent, type, state, elevation, roughness, and dynamics of glaciers, ice sheets, snow, and sea ice. Global rates, amounts, and distribution of precipitation. Dynamic motions of the Earth as a whole, including both rotational dynamics and the kinematic motions of the tectonic plates. Not all of these scientific objectives will be fully addressed in the EOS program, however. These and other deficiencies in the planned observations are discussed in the Space Studies Board's Committee on Earth Studies report, Assessment of Satellite Earth Observation Programsâ1991 (Space Studies Board, 1991), as well as in The U.S. Global Change Research Program: An Assessment of FY 1991 Plans (National Research Council, 1990). In addition to the many contributions to the traditional earth sciences now expected, the EOS program will have other significant impacts. It will stimulate the development of the new earth system science that transcends today's discipline-specific emphasis on components of the earth system and that produces a truly global view and comprehensive understanding of our planet. There will be strong impacts on the evolution of biological and ecological sciences, because the development of explicit models of the interaction of biological systems with the physical environment will be pursued. The EOS program is designed to provide an empirical base of information about the distribution and large-scale evolution of biological systems that may be expected to inspire the development of a theoretical understanding of macroscopic biology. Moreover, understanding the interactions of all the components of the earth system could provide a prototype for the development of a theory of dynamical systems considerably richer than is now available. Among the most interesting issues are the interactions of processes on diverse spatial and temporal scales, the origins of catastrophic transitions between quasi-stable states of the system, and the characteristics of a system that determine its limiting behavior. The earth system models that will evolve from global data are also expected to stimulate the development of techniques for predicting the statistics of chaotic states for which deterministic prediction is impossible. Finally, the earth system computer models used to simulate future climate patterns and other large-scale processes will permit socioeconomic studies that require quantification of human interaction with the environment. EOS in the Broader Context As proposed, EOS is of unprecedented complexity and magnitude for two reasons. First, meeting the scientific requirements to observe and understand the interactions of earth system components requires integrated, and in some cases file:///C|/SSB_old_web/an91ch4.htm (15 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports simultaneous, measurements of suites of variables. Thus the science requirements mandate spatially comprehensive observations of the Earth that produce information relevant to a broad spectrum of questions. Second, the importance of the policy issues associated with the possibility of accelerating global change requires that many elements of the observation program be developed through parallel, rather than incremental, endeavors. This approach must be managed with both innovation and rigor to ensure that each component of the proposed EOS program will be successful and that the program will achieve its objectives within a reasonable and well-defined cost. Even so, the resources for EOS, as currently proposed, could become a significant fraction of the nation's civil space research program. There is an obvious danger that other important U.S. research initiatives may be compromised by the demands of EOS. The board notes that a 1988 NRC report, Toward a New Era in Space-Realigning Policies to New Priorities, and the Report of the Advisory Committee on the Future of the U.S. Space Program (NASA, 1990) both recommended that major NASA programs such as EOS and the human exploration of space be considered and evaluated as additions to a base space research effort. The SSB reaffirms this recommendation. The national resources required to execute the proposed EOS program will be considerable, and there must be confidence that the investment will produce the achievements that are now expected. The EOS program will provide information and knowledge that could be used to address a number of concerns related to national well-being. The EOSDIS, in particular, will provide the capability to synthesize information for a broad range of applications, including the preservation of diverse ecosystems, the enhancement of agricultural productivity, and the improved management of our natural resources. The EOS program can help strengthen national and global security, in part because it will provide a significant portion of the scientific basis with which to address the potentially contentious political and economic issues related to human influences on global change, and in part because it will draw scientists and others from around the world to work in concert to understand, preserve, and perhaps improve our environment. There are other benefits that could flow from EOS. It will stimulate the development of technological capability and new approaches to the management of large and complex collections of data and information. As an international effort, EOS can symbolize U.S. leadership in addressing global environmental problems. The