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 committees responsible for the report were chosen for their special competences and with regard for appropriate balance.
Support for this project was provided by Contract NASW 96013 between the National Academy of Sciences and the National Aeronautics and Space Administration. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the sponsor.
Cover: Ground track of ISS orbits superposed on a globe along with polar cap areas (shown in yellow), where multimega-electron volt solar energetic particles penetrated to low altitudes during an SPE in November 1997. (Image courtesy of R.A. Leske, R.A. Mewaldt, E.C. Stone, and T.T. von Rosenvinge, “Geomagnetic Cutoff Variations During Solar Energetic Particle Events—Implications for the Space Station,” Proceedings of the 25th International Cosmic Ray Conference, 2, Space Research Unit, Department of Physics, Potchefstroom University for Christian Higher Education, South Africa, 1997, p. 381.)
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THE NATIONAL ACADEMIES
National Academy of Sciences
National Academy of Engineering
Institute of Medicine
National Research Council
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. Bruce M. Alberts is president of the National Academy of Sciences.
The National Academy of Engineering was established in 1964, under the charter of the National Academy of 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 achievements of engineers. Dr. William A. Wulf 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. 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 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. Bruce M. Alberts and Dr. William A. Wulf are chairman and vice chairman, respectively, of the National Research Council.
COMMITTEE ON SOLAR AND SPACE PHYSICS
GEORGE L. SISCOE,
Boston University,
Chair
CHARLES W. CARLSON,
University of California, Berkeley
ROBERT L. CAROVILLANO,
Boston College
TAMAS I. GOMBOSI,
University of Michigan
RAYMOND A. GREENWALD,
Applied Physics Laboratory
JUDITH T. KARPEN,
Naval Research Laboratory
GLENN M. MASON,
University of Maryland
MARGARET A. SHEA,
Air Force Research Laboratory
KEITH T. STRONG,
Lockheed Palo Alto Research Center
RICHARD A. WOLF,
Rice University
ARTHUR CHARO, Senior Program Officer
RONALD TURNER, Consultant
CARMELA J. CHAMBERLAIN, Senior Project Assistant (through March 1999)
THERESA M. FISHER, Senior Project Assistant (from April 1999)
COMMITTEE ON SOLAR-TERRESTRIAL RESEARCH
MICHAEL C. KELLEY,
Cornell University,
Chair
MAURA E. HAGEN,
National Center for Atmospheric Research
MARY K. HUDSON,
Dartmouth College
NORMAN F. NESS,
Bartol Research Institute
THOMAS F. TASCIONE,
Sterling Software
ELBERT (JOE) FRIDAY, JR., Director,
Board on Atmospheric Sciences and Climate
TENECIA A. BROWN, Senior Project Assistant
SPACE STUDIES BOARD
CLAUDE R. CANIZARES,
Massachusetts Institute of Technology,
Chair
MARK R. ABBOTT,
Oregon State University
FRAN BAGENAL,
University of Colorado
DANIEL N. BAKER,
University of Colorado
ROBERT E. CLELAND,
University of Washington
GERARD W. ELVERUM, JR.,
TRW Space and Technology Group*
MARILYN L. FOGEL,
Carnegie Institution of Washington
BILL GREEN,
Former Member, U.S. House of Representatives
JOHN H. HOPPS, JR.,
Morehouse College
CHRIS J. JOHANNSEN,
Purdue University
ANDREW H. KNOLL,
Harvard University*
RICHARD G. KRON,
University of Chicago
JONATHAN I. LUNINE,
University of Arizona
ROBERTA BALSTAD MILLER,
CIESIN-Columbia University
GARY J. OLSEN,
University of Illinois, Urbana-Champaign
MARY JANE OSBORN,
University of Connecticut Health Center
GEORGE A. PAULIKAS,
The Aerospace Corporation
JOYCE E. PENNER,
University of Michigan
THOMAS A. PRINCE,
California Institute of Technology
PEDRO L. RUSTAN, JR.,
Ellipso, Inc.
