Astronomy Now Home

SETI: Cosmic Call
Posted: 3 May 2010

Bookmark and Share

Despite fifty years of searching, there is still no sign of little green men. SETI researchers will point out that if the Galaxy were an ocean, we’ve searched the equivalent of a beaker’s worth of water. The cynical suggest that the reason we’ve not found anyone is because there is nobody out there. It’s a depressing thought, but there are alternatives. One possible explanation is that perhaps everyone in the Galaxy is shy; rather than a cosmos full of chatterboxes, we live in a Universe where everybody is too afraid to speak up, meaning that everybody is listening, but nobody is talking. If nobody is transmitting, nobody will ever receive a message and everyone in the Galaxy will think they are alone.

Russian radio astronomer Dr Alexander Zaitsev, of the Russian Academy of Science in Moscow, calls this the ‘SETI Paradox’. Not to be confused with the famous Fermi Paradox (although it is certainly a facet of it), Zaitsev sees his paradox as a kind of vicious circle – no aliens are transmitting, so we don’t hear anything, and we’re not transmitting, so aliens have no idea that we are here and waiting for their call. The way to break this cycle, he says, is for humanity to begin transmitting. The practice of broadcasting to ET is called METI (Messaging Extraterrestrial Intelligence), and sometimes it is also described as ‘Active SETI’, but Zaitsev delineates between the two by quoting one of SETI’s great pioneers, Nikolay Kardashev, who wrote in 1964 that “there are reasons to believe that transmission of information is one of the basic conditions of the existence of supercivilisations.”

An artistic impression of the planets belonging to the Gliese 581 system. Alexander Zaitsev has beamed a message to these planets in the hope that someone there will receive it. Image: ESO.

“Kardashev was not talking about Active SETI, where the main goal is just to attract ET’s attention as part of our search,” explains Zaitsev. “Kardashev talked about more serious things, about the vital need to communicate – the ‘basic conditions of existence’.” In other words, what Kardashev and Alexander Zaitsev are saying is that to truly understand the Universe, civilisations have to be able to reach out to one another and communicate their thoughts and ideas.

Targeting Goldilocks
We’ve beamed a few messages to the stars over the last 36 years. Frank Drake and Carl Sagan used the giant radio telescope at Arecibo in 1974 to send a pictogram to the inhabitants of the globular cluster M13 – it should get there in about 25,000 years, but to anyone watching the Sun will temporarily become the brightest object at radio wavelengths outside of the galactic centre. More short-distance calls are being made by Zaitsev, who has taken it upon himself to try to initiate contact between worlds, overseeing the broadcast of four different messages to a handful of nearby stars using the 70-metre radio telescope at Evpatoria, on the Crimean Peninsula of the Ukraine. Two of his radio blasts to the stars, Cosmic Calls 1 and 2, were pictograms broadcast at 5.01 GHz, which is the standard operating frequency of the Evpatoria dish, with a maximum power of 1.3 x 1012 watts. Targeting Sun-like stars within 70 light years, the first Cosmic Call was beamed towards four separate star systems, 16 Cyg A, Gliese 777, HD 178428 and 15 Sge, whilst Cosmic Call II reached out to five stars, including 47 UMa and 55 Cancri, the latter of which harbours an exceptional planetary system. Over the last fourteen years five worlds have been discovered revolving around this star, 40.9 light years away. Its innermost planet, a world designated as 55 Cancri ‘e’, is a rocky ‘superearth’ with a mass similar to Neptune, whereas its siblings are even more massive planets made purely of gas. Although none of these worlds will be inhabitable, there is a huge swath of space between the fourth planet, 117 million kilometres from the star, and the outermost (known) planet at 863 million kilometres. This space encompasses the star’s habitable ‘Goldilocks’ zone (where temperatures are just right for liquid water) and where more planets may be lurking. Planets have also been discovered around 16 Cyg A, Gliese 777 and 47 UMa, while a brown dwarf was found orbiting 15 Sge in 2002.

The Arecibo ‘blast’ that was beamed out towards the star cluster M13 in 1974. It will take 25,000 years to reach its destination. Transmitted as binary code, the opening line describes the numbers 1 to 10 in binary form, just in case ET doesn’t understand binary. The next three lines give the atomic numbers of the five most important elements in living cells – hydrogen, carbon, nitrogen, oxygen and phosphorous. Then comes a representation of the DNA double helix, with the number four million running down the spine of the helix, indicating the number of characters in the genetic code. After this is a stick man illustration of a human being. The line that extends from head to toe of this stick man and the number 14 (in binary). Fourteen multiplied by the wavelength of the message – 12.6cm – gives 176cm, the average height of a human being. On the left of the stick man is the number four billion, the population on Earth at the time. Afterwards comes a line with the nine planets (Pluto was still a planet at the time) and the Sun on the right, with Earth highlighted. Then there is a crude representation of Arecibo itself, and its size of 305 metres again shown as a multiple of the signal’s wavelength, 12.6cm. Whether this is something that ET could understand is debatable – not that many humans can decipher it!

