Space Radiation Hazards and the Vision for Space Exploration

Report of a Workshop

Ad Hoc Committee on the Solar System Radiation Environment and NASA’s Vision for Space Exploration: A Workshop

Space Studies Board

Division on Engineering and Physical Sciences

NATIONAL RESEARCH COUNCIL OF THE NATIONAL ACADEMIES

THE NATIONAL ACADEMIES PRESS

Washington, D.C.
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Space Radiation Hazards and the Vision for Space Exploration: Report of a Workshop Space Radiation Hazards and the Vision for Space Exploration Report of a Workshop Ad Hoc Committee on the Solar System Radiation Environment and NASA’s Vision for Space Exploration: A Workshop Space Studies Board Division on Engineering and Physical Sciences NATIONAL RESEARCH COUNCIL OF THE NATIONAL ACADEMIES THE NATIONAL ACADEMIES PRESS Washington, D.C. www.nap.edu

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Space Radiation Hazards and the Vision for Space Exploration: Report of a Workshop THE NATIONAL ACADEMIES PRESS 500 Fifth Street, N.W. Washington, DC 20001 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 study is based on work supported by Contract NASW-01001 between the National Academy of Sciences and the National Aeronautics and Space Administration. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the agency that provided support for the project. International Standard Book Number-10 0-309-10264-2 International Standard Book Number-13 978-0-309-10264-3 Cover design by Timothy Warchocki. Image courtesy of the National Aeronautics and Space Administration. Copies of this report are available free of charge from: Space Studies Board National Research Council 500 Fifth Street, N.W. Washington, DC 20001 Additional copies of this report are available from the National Academies Press, 500 Fifth Street, N.W., Lockbox 285, Washington, DC 20055; (800) 624-6242 or (202) 334-3313 (in the Washington metropolitan area); Internet, http://www.nap.edu. Copyright 2006 by the National Academy of Sciences. All rights reserved. Printed in the United States of America

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Space Radiation Hazards and the Vision for Space Exploration: Report of a Workshop THE NATIONAL ACADEMIES Advisers to the Nation on Science, Engineering, and 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. Ralph J. Cicerone 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. Wm. 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. Harvey V. Fineberg 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. Ralph J. Cicerone and Dr. Wm. A. Wulf are chair and vice chair, respectively, of the National Research Council. www.national-academies.org

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Space Radiation Hazards and the Vision for Space Exploration: Report of a Workshop OTHER REPORTS OF THE SPACE STUDIES BOARD An Assessment of Balance in NASA’s Science Programs (2006) Assessment of Planetary Protection Requirements for Venus Missions: Letter Report (2006) Distributed Arrays of Small Instruments for Solar-Terrestrial Research: Report of a Workshop (2006) Issues Affecting the Future of the U.S. Space Science and Engineering Workforce (SSB with the Aeronautics and Space Engineering Board [ASEB], 2006) The Astrophysical Context of Life (SSB with the Board on Life Sciences, 2005) Earth Science and Applications from Space: Urgent Needs and Opportunities to Serve the Nation (2005) Extending the Effective Lifetimes of Earth Observing Research Missions (2005) Preventing the Forward Contamination of Mars (2005) Principal-Investigator-Led Missions in the Space Sciences (2005) Priorities in Space Science Enabled by Nuclear Power and Propulsion (SSB with ASEB, 2005) Review of Goals and Plans for NASA’s Space and Earth Sciences (2005) Science in NASA’s Vision for Space Exploration (2005) Solar and Space Physics and Its Role in Space Exploration (2005) Assessment of Options for Extending the Life of the Hubble Space Telescope: Final Report (SSB with ASEB, 2004) Exploration of the Outer Heliosphere and the Local Interstellar Medium: A Workshop Report (2004) Issues and Opportunities Regarding the U.S. Space Program: A Summary Report of a Workshop on National Space Policy (SSB with ASEB, 2004) Plasma Physics of the Local Cosmos (2004) Review of Science Requirements for the Terrestrial Planet Finder: Letter Report (2004) Understanding the Sun and Solar System Plasmas: Future Directions in Solar and Space Physics (2004) Utilization of Operational Environmental Satellite Data: Ensuring Readiness for 2010 and Beyond (SSB with ASEB and the Board on Atmospheric Sciences and Climate [BASC], 2004) Assessment of NASA’s Draft 2003 Earth Science Enterprise Strategy: Letter Report (2003) Assessment of NASA’s Draft 2003 Space Science Enterprise Strategy: Letter Report (2003) Satellite Observations of the Earth’s Environment: Accelerating the Transition of Research to Operations (SSB with ASEB and BASC, 2003) Steps to Facilitate Principal-Investigator-Led Earth Science Missions (2003) The Sun to the Earthand Beyond: Panel Reports (2003) Assessment of Directions in Microgravity and Physical Sciences Research at NASA (2002) New Frontiers in the Solar System: An Integrated Exploration Strategy (2002) The Sun to Earthand Beyond: A Decadal Research Strategy in Solar and Space Physics (2002) Limited copies of these reports are available free of charge from: Space Studies Board National Research Council The Keck Center of the National Academies 500 Fifth Street, N.W., Washington, DC 20001 (202) 334-3477/ssb@nas.edu www.nationalacademies.org/ssb/ssb.html NOTE: Listed according to year of approval for release.

