So, the media is abuzz about a BLC1, a candidate signal around Proxima. I’ve been all over Twitter about this, so I’m collecting my thoughts here.
But first, a disclaimer: as a member of the Breakthrough Listen Advisory Board and a Breakthrough Listen member’s current PhD adviser, I have a little bit more information than the public than this, but I am not a BL team member and have not seen the data. My comments here are purely general and, while they can provide context for what’s going on, they do not actually add anything to what’s known about the actual candidate signal beyond what is already in the press.
First, how does radio SETI work?
The Breakthrough Listen team uses radio telescopes to look for signs of radio technology in the form of (among other things) narrowband radio signals of the sort that can only be caused by technology. This is the sort of thing they’re looking for:
This is not the data from Proxima, it is an example.
This plot, from Howard Isaacson’s paper on the topic, shows the actual signal of extraterrestrial technology beaming a radio signal to the Earth. In this case, it’s not aliens: it’s Voyager II.
The vertical axis is time, going up. Each bin is 10 seconds or so. The horizontal axis is frequency, and each bin is a few Hz. Note a few things about this signal:
- At any given moment, almost all of the power is concentrated into a single frequency bin. This is how we know the signal must be artificial. Radio signals from space come from electrons or atoms or molecules, which always have some temperature. They also tend to come from large clouds of gas, which have lots of internal motions. Both thermal and bulk motions generate Doppler shifts that blur out the frequencies they radiate at. Even the narrowest masers, like water or cyclotron maters, must have widths 4 orders of magnitude broader than the signal above.
- The signal is not perfectly narrow band. There are two faint “sidelobes” visible on either side (there are bigger ones, too, outside the plot). This is due to signal modulation, illustrating that the signal contains information—it is not a pure “dialtone” or “doorbell”.
- The signal’s frequency is shifting towards lower frequencies as time increases (upwards). This is how we know the signal is not from Earth: the telescope is on the Earth, which is rotating. As this happens the telescope is first moving towards the source (as the source rises), then moving away (as the source sets). This creates an ever increasing redshift, making the signal “drift” to lower and lower frequencies during the observation. A source on the surface of the Earth would not be moving with respect to the telescope, and so would show no Doppler shift.
Note that this shift is the change in the Doppler shift—we can’t calculate the total Doppler shift without knowing the transmission frequency.
The problem is that the spectrum is filled with these sorts of signals. Every now and then one is from an interplanetary probe, but most are from Earth-orbiting satellites and terrestrial sources. Breakthrough Listen employs sophisticated software that sorts through the millions of signals they can detect and find the ones from space. The way the team rules out signals from anything other than their celestial object is by nodding the telescope. If the signal is from something on Earth, then they’ll see it no matter which way the telescope is pointing. If it’s from space, it will only appear when they are pointing at the target. For instance, here’s a pernicious false positive from Emilio Enriquez’s paper on the topic:
This is not the data from Proxima, it is an example.
This signal is apparently modulated in a nasty way: it was strongly detected only when they were pointed at the star HIP 65352 (the first, third, and fifth rows) but not when they pointed away (in the second and fourth rows). It also has a slight drift: the signal has shifted by a few Hz by the end of the series of observations.
But, you’ll notice, the signal is also present in the off pointings. It’s very weak then, below their threshold I suspect, which is why the algorithm flagged this as interesting. But if it were really coming from HIP 65352 there’s no way it could be present in those off pointings. This is probably something terrestrial with a poorly stabilized oscillator putting power into the sidelobes of the telescope or something. The exact nature of this signal is not important—all that matters for SETI is that it is not from HIP 65352.
And the radio spectrum is filled with these sorts of false positives! Sifting through them all is hard, and takes a lot of time, and has trained the team to get very good at identifying radio frequency interference. Indeed, no signal has ever survived the four tests I described above after human inspection: narrow band, drifting signal, only present in the on pointings, never present in the off pointings.
Until now!
What did the team find?
The Breakthrough Listen project uses the Parkes radio telescope in Australia as one of its tools to search for technosignatures. In this case, they were “piggybacking” on observations of Proxima, the nearest star to Earth, which were looking for radio emissions from stellar flares. These were long stares for many hours per day, for many days. The signals they were looking for are broadband, with complex frequency and temporal structure—basically, if you tuned into it with a radio receiver like the ones we use for FM or AM transmission, it would be present at every frequency, and sound like very complicated static.
But the equipment on the telescope can also be used for SETI, and so the BL team was using the telescope “commensally” to do a SETI experiment simultaneously to the flare study.
And in these data, a signal has apparently survived all of their tests!
Now, this does not mean it’s aliens, as the team has pointed out. It means they have, for the first time, a signal that can’t be easily ruled out as RFI. It’s probably RFI of some pernicious nature, but we don’t know what. Pete Worden of the Breakthrough Listen team says it is “99.9% likely” to be RFI.
We know the signal was present for around three hours, present in 5, 30-minute “on” pointings and not at all in the interspersed “off” pointings. We also know it has a positive drift rate, it appears at 982.002 MHz, and that it appears to be unmodulated.
Other than that, we don’t know much! But there are some things we can conclude based on this little bit of information.
Why isn’t the team releasing more information?
I cannot speak for the team but I know they’re committed to transparency and scientific rigor. They also think hard about how to convey results to the media, and are careful about things like press releases and peer review of results.
Unfortunately, this news leaked out before the team had finished their analysis, so we’re left to read tea leaves and parse vague newspaper statements instead of reading their paper on the topic (which does not exist because they’re not done with their analysis!)
Someone in the “astronomical community” (we don’t know if they are even a member of the team) leaked the story to the Guardian. Their hand having been forced, the team then gave interviews to Scientific American and NatGeo with some more details, emphasizing that the signal is probably RFI.
Now, I’m pretty grumpy about this. SETI has extensive post-detection protocols that were not followed by the leaker, exactly to avoid this sort of situation. Especially since the team was definitely going to announce this, there’s no need for the leak.
But really what I’m grumpy about is that the team did not get to announce this on their own terms in a way that made clear what was going on. Instead we have lots of speculation and questions that not even the team can answer (because they haven’t finished their analysis yet!)
So what are the odds it’s aliens?
As Pete Worden tweeted:
Read what we said! No one is claiming it’s A techno signature. We are in the process of following the agreed protocols. At this point we have some interesting signals we believe are interference but as of yet have not been able to track down the source.
— S. Pete Worden (@worden) December 19, 2020
And in the SciAm article:
“The most likely thing is that it’s some human cause,” says Pete Worden, executive director of the Breakthrough Initiatives. “And when I say most likely, it’s like 99.9 [percent].”
What should we make of the fact that the drift rate is positive? Isn’t that the opposite of what we expect?
It’s unclear how to interpret this.
The fact that it drifts at all is consistent with a non-terrestrial origin. The fact that it drifts more than you’d expect from the motion of Parkes by itself means that the source is either “chirping” its signal to go up in frequency, or that it is not correcting for its own acceleration, and it is accelerating towards the Earth (not directly towards the Earth, like it’s coming for us or something, but just that we’re in the same hemisphere of its sky as the direction it’s accelerating).
Some SETI practitioners expect that a signal would be non-drifting in the frame of the Solar System barycenter, meaning that after we correct for our motion, the signal would have just one frequency. This defies that expectation.
It also can’t be from the rotation of a planet that hosts the transmitter—those shifts would also be negative. But it could be from the orbital motion of a planet, or from a free-floating transmitter, or from a transmitter on a moon.
The most likely explanation is probably that it is a source on the surface of the earth whose frequency is, for whatever reason, very slowly changing.
Until we know more about the drift, though, there’s not much we could say.
