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Toward a Microgravity Research Strategy
Toward a Microgravity
Research Strategy
NOTICE
MEMBERSHIP
SUMMARY
CHAPTER 1
CHAPTER 2
CHAPTER 3
Committee on Microgravity Research
CHAPTER 4
Space Studies Board
APPENDIX A
Commission on Physical Sciences,
APPENDIX B
Mathematics, and Applications
APPENDIX C
APPENDIX D National Research Council
APPENDIX E
APPENDIX F
NOTICE
MEMBERSHIP
SUMMARY AND RECOMMENDATIONS
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Toward a Microgravity Research Strategy
Introduction
Nature of the Field
Status of the Field
The Conduct of Microgravity Research
Conclusions and Recommendations
References
1. OVERVIEW OF MICROGRAVITY RESEARCH
Examples of Microgravity Experiments
Reference
2. STATUS OF THE FIELD
References
3. THE CONDUCT OF MICROGRAVITY RESEARCH
Instrumentation
Manned Versus Robotic Interaction
Range of Microgravity Facilities
Microgravity Research Outside the United States
Commercial Programs
The Research and Analysis Program
References
4. TOWARD THE DEVELOPMENT OF A RESEARCH STRATEGY
APPENDIXES
A. Biological Sciences
B. Combustion Science
C. Electronic Materials
D. Fluids, Interfaces, and Transport
E. Glasses and Ceramics
F. Metals and Alloys
NATIONAL ACADEMY PRESS, 1992
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Toward a Microgravity Research Strategy (Notice)
Toward a Microgravity Research Strategy
NOTICE: The project that is the subject of this report was approved by the
Governing Board of the National Research Council, whose members are drawn
from the councils of the National Academy of Sciences, the National Academy of
Engineering, and the Institute of Medicine. The members of the committee
responsible for the report were chosen for their special competences and with
regard for appropriate balance.
This report has been reviewed by a group other than the authors
according to procedures approved by a Report Review Committee consisting of
members of the National Academy of Sciences, the National Academy of
Engineering, and the Institute of Medicine.
The National Academy of Sciences is a private, nonprofit, self-
perpetuating society of distinguished scholars engaged in scientific and
engineering research, dedicated to the furtherance of science and technology
and to their use for the general welfare. Upon the authority of the charter granted
to it by the Congress in 1863, the Academy has a mandate that requires it to
advise the federal government on scientific and technical matters. Dr. Frank
Press is president of the National Academy of Sciences.
REPORT MENU The National Academy of Engineering was established in 1964, under the
NOTICE charter of the National Academy of Sciences, as a parallel organization of
MEMBERSHIP outstanding engineers. It is autonomous in its administration and in the selection
SUMMARY of its members, sharing with the National Academy of Sciences the responsibility
CHAPTER 1
for advising the federal government. The National Academy of Engineering also
CHAPTER 2
sponsors engineering programs aimed at meeting national needs, encourages
CHAPTER 3
education and research, and recognizes the superior achievements of engineers.
CHAPTER 4
Dr. Robert M. White is president of the National Academy of Engineering.
APPENDIX A
APPENDIX B
The Institute of Medicine was established in 1970 by the National
APPENDIX C
Academy of Sciences to secure the services of eminent members of appropriate
APPENDIX D
professions in the examination of policy matters pertaining to the health of the
APPENDIX E
public. The Institute acts under the responsibility given to the National Academy
APPENDIX F
of Sciences by its congressional charter to be an adviser to the federal
government and, upon its own initiative, to identify issues of medical care,
research, and education. Dr. Kenneth I. Shine is president of the Institute of
Medicine.
The National Research Council was organized by the National Academy
of Sciences in 1916 to associate the broad community of science and technology
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Toward a Microgravity Research Strategy (Notice)
with the Academy's purposes of furthering knowledge and advising the federal
government. Functioning in accordance with general policies determined by the
Academy, the Council has become the principal operating agency of both the
National Academy of Sciences and the National Academy of Engineering in
providing services to the government, the public, and the scientific and
engineering communities. The Council is administered jointly by both Academies
and the Institute of Medicine. Dr. Frank Press and Dr. Robert M. White are
chairman and vice chairman, respectively, of the National Research Council.
