Table of Contents
NASA ASTROBIOLOGY STRATEGY 2015
CONTRIBUTIONS
CONTENTS
EXECUTIVE SUMMARY
Identifying Abiotic Sources of Organic Compounds
Synthesis and Function of Macromolecules in the Origin of Life
Early Life and Increasing Complexity
Co-Evolution of Life and the Environment
Identifying, Exploring, and Characterizing Habitable Environments
Constructing Habitable Worlds
Conclusion
INTRODUCTION
UPDATES TO THE ROADMAP
SUMMARY
Astrobiology Strategic Plan: Updating the Astrobiology Roadmap
1 - IDENTIFYING ABIOTIC SOURCES OF ORGANICCOMPOUNDS
INTRODUCTION
1.1 Why is This Topic Important?
1.2 What Does This Research Entail?
1.3 Progress in the Last Ten Years
1.4 Areas of Research Within Abiotic Sources of Organic Compounds
I. What Were the Sources, Activities, and Fates of Organic Compounds on the Prebiotic Earth?
Key Research Questions about Molecules and Chemistry
II. What is the Role of the Environment in the Production of Organic Molecules?
Key Research Questions about the Production of Organics
III. What is the Role of the Environment on the Stability and Accumulation of Organic Molecules?
Key Research Questions about the Stability and Accumulation of Organics
IV. What Constraints Can the Rock Record Place on the Environments and Abiotic Reactions of the Early Earth?
Key Research Questions about the Environment of Early Earth
1.5 Challenges for the Next Ten Years
FURTHER READING
2 - SYNTHESIS AND FUNCTION OF MACROMOLECULES IN THE ORIGIN OF LIFE
INTRODUCTION
2.1 Why is This Topic Important?
2.2 What Does This Research Entail?
Overcoming Kinetic and Thermodynamic Hurdles
The Role of Catalysts
The Selection of Homochirality
The Role of the Planetary Environment
Concentration of Reactants
Pathways of Evolution
The Question of Polymer Function
Cooperation
2.3 Progress in the Last Ten Years
Macromolecule Formation
Prebiotic Models for Macromolecular Synthesis and Replication
Macromolecular Function
2.4 Areas of Research Within Synthesis and Function of Macromolecules in the Origin of Life
I. Paths to Today’s DNA/RNA/Protein-Dominated World
A. Big Picture Questions
B. Key Research Questions
2.5 Challenges for the Next Ten Years
FURTHER READING
3 - EARLY LIFE AND INCREASING COMPLEXITY
INTRODUCTION
3.1 Why is This Topic Important?
3.2 What Does This Research Entail?
Life’s Origin
The Evolution of Complexity
Universal Traits of Life
3.3 Progress in the Last Ten Years
3.4 Areas of Research Within Early Life and Increasing Complexity
I. Origin and Dynamics of Evolutionary Processes in Living Systems: Theoretical Considerations
Key Research Questions about Origins and Dynamics of Evolutionary Processes
II. Fundamental Innovations in Earliest Life
Key Research Questions about Innovations in Earliest Life
III. Genomic, Metabolic, and Ecological Attributes of Life at the Root of the Evolutionary Tree (LUCA)
Key Research Questions about Attributes of LUCA
IV. Dynamics of the Subsequent Evolution of Life
Intrinsic Factors
Extrinsic Factors
Composite Events: Intrinsic plus Extrinsic Factors
Key Research Questions about the Dynamics of the Subsequent Evolution of Life
V. Common Attributes of Living Systems on Earth
Key Research Questions about the Common Attributes of Living Systems
FURTHER READING
4 - CO-EVOLUTION OF LIFE AND THE PHYSICAL ENVIRONMENT
INTRODUCTION
4.1 Why is This Topic Important?
4.2 What Does This Research Entail?
4.3 Progress in the Last Ten Years
4.4 Areas of Research Within Co-Evolution of Life and the Physical Environment
I. How Does the Story of Earth—Its Past, Present, and Future—Inform Us about How the Climates, Atmospheric Compositions, Interiors, and Biospheres of Planets Can Co-Evolve?
Key Research Questions
II. How Do the Interactions between Life and Its Local Environment Inform Our Understanding of Biological and Geochemical Co-Evolutionary Dynamics?
Key Research Questions
III. How Does Our Ignorance About Microbial Life on Earth Hinder Our Understanding of the Limits to Life?
Key Research Questions
4.5 Challenges for the Next Ten Years
How do the different worlds of the past, present, and future Earth inform our understanding of exoplanets?
How can we better understand the constraints on the timing and tempo of surface evolution and processes?
