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An Astrobiology Strategy for the Exploration of Mars An Astrobiology Strategy for the EXPLORATION of MARS Committee on an Astrobiology Strategy for the Exploration of Mars Space Studies Board Division on Engineering and Physical Sciences Board on Life Sciences Division on Earth and Life Studies NATIONAL RESEARCH COUNCIL OF THE NATIONAL ACADEMIES THE NATIONAL ACADEMIES PRESS Washington, D.C. www.nap.edu
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An Astrobiology Strategy for the Exploration 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-13: 978-0-309-10851-5 International Standard Book Number-10: 0-309-10851-9 Cover design by Penny E. Margolskee. Images courtesy of National Aeronautics and Space Administration/Jet Propulsion Laboratory. 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 for purchase 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 2007 by the National Academy of Sciences. All rights reserved. Printed in the United States of America
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An Astrobiology Strategy for the Exploration 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. Charles M. Vest 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. Charles M. Vest are chair and vice chair, respectively, of the National Research Council. www.national-academies.org
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An Astrobiology Strategy for the Exploration of Mars OTHER REPORTS OF THE SPACE STUDIES BOARD Building a Better NASA Workforce: Meeting the Workforce Needs for the National Vision for Space Exploration (2007) Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond (2007) Exploring Organic Environments in the Solar System (SSB with the Board on Chemical Sciences and Technology, 2007) A Performance Assessment of NASA’s Astrophysics Program (SSB with the Board on Physics and Astronomy, 2007) An Assessment of Balance in NASA’s Science Programs (2006) Assessment of NASA’s Mars Architecture 2007-2016 (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: Interim Report (SSB with the Aeronautics and Space Engineering Board [ASEB], 2006) Review of NASA’s 2006 Draft Science Plan: Letter Report (2006) The Scientific Context for Exploration of the Moon—Interim Report (2006) Space Radiation Hazards and the Vision for Space Exploration (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) 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 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) 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) email@example.com www.nationalacademies.org/ssb/ssb.html NOTE: Listed according to year of approval for release, which in some cases precedes the year of publication.
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An Astrobiology Strategy for the Exploration of Mars COMMITTEE ON AN ASTROBIOLOGY STRATEGY FOR THE EXPLORATION OF MARS BRUCE M. JAKOSKY, University of Colorado, Chair JAN P. AMEND, Washington University in St. Louis WILLIAM M. BERELSON, University of Southern California RUTH E. BLAKE, Yale University SUSAN L. BRANTLEY, Pennsylvania State University MICHAEL H. CARR, U.S. Geological Survey (retired) JAMES K. FREDRICKSON, Pacific Northwest Research Laboratory ANTHONY D. KEEFE, Archemix Corporation MARTIN KELLER, Oak Ridge National Laboratory HARRY Y. McSWEEN, University of Tennessee KENNETH H. NEALSON, University of Southern California BARBARA SHERWOOD-LOLLAR, University of Toronto ANDREW STEELE, Carnegie Institution of Washington ROGER E. SUMMONS, Massachusetts Institute of Technology MEENAKSHI WADHWA, Arizona State University Staff DAVID H. SMITH, Study Director ROBERT L. RIEMER, Senior Program Officer RODNEY N. HOWARD, Senior Project Assistant CATHERINE A. GRUBER, Assistant Editor ANGELA BABER, Research Assistant EMILY McNEIL, Research Assistant
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An Astrobiology Strategy for the Exploration of Mars 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 BERRIEN MOORE III, University of New Hampshire KENNETH H. NEALSON, University of Southern California NORMAN P. NEUREITER, American Association for the Advancement of Science SUZANNE OPARIL, University of Alabama, Birmingham JAMES PAWELCZYK, Pennsylvania State University RONALD F. PROBSTEIN, Massachusetts Institute of Technology HARVEY D. TANANBAUM, Harvard-Smithsonian Center for Astrophysics 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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An Astrobiology Strategy for the Exploration of Mars BOARD ON LIFE SCIENCES KEITH YAMAMOTO, University of