SETI

SETI (pronounced {{IPA|}}, to rhyme with "Betty") stands for Search for Extra-Terrestrial Intelligence.

Radio SETI experiments

Early work

In 1960, Cornell University astronomer Frank Drake performed the first modern SETI experiment, named "Project Ozma", after the Queen of Oz in L. Frank Baum's fantasy books. Drake used a 25-meter-diameter radio telescope at Green Bank, West Virginia, to examine the stars Tau Ceti and Epsilon Eridani near the 1.420 gigahertz marker frequency.

Related Topics:
1960 - Cornell University - Frank Drake - Project Ozma - Queen of Oz - L. Frank Baum - Green Bank, West Virginia - Tau Ceti - Epsilon Eridani

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A 400 kilohertz band was scanned around the marker frequency, using a single-channel receiver with a bandwidth of 100 hertz.

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The information was stored on tape for off-line analysis. Nothing of great interest was found.

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The first SETI conference took place at Green Bank in 1961. The Soviets took a strong interest in SETI during the 1960s and performed a number of searches with omnidirectional antennas in the hope of picking up powerful radio signals beginning in 1964.

Related Topics:
1960s - Omnidirectional antenna

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TV-Host/American astronomer Carl Sagan and Soviet astronomer Iosif Shklovskii together wrote the pioneering book in the field, Intelligent Life in the Universe which appeared in 1966.

Related Topics:
Carl Sagan - Iosif Shklovskii - 1966

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In 1971, the U.S. National Aeronautics and Space Administration (NASA) funded a SETI study that involved Drake, Bernard Oliver of Hewlett-Packard Corporation, and others. The report that resulted proposed the construction of an Earth-based radio telescope array with 1,500 dishes, known as "Project Cyclops". The price tag for the Cyclops array was $10 billion USD, and, not surprisingly, Cyclops was not built.

Related Topics:
1971 - National Aeronautics and Space Administration - Bernard Oliver - Hewlett-Packard - Project Cyclops

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Arecibo message

In 1974, a largely symbolic attempt was made to send a message to other worlds. To celebrate a substantial upgrading of the 305 metre Arecibo Radio Telescope in Puerto Rico, a coded message of 1,679 bits was transmitted towards the Globular Cluster M13, some 25,000 light years away.

Related Topics:
1974 - Arecibo Radio Telescope - Puerto Rico - Coded message - Globular Cluster M13

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The pattern of 0s and 1s contained in the message defined a 23 × 73 grid which when plotted revealed some data about our location in the Solar System, a stylised figure of a human being, chemical formulae and an outline of the radio telescope itself. The 23 by 73 grid was chosen because both 23 and 73 are prime numbers and it was thought that this could aid any hypothetical alien listener to recognize the grid representation.

Related Topics:
Solar System - Prime number

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Given the limitations of the speed of light, no reply would be possible for 50,000 years and hence has been dismissed by some as a publicity stunt. A controversy arose because the transmission raised the serious question of whether a small group should be allowed to speak for Earth.

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SERENDIP, Sentinel, META, and BETA

In 1979 the University of California, Berkeley launched a SETI project named "Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations (SERENDIP)" http://seti.ssl.berkeley.edu/serendip/. In 1980, Carl Sagan, Bruce Murray, and Louis Friedman founded the U.S. Planetary Society, partly as a vehicle for SETI studies.

Related Topics:
1979 - University of California, Berkeley - Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations - 1980 - Carl Sagan - Bruce Murray - Louis Friedman - Planetary Society

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In the early 1980s, Harvard University physicist Paul Horowitz took the next step and proposed the design of a spectrum analyzer specifically intended to search for SETI transmissions. Traditional desktop spectrum analyzers were of little usefulness for this job, as they sampled frequencies using banks of analog filters and so were restricted in the number of channels they could acquire. However, modern integrated-circuit digital signal processing (DSP) technology could be used to build autocorrelation receivers to check far more channels. This work led in 1981 to a portable spectrum analyzer named "Suitcase SETI" that had a capacity of 131,000 narrowband channels. After field tests that lasted into 1982, Suitcase SETI was put into use in 1983 with the 25-meter Harvard/Smithsonian radio telescope at Harvard, Massachusetts. This project was named "Sentinel", and continued into 1985.

Related Topics:
Harvard University - Paul Horowitz - Digital signal processing - Autocorrelation - 1981 - Harvard, Massachusetts

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Even 131,000 channels weren't enough to search the sky in detail at any fast rate, and so Suitcase SETI was followed in 1985 by Project "META", for "Megachannel Extra-Terrestrial Array". The META spectrum analyzer had a capacity of 8 million channels and a channel resolution of 0.5 hertz. The project was led by Horowitz with the help of the Planetary Society, and was partly funded by moviemaker Steven Spielberg. A second such effort, META II, was begun in Argentina in 1990 to search the southern sky. META II is still in operation, after an equipment upgrade in 1996. Also in 1985, Ohio State University began their own SETI program, named Project "Big Ear", which later received Planetary Society funding. The next year, in 1986, UC Berkeley initiated their second SETI effort, SERENDIP II, and has continued with two more SERENDIP efforts to the present day.

