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Advancing the Search for Technosignatures

What a pleasure to see — after three decades — a grant from NASA for a SETI project, and on technosignatures at that. NASA’s history with SETI has been a challenging one given the subject’s reception in Congress. It was in 1971 that the agency funded Barney Oliver’s study on the huge array called Project Cyclops, whose price-tag would have been astronomical, but the report in which it was described provided numerous insights into the SETI effort. NASA’s engagement with SETI later came under fire from William Proxmire in the Senate, resulting in the termination of SETI funding in 1982. Proxmire would later change his mind on SETI’s value.

Even so, the NASA Microwave Observing Program (MOP) planned as a search of 800 nearby stars in the early 1990’s was again targeted in Congress and canceled shortly thereafter. The SETI effort developed in the ensuing years without government funding through efforts like Project Phoenix, which picked up the Mobile Observing Program under the guidance of Jill Tarter and the SETI Institute. With a number of interesting projects along the way, SETI has remained an ad hoc, privately funded effort in the US, with ongoing work through Breakthrough Listen, the Allen Telescope Array, the Berkeley SETI Research Center (SERENDIP) and others. The SETI League continues an energetic grassroots effort under the guidance of Paul Shuch. It’s interesting to note that in China, SETI is explicitly folded into the FAST radio observatory’s charter.

I haven’t gotten into optical SETI or other SETI projects in the US and abroad, but the point is that a new NASA grant makes a welcome return of NASA’s willingness to look at SETI, and with an eye toward the cutting-edge question of technosignatures as opposed to the reception of radio or optical signals. Here we’re talking about what might be created by advanced cultures, everything from vast Dyson spheres exploiting the host star’s energies to industrial pollution in exoplanet atmospheres, or even city lights. Exoplanet research motivates the current attention, says Adam Frank (University of Rochester), the primary recipient of the grant. Says Frank:

“The Search for Extraterrestrial Intelligence (SETI) has always faced the challenge of figuring out where to look. Which stars do you point your telescope at and look for signals? Now we know where to look. We have thousands of exoplanets including planets in the habitable zone where life can form. The game has changed.”

Image: Artist’s impression of the exoplanet LHS 1140b, which orbits its star within the “habitable zone” where liquid water might exist on the surface. The LHS 1140 system is only about 40 light-years from Earth, making it a possible target for studying the atmosphere of the planet if it has one. Credit: M. Weiss/CfA.

Called “Characterizing Atmospheric Technosignatures,” the new study will focus on solar panels and pollutants as indicators of technological activities. Avi Loeb (Harvard University) explains:

“The nearest star to Earth, Proxima Centauri, hosts a habitable planet, Proxima b. The planet is thought to be tidally locked with permanent day and night sides. If a civilization wants to illuminate or warm up the night side, they would place photovoltaic cells on the day side and transfer the electric power gained to the night side.”

What the study probes is how something like this would be detected if present, as a way of developing the mathematical and observational tools that can extend technosignature searches to various nearby stars. We are developing the ground- and space-based observatories with which this work can be conducted, but telescope time is precious, and knowing how and where to look is a critical issue. As we begin to be able to probe the atmospheres of rocky planets, we’ll have the potential for detecting not just biosignatures but evidence of artificially produced molecules that, like chlorofluorocarbons (CFCs), are unlikely to appear naturally.

Along with Harvard’s Loeb, Frank is joined in the effort by Penn State’s Jason Wright, Mansavi Lingam of the Florida Institute of Technology, and Jacob Haqq-Misra of Blue Marble Space. Out of the study, we can hope, will come quantitative information about how the project of technosignature detection can proceed. Let me recommend Frank’s The Light of the Stars (W. W. Norton & Company, 2018), along with Jason Wright’s Astrowright site for continuing insights into technosignatures. Also have a look at Wright’s Glimpsing Heat from Alien Technologies, published in these pages several years ago.


Comments on this entry are closed.

  • Thomas W. Hair June 23, 2020, 12:02

    The idea that an ancient intelligence would use solar panels for energy production is absurd. Our civilization is less than ten thousand years old and we are already on the verge of harnessing fusion power. Why in the world would they bother to dig up precious raw materials and assemble them to capture fusion power from a star when they can make as many little stars as they want.

