Green Bank scans cosmos for signs of intelligent life Radiotelescopes continue the search 24 hours a day

THE BALTIMORE SUN

GREEN BANK, W.Va. - The big dish swung across the sky and pointed at a star whose rays had sped through space for 19 years, until they reached this valley nestled among the peaks of the Allegheny Mountains.

"All these have the right drift," Dr. John W. Dreher, who once taught at the Massachusetts Institute of Technology and now works full time for the SETI Institute as its systems scientist. Dreher peered at the incoming signals, three tantalizing blips on his computer screen. "If there is an ET signal in here, it would look just like these."

The 140-foot radiotelescope wheeled overhead, tracking the star through the sky. Nearby, a computer the size of a truck trailer compared readings from the big dish with ones relayed from a radio telescope hundreds of miles away in Georgia.

The computer searched the static for a signal, a pattern, a message, any sign that the tantalizing blips were not just terrestrial noise but rather the answer to a question as old as homo sapiens: Are we alone in the universe?

Here and at other sites around the world, scientists are quietly accelerating their hunt for signs of alien life, an activity known as the Search for Extraterrestrial Intelligence, or SETI.

'Prepared for success'

"We're always prepared for success," said Dr. Peter Backus, one of the SETI experts here. "We have a bottle of champagne on ice."

The SETI Institute, a private research group in Mountain View, Calif., pays roughly $6,000 a day to rent the telescope here at National Radio Astronomy Observatory, a federal center in Green Bank run by the National Science Foundation. It uses the big dish antenna one-quarter of the available time each year.

In the next year or two, whenever a telescope being built here is finished for radio astronomers engaged in more traditional pursuits, the SETI Institute plans to use the 140-foot radiotelescope, or antenna, full time. SETI enthusiasts say the hunt will almost certainly pay off.

Search began in 1960

The global search for signs of extraterrestrial intelligence began here in 1960. The observatory was brand-new and Dr. Frank D. Drake, a staff astronomer, pointed an 85-foot antenna at Tau Ceti and Epsilon Eridani, nearby sunlike stars that might harbor planets. He called the project Ozma, after the princess of the Oz books.

Drake was proud of this historic test even though, he wrote later, "we could discern no trace of an intelligent signal." Finding signs of extraterrestrial life, he decided, might require the study of "billions more stars."

Inspired by the hunt, like-minded experts gathered here in 1961 for a conference that featured Drake and such future scientific stars as Dr. Carl Sagan, then a brash 27-year-old astronomer. The group decided that Earth's galaxy, the Milky Way, with its billions of stars, could in theory shelter between 1,000 and 100,000 advanced civilizations, many with powerful transmitters and other technologies that might be detected from afar.

The group agreed that an active search was warranted. Other scientists scoffed, but Sagan argued passionately for the search - and he pressed the case throughout his career as an astronomer, science popularizer and author. Sagan died at 62 last year.

Drake now heads the SETI Institute, which took over a federal extraterrestrial hunt after government funds were withdrawn in 1993. The government invested $58 million in developing receivers and other gear before pulling the plug.

The private patrons of Project Phoenix, as it is known, include such technology pioneers as William R. Hewlett and David Packard of the Hewlett-Packard Corp.; Gordon Moore, co-founder of the Intel Corp.; and Paul Allen, co-founder of the Microsoft Corp.

It is West Virginia where the search is reaching a new seriousness, nearly four decades after the Ozma project. The JTC hunt, SETI's most sensitive and comprehensive, aims to scrutinize about a thousand sunlike stars in Earth's neighborhood.

A visitor driving through the mountains quickly gets a hint of why the telescope was built there. The car radio scans endlessly, finding no stations.

Optical telescopes are set atop mountains to limit atmospheric "twinkles" that mar observations. Radiotelescopes are put in valleys because their rocky flanks block interference from radio waves.

The deep green of this valley is dotted with seven white telescopes, their dishes set at different angles.

The radio quiet here is reinforced by a federal ban on commercial radio and television transmissions. At the observatory, all vehicles are powered by diesel engines, which have no spark plugs.

"No visitor cars beyond this gate," a sign says. "Ignitions interfere with telescopes."

The 140-foot-wide telescope pointed straight up, as tall as a 20-story building. Attached high on its side was a Project Phoenix banner.

Observations here began last October and have included Epsilon Eridani, one of the Ozma targets, as well as three stars recently discovered to have planets. In May, Drake spent a week at the telescope.

The interior of its base houses a cavernous room filled with electronic gear and computer racks. Dreher moved back and forth among four glowing monitors, readying the telescope.

'Excessively complicated'

"It's excessively complicated," he said, typing away. The obscure command "tkgnats" appeared on a glowing screen.

The equipment scans each target star on 2 billion radio channels, a job that takes hours. Astronomers pick targets and help the supercomputer judge which signals look most intriguing. It is a constant struggle to weed out transmissions from satellites, cell phones and passing trucks.

"We've built a system that's highly engineered to detect artificial signals," Dreher remarked, "so we detect them by the millions."

One oft-repeated test of observational power is to point the telescope at Pioneer 10, the most distant of human probes, now far beyond Pluto. The craft's signal, traveling at the speed of light, takes about nine hours to make its way back to Earth and the radio telescope here.

SETI scientists hope to pick up alien signals beamed in Earth's direction on purpose or by accident.

Inadvertent signals might include radio broadcasts, satellite communications, instructions beamed to spacecraft and messages sent between space stations and home planets.

As Dreher worked at the computer, it responded by serving up a list of 35 or so candidate stars that would be in view during this observing session. He selected from the institute's catalog 4049, its number indicating a relatively dim star system 19 light-years away. Invisible to the naked eye and near the constellation Libra, it has no common name.

The telescope locked on the star 27.889 degrees above the horizon as it rose in the sky.

In less than an hour of hunting and analysis, after sorting through a thicket of celestial and earthly interference, the system came up with three intriguing signals. "This is particularly interesting," Dreher said as he eyed a glowing blip. "It's a pretty good candidate."

Eliminating a target

Now the analysis swung into high gear with the Follow Up Detection Device, known as FUDD. Its computerized job is to compare readings with a telescope in Georgia and confirm that detected intelligent signals are genuine.

"NoConfirm rfi," read the screen's message, "rfi" standing for what had actually been detected: radio frequency interference.

"OK," Dreher said with a shrug, "it eliminated all those targets."

With a few clicks of a computer mouse, he turned the telescope's operation over to the SETI Institute in California and a remote control room that handles much of the searching.

Over dinner, Dreher sketched out an ambitious program of further observations with ever-more sensitive telescopes straining to hear an otherworldly message.

In the next year or so, the group plans to broaden its work to include searches based in Puerto Rico at the world's largest antenna, the Arecibo Radio Telescope, 1,000 feet in diameter, which is featured in the movie.

"We do keep champagne on ice," Dreher said after describing the plan. "But I think we'll be too busy to drink it."

Pub Date: 9/04/97

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