Are we sure it’s coming from the direction of Proxima?
Not completely. If it’s ground-based interference, it’s definitely not coming from that direction. If it’s really from space, it could actually be coming from any place in a 16 arcminute circle around Proxima—about half the width of the full moon.
What do we make of the frequency?
I’m no expert, but apparently 982.002 MHz is in a relatively unused part of the radio spectrum, where there is not a lot of radio frequency interference. It is in or near what radio astronomers call L band (I guess it’s technically UHF because it’s below 1 GHz), which has long been favored as a place to do SETI because it is in the broad minimum between noise and opacity from the electrons throughout the Galaxy and Earth’s ionosphere on one side, and that from water and other molecules in Earth’s atmosphere, and the cosmic microwave background on the other.
From seti.net. The x-axis is in GHZ, so 982 MHz is just to the left of the 1.
It’s also not far from the “water hole” favored for a long time as the place to look in radio SETI.
Some have pointed out that the signal is suspiciously close to an integer value of MHz, which would argue for a terrestrial origin (since aliens presumably would not use Hz as a standard. The deviation from an exact number of MHz is also consistent with imperfect oscillators in typical radio equipment).
The articles mention Proxima b. Could the signal be coming from that planet?
Maybe? Until we know more we really can’t say. The team itself does not appear to have favored this idea (it seems to me to have come from the authors of the newspaper articles) and indeed they have privately communicated to me that they have not analyzed this possibility because they’re focused on the RFI origin right now.
We also don’t know the orbital inclination or rotational properties of Proxima b, so we don’t know what acceleration signal it would provide. Without a good model for that planet and without knowing what the team has seen, we can only speculate.
That said, if the signal repeats and turns out to be from Proxima, and if the signal is not being inherently modulated, then we could use the drifts to infer the accelerations of the transmitted, and possibly determine whether it’s on the surface of a planet, and determine the rotational and orbital period of that planet.
But seriously, isn’t it horribly unlikely that of all places the first signal we’d find are from the nearest star, Proxima?
The original Guardian article had a misguided take on this one:
“The chances against this being an artificial signal from Proxima Centauri seem staggering,” said Lewis Dartnell, an astrobiologist and professor of science communication at the University of Westminster. “We’ve been looking for alien life for so long now and the idea that it could turn out to be on our front doorstep, in the very next star system, is piling improbabilities upon improbabilities.
“If there is intelligent life there, it would almost certainly have spread much more widely across the galaxy. The chances of the only two civilisations in the entire galaxy happening to be neighbours, among 400bn stars, absolutely stretches the bounds of rationality.”
This is wrong, because it’s based on a lot of unexamined priors and assumptions.
First, it assumes that signals of this sort must be very rare coming from only a handful of stars in the Galaxy. While that is certainly very plausible, the idea that nearly every star might have some sort of technology around it is older than SETI itself! Indeed, it is at the heart of the Fermi Paradox, which asks: since interstellar spaceflight is possible with ordinary rockets, and since the Galaxy can be populated by such rockets in less time than it’s been around, why aren’t aliens here in the Solar System right now?
One answer is “they don’t exist.” Another is “they don’t spread around very much”. Another is “they are most places, but avoid the Solar System for some reason, perhaps because life is present here.” Another is “they have been here in the Solar System but aren’t here now.” Another is “there is alien technology in the Solar System but we haven’t noticed it”.
Dartnell’s “improbabilities upon improbabilities” presumes that the second answer above is correct, but there is plenty of heritage in the SETI literature that explores the other answers, as well.
But even if it’s true that interstellar travel of creatures is rare and Parnell is right that it’s therefore unlikely that Proxima is inhabited, there is still a good argument to be made that Proxima is the most likely star to send us signals—perhaps even the only such star!
If there exists a Galactic community, either a diaspora or a lot of stars with technological life, or even just a single planet with life that has sent its technology everywhere, then it might set up a communication network. This is, after all, what SETI hopes to find.
But when you want to communicate with many places over very large distances, point-to-point communication is a poor way to go about it. When you call your friend on your mobile phone, your phones aren’t sending radio signals to each other. That would require way too much power and complexity. Instead, your phone sends its signal to the nearest cell tower. This makes the power requirements of your phone (and the tower) much more reasonable. This tower then sends the signal, via many means, on a complex route through many central nodes until it arrives at your friend’s nearest cell tower, and they get the signal that way.
By this logic, Proxima is the most likely place for the “last mile” portion of any message to the Solar System. Indeed, it may be the only star transmitting to us!
And note that this scheme does not assume that the message is meant for us—the Solar System may just be one stop in a network.
But if they were trying to get our attention, then they need to do something we would find obvious to look for, which means they’d have to guess which stars we’d guess to search for their signal. There are a lot of stars to choose from—which is the most obvious place for us to look? It’s hard to argue for a better target than Proxima.
Now, this could all be wrong, but the point is we don’t know what sort of luminosity function or spatial distribution transmitters might have, and it’s easy to construct plausible scenarios where Proxima or some other very nearby star is the first one we’d detect.
So what could it be if not aliens?
I don’t really know. I’m not an expert in RFI, and even if I were, I haven’t seen the data.
Jonathan McDowell and I have had some fun on Twitter exploring an interesting possibility:
Anything in Molniya orbit is going to spend time at -63 deg moving slowly at apogee, but not sure if any are L-band. Russian GLONASS nav sats are L-band and in 65 deg orbits but 12hr circular, so wouldn't stay in the beam as long.
— Jonathan McDowell (@planet4589) December 19, 2020
There’s a special kind of orbit that takes satellites way out to +/- 63 degrees declination and sort of hang there at apogee for a while in a long elliptical orbit. Such satellites would also have a positive draft rate, since they’re accelerating towards the Earth. Jonathan, who keeps careful track of everything artificial in space (literally) has been trying to see if any actual satellite might do this in the direction of Proxima, but he didn’t find any in his database.
So what’s next?
Mainly, we wait for the team to finish their work and present their results.
Things that I imagine the team are and will be doing include:
- Pointing Parkes at Proxima a lot to see if the signal repeats! Unfortunately, there are not a lot of facilities in the Southern Hemisphere that can do this work. MeerKAT may be up to the task soon, but is hard to get time on. Depending on the strength of the signal it may be possible to point smaller telescopes at Proxima to search for it as well.
- Scouring all of their data for other examples of this signal. If it’s RFI, there’s a good chance they’ve seen it before when not pointing at Proxima
- Searching carefully for other signals from Proxima. If there is one signal, there may be many more.
- Considering lots of sources of RFI—what devices transmit at 982 MHz? Could any satellite or train of satellites stay in the Parkes beam for 3 hours? Could it be a hoax?
If it never repeats and if the team can’t find a good RFI explanation then I’m afraid it will be another Wow! Signal; an intriguing “Maybe?” that we’ll just have to wonder about forever. We can’t study it if it’s so ephemeral that we never get a good look at it again!
But mostly, we talk about how cool SETI is and we wait!
I am passionate about SETI but have believed for some time now that they’re wasting their time searching for radio waves or fast radio bursts.
Photons and neutrinos will be the basis of the vast majority of communication by alien civilisations. Like us they probably used radio waves for a period, once. Long since passed through our planet. And any that do come from planets at our stage degrade to nothing long before they get here anyway. Once we start seriously looking at neutrinos in a certain way, we will go from scratching our heads at why the universe is so silent, to not even being able to keep count of the number of alien civilisations we become aware of. Of course we’re just not at that stage yet. But when we get there.
Neutrinos do not degrade. Pass through all matter at near light speed unlike radio waves. The only current reasons against neutrino based communication people retort with are current technological constraints, they are absolutely the go to communication medium for technologically advanced civilisations, when you look at every property of them.
