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A panoramic view of the 42-antenna Allen Telescope Array in Hat Creek, Calif. The array was dedicated Oct. 11. (UC Berkeley photo)
 

Huzzahs at Hat Creek: Hip-hip array!
The dishes of the Allen Telescope Array will play a major role in the ongoing search for extraterrestrial life

| 17 October 2007

At a ceremony in a remote corner of Northern California last week, a new-concept radio telescope devoted equally to galactic astronomy and the search for extraterrestrial intelligence was dedicated by the Berkeley campus and the SETI Institute.

Located in an arid valley near the town of Hat Creek, just north of Lassen Volcanic National Park, the first 42 of a planned 350 radio dishes of the Allen Telescope Array (ATA) recently started collecting scientific data from the far reaches of the universe, opening a new era of radio astronomy research. The ATA also is the largest telescope devoted to the search for extraterrestrial intelligence (SETI).

"This is a great day for the science of radio astronomy and the study of the cosmos," said Leo Blitz, a Berkeley professor of astronomy and director of the university's Radio Astronomy Laboratory, which is building the ATA with the SETI Institute of Mountain View. "Thanks to a unique intersection between the best in science; advanced, innovative technology; and bold philanthropy, many secrets of the universe are a little closer to being revealed."

The radio-telescope array will expand search capabilities for intelligent civilizations beyond Earth and provide a better understanding of exploding stars (supernovas), the massive black holes at the cores of distant galaxies, and new, exotic astronomical objects that are predicted but not yet observed.


The ATA's 20-foot-diameter antennas are each mounted on pivots that allow them to view the entire sky above Northern California. (Seth Shostak, SETI Institute)
 

Based on the idea that a large number of small radio antennas are cheaper to build than a small number of large dishes, the ATA breaks new ground as the first panchromatic, wide-angle, snapshot radio camera ever built, and is the most effective tool to create radio images of a vast area of the sky ever placed in the hands of researchers.

Paul Allen, Microsoft co-founder and philanthropist whose foundation donated seed money that started the project in 2001, joined representatives of Berkeley and the SETI Institute to launch the array.

"This project represents a potential breakthrough in building large arrays of radio telescopes that are extremely cost-effective," said Allen, the primary funder of the ATA. "As now deployed, and with plenty of room for growth in the future, the telescope can fulfill a multitude of uses, including broad radio-sky surveys and the search for evidence of extraterrestrial technology. I'm pleased to be able to contribute to such an important advancement and help build on the work this new telescope will do in the future. My hat is off to the team that worked so hard these last seven years to accomplish this significant milestone."

Speedier sky surveys

Every object in space emits radio waves that can be captured and studied. From analysis of these signals, radio astronomers can create a picture of astronomical objects and events at great distances, revealing detail not discernible by telescopes operating at other wavelengths. Unlike existing radio telescopes, the ATA can image a large piece of the sky at once, enabling much speedier surveys of the heavens than currently possible.

The telescope's first test images, released last week from data gathered by the 42 ATA telescopes, include a radio map of the nearby Andromeda Galaxy (M31) and the Pinwheel Galaxy (M33).

"We welcome the Allen Telescope Array to the ranks of cutting-edge instruments seeking to advance the frontiers of astronomical knowledge, and congratulate the team whose vision, innovation, and hard work have made it a reality," said Dr. Fred Lo, director of the National Radio Astronomy Observatory. "The ATA will play an important role, both technologically and scientifically, in the exciting future of 21st-century astrophysics."

Beyond its speed and ability to both collect and analyze data, the ATA is also the first centimeter-wavelength radio telescope with the ability to multi-task. While making innovative observations for radio astronomy, it can simultaneously interrogate solar-type stars for artificially produced signals that would reveal the presence of extraterrestrial intelligence.

"For SETI, the ATA's technical capabilities exponentially increase our ability to search for intelligent signals, and may lead to the discovery of thinking beings elsewhere in the universe," said astronomer Seth Shostak of the SETI Institute.

This new capability increases many-fold the time astronomers can devote to large-scale surveys of the stars, as well as expands the radio-frequency band over which they can search. For SETI, in particular, this means that over the next two-dozen years the ATA will get 1,000 times more data than has been accumulated in the past 45 years.

Comparing the search for intelligent civilizations in the Milky Way Galaxy to the search for the proverbial "needle in a haystack," Shostak noted that "we don't know how many needles are in the galactic haystack of 400 billion stars, but I think we will find (signals from intelligent civilizations) by 2025."

"Over the next five years we will enter an era in which we will be discovering Earth-like planets, and ATA offers the opportunity to stare for hours or weeks at these planets in search of intelligent signals," said Berkeley's premier planet-hunter, astronomy professor Geoffrey Marcy. "I expect the telescope to be fully online when we find that first Earth-like planet around a Sun-like star, so we can point the ATA at it and listen."

The ATA uses mass-produced, 20-foot-diameter radio dishes and commercial telecommunications technologies combined with an innovative receiver design and state-of-the-art technology for digital-signal processing. Working together, these small dishes create a telescope with a wide field of view ideally suited to rapidly surveying the sky.

The layout of the 42 dishes was created by a computer model and is optimized to provide high-quality radio imagery of the sky. The ATA can also filter out noise from manmade interference that for many radio telescopes would render much of the data unusable. The array can be easily upgraded as new advances in computer or telecommunications technology become available. 

Both Berkeley and the SETI Institute are engaging in additional fundraising efforts to complete the 350-dish array. Capitalizing on constant advancements in computer technology, the ATA will be manufactured at a fraction of the cost of traditional instruments. The ATA team is prepared to install more dishes as additional funding is secured.

The total cost of the project to date, including research, development, and construction costs for the array and the necessary radio astronomy and SETI signal detectors, is $50 million. The first phase of the project was funded through grants from the Paul G. Allen Family Foundation totaling $25 million. UC Berkeley, the SETI Institute, the National Science Foundation, Xilinx, Nathan Myhrvold, Greg Papadopoulos, and other corporations and individual donors contributed additional funding.