by Lee Billings
She seemed puzzled by her sons’ preference for swashbuckling space opera rather than the breathtaking realities she and her colleagues were unearthing every day. “Do you have any idea why they are so fixated on Star Wars?” she asked after a time.
I didn’t, really, and mumbled about cultural archetypes in folklore and the “hero’s journey” of Joseph Campbell, the timeless fantasy of frontiers and creatures that, while exotic, still bore some comforting semblance of familiarity.
“Maybe,” she said, looking quizzical. “I don’t really know what it is, why people do what they do.” For a moment I lost the thread of our conversation. I was thinking of stories Seager had once told me, of Max pretending he was a visitor to Earth from an alien planet, and of Alex proclaiming he would become an astronaut to explore the Earth-like worlds his mother would discover. I remembered my own childhood, imagining I might someday visit a comet or be suddenly swept into the sky by a UFO to travel to another galaxy. Every child exists in a realm of infinite possibility, dreaming of other worlds, other lives—and of being singular and special enough to somehow reach and inhabit them. Whether it was unfulfilled potentials or harsh realities that made so many of those dreams fade at childhood’s end, I couldn’t say.
“I know I’m not going to live to see people travel to an exoplanet,” Seager was saying. “But I can still make the maps. What happens after that is beyond what I can really comment on. Could a civilization, if they wanted to, marshal their resources to go to the nearest stars? I think that is within our reach.” She excused herself to change a load of laundry, returning after a moment to talk about her new work in biosignatures.
Along with her collaborator William Bains, a UK-based biochemist, Seager was cooking up plausible alien worlds far different from Earth, trying to quantify what sorts of biospheres they might have and which sorts of biosignature gases could build up in their atmospheres. She and Bains wanted to assemble a catalog of potential varieties and scenarios, starting from the viewpoint that while Earth-like planets might be rare, planetary life was not.
She talked of anoxic “slime worlds,” with oceans covered in great mats and blooms of biomass pumping out methane or hydrogen sulfide, and of gas-blanketed greenhouse worlds far from their stars, where creatures gained energy not from splitting water but from combining hydrogen and nitrogen to make ammonia. On warm ocean planets sheathed in crushingly thick atmospheres, she envisioned life existing deep down in bubbling aerosols formed by the fluid, turbulent interface of sea and sky, twilight-blue worlds where organisms could effortlessly swim and fly between air and water intermixed at exactly equal densities. Figuring out how such things could manifest in a future TPF-style telescope required simulating not one planetary surface and atmosphere, but millions, each with a different set of thermodynamically plausible assumptions that would affect the generation and visibility of biosignatures. As usual for Seager’s work, some critics in the field seemed to think her new research was too futuristic to be useful—why go to such great lengths to clarify biosignatures for planetary environments that might not exist and that could only be observed using telescopes that might never be built?
“All this work is purely to make us ready for an eventual interpretation of unclear observations,” she parried, sipping her wine. “And some of this will start happening soon. First we’ll be able to look at some transiting super-Earths around nearby, quiet M-dwarfs, the ones with puffy, extended atmospheres that [the James Webb Space Telescope] and maybe even telescopes on the ground will be able to probe. But after that we won’t have infinite chances to find our Earth twin. Anything launched in our lifetimes will probably only be able to look at the nearest hundred stars or so, and that’s all we’ll have. So if we don’t have any Earth twins to survey in that space, how will we ever recognize any biosignature gases? Well, maybe we won’t—unless we do this sort of extensive first-principles analysis. We could be very humbled by our first glimpses of super-Earth atmospheres.”
I noted that she had forged her career out of being ahead of the curve, looking farther over the horizon than her peers. What did she think the future held? With the dream of a TPF deferred, what would sustain the exoplanet boom in the interim? Maybe after two decades of wild expansion, I offered, the field was on the verge of a dot-com–style crash.
Seager took a longer sip of wine, and rolled the glass stem between her fingers, thinking. “This really crystallized for me at the Next 40 Years [conference],” she began. “This field was built by rogue pioneers. It’s a selection effect—you wouldn’t have gotten into this if you weren’t tough and belligerent and willing to take big risks and have high standards. Now the quality control is decreasing because so many people are flowing in. There are a ton of people who now appear to all be doing basically the same thing, with minor incremental variations. Everyone agrees we should map the nearby stars, but we don’t have unity on the best approach.” She bemoaned what she saw as a growing excess of sloppy theoretical work and observational results that added little to the field. “How many more transiting hot Jupiters do we really need?” she wondered. “Maybe we need more, but maybe we don’t. I’m not the best to say.”