I understand SETI folk’s reasoning for wanting to look at FRB’s but when civilisations reach the level advancement where they would be capable of sending fast radio bursts across the galaxy (or universe) with the energy levels required, there’s no reason they’d not just be using neutrino based communication in it’s place (or indeed light e.g. causing variations in their stars, but that probably takes much more hassle than neutrino based comms)
1. The signal passes the standard tests for off-world signals. Period.
2. The Doppler shift is ‘clean’ and steady, thermal drift is unlikely to be that consistent.
3. It was around the same spot in the sky for three hours. Which rules out most all mobile sources.
4. The stored data does not have the resolution to make any statements about the modulation or not of the signal. It’s just doesn’t have the resolution for that. Perhaps, if it repeats, they can keep the raw data for a change.
5. Whilst I appreciate scepticism, we seem to be apply somewhat arbitrary and narrow human standards, in a pretty non-scientific way as the only ‘proof’ that this is a human generated signal, even though several of the standard test are there specifically to avoid those issues.
6. Science should be about accepting what we actually know, that is scientific proof. As many have stated, it’s closeness to a integer of frequency is either a coincidence, as Hz is a human invention, not a scientific one, or intentional on the part of the sender, which would seem more likely to me.
7. It concerns me that on top of the standard accepted tests, which this signal passes, it’s seemingly discounted due to a human ‘feeling’ that it’s too close to a specific frequency. So what, that doesn’t necessarily mean anything at all, and it would be extremely bad science to rely on that to disprove the signals origins in light of the multiple other scientific evidence that says it’s a good signal.
8. Also, I’m exasperated by the idea that it’s really really unlikely to be real as it’s really really unlikely that our nearest neighbour would harbour intelligent life. This is wrong on so many levels. The most likely place for us to receive any signal would be our local stars. And would become exponentially less likely for stars further away from us. This is simply due to the strength of the signal required for us to receive it, means it’s far more likely we would receive a signal from a nearby star, which I guess is why they where looking that way to start with. Now they have found something, it’s suddenly proof that it can’t be a real signal? That makes no sense. I remember when the scientific consensus was that planets where rare. We now know that most start systems have planets, some with many planets.
9. It is also really apparent we judge other life with something other than an even measure, as we use the lack of their interplanetary travel as proof that aliens don’t exist. Whilst at the same time, we go nowhere ourselves. How many stars have we sent even a probe to? None. We could, but we don’t. The Voyager probes have only recently entered interstellar space, it took decades for them to get there.
10. Science should look at these signal with a scientific view, based on it’s properties, not on our biased human scale. I think then you would have to accept the signal as real and the real scientific analysis can begin, no this pseudo scientific opinion, which actually adds nothing of value, proves and disproves nothing and actually damages true scientific evaluations of the evidence.
Any news concerning BLC1? Will the paper be published soon?
Good grief….right here
“What a twist”
So are they still planning the April 29, 2021 observation for the signal from Proxima at the Parkes Observatory?
The Flare-Type IV Burst Event from Proxima Centauri.
How small is the possibility that this was the techno signature of a star ship being launched by laser towards Earth?
Any thoughts on Zic et al. (2020)? https://arxiv.org/abs/2012.04642
They were looking at the same star roughly at the same time (+-2days) and at wavelength ranges including that of BLC1. Any hint of it in the ASKAP data? Any thoughts on whether it could have the same source as the emissions they describe? Any correlation with optical data?
28 Jan 2021 | 16:00 GMT
Breakthrough Listen Is Searching a Million Stars for One Sign of Intelligent Life
The world’s largest SETI effort is scanning the skies with AI.
By Danny Price
https://spectrum.ieee.org/aerospace/astrophysics/breakthrough-listen-seti
It will be interesting to see the two papers, much easier to deny and say RFI then to shock the public…
The amount of abuse I just received on a Seismology twitter site about Total Solar Eclipses causing earthquakes, maybe it is best to blame it on RFI, I felt like they where coming to burn me at the stake!!!
E.T. signal from Proxima Centauri? A conversation with Breakthrough Initiatives’ Pete Worden.
https://www.space.com/proxima-centauri-signal-breakthrough-listen-pete-worden-interview
“Worden: We’re about to submit our papers on the signal. We’re virtually certain now that it’s interference. I can’t get into the details. However, our intent was that this was kind of a pathfinder, so we’re happy with the opportunity. It’s the first signal that passed our basic test.”
No, now that I’ve seen the data I’ll let the BL team to all of the talking. Papers generally take weeks-months to write and get reviewed, so don’t expect anything very soon. But I would think definitely before summer.
> Also, I’ve now seen the BLC-1 data and so now I understand why they say it’s most likely radio frequency interference from Earth. I *really* wanted it to maybe be an alien signal, but now that I’ve seen the data I agree 100% with their analysis.
Prof. Wright. Thank you for this, AFAIK this is the first time someone other than the team who has looked at the data has stated their opinion on it, so you can imagine how tantalizing that is. Do you have any more information about why you came to that conclusion? Alternatively, do you know anything more about when that data will be published?
Is there any update on when a research paper will be available for the public?
Ok, so this frequency 982 MHz, that is protected by international agreement and used only for military/FAA TACAN/DME equipment has now been identified??? It seems rather odd that these are the frequencies that Edward George Bowen developed in Australia in the1940’s with the USA for DME. “In addition to developments in radar, Bowen also undertook two other research activities: the pulse method of acceleration of elementary particles; and air navigation resulted in the Distance Measuring Equipment (DME).” Edward George Bowen was also the main contact and information source for the Tizard Mission which brought the cavity magnetron from Britain to the USA in September 1940 and further developed by MIT. A cooperative project to develop a high power light weight radar and comparable to the Manhattan project in its early ending of WWII.
This same man also encouraged the new science of radio astronomy and brought about the construction of the 210 ft radio telescope at Parkes, New South Wales. During visits to the US, he met two of his influential contacts during the war, Dr. Vannevar Bush who had become the President of the Carnegie Corporation and Dr. Alfred Loomis who was also a Trustee of the Carnegie Corporation and of the Rockefeller Foundation. He persuaded them in 1954 to fund a large radio telescope in Australia with a grant of $250,000. Bowen in return helped to establish American radio astronomy by seconding Australians to the California Institute of Technology. Bowen played a key role in the design of the radio telescope at Parkes.
It also seems very strange that many of the scientist and that were involved in the early development of radar where also involved in UFO research.
You will have to excuse me but on a more personal note my father Charles W. Fidler was also involved in RADAR during WWII, with its use in the pacific theater of combat. I was also in the Air Force under NORAD at the 25th NORAD SAGE site at McCord AFB near Tacoma, Washington and at Air Force radar sites in Alaska and on the Tonopah ranges in north central Nevada. I worked for the FAA as an Air Traffic Controller for 24 years and was familiar with TACAN/DME and radar system coverage in the USA.
As I have told you before high power radar has been beaming signals out since early 1943 in a continuous rotating horizontal beam 24 hours 7 days a week from every surveillance radar on the face of the earth. These beams are directional and much more powerful then TV, radio and any other radar systems in coverage of signals sent into space.
All I can do is give you my best opinion. I already have tenure so I’m free to speak my mind. Also, if there is evidence of alien life out there it’s a guaranteed Breakthrough Prize (bigger than the Nobel!) so I would have every incentive to promote it.
And indeed of all astronomers I know Avi is the one least concerned of what other astronomers think of him. Love him or hate him, when he speaks you always get exactly what he actually thinks on a subject.
