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<p>Acknowledgments xvii</p> <p>About the Companion Website xix</p> <p><b>1 Astrobiology 1</b></p> <p>1.1 Introductory Remarks 1</p> <p>1.2 The Major Questions of Astrobiology and the Content of the Textbook 3</p> <p>1.3 Some Other Features of the Textbook 9</p> <p>1.4 A Brief History of Astrobiology 10</p> <p>1.5 Conclusions 15</p> <p>Bibliography 15</p> <p><b>2 What is Life? 17</b></p> <p>2.1 The Concept of “Life” 17</p> <p>2.2 What is Life? The Historical Perspective 17</p> <p>2.3 Spontaneous Generation 19</p> <p>2.4 More Modern Concepts 23</p> <p>2.5 Schrödinger and Life 27</p> <p>2.6 Life as a Dissipative Process 27</p> <p>2.7 Life: Just a Human Definition? 28</p> <p>2.8 Does It Matter Anyway? 30</p> <p>2.9 Conclusions 30</p> <p>Questions for Review and Reflection 30</p> <p>Bibliography 31</p> <p><b>3 Matter and Life 33</b></p> <p>3.1 Matter and Life 33</p> <p>3.2 Life is Made of “Ordinary” Matter 34</p> <p>3.3 The Atomic Nucleus 34</p> <p>3.4 Electrons, Atoms, and Ions 35</p> <p>3.5 Types of Bonding in Matter 37</p> <p>3.6 Ionic Bonding 38</p> <p>3.7 Covalent Bonding 39</p> <p>3.7.1 Covalent Bonds and Life 40</p> <p>3.8 Metallic Bonding 41</p> <p>3.9 Van der Waals Interactions 42</p> <p>3.10 Hydrogen Bonding 44</p> <p>3.11 An Astrobiological Perspective 46</p> <p>3.12 The Equation of State Describes the Relationship Between Different Types of Matter 47</p> <p>3.13 Other States of Matter 50</p> <p>3.14 The Interaction Between Matter and Light 53</p> <p>3.15 Conclusions 57</p> <p>Questions for Review and Reflection 57</p> <p>Bibliography 57</p> <p><b>4 The Molecular Structure of Life 59</b></p> <p>4.1 Building Life 59</p> <p>4.2 The Essential Elements: CHNOPS 59</p> <p>4.3 Carbon is Versatile 62</p> <p>4.4 The Chains of Life 62</p> <p>4.5 Proteins 63</p> <p>4.6 Chirality 66</p> <p>4.7 Carbohydrates (Sugars) 68</p> <p>4.8 Lipids 71</p> <p>4.9 The Nucleic Acids 72</p> <p>4.10 The Solvent of Life 76</p> <p>4.11 Alternative Chemistries 78</p> <p>4.13 Conclusions 84</p> <p>Questions for Review and Reflection 85</p> <p>Bibliography 85</p> <p><b>5 The Cellular Structure of Life 87</b></p> <p>5.1 From Molecules to Cells 87</p> <p>5.2 Types of Cells 88</p> <p>5.3 Shapes of Cells 90</p> <p>5.4 The Structure of Cells 90</p> <p>5.5 The Structure of Cellular Membranes 91</p> <p>5.6 The Information Storage System of Life 96</p> <p>5.7 Eukaryotic Cells 105</p> <p>5.8 The Reproduction of Cells 107</p> <p>5.9 Why Did Sexual Reproduction Evolve? 108</p> <p>5.10 The Growth of Populations of Cells 110</p> <p>5.11 Moving and Communicating 111</p> <p>5.12 Viruses 116</p> <p>5.13 Prions 118</p> <p>5.14 Conclusions 118</p> <p>Questions for Review and Reflection 119</p> <p>Bibliography 119</p> <p><b>6 Energy for Life 121</b></p> <p>6.1 Energy and Astrobiology 121</p> <p>6.2 Life and Energy 122</p> <p>6.3 The Central Role of Adenosine Triphosphate 123</p> <p>6.4 Chemiosmosis and Energy Acquisition 125</p> <p>6.5 What Types of Electron Donors and Acceptors Can Be Used? 128</p> <p>6.6 Aerobic Respiration 129</p> <p>6.7 Anaerobic Respiration 132</p> <p>6.8 Fermentation 134</p> <p>6.9 Chemoautotrophs: Changing the Electron Donor 134</p> <p>6.10 Energy from Light: Photosynthesis 142</p> <p>6.11 Oxygenic Photosynthesis 142</p> <p>6.12 Anoxygenic Photosynthesis 145</p> <p>6.13 Rhodopsins and Photosynthesis 148</p> <p>6.14 Evolution of Photosynthesis 149</p> <p>6.15 