Support for this project was provided by Contract NASW 4627 between
the National Academy of Sciences and the National Aeronautics and Space
Administration.
Copies of this report are available from
Space Studies Board
National Research Council
2101 Constitution Avenue, N.W.
Washington, D.C. 20418
Printed in the United States of America
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Toward a Microgravity Research Strategy (Membership)
Toward a Microgravity Research Strategy
Membership
COMMITTEE ON MICROGRAVITY RESEARCH
ROBERT F. SEKERKA,* Carnegie Mellon University, Chairman
ROBERT A. BROWN, Massachusetts Institute of Technology
FRANKLIN D. LEMKEY, United Technologies Research Center
WILLIAM A. SIRIGNANO, University of California, Irvine
THOMAS A. STEITZ, The Howard Hughes Medical Institute
Space Studies Board Member (July 1989 to June 1991)
JOHN R. CARRUTHERS
Space Studies Board Staff
REPORT MENU JOYCE M. PURCELL, Executive Secretary
NOTICE MELANIE M. GREEN, Administrative Secretary
MEMBERSHIP CARMELA J. CHAMBERLAIN, Administrative Secretary
SUMMARY
CHAPTER 1
CHAPTER 2
_____________________
CHAPTER 3
*Member, Space Studies Board, July 1989 to June 1992.
CHAPTER 4
APPENDIX A
APPENDIX B
APPENDIX C
APPENDIX D SPACE STUDIES BOARD
APPENDIX E
APPENDIX F
LOUIS J. LANZEROTTI, AT&T Bell Laboratories, Chairman
JOSEPH A. BURNS, Cornell University
ANDREA K. DUPREE, Harvard-Smithsonian Center for Astrophysics
JOHN A. DUTTON, Pennsylvania State University
LARRY W. ESPOSITO, University of Colorado, Boulder
JAMES P. FERRIS, Rensselaer Polytechnic Institute
HERBERT FRIEDMAN, Naval Research Laboratory (retired)
RICHARD L. GARWIN, IBM T.J. Watson Research Center
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Toward a Microgravity Research Strategy (Membership)
RICCARDO GIACCONI, Space Telescope Science Institute
NOEL W. HINNERS, Martin Marietta Civil Space and Communications Company
JAMES R. HOUCK, Cornell University
DAVID A. LANDGREBE, Purdue University
RICHARD S. LINDZEN, Massachusetts Institute of Technology
JOHN H. McELROY, University of Texas at Arlington
WILLIAM J. MERRELL, JR., Texas A&M University
RICHARD K. MOORE, University of Kansas
ROBERT H. MOSER, The NutraSweet Company
NORMAN F. NESS, University of Delaware
MARCIA NEUGEBAUER, Jet Propulsion Laboratory
MARK SETTLE, ARCO Oil and Gas Company
WILLIAM A. SIRIGNANO, University of California, Irvine
FRED TUREK, Northwestern University
ARTHUR B.C. WALKER, Stanford University
MARC S. ALLEN, Director
COMMISSION ON PHYSICAL SCIENCES,
MATHEMATICS, AND APPLICATIONS
NORMAN HACKERMAN, Robert A. Welch Foundation, Chairman
PETER J. BICKEL, University of California at Berkeley
GEORGE F. CARRIER, Harvard University
GEORGE W. CLARK, Massachusetts Institute of Technology
DEAN E. EASTMAN, IBM T.J. Watson Research Center
MARYE ANNE FOX, University of Texas
PHILLIP A. GRIFFITHS, Institute for Advanced Studies
NEAL F. LANE, Rice University
ROBERT W. LUCKY, AT&T Bell Laboratories
CLAIRE E. MAX, Lawrence Livermore Laboratory
CHRISTOPHER F. McKEE, University of California at Berkeley
JAMES W. MITCHELL, AT&T Bell Laboratories
RICHARD S. NICHOLSON, American Association for the Advancement of
Science
ALAN SCHRIESHEIM, Argonne National Laboratory
KENNETH G. WILSON, Ohio State University
NORMAN METZGER, Executive Director
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Toward a Microgravity Research Strategy (Summary and Recommendations)
Toward a Microgravity Research Strategy
Summary and Recommendations
INTRODUCTION
As part of a self-assessment and subsequent reorganization in 1989, the
Space Studies Board (SSB) created a new standing committee—the Committee
on Microgravity Research (CMGR). The formation of the committee was due, in
part, to the dissolution of the National Research Council's (NRC's) Space
Applications Board, which, until 1988, held the NRC's advisory responsibility for
microgravity issues.