Alexander Zaitsev continued targeting stars with known exoplanets around them with his other two signalling efforts. Teen Age Message blasted towards six stars, including 47 UMa, in 2001, while his most recent endeavour, Message From Earth, in October 2008, was sent towards the Gliese 581 planetary system of five worlds orbiting a dim red dwarf 20.3 light years from us. All the planets could easily fit inside the orbit of Mercury, but as a cool star, Gliese 581’s habitable zone is much closer to it than in our Solar System. One of the planets, Gliese 581 ‘c’, skirts the inside edge of the Goldilocks region, orbiting its star every 13 days. Living on this planet would seem very strange to us; with a mass of at least five Earths and a diameter estimated to be one and a half times that of Earth (approximately 19,000 kilometres), you would feel the pull of gravity at your feet to be more than twice as strong as on the surface of Earth, while a dull red sun hangs motionless in the sky, never appearing to move as the planet is forced to face the same hemisphere towards the star much like the face of the Moon is locked towards Earth. It would feel hot too, with an effective surface temperature of 40 degrees Celsius, depending of course on local environmental conditions and location on the planet. Still, as weird as this world sounds, it perhaps could be home to some kind of alien life, and within two decades they may be listening to Zaitsev’s Message From Earth.

Messages from Earth
These five broadcasts are, even as we speak, permeating the depths of space along with a wash of faint television, radio and mobile phone chatter, more powerful radar surges emitted from military facilities and Arecibo, and a selection of less serious attempts to hail ET, mostly publicity stunts such as Beatles songs and Doritos adverts that Zaitsev calls ‘pseudo METI’.

What distinguishes the more serious attempts at opening hailing frequencies with lifeforms out there from the interstellar spam that we send out with regularity is of course content. The trouble is that the gulf between ourselves and an alien civilisation may be so great that our words could be indecipherable, with our greatest works of literature indistinguishable from an advert for a savoury snack in the mind of an alien being. Some scientists advocate sending ET our scientific knowledge, but do aliens, perhaps millions of years in advance of ourselves, really need a lesson in science and mathematics? Maybe instead they would be curious about what we and our planet look like. The 1974 Arecibo blast at 2.38GHz contained 1,679 characters in binary code, where all the zeroes and ones were distinguished by two slightly different frequencies. Once decoded the message depicts simple images of the type you would expect on an old home computer of 30 years ago, which are supposed to tell any aliens tuning in about DNA, the appearance of human beings (as a stick figure), the Arecibo radio telescope, where Earth is located in the Solar System, our planet’s population, and of course an explanation of binary code, should the aliens not be able to figure it out themselves. A ‘Rosetta stone’ for decryption is actually vital for any interstellar communication – we’re certainly hoping that ET packages one with its messages.

Alexander Zaitsev’s Cosmic Calls also incorporated a Rosetta stone. Designed by Canadian scientists Yvan Dutil and Stepháne Dumas, it consisted of 263,906 bits of information (encoded into the signal by shifting the transmission frequency up or down to represent a black or white pixel) that builds up into 127 x 127 pixel images of people, nature, and examples of our culture. The second Cosmic Call also included 50 personal messages from individuals as diverse as David Bowie and Ukranian schoolchildren. Meanwhile, Russian teenagers helped craft the ‘Teen-Age Message (TAM) to the Stars’, again including personal greetings, messages and music (produced using a theremin, an electronic instrument synonymous with the eerie sounds from 1950s science fiction B-movies, and thereby representing analog rather than digital information; having a multi-layered structure of both digital and analogue information in the message is to compensate for the uncertainty of whether digital or analogue is more easily understood by extraterrestrials, says Zaitsev). Finally, Zaitsev’s most recent Message From Earth beamed greetings from users of the social networking site Bebo towards its target. By involving schoolchildren and members of the public, and creating publicity from celebrity participation, METI is helping to create a greater awareness amongst the general populace about the Universe at large. Even if METI fails to communicate with any extraterrestrial intelligences, it can be regarded as having succeeded in at least helping to communicate science to our own people.

As far as Zaitsev is concerned, METI is just beginning. The construction of a new 70-metre dish called the Russian Radar Astronomy Telescope in the far east of Russia is set to be completed by 2013, and as well as radar research on space debris, near-Earth objects and other planetary bodies in our Solar System, it will also be used to transmit messages from Earth. “With this first special METI instrument we can include many more stars,” says Zaitsev. This should vastly increase on the 41 hours of total METI transmission time that humans have conducted so far, in comparison to the years spent searching. METI is about to hit the big time, but with radar and powerful broadcasting facilities becoming more available to a wider range of people, should we be looking to regulate transmissions to the stars?

In the next part of this article series we’ll encounter criticism of METI, and meet some scientists who are so vehemently opposed to METI, at least until we know more about what lies in wait of us ‘out there’, to the extent that they have resigned from important roles in the International Academy of Astronautics’ SETI ‘Post Detection Taskgroup’. Who should speak for Earth, and is it wise to holler into the jungle?

Stay tuned throughout April for more SETI articles.

Find out more: The San Marino Scale
In 2005, a new measure of signals transmitted from Earth was proposed by Paul Schuch of the SETI League and Professor Iván Almár of the Hungarian Academy of Sciences at the Sixth World Symposium about Space Exploration and Life in the Universe in San Marino. The San Marino Scale, as it was hence known, quantifies messages from Earth based on signal strength (I) and information content (C). Adding the two factors together, each of which are given a value out of five, gives the San Marino index out of ten. It’s a bit like the Richter Scale for earthquakes, or the Torino Scale for asteroid impacts. Schuch and Almár have applied the San Marino Scale to both Alexander Zaitsev’s Cosmic Calls and his Teen Age Message, and found them to rate at 7, which is high on the scale. The 1974 Arecibo transmission was even stronger, rating an 8, which is far-reaching. Radar observations of Near-Earth Objects (asteroids), meanwhile, rate just 6 (noteworthy). You can experiment with the San Marino Scale calculator at