sensors of the EOS program that are aimed at studying the Earth's surface and troposphere can augment current operational spaceborne systems. The necessary interfaces of the EOS program, with the relevant government agencies and the appropriate private-sector users, must be an integral part of EOS program planning if the broader applications of EOS data are to be realized. Given the planned long duration of the EOS program, such sensors may in some cases become the operational systems of choice, once their capabilities have been demonstrated. file:///C|/SSB_old_web/an91ch4.htm (16 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports Conclusions and Positions The Space Studies Board (SSB) position on the EOS program is based in part on an analysis performed by its Committee on Earth Sciences (CES) in an unpublished internal report to the board, as well as on the committee's full report, Assessment of Satellite Earth Observation Programsâ1991 (Space Studies Board, 1991). This assessment by the board also takes account of the conclusions and recommendations described in The U.S. Global Change Research Program: An Assessment of FY 1991 Plans (National Research Council, 1990), and other previous reports of the SSB and the NRC cited in the bibliography. In conducting this review, the SSB did not evaluate the cost-effectiveness of the proposed EOS program or compare it to other potential options. The board accepts the conclusions and recommendations on these issues made in the report, The U.S. Global Change Research Program: An Assessment of FY 1991 Plans, in the preparation of which members of the board and its Committee on Earth Studies played an active part. The board notes as well that questions of cost and comparisons to other mission scenarios are currently being independently reviewed by the Earth Observing System Engineering Review Advisory Committee, at the request of the Office of Management and Budget. The conclusions and positions presented in this position paper simultaneously inspire confidence and generate concern. Clearly, the planners of the EOS program are attempting to incorporate the advice and key recommendations of the research community. As it now stands, the program serves well the scientific strategies recommended by the SSB and other advisory bodies. But EOS is an immense undertaking, and there are aspects of it that are not, and cannot be, completely determined or envisioned now. The flight configurations and the design of the data and information system are not yet fully defined. Moreover, the management of EOS must be sufficiently flexible to take advantage of continuing evolution over the program's lifetime in scientific understanding and requirements, and in technological capabilities. There is concern that the present program does not institutionalize such flexibility. The scope of the program will require the development and implementation of sophisticated and innovative management principles and structures at the project, agency, interagency, and international levels. These issues are all significant, because answers to the scientific questions that drive EOS are central to understanding, and possibly ameliorating, global change and its impacts. The Space Studies Board concludes that the EOS program is a potentially valuable initiative to serve the best interests of science and the nation. The component parts of EOS together address complex scientific questions whose answers are important for establishing the most effective and appropriate policies related to global change. Because of the high priority of the overall science objectives that will be addressed by the EOS program, the rationale for flying suites of instruments that will measure these objectives, and the potential importance of the effects of global change on humanity, the SSB endorses the file:///C|/SSB_old_web/an91ch4.htm (17 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports program. The acquisition of a long-term, continuous, and integrated series of data on the components of the earth system and their interactions is the critical scientific motivation for EOS. Nevertheless, many important issues regarding EOS still exist and must be satisfactorily addressed in the months and years ahead. These concerns are related to matters involving (1) the development of the spacecraft configurations required for acquisition of the scientific data; (2) the design and evolution of the data and information management system; and (3) the long-term management plan to ensure program success for the planned scientific, applications, and policy purposes. After reviewing the documents prepared by the Committee on Earth Studies and the other reports cited above, the board has adopted the following conclusions and positions at this time: While parts of the EOS program require substantially more definition than is available at present, the SSB concludes three things about the planned implementation. First, a set of integrated instrumentation directed toward the highest-priority science is required. Second, scientific and technological evolution in the program must be implemented in a way that preserves the long-term continuity of the measurements. Third, the instrumentation selected for development for the second series of spacecraft proposed by NASA should be justified by the scientific objectives, but NASA should consider the optimum spacecraft and orbit configuration in light of