California, San Francisco, Chair ANN M. ARVIN, Stanford University School of Medicine JEFFREY L. BENNETZEN, University of Georgia RUTH BERKELMAN, Emory University DEBORAH BLUM, University of Wisconsin R. ALTA CHARO, University of Wisconsin JEFFREY L. DANGL, University of North Carolina PAUL R. EHRLICH, Stanford University MARK D. FITZSIMMONS, John D. and Catherine T. MacArthur Foundation JO HANDELSMAN, University of Wisconsin ED HARLOW, Harvard Medical School KENNETH H. KELLER, University of Minnesota RANDALL MURCH, Virginia Polytechnic Institute and State University GREGORY A. PETSKO, Brandeis University MURIEL E. POSTON, Skidmore College JAMES REICHMAN, University of California, Santa Barbara MARC T. TESSIER-LAVIGNE, Genentech, Inc. JAMES TIEDJE, Michigan State University TERRY L. YATES, University of New Mexico FRAN SHARPLES, Director
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An Astrobiology Strategy for the Exploration of Mars Preface Scientific strategies for the exploration of Mars have been defined in recent years by various groups, including both the National Research Council (NRC) and NASA. The findings and recommendations of the Space Studies Board’s reports Assessment of Mars Science and Mission Priorities (2003) and New Frontiers in the Solar System: An Integrated Exploration Strategy (2003) are broadly consistent with the priorities outlined in the report of NASA’s Mars Exploration Program Analysis Group (MEPAG), Scientific Goals, Objectives, Investigations, and Priorities: 2004. Although all three reports agreed that highest priority should be assigned to determining if living organisms ever arose on Mars, their timing was such that new insights arising from the biological sciences (e.g., insights based on studies of organisms that thrive on Earth under extreme conditions and on developing techniques arising from molecular biology and biotechnology) did not play a prominent role in their authors’ deliberations. Rather, all three groups considered the search for life in the context of the origin and evolution of the martian environment. Now, with the benefit of several additional years of maturation, the time is right to attempt a new synthesis of ideas on the search for life on Mars that integrates input from both the life sciences and the environmental sciences communities. Indeed, Signs of Life (2002), the report of a Space Studies Board workshop, demonstrated that both new evidence and new techniques are available to assist the search for life on Mars, and the report advocated furthering the research on and development of emerging technologies and incorporating both emerging and developed technologies into the astrobiological search for life. Although NASA’s MEPAG has been particularly active in the last few years in defining the key environmental issues relating to the search for life on Mars, NASA’s most recent end-to-end strategy for the detection of martian life, An Exobiological Strategy for Mars Exploration, was published in 1995. The corresponding European Space Agency strategy, Exobiology in the Solar System and the Search for Life on Mars, was published in 1999. Clearly, the various ideas and concepts encompassing the biological and environmental perspectives relevant to the search for martian life developed in a diversity of reports published between 1995 and 2004 were ripe for integration. The Committee on the Origins and Evolution of Life (COEL)—a joint undertaking of the NRC’s Space Studies Board and Board on Life Sciences charged with maintaining oversight on issues relating to astrobiology—discussed such a possibility extensively during several of its meetings in 2004 and in early 2005 persuaded NASA officials that the time was right for a study integrating the various Mars exploration strategies and life-detection concepts into a single, coherent picture. As a result of COEL’s activities and other factors, Mary L. Cleave, then NASA’s associate administrator for the Science Mission Directorate, sent a letter to Lennard A. Fisk, chair of the Space Studies Board, on September 13,
