Astrobiology

Cover
Acknowledgments
About the Companion Website
1 Astrobiology
1.1 Introductory Remarks
1.2 The Major Questions of Astrobiology and the Content of the Textbook
1.3 Some Other Features of the Textbook
1.4 A Brief History of Astrobiology
1.5 Conclusions
Bibliography
2 What Is Life?
2.1 The Concept of “Life”
2.2 What Is Life? The Historical Perspective
2.3 Spontaneous Generation
2.4 More Modern Concepts
2.5 Schrödinger and Life
2.6 Life as a Dissipative Process
2.7 Life: Just a Human Definition?
2.8 Does It Matter Anyway?
2.9 Conclusions
Bibliography
3 Matter and Life
3.1 Matter and Life
3.2 Life Is Made of “Ordinary” Matter
3.3 The Atomic Nucleus
3.4 Electrons, Atoms, and Ions
3.5 Types of Bonding in Matter
3.6 Ionic Bonding
3.7 Covalent Bonding
3.8 Metallic Bonding
3.9 Van der Waals Interactions
3.10 Hydrogen Bonding
3.11 An Astrobiological Perspective
3.12 The Equation of State Describes the Relationship Between Different Types of Matter
3.13 Other States of Matter
3.14 The Interaction Between Matter and Light
3.15 Conclusions
Bibliography
4 The Molecular Structure of Life
4.1 Building Life
4.2 The Essential Elements: CHNOPS
4.3 Carbon Is Versatile
4.4 The Chains of Life
4.5 Proteins
4.6 Chirality
4.7 Carbohydrates (Sugars)
4.8 Lipids
4.9 The Nucleic Acids
4.10 The Solvent of Life
4.11 Alternative Chemistries
4.12 The Structure of Life and Habitability
4.13 Conclusions
Bibliography
5 The Cellular Structure of Life
5.1 From Molecules to Cells
5.2 Types of Cells
5.3 Shapes of Cells
5.4 The Structure of Cells
5.5 The Structure of Cellular Membranes
5.6 The Information Storage System of Life
5.7 Eukaryotic Cells
5.8 The Reproduction of Cells
5.9 Why Did Sexual Reproduction Evolve?
5.10 The Growth of Populations of Cells
5.11 Moving and Communicating
5.12 Viruses
5.13 Prions
5.14 Conclusions
Bibliography
6 Energy for Life
6.1 Energy and Astrobiology
6.2 Life and Energy
6.3 The Central Role of Adenosine Triphosphate
6.4 Chemiosmosis and Energy Acquisition
6.5 What Types of Electron Donors and Acceptors Can Be Used?
6.6 Aerobic Respiration
6.7 Anaerobic Respiration
6.8 Fermentation
6.9 Chemoautotrophs: Changing the Electron Donor
6.10 Energy from Light: Photosynthesis
6.11 Oxygenic Photosynthesis
6.12 Anoxygenic Photosynthesis
6.13 Rhodopsins and Photosynthesis
6.14 Evolution of Photosynthesis
6.15 Global Biogeochemical Cycles
6.16 Microbial Mats – Energy-Driven Zonation in Life
6.17 The Thermodynamics of Energy Acquisition and Life
6.18 Energy and Life in Extremes
6.19 Conclusions
Bibliography
7 The Limits of Life
7.1 The Limits of Life
7.2 The Importance of the Limits of Life for Astrobiology
7.3 The Most Extreme Conditions are Dominated by Microbes
7.4 Life at High Temperatures
7.5 Life at Low Temperatures
7.6 Salt-Loving Organisms
7.7 pH Extremes
7.8 Life Under High Pressure
7.9 Tolerance to High Radiation
7.10 Life in Toxic Brews
7.11 Rocks as a Habitat
7.12 Polyextremophiles – Dealing with Multiple Extremes
7.13 Life Underground
7.14 Dormancy in Extreme Conditions
7.15 Eukaryotic Extremophiles
7.16 Are There Other Biospheres with Different Limits?
7.17 The Limits of Life: Habitability Revisited
7.18 Conclusions
Bibliography
8 The Tree of Life
8.1 A Vast Quantity of Life
8.2 Evolution and a “Tree of Life”
8.3 Classifying Organisms
8.4 The Tree of Life and Some Definitions
8.5 Problems with Classification: Homology and Analogy
8.6 Building a Phylogenetic Tree Using Genetic Material