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Space Radiation Hazards and the Vision for Space Exploration: Report of a Workshop AD HOC COMMITTEE ON THE SOLAR SYSTEM RADIATION ENVIRONMENT AND NASA’S VISION FOR SPACE EXPLORATION: A WORKSHOP DANIEL N. BAKER, University of Colorado, Chair LESLIE A. BRABY, Texas A&M University STANLEY CURTIS, University of Washington (retired) JACK R. JOKIPII, University of Arizona WILLIAM S. LEWIS, Southwest Research Institute JACK MILLER, Lawrence Berkeley National Laboratory WALTER SCHIMMERLING, NASA (retired) HOWARD J. SINGER, National Oceanic and Atmospheric Administration LEONARD STRACHAN, Harvard-Smithsonian Center for Astrophysics LAWRENCE W. TOWNSEND, University of Tennessee RONALD E. TURNER, ANSER Corporation THOMAS H. ZURBUCHEN, University of Michigan Staff DWAYNE A. DAY, Study Director ARTHUR CHARO, Senior Program Officer CATHERINE A. GRUBER, Assistant Editor CELESTE NAYLOR, Senior Program Assistant

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Space Radiation Hazards and the Vision for Space Exploration: Report of a Workshop SPACE STUDIES BOARD LENNARD A. FISK, University of Michigan, Chair A. THOMAS YOUNG, Lockheed Martin Corporation (retired), Vice Chair SPIRO K. ANTIOCHOS, Naval Research Laboratory DANIEL N. BAKER, University of Colorado STEVEN J. BATTEL, Battel Engineering CHARLES L. BENNETT, Johns Hopkins University JUDITH A. CURRY, Georgia Institute of Technology JACK D. FARMER, Arizona State University JACK D. FELLOWS, University Corporation for Atmospheric Research JACQUELINE N. HEWITT, Massachusetts Institute of Technology TAMARA E. JERNIGAN, Lawrence Livermore National Laboratory KLAUS KEIL, University of Hawaii DEBRA S. KNOPMAN, RAND Corporation BERRIEN MOORE, III, University of New Hampshire KENNETH H. NEALSON, University of Southern California NORMAN P. NEUREITER, American Association for the Advancement of Science (retired) SUZANNE OPARIL, University of Alabama, Birmingham JAMES PAWELCZYK, Pennsylvania State University RONALD F. PROBSTEIN, Massachusetts Institute of Technology HARVEY D. TANANBAUM, Harvard-Smithsonian Astrophysical Observatory RICHARD H. TRULY, National Renewable Energy Laboratory (retired) JOSEPH F. VEVERKA, Cornell University WARREN M. WASHINGTON, National Center for Atmospheric Research GARY P. ZANK, University of California, Riverside MARCIA S. SMITH, Director

