Michael Carroll How We Find Them, Communicate with Them, And
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Michael Carroll Earths of Distant Suns How We Find Them, Communicate with Them, and Maybe Even Travel There Earths of Distant Suns Michael Carroll Earths of Distant Suns How We Find Them, Communicate with Them, and Maybe Even Travel There Michael Carroll Fellow, International Association of Astronomical Artists Littleton , CO , USA ISBN 978-3-319-43963-1 ISBN 978-3-319-43964-8 (eBook) DOI 10.1007/978-3-319-43964-8 Library of Congress Control Number: 2016951720 © Springer International Publishing Switzerland 2017 Th is work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifi cally the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfi lms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Th e use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specifi c statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Th e publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. Printed on acid-free paper Th is Copernicus imprint is published by Springer Nature Th e registered company is Springer International Publishing AG Th e registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland Acknowledgments My thanks to Babak Tafreshi, talented astrophotographer, for the lovely view of the ALMA telescope. Babak, you let us hear the heavens sing! Nick Stevens played a key part in my understanding of interstellar ships and nuclear pulse propulsion. As if that weren’t enough, he shared his artistic masterpieces for the book! Steve Walker and Dorian Houser of the National Marine Mammal Foundation put up with my wacky questions with good humor. So did my buddy, “dolphin whisperer” Alan Lewis, who got them into it in the fi rst place. Th anks, Alan! Adrian Brown and Matthew Tiscareno played instrumental roles in my visit to SETI, as Chris McKay and Elisa Quintana did for my tour in NASA/Ames’ astrobiology wonderland. (Th anks for your offi ce, Chris!) Special commendation in the “Twilight Zone” category goes to premiere science writer Tina Saey, who made the same bizarre Star Trek/silicon life connection I did. Her article for Science News came out the week after I submitted this manu- script to my line editor. Good thinking, Tina! Th e fi rst reader and line/content editor extraordinaire Marilyn Flynn lent her magic. Finally, my gratitude to Caroline, who not only organized this literary mess but always lends structure and meaningful organization to my own wacky life. Love you, sweetie! v Contents 1 A Place Like Home 1 Th e Nebular Th eory of Planetary Formation 3 Th e Spiral Nebulae: Small and Close or Large and Distant? 4 Hello Out Th ere 6 Homes for ET 8 Someone to Talk To 9 2 Early Ideas and Lessons from Our Own Backyard 11 Moving Off the Center 11 Getting the Message Across 14 Th e Goldilocks Principle 17 Migrating Habitable Zones 19 Starring Roles 20 M Dwarfs 22 K-Type Stars 23 G-Type Stars 23 F-Type Stars 24 A-Type Stars 24 B-Type Stars 25 O-Type Stars 25 From Supernova to Black Holes 25 Habitable Zone Types 26 Past Lives of Our Earth 28 Th e Great Dyings 32 Earthlike Planets in Our Solar System 32 vii viii Contents Isn’t Th at Special? 36 A Really Big Habitable Zone? 39 Applying Lessons to Exo-Earths 39 3 Th e Search for and Discovery of Exoplanets 43 Finding Invisible Worlds 44 Direct Imaging 44 Radial Velocity 45 Timing Technique 47 Gravitational Microlensing 47 Autocorrelation Function Timescale Technique 49 Transits 49 Astrometry 52 Th e New Age of Discovery: Orbiting Observatories 55 51 Pegasi b…and Beyond 59 Chilled Giants 62 Earths, Mega-Earths, Sub-Neptunes and Super-Earths 63 4 Strange Solar System Architectures 67 Migrating Planets and the Search for Life 70 5 Zeroing in on Earth 2.0 75 Sub-Neptunes 75 Giant Planets and Earth-Moons 82 Other Super-Earth Types 82 Assorted Super-Earths 85 What’s the Forecast? 89 Zeroing in on Earth 2.0 94 Super-Habitable Places 97 Giants Inside the Habitable Zone: Th e Promise of the Moons 103 6 Looking for Life in All the Right Places 105 Life Based on What? 105 Life in Our Own Image 105 A Martian Invasion of a Diff erent Sort 107 Is Carbon the Only Game in Town? 114 Extreme Biomes 115 Under the Surface: Extremophiles Galore 116 Contents ix Europa 118 Enceladus: Europa on Steroids 121 Titan: Th e Alien World Next Door 124 Habitable Sub-Zones 129 Deep Sea Astrobiology Beyond Europa and Enceladus 129 Life with a Few Suns 132 In the Beginning, Life 133 Life’s ‘Tells’ in the Poker Game of Astrobiology 136 Finding Exo-Veggies 140 Th e Stars Are Out, But Is Anyone Home? 141 7 Could We Make Contact? 