Also, I’ve now seen the BLC-1 data and so now I understand why they say it’s most likely radio frequency interference from Earth. I *really* wanted it to maybe be an alien signal, but now that I’ve seen the data I agree 100% with their analysis.
I know that’s not the result you want to hear, but it’s true.
Well you should know, she is one of your colleagues…
Lets see, a flawed report by Avi Loeb which totally ridicules the idea of a signal and how we are not at the center of anything. Every article on the subject says no it’s not real over and over. I realize that your reputation and standing in the scientific community is important and the UFO black hole event horizon may destroy your careers, but the bias is obvious and I have lived thru over 50 years of denial and bias on this subject. It seems to me the science/astronomy community is still living in the dark ages with the fear of punishment by the rest of Academia. There has been a very concentrated effort to destroy free speech on this subject since the end of WWII. This is a sad situation and why we have people controlling humanity like Trump, a half a million deaths…….
I don’t think you can read much into this, and it’s not at all a bizarre coincidence. The reason the signal was seen on that night is that is when they were scheduled on the telescope! They were monitoring flares on Proxima simultaneously with optical telescopes, and that time if year is when optical telescopes can observe Proxima the longest—from early evening to early morning.
They did not monitor Proxima in the same way during other times of year.
A very bizarre coincidence between the timing and position of earth in its orbit is when this signal arrived from Proxima Centauri, this HAS NOT been commented on by the astronomy community! The possibility is that intelligent life is common and the BLC1 signal is the galactic communities introduction to a virgin civilization. Why else would the signal be received at midnight on the only night the earth is closets to Proxima Centauri. They know we are here and they have for a long time. Think about it, this happens only once a year every year at midnight on April 29 for Proxima Centauri!
Why do you think Astrophysicist Sofia Sheikh from Penn State University is going to be looking for the same signal on April 29, 2021?
This is why I favor the possibility of a galactic community that may have signal beacons near our solar system in our galaxy. These transmitters would send out the signal at specific times that coincided with near passage of the earth each year to the nearby star systems. The shock effect on civilizations would be greatly reduced if time and location precise signals with only limited, dull, low data information was sent…
The work by Amir Siraj and Abraham Loeb; “The Copernican Principle Rules Out BLC1 as a Technological Radio Signal from the Alpha Centauri System” has a rather large flaw in it. The stars included in the article have an effective temperatures between 4800 K and 6300 K. This only covers the Main Sequence dwarf stars from F8V through G to K3V and leaves out all stars from K4V to M9V. The K4V to M9V includes close to 90% of all of the oldest stars in our galaxy. This make the study biased toward favoring solar G type stars and is not following Copernican Principle Rules.
In other words Proxima Centauri a M5.5V star, cannot have a beacon on it’s planets because it is not included in the stars in this study.
Correction to my last post; “single dish would be 1275 m.” and gain is about 82 dB.
I did a quick sanity check on the transmitter’s power. I used 1000 Watts with an antenna beam-width of 1 minute of arc (Parkes is 15 minute of arc). A single dish would be 2550 m (Arecibo is 305 m and Parkes is 64 m). With everything at 100% efficient and no losses the power at the Parkes’ antenna aperture is 3.06e-20 Watts.
Source transmit power – the receive parameters of the Parkes antenna are known. If the power level of the signal was recorded some assumptions could be made as to the source transmitters power. Depending on the transmitters antenna configuration, gain and beam-width the power could be bracketed. I suspect using a modern high gain antenna with a narrow beam-width the power could be less than 100 watts. Otherwise thousands of watts. Voyager 2’s transmit power is 20 watts.
Its All fake
Any idea when they will release???
https://tenor.com/view/mr-bean-waiting-still-waiting-gif-13052487
Shouldn’t there be some discussion about who leaked this story to the Guardian. Do we know if they were on the team? Seems like if wasn’t just for publicity, not worth it.
I don’t know, the team hasn’t released this information yet.
What is the estimated transmit power/watts of the signal at the source (if coming from Proxima Centauri)? Similarly, what would be that number originating near earth? In addition to frequency (Mhz), power would indicate candidate sources.
I am a southern California retired engineer and have been doing research on “radio sun” at 2800 MHz with comparisons to NASA GOES X-Ray Flux and flares. I have an antenna/receiver setup and do daily 24 hour recordings.
I recently switched over to 982.002 MHz and looked at the signal. It is very similar to 2800 MHz. The sun’s signal dies out after sunset and comes alive at sunrise. It peaks at “solar noon”. At 982.002 MHz and 2800 MHz I do see an occasional aircraft transponder “chirp” as they pass overhead.
Proxima Centauri does not appear in my sky as I am at 34° north latitude. I trust there are amateurs “down under” looking at the sky for possible 982.002 MHz signals.
There is nothing special about the frequency’s odd number as it might be transmitted using a different time base. Or in my case I shift frequency slightly to get best antenna/system performance.
Good reading is the Parkes Users Guide especially paragraph 1.9.4 – Interference & Avoiding RFI.
In case you are confused, I’m using UTC with the date of Earth’s closest encounter (midnight culmination) to these stars just after midnight of the early morning of the 12th of January for Luyten’s Star and early morning on the 15th of January for Procyon.
Well, after looking at Luyten’s Star and it’s four planets midnight culmination just after midnight on January 12th, I did not think Procyon A and B, being only 11.4 light years away, would be very habitable. Now, after looking the data on the star Procyon being a F5V and its white dwarf companion I noticed that it is only 1.2 light years from Luyten’s Star. This is interesting, and both star systems are only 3 degrees apart and have only a 34 seconds difference in latitude in our night sky. Procyon midnight culmination happens on the 15th of January and may be worth looking at for a signal since any civilized presence on Luyten’s Star may have found its way to Procyon.
Seti is All covered Up. And this is leak… maybe our first leak after 50 years.someone took IT out from project 2019 and talked. Maybe girlfriend or boyfriend whatever. we got leak of MHz and 3 hours of signál. Looks like signal from aplha is here for long time and this is first leak after someone went crazy. This is great.
Hi
We All need your Brains. I just Seen Ufo in 39week 2020 at 16:30 IT was All like Mirror watching us…..right before sunset when the light IS bouncing from the shields. They are sun powered like oummuamua.
Why u didnt post my comentary
As you write, it is first positive, then changes towards negative, so the *change* is in the negative direction, the whole time.
Very interesting for a noob like myself but I haven’t understood from explanations why the doopler shift should be toward lower frequencies always.
I first guess orbital distances changes as earth or source orbit their star is something of neglectible order compare to earth/source distance itself … But if signal rises and sets in telescope pointing then shift should be positive and then negative and all related to earth rotation speed, no?
I need more clues for why it has to be negative shift.
Well, after checking my calculations it looks like the date may be the 12th of January for Luyten’s Star date of midnight culmination. I have been travelling and resting after a long tiresome day trip for our monthly grocery shopping so may need to check. Here is the screenshot of Stellarium for date and north latitude of
Luyten’s Star.
https://ibb.co/3NCcTD3
If and that is a big IF this is the way the galactic community introduces itself to a virgin civilizations, the date of closet encounter distance to a star of the earth in our yearly orbit around the sun, other stars with planets may also send a signal on there date of culmination at midnight. We may want to monitor these stars on those dates to see if a narrow band signal is present. Now looking at nearby planetary systems there is one that will take place tonight the 8th of January: Luyten’s Star with 4 planets and 12.2 lightyears distant.
https://en.wikipedia.org/wiki/Luyten%27s_Star
Habitable Planet Reality Check: The Nearby GJ 273 or Luyten’s Star.
https://www.drewexmachina.com/2017/03/20/habitable-planet-reality-check-the-nearby-gj-273-or-luytens-star/
Now anyone with a large radio telescope and some free time on it around midnight may want to monitor it tonight for narrowband signals. This star is 5 degrees north so good radio telescope coverage in both hemisphere’s. Best of luck and more to come!
