SETI: on the edge of astrobiology



Following up on yesterday’s post about Rep. Lamar Smith’s interest in SETI and the inclusion of $10 million for a “search for technosignatures” (SETI) in a NASA authorization bill for 2018-2019, I’m going to review a little history of SETI.

SETI advocates have been arguing of late that SETI should be funded by NASA’s astrobiology program.* I disagree.

SETI uses ground-based telescopes to listen for radio signals of extraterrestrial intelligent origin. (As noted in a PBS TV program“NOVA Wonders Are We Alone?”, which aired last week, “we’ve been listening for almost 60 years, and, so far, crickets.”) It’s the National Science Foundation that funds ground-based telescopes (and historically, many ground-based telescopes have been, and continue to be, public-private partnerships.)

Following historical guidance from the National Academy of Sciences, SETI falls within the domain of astronomy and astrophysics – not astrobiology. Some of the Academies’ decadal surveys of astronomy and astrophysics have noted the promise of searching for evidence of extraterrestrial intelligence by using radio telescopes to listen for signals of technological origin. (See below.)

However, no decadal survey has recommended SETI as a research priority for NASA, the National Science Foundation, or any other federal agency, nor has the Academies’ Space Studies Board (SSB) or the SSB’s Committee on Astrobiology and Planetary Science (CAPS) (or CAPS’ predecessor the Committee on the Origins and Evolution of Life). While some scientists in astronomy/astrophysics and the astrobiology community see value in searching for evidence of extraterrestrial intelligent life, most see SETI as a highly speculative, long-term endeavor. Less speculative, shorter-term space research projects take precedence for federal funding.

In its “SETI 2020” research roadmap, published by the SETI Institute in 2002, the SETI community itself noted, “The annual appropriations of funds in a political arena are, in hindsight, a poor venue for support for an open-ended quest. We need to fall back on historical precedent, and primarily rely on philanthropy to fund the search.”  (Clearly the Institute has changed its strategy since then, presumably because, Breakthrough Listen aside, sufficient private-sector funding is not forthcoming.)

In my humble opinion, SETI is an endeavor that falls outside the purview of government funding and is suited to private-sector support.

NASA did fund a SETI program from 1972 to 1993 (more on how this happened in a subsequent post). Congress cancelled the program in 1993. Neither the astronomy and astrophysics community nor the exobiology/astrobiology community has embraced SETI as a priority for government funding since then.

The astrobiology community is in agreement that searching for evidence of habitability and life in our own solar system and studying the potential habitability of planets around other stars should remain top priorities in space research. It does not assign high priority to SETI. The 2015 astrobiology science strategy, a product of input from hundreds of members of the astrobiology community and published by NASA, has this to say about SETI:

“There is the question of technological civilizations elsewhere. Complex life may evolve into cognitive systems that can employ technology in ways that may be observable. Nobody knows the probability, but we know that it is not zero. As we consider the environments and biospheres of other planets, this is among the type of developments we could anticipate. While traditional Search for Extraterrestrial Intelligence (SETI) is not part of astrobiology, and is currently well-funded by private sources, it is reasonable for astrobiology to maintain strong ties to the SETI community.

There are also other ways not included in contemporary SETI that astrobiology can contribute to the search for technological life. Chief among these is the search for “technosignatures.” As we explore the exoplanets and search for biosignatures, we should also be aware of the possibility that technological life could also perturb atmospheric composition, or other planetary qualities, in observable ways. Rather than argue for or against the likelihood of finding such a signature, or attempt to describe specifically what such a signature would look like, we should be sure to include it as a possible kind of interpretation we should consider as we begin to get data on the exoplanets.”

But let’s go back to guidance from the National Academies. From its beginning, NASA has sought, and largely heeded, advice from the Academies on priorities in space science (within the limits of its budget…). The National Academy of Sciences has conducted decadal surveys of astronomy and astrophysics since the 1970s. It produced its first decadal survey of priorities in planetary science in 2003 and its second in 2012. (The latter survey is now in midterm review.)

Over the past 50 years, the SSB has produced numerous reports and recommendations relating to exobiology and astrobiology. While the search for evidence of extraterrestrial life has remained a top research priority in SSB reports, SETI has not.

In an August 11, 1964, memorandum to NASA associateadministrator for space science and applications HomerNewell on ‘‘future goals of the space science program,’’ the Academies’ Space Science Board (predecessor of the Space Studies Board) recommended that NASA adopt as its most importantspace science goal for 1971–1986 ‘‘the exploration of planetswith particular emphasis on Mars leading toward eventualmanned exploration. This objective includes the search forextraterrestrial life.’’

