by Adam Frank
For a scientist, it is always a little frightening to write about topics that are not squarely in the domain of your research specialty. For me, this included not only sciences like atmospheric chemistry, but also the amazing history of the discoveries I wanted to explore in the book. I bear full responsibility for any mistakes made in the text. In trying to get the story right, though, I was helped by many scientists who were generous with their time. In particular, my collaborator Woody Sullivan at the University of Washington provided many fine insights into the manuscript. My gratitude to him runs very deep. Jason Wright of Penn State gave an early version of the book a thorough and deep reading. Not only did he make the book more accurate, but he also drove me to think more deeply about a number of topics on exo-civilizations. Jill Tarter not only gave me a number of great interviews, but also provided excellent feedback on the manuscript. I am equally grateful to Donald Canfield, both for interviews on atmospheric chemistry and his review of the chapter on Earth science. James Kasting of Penn State and Lee Murray of the University of Rochester provided excellent feedback on the climate and Earth science sections as well. Robert Haberle was generous with his time in explaining the history of Mars climate modeling and reviewing the chapter on solar system exploration.
I am also grateful to Soren Gregersen, whom I bothered a number of times to tell me his stories of being a Boy Scout and living out on the Greenland ice sheet with the US military at Camp Century. I am equally grateful to Natalie Batalha and Bill Borucki for giving me their time for interviews.
There are also many people I have to thank just for their intellectual companionship. Robert Pincus and Paul Green are always at the top of the list on any topic for me. My PhD advisor and continuing collaborator Bruce Balick has always been a source of good advice and ideas. I also had many excellent conversations with my colleagues at the University of Rochester: Dan Watson, Eric Blackman, Alice Quillen, Eric Mamejek, Judy Pipher, and Bill Forrest. Also, I must thank my collaborators on the work described in this book: Woody Sullivan, Marina Alberti, Axel Kleidon, and Jonathan Carroll-Nellenback. Ongoing discussions with Evan Thompson were also fun and helpful. Writing on these topics for both NPR and the New York Times gave me a first chance to cast the ideas in non-scientific language. I am very grateful to Jamie Reyerson at the Times, as well as Meghan Sullivan and Justine Kenin at NPR.
Finally, I am particularly grateful for my NPR blog co-founder, collaborator, and friend Marcelo Gleiser, who provided the opportunity to spend time at the Institute for Cross Disciplinary Engagement at Dartmouth, where some of this book was written. Thank you, Marcelo.
Finally, I must thank my children, Sadie and Harrison, as well as my brother-in-law, Hendrik Helmer, for making me laugh . . . a lot. And always, always, always, I thank the stars for my wife, Alana Cahoon, without whom none of this would matter.
NOTES
INTRODUCTION: THE PROJECT AND THE PLANET
1.John D. Durand, “Historical Estimates of World Population: An Evaluation,” PSC Analytical and Technical Reports, no. 10 (1974): table 2.
2.Department of Economic and Social Affairs, Population Division, The World at Six Billion (New York: United Nations Secretariat, 1999), http://www.un.org/esa/population/publications/sixbillion/sixbillion.htm.
3.Paul Mann, Lisa Gahagan, and Mark B. Gordon, “Tectonic Setting of the World’s Giant Oil and Gas Fields,” in Giant Oil and Gas Fields of the Decade, 1990–1999, ed. Michel T. Halbouty (Tulsa, OK: American Association of Petroleum Geologists, 2014).
4.Department of Economic Affairs, Population Division, World Population Prospects: Key Findings and Advance Tables, 2015 Revision (New York: United Nations, 2015), https://esa.un.org/unpd/wpp/Publications/Files/Key_Findings_WPP_2015.pdf.
5.International Air Transport Association, 2012 Annual Review, June 2012.
6.Lynn Margulis, “Gaia Is a Tough Bitch,” in The Third Culture: Beyond the Scientific Revolution, ed. John Brockman (New York: Simon and Schuster, 1995).