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Space Radiation Hazards and the Vision for Space Exploration: Report of a Workshop Preface In October 2005 a group of approximately 120 experts on solar and space physics and the effects of radiation on humans and spacecraft met for a workshop at the Wintergreen conference facilities near Charlottesville, Virginia. This workshop followed other efforts by solar and space physics scientists to address ways in which their work could be focused on support for NASA’s Vision for Space Exploration (see Box P.1). These earlier meetings included a RHESSI-SOHO-TRACE Workshop in December 20041 that had recommended a meeting near Washington, D.C., in the fall of 2005 to bring together NASA Exploration operations and engineering personnel and scientists. It also followed a workshop organized by NASA’s Living With a Star (LWS) program, held on April 5-6, 2004, in Washington, D.C., to examine existing and planned LWS science missions that contribute to the enabling of proposed human lunar and Mars missions. At nearly the same time, the Committee on Solar and Space Physics (CSSP) of the National Research Council’s (NRC’s) Space Studies Board independently began planning for a study on space environmental hazards. The CSSP agreed to cosponsor the workshop and to prepare this NRC workshop report. A list of workshop participants and the agenda are provided in Appendix C. The workshop participants made a significant contribution in helping to assess the current level of understanding of solar and space physics, in looking at some of the issues faced by the NASA space radiation program as it deals with radiation effects on humans, in focusing on the challenges of ensuring the reliable functioning of instruments and machines in space, and in illustrating how progress in understanding, defining, and, ultimately, making timely predictions of the space radiation environment is essential for implementation of the Vision for Space Exploration. 1 RHESSI, Ramati High Energy Solar Spectrographic Imager; SOHO, Solar and Heliospheric Observatory; TRACE, Transition Region and Coronal Explorer.

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Space Radiation Hazards and the Vision for Space Exploration: Report of a Workshop BOX P.1 NASA’S VISION FOR SPACE EXPLORATION Complete the International Space Station (ISS) by 2010 Research on ISS will focus on long-term effects of space travel on humans After ISS is complete, retire the Space Shuttle Begin developing a new vehicle for human exploration, the Crew Exploration Vehicle (CEV) First crewed vehicle to explore beyond Earth orbit since the Apollo Develop and test by 2008 First human mission for the CEV no later than 2014 Main purpose will be to leave Earth orbit; the vehicle will also ferry astronauts to and from ISS after shuttle retirement Return to the Moon by 2020, as launching point for missions beyond Robotic probes to the lunar surface by 2008 Robotic probes to the lunar surface by 2008 Human mission as early as 2015—goal of living and working there for increasingly extended periods of time With the experience and knowledge gained on the Moon, take the next steps of space exploration: human missions to Mars and to worlds beyond SOURCE: NASA, The Vision for Space Exploration, NP-2004-01-334-HQ, NASA, Washington, D.C., 2004. Many of the participants at the conference had attended the April 2004 Living With a Star workshop and stated that there was a distinct change in attitude between that activity and the Wintergreen Workshop. At the Wintergreen Workshop many of the scientists recognized that there is significant overlap in interests between the solar and space physics community and the human spaceflight community and that the space physics community can assist in attaining the goals of the Vision for Space Exploration. Those communities had not cooperated closely before, but the Wintergreen Workshop demonstrated that such cooperation would be necessary in order to implement the Vision for Space Exploration. This report addresses the importance of the following: The development of predictive and forecast tools by the solar and space physics community, Improved knowledge transfer of present scientific capabilities to the operational environment, and Continued close cooperation between space scientists and the radiation and health science communities. This report provides a synopsis of the state of the art of the space weather elements related to human and robotic exploration missions. However, understanding solar and space physics continues to be a challenging problem in its own right, with high intellectual content that requires advances in physics,

