The wide dishes, 20 feet across and raised high on their pedestals, creaked and groaned as the winds from an approaching snowstorm pushed into this highland valley. Forty-two in all, the radio telescopes laid out in view of some of California’s tallest mountains look otherworldly, and now their sounds conjured up visions of deep-space denizens as well.
The instruments, the initial phase of the planned 350-dish Allen Telescope Array, are designed to systematically scan the skies for radio signals sent by advanced civilizations from distant star systems and planets. Fifty years after it began ó and 18 years since Congress voted to strip taxpayer money from the effort ó the nation’s search for extraterrestrial intelligence is alive and growing.
“I think there’s been a real sea change in how the public views life in the universe and the search for intelligent life,” said Jill Tarter, a founder of the nonprofit SETI Institute and the person on whom Carl Sagan’s book “Contact,” and the movie that followed, were loosely based.
“We’re finding new extra-solar planets every week,” she said. “We now know microbes can live in extreme environments on Earth thought to be impossible for life not very long ago, and so many more things seem possible in terms of life beyond Earth.”
The Hat Creek array, which began operation two years ago, is a joint project of the SETI Institute and the nearby radio astronomy laboratory of the University of California at Berkeley. Made possible by an almost $25 million donation from Microsoft co-founder Paul Allen, the array is unique and on the cutting edge of radio astronomy. SETI and Berkeley share both the facility, 290 miles northeast of San Francisco, and all the data it collects.
The dishes also represent a coming-of-age for SETI Institute enthusiasts and its sometimes hailed, sometimes ridiculed mission. While their effort was long associated with UFOs, over-excited researchers and little green men, it is now broadly embraced as important and rigorous science, and astronomers and astrobiologists in an increasing number of nations have become involved in parallel efforts.
“This is legitimate science, and there’s a great deal of public interest in it,” said Alan Stern, a former assistant administrator at NASA who, in 2007, decided that proposals for extraterrestrial search programs should not be banned from the agency, as they had been since the early 1990s. The National Science Foundation had come to a similar decision a few years before.
“It was not a big or difficult decision to change the policy,” said Stern, who invited Tarter in to describe her program to NASA officials. “The technology and science had advanced, and so it made no sense to block applications.”
Limited search programs for intelligent extraterrestrials in the 1970s and 1980s abruptly lost their federal funding in 1992, after NASA proposed a greater effort. Former Sen. Richard Bryan, D-Nev., led the charge in Congress, telling the Senate at one point: “The Great Martian Chase may finally come to an end. As of today, millions have been spent and we have yet to bag a single little green fellow. Not a single Martian has said, ëTake me to your leader,’ and not a single flying saucer has applied for FAA approval.”
The funding was eliminated, even though SETI listens for radio signals from distant planets and has nothing to do with Mars or with a supposed search for flying saucers or other space oddities.
But when NASA informed Congress that it was going to allow SETI to once again compete for funds, there were no objections, Stern said. Rita Colwell, who was director of the National Science Foundation when it approved a small-scale SETI Institute proposal in 2004, said several prominent astronomers endorsed the group, saying that the institute had become an important player in the field of radio astronomy.
Still, search activity by the institute and others is often criticized for its lack of results. It has been 50 years since astronomer Frank Drake first used a radio antenna at the Green Bank National Radio Astronomy Observatory in West Virginia to listen for extraterrestrial signals, and so far no messages have been detected and confirmed. UCLA physicist and astronomer Ben Zuckerman often lectures on what he considers the overly optimistic predictions of search advocates, and he argues that if the Milky Way were home to technologically advanced civilizations we would know it by now. “I think very strong arguments can be brought to bear that the number of technological civilizations in the galaxy is one ó us,” he said.
Although disappointing to scientists searching for intelligent life beyond Earth, the absence of contact is something they consider far from surprising. As Tarter described the effort, the number of star systems studied so far for possible communications is minuscule compared with the number of stars in the sky ó on the same scale as if a person searched for a fish in the Earth’s combined oceans by drawing out a single cup of water.
“The chances of finding a fish in that one cup are obviously very small,” she said. As she and others often point out, astronomers think the universe contains something on the order of 1,000,000,000,000,000,000,000,000 stars and, given the discovery so far of more than 400 extra-solar planets, it is generally assumed that billions or trillions more are orbiting in distant systems.
What’s more, it remains far from certain that listening for radio signals is the right approach. Radio is a relatively primitive form of communication, and advanced civilizations could be sending signals in many different ways. Given that possibility, astronomers have begun using optical telescopes to search for nanosecond laser blips and beeps that might be coming our way.
A Harvard-Princeton University collaboration has resulted in some of the most sophisticated optical searches, and the effort now has worldwide appeal. In November, for instance, a group of 30 optical and radio observatories and amateur astronomers dedicated two nights to simultaneously viewing one particular star system in search of radio signals or laser pulses. The effort, led by Shin-ya Narusawa of the Nishi-Harima Observatory in southern Japan, targeted a system described in 1993 by Sagan and Paul Horowitz (leader of the optical search team at Harvard) as potentially habitable.
“In Japan, our telescopes are all open to the regular people, and when they come in we want to know what are their big interests in astronomy,” Narusawa said during the nighttime observation. “The top two are these: Is there an end, a border, to the universe? And is there life, especially intelligent life, anywhere other than Earth?”
Narusawa said he hoped to cooperate with the SETI Institute in the future, as well as with more fledgling SETI programs in South Korea and Australia.