But the lack of unity had its advantages, she went on. “Exoplanets are a bit like a dot-com bubble, yeah. But this will be like a hundred-year bubble, something that lasts a long time. It’s always been true in astronomy that anytime you have a new technology and a new telescope, a new field opens up. It happened with high-precision spectrographs and radial velocity. It’s happening with Kepler and transits. I see it like waves. You had an RV wave, it’s now playing a supporting role, but it may have a resurgence later if most stars have Earths. Right now you have Kepler transits driving a wave. You’ll have other waves later. The direct-imaging wave is coming. TPF is coming. They all overlap, but they all started at different times, so they have different phases. . . . The bubble will last because you can’t have everything at the same time. Maybe if we had billions of dollars and did them all at once it would burn out. Because of the graduated opening of things, it’s going to go on. Even once we find and directly image potential Earths, people will want to keep getting better resolution of their atmospheres and surfaces. But it won’t last forever, it’s true.”
She finished her wine and checked the time. It was past 11:00 p.m., and I needed to catch the train back to Cambridge. Before I left, though, she said she wanted to show me something. We walked upstairs, past Max and Alex sleeping in their beds, and into a small study with bookshelves and a couch. She opened a nearby closet and retrieved several framed, yellowing photographs, laying them on the couch for display. Most were of Wevrick: pulling a canoe through rushing water, bestride a boulder on a massive esker’s summit, haggard and dignified after a long day’s hike. There he was, gazing into Seager’s eyes as they embraced on their wedding day. He wore a black suit jacket and tie, and she was all in white, with pale flowers in her hair. Others showed plumes of undulating black smoke smearing out the blue sky above a shoreline of charred, dead trees, and sunlight shining off mist above pounding rapids.
“I used to be really into photography,” Seager softly remarked. “On our trips, Mike would cook the food, and I would take the pictures. . . . I don’t try to focus on my husband’s death. But, you know, he died, and it was a major blow. It’s having a huge ripple effect. Now I’m trying to live more purposefully. My children, my mentees, my students. I’m trying harder than ever before to motivate people to cut through the clutter and reach their dreams—myself included.”
• • •
I met Seager in her office the next morning and accompanied her into the late afternoon through a blur of meetings, phone calls, and classes. Every hour a different part of her brain pivoted to a new set of problems, smoothly slewing from advising postdocs about their exoplanet research projects, to discussing the finer points of satellite thermal control with her graduate group, to giving project-management advice to undergraduate engineering students. By t
he evening I was exhausted, but Seager seemed inexhaustible—we separated for a couple of hours for her to take the qualifying exams for a ham radio license, which she wanted in relation to her interest in communications satellites. Dinner followed, sushi at a campus restaurant. Before parting ways, we backtracked through the night to the Green Building and took the elevator up to her seventeenth-floor office, where she had forgotten a bag. In the window of the unlit room, the city lights glinted off the dark rippling river, and for a moment we seemed to be floating in deep space, looking down on a galaxy’s countless glittering stars. She looked up from rummaging around her desk and paused, bag in hand, entranced by the view.
“I love the skyline,” she said, her back to me. “It gets me every time. The river. The sky. The light. It’s a big part of my life, actually, the view and how it changes. How night falls. I look out and think about all the people, how the world fits together, the continuum of light. Day fades into night and then night fades back into day. Nature sets the path, but we do have some control. We’re the product of millions of years of evolution, but we don’t have any time to waste. That’s what I’ve learned from death.” Her voice broke and quavered, then through tears regained its strength. “Death made me realize how worthless most things are, yeah? Nothing else is meaningful; it supersedes everything. I have lost tolerance for things without meaning. There is no time for them. Does that make sense?”
In the darkness, a memory of a framed photograph she had shown me the night before swam unbidden to my mind. It was a rare shot snapped by Wevrick, taken from a height. A vast expanse of yellow grass and stunted trees swept out to the shores of a nameless lake, which stretched all the way to a treeless esker horizon. In the foreground, a lone point-like figure bent under an arc of red, casting a long shadow in the golden light of the Sun. It was Seager, steadfastly hauling the heavy canoe through the inhospitable terrain of the transition zone. The low-resolution photo did not convey whether the difficult portage was nearing its end or only just beginning. In the distance, the Barren Lands rolled on.
