Is strange space signal a sign that ET's mother has called back?

AMATEUR radio hams are usually excited by the faint buzz of a distant shortwave station, but a group of scientists believe they have received a message from extra-terrestrials.

Astronomers think that a signal picked up by a radio telescope last year shows the highest probability yet that ET’s family may have returned his call.

In February 2003, scientists involved in the search for extra-terrestrial intelligence (SETI) pointed the huge radio telescope in Arecibo, Puerto Rico, at about 200 sections of the sky.

Unexplained radio signals had been detected twice by the same telescope in these areas and scientists were trying to confirm the findings.

It may sound fanciful, but a report in the journal NewScientist reveals how the team has now finished analysing the data, and all the signals seem to have disappeared - except for one which has got stronger. Detected on three separate occasions, the signal is "an enigma", say researchers.

So far, explanations have included conjecture that it could be generated by a previously unknown astronomical phenomenon, or may even be something far more pedestrian, such as an artefact on the telescope itself interfering with measurements.

But the astronomy team says that it also happens to be the best candidate yet for a contact by intelligent aliens in the six-year history of the SETI@home project, which uses programmes running as screen-savers on millions of personal computers worldwide to sift through signals picked up by the Arecibo telescope.

Dr Dan Wertheimer, a radio astronomer at the University of California (Berkeley) and the chief scientist for the project, said: "It is the most interesting signal from SETI@home. We are not jumping up and down, but we are continuing to observe it."

Named SHGb02+14a, the possible alien communication has a frequency of about 1420 megahertz - one of the main frequencies at which hydrogen, the most common element in the universe, readily absorbs and emits energy.

Some astronomers have suggested that aliens trying to announce their presence would be likely to transmit at this frequency, and SETI researchers regularly scan this part of the radio spectrum.

The unexplained signal appears to be emanating from a point between the constellations of Pisces and Aries, where there is no obvious star or planetary system within 1,000 light years, and the transmission is also very faint.

Dr Eric Korpela, of the research team, said: "We are looking for something that screams out ‘artificial’. This just doesn’t do that, but it could be because it is distant."

So far, the telescope has managed to pick up the signal for only about a minute in total, which is not sufficient for astronomers to analyse it fully.

Dr Korpela believes that it is unlikely the "message" is the result of any obvious radio interference or noise, and it does not resemble any known astronomical object.

Others, however, are more sceptical, saying the current lack of explanation does not mean that it could only have been produced by aliens.

Dr Jocelyn Bell Burnell, of the University of Bath, said: "It may be a natural phenomenon of a previously undreamed-of kind - like I stumbled over."

It was Dr Bell Burnell who, in 1967, observed a pulsed radio signal which the research team at the time believed was from extra-terrestrials, but which later was confirmed as the first sighting ever of a spinning collapsed star.

Other questions arise over the signal’s frequency, which oscillates by between eight and 37 hertz a second.

Paul Horowitz, a Harvard University astronomer who looks for alien signals using optical telescopes, believes that the drift in the signal makes it "fishy".

David Anderson, the director of the SETI@home project, is also sceptical but curious about the signal. He told NewScientist: "It is unlikely to be real, but we will definitely continue to observe it."

Meanwhile, a new analysis of interstellar communications claims that, rather than sending radio signals, aliens would find it far more efficient to send a "message in a bottle".

Scientists at Rutgers University in New Jersey claim that beaming a radio signal that can be detected 10,000 light years away would demand a million billion times as much energy as just shooting out matter on which the data is inscribed.

Well according to SETI...

Reports of SETI@home Extraterrestrial Signal Highly Exaggerated
by Amir Alexander

September 2, 2004:

A rash of reports in recent days that SETI@home has discovered a likely signal from an alien civilization are highly exaggerated, says SETI@home Chief Scientist Dan Werthimer of U.C. Berkeley.

The storm was initiated by an article in New Scientist magazine, which reported about SETI@home’s most promising candidate signal to date, and speculated about its possible origins. Like all of SETI@home’s 5 billion potential signals, this candidate, labeled SHGb02+14a, was assigned a numerical score representing the statistical likelihood that it is indeed an intelligent extraterrestrial signal. Its relatively high score placed it among the 200 “top candidates” selected for the targeted reobservation sessions that took place in March of 2003 at the Arecibo Radio Observaotry. Of all the candidates targeted in the sessions, however, SHGb02+14a was one of the very few to be confirmed during the reobservations, and the only one whose score following the sessions actually went up.

A sky map of the reobservations that took place at Arecibo in March of 2003. The blue areas represent the plane of the Milky Way, the gray strip the band of sky seen from Arecibo. The squares mark the locations of the signal candidates revisited during the reobservation sessions.
Image: University of California/SETI@home

While this makes SHGb02+14a interesting, the chances that it actually represents an intelligent signal from beyond remain extremely slim. Random chance alone would make it probable that at least one of the billions of candidates detected by SETI@home would be observed on three separate occasions, as was the case for this candidate. Furthermore, as we reported in the SETI@home Update of May 17, 2004, the fact that this candidate’s frequency drifts rapidly makes it extremely improbable that it is a transmission from extraterrestrials. Because of the drift, explained Werthimer, “if we had looked at the sky even a few seconds later we wouldn’t have found a match” for this candidate. A signal that drifts so quickly that it can only be heard for seconds at a time at a given frequency can only be detected by blind luck. Needless to say, such a transmission is an unlikely vehicle for message from an advanced civilization.

In addition, SETI@home Project Director David Anderson of U.C. Berkeley pointed out that SHGb02+14a is a candidate of a type known as a "barycentrically corrected gaussian." A true transmission of this type, he explained, would remain in a more or less fixed narrow-band frequency, and not drift rapidly as this signal does.

At Arecibo the giant radio telescope still scans the sky, looking for an alien transmission. Around the world, millions are still crunching SETI@home data on their personal computers. The Search for extraterrestrial intelligence continues at full speed, but as of now there is no breakthrough.

Of course, this could change at any time… We promise to keep you posted.

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