LOL.... Hi, Tom!

I heard all you said up there.

There was a wonderful article about Kent Cullers, SETI and Project Phoenix in last month's (December) issue of Astronomy Magazine.

[Kent Cullers attended graduate school at the University of California at Berkely. His 1980 doctoral thesis analyzed a layer of ionized gas, or plasma, in Earth's upper atmospherre by studying changes in the strength and frequency distribution of radar waves. Cullers developed computer algorithms to pull the weak backscattered radar signals out from the general cosmic noise.

When Cullers listens to the night sky, he says it mostly sounds like white noise - what you hear when you're not tuned to a radio station. But when he listens to a maser (a type of amplified microwave emisison, analogous to a laser), he discerns different sounds, as if the noise changes its character. His trained ear picks up subtle, narrow frequency components over the noise in much the same way his computer algorithms find alien signals. In effect, his algorithms are a way of teaching computers to do the same thing the human ear does, but with much greater sensitivity. "The computer detects signals that are about a thousand times weaker than what the human ear detects," he says.

Project Phoenix began searching for signals coming from sun-like stars within 200 light years of Earth. Phoenix focuses on the microwave region (between 1,000 and 3,000 megahertz) of the radio spectrum, where the cosmic background is the quietest and where a weak alien signal is most likely to be heard. The system's computers simultaneously analyze 28 million one-Hertz-wide channels (eventually covering all two billion channels in the microwave window for each star) while looking for narrow, artificial signals.

The Project Phoenix team uses the 1,000 foot (305 meter) radio telescope at Arecibo, Puerto Rico, for two three-week observing sessions each year. Cullers occasioanlly travels there during the observations to get a feel for how signals from terrestrial sources interfere with the search. The amount and kind of interference changes each year, and his algorithms must account for it. "Rejection of unwanted signals is probably at least as big a part of SETI as detection of the desirable," he says. ]

We wouldn't be where we are (listening), if we hadn't tried.

Marcia