all the scientific requirements. NASA and the scientific community should continue to examine the conceptual and architectural structures for the EOS Data and Information System (EOSDIS) to ensure that it will effectively serve the science and applications communities, that it will stimulate research and education in the sciences concerned with global change, and that it will be configured to take advantage of evolving technological capabilities. NASA and other entities of the federal government should give continuing attention to the optimum structures and policies for managing the EOS program. The scope and significance of the program, as well as its role as a key component of the U.S. Global Change Research Program, present a major management challenge. As it develops and proceeds, EOS can be strengthened through continuing review by the earth science and space research community. Management of the EOS program should institutionalize the flexibility necessary to accommodate evolution in understanding of the key scientific questions, and in technological capabilities for observation of the Earth from space. A process should be established so that EOS can take advantage of changes in spacecraft designs, instruments, and telemetry and communication systems, as well as in the hardware and software used in the data and information system, without sacrificing the central objective of collecting long- term, continuous data sets. file:///C|/SSB_old_web/an91ch4.htm (18 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports Planning for EOS should continue to take specific account of the possibilities of failure in the components of the flight and communication systems. The EOS architecture and design should provide sufficient redundancy and flexibility to create alternatives that can be activated to mitigate the effects of failures and provide for continuity in observations. Provisions should be considered for in-flight reprogramming of the critical parts of spacecraft, instruments, and onboard control and data systems. The federal Committee on Earth and Environmental Sciences should carefully exercise its responsibility to ensure that EOS is integrated with the other components of the U.S. Global Change Research Program and other relevant federal programs, including the operational satellites of the National Oceanic and Atmospheric Administration, to maximize the effectiveness of all aspects of the research. Much more attention should be devoted to the issue of how to transfer the new scientific understanding to the federal and private organizations that will develop, and be affected by, policy decisions that might arise from the research results. In particular, NASA should ensure that the EOSDIS is designed and organized to facilitate dissemination of the knowledge gained from EOS to federal agencies and private organizations, and should assist in the effective conversion of this information into sound policy decisions. NASA should encourage the use of appropriate EOS data for applications in the operational and private sectors once the sensors have been validated in flight, and initial planning should involve those sectors. Research into the applications that will be made possible with the information derived from the new suite of EOS sensors should be supported by NASA and other federal agencies involved in such applications. The EOS initiative must be viewed not as a project to construct and launch a number of spacecraft, but as a process to create a national and international capability for observing the Earth and providing the data and information necessary to address critical scientific questions. A number of important unresolved issues involving EOS science and system configuration still remain. The Space Studies Board will therefore continue to review the EOS program as it progresses. Select Bibliography Committee on Earth and Environmental Sciences (1991) Our Changing Planet: The FY 1992 U.S. Global Change Research Program, Office of Science and Technology Policy, Washington, D.C. file:///C|/SSB_old_web/an91ch4.htm (19 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports National Aeronautics and Space Administration (1990) Report of the Advisory Committee on the Future of the U.S. Space Program, Advisory Committee on the Future of the U.S. Space Program, U.S. Government Printing Office, Washington, D.C. National Aeronautics and Space Administration (1991) EOS Reference Handbook-1991, NASA-Goddard Space Flight Center, Greenbelt, Md. National Research Council (1988) Toward a New Era in Space-Realigning Policies to New Priorities, National Academy Press, Washington, D.C. National Research Council (1990) The U.S. Global Change Research Program: An Assessment of FY 1991 Plans, Committee on Global Change, National Academy Press, Washington, D.C. Space Applications Board (1985) Remote Sensing of the Earth from Space: A Program in Crisis, National Academy Press, Washington, D.C. Space Science Board (1982) Data Management and Computation-Volume 1: Issues and Recommendations, Committee on Data Management and Computation, National Academy Press, Washington, D.C. Space Science Board (1982) A Strategy for Earth Science from Space in the 1980's-Part I: Solid Earth and Oceans, Committee on Earth Sciences, National Academy Press, Washington, D.C. Space Science Board (1985) A Strategy for Earth Science from Space in the 1980's and 1990's-Part II: Atmosphere and Interactions with the Solid Earth, Oceans, and Biota, Committee on Earth Sciences, National Academy Press, Washington, D.C. Space Science Board (1986) Remote Sensing of the Biosphere, Committee on Planetary Biology, National Academy Press, Washington, D.C. Space Science Board (1988) Strategy for Earth Explorers in Global Earth Sciences, Committee on Earth Sciences, National Academy Press, Washington, D.C. Space Studies Board (1991) Assessment of Satellite Earth Observation Programs-1991, Committee on Earth Studies, National Academy Press, Washington, D.C., in press. 