Astronomer: use lasers as Earth’s “porch light” to attract aliens

Via MIT News and the “Astronomers with frickin’ laser beams on their heads” department comes this odd idea.

If extraterrestrial intelligence exists somewhere in our galaxy, a new MIT study proposes that laser technology on Earth could, in principle, be fashioned into something of a planetary porch light — a beacon strong enough to attract attention from as far as 20,000 light years away.

An MIT study proposes that laser technology on Earth could emit a beacon strong enough to attract attention from as far as 20,000 light years away. Image: MIT News

The research, which author James Clark calls a “feasibility study,” appears today in The Astrophysical Journal. The findings suggest that if a high-powered 1- to 2-megawatt laser were focused through a massive 30- to 45-meter telescope and aimed out into space, the combination would produce a beam of infrared radiation strong enough to stand out from the sun’s energy.

Such a signal could be detectable by alien astronomers performing a cursory survey of our section of the Milky Way — especially if those astronomers live in nearby systems, such as around Proxima Centauri, the nearest star to Earth, or TRAPPIST-1, a star about 40 light-years away that hosts seven exoplanets, three of which are potentially habitable. If the signal is spotted from either of these nearby systems, the study finds, the same megawatt laser could be used to send a brief message in the form of pulses similar to Morse code.

“If we were to successfully close a handshake and start to communicate, we could flash a message, at a data rate of about a few hundred bits per second, which would get there in just a few years,” says Clark, a graduate student in MIT’s Department of Aeronautics and Astronautics and author of the study.

The notion of such an alien-attracting beacon may seem far-fetched, but Clark says the feat can be realized with a combination of technologies that exist now and that could be developed in the near term.

“This would be a challenging project but not an impossible one,” Clark says. “The kinds of lasers and telescopes that are being built today can produce a detectable signal, so that an astronomer could take one look at our star and immediately see something unusual about its spectrum. I don’t know if intelligent creatures around the sun would be their first guess, but it would certainly attract further attention.”

Standing up to the sun

Clark started looking into the possibility of a planetary beacon as part of a final project for 16.343 (Spacecraft, and Aircraft Sensors and Instrumentation), a course taught by Clark’s advisor, Associate Professor Kerri Cahoy.

“I wanted to see if I could take the kinds of telescopes and lasers that we’re building today, and make a detectable beacon out of them,” Clark says.

He started with a simple conceptual design involving a large infrared laser and a telescope through which to further focus the laser’s intensity. His aim was to produce an infrared signal that was at least 10 times greater than the sun’s natural variation of infrared emissions. Such an intense signal, he reasoned, would be enough to stand out against the sun’s own infrared signal, in any “cursory survey by an extraterrestrial intelligence.”

He analyzed combinations of lasers and telescopes of various wattage and size, and found that a 2-megawatt laser, pointed through a 30-meter telescope, could produce a signal strong enough to be easily detectable by astronomers in Proxima Centauri b, a planet that orbits our closest star, 4 light-years away. Similarly, a 1-megawatt laser, directed through a 45-meter telescope, would generate a clear signal in any survey conducted by astronomers within the TRAPPIST-1 planetary system, about 40 light-years away. Either setup, he estimated, could produce a generally detectable signal from up to 20,000 light-years away.

Both scenarios would require laser and telescope technology that has either already been developed, or is within practical reach. For instance, Clark calculated that the required laser power of 1 to 2 megawatts is equivalent to that of the U.S. Air Force’s Airborne Laser, a now-defunct megawatt laser that was meant to fly aboard a military jet for the purpose of shooting ballistic missiles out of the sky. He also found that while a 30-meter telescope considerably dwarfs any existing observatory on Earth today, there are plans to build such massive telescopes in the near future, including the 24-meter Giant Magellan Telescope and the 39-meter European Extremely Large Telescope, both of which are currently under construction in Chile.

Clark envisions that, like these massive observatories, a laser beacon should be built atop a mountain, to minimize the amount of atmosphere the laser would have to penetrate before beaming out into space.