I hope you realize what this means? The signal would of had to been sent at such a time that it would be received when the earth in our solar system was closest to Proxima Centauri. ;-}
Let me state that a little differently, the transmission from Proxima Centauri was sent 4.25 years earlier and they knew that the day the earth was going to be in the position to receive it exactly at midnight when the earth was closet to Proxima Centauri.
Looking at Stellarium 0.17.0, they do have the Parkes Observatory location listed and setting it up for April 29 to May 2 puts Proxima Centauri at its highest point in the sky at midnight. One and one half hour each side of that time keeps it at a height of 57 degrees 39 minutes to over 60 degrees above the horizon for the full 3 hours. This means its was 30 to 32 degrees from the zenith, so a aircraft, drone or satellite would be circling for 3 hours centered around midnight almost directly over the Parkes Radio Telescope…….
This would make it much more difficult to do then if the scope was pointing toward the horizon where someone could be using an aircraft or drone from miles away!!!
Here’s a very ‘out there’ idea. I note that Proxima Centauri has a small infrared excess at 3-30 um wavelengths https://www.aanda.org/articles/aa/pdf/2017/07/aa30582-17.pdf
Although this simply suggests some circumstellar dust, I wonder whether the low visible luminosity and IR excess might also fit a model of a partial Dyson swarm around this star?
I’m very interested in Greg’s remarks and wonder if he would comment on the possibility that the transmissions are coming from a satellite in orbit around Proxima b or c? To keep it simple, what altitude would the satellite need to be in to give the positive drift with the know positions and movement of these two planets? The other possibility is something associated with a possible rings around Proxima c or the supposed dust cloud just outside the orbit of c. These could all be artificial tecnosignatures structures from these locations and Proxima Centauri is one of the few places we have enough details about the structure of the system to understand where and what may be sending a signal. Hopefully the two articles that should be coming out soon that may hold information on changes in the drift rates that could pin down the movement over time.
I should have added that, for them determining our time units was the tricky part.
.982 being close pi squared adds some credence. Some have though it might be a natural choice, cf. http://articles.adsabs.harvard.edu//full/1995ASPC…74..267B/0000270.000.html.
Dave
Thanks for the post. I noticed the NYT article on New Year’s eve, which led to some googling which brought me here.
The radial orbital acceleration of Proxima b is ~(47km/s)^2/0.0485AU ~ 30 cm/s^2. This is about 30x larger than the centripetal acceleration at Parke’s 30deg S location, 50x larger than Earth’s orbital acceleration, and ~300x larger than the centripetal acceleration of Proxima b’s equator with respect to the planet’s spin axis. So on a 3h time scale, the drift is determined by the location of Proxima b in its orbit.
April 29 2019, Noon UTC = JD 2458603. Using the new Proxima b fit from the ESPRESSO confirmation, the planet was about 30 degrees past its inferior conjunction at that moment. So the planet was accelerating *away* from Earth at ~25 cm/s^2 when the observations were made, which is inconsistent with the positive drift.
Now of course there’s always Proxima c…
Michael Fidler’s idea of an “Atmospheric Lens” is interesting.
Okay, if the signal is not a hoax and appears to be from Proxima, then – as Jason correctly remind us – it was emitted 4 years ago; and it lasted for 3 hours.
Now, it is always fun to do some numerology and some very Wild Wild West speculation. By now, one should know that not Pi (3.14) but Tau (6.28) is what an intelligent lifeform will use to demonstrate their intelligence. 982 screams a little bit for 628. 982-628 = 354; interesting (dimensional wise).
Thus, we put this “982 628 354” in Google to solve the differential equation (sic) and we get this: https://www.lens.org/lens/patent/158-982-354-628-774 which is like a Jodie Foster system and method for coordinated data transmission.
I admit, it’s New Year’s Eve, wine on top of 2020 may cause quite some blur in my vision.
The example figure shows a signal from Voyager II. This gave me the idea that BLC1 might be broadcast from a space probe launched towards us from the vicinity of Proxima b. Would that account for the blue shift? Are the other characteristics of BLC1 consistent with those of a space probe?
This cannot be ruled out, AFAIK. We can’t even be sure it’s not coming from Earth orbit!
As there is no distance information collected at the moment, how do they rule out it is coming from the direction of the proxima system, but from a much more distant source, just by accident?
Thanks for the link.
I wonder, why the Breakthrough Listen even considers other galaxies as potential signal sources, given the enormous transmitter power that would be required for them to message us…
If we wanted to, we could build a kilometer-size dish or two, with accordingly upscaled transmitters… Even then, how far could we transmit, and be heard with a similarly-sized dish in another stellar system?!…
An Interstellar Relay Network seems to be the most (if not the only) wise solution; see for example J.A. Fraire et al., “Networking in Interstellar Dimensions: Communicating with TRAPPIST-1”, IEEE Transactions on Aerospace and Electronic Systems, 2018 https://www.researchgate.net/publication/328083392_Networking_in_Interstellar_Dimensions_Communicating_with_TRAPPIST-1 (see Figure 5 therein).
Indeed, 982.002 MHz is both very close to 3 times Deuterium rest frequency + 150 kHz as well as almost an exact integer of a MHz, so let us see…
982.002 = PBSOOS = proxima B SOS
just joking ;)
1. Typically many beamwidths. They know what they’re doing.
2. We don’t yet know the observing cadence or when the signal was present.
3. We don’t know the width, but if the signal passed their tests, it must have been very narrow, of order Hz.
4. No, I don’t think they said that the drift was consistent with Proxima b. My read of the articles is that the fact that it was drifting at all means it’s consistent with a non-terrestrial source, such as an exoplanet.
Re: 980 Mhz band usage
“The 960-1164 MHz band is part of the 960-1215 MHz band allocated on a primary basis to the Federal Government for the aeronautical radionavigation service (ARNS).”
” TACAN in general can be described as the military version of the VOR/DME system. It operates in the frequency band 960-1215 MHz.
I have a number of comments/questions:
1. How far is the dish moved when “nodding” to eliminate off-target noise?
Beam width for antennas is usually defined as twice the distance from center beam to the half power (gain) point. With a sensitive enough receiver, you may have to move the dish several “beam-widths” to ensure a noise signal falls below your sensitivity threshold.
2. How did the signal terminate? Did it fade, terminate abruptly during a 30-minute window, or was it just not present during the next 30 minute window? Is the dish “nodded” for the same amount of time it is on target? I read somewhere it was present for 5 thirty minute intervals over 30 hours. Were these consecutive intervals or interleaved with 30 minutes of “nodding”?
To me, a signal that terminates abruptly, and then repeats, is more indicative of an artificial signal whether it’s source is terrestrial or not.
3. I keep hearing the signal was narrowband. How narrowband? Narrower than we typically use for RF communications or just narrow compared to natural emitters?
4. I’ve also heard that the signal’s Doppler change with time is “consistent with” being sourced by Proxima Centauri b, but that it is changing in the wrong way. That planet has an 11 day orbit and unless we know exactly where it was in its orbit, the Doppler may be increasing or decreasing. Also, since it is only 1.2*M_e and orbiting about 8 times as close to its sun as Mercury is, it is probably tidally locked. Therefore, assuming Proxima b is tidally locked, the Doppler change due to its rotation (43.67 m/s) is negligible compared to that from its orbital velocity (47,390 m/s) than its rotation component. See math below.