4.3 On Research Uses of LANDSAT file:///C|/SSB_old_web/an91ch4.htm (20 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports The Committee on Earth Studies sent the following letter to Dr. Shelby Tilford, Director of NASA's Earth Science and Applications Division, and Mr. Russell Koffler, NOAA Deputy Assistant Administrator of the National Environmental and Space Data and Information Service, on September 12, 1991. At the May 1991 meeting of the Space Studies Board's (SSB) Committee on Earth Studies (CES), there was an extensive discussion of the current status and future uncertainty regarding the Landsat program. At that meeting, several invited participants from the government, notably from the Office of Management and Budget, and from the House Committee on Science, Space, and Technology, expressed an interest in receiving the views of the CES on the research applications of the Landsat program and its role in the broader satellite Earth observations context. This letter provides a focused analysis based in large part on the previous advice given on this program by the CES, SSB, and other National Research Council (NRC) advisory groups. The Terms of Reference for this report are to: 1. review the research uses of the Landsat program, referring both to past examples and future needs; 2. examine the research role of the Landsat program in the broader land remote sensing context; 3. identify the difficulties associated with the effective use of Landsat data for research; and 4. provide recommendations for addressing those difficulties. The committee has been informed that the House Committee on Science, Space, and Technology is planning to introduce legislation regarding the Landsat program in mid-September, and a decision regarding the future of Landsat is expected to be made by the National Space Council and the Office of Management and Budget before the end of September. Given the short schedule for the committee's review, this letter is limited to issues directly related to the basic and applied civil research uses of Landsat and draws heavily on past NRC advice. The rest of this letter is organized according to the Terms of Reference set forth above, and the committee's summary conclusions and recommendations appear in the final section. RESEARCH USES OF LANDSAT For almost twenty years the Landsat program has documented both natural and anthropogenic changes on the world's land surface. An uninterrupted file:///C|/SSB_old_web/an91ch4.htm (21 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports stream of observations has provided revealing imagesâalmost three million to dateâof the natural environment and the effects of our actions upon it. The many important uses of Landsat have been well documented, most recently at a congressional hearing, on "Military, Civilian, and Commercial Applications of the Landsat Program," held jointly by the House Committee on Science, Space, and Technology and the Permanent Select Committee on Intelligence on June 26, 1991 (referred to below as the "joint hearing"). In this section the Committee briefly reviews the research applications of the Landsat system, primarily as they have been discussed in earlier NRC reports. Basic Research As discussed in past SSB reports, Landsat data have been used to support high-priority basic research objectives in geology, hydrology, glaciology, global biology, ecology, and biogeochemical cycles. Additional research areas in which the Landsat program has been instrumental, but that were not covered in the SSB reports, include agronomy, forestry, geography, and soil science. Landsat data are important to achieving the primary science objectives for continental geology from space, which were established by the CES in its report, A Strategy for Earth Science from Space in the 1980's-Part I: Solid Earth and Oceans (Space Science Board, National Academy Press, Washington, D.C., 1982). These objectives, which remain valid today, are (1) to determine the global distribution and composition of continental rock units; (2) to determine the morphology and structural fabric of the Earth's land surface; and (3) to measure temporal changes in geological conditions at the Earth's surface. Landsat observations have been and continue to be used to address some of the research objectives for the related areas of hydrology and glaciology, as proposed by the committee in A Strategy for Earth Science from Space in the 1980's and 1990's-Part II: Atmosphere and Interactions with the Solid Earth, Oceans, and Biota (Space Science Board, National Academy Press, Washington, D.C., 1985). These objectives have included, in particular, the measurement of various land-surface characteristics that control hydrologic responses and are affected by hydrologic change, as well as the horizontal extent of the world's snow and ice cover. Perhaps most importantly, Landsat data