Over the course of the past 20 years, the Space Studies Board has,
through its standing discipline committees, developed and published a series of
research strategies for each of the major space research disciplines. These
strategies are meant to serve as guides for the National Aeronautics and Space
Administration (NASA) in planning its space research program. As one of its
charges, the CMGR was asked by the SSB ". . . to conduct a study on the
REPORT MENU maturity and state of readiness of the field for the development of a
NOTICE comprehensive long-range research strategy."
MEMBERSHIP
SUMMARY
In this report to the SSB, the CMGR finds that the various subdisciplines
CHAPTER 1
of the field are heterogeneous in both their nature and state of maturity. This is
CHAPTER 2
reflected in Appendixes A to F, which briefly discuss the status,
CHAPTER 3
accomplishments, and prospects and opportunities for each microgravity
CHAPTER 4
research subdiscipline. Notwithstanding this inherent heterogeneity, the
APPENDIX A
CMGR concludes that the field as a whole would benefit from the
APPENDIX B
formulation of a long-range research strategy and that such a strategy
APPENDIX C
should be developed as soon as possible.
APPENDIX D
APPENDIX E
APPENDIX F
NATURE OF THE FIELD
Microgravity research encompasses scientific investigation conducted in a
gravitational field (or equivalent acceleration with respect to an inertial frame) that
is a small fraction of the gravitational acceleration on Earth. The role of gravity in
physical phenomena is uniquely important in a limited set of circumstances,
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Toward a Microgravity Research Strategy (Summary and Recommendations)
including the following:
1. As a driving force for convection in fluids,
2. As a driving force for phase separation,
3. As a force that helps to determine the free surface morphology of
fluids,
4. Near a critical point,
5. In the presence of very weak binding forces,
6. In the presence of very large masses or for very long times, and
7. In structural members or over large distances.
To date, most microgravity experiments have been focused on exploring
the first two roles above. These experiments have included studies of crystal
growth in fluids, fundamental phenomena in crystal growth, convection
phenomena, measurement of the transport properties of fluids, combustion
phenomena, fire safety aboard spacecraft, and immiscible alloys and multiphase
solids.
STATUS OF THE FIELD
Between 1989 and 1991, the CMGR reviewed the status of microgravity
research, the activities of NASA's Microgravity Science and Applications Division,
and previous studies such as Materials Processing in Space,1 Microgravity
Science and Applications,2 Review of Microgravity Science and Applications
Flight Programs—January-March 1987,3 and Fluid Sciences and Materials
Science in Space—a European Perspective.4 Based on this review, the CMGR
reached the following conclusions.
Fluids, interfaces, and transport; metals and alloys; and combustion
science are more developed than the other subdisciplines of the field. The
biological sciences category shows promise in the area of protein crystal growth,
but little in other aspects such as electrophoresis. Current research holds out little
hope for explaining why protein crystals grow differently in space or how to
exploit the differences. Excellent-although only a few experiments are planned in
the subdiscipline of fundamental processes. Recommendations for future
experiments in this direction are more likely to be derived from unsolicited
proposals than from Announcements of Opportunity (AOs) issued by NASA.