He acknowledges that a megawatt laser would come with some safety issues. Such a beam would produce a flux density of about 800 watts of power per square meter, which is approaching that of the sun, which generates about 1,300 watts per square meter. While the beam wouldn’t be visible, it could still damage people’s vision if they were to look directly at it. The beam could also potentially scramble any cameras aboard spacecraft that happen to pass through it.

“If you wanted to build this thing on the far side of the moon where no one’s living or orbiting much, then that could be a safer place for it,” Clark says. “In general, this was a feasibility study. Whether or not this is a good idea, that’s a discussion for future work.”

Taking E.T.’s call

Having established that a planetary beacon is technically feasible, Clark then flipped the problem and looked at whether today’s imaging techniques would be able to detect such an infrared beacon if it were produced by astronomers elsewhere in the galaxy. He found that, while a telescope 1 meter or larger would be capable of spotting such a beacon, it would have to point in the signal’s exact direction to see it.

“It is vanishingly unlikely that a telescope survey would actually observe an extraterrestrial laser, unless we restrict our survey to the very nearest stars,” Clark says.

He hopes the study will encourage the development of infrared imaging techniques, not only to spot any laser beacons that might be produced by alien astronomers, but also to identify gases in a distant planet’s atmosphere that might be indications of life.

“With current survey methods and instruments, it is unlikely that we would actually be lucky enough to image a beacon flash, assuming that extraterrestrials exist and are making them,” Clark says. “However, as the infrared spectra of exoplanets are studied for traces of gases that indicate the viability of life, and as full-sky surveys attain greater coverage and become more rapid, we can be more certain that, if E.T. is phoning, we will detect it.”

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107 thoughts on “Astronomer: use lasers as Earth’s “porch light” to attract aliens

    • We had better know where the aliens are living or we won’t be aiming well enough. This won’t be so easy to accomplish and will be very narrowly directed, and it will continue to spread no matter how well collimated.
      Sweeping the beam across the sky will not allow sufficient concentration onto any one collector long enough for much of an impact. It will appear as just another object that glittered.

    • I agree, blindly identifying ourselves could result in “things” going very badly for us. Besides, the likelihood that anyone is nearby is probably zero. The possibility of detecting anyone responding to a signal we send out could be 40,000 years if they are 20,000 light years away. This is all a big waste of time and effort. Better to wait and see if Gene Roddenberry had it right – if so, we will have to wait only a couple hundred years to have interstellar travel, at “warp speeds”…

  1. Do these guys ever watch science fiction movies?
    Have they ever read any Michael Crichton novels?
    🙂
    I understand this scientist Clark is just trying to figure out what is feasible, but please confine yourself to looking for such signals, not sending them out.

    • No need to watch/read Science Fiction just recall what has actually happened here on Earth when a more scientifically advanced race has met a more primitive one. Did the Australian aborigines or the North American First Nationers benefit from the encounter? I don’y think so. So hopefully if we do attract any space aliens they are indeed more advnced and sophisicated and don’t just treat us earthlings they same as indigenous peoples have been treated in the past.

      • harrowsceptic

        I suspect this is a genuine case for the ‘precautionary’ principle.

        Immigration is already a problem, do we really need more undocumented aliens?

        Do they even have fingerprints?

        • Don’t be daft, Robert. Any benefits gained from the industrial revolution (centuries after colonialization) happened only after extreme devastation, loss of sovereignty, and death of much or most of the population.

          • More than 80% of the native American Indian population died of European diseases without any of them seeing a European. What could we expect from extraterrestrials?

    • Have they read any of human history? We know from first hand experience what happens when a more advanced civilization encounters a less advanced civilization. It rarely(never) works out well for the less advanced civilization.

  2. Why would we want to attract aliens? What makes anyone think they would have any good will toward us? If they were really really superior would they not just think that we are some kind of bug?

    Why haven’t we already been contacted by aliens? It could be that, when a civilization reaches a certain level of technology, it invariably wipes itself out. Fermi Paradox It could also be ithat is the nature of intelligent life to destroy others (ie. us, when they find us).

    This laser alien bait is just a stupid idea and a huge waste of money.

    We want to find and evaluate them before they find us. SETI is cheaper and much more worthwhile.