    This endeavor is simply inside the box thinking writ large with a big NASA check…hope I’m wrong and we find them, but we need to drop our shared cultural baggage if we want to discover a five billion year old intelligence.

    • Alex Tolley June 23, 2020, 17:15

      I agree.

      But consider for a moment the case of ETI in Clarke’s Odyssey quadrilogy. Only 4 humans in any way communicate with ETI or their surrogates. Dave Bowman, Heywood Floyd, Chris Floyd, Frank Poole. If ETI was a god, and Bowman or Halman “angels”, then in a millennium, only 4 “priests” have been able to communicate with the invisible ETI. Quasi-religious, no?

      The monolith on the Moon (and the others discovered) are the only physical if enigmatic, objects indicating ETI’s presence. The ETIs, and Bowman after his transformation into the Starchild, are no longer physical, although they can influence physical things.

      If there were such ETI monitoring us nearby, how would we be able to detect them? Would it require prodding a reaction from them that could not be explained by a natural phenomenon? To wade into tinfoil hat territory, have we seen such phenomena? In Asimov’s “The End of Eternity”, the Eternals change history by making tiny, but critical, changes to events. How could such deliberate manipulations be detected (not even all our primitive covert operations are detected)?

      So I agree that we need to break out of our limited “in the box” thinking, but how do we detect the [near] undetectable? I suspect the obvious answer by the SETI folks is that all we can do is look for things that we can detect and hope we get lucky.

      • Thomas W. Hair June 25, 2020, 14:13

        Alex, once again you are spot on. Now “Open the pod bay doors please HAL”.

        PS If you have Alexa, try that phrase. You’ll love the answer. Makes my wife call me “nerd” every time.

  • Alex Tolley June 23, 2020, 15:55

    I am glad that this small step in public funding of SETI is happening. What I am not sure about are the ideas. For example, CFCs have been phased out due to ozone damage. Human manufacture will have lasted for less than a century (except for the illegal manufacture that appears to be happening in Asia). As a civilization, we are changing to renewable energy. We have been trying to cut down on other pollution from agriculture and industry too. If we succeed, then there will be no techno-signatures for ETI to look for on earth, and we wouldn’t find them elsewhere for the same reasons. Solar panels or other large physical structures to capture solar energy are also likely to be a transient technology to be replaced by something far better. Given that ETI is almost certainly very far away from us in technological development – very primitive or extremely advanced, it seems like a mistake to look for technology signatures that we have developed with the last few hundred years. City lights make more sense to me, although there has been some effort to reduce light pollution now that we are understanding the need for the darkness that organisms have and the harm its absence generates. “Waste” heat seems more universal and worthy of looking for. It also does not require assumptions of ETI biology (do they use visible light to see) or even biology at all (robot civilizations).

    I hope that we don’t focus too much on target planets. ETI may well have expanded off-planet to fill its system. If so, how they have done this we don’t know (colonizing worlds, converting asteroids, space habitats). While Dyson swarms are one possible techno-signature, again, this may just be our blinkered idea of a likely technology, based on our system of requiring an expanding economy, and with it energy.

    SciFi is full of stories about really advanced species. I also like Clarke’s 3rd Law:

    Any sufficiently advanced technology is indistinguishable from magic

    How do we search for what looks like “magic”?

    • NS June 23, 2020, 18:29

      Admittedly knowing next to nothing about the whole subject, my initial reaction was the same as yours and Thomas W. Hair’s above. Solar panels and pollutants seem way too parochial. The idea of looking for some kind of generic tech signature like infrared excess strikes me as a much better approach.

    • charlie June 23, 2020, 19:14

      “Waste” heat seems more universal and worthy of looking for.

      “Waste heat ” Has always come across to me as a Trojan horse which has the express purpose of trying to force government people to accept the so called “green revolution” that we are now been inundated in the news media with as a justification to adapt 2 extremely unnecessary and highly expensive technologies . I would not go this route as their clearly exist within the context of nuclear Fusion a far greater benefit to humanity overall with very very little downside; so I would give up this idea that the waste heat idea is somehow valid.

