Оглавление
Charles S. Cockell. Astrobiology
Table of Contents
List of Tables
List of Illustrations
Guide
Pages
Astrobiology. Understanding Life in the Universe
Acknowledgments
About the Companion Website
1 Astrobiology. Learning Outcomes
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. Books
Papers
2 What Is Life? Learning Outcomes
2.1 The Concept of “Life”
2.2 What Is Life? The Historical Perspective
2.3 Spontaneous Generation
Focus: Astrobiologists: Mary Beth Wilhelm
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
Questions for Review and Reflection
Bibliography. Books
Papers
3 Matter and Life. Learning Outcomes
3.1 Matter and Life
3.2 Life Is Made of “Ordinary” Matter
3.3 The Atomic Nucleus
3.3.1 Isotopes
3.4 Electrons, Atoms, and Ions
3.5 Types of Bonding in Matter
3.6 Ionic Bonding
3.6.1 Ionic Bonds and Life
3.7 Covalent Bonding
3.7.1 Covalent Bonds and Life
3.8 Metallic Bonding
Discussion Point: Why Doesn't Terrestrial Biochemistry Use Metal Structures?
3.9 Van der Waals Interactions
3.9.1 Dipole–Dipole (Keesom) Forces
3.9.2 Dipole-Induced Dipole (Debye; Pronounced Deh-beye) Forces
3.9.3 Dispersion Forces
3.9.4 Van der Waals Interactions and Life
Focus: Astrobiologists: Andreas Elsaesser
3.10 Hydrogen Bonding
3.10.1 Hydrogen Bonds and Life
3.11 An Astrobiological Perspective
Discussion Point: Is the Structure of Life Universal?
3.12 The Equation of State Describes the Relationship Between Different Types of Matter
3.12.1 Phase Diagrams
3.12.2 Phase Diagrams and Mars
3.12.3 Phase Diagrams and Life
3.13 Other States of Matter
3.13.1 Plasma
3.13.2 Degenerate Matter
Discussion Point: Can Life be Made from Different States of Matter to Terrestrial Life?
3.14 The Interaction Between Matter and Light
3.14.1 The Special Case of the Hydrogen Atom
3.14.2 Uses for Astrobiology
3.15 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
4 The Molecular Structure of Life. Learning Outcomes
4.1 Building Life
4.2 The Essential Elements: CHNOPS
Discussion Point: Are the Minimal CHNOPS Elements a Universal Requirement for Life?
4.3 Carbon Is Versatile
4.4 The Chains of Life
Discussion Point: Searching for Life Without Knowing Anything About it
4.5 Proteins
Discussion Point: Why Does Life Use the 20 Particular Amino Acids it Has?
4.6 Chirality
Discussion Point: Life with a Different Chirality
4.7 Carbohydrates (Sugars)
Focus: Astrobiologists: Scott Perl
4.8 Lipids
4.9 The Nucleic Acids
4.9.1 Ribonucleic Acid
Discussion Point: How Different Could the Genetic Code Be?
4.10 The Solvent of Life
4.10.1 Water as a Solvent
4.11 Alternative Chemistries
4.11.1 Alternative Core Elements
4.11.2 Alternative Solvents
4.12 The Structure of Life and Habitability
4.13 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
5 The Cellular Structure of Life. Learning Outcomes
5.1 From Molecules to Cells
5.2 Types of Cells
Discussion Point: Must Life Be Cellular?
5.3 Shapes of Cells
5.4 The Structure of Cells
5.5 The Structure of Cellular Membranes
5.5.1 Gram-Negative and -Positive Prokaryotic Membranes
Discussion Point: Are Prokaryotes “Simple”?
5.5.2 Archaeal Membranes
5.6 The Information Storage System of Life
5.6.1 Transcription – DNA to RNA
5.6.2 Translation – RNA to Protein
Discussion Point: Why Is There Degeneracy in the Genetic Code?
5.6.3 A Remarkable Code
5.6.4 The Evolution of the Codons
Discussion Point: The Universality of the Genetic Structure and Machinery
Focus: Astrobiologists: Nicol Caplin
5.6.5 DNA Replication
5.6.6 Plasmids
Discussion Point: What Is the Minimum Size of a Cell?
