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  1. #1
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    SETI@Home FAQ and SETI History

    What is SETI@Home?

    SETI is the Search for Extra-Terrestrial Intelligence, which strives to answer the question "Are We alone in the Universe?". In 1999 The Planetary Society started SETI@Home as a screen saver, which utilized the idle time on home PCs to analyze data from the Arecibo, Puerto Rico, radio telescope. (The movie Contact was filmed in part on location at the observatory site.) SETI@Home is one of the first distributed computing projects and is certainly the largest, having had over one million users in countries all over the world during it's decade-long history. Currently there are almost 200,000 users and about 300,000 computers running SETI@Home. As of 2004, SETI@Home uses a general purpose distributed computing platform called BOINC, Berkley Open Infrastructure for Network Computing, developed at the University of California Berkeley. BOINC has a very user-friendly interface and is easy to set-up and maintain. It was designed specifically to run in the background with minimal interference on everyday computing.

    How does SETI@Home work?

    Berkeley has a collection of hardware that sits on top of the main receiver package at Arecibo. This hardware collects radio signals across many bands from whatever direction the telescope happens to be pointed. By using this 'piggy-back' method, SETI@Home does not directly use telescope time, it simply records what is already streaming into the telescope from space. These recordings are then sent to Berkeley where they are divided into blocks of data called 'work units'. The work units are cataloged and cued-up to be sent out to SETI@Home participants. The BOINC software, which regularly checks in with Berkeley, downloads work units as needed then analyzes the data for repeating signals and other anomalies, flagging certain results. When a work unit is complete the results are stored on the home computer until transfered to Berkeley, where the results are stored in a temporary database for future analysis. After transfer it's erased on the home machine to make room for more work units.

    What happens if there's a computation error?

    All work units are sent out to two different computers. When both results arrive at Berkeley they are compared to each other. If the results agree then both computers get credited for completing the work unit. If the results do not agree a third copy of the raw data is sent to a third computer to be processed and those results are compared to the first two results. Results are not stored in the science database until at least two computers have the same results, at which time those two computers are credited for completing the work unit. Bogus results are rare but they happen. By only recognizing duplicate results from different machines, Berkeley maintains the integrity of the data analysis process.

    What are Cobblestones and RAC?

    SETI@Home credit is officially awarded in units called "Cobblestones" for historic purposes but is often referred to as simply 'credits'. Each work unit is worth a certain number of Cobblestones, depending on the amount of processor time it takes to complete on a standardized computer system running the base SETI@Home application. Another term often seen in SETI@Home conversation is 'RAC', or Recent Average Credit. RAC is calculated using a fairly complex formula but is basically the average daily output of a given computer or participant over the last 15-20 days.

    Who are the SETI Team?

    Daniel Edgar, Founder, SETI Team:
    "We are a group of hobbyists who overclock our computers to achieve maximum performance."
    We run SETI@Home not just for the science but for the competition and companionship of a shared goal. Most of us run SETI part-time when we're using our computer for light tasks, like web browsing and e-mail, and/or when our computer is completely idle, like when we're away at work or school. Many of us have SETI 'farms'. Similar to server farms, SETI farms are a collection of two or more computers assembled for an express purpose - in our case processing as much SETI@Home data as possible in the shortest time possible. While a large part of our team's computing power does come from SETI farms an even larger part comes from all the part-time crunchers out there. currently ranks 6th in the world for most data processed. RAC varies over time but we have been moving back and forth between 5th and 7th in the world for the past couple of years. We feel this is very good because the number of members we have is fairly small compared to most other teams near us in the ranks. Part of the reason for this is overclocking. Since most of our computers are running 15-25% faster than their design speed we also process 15-25% more data than the average computer!
    In addition there are SETI@Home 'optimizers' written by fellow SETI@Home participants. The base x86 Berkekely application is designed for use on any x86 computer (Intel and AMD machines most of us own) so it cannot take advantage of certain Instruction Sets, like SSE3 and SSSE4, imbedded in modern processors. Optimizers are specific applications that replace the standard Berkeley-issued application and are written specifically to take advantage of those advanced Instruction Sets. Berkeley is aware of these optimizers and although it cannot officially sanction them (because they would then be respensible for supporting them as well) they do recognise their use. In the end it's all about the science and if the optimizers speed up the data processing step no one's complaining.

    How do I sign up for the SETI Team?

    Getting involved in SETI@Home and becoming an SETI Team member is easy. All you need is a few minutes to set it up BOINC, a valid e-mail address, and a little idle computer time you're willing to donate to science. Just follow these step-by-step instructions.

    It takes all of us to make the Team work.
    Anything you can do to help is appriciated!

    The "Useful information, FAQ and Instructions" thread started by Mictlan in 2003 can be found here.
    Last edited by QuietIce; 05-27-10 at 10:42 AM.

