Searching for
LIFE
across SPACE
and TIME
PROCEEDINGS OF A WORKSHOP
Joseph R. Schmitt, Rapporteur
Space Studies Board
Division on Engineering and Physical Sciences
THE NATIONAL ACADEMIES PRESS
Washington, DC
www.nap.edu
THE NATIONAL ACADEMIES PRESS 500 Fifth Street, NW Washington, DC 20001
This study is based on work supported by the Contract NNH11CD57B between the National Academy of Sciences and the National Aeronautics and Space Administration. Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any organization or agency that provided support for the project.
International Standard Book Number-13: 978-0-309-46394-2
International Standard Book Number-10: 0-309-46394-7
Digital Object Identifier: https://doi.org/10.17226/24860
Copies of this publication are available free of charge from:
Space Studies Board
The National Academies of Sciences, Engineering, and Medicine
500 Fifth Street, NW
Washington, DC 20001
Additional copies of this publication are available from the National Academies Press, 500 Fifth Street, NW, Keck 360, Washington, DC 20001; (800) 624-6242 or (202) 334-3313; http://www.nap.edu.
Copyright 2017 by the National Academy of Sciences. All rights reserved.
Printed in the United States of America
Suggested citation: National Academies of Sciences, Engineering, and Medicine. 2017. Searching for Life across Space and Time: Proceedings of a Workshop. Washington, DC: The National Academies Press. https://doi.org/10.17226/24860.
The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, nongovernmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president.
The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. C. D. Mote, Jr., is president.
The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president.
The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine.
Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org.
Consensus Study Reports published by the National Academies of Sciences, Engineering, and Medicine document the evidence-based consensus on the study’s statement of task by an authoring committee of experts. Reports typically include findings, conclusions, and recommendations based on information gathered by the committee and the committee’s deliberations. Each report has been subjected to a rigorous and independent peer-review process and it represents the position of the National Academies on the statement of task.
Proceedings published by the National Academies of Sciences, Engineering, and Medicine chronicle the presentations and discussions at a workshop, symposium, or other event convened by the National Academies. The statements and opinions contained in proceedings are those of the participants and are not endorsed by other participants, the planning committee, or the National Academies.
For information about other products and activities of the National Academies, please visit www.nationalacademies.org/about/whatwedo.
ORGANIZING COMMITTEE ON SEARCHING FOR LIFE ACROSS SPACE AND TIME: A WORKSHOP
JAMES F. KASTING, Pennsylvania State University, Chair
WILLIAM BAINS, Massachusetts Institute of Technology, University of Cambridge
TANJA BOSAK, Massachusetts Institute of Technology
IRENE A. CHEN, University of California, Santa Barbara
KEVIN P. HAND, Jet Propulsion Laboratory
CHRISTOPHER H. HOUSE, Pennsylvania State University
VICTORIA MEADOWS, University of Washington
PHILIP M. NECHES, NAE,1 Teradata Corporation
NILTON O. RENNO, University of Michigan
DIMITAR SASSELOV, Harvard-Smithsonian Center for Astrophysics
GARY RUVKUN, NAS2/NAM3, Harvard Medical School
MARK H. THIEMENS, NAS, University of California, San Diego
NITA SAHAI, The University of Akron
MARGARET TURNBALL, SETI Institute
Staff
DAVID H. SMITH, Study Director
MIA BROWN, Research Associate
KATIE DAUD, Research Associate
DIONNA WILLIAMS, Program Coordinator
SARAH PEACOCK, Lloyd V. Berkner Space Policy Intern
CHERIE ACHILLES, Lloyd V. Berkner Space Policy Intern
JOSEPH R. SCHMITT, Christine Mirzayan Science and Technology Policy Graduate Fellow