145 Fermi’s Paradox 146 Answer #1: A “Special” Rare Earth 146 Answer #2: Extinction 147 Answer #3: Not Interested, Th ank You! 147 Answer #4: We’ve Moved On 148 Answer #5: Sentient Suicide 148 Answer #6: Natural Quarantine 149 Answer #7: Cosmic Menagerie 149 Answer #8: Spectator Sport 150 Answer #9: Missed It By Th at Much 150 Using Waves 150 What Are the Odds? 152 Amoebas to Technology 157 Reaching Out 159 Transmission in a Bottle 164 Calls for Caution 168 Undertakings in the Search for Extraterrestrial Intelligence 169 A Diff erent Kind of Message 173 If I Could Talk With the Animals… 176 Assumptions 180 UFOs 181 Civilization’s Fingerprints Here and Beyond 184 8 Could We Visit Earths of Distant Suns? 193 Interstellar Vacations 195 Roadblock to Faster-Th an-Light Travel 198 Project Orion 200 x Contents Project Daedalus: To the Stars 202 Project Icarus 204 Non-Nuclear Options for Star Travel 206 Arrival 211 Interstellar Exploration’s Human Component 213 Generation Ships 215 Why Go? 217 9 First Contact: What Will It Mean? 219 Life’s Rich Pageantry 221 Visualizing World SETI 222 Why Bother? 224 SETI All Grown Up 225 Culture Clash 226 Dreams of Distant Earths 228 Engaging with the Others 228 Index 231 About th e Author Author/artist Michael Carroll has spent decades as a science journalist and even longer as an astronomical artist. He received the AAS Division of Planetary Science’s Jonathan Eberhart Award for the best planetary science feature article of 2012. He lectures extensively in concert with his various books and has done invited talks at science museums, aerospace facilities, and NASA centers. He has written articles and books on topics ranging from space to archeology. His articles and art have appeared in TIME , National Geographic , Scientifi c American , Smithsonian , Popular Science , Astronomy , Sky and Telescope , Astronomy Now (UK) , and a host of children’s books and mag- azines. Among his twenty-some books are Springer’s Living Among Giants: Exploring and Settling the Outer Solar System and his novel On the Shores of Titan’s Farthest Sea for Springer’s Science and Fiction series (2015). One of his paintings is on the surface of Mars—in digital form—aboard the Phoenix lander. Carroll is the 2006 recipient of the Lucien Rudaux Award for lifetime achievement in the astronomical arts. He is a fellow and founding member of the International Association of Astronomical Artists. xi 1 A Place Like Home But who shall dwell in these Worlds if they be inhabited? … Are we or they Lords of the World? … And how are all things made for man? —Johannes Kepler Our Solar System used to be a lonely, forlorn place. It spun along the Orion arm of the Milky Way Galaxy, trailing nine (yes, nine) planets, a flotilla of asteroids and comets, and one singular planet encrusted with something spe- cial: life. Beyond lay a myriad of stars, but did any of them have life forms? Our best telescopes could not resolve planets orbiting even the nearest of suns. Was it possible that Earth was alone, or at the very least a very, very rare case? Something within human nature causes us to yearn for community, or at least engenders a captivation with the other. Seth Shostak is the Senior Astronomer and Director of the SETI Research Institute. “I think we’re hard-wired to be interested in that possibility,” he surmises. “You go into any classroom, and say, ‘How many of you kids think there are aliens out there?’ Essentially all the hands go up. You can say that it’s because they’ve seen them on TV and in the movies. That’s true, but the reason that movies or TV por- tray these guys is that the audience accepts that idea. The reason that they’re interested in it is the same reason all kids are interested in dinosaurs. We’re hard-wired to be interested in predators. Anything with big teeth is of inter- est; you want to pay attention to what their habits are or you’re out of the gene pool.