  2. #2
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    A brief history of SETI

    For millennia people have looked at the stars and wondered about the heavens. In the 20th Century, with the advent of radio, some thoughts have turned a corner and the possibility of life Out There was tossed about in quiet back rooms and corners bars. The earliest of radio astronomers listened to nearby stars and maybe, just maybe, thought of the possibility of life on planets circling those stars, but few would admit such thoughts. In 1959 all of that changed. A pair of young researchers at Cornell University, Philip Morrison and Giuseppe Cocconi, discussed how other civilizations might communicate and submitted a short, two-page article to Nature Magazine. Nature ran the article in their 19 September 1959 issue and SETI, in one shot, became at least semi-respectable in the scientific community. That same year another young researcher at the National Radio Astronomy Observatory (NRAO) in Green Bank, WV, proposed extended observations of two nearby stars. Tau Ceti and Epsilon Eridani are both very close neighbors and have radiant properties very similar to our sun. On 8 April 1960 NROA started observations of both stars and for the next few months recorded 150 hours of radio waves across 7200 channels with their 85’ dish but no signs of intelligent life were found. Of course, the radio data collected didn’t go to waste; unique characteristics of both stars were noted for future reference and analysis.

    Many SETI conferences were held and much theoretical work was done during the 1960’s but no dedicated radio telescope time was spent searching specifically for intelligent life. It wasn’t until 1971 that SETI started coming to life as an observational science once again. In late 1971-1972 the NROA once again observed the nearest stars for signs of life. The radio dishes were much bigger, a 300-foot and a 140-foot dish, the equipment was far more sensitive, and nine stars were observed instead of the original two but the new SETI search only used 13 hours of dish time over it’s two year span. Starting in 1972 the program was expanded to include another 674 stars and over 500 hours of dish time was spent from 1972-1976 looking for extraterrestrial signals to no avail.

    The Big Ear is a very different kind of radio telescope. Designed in the 1950’s with construction completed in 1963, the Big Ear is a kind of radio reflector telescope of huge proportions. The primary reflector, a flat tilting surface 340’ long and 100’ tall, is used for aiming the radio telescope. The focusing reflector, a parabolic surface 360’ long, 70’ tall, and fixed in place, is used to focus the signal down to a receiving “horn”. Between the primary and the parabolic reflectors was a ground plane of aluminum covered concrete measuring 280’ wide and 500’ long. The “horn” is a type of receiver used in very early radio astronomy as an antenna but the Big Ear was using its horn as the last stop for the huge signal it was collecting through the rest of the structure. From 1963-1972 the Big Ear was used for conventional radio astronomy and made quite a name for itself discovering a multitude of quasars and new, deep space pulsars. Starting in 1972 the Big Ear was used exclusively for SETI observations, which scanned approximately 50 channels in its search. Most of the work done on SETI was through volunteer work by both students and faculty from Ohio State University.

    On 15 August 1977 the Big Ear received what has come to be known as the “WOW! Signal”. This odd name is taken from the scribbled note made by Jerry Ehman on the paper record of the previous night’s data he was examining. A very strong signal was detected for about 72 seconds that night. The scale used on the recording was a signal to noise ratio (or SNR) which varied from 1 to 35. A record was made every 12 seconds of the current SNR of any signals being received. The record went “6EQUJ5” representing an SNR of 6, 14, 26, 30, 19, 5, and because of the Big Ear’s configuration was determined to be a point source in the sky, not a local moving object as would be detected from aircraft or Earth orbiting satellites. A signal of this type has never been observed since. In 1998 the Big Ear shut down and was bulldozed under in 1999 for real estate development. It is now a golf course with State Dedication Plaques nearby to commemorate the site.

    In 1970 NASA started leaning toward SETI. For almost a decade NASA sponsored programs, seminars, workshops and feasibility studies about SETI. By 1979 two major programs had been outlined. One was similar to previous “targeted” studies, where searches are carried out only on relatively close, sun-similar stars. This program was favored by the NASA Ames Research Center. The other was the “whole sky survey” where the whole sky is slowly scanned, star by star. This was the approach the Jet Propulsion Laboratory (JPL) favored. Both had good points and bad points and, in the end, NASA decided to pursue both avenues of research. NASA Ames would carry out the targeted search using the 1000’ dish in Arecibo, Puerto Rico. This search would observe local, sun-like stars covering a radio spectrum from 1 GHz to 3 GHz and would use its Multi-Channel Spectrum Analyzer, which could gulp down a 20 MHz wide band at one time. JPL would start its all-sky mapping using the 112’ dish at the Deep Space Communications Complex in Goldstone, CA. They would observe all the stars from 1 to 10 GHz and use their Wide Band Spectrum Analyzer, which could take in 320 MHz at a time. Both searches started on 12 October, 1992 and were abruptly ended a year later by Federal budget cuts. Although the NASA sponsored radio telescope search didn’t continue for long NASA’s long-time investment in SETI research and development made SETI a credible science no longer stuck on the fringe.

