Planetary Systems and the Origins of Life (Cambridge Astrobiology)

Half-title......Page 3
Series-title......Page 4
Title......Page 5
Copyright......Page 6
Contents......Page 7
Contributors......Page 13
Preface......Page 17
Part I Planetary systems and the origins of life......Page 21
1.1 Introduction......Page 23
1.2 RV detections......Page 24
1.3 Transit detections......Page 27
1.4.1 Mass distribution......Page 30
1.4.3 Orbital eccentricities......Page 31
1.4.6 Planetary radii......Page 32
1.5.1 Astrometry......Page 34
1.5.4 Gravitational lensing......Page 35
1.6 Future prospects for space missions......Page 36
References......Page 37
2.2 The primary eclipse......Page 41
2.3 The secondary eclipse......Page 43
2.4 Characteristics of known transiting planets......Page 45
2.5 Spectroscopy......Page 47
2.6 Model atmospheres......Page 50
2.7 Observations......Page 52
2.8 Future missions......Page 55
2.9 Summary......Page 57
References......Page 58
3.1 Introduction......Page 61
3.2 The formation of planetesimals......Page 62
3.3 The growth of protoplanets......Page 63
3.4 The growth of planets......Page 67
3.6 Terrestrial planets and life......Page 72
3.7 Summary......Page 76
References......Page 77
4.1 Introduction......Page 82
4.2 Protoplanetary disks and the formation of planet systems......Page 83
4.3 Protoplanetary disks and the formation of biomolecules......Page 88
4.4 Measurements and experiments on amino acid synthesis......Page 91
4.5 A role for thermodynamics......Page 93
4.6 The RNA world and the origin of the genetic code......Page 96
4.7 How was the genetic code optimized?......Page 100
4.8 Protein evolution......Page 102
References......Page 104
5.2 Defining emergence......Page 109
5.3 Emergence of life: a very brief history......Page 110
5.4 The first emergent phenomena: self-assembly processes on the early Earth......Page 111
5.5 Sources of amphiphilic molecules......Page 112
5.6 The emergence of primitive cells......Page 115
5.7 Self-assembly processes in prebiotic organic mixtures......Page 120
5.8 Emergence of membrane functions......Page 121
5.9 Emergence of growth processes in primitive cells......Page 123
5.10 Environmental constraints on the first forms of life......Page 125
References......Page 126
Part II Life on Earth......Page 131
6.1 Introduction......Page 133
6.2 What is an extremophile?......Page 134
6.4.1 Temperature......Page 135
6.4.2 pH limits for life......Page 140
6.4.4 Desiccation (anhydrobiosis)......Page 141
6.4.6 Radiation......Page 142
6.5 How do they do it?......Page 143
6.6 Examples of extreme ecosystems......Page 145
6.7 Space: new categories of extreme environments......Page 146
6.8.1 Venus......Page 147
6.8.2 Mars......Page 148
6.8.3 Europa......Page 149
6.9 Conclusions......Page 150
References......Page 151
7.1 Introduction......Page 155
7.2.1 Terrestrial biotopes......Page 156
7.2.2 Marine biotopes......Page 157
7.3 Sampling and cultivation......Page 158
7.4 Phylogenetic implications......Page 159
7.5.1 Energy sources......Page 161
7.6 Examples of recent HT organisms......Page 163
References......Page 167
8.2.1 The homology criterion......Page 169
8.2.2 Cladistics and maximum parsimony......Page 170
8.3.2 Systematic biases and non-phylogenetic signals......Page 172
8.3.3 Gene duplication and horizontal gene transfer......Page 174
8.4.1 Stochastic error and the need for more data......Page 175
8.4.3 State of the art in evolutionary models......Page 176
8.4.5 Corroboration from non-sequence-based phylogenomic methods......Page 177
8.4.6 Case study: resolution of the metazoan evolution......Page 178
8.5.1 The rise and fall of Archezoa......Page 180
8.5.3 Current view of eukaryotic evolution......Page 182
8.5.4 Philosophical grounds for the rejection of secondary simplification......Page 183
8.6.1 Solid facts and open questions......Page 184
8.6.2 The current paradigm: a bacterial rooting of the tree of life and a sister-group relationship between Archaea and Eukaryotes......Page 185
8.7.1 A genome fusion at the origin of eukaryotes......Page 187
8.7.2 A hyperthermophilic origin of life......Page 189
Acknowledgements......Page 191
References......Page 192
9.1 Introduction......Page 198
9.2 How to analyse multigene data?......Page 199
9.3 What does the plurality consensus represent? Example of smallmarine cyanobacteria......Page 202
9.4 Where is the root of the `tree of life'?......Page 203
9.5 Use of higher order characters: example of ATPases......Page 205
References......Page 208
10.1 The Ediacaran world......Page 213
10.2 Preservational context......Page 214
10.3 Vendobionts as giant protozoans......Page 215
10.4 Kimberella as a stem-group mollusc......Page 218
10.5 Worm burrows......Page 222
10.6 Stability of ecosystems......Page 223
10.7 The parasite connection......Page 224
10.8 Conclusions......Page 227
References......Page 228
11.1 Introduction......Page 230
11.2 Collagen as a trait tying together metazoans......Page 231
11.3 The critical oxygen concentration criterion......Page 232
11.4 The Burgess Shale fauna: a radiation on rocky ground......Page 233
11.5 Accumulating evidence about snowball Earth......Page 235
11.6 North of 80......Page 236
References......Page 239
Part III Life in the Solar System?......Page 243
12.1 Introduction......Page 245
12.2 Mars today and the Viking search for life......Page 247
12.3 Search for second genesis......Page 249
12.3.1 Surface life......Page 250
12.3.2 Subsurface life......Page 253
12.3.4 Permafrost......Page 254
12.4 Detecting a second genesis on Mars......Page 255
References......Page 258
13.2 History......Page 261
13.3 Basic facts and considerations about DDSs......Page 263
13.4.1 The nature of photosynthesis and the microbial consortium......Page 270
13.4.2 The menace of ultraviolet irradiation......Page 271
13.4.3 The plausibility of liquid water and the challenge of low temperature......Page 273
13.5 Partial analogues on Earth......Page 275
13.6 Discussion and outlook......Page 277
References......Page 278
14.1 Introduction......Page 283
14.2 Analogies between Titan and the Earth......Page 284
14.3 A complex prebiotic-like chemistry......Page 291
14.4 Life on Titan?......Page 298
14.5 Conclusions......Page 300
Acknowledgements......Page 301
References......Page 302
15.1 Introduction: life beyond the habitable zone......Page 305
15.2.1 Global scale......Page 306
15.2.2.1 Ridges and cracks......Page 308
15.2.2.2 Tectonic displacement......Page 312
15.2.3 Chaotic terrain......Page 313
15.3 Tides......Page 315
15.3.1 Tidal torque: rotation effects......Page 317
15.3.2.1 Crack patterns......Page 318
15.3.2.2 Tidally active cracks......Page 319
15.3.3.1 Liquid water ocean with an ice crust......Page 323
15.3.3.2 Formation of chaotic terrain......Page 324
15.4 The permeable crust: conditions for a Europan biosphere......Page 325
References......Page 329
Index......Page 333