If it's not aliens, what are those signals?

… "And the third possibility is that it is aliens." Only the *third* possibility, mind. That's the assessment of Dr Seth Shostak, a senior astronomer at the SETI Institute (the Search for ExtraTerrestrial Life) in California. So what's all this speculation about aliens sending us signals from a faint star in our "neighborhood"? 

"On the basis of history, I would say the chances are not very great that it's aliens," Shostak told Deutsche Welle on Tuesday. "We go through this fairly frequently whenever anybody picks up an interesting signal - or anything unusual in the sky - and if you don't know what it is, one possibility is that it's aliens. Right? Well, look at history …"

In the 1960s, recalls Shostak, the British found a pulsing source of radio signals in the sky, and for a while they called them "LGMs," Little Green Men. But it turned out they were pulsars, a rapidly spinning neutron star, the remains of a more massive star. They look like a light blinking, not an alien winking.

"It's totally natural," says Shostak. 

So what could explain the radio signals that appear to be coming from the red dwarf star, Ross 128? Are they natural events like pulsars? Here's what we know so far.

Astronomers at the Arecibo Observatory say they picked up "peculiar signals" from Ross 128, a star just 11 light years from Earth, on May 13 of this year. In a blog post, Professor Abel Mendez, the director of the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo, describes the signals in more detail: "[They] consisted of broadband quasi-periodic non-polarized pulses with very strong dispersion-like features."

If you could hear them, which you can't really, they might sound a bit like sweeping, whistling sound, a modulating up and down. It's not the kind of signal alien hunters like Shostak look for as a rule.

"We generally look for narrow-band signals," says Shostak. "They are at one spot on the radio dial, like Norddeutsche Rundfunk - it's one spot you know where to tune to, because those are the kind of signals that are made by transmitters."

The SETI Institute has been helping the scientists at Arecibo collect data, with colleagues at the Berkeley SETI Research Center and SETI's Allen Telescope Array at Hat Creek, California. They hope to come to some conclusion by the end of this week. 

 

The signals from Ross 128, continues Shostak, "cover megahertz of spectrum, and the most interesting thing is that they seem to shift in frequency with time …" Then he makes that whistling sound, "going down the dial." 

"Each of the possible explanations has their own problems," writes Mendez in his blog, including the "recurrent aliens hypothesis." Yet speculation abounds. 

Help! My world is on fire!

There's something we should bear in mind here. Ross 128 is a star. It is not a planet. 

"There is probably no habitable life on that star. It is very hot," writes David M. Jacobs of the International Center for Abduction Research in an email to DW. "But I am not an astronomer, so be careful with what I say."

Thanks for the heads up.

Well, Jacobs may not be an astronomer (he's a retired professor of history from Temple University), but he's probably right, at least by my earthly logic, that stars are very hot places. Some red dwarf stars are known to have planets orbiting them - and those planets could hold life, perhaps a kind that's as sensitive to heat as humans, and if so, you'd hope for their sake their world was far enough away from their star. 

So could the signals originate from a planet around Ross 128?

"If there are planets surrounding Ross 128 and these are actual "signals," the technological level of the aliens would have to be very close to our level," writes Jacobs. They would be using the similar systems as we do, sending out radio "signals" for whatever reason. "If that is the case, [their] technology [would be] as primitive as ours." 

The problem is, warns Jacobs: "With the UFO and abduction phenomenon, people report extremely advanced alien technology of which they know nothing. UFOs do not send out signals of any type that we can find."

… Erm, right. Okay. Noted. 

Doubt upon doubt

Some scientists prefer to think our technology is pretty advanced, actually, certainly in the context of our overall evolution.

"Look, life developed on Earth about 3.5 billion years ago. And it's only been in the last 100 years, give or take a few, that we've been able to send radio waves into space. That's a very short moment," says Dr Martin Kürster at the Max Planck Institute for Astronomy.

That short moment, says Kürster, would have to "coincide with the same short moment of another civilization," and that's unlikely.

"The chance of having an advanced civilization capable of producing radio signals that nearby, only 11 light years away, is very, very small. If there is other advanced life in the universe, I doubt it's even in our galaxy."

And there's another problem - two other problems in fact: first, Kürster says no planets have been detected around Ross 128. That doesn't mean they don't exist, but we haven't spotted them, and we may not be able to tell them apart from the star.

"If the signals are from an alien life form, which I personally don't believe," says Kürster, "it would probably come from around the star. But the planet as seen from us would be so near to the star, the angle between the star and the planet would be so small, that we wouldn't be able to easily say that it's coming from the star or the planet. Because we'd basically be looking in the same direction."

What about other natural phenomena?

So, okay, it's probably not aliens - they would either be too advanced or too dumb to talk to us. Then what about stellar flares, or a burst from a high orbit Earth satellite? Both are potential explanations.

"Ross 128 is a small star. Our sun is 3000 times brighter, so Ross 128 is a small star," says Shostak. "But small stars are like small dogs - they tend to be very energetic, so they often do produce flares, and those flares may make some natural radio radiation, and perhaps that's what this is. It doesn't seem to be, but it's a possibility."  

Or it's terrestrial interference from a satellite. There orbiting Earth and they all tend to carry transmitters. But Kürster doubts that. He says "it would be difficult to reproduce the signal, because it requires a chance alignment of the satellite and our view of the star."

 

That being said, wouldn't it freak you out if they were signals sent by aliens?

"I don't know about freak me out," laughs Shostak, "there are other things that freak me out more, like a new scratch on my car. But obviously I must think they're out there, otherwise I wouldn't do this job. We're in Silicon Valley. You could walk across the street and double your salary, so if you're doing this job, it's because you think there's some chance of success." 

But still … what if? 

"This is one of the 12 closest stars. So if it turned out there was intelligence able to build a radio transmitter only 11 light years away, you'd have to say, 'Man, that's either incredibly lucky,' so lucky that I wouldn't believe it," says Shostak, "or there are intelligent critters everywhere!"