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.
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Support for this project was provided by Contract NASW 4627 and Contract NASW 96013 between the National Academy of Sciences and the National Aeronautics and Space Administration.
Copyright 1996 by the National Academy of Sciences. All rights reserved.
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TASK GROUP ON THE BIOLOGICAL EFFECTS OF SPACE RADIATION
RICHARD SETLOW,
Brookhaven National Laboratory,
Chair
JOHN F. DICELLO,
Johns Hopkins University School of Medicine
R.J. MICHAEL FRY,
Oak Ridge National Laboratory
JOHN B. LITTLE,
Harvard University School of Public Health
R. JULIAN PRESTON,
Chemical Industry Institute of Toxicology
JAMES B. SMATHERS,
University of California, Los Angeles
ROBERT L. ULLRICH,
University of Texas Medical Branch, Galveston
SANDRA J. GRAHAM, Study Director
SHOBITA PARTHASARATHY, Research Assistant
VICTORIA P. FRIEDENSEN, Former Senior Program Assistant
CATHY GRUBER, Senior Program Assistant
SPACE STUDIES BOARD
CLAUDE R. CANIZARES,
Massachusetts Institute of Technology,
Chair
MARK R. ABBOTT,
Oregon State University
JOHN A. ARMSTRONG,*
IBM Corporation (retired)
JAMES P. BAGIAN,
Environmental Protection Agency
DANIEL N. BAKER,
University of Colorado
LAWRENCE BOGORAD,
Harvard University
DONALD E. BROWNLEE,
University of Washington
JOHN J. DONEGAN,
John Donegan Associates, Inc.
GERARD W. ELVERUM, JR.,
TRW Space and Technology Group
ANTHONY W. ENGLAND,
University of Michigan
DANIEL J. FINK,*
D.J. Fink Associates, Inc.
MARTIN E. GLICKSMAN,
Rensselaer Polytechnic Institute
RONALD GREELEY,
Arizona State University
BILL GREEN, former member,
U.S. House of Representatives
NOEL W. HINNERS,*
Lockheed Martin Astronautics Company
ANDREW H. KNOLL,
Harvard University
JANET G. LUHMANN,
University of California, Berkeley
JOHN H. McELROY,*
University of Texas, Arlington
ROBERTA BALSTAD MILLER,
CIESIN
BERRIEN MOORE III,
University of New Hampshire
KENNETH H. NEALSON,
University of Wisconsin
MARY JANE OSBORN,
University of Connecticut Health Center
SIMON OSTRACH,
Case Western Reserve University
MORTON B. PANISH,
AT&T Bell Laboratories (retired)
CARLÉ M. PIETERS,
Brown University
MARCIA J. RIEKE,
University of Arizona
JOHN A. SIMPSON,
Enrico Fermi Institute
ROBERT E. WILLIAMS,
Space Telescope Science Institute
MARC S. ALLEN, Director
COMMISSION ON PHYSICAL SCIENCES, MATHEMATICS, AND APPLICATIONS
ROBERT J. HERMANN,
United Technologies Corporation,
Co-chair
W. CARL LINEBERGER,
University of Colorado,
Co-chair
PETER M. BANKS,
Environmental Research Institute of Michigan
LAWRENCE D. BROWN,
University of Pennsylvania
RONALD G. DOUGLAS,
Texas A&M University
JOHN E. ESTES,
University of California, Santa Barbara
L. LOUIS HEGEDUS,
Elf Atochem North America, Inc.