5.6.7 eDNA
5.7 Eukaryotic Cells
5.7.1 Endosymbiosis
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
5.11.1 Movement in Prokaryotes
Discussion Point: Rotating Structures in Nature – Why Don't Animals Have Wheels?
5.11.2 Communication in Prokaryotes
5.11.3 “Multicellularity” in Prokaryotes and Single-Celled Eukaryotes
Discussion Point: When Did Multicellularity Evolve?
5.12 Viruses
Discussion Point: Astrobiology and Viruses
5.13 Prions
5.14 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
6 Energy for Life. Learning Outcomes
6.1 Energy and Astrobiology
6.2 Life and Energy
6.3 The Central Role of Adenosine Triphosphate
6.4 Chemiosmosis and Energy Acquisition
Discussion Point: Energy from Something Other Than Electrons?
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
Focus: Astrobiologists: Haley Sapers
6.9.1 Chemoautotrophy and Fixing CO2
6.9.2 Methanogens and Insights into the Evolution of Metabolism
6.9.3 How Universal Is Metabolism? The TCA Cycle Revisited
Discussion Point: Are Metabolic Pathways Universal?
6.9.4 Methanotrophs
Discussion Point: Geochemical Disequilibria, Planets, and Life
6.9.5 Sulfur Cycling
6.9.6 Iron Oxidizers
6.9.7 Nitrogen Cycling and the Chemoautotrophs
6.10 Energy from Light: Photosynthesis
6.11 Oxygenic Photosynthesis
Discussion Point: Is Oxygenic Photosynthesis Inevitable?
6.12 Anoxygenic Photosynthesis
6.13 Rhodopsins and Photosynthesis
6.14 Evolution of Photosynthesis
6.15 Global Biogeochemical Cycles
Discussion Point: Life Independent of Photosynthesis
6.16 Microbial Mats – Energy-Driven Zonation in Life
6.17 The Thermodynamics of Energy Acquisition and Life
6.17.1 Gibbs Free Energy: The Energy in Reactants and Products
6.17.2 Gibbs Free Energy: The Concentration of Compounds
6.17.3 Gibbs Free Energy: Using Redox Reactions
6.17.4 Gibbs Free Energy: An Example
6.18 Energy and Life in Extremes
6.19 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
7 The Limits of Life. Learning Outcomes
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
Focus: Astrobiologists: Alexandra Pontefract
7.4.1 Uses for Thermostable Molecules
7.5 Life at Low Temperatures
Facilities Focus: Underground Laboratories
7.6 Salt-Loving Organisms
7.6.1 Salt-In Strategy
7.6.2 Salt-Out Strategy
7.6.3 Low Water Activity
Discussion Point: Salts in the Universe
7.7 pH Extremes
7.8 Life Under High Pressure
Focus: Astrobiologists: David Smith
7.9 Tolerance to High Radiation
7.10 Life in Toxic Brews
7.11 Rocks as a Habitat
Facilities Focus: Labs in Other Extreme Environments
7.12 Polyextremophiles – Dealing with Multiple Extremes
Discussion Point: The Limits of Life – Are They Universal?
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
Questions for Review and Reflection
Bibliography. Books
Papers
8 The Tree of Life. Learning Outcomes
8.1 A Vast Quantity of Life
Discussion Point: How Much Life Is There on Earth?
8.2 Evolution and a “Tree of Life”
8.3 Classifying Organisms
8.4 The Tree of Life and Some Definitions
Discussion Point: Must All Life Be Assembled into Some Type of Tree?
8.5 Problems with Classification: Homology and Analogy
Discussion Point: Vestigiality, Chance, or Function?
8.6 Building a Phylogenetic Tree Using Genetic Material
Focus: Astrobiologists: Sanjoy Som
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
8.10.1 Endosymbiosis
8.10.2 Horizontal Gene Transfer
Discussion Point: Is the Tree of Life a Mirage?
8.11 Origin of Eukaryotes
8.12 The Last Universal Common Ancestor
Discussion Point: Can We Ever Know the LUCA?