have been used extensively for the study of global biology, ecology, and biogeochemical cycles. In particular, the committee's 1985 report and another report, Remote Sensing of the Biosphere (Committee on Planetary Biology, Space Science Board, National Academy Press, Washington, D.C., 1986), identified several objectives for research on land- surface vegetation and the study of wetlands for which Landsat observations have been especially well suited. These objectives include the measurement of total area covered and the geographic distribution of major biomes and coastal wetlands, and measurement of the rate of change of distribution of major biomes and of annual vegetation production. file:///C|/SSB_old_web/an91ch4.htm (22 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports A survey of citations in seven databases performed by our committee in August 1991 showed that since 1972, the Landsat program and its data have been discussed in over 13,000 research articles in a broad range of disciplines. The databases surveyed were those of the National Technical Information Service and the Public Affairs International Service, as well as Georef, Geobase, Environmental Bibliography, Meteorological/Geoastrophysical Abstracts, and Water Resources Abstracts. With regard to basic scientific research needs in the future, the Landsat program has provided an irreplaceable two-decade data set on land-surface processes, which is of critical importance to the U.S. Global Change Research Program (USGCRP) and the International Geosphere-Biosphere Program (IGBP). As noted in the committee's most recent report, Assessment of Satellite Earth Observation Programsâ1991 (Space Studies Board, National Academy Press, Washington, D.C., 1991), the effective "integration of the Landsat data into the research framework of the [NASA] Mission to Planet Earth and USGCRP is especially important." The Landsat program provides a baseline database that can be used to detect signal changes and climate change impacts to the land surface on regional scales. The importance of Landsat data to global change research was underscored by the testimony of Dr. Robert Corell, assistant director for geosciences at the National Science Foundation and chairman of the interagency Committee on Earth and Environmental Sciences' (CEES) Working Group on Global Change, at the joint hearing. Applied Research The program has also had a major impact in applied research. In a report of the NRC's Space Applications Board (SAB), Remote Sensing of the Earth from Space: A Program in Crisis (Space Applications Board, National Academy Press, Washington, D.C., 1985), the SAB found that "the Earth remote sensing [Landsat] program has demonstrated that the timely acquisition of data from satellites can result in significant social, economic, and scientific benefits," and that the "potential for the future is even greater." The report documented a number of representative examples of the applications of Landsat data and recommended that "Earth remote sensing should be an established and significant part of the nation's civil space enterprise." Landsat data have become increasingly important in applied research and in the rapidly growing use of Geographic Information Systems (GISs). The far- reaching potential for use of Landsat data in environmental protection, resource management, and numerous socioeconomic applications was amply documented at the joint hearing in the testimony given by Dr. Dallas Peck, director of the U.S. Geological Survey; David Thibault, executive vice president of the Earth Satellite Corporation; Steven Sperry, manager of marketing at ERDAS, Inc.; and Lawrence Ayers, vice president for International Marketing at Intergraph Corp. file:///C|/SSB_old_web/an91ch4.htm (23 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports In summary, the committee concludes that Landsat observations have provided invaluable environmental information important for both basic research and applications, that the needs and uses for these data have grown steadily, and that they may be expected to continue to increase in the future. Moreover, as discussed in the next section, the Landsat system's capabilities have not been duplicated by other remote sensing systems, nor will they be replaced by any planned systemâU.S. or foreignâbefore the end of the decade. LANDSAT IN THE BROADER LAND REMOTE SENSING CONTEXT Although the existing and potential applications of Landsat data provide a compelling incentive for the future continuation of the program, it is important to understand the role of the Landsat system in the overall land remote sensing context. Just as there have been significant advances in and expansion of the basic and applied research uses of Landsat, there have been concomitant advances in land remote sensing technologies and programs, not only in the United States, but internationally. The current and planned land remote sensing systems are reviewed here and compared with the Landsat-6 system, which will fly a Thematic Mapper with 30-m resolution and an Enhanced Thematic Mapper with 15-m resolution. Table 1 provides a summary of all current and planned land remote sensing capabilities comparable to those of Landsat-6 that are expected to be launched prior to the launch of the NASA Earth Observing System (EOS) in the latter part of this decade. Not included in this comparative overview are lower- resolution sensors such as