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HUMS
EXPLORATION
OF SPACE
A Review of NASA ts
90 Day Study and Alternatives
Committee on Human Exploration of Space
National Research Council
NATIONAL ACADEMY PRESS
Washington, D.C. 1990
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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 dis-
tinguished scholam engaged in scientific and engineering msearch, 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.
The National Academy of Engineering was established in 1964, under the charter of the National
_
Academy or Sciences, as a parallel organization of outstanding engineers. It is autonomous in its
administration and in the selection of its members, sharing with the National Academy of Sciences
the responsibility for advising the federal government. The National Academy of Engineering also
sponsors engineering programs aimed at meeting national needs, encourages education and research,
and recognizes the superior achievemcuts of engineers. Dr. Robert M. White is president of the
National Academy of Engineering.
The Institute of Medicine was established in 1970 by the National Academy of Sciences to
secure the services of eminent members of appropriate professions in the examination of policy
matters pertaining to the health of the public The Institute acts under the responsibility given to the
National Academy 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. Samuel
O. Thier 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 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
govemment, 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.
This study was supported by Contract NASW4003 between the National Academy of Sciences
and the National Aeronautics and Space Administration.
Available from:
Committee on Human Exploration of Space
National Research Council
Room HA 292
2101 Constitution Avenue, NW
Washington, DC 20418
Printed in the United States of America
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COMMITTEE ON HUMAN~EXPLORATION OF SPACE
-Members
H. GUYFORD STEVER, Corporate Director and Science Advisor
(Ret.), Washington, D.C., Chairman
ROBERT H. CANNON, JR, Charles Lee Powell Professor and Chairman,
Department of Aeronautics and Astronautics, Stanford University
JOSEPH G. GAVIN, Senior Management Consultant, Grumman
Corporation, Bethpage, New York
JACK L. KERREBROCK, R.C. Maclaurin Professor of Aeronautics and
Astronautics, Massachusetts Institute of Technology
LOUIS J. LANZERO11I, Distinguished Member of Technical Staff,
Physics Division, AT&T Bell Laboratories, Murray Hill, New Jersey
ELLIOTT C. LEVINTHAL, Associate Dean for Research, Stanford
University
JAMES W. MAR, J. C. Hunsaker Professor of Aerospace Education,
Department of Aeronautics and Astronautics, Massachusetts Institute
of Technology
JOHN H. McELROY, Dean of Engineering, University of Texas at
Arlington
DUANE T. McRUER, President and Technical Director, Systems
Technology, Inc., Hawthorne, California
WILLIAM J. MERRELL, JR., President, Texas A&M University,
Galveston
ROBERT H. MOSER, Vice President for Medical Affairs, The
NutraSweet Company, Deerfield, Illinois
EBERHARDT RECHTIN, Professor of Engineering, University of
Southern California, Los Angeles, California
THOMAS P. STAFFORD, Defense Technologies, Inc., Oklahoma City,
Oklahoma; Stafford, Burke, and Hecker, Alexandria, Virginia
LAURENCE R. YOUNG, Professor of Aeronautics and Astronautics and
Director, Man-Vehicle Laboratory, Massachusetts Institute of
Technology
Advisors to the Committee
JAY BOUDREAU, Ballena Corporation, Los Alamos, New Mexico
PETER DEWS, Harvard Medical School, Boston, Massachusetts
ANDREA K. DUPREE, Center for Astrophysics, Cambridge,
Massachusetts
JONATHAN LUNINE, University of Arizona, Tucson, Arizona
. . .
