SETI Update

by Guillermo Gonzalez

If anyone asks you, "What's up with SETI?" you can give two correct answers, "Plenty" and "Nothing." Plenty of listening continues, but nothing has yet been heard. The acronym SETI became better known when the movie Contact came out in 1997. It stands for the Search for ETI, and ETI stands for ExtraTerrestial Intelligence.

The search has escalated dramatically since Frank Drake's first experiment, Project Ozma, in 1960.⁽¹⁾ Recent major projects include Harvard's META, UC Berkeley's SERENDIP, and the SETI Institute's "Phoenix."^(2-4) Project META lasted five years and is now complete. It covered most of the northern sky with an 8.4 million-channel receiver. The eleven "candidate" signals this project detected were turned over to others for follow up. The SERENDIP and Phoenix projects continue and employ significantly enhanced technology.

Project SERENDIP makes use of the largest single-dish receiver in the world, a 168 million channel system ion Arecibo, Puerto Rico. Though its range is remarkable, the search faces the difficulty of being "piggy-backed" on other experiments. This sharing of the instrument means that the SERENDIP team has no control over target selection.

Project Phoenix boasts certain advantages and distinctives. Its receiver picks up 57 million channels (fewer than SERENDIP), but its "two-site" mode makes it the most fool-proof targeted experiment. A candidate signal picked up at the main site, currently a 140-foot dish at Green Bank, West Virginia, can be quickly targeted by the second site, a 100-foot dish at Woodbury, Georgia, for confimation. The two dishes work in tandem to determine whether the signal is coming from the vicinity of a star or from terrestrial, manmade interference, such as an artificial satellite.

The two radio bands to which Project Phoenix tunes encompass the neutral hydrogen frequency (1420 Mhz, and its 2x harmonic at 2840 Mhz) and the frequency corresponding to the OH molecule (1640 Mhz). Here's the reasoning behind this choice: 1) Hydrogen, the most abundant element in the universe, would seem to make sense as a universal standard. These frequencies minimize radio galactic and atmospheric "noise." 2) Together H and OH make the watrer molecule; so this minimally-noisy section of the radio spectrum is considered a kind of cosmic "water hole," where advanced civilizations, (most likely water-based according to popular notions) might "meet" to talk.

Project Phoenix, while still searching, has found nothing so far. It has followed up, as I mentioned above, the META-detected signals that passed the initial screening criteria to qualify as possible ETI transmissions. Phoenix, with its greater sensitivity and enhanced capability to distinguish man-made interference, has yet to identify a candidate not attributable to that interference. The famous "WOW!" signal detected in 1977 at Ohio State University has been intensely scrutinized, but with no redetection.^(5,6)

Another targeted search deserves special mention. This search focuses on the eight planetary systems outside our own that have been discovered since October 1995. Each of these sites has been searched repeatedly, most recently by Project Phoenix. Since these systems surround nearby stars, we should be able to detect even weak signals, if they are present. To date, our receivers have picked up not so much as a "beep."

SETI research reveals how "reliegious" scientists can be. SETI demands blind faith in the unknown and unseen. Further, it demands rejection of what is known and seen: the abundant evidence for Earth's unique and not-scientifically-predictable capacity to support advanced life. If only these individuals--and the rest of us--would seek God with such patience, persistence, and passion, what a different place this world could be! (See Deut. 4:29)

References

Dr. Gonzalez is an astronomer at the University of Washington.