8.13 Multiple Origins of Life?
Discussion Point: Shadow Biospheres?
8.14 Alien Life
8.15 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
9 The Universe, the Solar System, and the Elements of Life. Learning Outcomes
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
Facilities Focus: Space Telescopes and Observatories
Focus: Astrobiologists: Jason Wright
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
Discussion Point: Old Meteorites and Their Preservation
9.11 Laws Governing the Motion of Planetary Bodies
9.12 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
10 Astrochemistry: Carbon in Space. Learning Outcomes
10.1 Astrochemistry: Carbon Molecules in Space
10.2 Observing Organics
10.3 In the Beginning
10.4 Different Environments for Chemistry
10.4.1 Diffuse Interstellar Clouds
10.4.2 Molecular Clouds
10.4.3 Protoplanetary Discs
10.4.4 Carbon-Rich Stars
10.4.5 Shock Waves from Supernova Explosions
10.5 How Do Chemical Reactions Occur?
10.6 Forming Carbon Compounds
10.7 Formation of Water
Discussion Point: Water as a Solvent for Life
10.8 Interstellar Grains
10.9 Polycyclic Aromatic Hydrocarbons
10.10 Even More Carbon Diversity
10.10.1 Prebiotic Compounds
10.11 Comets and Organic Molecules
10.12 The Origin of Chirality
10.13 Laboratory Experiments
Discussion Point: Replicating Interstellar Conditions in the Laboratory
10.14 Observing Organic Molecules
10.15 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
11 Early Earth: The First Billion Years. Learning Outcomes
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
General Focus: Astrobiologists: Ania Losiak
11.5 The Early Crust
11.6 The Early Atmosphere
11.7 The Temperature of Early Earth
11.8 The Late Heavy Bombardment
Discussion Point: Age Dating Using Craters
11.9 Implications of the Early Environment for Life
Discussion Point: Radiation – Good for Life?
11.10 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
12 The Origin of Life. Learning Outcomes
12.1 The Origin of Life
12.2 The Synthesis of Organic Compounds on Earth
Discussion Point: Is the Origin of Life Inevitable?
12.2.1 Possible Reaction Pathways
12.3 Delivery from the Extraterrestrial Environment
Focus: Astrobiologists: Sarah Stewart Johnson
12.4 The RNA World
Discussion Point: What Came First?
12.5 Early Cells
12.6 Where Did the Origin of Life Occur?
12.6.1 Deep Sea Hydrothermal Vents
12.6.2 Land-Based Volcanic Environments
12.6.3 Impact Craters
12.6.4 On the Beach
12.6.5 Atmospheric Bubbles
12.6.6 The Deep Subsurface
12.6.7 Mineral Surfaces
12.7 A Cold Origin of Life?
12.8 The Whole Earth as a Reactor?
Discussion Point: No Specific Location for the Emergence of the First Cell?
12.9 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
13 Early Life on Earth. Learning Outcomes
13.1 Early Life on Earth
13.2 Early Life – Metabolisms and Possibilities
13.3 Isotopic Fractionation
General Focus: Astrobiologists: Sean McMahon
13.3.1 Carbon Isotopes
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
13.7.1 How Are Microorganisms Fossilized?
13.7.2 Evidence for Ancient Fossil Microbial Life
General Focus: Astrobiologists: Nicola McLoughlin
13.7.3 Stromatolites
Discussion Point: Stromatolite Structures Without Biology?
Discussion Point: MISS On Mars?
13.8 Biomarkers
13.9 Contamination Is a Problem
13.10 Instruments Used to Look for Life
Facilities Focus: Nano Secondary Ion Mass Spectrometry (Nano-SIMS)
13.11 A Brief Summary
13.12 The Search for Extraterrestrial Life
13.13 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
14 The Geology of a Habitable World. Learning Outcomes
14.1 The Geological History of Earth: A Habitable World
14.2 Minerals and Glasses
14.3 Types of Rocks
14.3.1 Igneous Rocks
General Facilities Focus: Studying Rocks and Planetary Materials
14.3.2 Sedimentary Rocks
14.3.3 Metamorphic Rocks
14.4 The Rock Cycle
Discussion Point: Anthropic Rocks
14.5 The Composition of Earth. 14.5.1 The Core and Earth's Magnetic Field
Discussion Point: Is a Magnetic Field Required for Life?
