How to Eavesdrop at a Cosmological Waterhole by Jessica Gorman
Astronomer Frank Drake looks beyond conventional approaches in his continuing search for signs of extraterrestrial life.
The bowl of the Arecibo radio telescope in Puerto Rico stretches 1000 feet across and can hold 357 million boxes' worth of corn flakes. So says astronomer Frank Drake, who has used Arecibo and other radio telescopes since 1960 to search for telltale radio signals from intelligent alien civilizations. Above Arecibo's dish, radio signal receivers hang 50 stories in the air. But even with this mammoth piece of steel, aluminum and concrete, a radio signal from a foreign planet would be easy to miss. More stars need to be examined, more radio frequencies need to be listened to, and bigger and better equipment needs to be built to hear those invisible signals Drake thinks might be bombarding us right now.
Sitting in his Kerr Hall office at the University of California, Santa Cruz, Drake will tell you about the radio telescope he would like to build - its dish will measure 50 miles across.Because bigger is better in radio astronomy, this giant ear on the universe could hear cosmic whispers too faint for even Arecibo. And Drake has the perfect place picked out for it: "Crater Saha, on the far side of the moon. It's just the right shape, 50 miles across."
Drake's giant dream telescope may seem far-fetched to the casual eavesdropper - or to critics of the search for distant technological civilizations. Even to colleagues of Drake, a lunar telescope doesn't sound manageable any time soon. But Project Phoenix, the most-recent form of Drake's life-long research program, is part of a respected Silicon Valley organization called SETI (pronounced "set-tee") - the Search for Extraterrestrial Intelligence - which has roots in NASA. And, this likable astronomer with the big ideas is increasingly gaining the support of the general public and the media - everyone fascinated with the realization, only this past year, that planets do indeed exist beyond our solar system, that life just might have evolved on Mars, and soon, that we might know whether water ice is buried on the moon. So despite budget cuts and the elusive goal of finding a needle in a cosmic haystack, Drake exudes enthusiasm. Even if he isn't getting his big telescope on the moon.
Building on the moon would make sense in Drake's line of work. "The gravity of the moon is about a fifth of what it is on the earth, and that means you can build much bigger antennas," says Drake. The moon would also supply an environment free of gusts of wind that make earth telescopes wobble ever so slightly - but significantly enough to make them unstable if they are not constructed from expensive materials. "The other nice advantage to being there is that you're shielded from radio interference," Drake says. The far side of the moon, which never shows its face to Earth, is the only location in the solar system free of constant interference from human-created radio signals.
But while Drake dreams of building this magnificent telescope one day, and has even used photographs of the lunar surface to plot the future road from the near side of the moon to Crater Saha, he admits that construction will be unlikely - at least before the year 2020. And it will be very, very expensive. "It's not a technical problem," he says matter-of-factly. "It's a money problem." For example: "You have to have a lunar base. That's very expensive."
Seth Shostak, who has worked at the SETI Institute for six years, puts the price tag of Drake's proposed lunar telescope at "hundreds of millions of dollars." Instead, he points out what SETI would do with a more modest surplus of funds. With a few more million dollars coming in each year than now, Project Phoenix would spend it on additional telescope time, Shostak speculates. With $50 million more, SETI could build its own telescope - on earth.
Although the SETI Institute, in Mountain View, California, receives public funding through NASA for most of its research, Project Phoenix was left to fend for itself in 1993, following an ugly defeat in Congress. Other SETI programs included less controversial research, some about the chemical and biological origins of life, while others organized educational materials for teachers. Quickly responding to the setback, Drake and his colleagues enticed technology leaders - including William Hewlett, the late David Packard, Intel co-founder Gordon Moore and the lesser known of Microsoft's co-founders, Paul Allen - to donate millions of dollars to the radio search for extraterrestrial intelligence. Project Phoenix currently functions on a privately funded annual budget of $3 to $4 million, independent of other SETI programs.
