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Sites under review for telescope that could detect alien TV

July 10, 2006
Special to World Science

Astronomers are working to choose a site for a giant telescope that could read TV or radio signals from alien civilizations.

Artist's concept of collecting dishes for the Square Kilometer Array. The instrument (see www.skatelescope.org)  is so named because it would have radiation-collecting surfaces totalling a square kilometer (about 1/3 square mile.) (Image © Xilostudios)

The instrument, called the Square Kilometer Array or SKA, would be the world’s most powerful radio telescope and would begin operation by 2020, if all goes according to plan.

Radio telescopes are devices that pick up radio waves, a type of light radiation that has less energy than visible light but that can provide valuable information on cosmic structures. 

The SKA, designed to be 50 times as powerful as existing radio telescopes, would be deployed on an array of scientific projects, including studying the formation and evolution of stars and galaxies. 

The telescope, planned since the early 1990s as a collaboration of more than 30 research institutions in 15 countries, would also be capable of looking for distant civilizations—including by picking up their TV or radio transmissions. (World Science, Dec. 29, 2004).

Such a finding “would provide immediate and direct evidence of life elsewhere in the Universe,” project astronomers said in a presentation at a conference of the International Society for Optical Engineering in Orlando, Fla. in May. The telescope would for the first time “enable searches for unintentional emissions or ‘leakage’ at power levels comparable to that of terrestrial TV transmitters.”

Such a search would have distinct limitations, to be sure. 

For one, the instrument might not be able to actually decode the transmissions. Thus we couldn’t necessarily eavesdrop on the latest episode of little green men’s reality shows, if any such thing exists, scientists say. However, we might get a general idea that some sort of TV transmission was occurring, and based on that finding build an even stronger telescope to read it. 

Moreover, any programs we did receive would be several years out of date, because of the delay in light transmission to Earth. 

Scientists also aren’t sure how to recognize such signals, if they do turn up. The hope is that they would feature organized patterns suggestive of intelligence, and not attributable to any known celestial sources.

Only the handful of stars closest to Earth would be within reach of the instrument’s TV-detection capacity, scientists estimate, although it could also detect radar signals at a much greater range. 

Argentina, Australia, China and South Africa have submitted proposals to host the telescope, estimated to cost $1 billion. The number of possible sites will likely be narrowed down further next month, said Yervant Terzian of Cornell University in Ithaca, N.Y., chairman of the consortium’s Site Evaluation Working Group and co-author of the presentation in Orlando.

By the end of August, the project’s steering committee will draw up a short list of acceptable sites that could contain anywhere from one to all four of the proposed locations, Terzian wrote in an email.

A final site decision will take up to two more years, and will also depend on the governments of the countries involved in the project, Terzian added. These governments are also the hoped-for source of SKA funding.

U.S. astronomers have been interested in hosting the telescope but, disappointingly, had to withdraw from the site competition “because of lack of funding to prepare a good proposal,” Terzian wrote in the email.

Planners say the site choice will be based on considerations including construction costs, climate, and political environment, as well as which site offers the best possibilities to configure the telescope.

Researchers have also been refining the telescope design in the past year.  

Like many other radio telescopes, the SKA would be technically not a single telescope but an array of them working in unison. Radio telescopes must be much larger than optical ones because the low energy of radio waves means that many more of them must be picked up to detect a signal. Rather than having mirrors or lenses to gather light, as with traditional telescopes, radio telescopes use parabolic dishes to collect the radiation.

SKA would consist of collecting dishes and other types of radiation-gathering instruments spread over 3,000 km (1,900 miles), although half of the collecting surface would be concentrated within an area 5 km (3 miles) wide. 

The telescope also breaks with tradition in that its most complex aspect will be not the light-gathering equipment, but “the data transmission and central processing facility,” said the presentation by Terzian and Joseph Lazio of the U.S. Naval Research Laboratory.

Other missions of the telescope would be to study planet formation, and to search for signs of the first supermassive black holes and of an exotic type of radiation predicted by Einstein called gravitational waves. The instrument would also serve to study the evolution of the universe from shortly after the fog of the Big Bang explosion, believed to have originated the universe, lifted.

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