Category Archives: SETI

If we ever talk to Alpha Centauri…

There’s a star system near our sun; it’s distance from us is only 4 light years and change. This Alpha Centauri system (AC) has long fascinated science fiction visionaries, since its close distance makes interstellar travel a little easier to imagine.

But consider this: while we are not even close to being able to send a probe to AC at even a fraction of the speed of light, we can, today, send radio messages to this nearby system, with a chance of it being detected within a human lifetime.

Let’s review what kind of system that might be over there. The AC system consists of two stars, both are approximate analogs to our sun. Assuming that it’s possible for planets to have formed around these stars (this would require both stars to have formed at a greater distance apart, then moved closer together), there would then be two habitable zones.

Imagine a habitable planet around each star, or better yet, TWO habitable (and inhabited) planets around Alpha Centauri A, with another around Alpha Centauri B.

Suppose our Venus was not only habitable, but also possibly inhabited. Wouldn’t our space exploration experiences be a little different today? Would our civilization be different? And our attitude toward space exploration?

Inhabitants of one of the planets around Alpha Centauri A would, after exploring and perhaps colonizing, and certainly learning from their Venus, would be prepared to explore Alpha Centauri B’s planet, and possibly then Proxima Centauri.

What I am saying is, that it’s very possible that our nearest star system could be an ideal place to search. The civilization there would not have to be much more advanced than our own, but due to their environment and experiences, they could have a rich set of data for us.

Unfortunately, AC cannot be seen by those of us north of the equator, at about -60 degrees of declination. And more to the point, many scientists are wary about deliberately sending out a message into space, imagining that ET would look like Darth Vader and seek our solar system for reasons that would not benefit humanity.

Keep in mind, however, that faster-than-light travel may be completely impossible, that even a practical sub-light trip to AC would take more resources than any responsible civilization would commit (involving cannibalization of their home star). Further, we may safely presume that any interstellar civilization capable of coming to our star system and wreaking havoc, probably knows about us already.

That said, there is a new radio-telesope array being prepared, south of the equator, that will be capable of detecting radio signals from the AC system. This is the Square-Kilometre Array or SKA (

The SKA will be capable of detecting extremely weak extraterrestrial signals if existing, and may even detect planets capable of supporting life. Astrobiologists will use the SKA to search for amino acids by identifying spectral lines at specific frequencies. SKA will be able to detect an airport radar within 50 light years.

One of the candidate radiotelescopes in this array is located in Murchison, Australia, close to where the legendary Murchison meteorite was found. Perhaps that is a harbinger for this project’s future success.


Aliens will be here next year, and they will want our beer

Altair is a bright star in the contellation of Aquila. It is only 16.7 light years away. We don’t yet know if there are Earth-sized planets on Altair, but we have just begun to learn how to look.

Nishi-Harima Astronomical Observatory

Here’s the problem: In 1983, Hisashi Hirabayashi and Masaki Morimoto were two astronomers at the Nishi-Harima Astronomical Observatory…

Well, this is awkward. It seems that they had enjoyed a little something to drink.

NOT one of our esteemed scientists…

And they sent out a message in the direction of Altair.

“KANPAI!” Was the message, a traditional Japanese toast. They also sent the details of an alcohol molecule.


This was not the first message that Earthers have sent in the direction of the stars. The famous Arecibo message was sent in 1974, for instance.

But what’s interesting, and a little concerning, is that the signal to Altair will have already arrived by now (ca 1999), and if any Altairians received this message, and if they decided to reply right away, we will receive their message (or their light-speed invasion ships) sometime in 2015.


Tracking a starship

If we look at the Drake Equation and ponder the Fermi Paradox, we should expect that, out there in the blackness, there must be advanced civilizations, with hopes, dream, aspirations – and questions – similar to our own.

Of course we wonder whether they are trying to signal us. But what if they echo one of our fondest dreams? To travel to the stars!

When our best scientists imagine ways to get to the nearest star, they get a plethora of technologies worth looking at, and most of them use enormous amounts of energy. This is bad news for us, if we dream of putting something like this together.

But the good thing about this consumption of energy, it guarantees some kind of unmistakable signature. An alien starship zipping from system to system would stand a very good chance of being detectable.

Detection of Extraterrestrial Civilizations via the Spectral Signature of Advanced Interstellar Spacecraft, by Dr. Robert Zubrin

A digest version: To Detect a Starship

For the goal of traveling to the nearest star, many spacecraft propulsion systems have been proposed. The systems that appear to be capable of producing the most thrust, require the use of antimatter.