Pushing SETI into everyday astronomy, Drake walked a very unusual path. "He is the father of SETI and a mainstream astronomer," says Shostak. "He's kind of the Lewis and Clark of finding our cosmic cousins. He has tremendous insight. That's the reason why Frank is successful."
Drake is quick to separate his work from what he calls pseudoscience: "It's an ongoing battle, because for a large majority of Americans - being bombarded with programs like "In Search Of" - they believe that SETI and UFOs, crop circles and such are all the same thing. It hurt us a lot with the government when we were at NASA because the congress people are just as ignorant."
Later this year though, NASA might just inadvertently help along Drake's dream project, when the space agency launches a mission that will test preliminary suggestions, from the spacecraft Clementine, that water ice is frozen in permanently cold, polar lunar craters. The discovery of water on the moon could reduce some of the costs of building a lunar radio telescope. If water were recycled, only about 100 gallons per person would be needed to support a lunar outpost, Drake estimates. But a lunar base is still only a glint in Drake's eye, and a long-term goal for NASA.
In the real world of 1997, Drake and his colleagues in Project Phoenix patiently scan 1000 of the closest sun-like stars with a radio telescope in Green Bank, West Virginia, in hopes of stumbling upon a glimpse of a distant civilization. So far, they've checked out 400 of the stars on their list, and Drake says he expects to hear something by the year 2000 (though it's coming up "too fast"), when Project Phoenix finishes looking at the last 600. Drake estimates that maybe 10 million civilizations are out there, but only 10,000 are detectable.
Project Phoenix searches the universe for radio signals between the frequencies of 1 gigahertz and 3 gigahertz, where Drake hopes an extraterrestrial civilization might broadcast. "It's because the antennas we use are good on those frequencies, and it's because the universe is extremely dark and quiet on those frequencies," Drake says. "But also in that band are the basic spectral radio lines of hydrogen, the most abundant element in the universe, and hydroxyl, OH. And H plus OH makes water, so we call this the cosmic waterhole." And scientists believe that water is one of the most important resources to sustain life.
"If you're meeting a friend in San Francisco and you can't contact them ahead of time, obviously it's a bad strategy to just go wander the streets of the city. What you do is go to some very prominent place that you know about, and your friend knows about, and you know your friend knows about it, and the friend knows you know about it - and your chances are higher. And that's sort of the logic behind searching the waterhole."
But even with 10,000 extraterrestrial civilizations waiting to be found, chances are that Drake might just be looking in the wrong place, even if he's looking at the right stars. "Much frequency is uncovered," he admits. "Maybe that's why we won't succeed by the year 2000 - we're looking in the wrong band. There's no way to know." But although that concerns him, it doesn't dampen his optimism.
Jill Tarter, Phoenix's project manager, says that Drake is probably the most positive member of the SETI team. Tarter thinks that finding an alien radio signal could be a "generational" project that will succeed eventually, and not necessarily during the lifetimes of the current SETI scientists (although she hopes so). But Drake has strong conviction, she explains. "If you had the opportunity to work on what you think is the most important question to the species, wouldn't you do it?"
Recently, Drake has reason to be confident. Now that the Martian rock and the discovery of new planets have rocked the public and science alike, the media is streaming to his door, and requesting his opinion constantly. In May, he presents a talk to the Queen of the Netherlands. "The Martian rock generated a great deal of interest in space research and particularly in exploring for life in space," Drake says. "And people like to talk to us because the point of the idea is: there's life out there to be found."
"We are a very young technology in a very old galaxy," says Tarter. With this in mind, the SETI scientists figure that any intelligent life they locate will have experienced many more advances than earth culture, which an alien radio signal could share. And the radio astronomers are eager to learn. "It's like giving the Neanderthals a pass to the Library of Congress and teaching them how to read," says Shostak. One day, that just might make an ecstatic Frank Drake the librarian to the world.