Global Biogeochemical Cycles 150</p> <p>6.16 Microbial Mats – Energy-Driven Zonation in Life 152</p> <p>6.17 The Thermodynamics of Energy Acquisition and Life 154</p> <p>6.18 Energy and Life in Extremes 156</p> <p>6.19 Conclusions 158</p> <p>Questions for Review and Reflection 158</p> <p>Bibliography 158</p> <p><b>7 The Limits of Life 161</b></p> <p>7.1 The Limits of Life 161</p> <p>7.2 The Importance of the Limits of Life for Astrobiology 162</p> <p>7.3 The Most Extreme Conditions are Dominated by Microbes 163</p> <p>7.4 Life at High Temperatures 165</p> <p>7.5 Life at Low Temperatures 167</p> <p>7.6 Salt-Loving Organisms 170</p> <p>7.7 pH Extremes 173</p> <p>7.8 Life Under High Pressure 174</p> <p>7.9 Tolerance to High Radiation 176</p> <p>7.10 Life in Toxic Brews 176</p> <p>7.11 Rocks as a Habitat 177</p> <p>7.12 Polyextremophiles – Dealing with Multiple Extremes 180</p> <p>7.13 Life Underground 181</p> <p>7.14 Dormancy in Extreme Conditions 183</p> <p>7.15 Eukaryotic Extremophiles 184</p> <p>7.16 Are There Other Biospheres with Different Limits? 185</p> <p>7.17 The Limits of Life: Habitability Revisited 186</p> <p>7.18 Conclusions 186</p> <p>Questions for Review and Reflection 186</p> <p>Bibliography 187</p> <p><b>8 The Tree of Life 189</b></p> <p>8.1 A Vast Quantity of Life 189</p> <p>8.2 Evolution and a “Tree of Life” 190</p> <p>8.3 Classifying Organisms 192</p> <p>8.4 The Tree of Life and Some Definitions 194</p> <p>8.5 Problems with Classification: Homology and Analogy 196</p> <p>8.6 Building a Phylogenetic Tree Using Genetic Material 198</p> <p>8.7 Types of Phylogenetic Trees 202</p> <p>8.8 A Modern View of the Tree of Life 202</p> <p>8.9 Using Phylogenetic Trees to Test Hypotheses 204</p> <p>8.10 Complications in Building Trees 206</p> <p>8.11 Origin of Eukaryotes 210</p> <p>8.12 The Last Universal Common Ancestor 211</p> <p>8.13 Multiple Origins of Life? 212</p> <p>8.14 Alien Life 213</p> <p>8.15 Conclusions 214</p> <p>Questions for Review and Reflection 214</p> <p>Bibliography 214</p> <p><b>9 The Universe, the Solar System, and the Elements of Life 217</b></p> <p>9.1 Our Cosmic Situation 217</p> <p>9.2 In the Beginning: The Formation of the Universe 218</p> <p>9.3 Stellar Evolution: Low-Mass Stars 222</p> <p>9.4 Stellar Evolution: High-Mass Stars 224</p> <p>9.5 The Elements of Life 228</p> <p>9.6 The Hertzsprung–Russell Diagram 228</p> <p>9.7 The Sun is a Blackbody 232</p> <p>9.8 The Formation of Planets 233</p> <p>9.9 Types of Objects in Our Solar System 236</p> <p>9.10 Meteorites and Their Classification 239</p> <p>9.11 Laws Governing the Motion of Planetary Bodies 243</p> <p>9.12 Conclusions 245</p> <p>Questions for Review and Reflection 246</p> <p>Bibliography 246</p> <p><b>10 Astrochemistry: Carbon in Space 249</b></p> <p>10.1 Astrochemistry: Carbon Molecules in Space 249</p> <p>10.2 Observing Organics 249</p> <p>10.3 In the Beginning 250</p> <p>10.4 Different Environments for Chemistry 251</p> <p>10.5 How Do Chemical Reactions Occur? 