    • It could be that it takes 4.5 billon years for intelligent life to develop. Then we may be the first, but not only, one.

      I think we should begin with a search for intelligent life on Earth (if you get my drift).

      • Suppose all those Sci-Fi movies of aliens taking over the world are really about humans arriving on other planets?

        BTW I know that if my first question upon meeting an alien craft for the first time would be “Are you carrying thermo-nuclear weapons?”

        • Why limit it to thermo-nuclear? I’d want to know if they’re carrying any weapons of mass destruction or if they come in peace.

          • They will always carry weapons in order to survive any hostile threats.
            The right question, Detective, is whether we humans pose a hostile threat to them.

          • carrying weapons for self-defense is one thing, carrying weapons of mass destruction is something else entirely.

          • If they plan to engage in ship-to-ship combat, any weapon is one of mass destruction. When going at light speed, a 1-gram micrometeorite impacting the hull has 10 kilotons of force. Any starship would be able to take megaton hits without significantly flinching. W

        • As humans we cannot write about truly alien species, because we cannot imagine truly alien lifeforms and thought processes.
          As such we can only write about what we know, ‘humans’ and our known behaviors and history. All the Sci-Fi novels are about how humans have behaved and are expected to behave. Aliens most probably wouldn’t want us expanding our influence through the cosmos.

          • We do have a lot of examples here on earth as example alien. Dogs, birds, dolphins for example. We know they have a language, but no matter how much we study them, we don’t know what that language is.

            An extra terrestrial may as well be a cuttlefish to us. Next to no chance of understanding them.

    • They would probably want to bestow upon us a galaxy-drive so that we can take our due place in the local-group’s galactic brotherhood of goodness and fraternity.

    • Why haven’t we already been contacted by aliens?

      how do you know we haven’t? Plenty of “real life” “alien encounter” stories out there. Could they really all be the result of fevered imaginations and abuse of mind altering substances? And don’t forget the “ancient aliens” theories.

      Or, more realistically, it’s a very huge and vast universe out there. If there is advanced intelligent alien life out there, it could be several galaxies away from us and we (and they) will never know. There’s no reason to think that there has to be an advanced civilization just a “short hop” away in one of our closest neighboring star systems.

      • Maybe the lightspeed limit is a good idea.

        If we humans had the ability to exceed the speed of light, we would be all over the galaxy. Well, eventually.

    • It’s has already been established that the vast majority of these people are living in a fantasy land. I do not expect that a rational intelligent train of thought will ever occur to them.

    • See also Saberhagen’s “Berserker” series, where an alien race, losing a war, created a self-replicating “kill everything” machine.

  3. I think episodes of “The Lucille Ball Show” spreading throughout the galaxy will make aliens think twice about visiting us 🙂

    The intent of that comment is to point out that we have been announcing our existence for 100 years with increasingly sophisticated electronic signals. What is interesting to me is that the aliens may be broadcsting signals that WE still cannot recognize. Ask yourself, would the radio signals of today have been recognized as such 100 years ago, even 50 years ago, rather than just noise?

    • 100 years ago was 1918 radio was invented in the late 1800s, so it’s possible our scientists could have spotted such transmissions as being something other than just random noise. Certainly by 1968 (50 years ago) such signals would have been spotted as something other than just random noise. Keep in mind that spotting a non-random transmission pattern isn’t the same thing as understanding and translating that transmission into something intelligible.

    • For how much longer are we going to rely on radio? Am I wrong to wonder if going to more efficient communication technologies, e.g. the internet and much more localized cellphone-tower transmissions, won’t that eventually make the Earth appear to be going dark again over the next 100 years?

      • Radar seems unlikely to be superseded in the near future. Not to mention the 50/60 Hz output from all AC systems in the World.

      • Cellphone technology is radio. Lower power to be sure, but radio none the less. So is WiFi, Bluetooth etc. Until quantum entailment technology is usefully developed, all wireless communications will use radio.

        Maybe you were referring specifically to AM/FM public broadcast radio. True, it may disappear some day soon. But we (humans) are transmitting other signals at higher power, using more directional antennas. These signals would be detectable further into space than a terrestrial radio broadcast.

