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Preventing the Forward Contamination of Mars PREVENTING THE FORWARD CONTAMINATION OF MARS Committee on Preventing the Forward Contamination of Mars 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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Preventing the Forward Contamination of Mars 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 was 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 0-309-09724-X Cover: Main image—Sunlight on an icy martian crater, an image from the Mars Express spacecraft showing a pocket of water ice in a martian crater. Source—ESA/DLR/Freie Universitaet Berlin (G. Neukum). Reprinted by permission from Macmillan Publishers Ltd., “Snapshot: Sunlight on an Icy Martian Crater,” Nature 435:9, June 9, 2005. Copyright 2005. Additional images—Artist’s impressions of (top to bottom) the Mars Reconnaissance Orbiter, a Mars lander under parachute, and the proposed Mars Deep Driller. Courtesy of NASA/JPL. 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 also 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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Preventing the Forward Contamination of Mars 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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Preventing the Forward Contamination of Mars OTHER REPORTS OF THE SPACE STUDIES BOARD 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) Principal-Investigator-Led Missions in the Space Sciences (2005) Priorities in Space Science Enabled by Nuclear Power and Propulsion (SSB with the Aeronautics and Space Engineering Board, 2005) Review of Goals and Plans for NASA’s Space and Earth Sciences (2005) Review of NASA Plans for the International Space Station (2005) Science in NASA’s Vision for Space Exploration (2005) Assessment of Options for Extending the Life of the Hubble Space Telescope: Final Report (SSB with Aeronautics and Space Engineering Board, 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 Aeronautics and Space Engineering Board, 2004) Plasma Physics of the Local Cosmos (2004) Review of Science Requirements for the Terrestrial Planet Finder: Letter Report (2004) Solar and Space Physics and Its Role in Space Exploration (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 Aeronautics and Space Engineering Board and Board on Atmospheric Sciences and Climate, 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 Aeronautics and Space Engineering Board and Board on Atmospheric Sciences and Climate, 2003) Steps to Facilitate Principal-Investigator-Led Earth Science Missions (2003) The Sun to the Earth—and Beyond: Panel Reports (2003) 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 firstname.lastname@example.org www.nationalacademies.org/ssb/ssb.html NOTE: Listed according to year of approval for release.
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Preventing the Forward Contamination of Mars COMMITTEE ON PREVENTING THE FORWARD CONTAMINATION OF MARS CHRISTOPHER F. CHYBA, SETI Institute and Stanford University,* Chair STEPHEN CLIFFORD, Lunar and Planetary Institute ALAN DELAMERE, Ball Aerospace and Technologies (retired) MARTIN S. FAVERO, Johnson & Johnson Company ERIC J. MATHUR, Diversa Corporation JOHN C. NIEHOFF, Science Applications International Corporation GIAN GABRIELE ORI, IRSPS – G. d’Annunzio University, Chieti-Pescara, Italy DAVID A. PAIGE, University of California, Los Angeles ANN PEARSON, Harvard University JOHN C. PRISCU, Montana State University MARGARET S. RACE, SETI Institute MITCHELL L. SOGIN, Marine Biological Laboratory CRISTINA TAKACS-VESBACH, University of New Mexico Staff PAMELA L. WHITNEY, Study Director EMILIE CLEMMENS, Christine Mirzayan Science and Technology Policy Graduate Fellow AMANDA SHARP, Research Assistant CARMELA J. CHAMBERLAIN, Senior Project Assistant CATHERINE A. GRUBER, Assistant Editor * Princeton University as of July 2005.