the Advanced Very High Resolution Radiometer onboard the NOAA polar-orbiting operational environmental spacecraft, or airborne and Shuttle-operated land remote sensing systems. These types of sensors are considered complementary rather than comparable, because of either lower resolution, or limited geographic or temporal coverage. Also not included in this list are several Soviet systems, some of which have high spectral and spatial resolution, but whose data are not available at this time on a consistent basis or in a digitized format. TABLE 1 Major Characteristics of Selected Land Remote Sensing Systems Landsat-6 SPOT MOS- IRS-1,2 JERS- ADEOS U.S.A. France 1,2 India 1,2 Japan India Japan (1995) (1992) Visible/Near- 5 3 4 4 3 5 Infrared Bands file:///C|/SSB_old_web/an91ch4.htm (24 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports Shortwave 2 1 (SPOT- (none) (none) 4 (none) Infrared 4, Bands 1995) Thermal 1 (120 m) (none) (none) (none) (none) (none) Infrared Bands Spatial 15 m 10 m 50 m 36 m 18 x 24 8-16 m Resolution 30 m 20 m 73 m m of Images Swath Width 185 km 60-80 km 100 km 148 km 75 km 80 km Equatorial 10:30 a.m. 10:30 a.m. 10:30 10:30 10:30 10:30 Crossing a.m. a.m. a.m. a.m. Time (+/- 15 mins) Repeat Cycle 16 days 26 days (1- 17 days 22 days 44 days 41 days 5 days with pointing) Orbital 98.2° 98.7° 99.1° polar 98° 98.6° Inclination Notes: SPOT - Satellite Pour l'Observation de la Terre MOS - Marine Observation Satellite IRS - Indian Remote Sensing Satellite JERS - Japanese Earth Resources Satellite ADEOS - Advanced Earth Observing Satellite Years in parentheses indicate planned launch dates. As Table 1 indicates, there are at least five other land remote sensing systems, with sensors observing in the visible to infrared portions of the spectrum, that will be operating in the time frame of Landsat-6 and its immediate successor. Each of these systems shares several characteristics with Landsat-6, but none is identical. The other systems differ most significantly in their complete lack of thermal infrared coverage, their narrow swath widths, and, for the JERS and ADEOS systems, long repeat cycles. Thermal infrared observations provide data on surface geology, soil moisture, flooding, water temperature, and coastal currents. Landsat also has better shortwave infrared coverage than all but the planned JERS system. These bands are important for observing, among other things, vegetation characteristics such as biomass, plant stress, and deforestation. The broader swath width (and reduced spatial resolution) of Landsat makes it less costly to acquire and process data for large geographical areas. Finally, only the SPOT series can provide more frequent and timely coverage than Landsat because of SPOT's pointable sensor capability. Although the technical comparison of Landsat to the other pre-EOS land remote sensing systems demonstrates its unique features, the most important features are not technical. The Landsat program has archived data for 13 years file:///C|/SSB_old_web/an91ch4.htm (25 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports longer than has the second-oldest system, SPOT, and it therefore offers the longest uninterrupted satellite data set for global change research. The other systems' data sets, while partially analogous, are not directly intercomparable with Landsat data. Even more importantly, all the other high-resolution, land- remote-sensing systems are operated by other nations, which means that the U.S. government and research community have only an indirect influence on the technical, programmatic, and policy decisions regarding the characteristics, cost, and availability of the data. In the latter part of the decade, there are a number of land remote sensing instruments planned as part of NASA's EOS program, in cooperation with the European Space Agency, Canada, and Japan. Although the configuration and instrument payload of the NASA EOS spacecraft have not yet been finalized, it is possible to make some preliminary comparisons with Landsat. The EOS parameters for climate research, and therefore only four of the planned sensorsâthe Moderate-Resolution Infrared Spectrometer (MODIS), the Multi- Angle Imaging Spectro-Radiometer (MISR), the High-Resolution Imaging Spectrometer (HIRIS), and the Advanced Spaceborne Thermal Emission and Reflection (ASTER) Radiometerâwill collect land-surface data in the visible and infrared portions of the spectrum. The highest spatial resolution capabilities of the MODIS and the MISR will be approximately 250 m, and so they are not directly comparable to Landsat. The two EOS instruments that would have features similar to Landsat-6 are the HIRIS and the ASTER. Although the HIRIS is expected to have 192 spectral bands in the 0.4- to 2.45-micron wavelength region, the instrument would have a swath width of only 24 km and would be used for local area process studies, rather than for regional or global coverage. The narrow swath width would allow the HIRIS to view the entire Earth surface only every 138 days. Moreover, the HIRIS will not fly on the initial EOS spacecraft, and its development under that program is uncertain. The ASTER instrument, which is being designed and built by Japan as a contribution to the NASA EOS program, would provide data most comparable to Landsat data. The ASTER is expected to have three visible and near-infrared bands at 15-m resolution, six shortwave infrared bands at 30-m