14.5.2 The Mantle
14.5.3 Earth's Crust and Upper Mantle
14.6 Plate Tectonics
Discussion Point: Plate Tectonics and Planetary Habitability
Discussion Point: Plate Tectonics and the Origin of Life
14.7 Dating the Age of the Earth (and Other Planetary Bodies)
General Focus: Astrobiologists: Feng Tian
14.8 Age-Dating Rocks
14.8.1 Absolute Age Dating of Rocks
14.8.1.1 The Isochron Method of Age Dating
14.8.1.2 Extinct Radioisotopes
14.8.2 Relative Dating of Rocks
14.8.2.1 The Principle of Superposition
14.8.2.2 The Principle of Original Horizontality
14.8.2.3 The Principle of Crosscutting Relationships
14.8.2.4 The Principle of Faunal Succession
14.8.3 Unconformities
14.8.3.1 Non-conformity
14.8.3.2 Angular Unconformity
14.8.3.3 Disconformity
14.9 Geological Timescales
14.10 The Major Classifications of Geological Time
14.11 Some Geological Times and Biological Changes
14.11.1 The Precambrian
14.11.2 The Phanerozoic: The Rise of Animals and Complexity
14.11.2.1 The Paleozoic Era
14.11.2.2 The Mesozoic Era
14.11.2.3 The Cenozoic Era
Discussion Point: The Anthropocene
14.12 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
15 The Co-evolution of Life and a Planet: The Rise of Oxygen. Learning Outcomes
15.1 Dramatic Changes on Earth
15.2 Measuring Oxygen Through Time
15.2.1 Minerals that Form at Low Oxygen Concentrations
15.2.2 Changes in the Oxidation State of Elements
15.2.3 Banded Iron Formations and Their Isotopes
15.2.4 Sulfur Isotope Fractionation
15.3 It Was Not a Simple Rise
15.4 Summarizing the Evidence for the GOE
General Focus: Astrobiologists: Jacob Haqq-Misra
15.5 The Source of Oxygen
15.6 Sinks for Oxygen
15.7 Why Did Atmospheric Oxygen Concentrations Rise?
15.8 Snowball Earth Episodes
Discussion Point: Life on a Present-Day Snowball Earth
15.9 Other Biological Consequences of the Rise of Oxygen
15.10 Oxygen and the Rise of Animals
Discussion Point: The Rise of Oxygen on Other Planets
15.11 Oxygen and the Rise of Intelligence
15.12 Periods of High Oxygen
15.13 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
16 Mass Extinctions. Learning Outcomes
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
16.5.1 Volcanic Causes
16.5.2 Sea-Level Changes
16.5.3 Asteroid and Comet Impacts
16.5.4 Biological Changes
16.5.5 Supernova Explosions and Gamma Ray Bursts
16.5.6 Multiple Effects
16.6 The End-Cretaceous Extinction
16.6.1 Evidence for Asteroid Impact
Discussion Point: What if... The K–Pg Extinction Didn't Happen?
16.6.2 Other Mechanisms for Extinction at the K–Pg Boundary
16.7 The Other Four Big Extinctions of the Phanerozoic. 16.7.1 End-Ordovician Mass Extinction
16.7.2 Late Devonian Mass Extinction
16.7.3 The Largest of all Mass Extinctions: The End-Permian Extinction
16.7.4 End-Triassic Mass Extinction
16.8 Do Microorganisms Go Extinct?
16.9 Recovery from Extinction
16.10 Can We Avoid Extinction?
16.11 The Sixth Mass Extinction?
Discussion Point: The Sixth Extinction
16.12 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
17 The Habitability of Planetary Bodies. Learning Outcomes
17.1 What Is “Habitability”?
Discussion Point: Is Habitability a Binary Property?