GEORGE L. SISCOE,
Boston University
EUGENE B. SKOLNIKOFF,
Massachusetts Institute of Technology
MITCHELL SOGIN,
Marine Biological Laboratory
NORMAN E. THAGARD,
Florida State University
ALAN M. TITLE,
Lockheed Martin Advanced Technology Center
RAYMOND VISKANTA,
Purdue University
PETER VOORHEES,
Northwestern University
JOHN A. WOOD,
Harvard-Smithsonian Center for Astrophysics
JOSEPH K. ALEXANDER, Director
BOARD ON ATMOSPHERIC SCIENCES AND CLIMATE
ERIC J. BARRON,
Pennsylvania State University,
Co-chair
JAMES R. MAHONEY,
International Technology Corporation,
Co-chair
SUSAN K. AVERY,
University of Colorado
LANCE F. BOSART,
State University of New York at Albany
MARVIN A. GELLER,
State University of New York at Stony Brook
DONALD M. HUNTEN,
University of Arizona*
JOHN IMBRIE,
International Technology Corporation*
CHARLES E. KOLB,
Aerodyne Research, Inc.
THOMAS J. LENNON, Brig. Gen. USAF (ret.),
WSI Corp.*
ROGER A. PIELKE, JR.,
National Center for Atmospheric Research
ROBERT T. RYAN,
WRC-TV
MARK R. SCHOEBERL,
NASA Goddard Space Flight Center
JOANNE SIMPSON,
NASA Goddard Space Flight Center
NIEN DAK SZE,
Atmospheric and Environmental Research, Inc.
ROBERT WELLER,
Woods Hole Oceanographic Institution
ERIC F. WOOD,
Princeton University
ELBERT (JOE) FRIDAY, JR., Director
COMMISSION ON PHYSICAL SCIENCES, MATHEMATICS, AND APPLICATIONS
PETER M. BANKS,
Veridian ERIM International, Inc.,
Co-chair
W. CARL LINEBERGER,
University of Colorado,
Co-chair
WILLIAM F. BALLHAUS, JR.,
Lockheed Martin Corp.
SHIRLEY CHIANG,
University of California at Davis
MARSHALL H. COHEN,
California Institute of Technology
RONALD G. DOUGLAS,
Texas A&M University
SAMUEL H. FULLER,
Analog Devices, Inc.
JERRY P. GOLLUB,
Haverford College
MICHAEL F. GOODCHILD,
University of California at Santa Barbara
MARTHA P. HAYNES,
Cornell University
WESLEY T. HUNTRESS, JR.,
Carnegie Institution
CAROL M. JANTZEN,
Westinghouse Savannah River Company
PAUL G. KAMINSKI,
Technovation, Inc.
KENNETH H. KELLER,
University of Minnesota
JOHN R. KREICK,
Sanders, a Lockheed Martin Company (ret.)
MARSHA I. LESTER,
University of Pennsylvania
DUSA M. McDUFF,
State University of New York at Stony Brook
JANET L. NORWOOD, U.S. Commissioner of Labor Statistics (ret.)
M. ELISABETH PATÉ-CORNELL,
Stanford University
NICHOLAS P. SAMIOS,
Brookhaven National Laboratory
ROBERT J. SPINRAD,
Xerox PARC (ret.)
NORMAN METZGER, Executive Director (through July 1999)
MYRON F. UMAN, Acting Executive Director (from August 1999)
COMMISSION ON GEOSCIENCES, ENVIRONMENT, AND RESOURCES
GEORGE M. HORNBERGER,
University of Virginia,
Chair
RICHARD A. CONWAY,
Union Carbide Corporation (ret.)
THOMAS E. GRAEDEL,
Yale University
THOMAS J. GRAFF,
Environmental Defense Fund
EUGENIA KALNAY,
University of Maryland
DEBRA KNOPMAN,
Progressive Policy Institute
KAI N. LEE,
Williams College
RICHARD A. MESERVE,
Covington & Burling
RADM. JOHN B. MOONEY, JR., USN (ret.),
J. Brad Mooney Associates, Ltd.
HUGH C. MORRIS,
El Dorado Gold Corporation, Vancouver, British Columbia
H. RONALD PULLIAM,
University of Georgia
MILTON RUSSELL,
University of Tennessee
THOMAS C. SCHELLING,
University of Maryland
ANDREW R. SOLOW,
Woods Hole Oceanographic Institution
VICTORIA J. TSCHINKEL,
Landers and Parsons
E-AN ZEN,
University of Maryland
MARY LOU ZOBACK,
U.S. Geological Survey
ROBERT M. HAMILTON, Executive Director
Foreword
A major objective of the International Space Station is learning how to cope with the inherent risks of human spaceflight—how to live and work in space for extended periods. The construction of the station itself provides the first opportunity for doing so.