resolution, and five thermal infrared bands at 90-m resolution. The swath width would be only 60 km, however, with a pointable cross-track range of 106 km. A significant difference for all of the EOS instruments may be in the spacecraft crossing time, which is currently planned for 1:30 p.m. The afternoon crossing time favors atmospheric and oceanic research objectives rather than the study of land- surface processes, which are better observed in the morning when there is statistically less cloud cover that might obscure the ground surface. Thus, even if the follow-on to Landsat-6 were to contain no additional technical improvements, it would still provide a unique observational capability and continuity of this important data set well into a third decade. The committee must point out, however, that copying 1970's technology in the mid-1990s, even though serving a valuable data-collection function, will not take full advantage of file:///C|/SSB_old_web/an91ch4.htm (26 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports current technological capabilities. Although the committee has not been able to review directly competitive technical options for improving the space segment of the Landsat system, it is aware of a number of proposed systems that may be able to provide more effective alternatives. The committee therefore recommends that the government, in considering alternative and innovative technologies for collecting a fully comparable data set into the next century, place the highest priority on maintaining uninterrupted continuity of the Landsat data set, even if that necessitates flying only a slightly improved version of Landsat-6. IMPEDIMENTS TO EFFECTIVE UTILIZATION OF LANDSAT DATA Despite the demonstrated success of Landsat technology and the well- documented importance of both the current and historical data to a host of applications, the committee has identified several factors that significantly inhibit more effective use of those data. These impediments may be divided into three categories: those associated with the perennial uncertainty about the long-term continuation of Landsat observations, those related to the cost of the data, and those concerning effective archiving of the data. As noted in the committee's most recent report (Assessment of Satellite Earth Observation Programsâ1991, Space Studies Board, 1991), uncertainty about the future continuation of the Landsat program began almost immediately upon its transfer from NOAA to the Earth Observation Satellite (EOSAT) Company in September 1985. Under the terms of the transfer, the government agreed to subsidize the operation of Landsat-4 and -5, as well as the procurement and launch of Landsat-6 and -7. For several years following the transfer, however, the budgets proposed by the Office of Management and Budget did not provide the funds to implement the transition plan. After much debate, the funding was restored each year by Congress. These funding uncertainties caused delays and cost overruns in the development of Landsat-6 and postponed the development of Landsat-7. Potential end users consequently were unwilling to invest resources necessary either to learn how to use the data, or to develop the infrastructure to process the data. This uncertainty, unfortunately, still exists. In 1990, at the request of Dr. D. Allan Bromley, assistant to the President for science and technology, the NRC undertook a special study to review the U.S. Global Change Research Program as described in the President's FY 1991 budget, and to address several specific questions about NASA's EOS program in the context of global change research. That report, The U.S. Global Change Research Program-An Assessment of the FY 1991 Plans (Committee on Global Change, National Academy Press, Washington, D.C., 1990), observed that: Current policies that govern the use, distribution, and cost of the Landsat and SPOT data make it difficult for the research community to take advantage of this resource. When purchased file:///C|/SSB_old_web/an91ch4.htm (27 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports from the commercial remote sensing industry, the data are generally too expensive for most research purposes. In testimony before the Senate Subcommittee on Science, Technology, and Space in October 1990, Dr. Lennard Fisk, Associate Administrator for the NASA Office of Space Science and Applications, estimated that it would cost over $50 million to purchase enough Landsat Thematic Mapper data to compose one "snapshot" of Earth. Even if access to Landsat data were not significantly inhibited by cost, there would still be a problem in using many of the oldest data. According to a General Accounting Office report, Environmental DataâMajor Effort Is Needed to Improve NOAA's Data Management and Archiving (GAO, Washington, D.C., November 1990), approximately half of the 130,000 Landsat tapes stored at the USGS EROS Data Center are over 10 years old and are deteriorating. The center does not have the hardware to read, process, and maintain over 30,000 tapes of Landsat-1, -2, and -3 data, and some have already deteriorated beyond recovery. SUMMARY CONCLUSIONS AND RECOMMENDATIONS The Landsat system has provided an invaluable environment information resource to our nation and the world. Landsat data have been used in a broad spectrum of basic and applied research. Even more significantly, however, the existing Landsat database and the