An ambitious project that could one day revolutionize the search for extraterrestrial intelligence is approaching an early but critical milestone -- the completion of an array of eight small radio antennas that will simultaneously scan every area of the sky with striking precision.

Astronomers at Ohio State University say that within months, they will complete the eight-antenna array, and reach a major step in a plan to combine the sky-searching power of 64 radio antennas.

The project is named after Argus, the 100-eyed giant in Greek mythology.

The current state of computer technology limits the project for the foreseeable future but the prototype array could demonstrate the feasibility of a project that could not only transform the search for extraterrestrial intelligence, or SETI, but the field of radio astronomy itself.

Argus under construction.

Radio telescopes work by scanning the sky for signals at various frequencies in the radio spectrum, similar to tuning a personal radio to different music stations. Large dishes, like Arecibo in Puerto Rico, can pick up even very weak signals coming from a specific point in the sky. The dishes are designed to change their angle so that they can search different parts of the sky.

In the Argus project, however, astronomers are using radio antennas that are sensitive to even weak signals from the entire sky. By placing many of these antennas near each other and linking them to a central computer system, the astronomers can actually combine the data to create detailed radio images that no single antennae could produce.

Argus' s data archive, then, would hold detailed information about radio signals coming from any place in the sky.

In theory, relatively inexpensive omnidirectional antennas could be added to an antenna array like Argus's until it is the most powerful radio telescope in the world. But even if Argus, with 64 antennas, were to search a fraction of the frequencies in the sky, it would require a computer as powerful as 2000 Pentium PCs to function, according to Dr. Steven W. Ellingson, a researcher at Ohio State's ElectroScience Lab. To search the entire range of frequencies, Argus would require the computing power of one million PCs.

The eight-antenna array will use 21 computers, linked together, to conduct a limited search, Ellingson said.

An omnidirectional antennae, like that used in Argus

Columbus, Ohio, the location of Argus, seems like a strange place to search for alien signals, especially since cities are bombarded with artificial radio waves that interfere with the signals emanating from celestial sources. But Ellingson says that Columbus is an ideal place for a prototype array, because he will learn how to program the system to weed out the bad signals. Even weak signals, he said, are "devastating to radio astronomy."