      • Ron S. June 23, 2020, 21:17

        “…nuclear Fusion a far greater benefit to humanity overall with very very little downside;”

        It is unwise to make conclusions about a technology that does not exist. We pursue it in the hope of benefits but the cons are only dimly understood until the technology (and there may be many viable fusion technologies) exists.

      • Alex Tolley June 23, 2020, 21:21

        I think you might want to [re]read the Wright CD post: “Glimpsing Heat from Alien Technologies” to understand what “waste heat” means in this context. Fusion power is not going to obsolete it.

      • Harold Shaw June 23, 2020, 22:12

        The term “waste heat” as Alex is using it refers to the heat created by anything that produces electrons (including fusion reactors) or uses electrons. The heat from your laptop or television is “waste heat”. “Waste heat” is real and unavoidable.

        Unlike global warming which is real and avoidable. This is a science blog. We may believe aliens are possible but probable, but we don’t ignore science. Heck, many of us want to use the science of global warming to terraform Mars!

        • Gary Wilson June 24, 2020, 14:16

          There should be no need to “force government people to accept the so called “green revolution” that we are now been inundated in the news media with as a justification to adapt 2 extremely unnecessary and highly expensive technologies”. If you believe in the scientific method and its application to draw conclusions based on the data available you will see that a transformation of the global production of energy away from the use of fossil fuels is essential to our survival. We don’t have fusion energy but we do have solar panels, wind generators, and other forms of “green” energy. These will continue to be improved upon. The use of fossil fuels is a true existential threat to humanity. Read the science and you will see the truth of it. Read some of Jim Hansen’s papers. It is excellent and full of accurately presented data from several decades of his brilliant work.

          • Harold Shaw June 24, 2020, 18:43

            Was this intended for me? I hope I didn’t make the impression that I doubt the reality of and threat posed by global warming.

            • Gary Wilson June 27, 2020, 18:54

              No it definitely wasn’t intended for you Harold. Sorry I have placed the comment in the wrong spot. My quote came from another contributor.

      • enrique cordova rodriguez June 24, 2020, 21:55

        Sorry, Charlie

        ‘Waste heat’ is an unavoidable consequence of the Laws of Thermodynamics,

        you know,
        1) You can’t win
        2) You can’t break even,
        3) You can’t even get out of the game.

        When energy is transformed from one form to another, some is always left over. It goes out the radiator, or the tailpipe, as waste heat.

        It is not a liberal MSM conspiracy designed to shove a sinister socialist plot down our throat.

        And BTW, don’t forget the zeroeth Law

        0) Its the only game in town.

  • Robin Datta June 24, 2020, 1:27

    “’It’s tough to make predictions, especially about the future’”
    – often attributed to Yogi Berra
    And it becomes a whole lot more difficult when there is nary an inkling about the past of intelligent aliens.

    Deforestation and desertification and new social restructuring with agriculture were theretofore unknown. Likewise, all the features since the industrial revolution. And whether we count ten millennia or three centuries, they are both brief in astrobiological perspectives.

    A target for the SETI in space is also a target in times – their time and our time; it would be quite fortuitous for the times to be anywhere close to alignment. The future is speculative to us, from genetic engineering to cyborgs to AI, megastructures and even machine civilizations. Those phases of the future could be ancient history to others.

    Parsimony rather than profligacy may shape activities to minimal disruptions of matter & energy such that they are almost undetectable. And what was habitable yesterday may not be so today, and may have been abandoned for more clement climes. And sites of activity today may not be the home planet or even the home star of an alien intelligence.

  • Alex Tolley June 24, 2020, 9:07

    The future is speculative to us, from genetic engineering to cyborgs to AI, megastructures, and even machine civilizations. Those phases of the future could be ancient history to others.

