Project Phoenix was the world's most sensitive and comprehensive search for extraterrestrial intelligence. It was an effort to detect extraterrestrial civilizations by listening for radio signals that were either being deliberately beamed our way, or were inadvertently transmitted from another planet. Phoenix was the successor to the ambitious NASA SETI program that was cancelled by a budget-conscious Congress in 1993.
Phoenix began observations in February, 1995 using the Parkes 210 foot radio telescope in New South Wales, Australia. This was the largest radio telescope in the Southern Hemisphere. Over a period of sixteen weeks, Phoenix observed about 200 stars that are not visible from northern telescopes.
Following the southern observing campaign, the project turned its attention to northern stars. Appropriately, this phase brought the search back to its roots at the National Radio Astronomy Observatory in Green Bank, West Virginia. The 140 Foot Telescope is only a short distance from the antenna used by Frank Drake in Project Ozma. Project Phoenix operated in Green Bank from September 1996 through April 1998, using the telescope about 50% of the time. During that period, the antenna was the primary instrument at the observatory and so was also used for other radio astronomy projects. Phoenix used the antenna about half of the time.
In August 1998 Project Phoenix moved to Arecibo. Due to the high demand for the world’s largest radio telescope, Phoenix observed in two sessions per year. Each session was three to four weeks long. Observations were conducted primarily at night, from roughly 5:00 PM to 8:00 AM local time at Arecibo. This avoided increased radio interference during the day, and assured that our line of sight to each star was well away from the turbulence of the solar wind.
Unlike many previous searches, Phoenix didn't scan the whole sky. Rather, it scrutinized the vicinities of nearby, sun-like stars. Such stars are most likely to host long-lived planets capable of supporting life. We naturally include stars that are known to have planets. Project Phoenix observed about 800 stars. All are within 200 light-years distance.
Because millions of radio channels were simultaneously monitored by Phoenix, most of the "listening" was done by computers. Nonetheless, astronomers were required to make critical decisions about signals that look intriguing.
Phoenix looked for signals between 1,200 and 3,000 MHz. Signals that are at only one spot on the radio dial (narrow-band signals) are the "signature" of an intelligent transmission. The spectrum searched by Phoenix is broken into very narrow 1 Hz-wide channels, so nearly two billion channels are examined for each target star.
Project Phoenix was sustained entirely through private funding.