This book was a long time coming, and a long list of people helped it along the way. I am thankful to Courtney Young for her belief in me, and to Emily Angell and Annie Gottlieb for sharpening my prose with their editorial oversight. My agent, Peter Tallack, has provided critical support from start to finish, and deserves much praise.
I am indebted to several members of my family for their moral and financial support. Were it not for the generosity of my parents, Mike and Pam Billings, and my grandparents, Bruce and Jo Hannaford, this book would not exist. My sister Carolyn and her husband Matt Tapie provided indulgent conversations and a roof over my head on some research trips. Most of all, I wish to thank my wife, Melissa Lherisson Billings, for her unwavering support, patience, and love.
My thanks to Adam Bly and the Seed Media Group editorial team for enabling some of my earliest encounters with a few key sources. Similarly, by inviting me to attend several of its annual symposia, the Miller Institute for Basic Research in Science at the University of California, Berkeley, proved invaluable for incubating portions of this book. I am particularly grateful to Kathryn Day, Raymond Jeanloz, and Michael Manga for their kindness to me during my visits. Maggie Koerth-Baker, the science editor of Boingboing.net, was also instrumental in helping this project get off the ground in its formative stages. Nadia Drake deserves a very special thanks for arranging my meeting with her father.
For their friendship, advice, and encouragement, I must recognize: Evan Lerner, T. J. Kelleher, Paul Gilster, Joshua Roebke, Eric Weinstein, Jon Bardin, Ken Chang, Andrew Fullerton, Christopher Xu, Josh Chambers, George Musser, Carl Zimmer, and E.J. of Nevada County.
Over the years, a great many people generously answered my questions in ways that directly or indirectly informed this book. That said, any errors in this volume are entirely my own. I owe the following sources many thanks for their time and expertise:
Roger Angel, Guillem Anglada-Escudé, Mike Arthur, William Bains, Natalie Batalha, Charles Beichman, David Bennett, Michael Bolte, Xavier Bonfils, Alan Boss, John Casani, Webster Cash, John Chambers, Phil Chang, David Charbonneau, Nick Cowan, Paul Davies, Drake Deming, Frank Drake, Alan Dressler, Michael Endl, Debra Fischer, Kathryn Flanagan, Eric Ford, Colin Goldblatt, Mark Goughan, Jeff Greason, John Grunsfeld, Javiera Guedes, Olivier Guyon, Robin Hanson, Tori Hoehler, Andrew Howard, Jeremy Kasdin, Jim and Sharon Kasting, Heather Knutson, Antoine Labeyrie, David Latham, Greg Laughlin, Doug Lin, Jonathan Lunine, Kevin McCartney, Claudio Maccone, Bruce Macintosh, Geoff Marcy, John Mather, Greg Matloff, Michel Mayor, Vikki Meadows, Jon Morse, Matt Mountain, Phil Nutzman, Ben Oppenheimer, Bob Owen, Ron Polidan, Marc Postman, Sean Raymond, Dimitar Sasselov, Jean Schneider, Sara Seager, Michael Shao, Seth Shostak, Rudy Slingerland, Chris Smith, Rémi Soummer, David Spergel, Alan Stern, Peter Stockman, Jill Tarter, Philippe Thébault, Wes Traub, Michael Turner, Stéphane Udry, Steve Vogt, Jim Walker, Bernie Walp, Andrew Youdin, and Kevin Zahnle.
CHAPTER 1: Looking for Longevity
Ronald N. Bracewell, The Galactic Club: Intelligent Life in Outer Space (San Francisco: W. H. Freeman, 1974).
Giuseppe Cocconi and Philip Morrison, “Searching for Interstellar Communications,” Nature, vol. 184 (1959), pp. 844–46.
Frank Drake and Dava Sobel, Is Anyone Out There? The Scientific Search for Extraterrestrial Intelligence (New York: Delacorte Press, 1992). I quote Drake from page 27.
Stanislaw Lem, Summa Technologiae (Minneapolis: University of Minnesota Press, 2013; first edition, 1964). Translated by Joanna Zylinska, this is the first complete English translation of Lem’s prescient classic on cosmic evolution.