system's anticipated observations are expected to play an increasingly important role in data-intensive endeavors such as global change research and Geographic Information Systems applications. Finally, there is no existing or planned remote sensing system that currently duplicates or can continue such observations in the event that the Landsat program is discontinued. Not withstanding its notable successes and growing potential, the full capabilities of this unique data-collection system have been consistently underutilized and insufficiently supported, and the future continuity of the program remains in doubt. Although the committee has not analyzed the various options available for managing and operating the Landsat system in the future and makes no recommendations on those issues at this time, we wish to reiterate a number of recommendations made by this and other NRC committees that remain relevant to improving the effectiveness of the Landsat system for basic and applied research. Program Continuity As noted above, the committee places highest priority on maintaining file:///C|/SSB_old_web/an91ch4.htm (28 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports uninterrupted continuity of the Landsat data set. Simply building and flying another spacecraft, however, is not enough to ensure continuity in the observations. First, a single spacecraft in orbit presents the possibility of a single- point failure and an interruption in observations. Most Earth observation spacecraft series that have been designated as "operational"âincluding the current Landsat seriesâmaintain two spacecraft in orbit. This issue should be addressed in any decision to continue the program. Second, the sensors should be operated to obtain global land-surface data sets on a consistent basis. Third, all future sensors must be fully calibrated to enable long-term data intercomparability. Finally, the full value of land remote sensing will be realized only if there is continued research and development to create new sensors and if new generations of researchers are trained to use these data. This latter issue deserves greater attention and coordination among the agencies represented on the Committee on Earth and Environmental Sciences. Access to Data The effective utilization of Landsat data continues to be seriously compromised by their high cost. Although some progress has recently been made in this regard, notably the availability at the cost of reproduction of all Multispectral Scanner data that are at least two years old, the committee agrees with the 1990 NRC report (The U.S. Global Change Research ProgramâAn Assessment of FY 1991 Plans) that: Landsat data are sufficiently important to global change research that means should be found to include them in the EOSDIS, whether by revising the Land Remote Sensing Commercialization Act, if necessary, or by paying (again) for the data. Early inclusion of the Landsat data set in the EOSDIS would be especially useful for the prototype data analysis studies planned under the EOS program. The recommendation is consistent with the "Data Management for Global Change Research Policy Statements," officially released by the Office of Science and Technology Policy on July 2, 1991, which states: Data should be provided at the lowest possible cost to global change researchers in the interest of full and open access to data. This cost should, as a first principle, be no more than the marginal cost of filling a specific user request . . . . The 1990 NRC report cited above also emphasized that: it is in the interest of international research to make all environmental data readily available to the global scientific community . . . . Similarly, U.S. scientists should have access to relevant data in foreign archives, and it is important that other file:///C|/SSB_old_web/an91ch4.htm (29 of 31) [6/18/2004 10:27:04 AM]
Annual Report 1991: Letter Reports nations be encouraged to establish similar data policy assessments. This latter issue takes on increasing significance as the other nations with remote sensing capabilities are placing restrictions on data obtained in their environmental satellite programs. It is particularly important to note that many of the Landsat observations of areas outside North Americaârelevant to global change researchâare received and archived by Landsat ground stations in other countries, and can only be obtained through them. Maintenance of Historical Data As the 1990 GAO report (Environmental DataâMajor Effort Is Needed to Improve NOAA's Data Management and Archiving) pointed out, a significant fraction of the older Landsat data is rapidly deteriorating. Although the USGS has done an outstanding job overall in maintaining voluminous data sets and making them available to the research community, the restoration to the extent possible and proper maintenance of all the Landsat data, whether archived in the United States or abroad, should receive high-priority attention for future research use. The committee believes that a renewed commitment by the government to the continuity of the Landsat program and to its effective applications will benefit the nation, and indeed the world. I would be pleased to discuss these issues with you further at your convenience. Signed by Byron D. Tapley Chairman, Committee on Earth Studies file:///C|/SSB_old_web/an91ch4.htm (30 of 31) [6/18/2004 10:27:04 AM]
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