————————————————————————————————————
Orbital velocity of Proxima Centauri b:
M_proxima = 0.1221 * M_sun = 0.1221 * (1.98e30) = 2.418e29 kg
r_p = 7.181e9 m
v_orbital = [G*M/r] ^ 0.5 = (6.67e-11 * 2.418e29)/7.181e9 ]^0.5 = 4.739e4 m/s
= 47,390 m/s
Assuming Proxima b has the same density as the earth:
M_b = 1.173 * M_earth
R_b = (1.173)^0.333 * R_earth = 1.055 * R_earth = 1.055 * (6.378e6) = 6.726e6 m
T_b = 11.2 days = 9.677e5 seconds
w_b = 2*pi * f = 2*pi/T = 2 * pi /(9.677e5) = 6.493e-6 rad/s
v_rotational = R_b * w_b = 6.726e6 * 6.493e-6 = 4.367e1 m/s = 43.67 m/s
In summary:
v_rotational = 43.67 m/s
v_orbital = 47,390 m/s
————————————————————————————————————
Yes:
https://arxiv.org/abs/1906.07391
Has anybody attempted to use an AI trained in pattern recognition in the search of candidate signals?
I don’t think we know if Proxima is in a spin-orbit resonance. That would require a slight orbital eccentricity, but I don’t think we can rule that out.
We don’t know the drift rate that was, and without a spin model for Proxima b we can’t say much about whether it was the potential source.
This is kind of two parts…
I seen the most popular belief is Proxima B is tidally locked. I also seen there is a possibility its in an elongated orbit allowing for a three day rotation per two orbits. Has this been worked out yet?
Now with signal being visible for three hours and adding in B’s movement is it likely the TX source had to track Earth?
What if a civilization is using the planets Proxima Centauri b or c as a “Atmospheric Lens” as in Prof. David Kipping “Terrascope”? This would give them the ability to observe earth closely and send and receive signals.
The “Terrascope”: On the Possibility of Using the Earth as an Atmospheric Lens.
https://arxiv.org/abs/1908.00490
Planetary Lensing: Enter the ‘Terrascope’.
https://www.centauri-dreams.org/2019/08/12/planetary-lensing-enter-the-terrascope/
These data were not taken as part of the normal BL data acquisition program, so they won’t be up right away. Presumably they’ll post them after the paper goes up.
But these are not “recordings” of the sort you might be able to listen to. If you are fluent in Python, you can use Blimpy, written by the BL team, to view and analyze the spectral data yourself:
https://github.com/UCBerkeleySETI/blimpy/blob/master/README.md
My read of the article is that it was present for around 3 hours, although they observed other days, as well, and it was no there then.
In principle, but I suspect they did not record polarization information.
Can anyone recommend software for viewing Breakthrough Listen Open Data Archive recordings? I did not find any recordings from the described period, but if they appeared…
How long was the signal tracked, 30 hours or 3 hours ?
What day and time in April/May 2019 ?
Would a modulation using polarization instead of amplitude/frequency be detectable by Parkes?
Would it make sense to search for a relayed signal from within our own solar system?
No, this is not the kind of signal you can listen to. It contains no information at all.
Proxima continues flaring can cause serious interference with radio frequencies. This would cause problems with transmissions of a beacon source and may only allow limited time when the ionosphere will let it pass thru.
“And note that this scheme does not assume that the message is meant for us—the Solar System may just be one stop in a network.”
So if this signal is then relayed to the next star, would we necessarily detect *that*? Would it make sense to look for relayed signals from within our own solar system?
It is interesting that the signal appears to come from our nearest star, as has been pointed out.
Just for fun, it’s amusing to think that the reason might be that they, or it, is headed for us.
Imagine crossing the country from New York to LA, stopping at gas stations along the way. Maybe they were just “topping off” with some deuterium and tritium for their fusion reactors at Proxima before completing the last leg of their journey.
Anyway, keep the lights on!
Or off, maybe?
Hi.
Is there a way for the puplic to listen to the signal? I am highly interested. Just out of curiosity.
Greetings from Germany
Hello!
Superb explanation that doesn’t get TOO scientific, and it’s not too “mainstreamy” either. Thanks!
(By the way, Smithsonian Mag started their article with “signal from a nearby galaxy” <– that is some major cringe there.
I liked your speculative remarks with the "cell phone tower" analogy and otherwise pointing out that YES INDEED, wouldn't Proxima make a lot of sense for such a signal?
PS. People speculating it could be terrestrial and from some type of transmitter, but doesn't the "shifting away" of the telescope and the signal disappearing strongly speak against that?
The team does not generally save baseband data; there’s just too much of it. In the future, they might be able to do real-time signal detection and save only the relevant baseband data for potential signals, but that is not something they currently do. I think that’s always been the plan, but it’s hard and they have a lot of other priorities.
yes ok raw RF data is probably too much to ask for. But maybe baseband data with 1MHz bandwidth around 982 MHz?
I checked the Breakthrough Listen website, but although there is very recent data available to download, the last data from Proxima seems to from 2017…
Its understandable of course that the team would like to finish their study first. So I guess we all just need to wait a few more weeks… damn :)
No, it’s unlikely that the raw voltages were saved. The 3-hour block of time in question probably adds up to around 10 TB!
But they will publish the dynamical spectra (power in the time frequency domain).
BTW, is there any way to access the raw ADC data from these observations?
I’d love to do some signal processing on it myself…
I don’t know because I haven’t seen the data.
What power levels/antenna gain would be needed at Proxima to produce the
signal strength seen at Parkes?
Correction:
Parkes radio telescope is a receiver only, what is the status of the 70m DSS-43 telescope at the Canberra Deep Space Communication Complex? Is it capable of monitoring Proxima Centauri at 982 MHz?
Found some updates for DSS-43; The antenna has been offline since early March 2020, and the upgrades are scheduled to be completed by January 2021.
https://www.nasa.gov/feature/jpl/nasas-deep-space-station-in-australia-is-getting-an-upgrade
No, 150kHz on 982MHz is around 45 km/s, which is much larger than the magnitude of the Earth’s motion.
If it has experienced significant Doppler shift, for whatever reason, that chances it would be shifted to a number so close to an integer are small. That’s the argument for it being not Doppler shifted and terrestrial.
No, we don’t know the signal strength yet.
I’m not sure SETI needs more marketing—from a journalism perspective it’s one of the most bankable topics around. There are probably more articles about SETI in the news than actual journal articles!
But I agree that these kinds of stories, done right, as they were here by SciAm and NatGeo, are good for the field.
That said, there’s no reason this had to happen now. We could have all had the same conversation when there was more to say.
My humble opinion is that the analysis of terrestrial, or man-made signal sources should not be limited to signal sources that are assumed to operate on 982MHz, but also those that operate on any integer division of that frequency. For example, a CW class C-amplifier , that operates on 492MHz and has poor antenna port filtering may emit on 982MHz. So when searching possible satellite candidate, should consider also the ones that operate on the sub-harmonic frequencies.
Thank you for giving some insight to this intersting case. Due to the very close to integer frequency it seems very likely to be earth bound. Small frequency drifts, e.g due to temperature variations are also very common.
“1) It’s always possible that the modulation is so subtle that you can’t detect it, but that’s a strange way to transmit information. Why not make it as obvious as possible?”
Well if you need to communicate over several light years, your link budget is so low the you need to user very low modulation frequencies. So its not suprising that these modulation will be hard to detect
Time to stop doing SETI with single dishes and employ long baseline interferometry….
One more thing…
Could the 150KHz discrepancy in Eric’s deuterium hypothesis be due to the redshifting effect of the Earth’s rotation? The hypothetical aliens wouldn’t necessarily know if the receiving antenna would be on or off Earth, and so might not bother trying to compensate for shift at our end.
This is a truly amazing post, Jason. Thanks so much!
