e-Pulsar - Apr

e-Pulsar Apr - May 99

Astronomical Feature of the Month
SETI

Arecibo message While interest in the question of extraterrestrial life is at least as old as historical civilizations, the modern SETI era can be defined as beginning in 1959. Cornell physicists Giuseppi Cocconi and Philip Morrison published an article pointing out the potential for using microwaves to communicate between the stars. A young radio astronomer, Frank Drake, had independently reached the same conclusion, and in the spring of 1960 conducted the first microwave radio search for signals from other solar systems. For two months Drake aimed an 85-foot West Virginia antenna in the direction of two nearby Sun-like stars. His single-channel receiver was tuned to the "magic" frequency of the 21 cm (1,420 MHz) line of neutral hydrogen, a spot on the radio dial also favored by Cocconi and Morrison because of its astronomical significance. While he didn't detect any signal of extraterrestrial origin, Drake's Project Ozma spurred the interest of others in the astronomical community, most immediately the Soviets. In the 1960's, the Soviet Union dominated SETI, and frequently adopted bold strategies. Rather than searching the vicinities of nearby stars, the Soviets used nearly-omnidirectional antennas to observe large chunks of sky, counting on the existence of at least a few very advanced civilizations capable of radiating enormous amounts of transmitter power. During the 1970's, many radio astronomers conducted searches. Some of the efforts, employing improved technology, have continued to the present time. Foremost among these are the Planetary Society's Project META, the University of California's SERENDIP project, and a long-standing observing program at Ohio State University.

SETI programs were established at NASA's Ames Research Center and at the Jet Propulsion Laboratory (JPL) using a dual-mode strategy for a large-scale project. Ames would examine 1,000 Sun-like stars in a Targeted Search, JPL would systematically sweep all directions in a Sky Survey. In 1988, NASA Headquarters formally adopted this strategy and funded the program. Four years later observations began. Within a year, Congress terminated funding.

With NASA no longer involved, both researchers and interested members of the public saw a diminished chance to answer the profound questions addressed by SETI. Private funding has taken up the challenge.

Project Phoenix will concentrate efforts on that component of the NASA SETI project known as the Targeted Search. Its strategy is to carefully examine the regions around 1,000 nearby Sun-like stars. Project Phoenix is orders of magnitude more comprehensive than any experiment yet performed.