SETI@home - Revision history

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← Older revision		Revision as of 03:55, 28 May 2026
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	{{Infobox software		{{Infobox software
	\| name = SETI@home		\| name = SETI@home
	\| logo = SETI at home logo.png		\| logo = SETI@home logo.png
	\| logo caption = SETI@home logo		\| logo caption = SETI@home logo
	\| screenshot = SETI at home screensaver.~~png~~		\| screenshot = SETI@home custom background and logo screensaver.gif
	\| caption = The SETI@home screensaver displaying radio signal analysis in progress		\| caption = The SETI@home screensaver displaying radio signal analysis in progress
	\| description = SETI@home is a hibernating volunteer computing project hosted by the Space Sciences Laboratory at UC Berkeley, using the BOINC platform to search for extraterrestrial intelligence by analyzing radio telescope data from Arecibo and Green Bank.		\| description = SETI@home is a hibernating volunteer computing project hosted by the Space Sciences Laboratory at UC Berkeley, using the BOINC platform to search for extraterrestrial intelligence by analyzing radio telescope data from Arecibo and Green Bank.
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	'''SETI@home''' (pronounced "SETI at home") is a volunteer [[distributed computing]] project run by the [[Berkeley SETI Research Center]] and hosted by the [[Space Sciences Laboratory]] at the [[University of California, Berkeley]].<ref name="wikipedia-seti">{{cite web \|url=https://en.wikipedia.org/wiki/SETI@home \|title=SETI@home \|publisher=Wikipedia \|access-date=2026-05-26}}</ref> Its goal is to analyze radio telescope data in search of signals that could indicate extraterrestrial intelligence, making it one of many activities in the worldwide [[Search for Extraterrestrial Intelligence\|SETI]] effort. SETI@home ran as an active volunteer computing project from May 17, 1999, until March 31, 2020, when it entered an indefinite period of hibernation while the research team focused on analyzing accumulated data.<ref name="hibernation-announcement">{{cite web \|url=https://setiathome.berkeley.edu/old_news.php \|title=SETI@home hibernation announcement \|publisher=SETI@home, University of California, Berkeley \|date=2020-03-07 \|access-date=2026-05-26}}</ref>		'''SETI@home''' (pronounced "SETI at home") is a volunteer [[distributed computing]] project run by the [[Berkeley SETI Research Center]] and hosted by the [[Space Sciences Laboratory]] at the [[University of California, Berkeley]].<ref name="wikipedia-seti">{{cite web \|url=https://en.wikipedia.org/wiki/SETI@home \|title=SETI@home \|publisher=Wikipedia \|access-date=2026-05-26}}</ref> Its goal is to analyze radio telescope data in search of signals that could indicate extraterrestrial intelligence, making it one of many activities in the worldwide [[Search for Extraterrestrial Intelligence\|SETI]] effort. SETI@home ran as an active volunteer computing project from May 17, 1999, until March 31, 2020, when it entered an indefinite period of hibernation while the research team focused on analyzing accumulated data.<ref name="hibernation-announcement">{{cite web \|url=https://setiathome.berkeley.edu/old_news.php \|title=SETI@home hibernation announcement \|publisher=SETI@home, University of California, Berkeley \|date=2020-03-07 \|access-date=2026-05-26}}</ref>
			[[File:Arecibo Observatory Aerial View.jpg\|thumb\|The Arecibo Observatory in Puerto Rico was SETI@home's primary data source throughout most of the project's history. Data was recorded onto magnetic tapes and physically mailed to Berkeley for processing.]]
	[[File:Arecibo Observatory ~~aerial view~~.jpg\|thumb~~\|right~~\|The Arecibo Observatory in Puerto Rico was SETI@home's primary data source throughout most of the project's history. Data was recorded onto magnetic tapes and physically mailed to Berkeley for processing.]]

