Is Anyone Out There?
Building a Giant "Radio Ear" to Intercept Intelligent Signals from Space
By Robert Sanders, Public Affairs
The Berkeley campus and the Mountain View-based SETI Institute have teamed up to design and build an array of 500 to 1,000 radio telescopes whose primary task will be to seek out signals from civilizations elsewhere in our galaxy.
Rather than construct one large and expensive radio telescope or even an array of many large, custom-built telescopes, the Berkeley/SETI Institute team will explore the use of many inexpensive antennas similar to those used for backyard TV reception. By electronically coupling many dishes together, a large "radio ear" can be constructed at a fraction of the cost of more conventional approaches. The project is estimated to cost less than $25 million, and could be completed by 2004.
"This represents a paradigm shift in the design and construction of radio telescopes," said Jill Tarter, science team leader for the Institute's current SETI program. (SETI stands for Search for Extraterrestrial Intelligence). "We hope to demonstrate that a premium instrument need not have a premium price."
Berkeley researchers emphasize, though, that the novel array will be spectacular for radio astronomy, too. Because of its unique construction, the telescope could be used simultaneously for SETI and other radio astronomy observations.
"The instrument we want to build will have unique capabilities for observing objects from the solar system to the edge of the universe," said Professor Leo Blitz, director of the Berkeley Radio Astronomy Lab. "Our goal is nothing short of standing the way radio astronomy has been done up to now on its head."
The array will eventually comprise a total collecting area of one hectare (2.47 acres), hence the project's current name, the One Hectare Telescope, or 1hT. The 1hT will be among the world's largest radio telescopes and the largest observing facility devoted substantially to SETI. SETI observations require not only a large collecting area -- to find the weak signals expected from a transmitter many light years away -- but also highly sophisticated digital receivers to scrutinize millions of radio channels.
Currently SETI scientists, at best, are able to scan only a few hundred star systems per year. The 1hT could expand this number at least tenfold. In the Milky Way Galaxy alone, there are an estimated 400 billion stars.
"Berkeley has one of the world's premier radio astronomy programs, along with first-rate programs in engineering and computer science, " said Tarter. "Together, we can design and build an instrument that will have no peer for this type of work."
The first goal will be to build a prototype composed of perhaps a dozen small radio dishes at Berkeley's Hat Creek Observatory, located near Mt. Lassen in northern California. The Hat Creek Observatory is the site of a ten-telescope array now operated by campus. Once the 1hT concept has been proven and the electronics are working, the team would embark on the construction of an array of up to 1,000 telescopes, probably also at Hat Creek.
The design concept of the 1hT should significantly reduce the cost of construction, according to Berkeley and SETI Institute researchers. Unlike conventional radio telescopes, the 1hT is scalable. By adding new dishes to the array, it could be made larger at relatively low cost. And if an individual 1hT dish is damaged, it can be replaced quickly and cheaply.
Berkeley's lead astronomer on the 1hT project, Professor of Astronomy William "Jack" Welch, plans to support a targeted SETI search in addition to conducting observations of star-forming regions. Welch said that the 1hT team will begin the search with 1,000 nearby sun-like stars and gradually move outward to encompass 100,000 then one million candidate stars in our galaxy. The team will search for strong signals at a single frequency -- like radar or radio broadcasts from Earth -- as well as pulsed signals that repeat.