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Eavesdropping on extraterrestrial intelligence

Experimental array will enhance future telescope's listening power 100-fold

By Diane Ainsworth, Public Affairs
Posted May 3, 2000

With the push of a button, a small array of seven satellite dishes, about the size of your backyard variety but capable of amplifying the natural noise of the universe by 100-fold, swept skyward April 19 to begin listening to the stars.

The 3.6-meter-diameter (12-foot) mesh dishes, tucked away in a redwood forest 12 miles northeast of campus, comprise the first testbed of a new kind of radio telescope. Known as the One Hectare Telescope, or 1hT, for its total collecting area of one hectare (2.47 acres), the array is the precursor to the world's most powerful instrument for detecting artificial signals from intelligent life elsewhere in the Milky Way galaxy.

"This is the first step, a giant step, in a new search for extraterrestrial intelligence," said Frank Drake, president of the private SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, Calif., and father of the first, one-channel radio telescope survey four decades ago. "Today's telescopes are 10 times more sensitive than the telescopes we had 40 years ago. We can tune into 56 million channels at once with a receiving power that is 100 trillion times greater than the first telescopes."

A joint project of the SETI Institute and Berkeley, 1hT will be a world-class telescope array costing an estimated $25 million, about one-fifth the cost of building a comparable radio telescope using conventional methods. Within five years, as many as 1,000 of these metal mushrooms will be splayed across 2 1/2 acres of UC's Hat Creek Observatory, located about 290 miles northeast of San Francisco.

1hT will serve as a testing ground for a telescope array capable of monitoring every radio frequency from one to 12 gigahertz in the microwave region of the galaxy. This is a relatively noise-free portion of the electromagnetic spectrum in which all celestial objects reside. Because the heavens are relatively "quiet" in this frequency range, astronomers will be able to detect an artificial signal emanating across billions of miles of space without interference from naturally occurring cosmic static.

At least 400 billion stars emit radiation in the Milky Way galaxy. Within range of current detection instruments are at least 10 billion other galaxies, many of which are larger than the Milky Way. Beyond them may lie a gigantic number of galactic islands -- perhaps an infinite number -- and corresponding to that, an infinity of suns.

Berkeley planet-hunter Geoff Marcy, professor of astronomy, has discovered more than 25 planets orbiting suns. It is now estimated that at least 3 percent of the 400 billion stars in the galaxy host planets. Could there be intelligent life in other solar systems? True SETI believers and many astronomers would argue that it's a statistical reality; intuition alone suggests that in such a vast firmament, many hearts would beat.

Radio astronomers and SETI searchers are ecstatic about the new prototype telescope array, as it will allow them to conduct conventional radio astronomy investigations while others search for signs of intelligent transmissions at the same time.

No longer will SETI researchers have to wait for access to the world's largest telescopes, located in Puerto Rico and Socorro, N.M., to conduct their sky surveys. The "marriage" of these two disciplines represents an astronomical breakthrough made possible with the advent of inexpensive electronics, affordable supercomputers and digital signal-processing technology.

"We want to build an instrument that uses hundreds of commercial satellite dishes and design one of the largest radio telescopes in the world,'' said Leo Blitz, director of the Berkeley Radio Astronomy Laboratory. "1hT is the engagement ring of that marriage."

Using the seven dishes, scientists will be able to learn more about the hardware and operating system necessary to power such a telescope array. They are keen to develop advanced signal-processing methods to eliminate interference, especially from telecommunications satellites.

At the same time, according to John Dreher, 1hT project manager, they will study the feasibility of using those same telecommunications satellites, which make up NASA's Global Positioning System, to calibrate the array and improve the performance of the full 1hT.

In the first three years of prototype operations, engineers will analyze the use of inexpensive drives and mounts to aim the dishes, Dreher said. Early versions of a new digital device known as a "beamformer" -- which will make sky surveys 10 times faster and allow astronomers to observe a dozen stars simultaneously -- will also be under investigation.

Jill Tarter, director of SETI research at the institute, concurred. "We can't wait to get started," she said. "The rapid prototype array will help us figure out how to combine the output of an array and remove all of the interference from commercial satellites in real time."

The array, which will be comparable in its collecting area to New Mexico's Very Large Array, will begin partial operations in 2004 and be fully functional sometime the following year.



May 3 - 9, 2000 (Volume 28, Number 32)
Copyright 2000, The Regents of the University of California.
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