A quick point and a naïve question:
I would think signal drift due to a spacecraft in a Molniya orbit, a transmitter on the surface of Proxima b (a tidally locked planet), etc could be modeled and compared to the actual drift. On Event Horizon you mentioned that you and some colleagues are doing some math on this…is that what you have in mind?
If we don’t know what kind of movement is causing the drift at a hypothetical transmitter near Proxima, I don’t understand how we can know the intended broadcast frequency. So, it seems to me, the original broadcast signal was either something else (and probably not an integer), or the broadcast was compensated so that we’d receive 982 MHz. If the latter, then it’s definitely intelligent in origin, and we should start thinking seriously about the Deuterium idea. Either way this integer issue isn’t a concern. Am I missing something? I probably am.
Found the article on Radio Leakage from Earth. The book, Life in the Universe has a chapter on this and was able to find a online source.
Eavesdropping Mode and Radio Leakage from Earth.
WOODRUFF T. SULLIVAN III
https://history.nasa.gov/CP-2156/ch5.4.htm
Another article on the subject with a good graph.
Are we screwing ourselves by transmitting radio signals into space?
https://io9.gizmodo.com/are-we-screwing-ourselves-by-transmitting-radio-signals-493800730
https://io9.gizmodo.com/are-we-screwing-ourselves-by-transmitting-radio-signals-493800730
Looks like the Parks radio telescope is the only large transmitting scope that can be seen by Proxima Centauri at 33 degrees south latitude. The northern hemisphere can not be seen by Proxima.
You might find this interesting.
Edward George Bowen
Born 14 January 1911
Died 12 August 1991 (aged 80)
Alma mater Swansea University
Scientific career
Fields Radar, Astronomy
Edward George “Taffy” Bowen, CBE, FRS (14 January 1911 – 12 August 1991)[1] was a Welsh physicist who made a major contribution to the development of radar, and so helped win both the Battle of Britain and the Battle of the Atlantic. He was also an early radio astronomer, playing a key role in the establishment of radioastronomy in Australia and the United States.
Tizard Mission
See also: Tizard Mission
Bowen went to the United States with the Tizard Mission in 1940 and helped to initiate tremendous advances in microwave radar as a weapon. Bowen visited US laboratories and told them about airborne radar and arranged demonstrations. He was able to take an early example of the cavity magnetron. With remarkable speed the US military set up a special laboratory, the MIT Radiation Laboratory for the development of centimetre-wave radar, and Bowen collaborated closely with them on their programme, writing the first draft specification for their first system. The first American experimental airborne 10 cm radar was tested, with Bowen on board, in March 1941, only seven months after the Tizard Mission had arrived.
The Tizard Mission was highly successful almost entirely because of the information provided by Bowen. It helped to establish the alliance between the United States and Britain over a year before the Americans entered the war. The success of collaboration in radar helped to set up channels of communication that would help in other transfers of technology to the United States such as jet engines and nuclear physics.
Australia
In the closing months of 1943, Bowen seemed to be at “loose ends” because his work in the US was virtually finished and the invasion of Europe by the Allies was imminent. Bowen was invited to come to Australia to join the CSIRO Radiophysics Laboratory, and in May 1946, he was appointed Chief of the Division of Radiophysics. Bowen addressed many audiences on the development of radar, its military uses and its potential peacetime applications to civil aviation, marine navigation and surveying.
In addition to developments in radar, Bowen also undertook two other research activities: the pulse method of acceleration of elementary particles; and air navigation resulted in the Distance Measuring Equipment (DME) that was ultimately adopted by many civil aircraft.
He also encouraged the new science of radioastronomy and brought about the construction of the 210 ft radio telescope at Parkes, New South Wales. During visits to the US, he met two of his influential contacts during the war, Dr. Vannevar Bush who had become the President of the Carnegie Corporation and Dr. Alfred Loomis who was also a Trustee of the Carnegie Corporation and of the Rockefeller Foundation. He persuaded them in 1954 to fund a large radio telescope in Australia with a grant of $250,000. Bowen in return helped to establish American radio astronomy by seconding Australians to the California Institute of Technology.
Bowen played a key role in the design of the radio telescope at Parkes. At its inauguration in October 1961, he remarked, “…the search for truth is one of the noblest aims of mankind and there is nothing which adds to the glory of the human race or lends it such dignity as the urge to bring the vast complexity of the Universe within the range of human understanding.”
The Parkes Telescope proved timely for the US space program and tracked many space probes, including the Apollo missions.
Fascinating discussion.
Any information on the received power of the transmission? That would allow an estimate of the transmitter power (assuming the transmitter is in the Proxima system).
If this is part of a galactic communications system, then you’d expect a similar transmitter to exist in our solar system. However, I somehow doubt that we would have missed a transmitter of that power in our own solar system. I expect many radio astronomers are spending their Christmas break poring through old datasets looking for a 982.002 MHz signal.
Thank you for this post Jason. It’s noble that the SETI community follows strict protocols for determining whether we have a real ETI signal, and also for reporting candidates to the media. However, at this point, we all get that caveats and the ‘maybes’ around candidate signals. We need more of the ‘what if it were’ posts like these: they’re undeniably interesting and generate significant media buzz. It’s called marketing, and SETI needs more of it. The buzz right now is only good and can only be good, even if this turns out to be another microwaved lunch. Love the post, and love your passion and enthusiasm. We need more scientists to break from their malthusian dogma to the method and explore their passion like you do. You are the reason, nearly single handedly, that SETI is increasing in interest over the past 7 years or so. Enjoy your holidays sir.
Just for the record, Proxima b is in an 11.18 day orbit with a semimajor axis of 0.0485 AU, and the orbital phase is known from radial velocity measurements. That means the mean orbital velocity is 47.19 km/sec and mean orbital acceleration is 0.307 m/s^2. If it rotates once per Earth day (it should be orbitally locked, but just assume) its rotational acceleration is ~ 0.0362 m/s^2, so _the orbital Doppler shifts should dominate the rotational ones_.
The maximum orbital Doppler shift at 982 MHz is thus ~ 1 Hz / s. It is just possible that a severe ionosphere effect could match that – someone should look at the TEC from the IGS GPS receiver at Parkes. I don’t know how that compares with what they are seeing.
Great article.
This analysis might be of interest:
The issue is that the frequency is suspiciously close to an exact integer number of MHz, which seems unlikely to be unintentional.
There have been several assertions here to the effect that measuring frequency in Hz is a human construct, not necessarily shared by aliens. Well, how else is one to measure frequency except in cycles per unit of time? What we call one second is obviously arbitrary, but not so with regard to electromagnetic oscillations. The idea of the frequency being 3x deuterium is truly fascinating.
No, the telescope would not have been pointed that low while observing Proxima.
In regards to the integer based MHz. It’s possible our future friends at Proxima have observed our broadcasts and are using the same MHz standard to reply. Isn’t that what we would do?
Also, I’m fascinated with the perceived lack of modulation. Makes me wonder if it’s just our naive views or lack of technology to properly investigate it.
What would be the most powerful frequency of our Earth’s electromagnetic spectrum as seen from Proxima?
If the telescope was nodded and there was only detection when pointed towards Proxima, that would surely rule out an Earth based source. Also if the detection stretched over a long time, any satellite would drift out of the line of sight ( probably but any spy satellite could move in ways we wouldn’t know). If this is the case, a human made source is almost eliminated.
Thanks for this write up. I sure do hope this thing repeats!
Re the suspiciousness of it being an integer value of hertz: perhaps they’ve been able to deduce the standards we use by watching the emissions coming off our planet? Assuming it actually is ET, that their intent was to get our attention, and that their technological capabilities are a few decades more advanced than ours, it makes sense that they would try to do so using “our” system. A seemingly random value would be more likely to be dismissed as random.