7.Kim Stanley Robinson, Aurora (New York: Orbit, 2015).
8.University of Zurich, “Great Oxidation Event: More Oxygen through Multicellularity,” ScienceDaily, January 17, 2013, www.sciencedaily.com/releases/2013/01/130117084856.htm.
9.European Space Agency, “Greenhouse Effect, Clouds and Winds,” Venus Express, http://www.esa.int/Our_Activities/Space_Science/Venus_Express/Greenhouse_effect_clouds_and_winds.
10.V.-P. Kostama, M. A. Kreslavsky, and J. W. Head, “Recent High-Latitude Icy Mantle in the Northern Plains of Mars: Characteristics and Ages of Emplacement,” Geophysical Research Letters 33, no. 11 (2006), doi: 10.1029/2006GL025946, and NASA Jet Propulsion Laboratory, “Mars Ice Deposit Holds as Much Water as Lake Superior,” news release, November 22, 2016, https://www.jpl.nasa.gov/news/news.php?release=2016-299.
11.Joe Mason and Michael Buckley, “Cassini Finds Hydrocarbon Rains May Fill Titan Lakes,” Cassini Imaging Central Laboratory for Operations, January 29, 2009, http://ciclops.org/view.php?id=5471&js=1. The liquids on Titan include components of gasoline.
12.Colin N. Waters et al. “The Anthropocene Is Functionally and Stratigraphically Distinct from the Holocene,” Science 351, no. 6269 (January 8, 2016), http://science.sciencemag.org/content/351/6269/aad2622.
13.Dale Jamieson, Reason in a Dark Time (New York: Oxford University Press, 2014).
14.NASA Exoplanet Science Institute, “Exoplanet and Candidate Statistics,” NASA Exoplanet Archive, https://exoplanetarchive.ipac.caltech.edu/docs/counts_detail.html.
CHAPTER 1: THE ALIEN EQUATION
1.C. P. Snow, The Physicists (Boston: Little Brown, 1981).
2.Alan Lightman, A Sense of the Mysterious: Science and the Human Spirit (New York: Vintage, 2006).
3.Eric M. Jones, Where Is Everybody?: An Account of Fermi’s Question (Los Alamos, NM: Los Alamos National Laboratory, 1985), https://www.osti.gov/accomplishments/documents/fullText/ACC0055.pdf.
4.Jones, Where Is Everybody?: 3.
5.Enrico Fermi, “My Observations During the Explosion at Trinity on July 16, 1945,” Fermat’s Library, http://www.atomicarchive.com/Docs/Trinity/Fermi.shtml.
6.As astronomer Jason Wright puts it, “Astronomers stare at the sky professionally with some of the most sensitive equipment in the world. If UFOs were common, we would see them all the time. It strains credulity that armies of amateurs with cameras regularly see UFOs when the professionals with giant telescopes do not.” Jason Wright, “Astronomers and UFOs,” AstroWright, December 1, 2013, https://sites.psu.edu/astrowright/2013/12/01/astronomers-and-ufos/.
7.Michael Hart, “An Explanation for the Absence of Extraterrestrials on Earth,” Quarterly Journal of the Royal Astronomical Society 16 (June 1975): 128. Also see Robert H. Gray, “The Fermi Paradox Is Neither Fermi’s Nor a Paradox,” Astrobiology 15, no. 3 (March 2015): 195–99.
8.Glen David Brin, “The ‘Great Silence’: The Controversy Concerning Extraterrestrial Intelligent Life,” Quarterly Journal of the Royal Astronomical Society 24, no. 3 (1983): 283–309, and James Annis, “An Astrophysical Explanation for the ‘Great Silence,’ ” Journal of the British Interplanetary Society 52 (1999): 19–22.
9.Robin Hansen, The Great Filter—Are We Almost Past It?, September 15, 1998, http://mason.gmu.edu/~rhanson/greatfilter.html.