8.7 Types of Phylogenetic Trees
8.8 A Modern View of the Tree of Life
8.9 Using Phylogenetic Trees to Test Hypotheses
8.10 Complications in Building Trees
8.11 Origin of Eukaryotes
8.12 The Last Universal Common Ancestor
8.13 Multiple Origins of Life?
8.14 Alien Life
8.15 Conclusions
Bibliography
9 The Universe, the Solar System, and the Elements of Life
9.1 Our Cosmic Situation
9.2 In the Beginning: The Formation of the Universe
9.3 Stellar Evolution: Low-Mass Stars
9.4 Stellar Evolution: High-Mass Stars
9.5 The Elements of Life
9.6 The Hertzsprung–Russell Diagram
9.7 The Sun Is a Blackbody
9.8 The Formation of Planets
9.9 Types of Objects in Our Solar System
9.10 Meteorites and Their Classification
9.11 Laws Governing the Motion of Planetary Bodies
9.12 Conclusions
Bibliography
10 Astrochemistry: Carbon in Space
10.1 Astrochemistry: Carbon Molecules in Space
10.2 Observing Organics
10.3 In the Beginning
10.4 Different Environments for Chemistry
10.5 How Do Chemical Reactions Occur?
10.6 Forming Carbon Compounds
10.7 Formation of Water
10.8 Interstellar Grains
10.9 Polycyclic Aromatic Hydrocarbons
10.10 Even More Carbon Diversity
10.11 Comets and Organic Molecules
10.12 The Origin of Chirality
10.13 Laboratory Experiments
10.14 Observing Organic Molecules
10.15 Conclusions
Bibliography
11 Early Earth: The First Billion Years
11.1 The First Billion Years of Earth
11.2 Earth Forms and Differentiates
11.3 The Formation of the Moon
11.4 The Early Oceans
11.5 The Early Crust
11.6 The Early Atmosphere
11.7 The Temperature of Early Earth
11.8 The Late Heavy Bombardment
11.9 Implications of the Early Environment for Life
11.10 Conclusions
Bibliography
12 The Origin of Life
12.1 The Origin of Life
12.2 The Synthesis of Organic Compounds on Earth
12.3 Delivery from the Extraterrestrial Environment
12.4 The RNA World
12.5 Early Cells
12.6 Where Did the Origin of Life Occur?
12.7 A Cold Origin of Life?
12.8 The Whole Earth as a Reactor?
12.9 Conclusions
Bibliography
13 Early Life on Earth
13.1 Early Life on Earth
13.2 Early Life – Metabolisms and Possibilities
13.3 Isotopic Fractionation
13.4 Measuring the Isotope Fractionation: The Delta Notation
13.5 Sulfur Isotope Fractionation
13.6 Using Isotopes to Look for Ancient Life
13.7 Morphological Evidence for Life
13.8 Biomarkers
13.9 Contamination Is a Problem
13.10 Instruments Used to Look for Life
13.11 A Brief Summary
13.12 The Search for Extraterrestrial Life
13.13 Conclusions
Bibliography
14 The Geology of a Habitable World
14.1 The Geological History of Earth: A Habitable World
14.2 Minerals and Glasses
14.3 Types of Rocks
14.4 The Rock Cycle
14.5 The Composition of Earth
14.6 Plate Tectonics
14.7 Dating the Age of the Earth (and Other Planetary Bodies)
14.8 Age-Dating Rocks
14.9 Geological Timescales
14.10 The Major Classifications of Geological Time
14.11 Some Geological Times and Biological Changes
14.12 Conclusions
Bibliography
15 The Co-evolution of Life and a Planet: The Rise of Oxygen
15.1 Dramatic Changes on Earth
15.2 Measuring Oxygen Through Time
15.3 It Was Not a Simple Rise
15.4 Summarizing the Evidence for the GOE
15.5 The Source of Oxygen
15.6 Sinks for Oxygen
15.7 Why Did Atmospheric Oxygen Concentrations Rise?
15.8 Snowball Earth Episodes
15.9 Other Biological Consequences of the Rise of Oxygen
15.10 Oxygen and the Rise of Animals
15.11 Oxygen and the Rise of Intelligence
15.12 Periods of High Oxygen