    Agreed. It should also be noted that much of what we have achieved has required rapid economic growth. This is not sustainable. As has been pointed out before, at our current (but slowing) rate of growth, just a few millennia will pass before we require the full energy output of our sun, and the same again of our galaxy (actually outpacing light speed to attain it). 10 millennia is a cosmic eyeblink which suggests to me that economic growth, and possibly much industrial development and even technology growth must plateau or return to the very low growth rates of pre-industrial societies, coupled with periodic collapses and resets. Human civilization might just exhaust itself or, as some techno-optimists believe, become transcendent and have no need for an economy to sustain it. While we have no idea of what the future brings, what is clear is that human civilization has burst onto the cosmic scene in an instant, flower, and possibly die before there is another potential ETI to communicate with.

  • Alex Tolley June 24, 2020, 9:27

    Parsimony rather than profligacy may shape activities to minimal disruptions of matter & energy such that they are almost undetectable.

    Do you have a vision of how we can get to such a parsimonious state as a civilization? What might the consequences be?

    • Robin Datta June 26, 2020, 10:52

      “Growth for growth’s sake is the ideology of the cancer cell”.

      The biological imperative for physical growth and the concomitant consumption of resources (=matter+energy) could perhaps be channelled towards accumulating, analysing, integrating and extrapolating from vast databases, by artificial intelligence. The physical basis for this might be Matrioshka brains. The basis might also be some quantum engineering technologies beyond present conception, which first present as quite incomprehensible, just as Alpha Go’s moves could not be understood by the reigning Go champion: such technologies might be nearly undetectable.

      Perhaps all human mental functions could be simulated by that same intelligence, within which might exist populations of mentally interconnected superintelligent virtual humans… merging, splitting, dissolving and appearing according to need, similar to the higher levels of existence in the Indic traditions.

  • E.P. Grondine June 24, 2020, 11:03

    In the 1950’s, researchers thought that radar systems would be a good place to look. I am wondering if planetary defense detectors, in either the optical or radar ranges, might provide large enough signals to be detected.

    • Paul Gilster June 24, 2020, 16:29

      Arecibo would doubtless be detectable, though likely as a non-repetitive transient in the alien sky.

  • Geoffrey Hillend June 24, 2020, 17:41

    Quote by Thomas W. Hair: “Why in the world would they bother to dig up precious raw materials and assemble them to capture fusion power from a star when they can make as many little stars as they want.” Solar panels are made of glass, plastic and aluminum which are very abundant and not precious. source: Google. There a hundreds of thousands of homes in the S.F. bay area in California. Every home has a plastic blue recycling can which is picked up by the garbage companies every week which is the same in the cities in the entire United States. Since I recycle glass, plastic and aluminum every day, maybe if we never recycled them, then the sand on the beaches which is what glass is made from, they might become precious after a long time. Aluminum is the most abundant metal by mass. It is the third most abundant of all the elements (after oxygen and silicon). Glass is made from silica.

    I agree with you about electric power from fusion reactors. The problem is that all of the fusion reactors under construction and working are not efficient enough to use as a power plant to supply enough power for our homes etc like fission reactors. Also they don’t keep fusion going very long. The fully operational ITER is scheduled to open in 2025 and it won’t reach maximum output until 2035 with a maximum of only twenty minutes of fusion burning. Wikipedia https://en.wikipedia.org/wiki/ITER

    Fusion reactors which can supply our electric power needs are far off in the future. I would say the first one might be ready in fifty to one hundred years which is optimistic considering that scientists and physicists don’t even have a working design of an efficient long burning fusion electric power plant. I certainly would be nice to have those designs today.

  • Michael Fidler June 25, 2020, 11:27

    A little speculation on my part, the next stage in our future is to become an advanced civilization of Kardashev scale Type 2. This involves using all of the energy output of the sun. So how could we go about doing just that?
    The possibility of using the energy from solar flares would seem to be the most practical method. We have a very good comprehension of the magnetic/electric activity in physics and magnetic reconnection is the huge powerhouse of solar flares. This could become a method to power interstellar travel both from flares themselves to recreating it to power the ships for relativistic speeds.

    What we should be looking for is in the form of intermittent signals around stars from UV/ X Rays being released, that does not indicate a natural chaotic flare event.

