Micrometeorites and the Mysteries of Our Origins (eBook)

Preface 6
Acknowledgements 9
Contents 12
PART I Staging the Cosmic Theater 18
1 Solar System Bodies and Primitiveness 19
2 The Power of Wetherill’s Friend, Jupiter 26
3 The Earth–Moon System 28
3 The Earth–Moon System in a Gigantic Cosmic Firing Range 28
3.1 The Artistry of Radiochronometers 28
3.2 Formation of the Moon by the Last Planetary 29
Embryo Merging the Earth 29
3.3 From Highly Cratered Highlands 31
to Sparsely Cratered Mare on the Moon 31
3.4 Reprocessing of Planetary Materials in Regoliths 34
3.5 Scavenging of Highly Siderophile Elements 37
During Large Impacts 37
4 A Microscopic Suspect for the Formation of the Earth’s Atmosphere 39
4.1 Beware of Visible and Invisible Shooting Stars 39
4.2 A New Star in the Cosmic Theater 41
4.3 A Giant Storm of Cometary Shooting Stars? 42
4.4 A Decisive Rendez-Vous 44
with Antarctic Micrometeorites 44
PART II “Primitive” Extraterrestrial Matter on the Earth 45
5 The Space Collector Earth 46
5.1 Dark Stones in Cold and Hot Deserts 46
5.2 Micrometeorites in the Stratosphere 49
and Deep Sea Sediments 49
5.3 Micrometeorites on the Greenland 54
and Antarctic Ice Sheets 54
5.4 Moving to Central Antarctica 66
to Avoid Cryogenic Weathering 66
6 Classification of Meteorites and Micrometeorites 69
6.1 Meteorites 69
6.2 The Hunt for Primitiveness 74
6.3 The Deceptively Simple Classi.cation 76
of Antarctic Micrometeorites 76
6.4 Beware of Chemical, Mineralogical 82
and Isotopic Chaos 82
7 The Major Contribution of Micrometeorites to the Delivery of Hydrous–Carbonaceous Material to the Earth 87
PART III Formation of the Post-Lunar Earth’s Atmosphere 93
8 The Inadequacy of Previous Scenarios 94
8.1 Competing Scenarios 94
8.2 Volcanic Outgassing, Accretion of Nebular Gases 95
and Cometary Impacts 95
8.3 A Wrong Neon for the Giant 96
Asteroid? 96
9 A Prime Suspect for the Formation of the Atmosphere 99
9.1 Concentrations of Volatiles 99
in Antarctic Micrometeorites 99
9.2 The Micrometeorite Purity 102
of the Early Earth’s Atmosphere 102
10 Formation of the Post-lunar Atmosphere 106
10.1 The Invariant Composition of Micrometeorites 107
with Time 107
10.2 An Accretion Formula Born with the Moon 109
10.3 Two Estimates of 110
from Neon and Nitrogen 110
in the Atmosphere 110
10.4 A Third Independent Estimate of 111
from the Lunar Impact Record 111
10.5 An Astonishingly Good Fit Between Predictions 112
and Observations 112
10.6 Controversies about Pre-atmospheric Solar Neon 114
and Nitrogen in Micrometeorites 114
11 The Mysterious Fate of Early Micrometeoritic Oxygen 116
PART IV Exobiology with Unmelted Micrometeorites 118
12 The Birth of Life on the Early Earth 119
12.1 The Pioneers 120
12.2 Discontinuous Bursts of Early Life Prior 122
to about 4.2 Gyr Ago? 122
13 Microscopic Chondritic Chemical Reactors 124
13.1 A Hydrous-Carbonaceous Chondritic Composition 124
13.2 A Shielding within a Thin Magnetite Shell 128
13.3 A New Cosmochromatograph 130
and Catalyst, Ferrihydrite 130
14 Radiation Reprocessing of Organics by Energetic Ions in Space 137
14.1 Reprocessing of Meteorites 137
and Sporadic Micrometeorites 137
14.2 Pristine Organics in Shower Micrometeorites: 140
Beware of Analytical Techniques! 140
PART V Micrometeorite Ashes in Exobiology and Early Climatology 144
15 First Hints 145
16 Micrometeorite and Minimeteorite Ashes in Prebiotic Chemistry 146
16.1 High Input Rates of SO2 and CO2 to Feed 146
the Early Submarine Hydrothermal System 146
16.2 Kerogen in Shooting Star Chemistry 148
16.3 Dreaming in Sandy Deserts about Persistent 153