JOHN E. HOPCROFT,
Cornell University
RHONDA J. HUGHES,
Bryn Mawr College
SHIRLEY A. JACKSON,
U.S. Nuclear Regulatory Commission
KENNETH H. KELLER,
University of Minnesota
KENNETH I. KELLERMANN,
National Radio Astronomy Observatory
MARGARET G. KIVELSON,
University of California, Los Angeles
DANIEL KLEPPNER,
Massachusetts Institute of Technology
JOHN KREICK,
Sanders, a Lockheed Martin Company
MARSHA I. LESTER,
University of Pennsylvania
THOMAS A. PRINCE,
California Institute of Technology
NICHOLAS P. SAMIOS,
Brookhaven National Laboratory
L.E. SCRIVEN,
University of Minnesota
SHMUEL WINOGRAD,
IBM T.J. Watson Research Center
CHARLES A. ZRAKET,
MITRE Corporation (retired)
NORMAN METZGER, Executive Director
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Foreword
Astronauts who venture beyond the protection of Earth's atmosphere and magnetosphere risk exposure to levels of radiation far exceeding those on Earth. Of all the risks they face, this one is probably the most straightforward to control—by providing adequate shielding. However, because shielding adds weight, cost, and complexity to space vehicles, it is very important for designers to have a good, quantitative understanding of the true risk and its degree of certainty.
This report assesses our understanding of radiation hazards in space. It also considers the additional research needed to reduce the areas of uncertainty, research that must be completed prior to undertaking the detailed design of a vehicle carrying crew members into space for periods of extended exposure. The report finds that it will take more than a decade of research to answer even the narrowest set of key questions, although happily the needed studies can all be conducted on the ground rather than in space.
The nation has backed away from a specific timetable for human exploration of the moon and Mars. Yet it seems plausible that such expeditions will be mounted sometime in the first quarter of the 21st century, especially given the recent resurgence of interest in possible life on Mars from the study of meteorites. It becomes clear, when the lengthy time scale of the research is also taken into account, that the present report is indeed timely and should receive prompt consideration by NASA planners.
CLAUDE R. CANIZARES, CHAIR
SPACE STUDIES BOARD
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Preface
The study that is the subject of this report was initiated as a result of a series of discussions between the leaders of NASA's Office of Life and Microgravity Sciences and Applications (OLMSA), NASA's Life and Biomedical Sciences Division (LBSAD), and the Space Studies Board's Committee on Space Biology and Medicine (CSBM). In order to address concerns within NASA and CSBM regarding the many uncertainties in the understanding of radiation hazards to the crew of long-duration missions in space, CSBM formed an expert task group on radiation biology and physics whose members had no direct involvement with NASA's radiation programs. A CSBM member with the appropriate expertise was appointed to lead the group.
The Task Group on the Biological Effects of Space Radiation (TGBESR) was asked to review current knowledge on the effects of long-term exposure to radiation in a space environment and to consider NASA radiation shielding requirements for orbital and interplanetary spacecraft. The task group was charged with assessing the adequacy of NASA planning for the protection of humans from radiation in those environments and with making recommendations regarding needed research and/or new shielding requirements. Where feasible, the task group would also provide NASA with radiation safety guidelines.
Early in the study the task group was informed by NASA that plans for the international space station were at such an advanced stage that any recommendations affecting shielding of orbital craft could not be implemented by the agency. The task group therefore decided to concentrate on the radiation hazards of interplanetary missions. Further, at the urging of NASA, the task group has attempted to provide reasonable estimates of time lines for completing the radiation research it has recommended.
Although the recommendations of the task group are published here as a separate and independent report of TGBESR, it is the intent of CSBM that this report will also form the basis of a section in a space life sciences strategy report being prepared by CSBM for publication at a later date.
During the course of this study the task group was briefed extensively by representatives of OLMSA and LBSAD regarding NASA's planning for deep-space missions and projections for radiation shielding. The task group also received in-depth technical briefings on the status of NASA's radiation research and the agency's current understanding of radiation hazards, and it consulted a wide range of technical documentation. When verification or additional details of prior research were needed, task group members made direct queries to the pertinent investigators in the radiation research community.
A number of individuals who assisted the task group by supplying information deserve special thanks for their contributions: Harry Holloway, Frank Sulzman, and Walter Schimmerling of NASA headquarters; John Wilson of NASA Langley Research Center; Amy Kronenberg of Lawrence Berkeley National Laboratory; and Gregory Nelson of the Jet Propulsion Laboratory.
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