CATEGORY 5 INTO THE UNKNOWN

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MESSAGESTO THE

ST SCLASSIFICATION COMMUNICATING WITH ALIENS

Our first messages to the stars are already on their way.Since the early part of the 20th century, radio andtelevision broadcasts, along with the powerful

transmissions from early-warning radars, have been steadilyfanning out through the galaxy in ever-increasing circles.More recently, scientists have deliberately beamed codedsignals into space and equipped space probes with elaboratedetails of human civilization. But no one knows if intelligentlife exists elsewhere to hear our calls.

SEE ALSO ARE WE ALONE?, FIRST CONTACT

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EARTH SOUNDSThe two Voyagerspace probes eachcarry more than 100pictures and 90minutes of sounds,ranging from spokengreetings in manylanguages to thesong of a humpbackwhale and a humanheartbeat.

FAR OUTEven traveling at thespeed of light, thefirst message to bebeamed from Earthto another sta r willtake 24,000 years toreach its target.

STAR BRIGHTBroadcasts wouldmake Earth appearbrighter than the Sunto aliens searchingradio frequencies.

-----------~-----------------~"----"---"-------------------.--ATTEMPTS TO CONTACT ALIENS

RETURN TO SENDERHumans have actively considered sending messages to

the stars since 1820, when the German scientist KarlFriedrich Gauss came up with the idea of cutting

giant patterns in the forests of Siberia and planting wheatin place of the trees. Gauss reasoned that if there wereMartians watching-and if they possessed powerfultelescopes-then they would recognize the patterns assigns of intelligent life on Earth.

Some years later, the Austrian physicist Joseph vonLittrow proposed a similar idea, this time by setting lightto oil-filled trenches in the Sahara Desert. The Frenchphysicist Charles Cros even went so far as to suggestbuilding seven giant mirrors, spread across Europe, tomimic the shape of the Big Dipper.

The first radio message deliberately aimed at life-formson other worlds was designed by Frank Drake, a pioneerof SET! (Search for Extraterrestrial Intelligence).Consisting of a string of pulses that could be assembled toform a simple picture, it was beamed in 1974 from the

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D<> Th~y L<>,,~ L~c::y? .~,LARGE-SCALE RADIO BROADCASTS BEGAN IN ~~~;""K1'!f ....•~4'" .~. :

THE 1920s AND WERE FOLLOWED BY MORE '.. .\~ ~ ..".. ' ~ •POWERFUL TV BROADCASTS 20 YEARS LATER. f'"A f;,.~~(1

By NOW, EARLY TV SHOWS SUCH AS I LOVE l.i1Jll .;,.;»1LuCY (RIGHT) HAVE FANNED OUT THROUGH ~ .!!!!!B-SPACE IN A SPHERE THAT MEASURES ABOUT 50 •. . ..'.••••..•..'i. ~.'

LIGHT-YEARS IN RADIUS AND CONTAINS ~4IiiiiII!ITHOUSANDS OF STARS. AT THIS DISTANCE, THEY COULD EASILY BE DETEmD BYRADIO TElESCOPES ONLY A FEW TIMES MORE SENSITIVE THAN THE ARECIBO DISH.

TRUE STORY

giant I,OOO-footradio telescope at Arecibo in Puerto Rico.In fact, the message was partly a publicity stunt to markthe telescope's recent upgrading. And since its destinationis a globular cluster some 24,000 light-years away, no oneis expecting a quick reply.

Specicd DeliV"erySome two years before the radio message wasbeamed, Drake participated in a more seriouseffort. Pioneers 10 and 11, launched in 1972 and1973, were the first spacecraft destined to leavethe solar system. On board they carried apicture message-in the form of an engravingon a gold-plated aluminum plaque-devisedby Drake and space scientist Carl Sagan.

Both probes have long since successfullycompleted their missions, beaming back thefirst close-up pittures of Jupiter and Saturn,and are now passing through the outer reachesof the solar system. Even so, it will be tens ofthousands of years before they pass close toanother star, so there is only a small chancethat an alien civilization will encounter them.

In 1977 other missions to the outer planetsand beyond were launched. This time theprobes-Voyagers 1 and 2-carried old-stylelong-playing records, made not of vinyl but ofcopper and containing not just music andspeech but pictures, too. Like the Pioneer craft,these probes have now left the Sun farbehind. Who knows if anyone-oranything-will ever find them?

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•••WE PICK UP A SIGNAL-SHOULD WE SEND A REPLY?Some scientists are concerned that a message from

outer space could start a panic, or create a sense ofdespair when people realize they are not the mostadvanced creatures in the universe. Others are justplain scared, as astronomer Frank Drake discoveredwhen he used the Arecibo telescope to send his famouscoded radio message in 1974. Britain's AstronomerRoyal, Sir Martin Ryle, immediately wrote to theLondon Times newspaper, arguing that such atransmission could reveal our existence and location toother beings, who might be unfriendly. Time and againin our own history, noted Ryle, entire civilizations havebeen enslaved or wiped out when theywere discovered by societies with moreadvanced technologies. He then calledupon the International AstronomicalUnion to ban such messages in future.

As for any incoming signal, theastrophysicist Zdenek Kopal put thingsbluntly: "If the cosmic telephone rings, forGod's sake let us not answer."

In reply, Drake pointed out that it wasalready too late: We have long since givenour existence away with 75 years of radio,TV and radar signals. He also suggested,perhaps optimistically, that societies thatwere both sufficiently warlike and

Assuming that technologically advanced aliens wereable to decode our TV broadcasts, there is noguarantee that they would make sense of them-after all, even Earthbound humans sometimes findthat difficult. "Intelligent life on Earth? Don't beridiculous, Hivemaster."

technologically advanced enough to cross interstellarspace were likely to destroy themselves long beforethey could threaten the civilizations of other stars. Wecan only hope that Drake is right.

Our own television output may well leave older,wiser life-forms unimpressed-even disgusted-if theychance upon a violent movie, or one of the countlessnews broadcasts that report what human beings do toeach other. It also seems unlikely that aliens will shareour sense of humor: If they conclude that the movieDumb and Dumber reflects day-to-day life on Earth, thechances are their opinion of us will not be very high.

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