254</p> <p>10.6 Forming Carbon Compounds 256</p> <p>10.7 Formation of Water 257</p> <p>10.8 Interstellar Grains 258</p> <p>10.9 Polycyclic Aromatic Hydrocarbons 258</p> <p>10.10 Even More Carbon Diversity 261</p> <p>10.11 Comets and Organic Molecules 261</p> <p>10.12 The Origin of Chirality 262</p> <p>10.13 Laboratory Experiments 263</p> <p>10.14 Observing Organic Molecules 264</p> <p>10.15 Conclusions 265</p> <p>Questions for Review and Reflection 265</p> <p>Bibliography 266</p> <p><b>11 Early Earth: The First Billion Years 267</b></p> <p>11.1 The First Billion Years of Earth 267</p> <p>11.2 Earth Forms and Differentiates 267</p> <p>11.3 The Formation of the Moon 268</p> <p>11.4 The Early Oceans 270</p> <p>11.5 The Early Crust 273</p> <p>11.6 The Early Atmosphere 273</p> <p>11.7 The Temperature of Early Earth 275</p> <p>11.8 The Late Heavy Bombardment 275</p> <p>11.9 Implications of the Early Environment for Life 278</p> <p>11.10 Conclusions 280</p> <p>Questions for Review and Reflection 280</p> <p>Bibliography 281</p> <p><b>12 The Origin of Life 283</b></p> <p>12.1 The Origin of Life 283</p> <p>12.2 The Synthesis of Organic Compounds on Earth 284</p> <p>12.3 Delivery from the Extraterrestrial Environment 288</p> <p>12.4 The RNA World 291</p> <p>12.5 Early Cells 294</p> <p>12.6 Where Did the Origin of Life Occur? 295</p> <p>12.7 A Cold Origin of Life? 301</p> <p>12.8 The Whole Earth as a Reactor? 301</p> <p>12.9 Conclusions 302</p> <p>Questions for Review and Reflection 302</p> <p>Bibliography 302</p> <p><b>13 Early Life on Earth 305</b></p> <p>13.1 Early Life on Earth 305</p> <p>13.2 Early Life – Metabolisms and Possibilities 305</p> <p>13.3 Isotopic Fractionation 308</p> <p>13.4 Measuring the Isotope Fractionation: The Delta Notation 311</p> <p>13.5 Sulfur Isotope Fractionation 311</p> <p>13.6 Using Isotopes to Look for Ancient Life 312</p> <p>13.7 Morphological Evidence for Life 315</p> <p>13.8 Biomarkers 321</p> <p>13.9 Contamination is a Problem 322</p> <p>13.10 Instruments Used to Look for Life 323</p> <p>13.11 A Brief Summary 326</p> <p>13.12 The Search for Extraterrestrial Life 327</p> <p>13.13 Conclusions 327</p> <p>Questions for Review and Reflection 327</p> <p>Bibliography 327</p> <p><b>14 The Geology of a HabitableWorld 329</b></p> <p>14.1 The Geological History of Earth: A Habitable World 329</p> <p>14.2 Minerals and Glasses 330</p> <p>14.3 Types of Rocks 331</p> <p>14.4 The Rock Cycle 334</p> <p>14.5 The Composition of Earth 336</p> <p>14.6 Plate Tectonics 338</p> <p>14.7 Dating the Age of the Earth (and Other Planetary Bodies) 344</p> <p>14.8 Age-Dating Rocks 345</p> <p>14.9 Geological Timescales 352</p> <p>14.10 The Major Classifications of Geological Time 352</p> <p>14.11 Some Geological Times and Biological Changes 353</p> <p>14.12 Conclusions 360</p> <p>Questions for Review and Reflection 360</p> <p>Bibliography 360</p> <p><b>15 The Co-evolution of Life and a Planet: The Rise of Oxygen 363</b></p> <p>15.1 Dramatic Changes on Earth 363</p> <p>15.2 Measuring Oxygen Through Time 364</p> <p>15.3 It Was Not a Simple Rise 368</p> <p>15.4 Summarizing the Evidence for the GOE 370</p> <p>15.5 The Source of Oxygen 371</p> <p>15.6 Sinks for Oxygen 371</p> <p>15.7 Why Did Atmospheric Oxygen Concentrations Rise? 372</p> <p>15.8 Snowball Earth Episodes 373</p> <p>15.9 Other Biological Consequences of the Rise of Oxygen 376</p> <p>15.10 Oxygen and the Rise of Animals 377</p> <p>15.11 Oxygen and the Rise of Intelligence 379</p> <p>15.12 Periods of High Oxygen 379</p> <p>15.13 Conclusions 380</p> <p>Questions for Review and Reflection 380</p> <p>Bibliography 381</p> <p><b>16 Mass Extinctions 383</b></p> <p>16.1 Extinctions 383</p> <p>16.2 What is Extinction? 383</p> <p>16.3 Five Major Mass Extinctions 385</p> <p>16.4 Other Extinctions in Earth History 386</p> <p>16.5 Causes of Mass Extinction 386</p> <p>16.6 The End-Cretaceous Extinction 388</p> <p>16.7 The Other Four Big Extinctions of the Phanerozoic 392</p> <p>16.8 Do Microorganisms Go Extinct? 