17.2 The Habitable Zone
17.2.1 Effects of Star Types on Habitability
17.2.2 Continuously Habitable Zone
17.2.3 Pre- and Post-Main Sequence Stars
17.3 Maintaining Temperature Conditions on a Planet Suitable for Water and Life
17.3.1 Effective Temperature and the Greenhouse Effect
17.3.1.1 Calculating the Effective Temperature of a Planet
17.3.1.2 The Greenhouse Effect
Discussion Point: Atmospheric Habitability and Airborne Biospheres
17.3.2 The Carbonate–Silicate Cycle
General Focus: Astrobiologists: Shawn Domagal-Goldman
17.3.3 Habitable Conditions Underground and on Lone Planets?
17.4 Plate Tectonics and Habitability
Discussion Point: The Factors Required for Habitability
17.5 Does the Moon Play a Role in Habitability?
General Focus: Astrobiologists: Robin Wordsworth
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
Questions for Review and Reflection
Bibliography. Books
Papers
18 The Astrobiology of Mars. Learning Outcomes
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
18.5.1 Water and Mars. 18.5.1.1 The Evidence for Water on Mars
Discussion Point: Mars – A Better Place to Look for Early Life than Earth?
18.5.1.2 Liquid Water on Mars Today
18.5.2 Basic Elements for Life on Mars
18.5.2.1 Carbon
18.5.2.2 Hydrogen
18.5.2.3 Nitrogen
18.5.2.4 Oxygen
18.5.2.5 Phosphorus
18.5.2.6 Sulfur
18.5.3 Trace Elements for Life on Mars
18.5.4 Energy and Redox Couples for Life on Mars
General Focus: Astrobiologists: Ralf Moeller
18.5.5 Physical Limits to Life: Radiation
18.5.6 Physical Limits to Life: pH
18.5.7 Physical Limits to Life: Salts
18.5.8 Habitat Space for Microbes on Mars
18.6 Trajectories of Martian Habitability
18.6.1 Trajectories for an Uninhabited Mars
General Facilities Focus: Mars Simulation Chambers
18.6.2 Trajectories for an Inhabited Mars
18.7 The Viking Program and the Search for Life
18.7.1 GC–MS Analysis
18.7.2 Gas-Exchange Experiment
18.7.3 Labeled Release Experiment
18.7.4 Pyrolytic Release Experiment
18.7.5 Viking: A Lesson in Science
18.8 Searching for Life by Investigating Gases
18.9 Martian Meteorites
18.10 Mars Analog Environments
Discussion Point: Astrobiology, Extraterrestrial Life, and Science
18.11 Panspermia: The Transfer of Life between Planets?
18.11.1 Ejection from a Planet
18.11.2 Interplanetary Transfer Phase
18.11.3 Arriving at the Destination Planet
18.12 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
19 Ocean Worlds and Icy Moons. Learning Outcomes
19.1 The Astrobiology of Moons
19.2 The Moons of Jupiter: Europa
Discussion Point: Plate Tectonics on Europa
19.2.1 A Subsurface Ocean
19.2.1.1 Habitable Conditions in Europa's Ocean?
19.3 The Moons of Jupiter: Ganymede and Callisto
19.4 The Moons of Jupiter: Io
19.5 The Moons of Saturn: Enceladus
general Focus: Astrobiologists: Nozair Khawaja
19.5.1 The Plumes of Enceladus
Discussion Point: The Exploration of Ocean Worlds
19.6 The Moons of Saturn: Titan
19.7 Other Icy Worlds
19.7.1 Ceres
19.7.2 Neptune's Moon Triton
19.7.3 Pluto
19.8 Planetary Protection
Discussion Point: Is Planetary Protection Necessary?
19.9 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
20 Exoplanets and the Search for Life. Learning Outcomes
20.1 Exoplanets and Life
20.2 Detecting Exoplanets. 20.2.1 The Challenge of Detection
20.2.2 Transit Method
20.2.3 Doppler Shift/Radial Velocity Method
20.2.4 Astrometry
General Focus: Astrobiologists: Sarah Rugheimer
20.2.5 Variations in Other Attributes of Stars
20.2.6 Orbital Brightness Changes
20.2.7 Gravitational Lensing
20.2.8 Direct Detection
20.2.9 Using Direct Detection to Study Protoplanetary Discs
20.3 Exoplanet Properties. 20.3.1 General Properties
20.3.2 Hot Jupiters and Neptunes
20.3.3 Super-Earths and Ocean Worlds
20.3.3.1 Plate Tectonics and Habitability on Super-Earths and Ocean Worlds
20.3.4 Rocky Planets in the Habitable Zone
Discussion Point: Rare Earth?
