Assessment of Planetary Protection
Requirements for Spacecraft Missions to
Committee on Planetary Protection Standards for Icy Bodies in the Outer Solar System
Space Studies Board
Division on Engineering and Physical Sciences
NATIONAL RESEARCH COUNCIL
OF THE NATIONAL ACADEMIES
THE NATIONAL ACADEMIES PRESS
THE NATIONAL ACADEMIES PRESS 500 Fifth Street, NW 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 NNH06CE15B 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 authors and do not necessarily reflect the views of the agency that provided support for the project.
Cover: Cover design by Penny E. Margolskee. The false-color mosaic image of the “tiger stripe” fractures in the southern polar region of Saturn’s moon Enceladus was constructed from data collected at ultraviolet, green, and near-infrared wavelengths by the Cassini spacecraft during its close flyby of Enceladus on August 11, 2008. Enceladus’s striking plumes emanate from discrete locations along the “tiger stripes.” Courtesy of NASA/Jet Propulsion Laboratory (JPL)/Space Science Institute. Inset, left: An artist’s impression of the New Horizons spacecraft during its flyby of the Pluto-Charon system in July 2015. Courtesy of Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute. Inset, center: Enigmatic plumes of ice particles, water vapor, and trace organic compounds emanate from the southern polar region of Saturn’s moon Enceladus. This false-color image was created from data collected by the Cassini spacecraft on November 27, 2005, when it was 148,000 km from Enceladus. Courtesy of NASA/JPL/Space Science Institute. Inset, right: An artist’s impression of the proposed Europa Clipper spacecraft. This Jupiter-orbiting spacecraft is designed to undertake intensive observations of Europa during a series of close flybys. Courtesy of NASA/JPL.
International Standard Book Number-13: 978-0-309-25675-9
International Standard Book Number-10: 0-309-25675-5
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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.
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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. Charles M. Vest are chair and vice chair, respectively, of the National Research Council.
OTHER REPORTS OF THE SPACE STUDIES BOARD
Assessment of a Plan for U.S. Participation in Euclid (Board on Physics and Astronomy [BPA] and Space Studies Board [SSB], 2012)
Earth Science and Applications from Space: A Midterm Assessment of NASA’s Implementation of the Decadal Survey [prepublication] (SSB, 2012)
Report of the Panel on Implementing Recommendations from the New Worlds, New Horizons Decadal Survey (BPA and SSB, 2012, released in 2010)
Technical Evaluation of the NASA Model for Cancer Risk to Astronauts Due to Space Radiation (SSB, 2012)
Assessment of Impediments to Interagency Collaboration on Space and Earth Science Missions (SSB, 2011)
Panel Reports—New Worlds, New Horizons in Astronomy and Astrophysics (BPA and SSB, 2011)
Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era (SSB, 2011)
Sharing the Adventure with the Public—The Value and Excitement of “Grand Questions” of Space Science and Exploration: Summary of a Workshop (SSB, 2011)
Vision and Voyages for Planetary Science in the Decade 2013-2022 (SSB, 2011)
Capabilities for the Future: An Assessment of NASA Laboratories for Basic Research (Laboratory Assessments Board with SSB and Aeronautics and Space Engineering Board [ASEB], 2010)
Controlling Cost Growth of NASA Earth and Space Science Missions (SSB, 2010)
Defending Planet Earth: Near-Earth-Object Surveys and Hazard Mitigation Strategies: Final Report (SSB with ASEB, 2010)
An Enabling Foundation for NASA’s Space and Earth Science Missions (SSB, 2010)
Forging the Future of Space Science: The Next 50 Years (SSB, 2010)
Life and Physical Sciences Research for a New Era of Space Exploration: An Interim Report (SSB with ASEB, 2010)
New Worlds, New Horizons in Astronomy and Astrophysics (BPA and SSB, 2010)
Revitalizing NASA’s Suborbital Program: Advancing Science, Driving Innovation, and Developing a Workforce (SSB, 2010)
America’s Future in Space: Aligning the Civil Space Program with National Needs (SSB with ASEB, 2009)
Approaches to Future Space Cooperation and Competition in a Globalizing World: Summary of a Workshop (SSB with ASEB, 2009)
Assessment of Planetary Protection Requirements for Mars Sample Return Missions (SSB, 2009)