	SETI@home was the third large-scale use of volunteer computing over the Internet for research purposes, following the [[Great Internet Mersenne Prime Search]] (GIMPS), launched in 1996, and [[distributed.net]], launched in 1997.<ref name="spacenews-10th">{{cite web \|url=https://spacenews.com/seti-at-home-celebrates-10th-anniversary/ \|title=SETI@home Celebrates 10th Anniversary \|publisher=SpaceNews \|date=2009 \|access-date=2026-05-26}}</ref> With over 5.2 million participants worldwide at its peak, it was the volunteer computing project with the most participants recorded to date,<ref name="wikipedia-seti"/> and was recognized by the 2008 edition of the ''[[Guinness World Records]]'' as the largest computation in history.<ref name="guinness">{{cite web \|url=https://www.guinnessworldrecords.com/world-records/73215-largest-distributed-computing-project \|title=Largest distributed computing project \|publisher=Guinness World Records \|access-date=2026-05-26}}</ref>		SETI@home was the third large-scale use of volunteer computing over the Internet for research purposes, following the [[Great Internet Mersenne Prime Search]] (GIMPS), launched in 1996, and [[distributed.net]], launched in 1997.<ref name="spacenews-10th">{{cite web \|url=https://spacenews.com/seti-at-home-celebrates-10th-anniversary/ \|title=SETI@home Celebrates 10th Anniversary \|publisher=SpaceNews \|date=2009 \|access-date=2026-05-26}}</ref> With over 5.2 million participants worldwide at its peak, it was the volunteer computing project with the most participants recorded to date,<ref name="wikipedia-seti"/> and was recognized by the 2008 edition of the ''[[Guinness World Records]]'' as the largest computation in history.<ref name="guinness">{{cite web \|url=https://www.guinnessworldrecords.com/world-records/73215-largest-distributed-computing-project \|title=Largest distributed computing project \|publisher=Guinness World Records \|access-date=2026-05-26}}</ref>

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	Volunteers installed a free client program on their computers. When the machine was otherwise idle, the program downloaded a work unit from the SETI@home server, processed it, and returned the results automatically upon the next Internet connection. The software also featured an optional [[screensaver]] that displayed a real-time visualization of the signal analysis in progress, showing [[spectrogram]]s and signal-strength graphs.<ref name="universetoday">{{cite web \|url=https://www.universetoday.com/articles/setihome-is-on-pause-unfortunately-its-not-because-theyve-discovered-aliens \|title=SETI@home is on Pause \|publisher=Universe Today \|access-date=2026-05-26}}</ref>		Volunteers installed a free client program on their computers. When the machine was otherwise idle, the program downloaded a work unit from the SETI@home server, processed it, and returned the results automatically upon the next Internet connection. The software also featured an optional [[screensaver]] that displayed a real-time visualization of the signal analysis in progress, showing [[spectrogram]]s and signal-strength graphs.<ref name="universetoday">{{cite web \|url=https://www.universetoday.com/articles/setihome-is-on-pause-unfortunately-its-not-because-theyve-discovered-aliens \|title=SETI@home is on Pause \|publisher=Universe Today \|access-date=2026-05-26}}</ref>

	~~[[File:SETI at home Multi-Beam screensaver.png\|thumb\|left\|The SETI@home multi-beam screensaver, showing signal analysis in real time on a volunteer's computer.]]~~

	=== Signal detection algorithms ===		=== Signal detection algorithms ===
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	Each work unit was analyzed across hundreds of frequency sub-bands and drift rates to account for the [[Doppler shift\|Doppler frequency drift]] that would result from the relative motion between a transmitting planet and Earth.<ref name="wikipedia-seti"/>		Each work unit was analyzed across hundreds of frequency sub-bands and drift rates to account for the [[Doppler shift\|Doppler frequency drift]] that would result from the relative motion between a transmitting planet and Earth.<ref name="wikipedia-seti"/>
			[[File:BOINC Manager Screenshot.jpg\|left\|thumb\|SETI@home running in the BOINC Manager]]