10.Heike Langenberg, “Slow Gulf Stream During Ice Ages?,” Nature News, December 9, 1999, http://www.nature.com/news/1999/991209/full/news991209-10.html.
11.This could happen in many ways, but the easiest to imagine is a significant population reduction—a “die-off”—that keeps the population’s capacities below the level for a technological/industrial re-emergence. Note that dramatic climate change could result in a species that once had a technological civilization living for hundreds of thousands of years on a world where large-scale agriculture has become impossible. It is very difficult to predict what the evolutionary/sociological outcome of this scenario would be.
12.Matthew F. Dowd, “Fraction of Stars with Planet
ary Systems, fp, pre-1961,” in The Drake Equation, ed. Douglas A. Vakoch and Matthew F. Dowd (New York: Cambridge University Press, 2015), 56.
13.Steven J. Dick, Plurality of Worlds: The Extraterrestrial Life Debate from Democritus to Kant (Cambridge: Cambridge University Press, 1984), 6.
14.Dick, Plurality of Worlds, 26–27.
15.Dick, Plurality of Worlds, 62.
16.There remains some dispute over what exactly Bruno was convicted for in the heresy charge. Evidence points to more arcane issues of doctrine, rather than astronomy. His views on Copernicanism and other worlds, however, contributed to his career of conflict with the Church. Dorothea Singer, Giordano Bruno: His Life and Thought (1950; repr., New York: Greenwood Press, 1968).
17.Bernard de Fontenelle, Conversations on the Plurality of Worlds (1686; repr., London: J. Cundee, 1803), 112.
18.Dowd, “Fraction of Stars,” 67, and Steven J. Dick, Life on Other Worlds: The 20th-Century Extraterrestrial Life Debate (Cambridge: Cambridge University Press, 1998).
19.Douglas A. Vakoch, ed., Astrobiology, History, and Society: Life Beyond Earth and the Impact of Discovery (Berlin: Springer, 2013), 108.
20.Percival Lowell, “Observations at the Lowell Observatory,” Nature 76 (1907): 446.
21.William Whewell, Of the Plurality of Worlds (1853; repr., Chicago: University of Chicago Press, 2001), 207.
22.Whewell, Plurality of Worlds, 204–5.
23.Alfred Russel Wallace, Man’s Place in the Universe: A Study of the Results of Scientific Research in Relation to the Unity or Plurality of Worlds (London: Chapman and Hall, 1904).
24.Dowd, “Fraction of Stars,” 67.
25.Florence Raulin Cerceau, “Number of Planets with an Environment Suitable for Life, ne, Pre-1961,” in The Drake Equation, eds. Douglas A. Vakoch and Matthew F. Dowd (New York: Cambridge University Press, 2015), 98.
26.Natural Resources Defense Council, “Global Nuclear Stockpiles, 1945–2006,” Bulletin of the Atomic Scientists 62, no. 4 (July/August 2006): 64–66, http://media.hoover.org/sites/default/files/documents/GlobalNuclearStockpiles.pdf.
27.Stephanie Pappas, “Hydrogen Bomb vs. Atomic Bomb: What’s the Difference?,” Live Science, January 6, 2016, https://www.livescience.com/53280-hydrogen-bomb-vs-atomic-bomb.html.
28.Don P. Mitchell, “The R-7 Missile,” http://mentallandscape.com/S_R7.htm.
29.Steve Garber, “Sputnik and the Dawn of the Space Age,” National Aeronautics and Space Administration, last modified October 10, 2007, https://history.nasa.gov/sputnik/.
30.Frank Drake and Dava Sobel, Is Anyone Out There? (New York: Delacorte Press, 1992), 5.
31.Drake and Sobel, Is Anyone Out There?, 27.
32.Drake and Sobel, Is Anyone Out There?, 8–12.
33.Frank Drake, “A Reminiscence of Project Ozma,” Cosmic Search 1, no. 1 (1979): 10.
34.F. Ghigo, “The Tatel Telescope,” National Radio Astronomy Observatory, http://www.gb.nrao.edu/fgdocs/tatel/tatel.html.
