The search for alien life has begun

November 14th, 2007 - 2:06 am ICT by admin  
The first phase of the Allen Telescope Array, which is being built near Hat Creek, California, US, has begun functioning with 42 radio antennas.

Upon completion, the ATA, named in honour of Microsoft co-founder Paul Allen, who donated seed money for the project, will have 350 dishes, each about six metres wide.

Until now, the SETI project relied on time borrowed from instruments like the Arecibo radio telescope in Puerto Rico, and has had little control over the extent and nature of the observations.

On the other hand, the Allen Telescope Array will specifically allow SETI astronomers to survey the skies for signs of alien intelligence 24 hours a day, seven days a week.

“This will be the first time that we can actually have a telescope [with] the characteristics we can determine,” said Jill Tarter, director of the Center for SETI Research in Mountain View, California.

The ATA will look for radio signals in frequencies ranging from about 1 to 10 gigahertz, a range mostly free of interference from other radio sources, such as emission from electrons spiralling around galactic magnetic fields.

“The only source of noise is the cosmic microwave background,” said Tarter, referring to remnant radiation from the big bang, whose signal has been well studied.

But scanning the sky for aliens will only be part of ATA’s duties. The telescope’s large field of view will make it well suited for conducting large-scale surveys of the sky.

While observing at the frequency that hydrogen atoms emit radiation, it will be able to image a circle on the sky as wide as about five Full moons.

Tarter said, practically this made the ATA the radio analogue of the Sloan Digital Sky Survey, which uses a wide-field 2.5-metre telescope in New Mexico, US, to image large swathes of the sky at visible wavelengths and create 3D maps of millions of galaxies.

“The ATA will do for radio astronomy what Sloan has done for optical astronomy,” he said, adding that the telescope will conduct the surveys while simultaneously searching for SETI signals from a few stars in the same regions of the sky.

“The telescope is built so that both projects can go on simultaneously,” New Scientist quoted William Welch, a former professor at the University of California in Berkeley who designed the ATA’s receiver electronics, as saying. (ANI)

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