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THOMAS ~ POTEMRA, Johns Hopkins University, Laurel, Maryland
THOMAS SHERIDAN, Massachusetts Institute of Technology
Staff
JOANN C. CLAYTON, Study Director
CHRISTINA ~ WEINLAND, Project Secretary
ANNA L. FARRAR, Administrative Coordinator
1V
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In Memoriam
General Samuel C. Phillips, who had agreed to serve on the Committee
on Human Exploration of Space and who had begun preparatory work for
the study, died on January 31, 1990. He had a long and distinguished career
that included directing the Apollo program from 1964 through the lunar
landing in 1969, commanding the US Air Force Space and Missile Systems
Organization, directing the National Security Agency, and heading the Air
Force Systems Command. General Phillips later served as a Vice President
for 1'RW. He performed many analyses of critical US space issues, and only
recently was a valued member of a National Academy of Sciences/National
Academy of Engineering study of US space policy. General Phillips' death
is a great loss to the nation and to his colleagues who worked with him
through the years.
v
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Acknowledgments
The committee wishes to thank the many individuals from industry,
academia, and federal agencies and laboratories who took the time either
to meet with the committee or to make their views available in other ways.
NASA Administrator Richard Duly, his associate administrators and staff,
along with National Space Council Executive Secretary Mark Albrecht and
his staff, were very frank and forthcoming with information concerning the
President's human space exploration initiative.
In addition, the following individuals presented their ideas and tech-
nical concepts to the committee: Lowell Wood and his associates from the
Lawrence Livermore National Laboratory, who briefed us on The Great
Exploration; General Richard C. Henry of Brown & Root, who discussed
the Workhorse Launch System; Maxwell W. Hunter, who made a presenta-
tion on the SSX, a single-stage-to~rbit launch system; Peter Wilhelm of the
Naval Center for Space Technology, who explained the SEALAR concept,
involving launching recoverable vehicles at sea; Michael D. Gri~n, Deputy
for Technology of the Strategic Defense Organization, who discussed project
management techniques; and Lt. Colonel Roger Lenard, who described a
nuclear propulsion concept. A full list of invitied presenters and guests is
contained in Appendix B.
Thanks are in order as well to the staffs of the National Research
Council (NRC) Space Studies Board and the Aeronautics and Space En-
gineering Board for their help and cooperation in putting together the
. .
V11
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· ~ .
VU1
ACRNOVVLEDGMEN7S
study. Last, we would especially like to thank the study's Executive Direc-
tor JoAnn Clayton for her thoughtful guidance at every stage and NRC
Assistant Executive Officer for Special Projects Myron F. Uman for his wise
counsel and constructive reviews of the draft report.
H. Guyford Stever, Chairman,
Committee on Human Exploration of Space
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Summary
President George Bush on July 20, 1989, announced a US commitment
for humans to return to the Moon and to journey to Mars; the Vice Presi-
dent in his capacity as Chairman of the National Space Council (NSC) was
charged with making specific recommendations about how the President's
initiative could best be achieved. The National Aeronautics and Space Ad-
ministration (NASA) then prepared a document, based on earlier NASA
analyses, to aid in the decision-making process. Subsequently, the Vice
President requested that the National Research Council (NRC) assess the
scope and content of the NASA document as well as alternative approaches
and various technology issues. The Vice President presented the NRC with
a challenging set of questions that resulted in this report.
In examining the NASA Report of the 90-D``y Study on Human Ex-
ploration of the Moon and Mars and alternative concepts, the committee
concluded that the appropriate framework in which to consider alternative
approaches to meeting the President's initiative has at least four compo-
nents. The committee's major findings and conclusions follow, presented
in that framework.
MISSION CONCEPTS
Questions arise about the appropriate pace for the President's ini-
tiative; the scope of initial human exploration missions; and the level of
long-term support that will be required for what could be an unprecedent-
edly long commitment to a national space goal. Development of policy,
1X
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x
SUMMARY
advanced technologies, and mission concepts will probably be a continu-
ing and iterative process. However, there is a need for guidance at an
early date regarding the scope and pace of the early stages of the Human
Exploration Initiative (HEI).
· As directed by the President, the space station is an integral first
step in the HEI, but its present design may not meet all of the requirements
for the HEI.