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Preventing the Forward Contamination of Mars SPACE STUDIES BOARD LENNARD A. FISK, University of Michigan, Chair GEORGE A. PAULIKAS, The Aerospace Corporation (retired), Vice Chair SPIROS K. ANTIOCHOS,† Naval Research Laboratory DANIEL N. BAKER, University of Colorado ANA P. BARROS,* Duke University RETA F. BEEBE, New Mexico State University ROGER D. BLANDFORD, Stanford University RADFORD BYERLY, JR., University of Colorado JUDITH A. CURRY, Georgia Institute of Technology JACK D. FARMER, Arizona State University JACQUELINE N. HEWITT, Massachusetts Institute of Technology DONALD INGBER, Harvard Medical Center RALPH H. JACOBSON, The Charles Stark Draper Laboratory (retired) TAMARA E. JERNIGAN, Lawrence Livermore National Laboratory KLAUS KEIL,† University of Hawaii MARGARET G. KIVELSON,* University of California, Los Angeles DEBRA S. KNOPMAN,† RAND Corporation CALVIN W. LOWE, Bowie State University HARRY Y. McSWEEN, JR.,* University of Tennessee BERRIEN MOORE III, University of New Hampshire NORMAN NEUREITER, Texas Instruments (retired) SUZANNE OPARIL, University of Alabama, Birmingham RONALD F. PROBSTEIN, Massachusetts Institute of Technology DENNIS W. READEY, Colorado School of Mines ANNA-LOUISE REYSENBACH,* Portland State University ROALD S. SAGDEEV,* University of Maryland CAROLUS J. SCHRIJVER,* Lockheed Martin Solar and Astrophysics Laboratory HARVEY D. TANANBAUM, Smithsonian Astrophysical Observatory RICHARD H. TRULY,† National Renewable Energy Laboratory (retired) J. CRAIG WHEELER, University of Texas, Austin A. THOMAS YOUNG, Lockheed Martin Corporation (retired) GARY P. ZANK,† University of California, Riverside JOSEPH K. ALEXANDER, Director * Member until June 30, 2005. † Member starting July 1, 2005.
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Preventing the Forward Contamination of Mars Preface Mars has been called “the most nearly similar to Earth of all the planets and one of the most likely repositories for extraterrestrial life among them.”1 Its proximity to Earth and its moderate climate make the planet more accessible for study than others in the solar system. The Viking lander missions in the 1970s explored two locations on Mars that suggested a dry, barren environment hostile to life.2 However, recent spacecraft and robotic probes to Mars, including the Mars Global Surveyor, Mars Odyssey, the twin Mars Exploration Rovers Spirit and Opportunity, and the European Mars Express mission, have yielded a wealth of data that are significantly changing our understanding of the planet. Mars is now recognized as a heterogeneous planet of multiple environments, some of which might offer conditions suitable for extant or past life. In addition, studies of biology in extreme environments continue to expand the known range of environmental parameters compatible with life, and life-detection techniques have become ever more sensitive, enhancing the capabilities to find past or present life on the planet, should it exist. Indeed, the search for past and present life on Mars is the first of four nearly equal objectives in the Mars exploration strategy of the National Aeronautics and Space Administration (NASA).3 In light of these developments, the need to protect against contamination from Earth-borne organisms has become increasingly important. NASA thus requested that the National Research Council’s (NRC’s) Space Studies Board (SSB) examine existing planetary protection measures for Mars and recommend changes and further research to improve such measures. Specifically, the Space Studies Board’s Committee on Preventing the Forward Contamination of Mars accepted the following statement of task: 1 National Research Council, Assessment of Mars Science and Mission Priorities, National Academy Press, Washington, D.C., 2001, p. vii. 2 National Research Council, Recommendations on Quarantine Policy for Mars, Jupiter, Saturn, Uranus, Neptune, and Titan, National Academy Press, Washington, D.C., 1978, pp. 3-13. 3 “The overarching objectives for MEP [NASA’s Mars Exploration Program] are: Life, Climate, Geology, and Preparation for Human Exploration. First among these objectives of nearly equal priority is Life.” See MSPSG, Mars Science Program Synthesis Group: Mars Exploration Strategy, 2009-2020, D.J. McCleese, ed., JPL 400-1131, Jet Propulsion Laboratory, Pasadena, Calif., 2004, p. 4. In 2004, the Mars Exploration Program Analysis Group (MEPAG) endorsed the same four objectives but explicitly did not prioritize them. See MEPAG, Scientific Goals, Objectives, Investigations, and Priorities: 2004, unpublished document, available at <mepag.jpl.nasa.gov/reports/index.html>.
