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Researchers In Puerto Rico Try Tuning In -- To Extraterrestrials
By Matthew Hay Brown
November 29, 2002
ARECIBO, Puerto Rico -- Ask one of the few full-timers involved in the search for extraterrestrial intelligence when proof of alien life will be found, and a funny thing happens.
Almost invariably, Peter Backus said, the answer corresponds with the number of years left in the searcher's career.
Backus laughed: It's his disclaimer before he answered the question himself. The 49-year-old astronomer, head of observations for the most sensitive search for extraterrestrial intelligence ever conducted, said increasingly larger, faster and more sensitive instruments may make it possible to find evidence of alien technology within the next 10 to 15 years.
"I can only imagine the feeling of making a discovery of the magnitude of finding another civilization," he said. "People have been asking, 'Are we alone?' for thousands of years. We may be doing the experiment that will answer the question."
The search resumes tonight, when Backus and his colleagues from the SETI Institute of Mountain View, Calif., take over the controls at the world's largest radio telescope, here in the mountainous karst region of north-central Puerto Rico. For the next two weeks, they will be using Earth's most sensitive receiver to scan the heavenly dial for extraterrestrial broadcasts.
Using the Arecibo Observatory twice a year, the astronomers of Project Phoenix have made it roughly halfway through their examination of about 800 nearby sunlike stars, considered most likely to be orbited by planets that could support recognizable intelligence.
No aliens so far
The astronomers are looking for evidence of alien technology -- radio waves such as those produced by humans for television broadcasts and satellite telecommunications.
To date, they have found none. Project Phoenix -- it rose from the ashes of a NASA program canceled by Congress in 1993 -- already has ruled out the existence of Earthlike technology within 150 light-years of the solar system. If someone out there were communicating as humans do here, the searchers would have heard them.
Nonetheless, these are exciting times for the SETI crowd. The Allen Telescope Array, to be ready at the University of California at Berkeley's Hat Creek Observatory by 2005, will speed the current Project Phoenix search 100 times over. The proposed Square-Kilometer Array, an international project that could be built in the United States, Australia or China, would capture fainter and more-distant radio transmissions with higher resolution.
A dish now under construction at Harvard University's Oak Ridge Station in central Massachusetts will be able to identify distant optical signals, another possible expression of alien intelligence. The proposed Omnidirectional SETI Search would link millions of antennas to look for microwave signals.
And the Kepler spacecraft, to be launched by NASA in 2007, will search the universe for Earthlike planets. Any discoveries would give SETI investigators new worlds to explore.
"Our ability to find things keeps getting better," SETI Institute astronomer Seth Shostak said. "This is like being aboard the Niña, the Pinta or the Santa Maria, only the ships keep getting faster, and the ideas from the crew keep getting more interesting."
At the Arecibo Observatory this afternoon, from an air-conditioned control room beside the 1,000-foot dish, Backus will type a simple command into a desktop keyboard, and the search will pick up where it left off last spring. Focusing on one star at a time, the Project Phoenix supercomputer examines about 1.8 billion channels, ignoring the broad radio splashes produced by natural phenomena for the narrow-band signal of an intentional broadcast by a technological civilization.
SETI investigators think such a signal could be an interstellar beacon, as was broadcast from Arecibo in 1974, when SETI pioneer Frank Drake used what is also Earth's most powerful transmitter to send a pictograph that showed a human figure, the structure of DNA and the solar system. Or it could be simply the hum of a technological society, such as Earth has produced continuously since the advent of television.
A second dish, the 250-foot Lovell Telescope at Jodrell Bank Observatory in England, serves as a backup to the Arecibo observations. Together, they can rule out interference from earthly sources -- the cell phones, broadcast towers and satellites that now block more than a quarter of the frequency range the astronomers are searching. If both telescopes identify a candidate signal, the supercomputer conducts more tests and alerts the astronomers.
"We check to make sure the champagne is on ice," Backus joked.
Should a signal survive the tests, the astronomers would contact observatories around the world for independent verification and begin the process of notifying humankind.
'A question of loneliness'
Visions of that day have fired the imaginations of scientists and dreamers at least since classical Greece.
"Possibly it's a question of loneliness," said Charlene Anderson, associate director of the Planetary Society. "Humanity sees itself on top of the evolutionary ladder. We look around, and there's no one to talk to.
"Is there someone else who has developed beyond where we have developed? Who got to the stage where they had the means to destroy their environment and can tell us how they passed through that phase?"
The SETI Institute employs a psychologist as "interstellar message group leader," whose job is to think about an appropriate response to an alien message. The International Academy of Astronautics and the International Institute of Space Law have sent a white paper on key issues in extraterrestrial communication to the U.N. Committee on the Peaceful Uses of Outer Space.
But unless the signal were a simple beacon, Shostak said, it would be unlikely that humans would understand it. Any civilization that could be detected from Earth is likely to be so far advanced, he said, that human attempts at eavesdropping would be similar to ants trying to listen to humans.
Messages might take millennia
Attempts at two-way communication would face additional challenges. Given the vast distances involved, speed-of-light transmissions could take centuries or millennia to arrive.
"I don't find that terribly dismaying," Shostak said. "The real message is that you picked up the signal. It would tell us that we are not alone and that this little world we get so exercised about is just a small part of the universe."
But for now, the champagne remains corked. More than 40 years after Drake first pointed a radio telescope at two nearby stars in search of an intentional transmission, scientists have yet to find credible evidence of extraterrestrial intelligence.
Backus, who is spending his career on the search, said he is skeptical himself.
"I would be willing to bet a substantial amount of money that there is simple life somewhere else in the universe, something on the level of bacteria," he said. "Whether there is life that is complex, that develops technology, that's the big question. . . . The only way to know for sure is to do the experiment."