Titan: Exploring an Earthlike World

Contents......Page 6
Prologue......Page 14
Foreword......Page 18
1.1 Early History......Page 20
1.2 Titan in Mythology......Page 24
1.3 Space Exploration of the Solar System......Page 27
1.4 The 20th Century, Before Voyager......Page 32
2.1 Space Missions to the Saturnian System......Page 35
2.2 Voyager Observations of Titan......Page 39
2.4 Vertical Temperature Structure......Page 41
2.5 Energy Balance and the Temperature Profile in the Thermosphere......Page 45
2.6 Atmospheric Composition......Page 47
2.7 Photochemistry......Page 50
2.8 Cloud and Haze Properties......Page 53
2.9 Speculations on the Surface and Landscape of Titan from Voyager......Page 54
2.10 The Aftermath of Voyager......Page 55
3.2 Space Observatories......Page 57
3.2.1 Hubble Space Telescope......Page 58
3.2.2 The JamesWebb Space Telescope......Page 59
3.2.3 Infrared Space Observatory......Page 60
3.3.1 Mauna Kea Observatories......Page 63
3.3.2 The European Southern Observatories......Page 65
3.3.3 The University of Arizona and Steward Observatory Telescopes......Page 67
3.3.4.1 IRAM......Page 68
3.3.4.2 The Very Large Array (VLA)......Page 69
3.3.4.5 The Square Kilometre Array (SKA)......Page 70
3.4.1 Occultations of Titan......Page 71
3.4.2 The Radar Search for Oceans, Seas or Lakes......Page 73
3.4.3 Spectroscopic Measurements of Titan’s Albedo......Page 76
3.4.4 Imaging Titan’s Atmosphere in the Near-Infrared......Page 83
3.4.5 Imaging the Surface......Page 85
3.5 Ground-Based Observations and Cassini–Huygens......Page 90
4.1 Introduction......Page 91
4.2 The Spacecraft and its Systems......Page 92
4.3 Scientific Objectives......Page 96
4.4 The Long History of the Cassini–Huygens Mission......Page 98
4.5 Departure for the Saturnian System......Page 101
4.6 Journey to Saturn and Orbit Insertion......Page 103
4.7 Huygens Descends onto Titan......Page 104
4.8.1 The Scientific Instruments on the Orbiter......Page 108
4.8.2 The Scientific Instruments on the Probe......Page 118
4.9 Touring the Saturnian System......Page 126
4.9.1 Observations of Saturn......Page 7
4.9.2 The Icy Satellites, and Saturn’s Rings......Page 128
4.9.3 Saturn’s Magnetosphere and Titan......Page 131
4.10 Being Involved: Scientists and Instrument Providers......Page 132
4.11 Reaping the Benefits......Page 134
Colour Plates......Page 136
5.1.1 Atmospheric Pressure Profile......Page 148
5.1.2 Atmospheric Thermal Structure......Page 150
5.1.3 Troposphere......Page 152
5.1.4 Stratosphere......Page 154
5.1.7 Exosphere......Page 155
5.2.2 Energy Balance and Surface Temperature......Page 156
5.2.3 Model Temperature Profile......Page 157
5.2.4 Radiative Equilibrium Temperature Profile......Page 158
5.3 Remote Atmospheric Temperature Sounding......Page 160
5.4 Titan’s Ionosphere and its Interaction with the Magnetosphere of Saturn......Page 163
5.5 Climate Change on Titan......Page 166
6.1 Titan’s Chemical Composition......Page 169
6.2 The Bulk Composition of the Atmosphere......Page 173
6.3 Ionospheric Chemistry......Page 174
6.4 Trace Constituents in the Neutral Atmosphere......Page 176
6.4.1 Stratospheric Composition Measurements with Cassini......Page 179
6.4.1.1 Hydrocarbons......Page 181
6.4.1.2 Nitriles......Page 185
6.4.1.4 Deuterium: CH3D and D/H Ratio......Page 192
6.4.2 Vertical Distributions......Page 194
6.4.3 Spatial Variations......Page 196