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Preventing the Forward Contamination of Mars Assess and recommend levels of cleanliness and bioload reduction required to prevent the forward contamination of Mars by future spacecraft missions (orbiters, atmospheric missions, landers, penetrators, and drills), given current understanding of the martian environment and of terrestrial microorganisms. The committee’s recommendations should take into account the full spectrum of environments on, above, and under present-day Mars, and the various ways that spaceflight missions may access them, intentionally or inadvertently. Review methods used to achieve and measure the appropriate level of cleanliness and bioload reduction for Mars spacecraft and recommend protocol revisions and/or additions in light of recent advances in science and technology. Identify scientific investigations that should be accomplished to reduce the uncertainty in the above assessments. The task specified that, to the maximum possible extent, the recommendations should be developed to be compatible with an implementation that would use the regulatory framework for planetary protection currently in use by NASA and the Committee on Space Research (COSPAR). STUDY APPROACH AND PROCESS The membership and qualifications of the Committee on Preventing the Forward Contamination of Mars are shown in Appendix A. The committee’s work follows the NRC’s previous advice to NASA on Mars planetary protection as provided in Recommendations on Quarantine Policy for Mars, Jupiter, Saturn, Uranus, Neptune, and Titan (NRC, 1978) and Biological Contamination of Mars: Issues and Recommendations (NRC, 1992); advice provided on the planetary protection of Europa in Preventing the Forward Contamination of Europa (NRC, 2000); advice provided in Mars Sample Return: Issues and Recommendations (NRC, 1997) on back contamination from samples collected on Mars and delivered to Earth; and advice in Evaluating the Biological Potential in Samples Returned from Planetary Satellites and Small Solar System Bodies (NRC, 1998) on samples returned from other solar system bodies. The recommendations relevant to the current study that were made in the 1992 and 2000 reports are summarized in Appendix B. The committee explored a number of issues. It revisited arguments on the probability of contamination and the probability for the growth of Earth microorganisms on Mars as detailed in previous NRC reports, and it reevaluated that material in light of new knowledge. The committee took into account the question of liquid water on Mars; new knowledge about extremophilic microorganisms on Earth; new life-detection and bioburden-reduction techniques; the upcoming Mars Exploration Program; the potential for orbiter and lander crashes on Mars; the possible natural delivery of terrestrial microorganisms to Mars via meteorites launched from Earth; the implications for planetary protection of past spacecraft landings and crashes on Mars; and the COSPAR mission categories that are used to assign planetary protection requirements. It also discussed questions of the scope of planetary protection policy, including the protection of scientific investigations and the protection of the planet itself. The committee held four meetings: a data-gathering meeting at the National Academies’ Keck Center in Washington, D.C.; a mini-workshop at Diversa Corporation in San Diego, California; a writing meeting at the SETI Institute in Mountain View, California; and a subcommittee writing session at the National Academies’ Beckman Center in Irvine, California. In addition, the committee held several teleconference calls to continue its deliberations and to discuss the draft report. In conducting its study, the committee considered input from several sources, including previous NRC reports as well as briefings and materials provided by NASA, the Jet Propulsion Laboratory, representatives from private industry, and the science and engineering community. In addition, the committee and meeting participants toured Diversa Corporation, a biotechnology company focused on cultivation-independent methods for recovery of and evolutionary studies on genes and biomolecules from the environment. One member of the committee visited a clean room for spacecraft assembly at the Jet Propulsion Laboratory to ascertain how planetary protection measures are implemented in practice, and two members visited associated research laboratories involved in advancing planetary protection techniques. Similarly, one committee member and staff visited the Lockheed Martin Astronautics Corporation to understand how the company has addressed
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Preventing the Forward Contamination of Mars planetary protection for Mars spacecraft and the lessons, challenges, and issues involved in implementing planetary protection measures during spacecraft assembly. ACKNOWLEDGMENTS The committee acknowledges the many individuals who participated in and provided presentations at meetings: Peter Annan, Sensors and Software, Canada; Amy Baker, Technical Administrative Services; David Beaty, Jet Propulsion Laboratory (JPL); William Boynton, Lunar and Planetary Laboratory; Karen Buxbaum, JPL; Cathy Chang, Diversa Corporation; Benton Clark, Lockheed Martin Astronautics; James Garvin, NASA Headquarters; Bruce Jakosky, University of Colorado, Boulder; Robert Koukol, JPL; Brad Lobitz, San Jose State University Foundation; Gerald McDonnell, Steris Corporation; Brian Muirhead, JPL; Kenneth Nealson, University of Southern California; Laura Newlin, JPL; Roger Phillips, Washington University, St. Louis; John Rummel, NASA Headquarters; Andrew Spry, Open University, United Kingdom; Pericles Stabekis, The Windermere Group; Andrew Steele, Carnegie Institution; Kasthuri Venkateswaran, JPL; and Norman Wainwright, Marine Biological Laboratory.