396</p> <p>16.9 Recovery from Extinction 396</p> <p>16.10 Can We Avoid Extinction? 398</p> <p>16.11 The Sixth Mass Extinction? 400</p> <p>16.12 Conclusions 401</p> <p>Questions for Review and Reflection 401</p> <p>Bibliography 401</p> <p><b>17 The Habitability of Planetary Bodies 403</b></p> <p>17.1 What is “Habitability”? 403</p> <p>17.2 The Habitable Zone 405</p> <p>17.3 Maintaining Temperature Conditions on a Planet Suitable for Water and Life 408</p> <p>17.4 Plate Tectonics and Habitability 414</p> <p>17.5 Does the Moon Play a Role in Habitability? 416</p> <p>17.6 Other Planetary Factors that Influence Habitability 417</p> <p>17.7 Surface Liquid Water, Habitability, and Intelligence 418</p> <p>17.8 Habitable Environments Need Not Always Contain Life 418</p> <p>17.9 Worlds More Habitable than Earth? 420</p> <p>17.10 The Anthropic Principle and Habitability 420</p> <p>17.11 The Fate of Earth 420</p> <p>17.12 The Galactic Habitable Zone 421</p> <p>17.13 The Right Galaxy? 422</p> <p>17.14 Conclusions 422</p> <p>Questions for Review and Reflection 423</p> <p>Bibliography 423</p> <p><b>18 The Astrobiology of Mars 425</b></p> <p>18.1 Mars and Astrobiology 425</p> <p>18.2 Martian Geological History: A Very Brief Summary 426</p> <p>18.3 The Environmental Deterioration of Mars 427</p> <p>18.4 Missions to Mars 429</p> <p>18.5 Mars and Life 435</p> <p>18.6 Trajectories of Martian Habitability 451</p> <p>18.7 The Viking Program and the Search for Life 455</p> <p>18.8 Searching for Life by Investigating Gases 458</p> <p>18.9 Martian Meteorites 458</p> <p>18.10 Mars Analog Environments 460</p> <p>18.11 Panspermia: The Transfer of Life between Planets? 463</p> <p>18.12 Conclusions 467</p> <p>Questions for Review and Reflection 467</p> <p>Bibliography 468</p> <p><b>19 Ocean Worlds and Icy Moons 471</b></p> <p>19.1 The Astrobiology of Moons 471</p> <p>19.2 The Moons of Jupiter: Europa 472</p> <p>19.3 The Moons of Jupiter: Ganymede and Callisto 477</p> <p>19.4 The Moons of Jupiter: Io 479</p> <p>19.5 The Moons of Saturn: Enceladus 479</p> <p>19.6 The Moons of Saturn: Titan 484</p> <p>19.7 Other Icy Worlds 490</p> <p>19.8 Planetary Protection 494</p> <p>19.9 Conclusions 496</p> <p>Questions for Review and Reflection 496</p> <p>Bibliography 496</p> <p><b>20 Exoplanets and the Search for Life 499</b></p> <p>20.1 Exoplanets and Life 499</p> <p>20.2 Detecting Exoplanets 500</p> <p>20.3 Exoplanet Properties 508</p> <p>20.4 Detecting Life 517</p> <p>20.5 Surface Biosignatures 522</p> <p>20.6 How Likely are These Signatures? 525</p> <p>20.7 Other Ways to Find Life 525</p> <p>20.8 Missions to Detect Biosignatures 526</p> <p>20.9 Conclusions 527</p> <p>Questions for Review and Reflection 527</p> <p>Bibliography 528</p> <p><b>21 The Search for Extraterrestrial Intelligence 529</b></p> <p>21.1 The Search for Extraterrestrial Intelligence (SETI) 529</p> <p>21.2 Methods in the Search for Extraterrestrial Intelligence 530</p> <p>21.3 Communication with Extraterrestrial Intelligence (CETI) 533</p> <p>21.4 The Drake Equation 537</p> <p>21.5 The Fermi Paradox 538</p> <p>21.6 Classifying Civilizations 542</p> <p>21.7 Policy Implications 543</p> <p>21.8 Conclusions 544</p> <p>Questions for Review and Reflection 544</p> <p>Bibliography 544</p> <p><b>22 Our Civilization 547</b></p> <p>22.1 Astrobiology and Human Civilization 547</p> <p>22.2 The Emergence of Human Society 547</p> <p>22.3 Threats to a Civilization 551</p> <p>22.4 Climate Change and the Challenge to Civilization 553</p> <p>22.5 The Human Future Beyond Earth 555</p> <p>22.6 Settling the Solar System 556</p> <p>22.7 Avoiding Extinction or Collapse: A Multiplanet Species 565</p> <p>22.8 Environmentalism and Space Exploration as a Single Goal? 566</p> <p>22.9 Sociology: The Overview Effect 567</p> <p>22.10 Will We Become Interstellar? 