20.3.5 Planets in Binary and Multiple Star Systems
20.3.6 Strange Worlds
20.3.7 Habitable Exomoons?
General Focus: Astrobiologists: Eddie Schwieterman
20.4 Detecting Life. 20.4.1 Biosignature Gases
20.4.2 Oxygen as a Biosignature Gas and Atmospheric Disequilibria with Oxygen
Discussion Point: How Universal Are Biosignature Gases?
20.4.3 False Positives and False Negatives
20.4.4 Anti-Biosignature Gases
20.4.5 Other Biosignature Gases
20.4.6 Technosignature Gases
20.5 Surface Biosignatures
Discussion Point: What Happens after a Biosignature Detection?
20.6 How Likely Are These Signatures?
20.7 Other Ways to Find Life
20.8 Missions to Detect Biosignatures
20.9 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
21 The Search for Extraterrestrial Intelligence. Learning Outcomes
21.1 The Search for Extraterrestrial Intelligence (SETI)
21.2 Methods in the Search for Extraterrestrial Intelligence
21.2.1 Searching in the Radio Region of the Electromagnetic Spectrum
21.2.2 Searching in the Optical Region of the Electromagnetic Spectrum
21.2.3 The Significance of Exoplanet Research
21.2.4 The Search for Extraterrestrial Artifacts (SETA)
21.3 Communication with Extraterrestrial Intelligence (CETI)
21.4 The Drake Equation
Discussion Point: The Drake Equation
21.5 The Fermi Paradox
21.5.1 Civilizations Are Too Far Apart in Space
21.5.2 No Other, or Very Few, Civilizations Have Arisen
Discussion Point: Is the Fermi Paradox a Scientific Hypothesis?
21.5.3 Intelligent Life Destroys Itself
21.5.4 Civilizations Are Periodically Destroyed by Natural Events
21.5.5 It Is the Nature of Intelligent Life to Destroy Other Civilizations
21.5.6 They Exist, But We See No Evidence of Them
21.5.7 They Are in the Local Area, But Observing Us Rather than Attempting to Make Contact
21.5.8 They Are Too Busy Online
21.5.9 They Are Here
21.5.10 The Evidence Is Being Suppressed
21.6 Classifying Civilizations
21.7 Policy Implications
21.8 Conclusions
Questions for Review and Reflection
Bibliography. Books
Papers
22 Our Civilization. Learning Outcomes
22.1 Astrobiology and Human Civilization
22.2 The Emergence of Human Society
22.3 Threats to a Civilization
22.3.1 Supervolcanoes
22.3.2 Asteroid and Comet Impacts
22.3.3 Disease
22.4 Climate Change and the Challenge to Civilization
22.5 The Human Future Beyond Earth
22.5.1 The Rocket Equation
22.6 Settling the Solar System. 22.6.1 Where First?
Discussion Point: What Does It Take to Live Self-Sufficiently on the Moon and Mars?
22.6.2 Life Support Systems
22.6.2.1 Compartment 1: The Liquefying Compartment
22.6.2.2 Compartment 2: The Photoheterotrophic Compartment
22.6.2.3 Compartment 3: The Nitrifying Compartment
22.6.2.4 Compartment 4: The Photoautotrophic Compartment
General Focus: Astrobiologists: Octavio A. Chon Torres
22.6.3 Human Exploration of Mars
Discussion Point: Terraforming
22.6.4 The Asteroids
22.6.5 The Outer Solar System
22.6.6 Large Human Settlements in Space
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
Questions for Review and Reflection
Bibliography. Books
Papers
Appendix. A.1 The Astrobiology Periodic Table
A.2 Units and Scales. A.2.1 Standard International Base Units
A.2.2 Basic Physical Constants
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
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