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On the Search for Extraterrestrial Intelligence (SETI)

  • Richard B. Bilder (a1)
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1 Stephen Hawking on the 2016 TV documentary “Steven Hawking's Favorite Places,” streamed by the British CuriosityStream video service, and see also the 2010 documentary “Into the Universe with Stephen Hawking,” at

2 See F.D. Drake, Project Ozma, 14 Physics Today 40 (1961).

3 The writings and other resources concerning the possibility of extraterrestrial intelligent life and humanity's contact with alien civilizations are very extensive. Among many useful discussions, see, for example: Michael A.G. Michaud, Contact with Alien Civilizations: Our Hopes and Fears About Contacting Extraterrestrial Intelligence (2007); Searching for Extraterrestrial Intelligence: SETI Past, Present, and Future (The Frontiers Collection) (H. Paul Schuch ed., 2011); Aliens: The World's Leading Scientists on the Search for Extraterrestrial Life (Jim Al-Khalili ed., 2016); Michaud, Michael A.G., Ten Decisions that Could Shake the World, 19 Space Pol'y 131 (2003); Steven Johnson, Greetings, E.T. (Please Don't Murder Us), N.Y. Times Mag. (June 28, 2017); Steven J. Dick, Astrobiology, Discovery, and Societal Impact (2018); Donald Goldsmith, Exoplanets: Hidden Worlds and the Quest for Extraterrestrial Life (2018); Carl Sagan, Contact (1985) (the novel and the movie made from it). This subject has also, of course, been extensively and thoughtfully explored in a substantial body of science fiction writings, movies, and television programs. For a well-regarded recent example, see Liu Cixin, The Three-Body Problem (English translation, 2014). For excellent recent discussions of many of the legal and other developments and issues discussed in this Comment, see particularly: Francis Lyall and Paul B. Larsen, Space Law: A Treatise, at ch. 17 (2d ed. 2018); and John Gertz, Post-detection SETI Protocols & METI: The Time Has Come to Regulate Them Both, 69 J. Brit. Interplanetary Soc'y 263 (2016). Wikipedia offers online and informative articles—usually periodically updated and footnoted with references to primary resources—on many SETI-related matters mentioned in this Comment. I have drawn on a number of them, particularly for my “Background” discussion and, as will be indicated in footnotes, certain other topics. See, e.g., Wikipedia, Search for Extraterrestrial Intelligence, at; Wikipedia, Potential Cultural Impact of Extraterrestrial Contact, at; Wikipedia, Active SETI, at; Wikipedia, METI (Messaging Extraterrestrial Intelligence), at; Wikipedia, Post-detection Policy, at; Wikipedia, Extraterrestrial Life, at

4 Some scientific institutions and programs involved in SETI-related research or activities include: SETI Institute; University of California, Berkeley, SETI Research Center; SETI League Inc.; METI International; International Academy of Astronautics and its Permanent Committee on SETI; Harvard University SETI program; International Institute of Space Law; International Astronomical Union; International Union of Radio; British Interplanetary Society; UK SETI Research Network; and Committee on Space Research. The leading U.S. government agency likely to be concerned with SETI-related activity is the National Aeronautics and Space Agency (NASA). The most important international organization likely to be involved in SETI-related concerns is the United Nations Office of Outer Space Affairs (UNOOSA) and its Committee on the Peaceful Uses of Outer Space (COPUOS).

5 The so-called “Drake equation,” proposed by Frank Drake in 1961, is a widely accepted tool used by the scientific community to estimate the probable number of technologically advanced and communicative extraterrestrial civilizations in our galaxy. The “equation” summarizes the factors likely to play a role in the emergence of intelligent extraterrestrial life, development of an alien civilization, and the possibility of detecting it, such as the average rate of planet formation in the galaxy, the fraction of planets that can potentially support life and on which intelligent life develops, the fraction of such planets that develop technology capable of broadcasting messages into space, and the length of time it takes such civilizations do so. The “equation” suggests that, as a matter of probability, even if the fraction of planets meeting all of these requirements is very small, the existence of billions of planets in the galaxy makes it likely that, nevertheless, there are many technologically advanced alien civilizations in our galaxy. See, e.g., Elizabeth Howell, Drake Equation: Estimating the Odds of Finding E.T., (Apr. 6, 2018), at; Wikipedia, Drake Equation, at Some scientists and others are skeptical, however. In 1950, Enrico Fermi, the Italian physicist instrumental in the development of the atomic bomb, is reported to have asked “Where is everybody?,” expressing what has become known as the “Fermi paradox”—the apparent contradiction between estimates for the existence of many alien civilizations and the fact that as yet we have had no contact or other evidence of them. See, e.g., Elizabeth Howell, Fermi Paradox: Where Are the Aliens?, (Apr. 27, 2018), at; Wikipedia, Fermi Paradox, at While the lack of such contact—the so-called “great silence”—may be explained by the nonexistence of intelligent ETs and alien civilizations, SETI proponents suggest alternative explanations. These include that: alien civilizations are sparse; have not developed communications technology we could detect; are not interested in, have an ethic of not interfering with, or fear contacting us; are too distant to contact us; or they have already destroyed themselves. See, e.g., Stephen Webb, If the Universe Is Teeming with Aliens . . . Where Is Everybody? Seventy-Five Solutions to the Fermi Paradox and the Problem of Extraterrestrial Life (Science and Fiction) (2d ed. 2015); Sarah Kaplan, Scientists Believe There's Other Life in the Universe. Why Haven't We Found It Yet?, Wash. Post (July 21, 2015), at