In a 1971 report, Priorities for Space Research 1971-1980, the SSB stated:

“Exobiology…involves not only the search for evidence of past or present extraterrestrial life but also for indications of nonbiological chemical evolution that could support or clarify our present ideas about the origin of life and the possibility that terrestrial life might survive on other planets. This field has almost universally caught the imagination of scientists and the public at large… The study of exobiology – particularly if life is found elsewhere in the universe – will have a profound impact.”

The Academies’ decadal survey of astronomy and astrophysics for the 1970s, conducted for NASA and the National Science Foundation and published in 1972, addressed the promise of searching for radio signals of extraterrestrial intelligent origin:

“Our civilization is within reach of one of the greatest steps in its evolution: knowledge of the existence, nature, and activities of independentcivilizations in space…. An assurance of rapid results cannot be made in a search for extraterrestrial civilizations. Such a search is akin to the one for the proverbial needle, but in this case the haystack contains three dimensions of space and two more of time and frequency, and there may be no needle. It is only our knowledge of the value of that needle, if it exists, that compels us to pursue such a difficult objective…. Despite the power and promise of our instruments for serious searches for other civilizations, no major search has taken place. The explanation lies in the intense pressure on major astronomical instruments to produce the astrophysical results that are the mainstream of astronomical research. Because we cannot accurately predict the effort needed to detect another civilization, quick results cannot be guaranteed. Indeed, the time estimated for a single radio telescope to yield a reasonable probability of success is a few decades, even with high-speed equipment and procedures. In today’s rush such a time scale is usually considered unacceptable. Nevertheless, each passing year has seen our estimates of the probability of life in space increase, along with our capabilities for detecting it.”

This survey committee did not recommend the undertaking of a SETI search. Its top priorities for the ‘70s were the construction of astronomy facilities, with top priority assigned to the Very Large Array.

The Academies’ decadal survey of astronomy and astrophysics for the 1980s was conducted, again, for NASA and NSF, and published in 1982. The committee assembled to conduct this survey set up seven working groups, including one on SETI. This survey committee recommended four major new programs and seven “moderate” new programs. Among the “moderate” programs was SETI:

“The recommended moderate new programs address a variety ofopportunities in astronomy…. While the Committee recognizedthat [SETI] has a character different from that normally associated withastronomical research, intelligent organisms are as much a part of the Universe asstars and galaxies; investigating whether some of the electromagnetic radiationnow arriving at Earth was generated by intelligent beings in space may thus beconsidered a legitimate part of astronomy. Moreover, the techniques that can nowbe most effectively brought to bear on a SETI program for the 1980’s are those ofastronomy…. Since the chance for a successful detection in the next decade is quite uncertain and may be small, it should be understood that the SETI effort is to be undertaken on a long-term, evolutionary basis…. Modest support of such programs by U.S. funding agencies is a legitimate scientific activity, and choice of programs within each agency should be made through the normal process of peer review.”

The Academies’ decadal survey of astronomy and astrophysics for the ‘90s presented a different perspective on SETI. In considering the scientific potential of searching for evidence of life in our solar system and searching for planets around other stars, the SSB’s Task Group on Astronomy and Astrophysics for the 1990s noted in its report:

“[SETI] has a different character than the broader-based search for life and is not addressed in this study. Obviously, if the NASA Search for Extraterrestrial Intelligence (SETI) program were to find radio signals from another planetary system, it would be a tremendously exciting and significant event. In the case of the more restricted study described here, even the hint of life in another planetary system would trigger a new era in planetary research.”

Although the Academies had not endorsed SETI as a top priority in space research, NASA did initiate a 10-year SETI research and development program in the 1980s,to culminate in a ground-based search for signals. NASA started its SETI listening project in 1992. Congress cancelled it in 1993.

The SSB’s first decadal survey of priorities in solar system exploration, commissioned by NASA in 2001 and published in 2003, identified four ‘‘cross-cutting themes that integrate the various goals identified by the panels,” including key themes in astrobiology: the first billion years of solar system history; volatiles and organics; the stuff of life; and the origin and evolution of habitable worlds. The next SSB decadal survey of priorities in solar system exploration, commissioned by NASA and published in 2012, highlighted the growing role of astrobiology in planetary exploration. Neither of these surveys addressed SETI.

In the NASA Authorization Act of 2000, Congress called for a National Academies review of NASA and other government and nongovernment programs focused on the search for life in the universe. In a 2003 report on this review, the SSB’s Committee on the Origins and Evolution of Life (COEL) noted:

“Perhaps the most romantic venture in astrobiology is the search for extraterrestrial intelligence (SETI). This effort has had a checkered reception by scientists and federal lawmakers, with the result that the current efforts are almost entirely privately funded. The SETI Institute…the nexus of such efforts in the United States, has accomplished in a spectacular way the founding of a science institute and the procurement of stable private funding to carry on the search.”

I should like to note that in 2005, NASA awarded a grant to a SETI researcher for a project called “detection of complex, electronic markers of technology.” In 2008, NASA amended its solicitation for space science research proposals to include “detection and characterization of other planetary systems including those that may harbor intelligent life” within the scope of its Origins of Solar Systems research program.