J. P. T. Pearman, “Extraterrestrial Intelligent Life and Interstellar Communication: An Informal Discussion,” in Interstellar Communication, A. G. W. Cameron, ed. (New York: W. A. Benjamin, 1963), pp. 287–93.
Iosif Shklovskii and Carl Sagan, Intelligent Life in the Universe (San Francisco: Holden-Day, 1966).
Walter Sullivan, We Are Not Alone: The Continuing Search for Extraterrestrial Intelligence, rev. ed. (New York: Dutton, 1993).
Otto Struve, “Proposal for a Project of High-Precision Stellar Radial Velocity Work,” The Observatory, vol. 72 (1952), pp. 199–200.
CHAPTER 2: Drake’s Orchids
J. D. Bernal, The World, the Flesh, and the Devil: An Enquiry into the Future of the Three Enemies of the Rational Soul (London: Kegan Paul, Trench, Trübner, 1929).
Paul Davies, The Eerie Silence: Renewing Our Search for Alien Intelligence (New York: Houghton Mifflin Harcourt, 2010).
Frank Drake, “Stars as Gravitational Lenses,” in Bioastronomy—The Next Steps, G. Marx, ed., Astrophysics and Space Science Library, vol. 144 (Dordrecht: Kluwer Academic Publishers, 1988), pp. 391–94.
Frank Drake and Dava Sobel, Is Anyone Out There? The Scientific Search for Extraterrestrial Intelligence (New York: Delacorte Press, 1992). Drake’s calculation of how many boxes of corn flakes the Arecibo Observatory radio dish could hold appears on pages 73–74.
Von R. Eshleman, “Gravitational Lens of the Sun: Its Potential for Observations and Communications Over Interstellar Distances,” Science, vol. 205 (1979), pp. 1133–35.
Paul Gilster, Centauri Dreams: Imagining and Planning Interstellar Exploration (New York: Springer, 2004).
Hans Moravec, Mind Children: The Future of Robot and Human Intelligence (Cambridge, MA: Harvard University Press, 1988).
Peter D. Ward and Donald Brownlee, Rare Earth: Why Complex Life Is Uncommon in the Universe (New York: Springer, 2000).
CHAPTER 3: A Fractured Empire
Guillem Anglada-Escudé et al., “A Planetary System around the Nearby M Dwarf GJ 667C with At Least One Super-Earth in its Habitable Zone,” The Astrophysical Journal Letters, vol. 751 (2012), pp. L16–.
Lee Billings, “G is for Goldilocks,” Seedmagazine.com, October 1, 2010. http://seedmagazine.com/content/article/g_is_for_goldilocks/.
Xavier Bonfils et al., “T
he HARPS Search for Southern Extra-solar Planets XXXI. The M-dwarf Sample,” Astronomy & Astrophysics, vol. 549 (2013), pp. 109–.
Alan Boss, The Crowded Universe: The Search for Living Planets (New York: Basic Books, 2009).
Xavier Delfosse et al., “The HARPS Search for Southern Extra-solar Planets XXXV. Super-Earths around the M-dwarf Neighbors Gl433 and Gl667C,” arXiv preprint (2012).
Bruce Dorminey, Distant Wanderers: The Search for Planets Beyond the Solar System (New York: Springer, 2001).
Thierry Forveille et al., “The HARPS Search for Southern Extra-solar Planets XXXII. Only 4 planets in the Gl~581 system,” arXiv preprint (2011).
Philip C. Gregory, “Bayesian Re-analysis of the Gliese 581 Exoplanet System,” arXiv e-print (2011).
Ray Jayawardhana, Strange New Worlds: The Search for Alien Planets and Life Beyond Our Solar System (Princeton: Princeton University Press, 2011).
Marc Kaufman, First Contact: Scientific Breakthroughs in the Hunt for Life Beyond Earth (New York: Simon & Schuster, 2011).
Michael D. Lemonick, Other Worlds: The Search for Life in the Universe (New York: Simon & Schuster, 1998).
Tim Stephens, “Newly discovered planet may be first truly habitable exoplanet,” University of California, Santa Cruz, Newscenter, September 29, 2010. http://news.ucsc.edu/2010/09/planet.html.
Otto Struve, “Astronomers in Turmoil,” Physics Today, vol. 13 (1960), p. 18.
Mikko Tuomi, “Bayesian Re-analysis of the Radial Velocities of Gliese 581. Evidence in Favour of Only Four Planetary Companions,” arXiv preprint (2011).