6.4.4 Temporal Variations of the Trace Constituents......Page 199
6.5 Photochemistry......Page 200
6.5.1 Hydrocarbons......Page 204
6.5.2 Nitriles......Page 207
6.5.3 Oxygen Compounds......Page 208
6.5.4 Condensation Efficiencies......Page 211
6.5.5 Aerosol Production......Page 212
7.1 Introduction and Overview......Page 213
7.2 Terrestrial Clouds and Precipitation......Page 216
7.3 Visible Aspects of Titan’s Haze......Page 217
7.4 Size and Vertical Distribution of the Haze Particles......Page 220
7.4.1 Haze Vertical Profiles......Page 222
7.4.2 Haze Opacity Spatial Variations......Page 224
7.5 Tropospheric Condensate Clouds......Page 225
7.6 Thermal and Dynamical Interactions with the Haze......Page 229
7.7 Observational Evidence on the Aerosol Composition......Page 232
7.8 Laboratory Simulations of Haze Materials......Page 236
7.8.1 Chemical Composition of Tholins......Page 237
7.8.2 Optical Properties of Tholins......Page 240
7.9.1 Organic Haze Production......Page 242
7.9.2 Fractal Models and Scattering Properties of the Haze......Page 246
7.10 Discussion and Conclusion......Page 248
8.1 Introduction......Page 250
8.2 Dynamics of Planetary Atmospheres......Page 251
8.3 Titan’s General Circulation......Page 256
8.4 Zonal Motions......Page 257
8.5 The Meridional Circulation......Page 262
8.5.1 The Hemispherical Asymmetry......Page 263
8.5.2 The Polar Vortex......Page 264
8.6 Vertical Motions......Page 266
8.7 Waves, Tides and Turbulence......Page 269
8.8 TheWeather Near the Surface......Page 270
8.9 Does Lightning Occur on Titan?......Page 274
9.1 Introduction......Page 277
9.2 Remote Sensing of the Surface......Page 278
9.3 Huygens Takes a Plunge......Page 280
9.4 Naming Distant New Places......Page 285
9.5.1 Albedo Variations......Page 288
9.5.2 Craters......Page 289
9.5.3 Mountains and Volcanoes......Page 292
9.5.4 Dunes......Page 293
9.5.5 Lakes......Page 294
9.6 The Nature and Composition of the Surface......Page 296
9.7 The Interior of Titan......Page 300
10.1 Introduction......Page 305
10.2 Relations Among Solar System Bodies......Page 306
10.2.1 The Formation of the Solar System......Page 308
10.2.2 The Terrestrial Planets and Titan......Page 309
10.2.3 Titan and the Outer Planets......Page 316
10.2.4 Titan and the Other Saturnian Satellites......Page 323
10.2.4.1 Iapetus......Page 327
10.2.4.2 Rhea......Page 329
10.2.4.4 Tethys and Mimas......Page 330
10.2.4.6 Enceladus......Page 335
10.2.4.7 Smaller Satellites......Page 336
10.2.6 Nitrogen Atmospheres in the Outer Solar System......Page 337
10.3 Titan’s Origin and Evolution......Page 340
10.3.1 Evolutionary Models for Titan’s Atmosphere......Page 343
10.3.2.1 Nitrogen......Page 344
10.3.2.2 Methane......Page 345
10.3.2.3 Water and Other Oxygen Compounds......Page 346
10.3.2.4 Isotopic Ratios......Page 347
10.4 Titan and Life......Page 348
10.5 Open Questions......Page 349
11.1 Returning to Titan......Page 351
11.2 Titan as a Target of Astrobiological Interest......Page 353
11.3 Science Drivers and Measurements Needed......Page 354
11.4 Advanced Titan Mission Concepts......Page 356
11.6 Mission Architecture and Design......Page 358
11.7 Getting to Titan: Launch and Propulsion......Page 359
11.8 The Voyage of the Titania......Page 360
11.9 Explorers on Titan......Page 362
Glossary and Acronyms......Page 369
References and Bibliography......Page 377
Index......Page 410