    When NASA was forced to drop the ball in 1993 two private organizations, the SETI Institute and The Planetary Society, picked up the biggest parts of the SETI search NASA had abandoned, albeit on a smaller scale. The SETI Institute was founded in 1984 in California’s Silicon Valley and had already done a lot of SETI research under NASA contracts during the 80’s and early 90’s. In February 1995 the SETI Institute launched Project Phoenix, a continuation of the NASA Ames research using the Arecibo dish and conducting a targeted search of stars within 200 light-years (LY) of Earth. Project Phoenix continued for almost 10 years until February 2004. The SETI Institute has also started several new types of searches called optical SETI research, which looks for signs of intelligent, visible light activity. In recent years the SETI Institute has partnered with the University of California Berkley to build the Allen SETI Array, named after its largest contributor Paul Allen of Microsoft fame. In addition to radio and visible light searches, the SETI Institute also does research into various other aspects of SETI including the discovery of extra-solar planets, astrobiology, “extreme” biology (life forms living in extreme and humanly deadly environments), and other work on local planetary research.

    The Planetary Society (TPS) has long been a sponsor of SETI research. In the 1980’s it supported several small-scale SETI projects by Paul Horowitz of Harvard University. In 1995 Horowitz began Project BETA, or Billion-channel Extra-Terrestrial Assay, using the 85’ dish at the Harvard-Smithsonian Observatory. Project BETA ended in 1999 when the dish was badly damaged by storms. In 1996 TPS, along with other sources, started sponsoring Project SERENDIP, a radio all-sky survey led by Dan Werthimer of U.C. Berkeley. Project SERENDIP uses its own receiver mounted above the main receiver at Arecibo. Instead of using actual radio telescope time, SERENDIP processes radio signals from wherever the dish happens to be pointed and doesn’t interfere with normal dish operations. Since SERENDIP is an all-sky survey individual targeting of stars is not required, so this “piggy-back” method of observation is an ideal solution combining the valuable observational power of the Arecibo dish with a relatively low-cost data collection method since individual dish time is not needed.

    Currently, Project SERENDIP data is what we process using SETI@Home. SETI@Home is one of the first “distributed computing” projects and certainly the most wide-spread at this time. Earlier versions of SETI@Home used an independent “screen saver” program distributed by The Planetary Society. Project SERENDIP data is divided up into workable chunks called “work units” (WUs) and distributed to host PCs through Berkley’s SETI servers. Various servers divide the data into WUs, distribute the WUs, collect the processed units, analyze and compare the processed units to each other (all SETI WUs are processed by two different hosts to avoid errors), record/earmark special results, and compare previous results with current results from the same source. Since 2004 SETI@Home has been part of the Berkley Open Infrastructure for Network Computing, or BOINC, a general purpose distributed computing management program that can monitor and run several distributed science projects. Currently there are over 200,000 active users running SETI@Home on over 350,000 hosts in over 200 different countries around the world. The average floating point calculations per second of all these hosts is over 400 TeraFLOPS, almost as much as the new Ranger Super-computer.

    SETI has come a long way from ancient times as man looked up and first noticed the stars. Intelligent life has to be out there, the only questions are "Where are they?" and "How do they communicate?". SETI@Home is helping find the answers to those questions.
    Last edited by QuietIce; 11-19-09 at 09:00 AM.

  3. #3
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  4. #4
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    That is a GREAT history lesson! Definitely worth the read.
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  5. #5
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    Wow, you've been busy. Bored at work?
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  6. #6
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    Good one to sticky, maybe get a few more people to donate their spare CPU power to OCforum club?

    useless trivia: radio signals from Earth (TV, radio, etc) has not reached any other stars. Scientists estimated our most powerful transmitter is good for up to 2 light years, about half the distance to the nearest star Alpha Centauri and a lot short of the nearest star that has exo-planets (about light 10 years away)
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  7. #7
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    Thanks guys!

    Are there any other FAQs you can think of?

    Quote Originally Posted by 4GHZ_or_bust View Post
    Good one to sticky, maybe get a few more people to donate their spare CPU power to OCforum club?

    useless trivia: radio signals from Earth (TV, radio, etc) has not reached any other stars. Scientists estimated our most powerful transmitter is good for up to 2 light years, about half the distance to the nearest star Alpha Centauri and a lot short of the nearest star that has exo-planets (about light 10 years away)
    I'd like to read that article to see what assumptions they made to come to that conclusion. If we had a listening post sitting 2 LY away we may not be able to detect our own signals but technology is a wonderful thing and not to be taken lightly.

    You mean exo-planets big enough and/or close enough to their sun and/or oriented correctly for us to have found them? There are a lot of variables there and detecting exo-planets is a very young science.

    50 years ago the first microchips were patented. Look how far we've come in that short time ...
    Quote Originally Posted by freakdiablo View Post
    Wow, you've been busy. Bored at work?
    Work ...???
    Last edited by QuietIce; 11-19-09 at 03:33 PM.

  8. #8
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    QIce, these new info threads are excellent. Thanks for taking the time to organize them. These will be a great place to point curious friends.
    Last edited by Sephis; 11-19-09 at 11:57 PM.
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  9. #9
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    What is the average download and upload usage?
    I would love to get involved but do not have unlimited usage on my ADSL
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