    • Robert, the problem with the “Lucille Ball Show” scenario is that we have never transmitted any signals with sufficient power to be detected above the noise. Even NASA’s Deep Space Network (DSN) would be completely lost in the noise to a searcher close by (say Proxima Centauri). The point of James Clark’s study is to see if there is any feasible way to transmit something that could be detected above the noise.

      Now I would be very skeptical of the “should we” question.

  4. I think we can assume that any civilisation advanced enough to get here is advanced enough to treasure how wonderful independently evolved civilisations are.

    While sci-fi stories have aliens siphoning off our water to make their planet more habitable, the fantasy is unsustainable: comets are much easier to grab than salty oceans.

    In future when there are interplanetary conferences to trade or share technology, we could host them as the ‘juniors’ in this region. We are as yet unprepared for 150 year journeys through the nothingness.

    • While sci-fi stories have aliens siphoning off our water to make their planet more habitable, the fantasy is unsustainable: comets are much easier to grab than salty oceans

      while it’s unlikely they would try to siphon off our resources, it’s more likely that they’ll see our nice little planet as a great place to set up a colony, once they eradicate the primate vermin currently living there.

        • Or Earth could be like Jupiter in size relative to them. Indeed, I’d say there’s a greater chance of them being our size or smaller than their being mega-sized given that stress on the body structures increase as body size increases until you reach a point where the body wouldn’t be able to survive the stress.

    • No! No! No! They might look upon us as insignificant pests. Or they might look at us as useful slaves. However, who says they aren’t already here? Have you read the Hindu Bible? It reads like sci fi. And there seems to be at least 2 very good accounts that there was some sort of battle going on in the skies. One is of a painting in Germany and one in India.
      I think that if they are here, they understand our psychology very well. I have often thought that they might be the intelligence behind ‘climate change’. Just saying. The question is, ‘who do they want to kill off? the really stupid or the really bright? ‘ The really stupid are a lot easier to control. Maybe just the right amount of stupid with just enough intelligence to be useful. Remind you of any government system?
      Don’t be naive. That’s like thinking everybody’s going to get together at Hoaxahagen to solve the impending non disaster.

    • …I think we can assume that any civilisation advanced enough to get here is advanced enough to treasure how wonderful independently evolved civilisations are….

      …Just like we treasured the independently-evolved civilisations in pre-colonial Africa and the Americas….

  5. I think that’s the last thing we ought to do, we should at least wait until we have a fleet of at least 100 interstellar dreadnoughts 😉

  6. Normally I would think that this is pretty silly. But I quickly changed my mind. In fact, I think this should be the new scientific imperative. The more scientists we can wean off the global warming gravy train the less damage they can do.

  7. “a beacon strong enough to attract attention from as far as 20,000 light years away.”

    in 20,000 years time…. hello! Speed of light anyone….?

  8. What if the aliens interpret our signal as “Come eat me and please bring us some donuts”.

    If they are the distance relatives of the “Lizard People” they may like the fact that when eating us we will wiggle around a lot!

    • Or they interpret it as an insult equivalent to the alien version of “your mother was a hamster and your father smelled of elderberries” and as a result decide to teach those upstart residents of sol 3 a lesson by bombing our planet into oblivion.

      • then some idiot on the bombed out earth will reply something like “No, now go away or I shall taunt you a second time”

      • John Endicott: “bombing our planet into oblivion”

        If the aliens possessed a Ray-gun that could zap Earth’s atmosphere and break the covalent bond of CO2, it would break the Carbon Cycle of Life. They’d have a much simpler and more comprehensive method of extinguishing all life on Earth.

  9. A 2-megawatt laser? The sort of thing we use for weapons down here?

    How do you think another civilisation will react to us firing our latest weaponry at them?

    Might as well launch an ISBM at them (Inter Stellar Ballistic Missile)/////

  10. Hey, great idea, but they need to take it one step further: construct a “web” or a series of them, with high energy lasers capable of burning up anything that comes in contact with them. Then, when the aliens, who are naturally drawn to the laser light come to investigat – BZZZZZZZAPPPP!!!!

