ParaNet BBS/seti
From KB42
ParaNet BBS/seti
| File Name: | seti.txt |
|---|---|
| Author: | Unknown |
| Date: | Unknown |
| Posting BBS: | Unknown |
| BBS Main Page: | ParaNet Main Page |
| Key Words: | ParaNet, UFO, Ufology |
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ParaNet File Number: 00210
THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE
(S E T I)
Our Milky Way Galaxy is only one of 10 billion galaxies in the presently
observable universe. Our Sun is just one of some 300 billion stars in our
galaxy alone. Astronomers have confirmed that the Sun and the galaxy, which
make our existence possible, are not unusual or basically different from other
galaxies and stars.
A few generations ago, astronomers believed that planetary systems were
extremely rare--that our solar system and our Earth with its life-supporting
environment might well be unique. Chemists and biologists knew little if
anything about the processes that led to the origin of life. In the last
fifteen years, however, a number of important discoveries have strongly
suggested that there is a fundamental relationship between the origin and
evolution of life and the origin and evolution of the universe.
Advances in astronomy and physics have given renewed support to the concept
that planets are not rare exceptions, but are a natural part of the star
formation process and may number in the hundreds of millions in our galaxy
alone. [In December 1984, the National Science Foundation announced that a
team of Arizona astronomers had detected a possible solar system around Beta
Pictoris, a star 53 light years from Earth.] Recent biological experiments
applying natural energy sources to molecules have produced some of the organic
building blocks that make up the chemistry of life. Radio astronomers have
discovered that many organic molecules exist even in the depths of
interstellar space. Elements identified in these molecules include hydrogen,
nitrogen, oxygen, carbon, silicon, and phosphorus. Earth has been without life
only a small fraction of its age, which leads many scientists to look upon the
formation of life on other suitable planets as very likely. Once begun, and
given billions of years of relative stability, life may achieve intelligence
and, in some cases, may evolve into a technological civilization.
One direct way of testing whether intelligent life exists beyond our solar
system is to search for an artificially generated radio signal coming from
interstellar space. As an example, ultrahigh frequency and microwave radio
signals emanating from Earth are expanding into space at the speed of light.
This radio, radar, and television "leakage" of ours currently fills a sphere
nearly 100 light-years in diameter. The same phenomenon would serve to
announce the presence of other intelligent life. Moreover, advanced
civilizations might be operating radio beacons, possibly to attract the
attention of emerging societies and bring them into contact with a community
of long-established intelligent societies existing throughout the galaxy.
Either type of signal (leakage or beacon) would be easiest to detect at
frequencies where the background radio noise is minimal. One of the quietest
regions of the electromagnetic spectrum is the "microwave window" that lies in
the frequency band between 1000 and 10,000 megahertz (MHz). It is reasonable
to assume that others wishing to establish interstellar contact by radio might
choose this band.
The search for extraterrestrial intelligence (SETI) is not new, having first
been proposed by U.S. scientists in 1959. Since that time, numerous scientific
and technical studies have been made on an international scale, and more than
30 radio searches have been attempted, covering only a minute area of search
space. What is new today is the available technology. Radio telescopes on
Earth are sufficiently sensitive to detect signals no stronger than some
leaving Earth at distances of a thousand light-years or more. The 305 meter
(1000-ft) diameter radio telescope at Arecibo, Puerto Rico, could detect
transmissions from nearby stars that are less powerful but similar to our own
television and radars. Advances in computers and data processing techniques
now make it possible to search automatically through millions of incoming
radio signals each second and, if it is present, to identify a signal
transmitted by an intelligent society.
The NASA SETI Program is nearing the end of a 5-year research and development
phase, using existing radio telescopes and advanced electronic techniques to
develop prototype SETI instrumentation. The program is being jointly carried
out by the Jet Propulsion Laboratory (JPL) at Pasadena, California, and the
NASA Ames Research Center at Moffet Field, California. Leading radio
scientists from the national laboratories and academic community have also
joined together in the SETI Science Working Group to assist the JPL-Ames team
in developing the instrumentation and the search strategy.
The proposed plan involves two complementary search modes that are designed to
cover a range of possibilities. One mode is an all-sky survey that will search
the entire celestial sphere over a wide frequency range (1200 to 10,000 MHz
plus spot bands up to 25,000 MHz) to cover the possibility that there may be a
few civilizations transmitting strong signals, possibly as interstellar
beacons. Longer observing times may be allocated to directions that include a
large number of stars, especially the galactic plane. The radio telescopes
employed will be the 34-meter (112-ft) diameter antennas that are part of
NASA's Deep Space Network. The survey will be conducted by moving the
telescope across the sky at a constant rate. It will cover at least 10,000
times more frequency space than all previous survey attempts, will be about
300 times more sensitive, and will take about 5 years to complete.
The second mode is a high-sensitivity targeted search that will look for weak
signals originating near solar-type stars within 80 light-years distance from
Earth. The objective is to examine the possibility that nearby civilizations
may have radio transmitters no more powerful than our own. Some stellar
clusters and nearby galaxies will also be observed. The frequency range
covered will be 1200 to 3000 MHz plus spot bands between 3000 and 10,000 MHz.
To achieve very high sensitivity, the targeted search will use some of the
largest radio telescopes available, including the 305-meter (1000-ft) diameter
antenna at Arecibo, Puerto Rico, and the Deep Space Network's 64-meter
(210-ft) diameter antennas. The number of targets covered will be much larger
than previous searches and the range of frequencies covered will be thousands
of times greater. The targeted search is expected to take about 3 years to
complete.
Current astrophysical knowledge and the available technology make the SETI
observing program both timely and feasible. Timeliness also relates to the
rapidly-increasing sources of radio frequency interference (RFI) in the
microwave band. Portions of the microwave spectrum that directly concern SETI
ar subject to allocation to numerous users worldwide, emphasizing the need to
proceed with SETI while it remains economically possible with our current
technology. If the use of the microwave spectrum continues to increase at its
present rate, the greatest exploration opportunity in the history of mankind
may be placed economically and technologically beyond our reach for the
foreseeable future.
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S E T I SEARCH SUMMARY
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SEARCH PARTICULARS SKY SURVEY TARGET SEARCH
______________________________________________________________________
Area Coverage All directions 1000 stars, regions
Signal search Continuous Wave Pulses, drifting CW
Frequency coverage 1200-10,000 MHz + 1200-3000 MHz + spot
spot bands bands
Frequency resolution 1000, 32 Hz 1000, 32, 1 Hz
Receiver bandwidth Wide (~250 MHz) Narrow (~10 MHz)
Observing time per
direction at each 0.3 - 3 sec 100-1000 sec
frequency setting
Channels analyzed ~10 million ~10 million
per second
Antenna diameter 34 meters 305 and 64 meters
Search duration ~5 years ~3 years
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