MICHAEL H. MOLONEY, Director
___________________
1 National Academy of Engineering.
2 National Academy of Sciences.
3 National Academy of Medicine.
SPACE STUDIES BOARD
FIONA HARRISON, NAS,1 California Institute of Technology, Chair
ROBERT D. BRAUN, NAE,2 University of Colorado, Boulder, Vice Chair
DAVID N. SPERGEL, NAS, Princeton University and Center for Computational Astrophysics at the Simons Foundation, Vice Chair
JAMES G. ANDERSON, NAS, Harvard University
JEFF M. BINGHAM, Consultant
JAY C. BUCKEY, Geisel School of Medicine at Dartmouth College
MARY LYNNE DITTMAR, Dittmar Associates
JOSEPH FULLER, JR., Futron Corporation
THOMAS R. GAVIN, California Institute of Technology
SARAH GIBSON, National Center for Atmospheric Research
WESLEY T. HUNTRESS, Carnegie Institution of Washington
ANTHONY C. JANETOS, Boston University
CHRYSSA KOUVELIOTOU, NAS, George Washington University
DENNIS P. LETTENMAIER, NAE, University of California, Los Angeles
ROSALY M. LOPES, Jet Propulsion Laboratory
DAVID J. McCOMAS, Princeton University
LARRY PAXTON, Johns Hopkins University, Applied Physics Laboratory
SAUL PERLMUTTER, NAS, Lawrence Berkeley National Laboratory
ELIOT QUATAERT, University of California, Berkeley
BARBARA SHERWOOD LOLLAR, University of Toronto
HARLAN E. SPENCE, University of New Hampshire
MARK H. THIEMENS, NAS, University of California, San Diego
MEENAKSHI WADHWA, Arizona State University
Staff
MICHAEL H. MOLONEY, Director
CARMELA J. CHAMBERLAIN, Administrative Coordinator
TANJA PILZAK, Manager, Program Operations
CELESTE A. NAYLOR, Information Management Associate
MARGARET KNEMEYER, Financial Officer
SU LIU, Financial Assistant
___________________
1 National Academy of Sciences.
2 National Academy of Engineering.
Acknowledgment of Reviewers
This Proceedings of a Workshop was reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise. The purpose of this independent review is to provide candid and critical comments that will assist the National Academies of Sciences, Engineering, and Medicine in making each published proceedings as sound as possible and to ensure that it meets the institutional standards for quality, objectivity, evidence, and responsiveness to the charge. The review comments and draft manuscript remain confidential to protect the integrity of the process.
We thank the following individuals for their review of this proceedings:
Courtney Dressing, California Institute of Technology,
Marilyn Fogel, University of California, Riverside,
Sarah Hörst, Johns Hopkins University,
David Paige, University of California, Los Angeles, and
David Spergel, NAS,1 Princeton University.
Although the reviewers listed above provided many constructive comments and suggestions, they were not asked to endorse the content of the proceedings nor did they see the final draft before its release. The review of this proceedings was overseen by Charles F. Kennel, NAS, University of California, San Diego. He was responsible for making certain that an independent examination of this proceedings was carried out in accordance with standards of the National Academies and that all review comments were carefully considered. Responsibility for the final content rests entirely with the rapporteur(s) and the National Academies.
___________________
1 National Academy of Sciences.
This page intentionally left blank.
Contents
How Likely Is It that Life Exists Beyond Earth?
The Limits of Life and Its Interaction with the Environment
Is Life a Cosmic Imperative: How Would Thermodynamics Force Life into Existence?
2 HABITABLE ENVIRONMENTS IN THE SOLAR SYSTEM
Habitable Environments of Ancient Mars: Deciphering the Rock Record
On the Habitability of Ocean Worlds
Planning for the Exploration of Mars and Ocean Worlds
Extrasolar Biosignatures: Developing a Comprehensive Framework for Biosignature Recognition
Extrasolar Biosignatures: Thinking Outside the Box
Technology Needs to Discover Earth 2.0
Prospects for Ground-Based Characterization of Proxima Centauri B
Life Detection: 40 Years After Viking
Looking for Life as We Know It on Other Planets
Signatures of Life as We Don’t Know It
Plume Fly-Through Missions: Detecting Life In Situ at Several Kilometers per Second
6 FUTURE DIRECTIONS: REPORT OF BREAKOUT GROUPS
In Situ Detection of Life as We Know It
In Situ Detection of Life as We Don’t Know It
Remote Detection of Life as We Know It
Remote Detection of Life as We Don’t Know It
Summary of Chapter 1: Setting the Stage
Summary of Chapter 2: Habitable Environments in the Solar System
Summary of Chapter 3: Exoplanets
Summary of Chapter 4: Life Detection Techniques