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Space Radiation Hazards and the Vision for Space Exploration: Report of a Workshop geophysics, and computation. NASA can ill afford to neglect to invest in this essential component of the agency’s intellectual capital and, hence, its future. The ad hoc committee thanks the many organizers and community members who helped to make this effort a success. It is the hope of the committee that the communities that came together for the Wintergreen Workshop will continue to work closely and cooperatively as the Vision for Space Exploration continues to evolve.

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Space Radiation Hazards and the Vision for Space Exploration: Report of a Workshop Acknowledgment of Reviewers This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the National Research Council’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its 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 review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their review of this report: Timothy Bastian, National Radio Astronomy Observatory, Anthony Chan, Rice University, Philip Hahnfeldt, Tufts University School of Medicine, Joseph Kunches, National Oceanic and Atmospheric Administration, and George Paulikas, The Aerospace Corporation (retired). Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations, nor did they see the final draft of the report before its release. The review of this report was overseen by Eugene Parker, University of Chicago (emeritus professor). Appointed by the National Research Council, he was responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee and the institution.

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Space Radiation Hazards and the Vision for Space Exploration: Report of a Workshop Contents     EXECUTIVE SUMMARY   1 1   RADIATION RISKS AND THE VISION FOR SPACE EXPLORATION   7      The Space Radiation Environment,   12      Galactic Cosmic Radiation,   13      Solar Energetic Particles,   13      Trapped Radiation,   14      Secondary Radiation,   14      Radiation Risks,   14      Hardware Risks,   20      References,   22 2   SPECIFYING AND PREDICTING THE SPACE RADIATION ENVIRONMENT   24      Heliospheric Magnetic Field,   24      Galactic Cosmic Rays,   25      Solar Energetic Particles,   26      Coronal Mass Ejections,   28      Flares and Active Regions,   30      Prospects for Long- and Short-Term Forecast Models,   31      Long-Term Forecasts (Years to Decades),   31      Short-Term Forecasts (Nowcasts to Days and Weeks),   32      Solar Wind and Heliospheric Models,   34      Models for Coronal Mass Ejections and Flares and for Solar Energetic Particles,   34

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Space Radiation Hazards and the Vision for Space Exploration: Report of a Workshop      Ongoing Integrated Modeling Activities,   35      What Is Possible for the Future?,   35      Near-Term Results (Up to 2015),   36      Far-Term Results (After 2015),   36      References,   36 3   OPERATIONAL STRATEGIES FOR SPACE WEATHER SUPPORT   38      Current Operations Support (Space Shuttle and International Space Station Missions in Low Earth Orbit),   38      Preflight and Extravehicular Activity Crew Exposure Projections,   39      Radiological Support During Missions,   39      Crew Exposure Modeling Capability,   40      Radiation Monitoring Instruments and Dosimeters,   40      Solar and Space Physics Support Areas for the Future,   42      Systems Approach to Providing Space Weather Support to the Vision for Space Exploration,   43      Components of a Space Weather Risk Mitigation Architecture,   43      Lunar Hardware Elements,   46      Mars Hardware Elements,   49      Knowledge-to-Operations Transition,   52      References,   53 4   SUMMARY AND WORKSHOP CONCLUSIONS   54      Understanding of Solar Physics,   55      Fundamental Understanding of Heliophysics,   55      Solar Energetic Particle Event Predictions and Forecast Prospects,   56      Long-Timescale Changes in Galactic Cosmic Radiation,   56      Worst-Case Solar Particle Events,   57      Summary,   58     APPENDIXES          A  Reports of the Working Groups   61      B  Statement of Task   78      C  Workshop Participants and Agenda   79      D  Biographies of Committee Members and Staff   84      E  Acronyms   89