35.Drake, “Reminiscence.”
36.John R. Percy, “The Nearest Stars: A Guided Tour,” Astronomical Society of the Pacific, 1986, https://astrosociety.org/edu/publications/tnl/05/stars2.html.
37.Drake, “Reminiscence.”
38.“Early SETI: Project Ozma, Arecibo Message,” SETI Institute, http://www.seti.org/seti-institute/project/details/early-seti-project-ozma-arecibo-message.
39.Drake, “Reminiscence.”
40.“Early SETI: Project Ozma.”
41.Giuseppe Cocconi and Philip Morrison, “Searching for Interstellar Communications,” Nature 184, no. 4690 (September 19, 1959): 844–46.
42.Drake and Sobel, Is Anyone Out There?, 32.
43.Drake and Sobel, Is Anyone Out There?, 45–64.
44.Drake and Sobel, Is Anyone Out There?, 47.
45.Drake and Sobel, Is Anyone Out There?, 54.
46.Drake and Sobel, Is Anyone Out There?, 49.
47.Drake and Sobel, Is Anyone Out There?, 51.
48.Maggie Masetti, “How Many Stars in the Milky Way?,” Blueshift, July 22, 2015, https://asd.gsfc.nasa.gov/blueshift/index.php/2015/07/22/how-many-stars-in-the-milky-way/.
49.Fred Hoyle, The Black Cloud (London: Heinemann, 1957).
50.Drake chose to focus just on our home galaxy, the Milky Way, because the distances to other galaxies are so large. Any source-emitted electromagnetic radiation becomes more difficult to detect the farther away it is.
51.Su-Shu Huang, “The Problem of Life in the Universe and the Mode of Star Formation,” Publications of the Astronomical Society of the Pacific 71, no. 422 (October 1959): 421–24.
52.Stanley L. Miller, “A Production of Amino Acids under Possible Primitive Earth Conditions,” Science 117, no. 3046 (May 15, 1953): 528–29.
53.Drake and Sobel, Is Anyone Out There?, 61.
54.Of course, one can also ask whether a civilization that was far more advanced than ours would still use radio at all. But like the previous issue of life requiring planets, one has to begin somewhere, and its better to underestimate the likelihood of each term than go overboard.
55.Drake and Sobel, Is Anyone Out There?, 62.
56.Drake and Sobel, Is Anyone Out There?, 52.
57.Drake and Sobel, Is Anyone Out There?, 62.
58.Drake and Sobel, Is Anyone Out There?, 64.
59.Jamieson, Reason, 20.
60.“The Television Infrared Observation Satellite Program (TIROS),” NASA Science, May 22, 2016, https://science.nasa.gov/missions/tiros/.
CHAPTER 2: WHAT THE ROBOT AMBASSADORS SAY
1.Franklin O’Donnell, “The Venus Mission: How Mariner 2 Led the World to the Planets,” Jet Propulsion Laboratory website, https://www.jpl.nasa.gov/mariner2/.
2.David R. Williams, “Chronology of Lunar and Planetary Exploration,” Goddard Space Flight Center, last modified August 8, 2017, https://nssdc.gsfc.nasa.gov/planetary/chronology.html.
3.David R. Williams, “Venus Fact Sheet,” Goddard Space Flight Center, last modified December 23, 2016, https://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html.
4.O’Donnell, “The Venus Mission.”
5.Larry Klaes, “Remembering the Early Robotic Explorers,” Centauri Dreams: Imagining and Planning Interstellar Exploration, August 29, 2012, https://www.centauri-dreams.org/?p=24285.
6.O’Donnell, “The Venus Mission.”
7.O’Donnell, “The Venus Mission.”
8.Williams, “Venus Fact Sheet.”
9.William Sheehan and John Edward Westfall, The Transits of Venus (Amherst, NY: Prometheus Books, 2004), 213.
10.Sheehan and Westfall, Transits, 213.