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Preventing the Forward Contamination of Mars Acknowledgment of Reviewers This report has been reviewed by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the National Research Council’s (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 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. We wish to thank the following individuals for their participation in the review of this report: Michelle Alfa, University of Manitoba, Philip R. Christensen, Arizona State University, Edward F. DeLong, Massachusetts Institute of Technology, Gerda Horneck, Institute of Aerospace Medicine, German Aerospace Center, Bruce M. Jakosky, University of Colorado, Jeffrey S. Kargel, U.S. Geological Survey, Tullis Onstott, Princeton University, David A. Stahl, University of Washington, Peter Staudhammer, Alfred E. Mann Institute for Biomedical Engineering, and James M. Tiedje, Michigan State University. 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 Mary Jane Osborn, University of Connecticut Health Center. Appointed by the National Research Council, she 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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Preventing the Forward Contamination of Mars Contents EXECUTIVE SUMMARY 1 1 INTRODUCTION 11 Policy Basis for Planetary Protection, 12 The Outer Space Treaty, 13 Protecting Science and Protecting Mars, 14 Past Delivery of Microorganisms to Mars, 16 Issues in and Organization of This Report, 20 References, 21 2 POLICIES AND PRACTICES IN PLANETARY PROTECTION 22 Planetary Protection Policy, 22 Implementation Requirements, 28 Maintaining Cleanliness During Launch, 33 Current Limitations of Standard Methods and Implementing Requirements, 33 References, 34 3 FUTURE MARS EXPLORATION: THE ROLLING WAVE 36 Increasing Complexity, Capability, and Creativity, 38 The Rolling Wave, 39 References, 40 4 ENVIRONMENTS ON MARS RELATIVE TO LIFE 41 Biogenic Materials, 42 Utilizable Energy, 42 Liquid Water, 43 A Catalog of Potentially Special Regions, 54 Techniques for Assessing the Distribution and State of Subsurface Water on Mars, 57 Measurements Needed to Identify Special Regions, 61
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Preventing the Forward Contamination of Mars Spacecraft Access and Special Regions, 63 Summary, 63 References, 64 5 EXPANDING OUR KNOWLEDGE OF THE LIMITS OF LIFE ON EARTH 69 Modern Views of Microbial Diversity, 69 Modern Technology and Microbial Ecology, 70 Organisms at the Limits of Life, 72 Life in Extreme Environments, 73 Probability of Growth on Mars, 84 Summary, 85 References, 86 6 ADVANCES IN TECHNOLOGIES FOR LIFE DETECTION AND BIOBURDEN REDUCTION 91 Examples of Methods for Assessing Total Viable Cell Count, 91 Examples of Methods for Estimating Biodiversity, 94 Methods for Reducing Bioburden, 99 Summary, 102 References, 103 7 ASSESSING NONLIVING CONTAMINANTS OF CONCERN 105 Types of Contaminants, 106 Determination of Acceptable Levels of Contamination, 108 Summary, 109 References, 109 8 A PATH FORWARD FOR PLANETARY PROTECTION IN THE 21st CENTURY 111 Expanding the Purpose of Planetary Protection: Safeguarding of Indigenous Life as Well as Protection of Mission Science?, 112 Programmatic Support, 112 Needed Research and Reconnaissance, 115 Transition to a New Approach, 117 Interim Requirements, 118 References, 123 9 TRANSITION PROCESS AND TIME LINE 124 Approach, 124 Implementation Time Line, 126 APPENDIXES A Biographical Sketches of Committee Members and Staff 131 B Recommendations from Two Previous NRC Reports on Forward Contamination 135 C Summary of Procedures Currently Used to Assess Bioburden in Spacecraft Assembly Clean Rooms and on Spacecraft 138 D History of Recommended Values for Probability of Growth 140 E Approaches to Bioburden Reduction for Lander Missions to Mars 141 F Ambiguities in Geomorphic Interpretation: Martian Gullies 144 G Spacecraft Propellant and By-Products as Potential Contaminants 148 H Acronyms and Abbreviations 152