· The mission concepts in the NASA 90-Day Study prudently build on
proven concepts and methodical research, development, and demonstration
of new technology. The concepts are comprehensive and robust, implying
relatively low risk.
The Great Exploration, a concept developed by the Special Projects
Office of the Lawrence Livermore National Laboratory, proposes to use
available terrestrial equipment, accelerated administrative and procurement
procedures, and a potentially feasible technology (inflatable modules) in an
aggressive approach to reach Mars at the earliest possible time, but entails
relatively high risk. The concept contains technical ideas Hat should be
pursued, but the committee believes it underestimates the many practical
and difficult engineering and operational challenges involved.
· It appears likely that the eventual choice of mission architecture
will incorporate the ideas from a variety of concepts, some that now exist
and others that will arise in the future. One concept, for example, would
place the permanent human habitat in orbit, rather than on the surface
of Mars. The variety of concepts should be regarded as a "menu" of
opportunities.
lIUMANS IN SPACE
Significant unanswered scientific questions exist concerning the fea-
sibility of long-duration human spaceflight in a low-gravity environment.
While it has been demonstrated that the human body adjusts remarkably
well to the absence of gravity for short-duration flights, it has not been
demonstrated that after long-duration spaceflight individuals can readjust
rapidly to gravity without serious physiological consequences. The capa-
bility to send humans into space, maintain them in a physical condition
that permits them to work productively, and return them to Earth in good
health is central to the HEI.
· A program of scientific research on the effects of microgravity on
human performance and welfare is critical for determining the mission
architecture for the HEI.
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SUMMARY
X1
· Development of technology for artificial gravity and countermea-
sures to mitigate zero-g exposure should proceed in parallel with studies of
the physiological effects of microgravity.
· An emphasis on advanced human/machine systems can enhance
the productivity of humans in space and increase their safetr.
TECHNOLOGY DEVELOPMENT
Strategies are needed to develop and employ new technologies that
will enable more rapid or cost-effective access to and habitation in space.
Developing these strategies implies making trade-offs among alternative
approaches. An important factor in these decisions is the level of human
and technical risk that is acceptable. While major aerospace undertakings
usually entail risk;, recognizing them early in the planning stages of a major
initiative may help identify choices that offer opportunities to manage
the risks. A balanced technology development program with emphasis
on critical long-term technologies can help to reduce risks and provide
important options for the future.
Second to the need for scientific research and technology develop-
ment to support humans in space is the need to advance national space
transportation capabilities.
.
A new generation of heavy lift launch vehicles is needed to transport
massive cargoes to low Earth orbit (LEO).
~ transport humans to space, the nation must rely on the space
shuttle for at least 10 years, and it is essential that the existing shuttle
fleet be maintained in a fully operable condition. A new vehicle eventually
will be required to transport humans and other precious cargo to LEO,
emphasizing high reliability, robustness, and efficient ground operations.
· Nuclear rocket propulsion could make an important contribution
to the HEI if it proves feasible and safe and can gain public acceptance.
· 1b meet the heavy demands for power on the Moon or Mars,
nuclear electric power eventually will be essential.
SCIENCE GOALS
Another set of considerations concerns the expansion of knowledge.
While the cardinal goals for the HEI may be related to leadership im-
peratives and to revitalizing the national research and development effort,
important information can be gained about ourselves and our planet, about
ongoing and past physical and biological processes, and about the history
of the universe.
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~ .
X11
SUMMARY
· Scientific research required to enable the initiative Includes robotic
precursor missions to learn more about the Moon and Mars as well as
critical studies in the life sciences.
Other research opportunities can be enabled by the HEI, for ex-
ample, astronomical studies from a lunar base and geological studies of the
Moon and Mars.
Research that may become possible because of the HEI should be
evaluated in the context of research strategies for the respective scientific
disciplines, and with consideration of alternative ways of conducting the
research. This analysis should be based on detailed scientific discussions
and strategy development.