Research in the area of electronic materials has concentrated on bulk materials
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thus far. There is some indication that these experiments will produce information
of scientific importance. However, concentration on bulk materials is contrary to
the mainstream of the field, which emphasizes research on the properties of thin
films deposited on substrates rather than research on electronic properties.
Current research on the qualities of bulk crystals (when used as substrates)
suggests that such crystals may hold some practical value. The subdiscipline of
glasses and ceramics is relatively undeveloped at present; some research in this
area overlaps with research in metals and alloys.
It should be recognized that microgravity research is a relatively new and
laboratory-intensive field that requires frequent access to space. So far, progress
has been limited considerably by the paucity of flight opportunities.
THE CONDUCT OF MICROGRAVITY RESEARCH
Microgravity research must be performed in an environment far from
Earth and, therefore, is largely inaccessible. In addition, it is extremely expensive,
both in terms of the initial investment and in operating costs, particularly when
humans are involved.
The conduct tit microgravity research requires the development of
scientific equipment that is capable of withstanding the stresses of launch and
reentry and of functioning reliably and safely in space. The interaction of users
with this equipment is quite different from their interaction with other space
instruments. Often, the users of microgravity equipment must change
experimental parameters from run to run of an experiment. A more efficient
approach to designing and building equipment would be to provide
instrumentation that is specific to the experiment or class of experiments and that
is designed and built in close cooperation with the principal investigator(s). This
would be a departure from current practice, in which equipment is developed for
a broad population of users.
Microgravity experiments can be carried out in a variety of modes,
ranging from continuous human intervention to full automation. An optimum
microgravity research program would use a mixture of modes, depending on the
set of experiments to be performed, the state of the technology, and cost-
effectiveness. Some microgravity experiments require a manned, space-based
laboratory (such as a space station), while others can be done well or better, and
at a much lower cost, by other means such as in satellites, rockets, and drop
towers.
A wide range of facilities—from ground-based drop tubes to the complex
facilities of the Shuttle-based Spacelab—can provide microgravity conditions. An
experimenter's choice of facility should be based on specific research needs as
well as cost.
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CONCLUSIONS AND RECOMMENDATIONS
Development of a Research Strategy
The Committee on Microgravity Research recommends that a long-
term research strategy, such as that developed by the Space Studies
Board's other discipline committees, be developed for microgravity
science. In addition to defining the overall goals of the microgravity science field
and summarizing the current knowledge of its subdisciplines, this strategy should
identify the fundamental questions that need to be addressed and the scientific
community's ability to address them. Consideration should be given to all modes
of doing this type of research, with attention to maximizing experimental return
and minimizing cost. The primary objectives defined should be ranked in order of
priority and should be accompanied by the criteria used to determine their
priority. Critical components necessary to support a successful microgravity
research program should be described and appropriate measurement indicators
developed.
Microgravity Research Versus Materials Processing
It should be recognized that, to date, no examples have been found of
materials that are worthy of manufacture in space. Unless and until such
examples are found, space manufacturing of products to be used on earth
should be deemphasized as a reason for undertaking microgravity
research. The descriptor "materials processing" is misleading and should be
eliminated. The CMGR recommends that "microgravity research" be used
instead. The main rationale for the microgravity research program should be to
improve our fundamental scientific and technological knowledge base,
particularly in areas that are likely to lead to improvements in processing and
manufacturing on Earth. A secondary rationale should be to develop the
technologies for handling materials in space and possibly for processing
materials to be used in space.
Subdivisions for Microgravity Research
Microgravity research encompasses a wide range of subdisciplines.
NASA's Microgravity Science and Applications Division and its advisory groups
are currently divided into seven "disciplines": biological sciences; combustion
science; electronic materials; fluids, interfaces, and transport; fundamental
processes; glasses and ceramics; and metals and alloys.