568</p> <p>22.11 Conclusions 569</p> <p>Questions for Review and Reflection 569</p> <p>Bibliography 569</p> <p><b>Appendix 571</b></p> <p>A.1 The Astrobiology Periodic Table 571</p> <p>A.2 Units and Scales 571</p> <p>A.2.1 Standard International Base Units 571</p> <p>A.2.2 Basic Physical Constants 572</p> <p>A.3 Temperature Scale Conversion 572</p> <p>A.4 Composition of the Sun 573</p> <p>A.5 Some of the Major Star Types, Temperatures, and Colors 573</p> <p>A.6 Three- and One-Letter Designations of Amino Acids 573</p> <p>A.7 Codon Table for the Genetic Code Associated with mRNA (also shown in Chapter 5; Figure 5.12) 574</p> <p>A.8 Planetary Data 575</p> <p>A.9 Geological Time Scale 576</p> <p>Glossary 577</p> <p>Index 601</p>

<p><b>CHARLES S. COCKELL</b> is Professor of Astrobiology at the University of Edinburgh, United Kingdom.

<p><b>A guide to understanding the formation of life in the Universe</b> <p>The revised and updated second edition of??<i>Astrobiology</i>??offers an introductory text that explores the structure of living things, the formation of the elements required for life in the Universe, the biological and geological history of the Earth, and the habitability of other planets. Written by a noted expert on the topic, the book examines many of the major conceptual foundations in astrobiology, which cover a diversity of traditional fields including chemistry, biology, geosciences, physics, and astronomy. <p>The book explores many profound questions such as: How did life originate on Earth? How has life persisted on Earth for over three billion years? Is there life elsewhere in the Universe? What is the future of life on Earth???<i>Astrobiology</i>??is centered on investigating the past and future of life on Earth by looking beyond Earth to get the answers. Astrobiology links the diverse scientific fields needed to understand life on our own planet and, potentially, life beyond. This new second edition: <ul> <li>Expands on information about the nature of astrobiology and why it is useful</li> <li>Contains a new chapter "What is Life?" that explores the history of attempts to understand life</li> <li>Contains 20% more material on the astrobiology of Mars, icy moons, the structure of life, and the habitability of planets</li> <li>New 'Discussion Boxes' to stimulate debate and thought about key questions in astrobiology</li> <li>New review and reflection questions for each chapter to aid learning</li> <li>New boxes describing the careers of astrobiologists and how they got into the subject</li> <li>Offers revised and updated information throughout to reflect the latest advances in the field</li> </ul> <p>Written for students of life sciences, physics, astronomy and related disciplines, the updated edition of??<i>Astrobiology</i>??is an essential introductory text that includes recent advances to this dynamic field.

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