6 See, e.g., Amina Khan, Astronomers Find a Planet Where Life Might Thrive and Just 31 Light Years Away, L.A. Times (July 31, 2019), at; Michael Greshko, Water Found on a Potentially Life-Friendly Alien Planet, Nat'l Geographic (Sept. 11, 2019), at

7 See, e.g., Andrew J. LePage & Alan M. MacRobert, SETI Searches Today, Sky & Telescope, at 44–48 (Dec. 1998). Some important U.S. radio telescopes involved in SETI searches include the Green Bank radio telescope in West Virginia, the Allen Array at the University of California in Berkeley, California, and the Arecibo telescope in Puerto Rico.

8 See, e.g., Breakthrough Initiatives, at

9 See, e.g., Katie Hunt, China's Giant Space Telescope Starts Search for Alien Life, Space + Sci. (Sept. 21, 2016), at; Wikipedia, Five- Hundred-Meter Aperture Spherical Telescope, at; Ross Anderson, What Happens if China Makes First Contact?,” Atlantic (Dec. 2017), at

10 To date, at least twelve such messages have been sent. See, e.g., Meilan Solly, New Catalogue Describes Everything We've Sent into Space, (Nov. 20, 2019), at; Wikipedia, Active SETI, supra note 3, “Realized Projects”; Wikipedia, List of Interstellar Radio Messages, at

11 See SETI Institute, Arecibo Message, at; Wikipedia, Arecibo Message, at

12 See, e.g., Joss Fong, The 116 Photos NASA Picked to Explain Our World to Aliens, Vox (Nov. 11, 2015), at

13 See the “Strategic Plan 2015–2018” that was adopted by METI International's Board of Directors on August 19, 2015 and the version that was amended on February 3, 2016, at See also Contacting Extraterrestrials: Nanoo Nanoo, Earth Invites the Inhabitants of a Distant Planet to Chat, Economist (Nov. 18, 2017) (reporting METI's “Sonar calling GJ273b” message from Norway's Remsfjord radio antenna toward Luyten's star 12.4 light years from Earth).

14 See, e.g., Brin, David, The Search for Extra-Terrestrial Intelligence: Should We Message ET?, 67 J. Brit. Interplanetary Soc'y 8 (Jan. 2014); Marko Kovic, Contacting Aliens Is a Horrible Idea: Actively Messaging Extraterrestrial Civilizations Would Be Humankind's Final Folly, Medium (Dec. 7, 2017), at; Johnson, supra note 3. See also the July 2015 statement “Regarding Messaging to Extraterrestrial Intelligence (METI)/Active Searches for Extraterrestrial Intelligence (Active SETI)” signed by twenty-eight scientists, stating that “intentionally signaling other civilizations in the Milky Way Galaxy raises concerns for all the people of Earth about both the message and the consequences of contact. A worldwide scientific, political and humanitarian discussion must be held before any message is sent,” at

15 See, e.g., Seth Shostak, Why Stephen Hawking Is Light Years from the Truth about “Dangerous Aliens, Guardian (Sept. 27, 2016), at; Seth Shostak, Should We Keep a Low Profile in Space?, N.Y. Times (Mar. 27, 2015), at See also, e.g., METI International Special, International Space Society Development Conference (May 25, 2017), at

16 UN Treaty on Principles Governing the Activity of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies (Outer Space Treaty), 18 UST 2410, 610 USTS 205 (1967), 61 ILM 386 (1968). Article I of the Treaty provides in part: “The exploration and use of outer space, including the moon and other celestial bodies, shall be carried out for the benefit and in the interests of all countries . . . and shall be the province of all mankind.” Article XI provides: “In order to promote international cooperation in the peaceful exploration and use of outer space, States Parties to the Treaty conducting activities in outer space, including the moon and other celestial bodies, agree to inform the Secretary-General of the United Nations as well as the public and the international scientific community, to the greatest extent feasible and practicable, of the nature, conduct, locations and results of such activities. On receiving the said information, the Secretary General of the United Nations should be prepared to disseminate it immediately and effectively.” For an extensive discussion of the treaty, see, for example, Lyall & Larsen, supra note 3, at ch. 3.

17 But see Lyall & Larsen, supra note 3, at 494 (noting that: “The major body of international law relevant to most SETI enquiry is the allocation and use of the radio spectrum secured through the mechanisms of the International Telecommunication Union (the ITU).”). The authors give a detailed description of the ITU and its Radio Regulations in Chapter 8 of their book. See also the AJIL Unbound Symposium on “The New Space Race,” 113 AJIL 92–129 (2019), at

18 See generally, e.g., Lyall & Larsen, supra note 3, “SETI Protocols,” at 500–05; IAA SETI Permanent Committee, IAA SETI Permanent Committee SETI Protocols, at The IAA SETI Permanent Study Group has also developed several “scales” as tools to assist in evaluating components of SETI-related decisions: the Rio Scale to quantify the impact of any public announcement regarding the detection of ET intelligence; the San Marino Scale regarding risks of transmissions from Earth; and the proposed London Scale regarding the detection of intelligent alien life.