After careful consideration, the Committee on Microgravity Research as
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concluded that the current subdivisions of microgravity science should be
revised. The CMGR recommends that microgravity research be reorganized
into six categories that reflect future opportunities more realistically,
including:
Biological science and technology,
Combustion,
Fluid science,
Fundamental phenomena,
Materials, and
Processing science and technology.
Conduct and Support of
the Research and Analysis Program
A thorough program of ground-based research should precede and follow
every microgravity flight. When exemplary materials are produced in microgravity,
attempts should be made to replicate them using ground-based research. In
addition, much more effort should be made to model phenomena suggested by
microgravity observations.
Research projects include both focused opportunities advertised through
AOs issued by NASA and unsolicited proposals submitted to NASA. The
research and analysis program in NASA's Microgravity Science and Applications
Division consists of the ground-based research needed to provide the context of
knowledge from which the flight program originates as well as the infrastructure
required to analyze microgravity experiments in a broader context. If microgravity
research is to develop into a mature field, the current research program should
be reconstituted and refocused in order to improve its health and to provide new
opportunities. The CMGR recommends that NASA apply a set of value
criteria and measurement indicators to define the research and analysis
program more clearly. These value criteria and indicators should be compared
with other areas of physical and chemical sciences to calibrate funding levels with
research output over a reasonable period of time (such as three years).
If research of higher quality and wider diversity is to be incorporated into
the microgravity research program, it is imperative that the research and analysis
budget be a larger fraction of the total microgravity budget. The CMGR
recommends that the funding level for research and analysis in
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microgravity science be established as a fixed percentage of the total
program of NASA's Microgravity Science and Applications Division in order
to build a strong scientific base for future experiments.
Content of the Program and Facilities
Materials employed in microgravity environments should be characterized
thoroughly before and after flight. The thermophysical data needed to interpret
experiments should be measured as a part of the program if they arc not
available in the literature. Contemporary interest in electronic materials focuses
on thin films. Bulk electronic materials are of secondary importance and should
be studied in microgravity only to the extent that they will yield fundamental
knowledge about processing.
When promising results have been obtained, experiments should be
repeated to examine their reproducibility; in particular, experiments should be
designed and conducted to learn why microgravity makes a measurable
difference. Experiments should be analyzed and classified according to their
minimum facility requirements so that they can be carried out in the most cost-
effective manner. The committee recommends that a concerted effort also be
made to classify experiments according to their minimum needs in order
that the most cost-effective access to reduced gravity will be used.
Equipment to accomplish specific experiments should be designed and built in
close cooperation with the principal investigator(s). The acceleration vector
environment must be measured accurately, locally, frequently, and synchronously
with every experiment. These data should be provided to the principal
investigators immediately. Whenever exemplary materials are produced in
microgravity, considerable effort should be exerted to replicate them in ground-
based research.
Commercial Programs
In addition to the activities financed by NASA's Microgravity Science and
Applications Division, NASA funds commercial microgravity research through its
Office of Commercial Programs. This office provides incentives for space
experiments and, in cooperation with industry, has established centers for the
commercial development of space (CODS) at several universities. Started in
1986, these centers were given five years in which to become independent
through increased industrial funding. The CMGR recommends that a thorough
technical review of the centers for commercial development of space be
conducted to determine the quality of their activities and to ascertain to
what degree their original mission has been accomplished.
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REFERENCES
1. Committee on Scientific and Technological Aspects of Materials
Processing in Space, Space Applications Board. 1978. Materials Processing in
Space. National Academy of Sciences, Washington, D.C.
2. Solid State Sciences Committee, Board on Physics and Astronomy.
1986. Microgravity Science and Applications: Report on a Workshop. National
Academy Press, Washington, D.C.
3. Review Committee, J. Robert Shrieffer, chairman. 1987. Review of
Microgravity Science and Applications Flight Programs—January-March 1987.
Universities Space Research Association, Washington, D.C.
4. European Space Agency. 1987. Fluid Sciences and Materials Science
in Space—a European Perspective. Springer-Verlag.
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