Meteor Trains in the Hadean Night Sky 153
16.4 Meteors of cm-size Minimeteorites 158
16.5 Oligoelements in Precambrian Oceans 160
17 Micrometeorites in the Post-lunar Greenhouse Effect 162
17.1 The Major Role of the Moon-forming Impact 162
17.2 Early Climatic E.ects 163
of the Post-lunar Thermospheric Cocoon 163
PART VI Micrometeorites in Comparative Planetology 166
18 Micrometeoritic Iridium in the Earth’s Mantle with the Hartmann Conjuncture 168
19 Micrometeoritic Neon on the Earth 170
19.1 Earlier Suggestions About Micrometeoritic Neon 170
in the Earth’s Mantle 170
19.2 A Unique Isotopic Signature of Neon 172
in Antarctic Micrometeorites 172
19.3 The Severe Solar Wind Sunburns 175
of Micrometeorites 175
19.4 Two Relicts of Early Micrometeoritic Neon 185
in the Present-Day Atmosphere 185
19.5 A Relict of Micrometeoritic Neon 186
in the Upper Mantle 186
20 The Micrometeoritic Purity of the Atmosphere and Early Earth’s Processes 188
20.1 A Finely Tuned Occurrence 188
of Early Earth’s Processes 188
20.2 The Right Cleaning Impact at the Right Time 189
21 Extrapolation of EMMA to the Moon and Mars 192
21.1 The Lunar Iridium Puzzle 192
21.2 EMMA with Spirit and Opportunity on Mars 198
21.3 A Hard Time for EMMA on the Moon and Mars 204
PART VII Parent Bodies of Micrometeorites and Early Solar System Processes 206
22 The Hunt for Micrometeorites Parent Bodies 207
22.1 Conventional Views: a Small Abundance 207
of Cometary Micrometeorites 207
22.2 The Inadequacy of Previous Simulations 209
of Atmospheric Entry 209
22.3 Additional Evidence for a Cometary Origin 211
of Micrometeorites 211
22.4 Search for Leonid Cometary Micrometeorites 216
from the Cold 216
23 No Consensus About the Early History of the Lunar Impact Flux 219
23.1 The LHBomb in the Debris-Disk Sun 219
23.2 The Fossil Record 221
23.3 Con.icting Conjunctures 224
23.4 Hard Time on the Conjunctures 227
23.5 Regoliths and Old Australian Zircons 234
24 Micrometeorites and Early Solar System Processes 240
24.1 A Gigantic Conveyor Belt System of Dust Grains 240
in the Solar Nebula 240
24.2 The Invariant Composition 243
of the Micrometeorite Flux 243
24.3 The Lost Record of High Dust Collision Rates 244
in the Early Debris Disk 244
PART VIII Challenges Ahead 245
25 Relationships with CM-type Chondrites 246
25.1 The Primitive Chondritic Chemical Composition 246
25.2 Anhydrous and Hydrous Silicates 249
25.3 A Broad Distribution 251
of Short Galactic Cosmic Rays Exposure Ages 251
25.4 Major Di.erences between AMMs 252
and CM Chondrites 252
26 The Enigmatic Di.erences between Stratospheric and Antarctic Micrometeorites 253
26.1 Chemical Composition and Mineralogy of SMMs 253
26.2 Di.erences with the Cap-Prudhomme AMMs 255
26.3 The Isotopic Puzzle 257
27 The World of Hidden Biases: From Collection to Sample Processing 259
27.1 Biases in Greenland and Antarctica 259
27.2 A Preferential Skimming 262
of Fine-grained Primitive Dust in the Stratosphere? 262
28 Stardust Attacks in Bob Laboratory for Space Sciences 266
29 Challenges Still to Be Appropriately Addressed 273
29.1 The Opaque Mystery of the Heavy Noble Gases 273
29.2 Japanese Doubts about the Physics 275
of the Giant Moon-forming Impact 275
29.3 The New Hf-W Chronology Invalidates 276
the Timing of EMMA? 276
29.4 The Need for a Strong EUV Heating 277
of the Early Thermosphere Invalidates EMMA? 277
29.5 Light or Heavy Micrometeorite SMOW Water 278
29.6 Nitrogen on Trial 281
29.7 Further Search for a Micrometeorite 285
Contamination of Mars and Venus 285
PART IX Science and Fiction 287
30 Summary 288
Epilogue: The Birth of Micrometeoritics 295
References 303
Index 331