    This may hold true for M dwarfs that are flaring and also the ones that are not flaring in the sense of being able to control the flares. So how about looking years into our future and see how we could ride the powerful solar flares to near light speed? This is a technosignature that may be observable from our nearest neighbor “Proxima Centauri”!

  • Wojciech J June 25, 2020, 14:42

    Redirecting efforts towards Dysonian SETI has some other implications for our understanding of the universe that might be not apparent on first look.It is rather implausible that a civilisation capable of creating megastructures or at least technological manipulation of its own planet would be unaware of planets with biospheres in the same galaxy.Even our civilisation is close to building space telescopes allowing such discoveries to be made. Hence if we would detect any technosignatures in our galactic neighbourhood we would also know that they are simply not interested, at least directly, in any contact.
    It will be an interesting project, but I think the search for exoplanets with signs of recognisable biosphere will give us more parameters to work with. We are still quite blind in regards to our knowledge of the universe, even our own Solar System remains largely unknown to us.

    • ljk June 26, 2020, 10:12

      Technosignatures are finally being searched for because those who now run the main SETI efforts are no longer completely in the grasp of the Radio SETI gang that dominated SETI for decades and kept the Optical efforts down from their first modern call for such methods in 1961 until circa 1998.

      Are there actual Dyson Shells or other megastructures out there? We don’t know. However, if we don’t look we will likely never know because except for Tabby’s Star, most professional astronomers are still not deliberately searching for such objects. Maybe in another fifty years….

      Are such advanced beings ignoring us? It is not impossible, especially if there are a lot of our kind (relatively primitive organic species that have just emerged in a cosmic sense and are barely expanding into the galaxy) and fewer of the kind that build Dyson Shells and such.

      What would such beings have to say to us? I am quite skeptical of the notion by Sagan et al that they would be giving away their extensive knowledge and technology to uplift a bunch of cosmic newbies, especially to the kind that have shown what they often do with new technology to each other.

      They may also simply not know we are there: 400 billion star systems with roughly 10 planets apiece on average is a lot of places to know about. And we have only been announcing our presence electromagnetically since the mid-Nineteenth Century.

      Yes, they may know that Earth is covered in organics, but again, that does not automatically mean tool-building intelligence and if there are a lot of planets with organic life as even Rare Earthers attest to, they may not be inclined to chase every biosignature.

      I know it can be hard to imagine after millennia of believing that humanity are the Special Chosen Ones of the Cosmos, but we are, as Sagan once said, one cosmic voice in the fugue.

  • Glenn Devlin October 22, 2020, 12:46

    I’m wondering if the Mars Observer or any of our probes on Mars have taken a picture of the earth in a manner that we can see the light from our own techno-signatures and use it as a comparative baseline for scanning other planets for similar signatures?

  • ljk October 26, 2020, 15:05


    [Submitted on 14 Sep 2020]

    Novel Technosignatures

    A. A. Jackson, Gregory Benford

    Technosignatures can represent a sign of technology that may infer the existence of intelligent life elsewhere in the universe. This had usually meant searches for extraterrestrial intelligence using narrow-band radio signals or pulsed lasers.

    Back in 1960 Freeman Dyson put forward the idea that advanced civilizations may construct large structures in order to capture, for use, the energy of their local star, leading to an object with an unusual infrared signature.

    Later it was noted that other objects may represent the signature of very advanced instrumentalities, such as interstellar vehicles, beaming stations for propulsion, unusual beacons not using radio or laser radiation but emission of gamma rays, neutrinos or gravitational radiation.

    Signs may be unintentional or may be directed. Among directed and undirected signs we present some models for signaling and by-product radiation that might be produced by extremely advanced societies not usually considered in the search for extraterrestrial intelligence.

    Comments: 12 pages, 16 figures

    Subjects: Popular Physics (physics.pop-ph)

    Cite as: arXiv:2009.08873 [physics.pop-ph]
    (or arXiv:2009.08873v1 [physics.pop-ph] for this version)

    Submission history

    From: Albert Jackson [view email]

    [v1] Mon, 14 Sep 2020 16:08:53 UTC (1,103 KB)