11.Mikhail Ya. Marov, “Mikhail Lomonosov and the Discovery of the Atmosphere of Venus During the 1761 Transit,” in Transits of Venus: New Views of the Solar System and Galaxy, Proceedings of the 196th Colloquium of the International Astronomical Union, ed. D.W. Kurtz (Cambridge: Cambridge University Press, 2004).
12.F. W. Taylor and D. M. Hunten, “Venus: Atmosphere,” in Encyclopedia of the Solar System, 3rd ed., eds. Tilman Spohn, Doris Breuer, and Torrence V. Johnson (Amsterdam: Elsevier, 2014).
13.C. H. Mayer, T. P. McCullough, and R. M. Sloanaker, “Observations of Venus at 3.15 cm Wave Length,” Astrophysical Journal 127, no. 1 (January 1958): 1–10.
14.Paolo Ulivi with David M. Harland, Robotic Exploration of the Solar System: Part 1, The Golden Age, 1957–1982 (Berlin: Springer, 2007), xxxi.
15.Ulivi and Harland, Robotic Exploration, xxxii.
16.“Planetary Temperatures,” Australian Space Academy, http://www.spaceacademy.net.au/library/notes/plantemp.htm.
17.Keay Davidson, Carl Sagan: A Life (New York: Wiley, 1999), 39–56.
18.Ray Spangenburg and Kit Moser, Carl Sagan: A Biography (Westport, CT: Greenwood, 2004), 11–29.
19.Kenneth R. Lang, “Global Warming: Heating by the Greenhouse Effect,” NASA’s Cosmos, 2010, http://ase.tufts.edu/cosmos/view_chapter.asp?id=21&page=1.
20.Tim Sharp, “What Is the Temperatur
e on Earth?,” Space.com, September 28, 2012, https://www.space.com/17816-earth-temperature.html.
21.F. W. Taylor, Planetary Atmospheres (Oxford: Oxford University Press, 2010), 12.
22.Svante Arrhenius, “On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground,” Philosophical Magazine and Journal of Science 41, no. 251 (April 1896): 237–76.
23.Spencer Weart, “The Carbon Dioxide Greenhouse Effect,” The Discovery of Global Warming, January 2017, https://history.aip.org/climate/co2.htm.
24.Spangenburg and Moser, Carl Sagan, 36–38.
25.Davidson, Carl Sagan.
26.O’Donnell, “The Venus Mission.”
27.Tony Reichhardt, “The First Planetary Explorers,” Air and Space Magazine, December 14, 2012, http://www.airspacemag.com/daily-planet/the-first-planetary-explorers-162133105/.
28.O’Donnell, “The Venus Mission.”
29.Asif A. Siddiqi, Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958–2000 (Washington, DC: National Aeronautics and Space Administration, 2002).
30.Taylor, Planetary Atmospheres, 113–15.
31.Taylor, Planetary Atmospheres, 114–24.
32.The cold trap works by keeping water in the lower part of the atmosphere. As water vapor rises, it eventually cools and condenses, falling back to Earth. This process intensifies at the tropopause (fifteen kilometers above sea level), where air temperatures drop far below freezing. Thus, all remaining water in the atmosphere is frozen out. Michael Denton, “The Cold Trap: How It Works,” Evolution News and Science Today, May 10, 2014, https://evolutionnews.org/2014/05/the_cold_trap_h/.
33.Davidson, Carl Sagan.
34.Spangenburg and Moser, Carl Sagan, 34–65.
35.“Mars Exploration Rovers: Step-by-Step Guide to Entry, Descent, and Landing,” Jet Propulsion Laboratory, https://mars.nasa.gov/mer/mission/tl_entry1.html.
36.Steven W. Squyres, Roving Mars: Spirit, Opportunity, and the Exploration of the Red Planet (New York: Hyperion, 2005), 292–93.
37.Ulivi and Harland, Robotic Exploration, xxxiii–xxxiv.
38.Vakoch, Astrobiology, History, and Society, 108.