When anti-matter meets matter, it’s expected that this releases colossal amounts of energy, which can be harnessed as thrust. Awesome as this might be, most estimates place the velocity available as somewhere around 10% of the speed of light.

Some think that positrons can be substituted for anti-matter, with a similar production of thrust.

Not surprisingly, a huge amount of ink has been spilt regarding this largely theoretical technology:

New and improved antimatter spaceship for Mars missions

Antimatter propulsion – the beginnings of true interstellar flight

Re-thinking the antimatter rocket

Matter–antimatter gigaelectron volt gamma ray laser rocket propulsion

Fear not, I am not interested in developing a starship engine, or even exploring the possibilities past a point. All we need to know is that the leading candidate for interstellar propulsion, would involve antimatter or positrons, and would inevitably emit HUGE amounts of gamma-rays in the opposite direction.

Gamma Rays!

Even fusion rockets, fission rockets and magsails, in fact almost any effective propulsion system, seems to emit lots of gamma radiation. Zubrin and others have even visualized and calculated how large a starship would have to be in order to make this worthwhile. To my mind, this is interesting, but not necessary, since we are not building the thing – we are just watching the skies.

Certainly other technologies are being considered, including solar sails, wormholes, Bussard ramjet, Alcubierre drive or whatever. But among millions and millions of spacefaring civilizations, some are bound to try antimatter propulsion.

Such an gamma-ray signature would be a much higher-powered extraterrestrial signal, much easier for us to see than a directed or incidental radio signal.

So my suggestion is that we should just look for gamma-ray emissions out there in the blackness. And don’t be surprised that astronomers are familiar with a number of different types of gamma-ray sources in the universe.

Gamma-ray bursts

I don’t have all of the answers to this, of course. But going from a model of “assume no ETs” to a model of “they could be out there”, then we need to consider whether we are looking at exhaust from an ET’s engine today. Are there characteristics we need to be looking for that would suggest an artificial origin?

A gamma-ray burst can last from milliseconds to several minutes. The theories for the source of these events? The bursts that are longer than a few seconds? A supernova, a hypernova or a magnetar.

The shorter ones, from milliseconds to a couple of seconds? That’s unknown! They are not usually near any obvious stellar source, such as supernovas. Possibly from the merger of binary neutron stars?

The energy emitted is at a very narrow angle, and at a speed nearly at the speed of light. Unless the gamma rays are emitted as two equal and opposite jets, then the source would be impelled at a very high rate of speed. And if that’s true, then we would see a red-shifted signal – and we do occasionally!

The source for a short gamma-ray burst, whatever it is, must be a relatively small object, based on these observations. Possibly a mothership built to sustain large numbers of travelers for many years.

Once we get a candidate signal, Zubrin, in his paper, suggests using this data to calculate the putative starship’s trajectory: where it came from and where it’s going.

Our astronomers may actually be looking down the tailpipe of an interstellar craft right now, without knowing it. Realizing that could be truly history-making.


If there are indeed extraterrestrial civilizations (ETC) out there somewhere, then evidence of their existence may be visible to more than just somebody on their back porch watching a strange light in the sky. Chances are that astronomers are looking at artifacts from ETCs right now, and like a skeptic trying to explain away a UFO sighting, they could be grasping any explanation that did not involve ETCs.

Recently I just started glancing through Wikipedia, looking at various types of unusual stellar activity, observing how astronomers categorized them, and attempted to explain them.

Found this:

After the initial discovery of pulsars, “At this point, Burnell notes of herself and Hewish that “we did not really believe that we had picked up signals from another civilization, but obviously the idea had crossed our minds and we had no proof that it was an entirely natural radio emission. It is an interesting problem—if one thinks one may have detected life elsewhere in the universe, how does one announce the results responsibly?” Even so, they nicknamed the signal LGM-1, for “little green men” (a playful name for intelligent beings of extraterrestrial origin). It was not until a second pulsating source was discovered in a different part of the sky that the “LGM hypothesis” was entirely abandoned.”

It seemed somewhat un-scientific to assume that it was not “LGM” just because there was more than one. I must have missed some major fact.

Then I found a transcript of a talk by Dr. Burnell, one of the discovers of pulsars.

