THE US Congress cut its funding 14 years ago. Ever since, it has limped by on private generosity, listening to the cosmos for signs of life when time and dollars have permitted.
But now the Search for Extraterrestrial Intelligence (SETI) program is returning in a big way, with the opening of a powerful $A56 million radio telescope in California dedicated solely to listening for ET transmissions.Half-funded by Microsoft co-founder Paul Allen, the Allen Telescope Array — 42 six-metre dishes working in unison to simulate the effect of one "super" dish — opened its first stage this month. When the project is completed in 2010, it will have 350 dishes and be the most sensitive and powerful radio telescope ever built.But the Australian arm of SETI — a useful complement to Allen because of its southern hemisphere location — has stalled through lack of funds.Allen will be used exclusively to listen for signs of ET life.
Researchers have previously had to share other radio telescopes, such as the Parkes dish in NSW or Arecibo in Puerto Rico."It is the first major telescope in the world built specifically for undertaking a search for extraterrestrial intelligence," said Seth Shostak, senior astronomer at the California-based SETI Institute. Dr Shostak told The Sunday Age the first stage of Allen would listen to the billions of star systems in the centre of the galaxy, but then would listen closer to home.
"The longer-term plans are to use Allen for 24/7 observations of individual, nearby stars, working our way out from our nearest stellar neighbours to as far as 1000 light-years in the next two dozen years. The total number of stars that can be observed between now and, say, 2025 is in the order of a million."The first crude SETI search began in 1960, when US astronomer Frank Drake used the Greenbank dish in West Virginia to listen to a couple of nearby stars, Tau Ceti and Epsilon Eridani. SETI's high point was arguably the so-called "Wow" signal of 1977, a 72-second transmission detected by the Big Ear dish in Ohio.
This strong signal bore all the hallmarks of ET origin but follow-up searches — including one by the University of Tasmania's dish in Hobart in 1999 — could not detect the signal.There are more than 100 billion solar systems in the galaxy. Many, if not most, have planets but only a small proportion (if any) will have planets supporting life. Fewer yet will have intelligent life, and even fewer will have the technology to operate radio telescopes.
"(American astronomer) Carl Sagan thought this number (of advanced civilisations) might be millions, and Frank Drake offers a much more conservative number: 10,000 or so," said Dr Shostak. "Taking this range of guesses, and they are guesses, and the expected performance of Allen, one can reckon that even if Drake's lesser number is the truth, we should trip across a signal within two dozen years. However, and as anyone can note, the estimates made by Sagan, Drake, et al could be wide of the mark."
Dr Shostak said Allen could observe "roughly two-thirds" of the galaxy. Australian SETI, which can cover the rest, "would be a welcome complement," he said.
"Every SETI experiment is different and the Australian effort, using the Parkes radio telescope, was a top-notch experiment and the only major experiment at the time being conducted outside the US. In science, it always pays to have multiple approaches, using different equipment and different strategies. It's a horse race and would be a lot more interesting with another horse or two."
But the project scientist with SETI Australia, Ain de Horta, said lack of government support had forced local SETI to a halt. "The last time we did any serious analysis was two years ago, 2005," he said. Mr de Horta said there was still unanalysed data from the last Australian SETI effort, Southern SERENDIP, which began in 1998 using Parkes.
by www.thesupernaturalworld.co.uk
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