If E.T. calls, many 'ears' will be listening

By Carrie Peyton Dahlberg

Published: May 13, 2008

HAT CREEK, Calif. — Dotting a rocky plain north of Mount Lassen, 42 radio antennae are cocked like ears toward the sky, being readied for an expanded hunt for life beyond Earth.

The Allen Telescope Array is slowly coming together as the new listening post for SETI, the Search for Extraterrestrial Intelligence.

At the Hat Creek Radio Observatory, silver-snouted antennas soon will take up the quest for a technological culture that is audacious or lonely or hopeful enough to deliberately beam a signal into the beyond.

It would be a sort of cosmic "Hey, is anybody out there?”

This summer, when the alien-hunting function of the telescope array is expected to start, only a powerfully blasted or very close message would get through.

The array is missing 308 of the 350 antennae that the SETI Institute once hoped to have installed by this year. And equipment still is arriving to enable SETI operators to simultaneously focus on key stars while the antennae also are used in other research.

The San Francisco Bay Area-based SETI Institute is dedicated to understanding the origins and prevalence of life throughout the universe.

The scrappy nonprofit, which decorates some antennae with donor names and advertises an "adopt a scientist” program on its Web site, is scrambling for $35 million to $40 million needed to finish the array.

Even then, "finish” isn't quite the right word. Beyond 350 antennae, some researchers speak wistfully of what they might do with 500.

"There's always hope,” said Peter Backus, manager of the institute's observational programs.

SETI runs on hope, fueled by yearning for the breathtaking long shot of alien contact. But its telescope is grounded in pragmatism.

The institute has teamed with the University of California-Berkeley's Radio Astronomy Laboratory to create a radio telescope that already has begun making wide, rapid surveys of gases in the sky.

"They're doing a lot of things no one has done before,” said Chris Carilli, a radio astronomer with the National Radio Astronomy Observatory in New Mexico, who is involved in telescope development in Chile.

"Even with 42 antennas, it will be an impressive survey instrument … really a uniquely powerful instrument,” Carilli said.

The Allen array relies on multiple, small antennas to create a bigger picture. The complex electronic "back end” of the telescope can be turned into four different instruments, all using the same antennae for different purposes.

Only one of those instruments is devoted to the SETI search. Others are aimed at mapping galaxies, probing how stars are formed and capturing the distant drama of black holes feeding and supernovas exploding.

Unlike optical telescopes, which measure stars and other objects in the visible spectrum, radio telescopes tune into the wavelengths emitted by solid objects, gases and electrons whirling through space.

The Allen array can observe at a wide range of radio wave frequencies, producing detailed inventories across broad swaths of sky.

"We generate an amazing amount of data,” said Rick Forster, resident astronomer at the remote observatory, which lies amid sage, deer brush and scattered pines southeast of Burney in eastern Shasta County, Calif.

Forster, who will turn 60 this month, has spent his career in conventional radio astronomy, examining gases, galaxies and other structures to help understand how the universe is put together. He lives for that moment when an experiment he designed has been performed and he's facing a mountain of data, about to plunge in, seeking conclusions.

"It's the thrill of the hunt,” Forster said. "You know there's an Easter egg in there, and you have to work for it. … I just love it.”

Since the Allen array's first three antennae went up in 2005, much of Forster's time has been devoted to questions involved in engineering, calibrating and testing.

Among astronomers, the telescope's progress is being followed closely because its solutions to technical problems could be incorporated into the next generation of much larger radio telescopes.

Some of the issues have been as complex as how to squeeze the most performance out of hardware and software that will focus SETI's search.

Other problems have been as down-to-earth as to how to dim overly bright antennae.

The radio dishes don't need to gleam, and astronomers had promised the Forest Service that they wouldn't, so that reflected sunlight would not hamper the wilderness experience for hikers on the Pacific Crest Trail just three miles east of the observatory.

When the equipment showed up shinier than expected, technicians began a tedious process of disassembling each antenna, blasting the curved dish with baking soda to dull the surface, then putting its delicate innards back in place. The process left the ground below some antennae dusted white with baking soda.

It has cost about $50 million so far to design, create and install the 42 antennae that make up the first phase of the Allen Telescope Array, named for Microsoft co-founder Paul Allen, whose foundation donated $25 million to the effort.

Other funds have come from private donors, University of California-Berkeley and the National Science Foundation.

Because so much expensive design and development work has been done, the remaining 308 antennae will be much cheaper, probably coming in under $40 million, said Jill Tarter, SETI director.

There is no firm timetable for completion, because that money is not in hand.

"If I had a check today, it would be two years,” Tarter said.

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