Prominent among the challenges associated with ISS construction is the large amount of time that astronauts will be spending doing extravehicular activity (EVA), or ''space walks." EVAs from the space shuttle have been extraordinarily successful, most notably the on-orbit repair of the Hubble Space Telescope. But the number of hours of EVA for ISS construction exceeds that of the Hubble repair mission by orders of magnitude. Furthermore, the ISS orbit has nearly twice the inclination to Earth's equator as Hubble's orbit, so it spends part of every 90-minute circumnavigation at high latitudes, where Earth's magnetic field is less effective at shielding impinging radiation. This means that astronauts sweeping through these regions will be considerably more vulnerable to dangerous doses of energetic particles from a sudden solar eruption.
This putative radiation danger prompted the present study. It applies what we have learned from past investigations of solar emanations and their effects on Earth's magnetosphere to assess the risk and find ways to minimize it. The study estimates that the likelihood of having a potentially dangerous solar event during an EVA is indeed very high. It also recommends steps that can be taken immediately, and over the next several years, to provide adequate warning so that the astronauts can be directed to take protective cover inside the ISS or shuttle. The near-term actions include programmatic and operational ways to take advantage of the multiagency assets that currently monitor and forecast space weather, and ways to improve the in situ measurements and the predictive power of current models.
The radiation risk is real, but it is also very susceptible to management. That there have been no known overexposures to date is due partly to such good management. Now it is time to revise the protocols and practices of the past to encompass the new challenges of ISS construction and permanent habitation to ensure that this good record continues in the future.
Claude R. Canizares, Chair
Space Studies Board
Acknowledgments
Preparing this report would not have been possible without the help of the many individuals who provided the Committee on Solar and Space Physics and the Committee on Solar-Terrestrial Research (CSSP/CSTR) with presentations, consultations, and written materials. The committees are especially grateful to the following individuals: for information on the probability of a solar particle event (SPE) coinciding with an International Space Station (ISS) construction mission, Ronald Turner (ANSER Corporation); for information on the properties of penetrating radiation and on the latitudinal cutoff of SPE particles, Don Smart (Air Force Research Laboratory, ret.); for information on the properties and measurements of highly relativistic electrons in the outer radiation belt, Herbert Kroehl (NOAA's National Geophysics Data Center) and Bernard Blake (Aerospace Corporation); for information pertaining to NOAA's Space Environment Center (SEC), Gary Heckman (NOAA-SEC); for information on matters pertaining to mission operations at Johnson Space Center (JSC) and on radiation data taken on Mir and the shuttles, Michael Golightly and Gautam Badhwar (both at JSC); and for information pertaining to radiation risk management during the Apollo era (the SPAN program), Donald Robbins, Alva Hardy, and Rod Rose (all at JSC during the Apollo era).
In addition, CSSP/CSTR wishes to acknowledge the following individuals for informative presentations and interviews at its meetings: for a flight director's perspective, Paul Hill (JSC); for a flight surgeon's perspective, Jeff Jones (JSC); for an astronaut's perspective, Norman Thagard (Florida State University); for information on radiation effects on biological materials and organisms and on research programs pertaining to these, Walter Schimmerling (NASA headquarters), Richard Setlow (Brookhaven National Laboratory), R.J. Michael Fry (Oak Ridge National Laboratory), and Larry Townsend (University of Tennessee); and for information on radiation effects on other than biological materials and on NASA's Space Environment Effects program at Marshall Space Flight Center, Dana Brewer (NASA headquarters) and Janet Barth (Goddard Space Flight Center). The report has also benefited from inputs by members of the National Research Council's Committee on Space Biology and Medicine, which is chaired by Mary J. Osborn; from the Space Studies Board, especially Fran Bagenal; and from Margaret Kivelson, liaison from the Commission on Physical Sciences, Mathematics and Applications to the Space Studies Board.
This report has been reviewed by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the Report Review Committee of the National Research Council (NRC). The purpose of this independent review is to provide candid and critical comments that will assist the authors and the NRC in making the published report as sound as possible and to ensure that the report meets institutional
standards for objectivity, evidence, and responsiveness to the study charge. The contents of the review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. CSSP/CSTR wishes to thank the following individuals for their participation in the review of this report: J. Bernard Blake, the Aerospace Corporation; Joan Feynman, Jet Propulsion Laboratory; R.J. Michael Fry, Oak Ridge National Laboratory; John Grunsfeld, NASA Johnson Space Center; Louis J. Lanzerotti, Lucent Technologies; Edward T. Lu, NASA Johnson Space Center; Frank B. McDonald, University of Maryland; and Donald J. Williams, Johns Hopkins University Applied Physics Laboratory.
Although the individuals listed above have provided many constructive comments and suggestions, responsibility for the final content of this report rests solely with CSSP/CSTR and the NRC.