What is the fidelity of proxies of biology and environment over long and complex geologic histories?
How can biological data and geologic data be integrated through evolutionary time?
How can we develop new approaches or modifications of current approaches to enrich and ultimately isolate organisms currently known only by their DNA sequences?
What are the methodological challenges coordinating and synthesizing in silico data?
FURTHER READING
5 - IDENTIFYING, EXPLORING, AND CHARACTERIZING ENVIRONMENTS FOR HABITABILITY AND BIOSIGNATURES
INTRODUCTION
5.1 Why is This Topic Important?
5.2 What Does This Research Entail?
5.3 Progress in the Last Ten Years
Exoplanets
Icy Bodies
Mars
Earth
Biosignatures
5.4 Areas of Research Within Identifying, Exploring, and Characterizing Environments for Habitability and Biosignatures
I. How Can We Assess Habitability on Different Scales?
Key Research Questions about Assessing Habitability
II. How Can We Enhance the Utility of Biosignatures to Search for Life in the Solar System and Beyond?
Key Research Questions about Biosignatures
III. How Can We Identify Habitable Environments and Search for Life within the Solar System?
Earth’s Analog Environments
Mars
Icy Worlds in the Solar System
IV. How Can We Identify Habitable Planets and Search for Life beyond the Solar System
Characterizing Potentially Habitable Exoplanets
Searching for Life on Exoplanets
Key Research Questions about Exoplanets
CURRENT TECHNIQUES AND STRATEGIES FOR LIFE DETECTION
Remote Detection
Direct Detection
FURTHER READING
6 - CONSTRUCTING HABITABLE WORLDS
INTRODUCTION
6.1 What Makes an Environment Habitable?
6.2 Why is This Topic Important?
6.3 What Does This Research Entail?
6.4 Progress in the Last Ten Years
Identifying Habitable Zones
Revealing the Formation of Planetary Systems
The Important Role of Small Bodies in Forming Habitable Worlds
Understanding the Diversity of Habitable Worlds
Achievements in Earth System Science
6.5 Areas of Research Within Constructing Habitable Worlds
I. What are the Fundamental Ingredients and Processes That Define a Habitable Environment?
Key Research Questions for Ingredients and Processes
II. What are the Exogenic Factors in the Formation of a Habitable Planet?
Key Research Questions for Exogenic Factors
III. What Does Earth Tell Us about General Properties of Habitability (and What is Missing)?
Key Research Questions for General Properties of Habitability on Earth
IV. What Are the Processes on Other Types of Planets That Could Create Habitable Niches?
Key Research Questions for Habitability on Other Planets
V. How Does Habitability Change Through Time?
Key Research Questions for Changes in Habitability through Time
6.6 Questions and Challenges for the Next Ten Years
FURTHER READING
7 - CHALLENGES AND OPPORTUNITIES IN ASTROBIOLOGY
INTRODUCTION
7.1 Where Are We Now?
I. What is Life?
Key Research Questions for Defining Life
II. How Will We Know When We Have Found Life?
Key Research Questions for Knowing When We Have Found Life
III. Can We Draw the Boundary Between Prebiotic Chemistry and Life?
Key Research Questions for the Possible Boundary between Prebiotic Chemistry and Life
IV. How Can We Account for “Weird Life” That May Have Alternative Biochemistry or Alternative Habitability Constraints?
Key Research Questions for Potential “Weird Life”
V. How Should Astrobiology Approach Perturbations to Planetary Biospheres by Technological Civilizations on Earth and Elsewhere in the Universe?
Key Research Questions for Astrobiology’s Approach to Perturbations to Planetary Biospheres by Technological Civilization
VI. How Does Astrobiology Relate to Other Fields, and How Does It Operate in the Context of Those Other Efforts?
Key Research Questions for Astrobiology’s Relationship with Other Fields
7.2 Confronting These Challenges Creates Additional Benefits
FURTHER READING
APPENDICES
BEYOND NATURAL SCIENCES: HUMANITIES AND SOCIAL SCIENCE CONTRIBUTIONS TO ASTROBIOLOGY
INTRODUCTION
A. What Is the Role for Epistemology in Astrobiology?
B. What Is the Role for Social Science in Astrobiology?
C. What Is the Role for Ethics in Astrobiology?
D. What Is the Role for History in Astrobiology?
E. What Is the Role for Law in Astrobiology?
F. What is the Role for Communications in Astrobiology?
G. What Is the Role for Astrobiology in Education?
THINGS TO WORK ON IN THE COMING TEN YEARS
FURTHER READING
GLOSSARY
REFERENCES
INDEX