  11. Kind of like, ringing the dinner bell.
    Humans in their need to explore, could not help, and in some instances deliberately wiped out those that they met in those explorations. Whither it was for resources, or to create space for those that came after them.
    Why would it — asssuming relativity is correct be any different in this case.
    Laser beams and weird science. Nah, what a useless waste of money.
    Personally I think, the nature of the Universe as it is, causes great distances between anything that is resembling consciousness. there might be a reason for that…and so, for me. Space travel to meet, aliens or others that might be there, is impossible in this physics.

  12. How do you use a telescope with a laser?
    A laser is already a tight parallel beam, that’s the point!
    Am I missing something?

  13. “The research, which author James Clark calls a “feasibility study,” appears today in The Astrophysical Journal.

    The findings suggest that if a high-powered 1- to 2-megawatt laser were focused through a massive 30- to 45-meter telescope and aimed out into space,
    the combination would produce a beam of infrared radiation strong enough to stand out from the sun’s energy.”

    A) Telescopes, both refractors and reflectors gather light and focus it to match a person’s retina, or to match a photographic receptor/plate.
    i) shining a laser beam through a telescope in the opposite direction is roughly equivalent to a plain flashlight with the light spreading out. Meaning the infrared emissions will lose power rapidly. Leaving it unlikely to be recognizable at our solar system limits.

    B) As other have noted, such a “announce Earth creatures program” is akin to ringing a dinner bell.
    i) Life consumes life; except for the lower more basic Earth organisms; e.g. lichens, bacteria, fungi, algae, etc; where the organisms can derive sustenance from elements and nutrients in solution.
    ii) Any interstellar life that recognizes James Clark’s “porch light” is far more likely to consider themselves far superior to Earthlings. Notifying them that Earth can serve as a source of sustenance for deep space travel is a bad idea.

    C) The ‘Star Wars’ and ‘Star Trek’ fantasies have bemused and bewildered substantial portions of Earth’s population with ‘lion lies with the lamb’ stupidity.
    i) Any higher order creature visiting Earth is more likely to view Earth as a planet sized meat farm filled with chubby soft creatures.

    D) Any such program announcing Earth to extraterrestrials must require 100% agreement from all of Earth’s citizens.
    i) Earth is already noisy enough over a very large bandwidth of radiation, that there is no need to add in a blinking light to further entice aliens.

    • ATheoK

      Any higher order creature visiting Earth is more likely to view Earth as a planet sized meat farm filled with chubby soft creatures.

      Hey!……….speak for yourself.

      Besides, they might be vegans.

  14. Apparently no other intelligent have thought to do the same or similar things. There might actually be several explanations. One possible explanation is they are not there?

  15. You’re all decades too late. The invitation was sent out via Voyager:
    https://voyager.jpl.nasa.gov/golden-record/
    Fortunately, it was in the form of a golden LP gramophone record. The invitation to dinner or whatever would only be intelligible to primitive civilizations who still use record players. However, it would make a nice frisbee for alien kids to toss around presuming that the alien world had an atmosphere.

  16. The only reason we’re here is because at some fundamental level the universe has a structure to bring about our existence & that means there are many more of us or something similar to us out there (the evidence for this is that we are here). Why haven’t we found these others you ask, I don’t know but that doesn’t mean they aren’t out there somewhere

  17. You must first sign the agreed upon position statement warning of human-caused global warming before we can continue with discussions and public announcements. It’s a minor formality really. Some mention of moneys for NY subways and high speed rail in California would also be a nice add-on bonus.

  18. We don’t actually know much about stars, we only have very weak theories with no alternative ideas, because all of the money goes into existing interpretations, there will be no other solid theories, cos money and dogma

    If IF stars manifest events every few million years or longer, that sterilize solar systems, it would explain why we find nothing so far.

    It would also explain why we’ve not seen some super advanced alien race that’s been around god knows how long.

    Also, putting an “age” on the universe with even a quantum of certainty, is the most arrogant deluded thing a scientist can do.

    We don’t even have a clue how old earth is, all age estimations come from the absolute bollocks interpreted from Hubble’s work.