The bottom line is that traditional SETI – using ground-based radio telescopes to listen for signals of extraterrestrial intelligent origin – falls outside the boundaries of NASA’s astrobiology program.

All National Academies reports cited in this post are available free online at

* I am a consultant to NASA’s astrobiology program. No one asked me to write this post.

3 Responses to “SETI: on the edge of astrobiology”

  1. John Rummel Says:

    Linda, you say “Although the Academies had not endorsed SETI as a top priority in space research, NASA did initiate a 10-year SETI research and development program in the 1980s, to culminate in a ground-based search for signals.” This is not true, as written. For example, the Bahcall Decadal Study (Decade of Discovery…”) stated:

    “Ours is the first generation that can realistically hope to detect signals from another civilization in the galaxy. The search for extraterrestrial intelligence (SETI), involves, in part, astronomical techniques and is endorsed by the committee as a significant scientific enterprise. Indeed, the discovery in the last decade of planetary disks, and the continuing discovery of highly complex organic molecules in the interstellar medium, lend even greater scientific support to this enterprise. Discovery of intelligent life beyond the earth would have profound effects for all humanity. NASA’s decade-long Microwave Observing Program is based on a particular set of assumptions and techniques for exploring the SETI problem. This committee, like the Field Committee before it, believes strongly that the speculative nature of the subject also demands continued development of innovative technology and algorithms. A strong peer-reviewed, university-based program should be an integral part of this effort.”

    That agreed with what the Astronomy and Astrophysics Decadal Survey (chaired by George Field) had earlier said in recommending SETI as a “new start” endeavor, specifically “An astronomical Search for Extraterrestrial Intelligence (SETI), supported at a modest level, undertaken as a long-term effort rather than as a short-term project, and open to the participation of the general scientific community.”

    That Decadal stated, as well:
    “After reviewing the arguments for and against SETI, the Committee has concluded that the time is ripe for initiating a modest program that might include a survey in the microwave region of the electromagnetic spectrum while maintaining an openness to support of other innovative studies as they are proposed. Since the chance for a successful detection in the next decade is quite uncertain and may be small, it should be understood that the SETI effort is to be undertaken on a long-term, evolutionary basis.”

    In short, it is mistaken to suggest that the NAS Decadal Studies did not support SETI as a research activity — and it should be noted that the NAS endorsement came before the Microwave Observing Project was initiated (as a project), and that a parallel university grants program continued from before the point where I joined NASA until after I left (the first time). In that case, it was lobbying by Lou Friedman that stirred up the Congressional opposition to the grants program, and Wes Huntress shut that down in 1994 — for politics, not for content.


    • doctorlinda Says:

      Thanks for your comments, John. I interpret this endorsement slightly differently than you do. And as I showed in my May 15 blog post, over the years the National Academies reports have toned down their words of endorsement for SETI. The Academies have never tagged SETI as a top, or urgent, priority. The draft House Appropriations Committee report on NASA’s budget request recommends $10 million in the astrophysics – not the astrobiology – program budget for a search for technosignatures (a.k.a. SETI). We’ll see if that recommendation survives in the final appropriations bill – if we ever get one for fiscal year 2019. (For my readers, I’ll note that John Rummel, a long-time colleague and friend of mine, currently works for the SETI Institute.)

  2. John Rummel Says:

    N.B., I am an employee of the SETI Institute and chair their Science Advisory Board. I also have run NASA’s exobiology and astrobiology programs on and off over 3 decades. Most results have been good!

    Laying aside Space Studies Board or Astrophysics decadal studies, it is useful to consider just the words in the recent (2015) NASA-published Astrobiology Strategy. This may sound familiar to anyone who reads the Congressional Appropriations language:

    “Therefore, over the coming decades as we develop the ability to discern the nature of exoplanets and examine them for anomalous properties which might be biosignatures, we should also be aware of the possibility of planets with anomalies that are the result of technological activities. Much attention has focused on which qualities of terrestrial life might be universal, and therefore relevant to the search for biosignatures; similarly, it is worth considering which aspects of technological civilization might be universal, how such qualities should be expected to affect the observable aspects of a planet, and how they might be discernible from other biosignatures.” (p. 76)

    Thus, in that (somewhat hastily prepared) document, NASA itself has included SETI-like activities as part of astrobiology, steering carefully clear elsewhere of anything with “microwave” in it, based on the record of a comprehensive project to accomplish SETI objectives (the SETI Microwave Observing Project) that was terminated for political reasons alone. No technological milestones were ever failed by that project, nor any of the scientific rationale ever disproved. Note that the existence of planets around other stars was still speculative at the time, and I believe that we have some good evidence that that scientific assumption has been validated….

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