Related Topics:
1985 - 1990 - 1996 - Ohio State University

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The Planetary Society is now pursuing a follow-on to the META project named "BETA", for "Billion-Channel Extraterrestrial Array".

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This is a dedicated DSP box with 200 processors and 3 gigabytes of RAM. BETA is about a trillion times more powerful than the signal processing equipment used in Project Ozma. BETA actually scans only 250 million channels, with a range of 0.5 hertz per channel.

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It scans through the microwave range from 1.400 to 1.720 gigahertz in eight hops, with two seconds of observation in each hop.

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MOP and Project Phoenix

In 1992, the U.S. government finally funded an operational SETI program, in the form of the NASA "Microwave Observing Program (MOP)". MOP was planned as a long-term effort, performing a "Targeted Search" of 800 specific nearby stars, along with a general "Sky Survey" to scan the sky. MOP was to be performed by radio dishes associated with the NASA Deep Space Network, as well as a 43-meter dish at Green Bank and the big Arecibo dish. The signals were to be analyzed by spectrum analyzers, each with a capacity of 15 million channels. These spectrum analyzers could be ganged to obtain greater capacity. Those used in the Targeted Search had a bandwidth of 1 hertz per channel, while those used in the Sky Survey had a bandwidth of 30 hertz per channel.

Related Topics:
1992 - Deep Space Network

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MOP drew the attention of the U.S. Congress, where the program was strongly ridiculed, and was cancelled a year after its start. SETI advocates did not give up, and in 1995 the nonprofit "SETI Institute" of Mountain View, California, resurrected the work under the name of Project "Phoenix", backed by private sources of funding. Project Phoenix, under the direction of Dr. Jill Tarter, previously Project Scientist for the NASA project, is a continuation of the Targeted Search program, studying roughly 1,000 nearby Sunlike stars. Seth Shostak also worked on Project Phoenix. From 1995 through March 2004, Phoenix conducted observing campaigns at the 64-meter Parkes radio telescope in Australia, the 140 Foot Telescope of the National Radio Astronomy Observatory in West Virginia, USA, and the Arecibo Observatory in Puerto Rico. The project observed the equivalent of 800 stars over the available channels in the frequency range from 1200 to 3000 MHz. The search was sensitive enough to pick up transmitters with power output equivalent to airport radars to a distance of about 200 light years.

Related Topics:
U.S. Congress - 1995 - Mountain View, California - Project Phoenix - Jill Tarter - Seth Shostak - Parkes radio telescope

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Allen Telescope Array

The SETI Institute is now collaborating with the Radio Astronomy Laboratory at UC Berkeley to develop a specialized radio telescope array for SETI studies, something like a mini-Cyclops array. The new array concept is named the "Allen Telescope Array" (ATA) (formerly, One Hectare Telescope ) after the project's benefactor Paul Allen. Its sensitivity will be equivalent to a single large dish more than 100 meters on a side. The array is being constructed at the Hat Creek Observatory in rural northern California. http://www.seti.org/site/pp.asp?c=ktJ2J9MMIsE&b=179146

Related Topics:
Allen Telescope Array - Paul Allen - Hat Creek Observatory

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The array will consist of 350 or more Gregorian radio dishes, each 6.1 meters (20 feet) in diameter. These dishes will essentially be commercially available satellite television dishes. The ATA is expected to be completed by 2007 at a very modest cost of $25 million USD. The SETI Institute will provide money for building the ATA while UC Berkeley will design the telescope and provide operational funding. Berkeley astronomers will use the ATA to pursue other deep space radio observations. The ATA is intended to support a large number of simultaneous observations through a technique known as "multibeaming", in which DSP technology is used to sort out signals from the multiple dishes. The DSP system planned for the ATA is extremely ambitious.

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SETI@home

Another interesting UC Berkeley effort called SETI@home was concieved in 1995 by David Gedye and began in May 1999, and heavily sponsored by The planetary Society. The existence of the SETI@home project means that any individual can become involved with SETI research by simply downloading screensaver software over the Internet. The software performs signal analysis on a downloaded 350 kilobyte "work unit" of SERENDIP IV SETI radio survey data, and then reports the results back over the Internet.

Related Topics:
SETI@home - 1999 - Planetary Society

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Over 5 million computer users in more than a hundred countries have signed up for SETI@home and have collectively contributed over 19 billion hours of computer processing time. The project is widely praised in the computer press as an effective exercise in home-grown distributed computing. As of June 22, 2004 the next generation of SETI@home was released to the public. It is based on the Berkeley Open Infrastructure for Network Computing (BOINC), which is being developed out of the UC Berkeley. SETI@home classic will soon retire as the next generation of distributive computing advances.

Related Topics:
Computer - Distributed computing - June 22 - 2004 - Berkeley Open Infrastructure for Network Computing

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