Could it be that the signal came from a drone in the area around the telescope? If the signal was quite close to the horizon it might be a remote controlled drone from the surrounding towns or villages. Those drones are operating at a frequency above 900 MHz. It could be that the drone was hovering at a spot in the same position for 3 hours or it had a pre progammed flight path that would make it look like the “displacement” seen. Not sure how long a drone battery lasts, but it could be an explanation that came to my mind. So more like a microwave oven event. Not that I am hoping that it is Vulcans…
Just a Guy – if a transmitter is located on, say, a planet’s equator, you can only see it for half the planet’s rotation. You first see it as it rotates around from the back of the planet and it is coming directly towards you – maximum blue shift. Then the blue shift reduces until it has rotated 90 degrees and is moving sideways relative to us for a shift of zero and then it starts red-shifting as it begins to rotate away from you for another 90 degrees, at which point it is again blocked by the planet. So the frequency is dropping for the entire 180-degree rotation.
Proxima is about 4 light years away so any signal sent to us was sent 4 years ago.
if the source was proxima centuri, how long would it take the radio waves to get here? the signal must have been sent a long time ago? probably from long before we had radio communications? and how strong would the radio signal need to be, in eirp?
The difference between detected frequency and 3x Deterium corresponds to ~45 km/s doppler redshift. In turn, velocity of Proxima Centuri is about 22 km/s respect to Sun. This coincidence may deserve further attention.
Based on that link it look like it would have to be a different beacon—the Parkes teams seems well aware of that RFI, and it’s not at 982 MHz.
I don’t follow. Is 982 MHz 21X or 91X?
I also followed the pilotnav.com link and I don’t see any airports transmitting anything at 982 MHz or on 21X. Is there something on that site that suggested otherwise to you?
I don’t know the time resolution of these data, but they would probably not notice modulation in something pulsed any faster than a few Hz.
If this is something airports do, it’s unclear to me why it would be intermittent, and not a well known feature of the Parkes telescope, unless the airport is sparsely used. It’s also unclear why it would be chirped. But maybe worth thinking about!
Seems I slipped a bit,,,the DME channel corresponding to 982 MHz is 21X not 91X.
also found this
https://www.parkes.atnf.csiro.au/observing/rfi/parkes_rfi_studies/airport_beacon.html
Mark
WB2WHC
982 MHz is in the aeronautical navigation band and specifically is a ground station frequency for DME and the nomenclature is CHANNEL 21X.
There are some airports in Australia assigned to this channel
https://www.casa.gov.au/sites/default/files/distance-measuring-equipment.pdf
Look at this list for the airports assigned to channel 91X = 982 MHz
https://www.pilotnav.com/browse/Navaids/continent/Oceania/country/AUSTRALIA/p/2
Normally a DME station will not be transmitting a steady CW tone. This could be related to a malfunction or testing?
Mark
WB2WHC
That’s interesting about it being 3 x deuterium! Presumably a coincidence, but when we know more about the observations we could check to see how close it really is. As-is, the signal is off of that factor by about 150 kHz, which isn’t all *that* close considering the number of possible “interesting” frequencies there are.
The signal data should be submitted to “No Such Agency” and its equivalents in Russia, China, etc. requesting a collaborative analytic effort by these super-spooks to uncover any evidence of information carried. If successful, even if undecipherable as to meaning, it would be a Grand Resetting of Fermi’s Paradox and. humanity’s world-view, and a few return tickets to Stockholm.
Contrary to Dartnell’s proposal, I think it is even more likely to find (or being found by) someone near than far away. For the same reason the neighbour just above gets on someone’s nevers, instead the one living three levels away.
Also what would be the best way to get someone’s attention? A narrow-band signal, shifting in a contra predicted manner wouldn’t be the worst choice.
The beauty of it — if it is actually E.T. — we would be able to communicate forth and back within a lifetime.
Since Hz is an arbitrary human-based unit of time, and the signal is so close to being an integer, I see this as being only one of two things. Either as a stray Human signal, or a reply from intelligent life from another world. If this isn’t noise, it should be treated as a reply to something we are sending.
Good summary of where this is at. One thing I’ve noticed (and apologies if this is incredibly ignorant, doing the best I can with no education in the subject)
982.002 is almost exactly 3x 327.384MHz, which is the rest frequency of deuterium (https://www.craf.eu/iau-list-of-important-spectral-lines/). 3 times, 3 stars? Also, deuterium an the Alpha Centauri system have a little in common: 2 stars like a proton & neutron in the middle, with Proxima far out, like an electron. So why not bring attention to deterium? But then again, why not just broadcast on the 327.384 frequency? But since it seems its not modulated, this would be a very quick way to communicate it is of intelligent origin without wasting any other attempts at trying to send data that may never be understood. On the other hand, it may just be a more “scientific” sounding bit of numerology on my part. Ah well. :-)
Ok I’ll go back to my speculative fiction stories now.
It’s negative for the transmitter’s planet for the same reason it’s negative for the receiver’s planet: if you are on the same side of your planet as the other telescope, then when the other one rises over the horizon you’re moving towards it at maximum blueshift. By the time it sets you’re at maximum redshift.
The only exception is if you are near your planet’s pole and the other telescope’s star is close to your celestial pole. For instance, consider a circumpolar star. You can observe it all day long, so you get the full sinusoid of its Doppler shifts over a full day, including the positively sloped side.
1) It’s always possible that the modulation is so subtle that you can’t detect it, but that’s a strange way to transmit information. Why not make it as obvious as possible?
2) Yes, if the drift is from an acceleration and not inherent modulation, it must be accelerating as least as much as Parkes was in that direction. Yes, the acceleration due to Proxima b’s orbit is much larger than that.
I would guess the UWL ultrawideband receiver based on the frequency and the science and the fact that they were nodding.
Thanks for this very fast writeup! I have two questions:
Do we know which receiver at Parkes observed the signal?
&
When the Boyajian’s Star light-curve data became available there were a lot of attempts to replicate the curves via simulation. Is such a thing possible to help look for the nature of the transmitter?
Thank you for this very interesting and detailed summary. The “cell tower” analogy was new to me and is an interesting hypothesis for SETI generally.
I do wonder if you might be able to weigh in on a couple questions I had:
-Could there have been modulation that was simply not detectable/smeared out by the Parkes telescope? Human-made RFI would have modulation, too, wouldn’t it?
-Since the drift rate was apparently enough to overcome the negative drift rate of the Earth’s rotation, such that we detected a postive drift rate, does this imply that the source is moving “faster” than the speed at which the Earth rotates? (Admittedly comprehending this is not my strong suit.) Is that a realistic speed for Proxima b’s orbit, or even any orbit of a moon, or of some sort of hypothetical artificial communications platform?
If BLC1 ends up as a “maybe” that we have to wonder about, I hope there will be a lot more checking back in the future looking at Proxima Centauri to see if it can be found again. Since the SKA will apparently be sensitive enough to be able to detect unintentional radio “leakage” of the sort our civilization gives off all the time, I also think checking nearby stars for that sort of excess, especially Proxima, should be done at the first opportunity (even before SKA is finished if possible). Of course, we don’t know if an alien civilization would use radio amongst themselves like we do anyway, but it’s certainly worth a look.
Thanks for this interesting article. But I don’t understand what’s the problem with the positive drift. You say: “It also can’t be from the rotation of a planet that hosts the transmitter—those shifts would also be negative”. Why we should observe positive and negative drift? That’s depend on the observation time, and the time for the planet to complete a rotation, no? Where I have wrong?