“So were these pulsations man-made, but made by man from another civilization? If this were the case then the pulses should show Doppler shifts as the little green men on their planet orbited their sun.

This is not looking good. Do you see them making assumptions about the nature of ETCs? Paraphrasing: “Since the source was not in orbit around a host star, then this could not have been the product of an extraterrestrial civilization”!!!

Consider the possibility that the source was not in orbit around a star. Perhaps it emanated and was fueled by the star itself?


“The pulsar story clearly shows that phenomena which at first closely resemble expected manifestations of ETI may nevertheless turn out to be natural objects – although of a very bizarre sort. But even here there are interesting unexamined possibilities. Has anyone examined systematically the sequencing of pulsar amplitude and polarization nulls? One would need only a very small movable shield above a pulsar surface to modulate emission to Earth. This seems much easier than generating an entire pulsar for communications.

“For signaling at night it is easier to wave a blanket in front of an existing fire than to start and douse a set of fires in a pattern which communicates a desired message.”

-Carl Sagan

Let’s humor the dear departed Dr. Sagan and pretend that pulsars are indeed artificial beacons.

The Kardashev scale was developed by Dr. Nicolai Kardashev. It’s more of a thought experiment than anything, as far as mainstream science.

It classifies civilizations (earthbound and extraterrestrial) into three types, based on how a civilization uses resources. We are, of course, technically a Type I civilization. A type II civilization is a “civilization capable of utilizing and channeling the entire radiation output of its star”.

My point is, why should we be surprised if an advanced civilization harnesses a nearby star and makes it into a beacon? By the way, we have found planets orbiting around millisecond pulsars. That’s right, a millisecond pulsar (MSP). The first one discovered, PSR B1937+21 pulses at 1.557708 milliseconds, roughly 641 times a second. I wonder if a natural body can really rotate that quickly?
But what evidence do we have that might suggest that pulsars are placed by ETCs? Let’s look at that. There’s some interesting discussion on this site:

“We have often noticed that perfectly-competent scientists lose their capacity for rational thinking when it comes to the subject of ETI actually encountered, as opposed to ETI theoretically considered. In this, scientists reveal their common humanity, and this human race has a deep fear of such an encounter.”

What kind of utility would a pulsar have? Why would an ETC go through the trouble? Modern earthbound scientists find a large number of uses for pulsars, to start with:

The pulsar mentioned above, for instance has an extremely constant period at 3.3 x 10-12 sec/yr (better than our best atomic clocks).
Dr Paul LaViolette, speaks of the haste that science has taken to explain away pulsar behavior, and he notices some patterns in their distribution in our galaxy. Interesting reading.

Anyway, at this point, these are questions that I asking; I can’t make any conclusions at this time. But it’s interesting to wonder what else is out there that we are ignoring.

Radio source SHGb02+14a

This extraterrestrial radio signal was received in 2003 by SETI@home. It was detected three times. Its frequency was on or about the favored frequency of 1420 MHz.

BUT, it was not near a star (the nearest one was about 1000 light years out). The signal also had a lot of signal drift (likely due to some kind of Doppler shift).

One scientist remarks, “if [the aliens] are so smart, they’ll adjust their signal for their planet’s motion.”

But if that drift is due to a planet’s rotation, then the planet would be rotating at 40 times the rate of our Earth.

Do you see the assumptions that are being made here?

– Our alien friends would only be able to adjust their signal for their planet’s motion, if they were interested in transmitting in a specific direction; otherwise there’s no reason to adjust. And the signal drift may be part of the message: they have a fast orbit.

– However there is no star, and therefore no planet to cause any drift. How do we know that that equals “no aliens”? If they are voyaging from one star to another, then of course the signal will not be near any star.

– So the drift may be from some other movement of the source. Starship? Maybe. SETI doesn’t seem to have an alternative explanation prepared. Food for thought.


Wow, indeed.

The famous “Wow!” signal was detected by Jerry Ehman in 1977. It was a very strong, narrowband (10-kHz wide) signal that lasted as long as his Big Ear (and our planet) was pointed in its direction. It was in the hydrogen “waterhole” band of 1420 MHz (or precisely 1420.40575177 MHz). In fact, the two estimates of the frequency bracket the waterhole frequency perfectly.

Why was this not declared proof of alien intelligence in space?

  • It wasn’t located precisely on a star.
  • It wasn’t repeated. The signal was only received once.

What did we do? We sent the Arecibo message.