15.13 Conclusions
Bibliography
16 Mass Extinctions
16.1 Extinctions
16.2 What Is Extinction?
16.3 Five Major Mass Extinctions
16.4 Other Extinctions in Earth History
16.5 Causes of Mass Extinction
16.6 The End-Cretaceous Extinction
16.7 The Other Four Big Extinctions of the Phanerozoic
16.8 Do Microorganisms Go Extinct?
16.9 Recovery from Extinction
16.10 Can We Avoid Extinction?
16.11 The Sixth Mass Extinction?
16.12 Conclusions
Bibliography
17 The Habitability of Planetary Bodies
17.1 What Is “Habitability”?
17.2 The Habitable Zone
17.3 Maintaining Temperature Conditions on a Planet Suitable for Water and Life
17.4 Plate Tectonics and Habitability
17.5 Does the Moon Play a Role in Habitability?
17.6 Other Planetary Factors that Influence Habitability
17.7 Surface Liquid Water, Habitability, and Intelligence
17.8 Habitable Environments Need Not Always Contain Life
17.9 Worlds More Habitable than Earth?
17.10 The Anthropic Principle and Habitability
17.11 The Fate of Earth
17.12 The Galactic Habitable Zone
17.13 The Right Galaxy?
17.14 Conclusions
Bibliography
18 The Astrobiology of Mars
18.1 Mars and Astrobiology
18.2 Martian Geological History: A Very Brief Summary
18.3 The Environmental Deterioration of Mars
18.4 Missions to Mars
18.5 Mars and Life
18.6 Trajectories of Martian Habitability
18.7 The Viking Program and the Search for Life
18.8 Searching for Life by Investigating Gases
18.9 Martian Meteorites
18.10 Mars Analog Environments
18.11 Panspermia: The Transfer of Life between Planets?
18.12 Conclusions
Bibliography
19 Ocean Worlds and Icy Moons
19.1 The Astrobiology of Moons
19.2 The Moons of Jupiter: Europa
19.3 The Moons of Jupiter: Ganymede and Callisto
19.4 The Moons of Jupiter: Io
19.5 The Moons of Saturn: Enceladus
19.6 The Moons of Saturn: Titan
19.7 Other Icy Worlds
19.8 Planetary Protection
19.9 Conclusions
Bibliography
20 Exoplanets and the Search for Life
20.1 Exoplanets and Life
20.2 Detecting Exoplanets
20.3 Exoplanet Properties
20.4 Detecting Life
20.5 Surface Biosignatures
20.6 How Likely Are These Signatures?
20.7 Other Ways to Find Life
20.8 Missions to Detect Biosignatures
20.9 Conclusions
Bibliography
21 The Search for Extraterrestrial Intelligence
21.1 The Search for Extraterrestrial Intelligence (SETI)
21.2 Methods in the Search for Extraterrestrial Intelligence
21.3 Communication with Extraterrestrial Intelligence (CETI)
21.4 The Drake Equation
21.5 The Fermi Paradox
21.6 Classifying Civilizations
21.7 Policy Implications
21.8 Conclusions
Bibliography
22 Our Civilization
22.1 Astrobiology and Human Civilization
22.2 The Emergence of Human Society
22.3 Threats to a Civilization
22.4 Climate Change and the Challenge to Civilization
22.5 The Human Future Beyond Earth
22.6 Settling the Solar System
22.7 Avoiding Extinction or Collapse: A Multiplanet Species
22.8 Environmentalism and Space Exploration as a Single Goal?
22.9 Sociology: The Overview Effect
22.10 Will We Become Interstellar?
22.11 Conclusions
Bibliography
Appendix
A.1 The Astrobiology Periodic Table
A.2 Units and Scales
A.3 Temperature Scale Conversion
A.4 Composition of the Sun
A.5 Some of the Major Star Types, Temperatures, and Colors
A.6 Three- and One-Letter Designations of Amino Acids
A.7 Codon Table for the Genetic Code Associated with mRNA (also shown in Chapter 5; Figure 5.12)
A.8 Planetary Data
A.9 Geological Time Scale
Glossary
Index
End User License Agreement