Near-Earth Object Surveys and Hazard Mitigation Strategies: Interim Report (SSB with ASEB, 2009)
A Performance Assessment of NASA’s Heliophysics Program (SSB, 2009)
Radioisotope Power Systems: An Imperative for Maintaining U.S. Leadership in Space Exploration (SSB with ASEB, 2009)
Launching Science: Science Opportunities Provided by NASA’s Constellation System (SSB with ASEB, 2008)
Opening New Frontiers in Space: Choices for the Next New Frontiers Announcement of Opportunity (SSB, 2008)
Limited copies of these reports are available free of charge from:
Space Studies Board
National Research Council
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COMMITTEE ON PLANETARY PROTECTION STANDARDS FOR ICY BODIES IN THE OUTER SOLAR SYSTEM
MITCHELL L. SOGIN, Marine Biological Laboratory, Chair
GEOFFREY COLLINS, Wheaton College, Vice Chair
AMY BAKER, Technical Administrative Services
JOHN A. BAROSS, University of Washington
AMY BARR, Brown University
WILLIAM V. BOYNTON, University of Arizona
CHARLES S. COCKELL, University of Edinburgh
MICHAEL J. DALY, Uniformed Services University of the Health Sciences
JOSEPH R. FRAGOLA, Valador Incorporated
ROSALY M.C. LOPES, Jet Propulsion Laboratory, California Institute of Technology
KENNETH H. NEALSON, University of Southern California
DOUGLAS S. STETSON, Space Science and Exploration Consulting Group
MARK H. THIEMENS, University of California, San Diego
DAVID H. SMITH, Senior Program Officer, Study Director
CATHERINE A. GRUBER, Editor
RODNEY N. HOWARD, Senior Project Assistant
HEATHER D. SMITH, National Academies Christine Mirzayan Science and Technology Policy Fellow
ANNA B. WILLIAMS, National Academies Christine Mirzayan Science and Technology Policy Fellow
KATIE DAUD, Lloyd V. Berkner Space Policy Intern
DANIELLE PISKORZ, Lloyd V. Berkner Space Policy Intern
MICHAEL H. MOLONEY, Director, Space Studies Board
SPACE STUDIES BOARD
CHARLES F. KENNEL, Scripps Institution of Oceanography, University of California, San Diego, Chair
JOHN KLINEBERG, Space Systems/Loral (retired), Vice Chair
MARK R. ABBOTT, Oregon State University
STEVEN J. BATTEL, Battel Engineering
YVONNE C. BRILL, Aerospace Consultant
ELIZABETH R. CANTWELL, Oak Ridge National Laboratory
ANDREW B. CHRISTENSEN, Dixie State College and The Aerospace Corporation
ALAN DRESSLER, The Observatories, Carnegie Institution for Science
JACK D. FELLOWS, University Corporation for Atmospheric Research
HEIDI B. HAMMEL, Association of Universities for Research in Astronomy, Inc.
FIONA A. HARRISON, California Institute of Technology
ANTHONY C. JANETOS, University of Maryland
JOAN JOHNSON-FREESE, Naval War College
ROBERT P. LIN, University of California, Berkeley
MOLLY K. MACAULEY, Resources for the Future
JOHN F. MUSTARD, Brown University
ROBERT T. PAPPALARDO, Jet Propulsion Laboratory, California Institute of Technology
JAMES PAWELCZYK, Pennsylvania State University
MARCIA J. RIEKE, University of Arizona
DAVID N. SPERGEL, Princeton University
WARREN M. WASHINGTON, National Center for Atmospheric Research
CLIFFORD M. WILL, Washington University
THOMAS H. ZURBUCHEN, University of Michigan
MICHAEL H. MOLONEY, Director
CARMELA J. CHAMBERLAIN, Administrative Coordinator
TANJA PILZAK, Manager, Program Operations
CELESTE A. NAYLOR, Information Management Associate
CHRISTINA O. SHIPMAN, Financial Officer
SANDRA WILSON, Financial Assistant
In a letter sent to the National Research Council’s (NRC’s) Space Studies Board (SSB) Chair Charles F. Kennel on May 20, 2010, Edward J. Weiler, NASA’s associate administrator for the Science Mission Directorate (SMD), explained that understanding of the planetary protection requirements for spacecraft missions to Europa and the other icy bodies of the outer solar system should keep pace with our increasing knowledge of these unique planetary environments. Specific advice regarding planetary protection requirements for Europa is contained in the 2000 NRC report Preventing the Forward Contamination of Europa.1 NRC advice concerning other icy bodies is either nonexistent or contained in reports that are now outdated. As NASA and other space agencies prepare for future missions to the icy bodies of the outer solar system, it is appropriate to review the findings of the 2000 Europa report and to update and extend its recommendations to cover the entire range of icy bodies—i.e., asteroids, satellites, Kuiper belt objects, and comets. These considerations led Dr. Weiler to request that the NRC revisit the planetary protection requirements for missions to icy solar system bodies in light of current scientific understanding and ongoing improvements in mission-enabling technologies. In particular, the NRC was asked to consider the following subjects and make recommendations:
• The possible factors that usefully could be included in a Coleman-Sagan formulation describing the probability that various types of missions might contaminate with Earth life any liquid water, either naturally occurring or induced by human activities, on or within specific target icy bodies or classes of objects;
• The range of values that can be estimated for the above factors based on current knowledge, as well as an assessment of conservative values for other specific factors that might be provided to missions targeting individual bodies or classes of objects; and
• Scientific investigations that could reduce the uncertainty in the above estimates and assessments, as well as technology developments that would facilitate implementation of planetary protection requirements and/or reduce the overall probability of contamination.
In response to this request, the Committee on Planetary Protection Standards for Icy Bodies in the Outer Solar System was established in September 2010. The committee held organizational teleconferences on November 17 and December 15 in 2010. The committee’s first meeting to hear presentations relating to its task took place at
1 National Research Council, Preventing the Forward Contamination of Europa, National Academy Press, Washington, D.C., 2000.
the National Academies’ Keck Center in Washington, D.C., on January 31 through February 2, 2011. Additional presentations and discussions were heard during a meeting held at the Arnold and Mabel Beckman Center of the National Academies in Irvine, California, on March 16-18 and during a teleconference held on May 13. The committee’s final meeting was held at the Beckman Center on June 14-16.
The work of the committee was made easier thanks to the important help, advice, and comments provided by numerous individuals from a variety of public and private organizations. These include the following: Douglas Bernard (Jet Propulsion Laboratory), Brent Christner (Louisiana State University), Benton C. Clark (Space Science Institute), Karla B. Clark (Jet Propulsion Laboratory), Catharine A. Conley (NASA Headquarters), Steven D’Hondt (University of Rhode Island), Will Grundy (Lowell Observatory), Torrence V. Johnson (Jet Propulsion Laboratory), Ralph D. Lorenz (Johns Hopkins University, Applied Physics Laboratory), Wayne L. Nicholson (University of Florida), Curt Niebur (NASA Headquarters), Robert T. Pappalardo (Jet Propulsion Laboratory), Chris Paranicas (Johns Hopkins University, Applied Physics Laboratory), P. Buford Price, Jr. (University of California, Berkeley), Louise Prockter (Johns Hopkins University, Applied Physics Laboratory), John D. Rummel (East Carolina University), Daniel F. Smith (Advanced Sterilization Products), John Spencer (Southwest Research Institute), J. Andrew Spry (Jet Propulsion Laboratory), Elizabeth Turtle (Johns Hopkins University, Applied Physics Laboratory), Christopher R. Webster (Jet Propulsion Laboratory), and Yuri Wolf (National Library of Medicine, National Institutes of Health).
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 NRC’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the authors and the NRC 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.
The committee wishes to thank the following individuals for their participation in the review of this report: John R. Battista, Louisiana State University; Chris F. Chyba, Princeton University; Gerald W. Elverum, TRW Space Science and Defense; Kevin P. Hand, Jet Propulsion Laboratory; Margaret G. Kivelson, University of California, Los Angeles; Christopher P. McKay, NASA Ames Research Center; Ronald F. Probstein, Massachusetts Institute of Technology; John D. Rummel, East Carolina University; and Yuri I. Wolf, National Library of Medicine, National Institutes of Health.
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 Larry W. Esposito, University of Colorado, Boulder. Appointed by the NRC, 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.