    This iteration of life on earth may not even be the first, or second, or third, all we have is best guesses, posing as some sort of solid theory, nope. We operate on a skin on the planet, a skin that could have been stripped away repeatedly over who knows how many billions or even trillions of years. The junk from this is readily apparent in and around the solar system, and there is nothing even remotely solid to suggest that detritus is from the early days of the solar system, dogma apart.

    • Mark – Helsinki,

      Sadly you are quite un-informed.
      We have a pretty precise age on the sun: 4.57 (+/- 0.05) Billion years (Gy). For reason of hard stellar physics, this is when the sun began it’s main sequence life.
      Once the sun started shining, its solar wind began to sweep away the microscopic dust cloud that cocooned the forming proto-planets, stopping their further dust driven growth.
      Of course, then a shooting gallery of gravity assisted protoplaneatary collisions and comet bombardments from the deep cold reaches carried on for hundreds of millions of years. Before things began to settled down a bit by 4.1 Gy ago.
      There have been some research groups reporting that signs of the earliest life appears in some ancient rocks with about 200 millions years, or about 3.9 Gy ago. The sun was still quite weak compared to present, but a higher atmospheric sea level pressure could have been the compensation to keep the planet surface warm enough to keep the sea unfrozen while volcanos kept spewing gases and forming island chains. Plate tectonics may not have begun until the Earth was about 1 Gy old due to the need for water to get deep enough to lubricate things on the thinner crust present then.
      All these things are pretty well understood. Especally the ages. There are still a lot of details that are speculative, like when exactly did tectonics start, and what was the path between sterile palanet and abundant microbial life. The RNA world hypothesis as precursor pathway to complex life, is just that, an unproven hypothesis, and probably will remain so.

      But please, don’t let me stop you from willful ignorance.

  19. No one would see it anyway. A laser through a telescope is very directional. Where would you point it and for how long? Maybe if you could attract a giant Space cat to chase after the dot, you could at least post the video on youtube and get a lot of hits. It sounds like a waste of money, it would be a perfect project for Scientologist or some other group with more money than brains.

  20. Proxima Centauri is an M-class dwarf star, a stellar mass of about 0.24 solar mass. It is a bad boy. It regularly bathes its known rocky exo-planets with stupendous blasts of sterilizing radiation from x-ray flares and potent CMEs.

    If we ever find life in another system, it will likely have to be a well behaved unitary star, in 0.9 to 1.1 solar mass size range, with a similar metalicity to the sun, and in its main sequence mid-life, and in a “safe” backwater neighborhood of the galaxy like our system.
    That rules out a lot of systems. But there are still some candidates within 40 ly.

    The Star Trek paradigm where there are evolved highly complex life in so many systems is of course fantasy. But the general public is ignorant enough of the realities involved to not understand that highly complex life beyond some microbial laden sludge near a mineral hot spring is most certainly exceedingly rare, like 1 in a billion or more rare. In that likelihood, Cap’n Kirk and his merry band would have spent their entire 5 year mission finding nothing but dead, radiation blasted rocks orbiting around bad boy stars, many of which are binary gravitational slingshots.

  21. Considering that homo sapiens has been on this planet for 150-200k years of hundreds of millions of years that life has been around, what is the likelihood that any species in another solar system will evolve and reach technological parity or superiority at or near the same time as us and would be able to communicate with us or travel here considering interstellar distances, the limitations of light speed and sub-light speed limitations of spacecraft? This idea is a perfect example of wasting resources to pursue the ridiculous by failing to properly analyze statistical probability and/or our limited abilities. Sheesh.

    Could there be grant money involved in this POS pursuit?

  22. To represent humanity to the galactic community, NASA sent the Pioneer plaque showing a man and Barbie doll! The woman has no genitals. The aliens might get excited and come to Earth to reproduce. NASA thought we better replace woman with Barbie doll

    https://i.imgur.com/uahJN3x.jpg

  23. UFO travelling past our solar system, minding its own business, when.. BZZZZZAP!

    “Ouch. Those Earthers sure are aggressive. Lucky we had our shields up or we’d have been fried.”
    “Yeah. Let’s give them a dose of their own, see how they like it!”
    “OK, charging the space cannon..”

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