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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
Research—1990 (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 Applications—Report 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:
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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
Programs—1991, 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
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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.
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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 Handbook—1991:
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.
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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 Programs—1991 (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
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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.
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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 Programs—1991 (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
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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.
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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.
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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
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