· Before defining scientific research for a lunar base, evaluations
are needed on the effects of an inhabited lunar environment on scientific
objectives and on instrumentation.
ADDITIONAL CONSIDERATIONS
The committee assumed that, independent of a program for human
exploration of space, a vigorous base of civil space programs will exist,
including astronomical research, solar and space physics, unmanned plan-
etary exploration, and Earth remote sensing, supported in the near term
by both expendable launch vehicles and by the space shuttle. In addition,
technology will be developed, operational experience gained, and valuable
scientific information obtained by the space programs of Europe, the USSR,
and Japan, as well as by our own military space programs.
The climate for international cooperation is changing and is likely to
continue to change. A detailed assessment is needed of the opportunities
for international cooperation that may be available and the means to
overcome technical and institutional barriers. It would be prudent to
remain alert to future opportunities that may arise. At the same time, care
must be taken that any enabling agreements are supported at the highest
possible levels in the participating governments, with as much breadth as
feasible, and that detailed technical agreements are not made final before
all parties understand and agree on the requirements for the HEI or
missions associated with it.
Finally, the nation is at a very early stage in the development of
an HEI. None of the analyses to date the NASA 90-Day Study, The
Great Exploration, or, indeed, this report—should be regarded as providing
anything other than a framework for further discussion, innovation, and
debate. The HEI is an ambitious undertaking that requires development
and implementation of new technology. Accurate cost estimates are only
practical in circumstances where experience with the technology exists.
Currently, the technologies and the HEI mission architectures are unknown.
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SUMMARY
xiii
While the nation has experience with estimating costs of some aspects of
HEI, derived from experience with the costs of past space systems, at this
time mission cost estimates should only be taken as suggesting the rough
order of magnitude of the eventual costs.
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Contents
INTRODUCTION
Background, 1
Procedure, 2
Approach, 3
I. ALTERNATIVE MISSION CONCEPTS
The Space Station as a First Step, 5
The NASA Report of the 90-Day Study on Human
Exploration of the Moon and Mars, 6
The Great Exploration, 7
Other Architectures for the Human Exploration Initiative, 9
II. SPACE TRANSPORTATION: LAUNCH SYSTEMS,
PROPULSION, AND POWER
Human Transportation to and from Orbit, 12
Unmanned Launch Systems, 12
Nuclear Thermal Propulsion, 14
Nuclear Electric Power, 15
III. OTHER CRITICAL TECHNOLOGIES FOR THE
HUMAN EXPLORATION INITIATIVE
The NASA 90-Day Study, 17
1
s
11
17
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xvi
Artificial Gravity, 18
Advanced Human/Machine Systems, 19
IV. SPACE SCIENCE AND THE HUMAN EXPLORATION
INITIATIVE
Scientific Knowledge as a Prerequisite for Human Exploration, 22
Life Sciences, 22
Physical Sciences, 24
Research Opportunities to be Derived from Prolonged Human
Space Missions, 25
V. NONTECHNICAL CONSIDERATIONS
Infrastructure Considerations, 27
The Responsible Federal Entity, 27
The NASA Infrastructure, 28
International Considerations, 29
Cost for the Human Exploration Initiative, 30
VI. SUMMARY RESPONSES TO QUESTIONS POSED BY
THE VICE PRESIDENT
Scope of the Report of the NASA 90-Day Study, 33
Content of the Report of the 90-Day Study, 35
BIOGRAPHICAL SKETCHES OF COMMI l lE;E MEMBERS
BIBLIOGRAPHY
ACRONYMS, ABBREVIATIONS, AND TECHNICAL TERMS
APPENDIXES
A December 4, 1989, Letter from Vice President Dan Quayle
to Dr. Frank Press and Dr. Press' Response
B List of Participants
C Excerpts from the President's July 20, 1989, Speech and
the November 2, 1989, National Space Policy
CONTENTS
21
27
33
39
45
49
53
58
61