Mystery SETI Signal Set Rules of Engagement

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In the Fall of 1967, a small team of radio astronomers came face-to-face with a profound mystery that they didn’t want to be true.

At one point they half-seriously thought about destroying the data and staying stone silent. That’s because announcing it to the world could open a Pandora’s box for science, and derail at least one astronomer’s PhD thesis.

A small group of radio astronomers in the United Kingdom had stumbled upon clock-precision radio pulses coming from deep space. The signal was unlike anything ever seen before or even predicted in astronomy. In the absence of a natural explanation, the researchers pondered, for three long weeks, whether this was really a “hello” from an extraterrestrial civilization.

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The team faced a cultural black hole with regard to the public response. How do you verify the signal? How do you announce it to the world? Do you send a reply to the stars, or is that too dangerous?

As is the case in our compulsive universe, nature was cleverer than imagined. This story of mistaken identity, as recently researched by Alan Penny of the University of St. Andrews, set the stage for preparing a SETI protocol for how to announce the discovery of the real deal sometime in the future.

Little Green Men

In July 1967, a novel long-wavelength radio telescope, the largest of its time, began operations at the Mullard Radio Astronomy Observatory in Lord’s Bridge, Cambridgeshire, U.K.

Antony Hewish built the array to study radio emissions from quasars, a very distant, energetic and utterly mysterious newly discovered class of object (today we know they are the black hole powered cores of active galaxies). Graduate student Jocelyn Bell took home a 98-foot long paper strip chart of the telescope’s observations (this was a time before microcomputers and wide use of digital data processing and storage by astronomers).

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While marking up the chart in her attic, she noticed a peculiar source that was flickering like a police car strobe light. As any good scientist would do, she checked for instrument noise, malfunction or man made clutter. (In 1963 the all-sky glow of the cosmic microwave background was first suspected to be radio contamination from pigeon droppings in a radio communications antenna.)

Bell realized that the source moved with the Earth’s rotation. The source really is in the sky and somewhere out there in the galaxy!

The telescope’s builder, Hewish, was intrigued and installed a faster strip recorder. The ghostly source reappeared in On Nov. 28 and the astronomers recorded pulses that lasted a fraction of a second but recurred precisely every 1.3 seconds. The eye-opener was that the pulses were so short in duration that they had be coming from something smaller than a few thousand miles across. This might place the source on an Earth-sized planet rather than a star!

What’s more, the unusually narrow frequency of the signal mimicked the signature of man made radar transmissions.

In the absence of a physical explanation, the astronomers toyed with the possibility that the signal could be coming from an alien civilization.

The planet hypothesis was easily testable. If the source was orbiting a star, the signals should show a rhythmic frequency shift as the planet approached and then receded from us along a racetrack orbit. This is the high water mark in the team’s taking the E.T. hypothesis seriously. As far back as September, the phenomenon was nicknamed LGM for Little Green Men (just as spurious mechanical malfunctions are dismissed as “gremlins”).

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What if a planet’s motion was detected? Should the British government be alerted to hold a press conference announcing something so momentous as an “hello” from space aliens? Or should the data be trashed in favor of protecting Earth from being tempted to talk to E.T.? What if a hostile, invading civilization was “fishing” across interstellar space for a response to their beacon?

By the end of December, the LGM hypothesis quickly evaporated after astronomers learned the source is not orbiting anything.

The final nail in the coffin came when a second, and then a third pulsating source was found in December. It is very improbable that civilizations at three different stars widely separated in space and time should be simultaneously targeting us at exactly the same radio frequencies.

Finally, in February 1968, Hewish published a paper in the journal Nature that described the phenomena as a signal from a neutron star — the crushed remnant of a massive star.

The details of the mechanism were not then known — only later astrophysicists described the signal as being a rotating beacon of radiation from the whirling neutron star, or pulsar.

In late 1968, a different team identified the pulsar as being in the center of the Crab Nebula, a supernova remnant (shown at top).

Dress Rehearsal

This story offer parallels to what might happen when astronomers someday stumble across real evidence for E.T.

The SETI folks have set up and published a protocol for how the receipt of an artificial signal would be confirmed and then openly announced to the world. But as with the pulsars, a strange phenomenon may appear when a new window on the universe opens up.

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This could, perhaps, be some kind of future neutrino telescope, or a gravity wave detector. A non-SETI team of researchers could pick up a signal that cannot be explained by any known phenomena. It could take years to rule out any imaginable astrophysical processes.

Meanwhile, in the age of the Internet and social media, I think rumor and speculation would spread vastly faster than it could in 1967. Such a detection could not remain as tightly under wraps as it did back then.

What’s more, if a government funded facility found the signal, it would invite conspiracy theories that the signal is either a fake (for obscure and nefarious political reasons) or, equally, that even more information about the aliens is being covered up — such as sending us blueprints for building a Death Star.

Despite the impact of such a cultural game-changer, I doubt anyone would be tempted to burn the data. There’s a Nobel Prize waiting for the lucky researcher!

Image credits: NASA, Mullard Radio Astronomy Observatory, Lynette Cook (copyrighted by artist)