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An Astrobiology Strategy for the Exploration of Mars 2005, requesting assistance “in developing an up-to-date integrated astrobiology strategy for Mars exploration that brings together all the threads of this diverse topic into a single source for science mission planning ….” Dr. Cleave’s request was passed back to COEL and discussed extensively during a meeting held at the Southwest Research Institute in Boulder, Colorado, on October 3-5, 2005. As a result of COEL’s discussions and deliberations, a plan of action was developed that resulted in the formal appointment in January 2006 of the ad hoc Committee on an Astrobiology Strategy for the Exploration of Mars. The committee met for the first time at the National Academies’ Beckman Center in Irvine, California, on January 23-25, 2006. Work continued at meetings held at the National Academies’ Keck Center in Washington, D.C. (May 10-12), the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder, Colorado (September 13-15), and the National Academies’ J. Erik Jonsson Center in Woods Hole, Massachusetts (November 8-10). A draft report was completed in early December and sent to external review in mid-December. A new draft responding to the reviewers’ comments was completed in late January 2007, and the report was approved for release in May 2007. 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: Marc Allen (NASA, Science Mission Directorate), Mark Allen (NASA, JPL), Ariel Anbar (Arizona State University), Jillian Banfield (University of California, Berkeley), John Baross (University of Washington), David Beatty (NASA, JPL), Luann Becker (University of California, Santa Barbara), Luther Beegle (NASA, JPL), Klaus Biemann (Massachusetts Institute of Technology), David Catling (University of Bristol), Barbara Cohen (University of New Mexico), David DesMarais (NASA, Ames Research Center), Christopher M. Fedo (University of Tennessee), Matthew Golombeck (NASA, JPL), Ronald Greeley (Arizona State University), Andrew Knoll (Harvard University), Paul R. Mahaffy (NASA, Goddard Space Flight Center), Michael Malin (Malin Space Science Systems), Michael Meyer (NASA, Science Mission Directorate), Jack F. Mustard (Brown University), Tullis C. Onstott (Princeton University), Carl Pilcher (NASA Astrobiology Institute), Susannah Porter (University of California, Santa Barbara), John Rummel (NASA, Science Mission Directorate), Bruce Runnegar (NASA Astrobiology Institute), Alan Treiman (Lunar and Planetary Institute), Ashwin R. Vasavada (NASA, JPL), Frances Westall (Centre de Biophysique Moleculaire, CNRS), and Richard W. Zurek (NASA, JPL). 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: Robert D. Braun (Georgia Institute of Technology), Charles S. Cockell (The Open University), John Kerridge (University of California, San Diego), Alfred S. McEwen (University of Arizona), Hiroshi Ohmoto (Pennsylvania State University), Norman R. Pace (University of Colorado), and Dawn Y. Sumner (University of California, Davis). 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 Norman H. Sleep (Stanford University). 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.
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An Astrobiology Strategy for the Exploration of Mars Contents EXECUTIVE SUMMARY 3 1 INTRODUCTION 11 Outline of Approach, 13 References, 16 2 THE PRESENT STATE OF KNOWLEDGE ABOUT MARS AND POSSIBLE LIFE 19 Environmental Requirements for Life, 19 Does Mars Meet Habitability Requirements?, 20 Lessons Learned from Prior Investigations About Mars and Possible Life, 27 References, 35 3 BIOSIGNATURES AND ABIOTIC CHEMISTRY 41 Abiotic Chemistry, 42 Terran Biosignatures and Potential Martian Biosignatures, 43 References, 52 4 CHARACTERISTICS OF SITES FOR ASTROBIOLOGICAL INVESTIGATION 57 The Search for Signs of Prebiotic Chemistry, 57 The Search for Past Life, 58 Sites and Samples for Recent Life, 62 Summary, 64 References, 64 5 METHODOLOGIES FOR ADVANCING ASTROBIOLOGY 69 Orbital Measurements at Global and Regional Scales, 69 Geological and Environmental Context at Local Sites, 70 In Situ Analyses Related to Life Detection, 71 Mars Meteorite Collection and Analysis, 73
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An Astrobiology Strategy for the Exploration of Mars Analyses of Returned Samples and Strategies for Maximizing Astrobiological Potential, 75 Studies of Earth Analogs for Environments on Mars That May Harbor Life, 77 Technical Developments, 80 References, 81 6 ASTROBIOLOGICAL ASSESSMENT OF CURRENT MARS MISSION ARCHITECTURE 85 Active Missions, 85 Missions in Development and Planning, 88 References, 91 7 PLANETARY PROTECTION FOR MARS MISSIONS 95 COSPAR and NASA Policies, 95 Special Regions, 96 Technology for Planetary Protection, 96 References, 97 8 FINDINGS AND RECOMMENDATIONS 99 The Search for Life on Mars, 99 Characteristics of Potential Target Sites, 102 Biosignatures, 103 Exploration Methodologies and Instrumentation, 104 Maximization of Science, 105 References, 107 APPENDIXES A Martian Features Mentioned in Text 111 B Glossary 113 C Objectives for Developing a Further Understanding of Biosignatures 117