Project Phoenix will immediately test candidate signals. Scientific evidence shows that life arose on the Earth relatively quickly, suggesting that life will occur on similar planets orbiting Sun-like stars. SETI tests this hypothesis by searching for specific technological manifestations of intelligent life. To accomplish these activities on Earth, our technology uses electromagnetic waves such as light, radio, and infrared. To be detectable over interstellar distances, such signals must not be absorbed by interstellar plasma.
Radio waves travel through space with the least absorption or distortion.
Most SETI searches concentrate on microwaves, radio waves in the frequency range from 1,000 MHz to 10,000 MHz. Radio waves emitted by natural astronomical objects are spread over bands of frequencies wider than a few hundred Hertz, are seldom polarized, and are not constant in phase. Artificial signals, produced by a transmitter and antenna, are often confined to a narrow range of frequencies, are highly polarized, and have the peaks of the waves in phase. Artificial signals may contain encoded information, while natural signals do not. With our best rocket technology a flight to the Sun's nearest neighbor, Alpha Centauri, only 4 light years away, would take about 70,000 years.