SETI (redirected from Exterrestrial intelligence)

SETI (sĕt`ē) [Search for ExtraTerrestrial Intelligence], name given to a series of independent programs to detect radio signals from civilizations beyond the solar system. Modern SETI efforts can be dated from 1959 when Cornell Univ. physicists Giuseppi Cocconi and Philip Morrison pointed out the potential for using microwave radio signals to communicate with extraterrestrial civilizations. They suggested that a frequency of 1420 MHz be utilized as a communication channel since that corresponded to the signal emitted by neutral hydrogen, the most abundant element in the universe; that frequency, by international agreement, is now prohibited in all radio transmissions everywhere on and off the earth.

In 1960 the first such program, Project Ozma, led by American astronomer Frank Drake at the National Radio Astronomy Observatory in Green Bank, W.Va., focused on the nearby stars Epsilon Eridani and Tau Ceti. Since then some 50 searches, most of limited duration and concentrating on stars similar to the sun, have been conducted without success. In 1992 the High Resolution Microwave Survey (HRMS) was initiated. Using radio telescopes around the world in a planned ten-year search, HRMS envisioned a two-pronged approach. One group was to focus on solar-type stars within 100 light-years of Earth; the other was to conduct an all-sky survey. HRMS was halted by a funding cutback in 1993, but privately raised funds were used by the SETI Institute beginning in 1995 to conduct a search of nearby solar-type stars. Project Phoenix, as it is now called, monitors only microwave frequencies because there are few natural sources of emissions in that range and researchers hope that extraterrestrials would recognize that range as a quiet region of the electromagnetic spectrum suited to sending a message.

In addition to the listening efforts of the radio astronomers, other forms of contact have been attempted. Various coded messages have been broadcast in the hope that an extraterrestrial civilization might also have a SETI program. Gambling on a chance encounter with an extraterrestrial civilization, the U.S. space probes Pioneer 10 and 11 each carry an engraved plaque with a message from the earth, and Voyager 1 and 2 each have a recorded message of words and music. All four of these space probes have left the solar system and will travel in interstellar space indefinitely.

Bibliography

See also E. Ashpole, The Search for Extraterrestrial Intelligence (1990); D. Swift, SETI Pioneers: Scientists Talk about Their Search for Extraterrestrial Life (1990); F. Drake and D. Sobel, Is Anyone Out There? The Scientific Search for Extraterrestrial Intelligence (1992).

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SETI

 in full search for extraterrestrial intelligence

Ongoing effort to seek intelligent extraterrestrial life. SETI focuses on receiving and analyzing signals from space, particularly in the radio and visible-light regions of the electromagnetic spectrum, looking for nonrandom patterns likely to have been sent either deliberately or inadvertently by technologically advanced beings. The first modern SETI search was Project Ozma (1960), which made use of a radio telescope in Green Bank, W.Va. SETI approaches include targeted searches, which typically concentrate on groups of nearby sunlike stars, and systematic surveys covering all directions. The value of SETI efforts has been controversial; programs initiated by NASA in the 1970s were terminated by congressional action in 1993. Subsequently, SETI researchers organized privately funded programs—e.g., the targeted-search Project Phoenix in the U.S. and the survey-type SERENDIP projects in the U.S. and Australia. See also Drake equation.

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SETI

(Search for ExtraTerrestrial Intelligence) A huge grid computing project on the Internet that takes advantage of unused processing time in users' computers to analyze radio telescope data. The purpose of SETI@home, which is administered by the University of California at Berkeley, is to pick up communications from other planets. If narrow-bandwidth radio signals were to be detected, scientists maintain that these unnaturally occurring communications would be evidence of extraterrestrial sources.

Get Involved!
You can participate by downloading a screen saver that converts idle time into computations. Data are saved every couple of minutes and sent back to the SETI Web site at periodic intervals. Initiated in 1999, millions of enthusiastic users have since generated well over a billion results. For more information, visit www.setiathome.ssl.berkeley.edu. See grid computing.

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SETI [′sed·ē]

(astronomy)

search for extraterrestrial intelligence