19 IAA SETI Permanent Committee, Declarations of Principles Concerning Activities Following the Detection of Extraterrestrial Intelligence, at; Lyall & Larsen, supra note 3, “SETI Protocols,” at 500–05.

20 See, e.g., Lyall & Larsen, supra note 3; IAA SETI Permanent Committee, Draft Declaration of Principles Concerning Sending Communications to Extraterrestrial Intelligence, at; IAA, IAA Position Paper: A Decision Process for Examining the Possibility of Sending Communications to Extraterrestrial Civilizations, A Proposal (2005), available at

21 For discussions generally noting SETI-related issues and/or calling for international attention, agreements, oversight and/or regulation of SETI-related activities, see for example: Lyall & Larsen, supra note 3, at 504–05; Gertz, supra note 3; Michaud, Michael A.G., An International Agreement Concerning the Detection of Extraterrestrial Intelligence, 26 Acta Astronautica 291 (1992); Goodman, Allen E., Diplomacy and the Search for Extraterrestrial Intelligence, 21 Acta Astronautica 137 (Feb. 1990); Ney, P., An Extraterrestrial Contact Treaty?, 38 J. Brit. Interplanetary Soc'y 521 (1986); Dominik, Martin & Zarnecki, John C., The Detection of Extra-Terrestrial Life and the Consequences for Science and Society, 369 Phil. Transactions Royal Soc'y A 409 (2011); Othman, Mazlan, Supra-Earth Affairs, 369 Phil. Transactions Royal Soc'y A 693 (2011); Lyall, Francis, SETI and the Law: What if the Search Succeeds?, 14 Space Pol'y 75 (May 1998); Reynolds, Glenn Harlan, International Space Law: Into the Twenty-First Century, 25 Vand J. Transnat'l L. 225 (1992).

22 See, e.g., Michaud, Michael A.G., If Contact Occurs, Who Speaks for Earth?, 78 For. Serv. J. 23 (Apr. 2001). In September 2010, several British newspapers (The Sunday Times, The Guardian, and The Telegraph) as well as other media, reported, incorrectly, that the United Nations planned to appoint Malaysian astrophysicist Mazlan Othman, then director of UNOOSA, as the UN's ambassador to act as the first point of contact and/or meet aliens trying to communicate with or coming to Earth. However, the reports turned out to be false. The Guardian reported that Dr. Othman said: “It sounds really cool, but I have to deny it.” See, e.g., Matthew Weaver, UN Plan for “Alien Ambassador” a Case of Science Fiction?, Guardian (Sept. 27, 2010), at; N.L. Alien Diplomacy: The UN's Secretive Alien Ambassador, Economist (Sept. 28, 2010), at

23 In her article on Supra-Earth Affairs, supra note 21, Dr. Mazlan Othman, then director of UNOOSA, noted, as summarized in the abstract to her article, that: “The United Nations briefly considered the issue of extraterrestrial intelligence at the 32nd session of the General Assembly in 1977. As a result, the Office of Outer Space Affairs was tasked to prepare a document on issues related to ‘messages to extraterrestrial civilizations,’ but this area has not been followed through in more recent times.” Id. at 693.

24 There is an extensive literature discussing the tradeoffs between formal and legally binding treaties and other international agreements and soft-law or legally nonbinding international instruments, such as UN General Assembly Declarations and Resolutions, as well as the potential influence and effects of “soft-law” instruments in the development of “harder” and legally binding customary law. See generally, e.g., Informal International Lawmaking (Joost Pauwelyn, Ramses A. Wessel & Jan Wouters eds., 2012); Shaffer, Gregory C. & Pollock, Mark, Hard and Soft Law: Alternative Complements and Antagonists in International Governance, 94 Minn. L. Rev. 706 (2010). And, as regards space law more specifically, see, for example: Lyall & Larsen, supra note 3, at ch. 2 (especially “UN Resolutions,” at 39–45, and “Soft Law,” at 45–48); Soft Law in Outer Space: The Function of Non-binding Norms in International Space Law (Irmgard Marboe ed., 2012); Wessell, BranThe Rule of Law in Outer Space: The Effect of Treaties and Non-binding Norms in International Space Law, 35 Hastings Int'l Comp. L. Rev. 289 (2012).

25 See generally Lyall & Larsen, supra note 3, at 39–45 (noting, inter alia, that “the generality of states are willing to lay out principles and rules under which the exploration and use of space should be conducted and municipal space affairs be arranged,” “the evidence so far at least is that the space-competent states do generally comply with the broad principles expressed in these resolutions,” and that “the history of compliance with the UN Space Resolutions has swiftly elevated each of them at least to the category of ‘soft law’”).

On the Search for Extraterrestrial Intelligence (SETI)

  • Richard B. Bilder (a1)


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