	=== Work unit validation ===		=== Work unit validation ===

Al Piskun: first light

2026-05-26T21:04:27Z

first light

New page

{{Infobox software
| name = SETI@home
| logo = SETI at home logo.png
| logo caption = SETI@home logo
| screenshot = SETI at home screensaver.png
| caption = The SETI@home screensaver displaying radio signal analysis in progress
| description = SETI@home is a hibernating volunteer computing project hosted by the Space Sciences Laboratory at UC Berkeley, using the BOINC platform to search for extraterrestrial intelligence by analyzing radio telescope data from Arecibo and Green Bank.

| status = Hibernating
| category = Astrophysics / SETI
| compute = CPU & GPU
| dependencies = None

| developer = University of California, Berkeley
| author = David Gedye, David P. Anderson, Dan Werthimer
| sponsor = National Science Foundation, NASA, volunteer donations
| maintainer = Eric Korpela (current director)
| released = {{Start date and age|1999|05|17}}
| completed =
| discontinued =
| repository =

| programming language = C, C++
| operating system = Windows, Linux, macOS, Android, Solaris, FreeBSD, IBM AIX, HP-UX, IRIX, OS/2 Warp
| size =

| stats as of = March 2020
| active users = 91454
| total users = 1803163
| active hosts = 144779
| total hosts = 165178

| website = {{URL|https://setiathome.berkeley.edu/}}
| license = GPL-2.0-or-later
}}

'''SETI@home''' (pronounced "SETI at home") is a volunteer [[distributed computing]] project run by the [[Berkeley SETI Research Center]] and hosted by the [[Space Sciences Laboratory]] at the [[University of California, Berkeley]].<ref name="wikipedia-seti">{{cite web |url=https://en.wikipedia.org/wiki/SETI@home |title=SETI@home |publisher=Wikipedia |access-date=2026-05-26}}</ref> Its goal is to analyze radio telescope data in search of signals that could indicate extraterrestrial intelligence, making it one of many activities in the worldwide [[Search for Extraterrestrial Intelligence|SETI]] effort. SETI@home ran as an active volunteer computing project from May 17, 1999, until March 31, 2020, when it entered an indefinite period of hibernation while the research team focused on analyzing accumulated data.<ref name="hibernation-announcement">{{cite web |url=https://setiathome.berkeley.edu/old_news.php |title=SETI@home hibernation announcement |publisher=SETI@home, University of California, Berkeley |date=2020-03-07 |access-date=2026-05-26}}</ref>

[[File:Arecibo Observatory aerial view.jpg|thumb|right|The Arecibo Observatory in Puerto Rico was SETI@home's primary data source throughout most of the project's history. Data was recorded onto magnetic tapes and physically mailed to Berkeley for processing.]]

SETI@home was the third large-scale use of volunteer computing over the Internet for research purposes, following the [[Great Internet Mersenne Prime Search]] (GIMPS), launched in 1996, and [[distributed.net]], launched in 1997.<ref name="spacenews-10th">{{cite web |url=https://spacenews.com/seti-at-home-celebrates-10th-anniversary/ |title=SETI@home Celebrates 10th Anniversary |publisher=SpaceNews |date=2009 |access-date=2026-05-26}}</ref> With over 5.2 million participants worldwide at its peak, it was the volunteer computing project with the most participants recorded to date,<ref name="wikipedia-seti"/> and was recognized by the 2008 edition of the ''[[Guinness World Records]]'' as the largest computation in history.<ref name="guinness">{{cite web |url=https://www.guinnessworldrecords.com/world-records/73215-largest-distributed-computing-project |title=Largest distributed computing project |publisher=Guinness World Records |access-date=2026-05-26}}</ref>

== Background and origins ==

The concept for SETI@home emerged in 1995 when David Gedye, then a project manager at Starwave Corp., proposed using a virtual supercomputer composed of large numbers of Internet-connected computers to perform radio SETI analysis.<ref name="cacm2002">{{cite journal |last1=Anderson |first1=David P. |last2=Cobb |first2=Jeff |last3=Korpela |first3=Eric |last4=Lebofsky |first4=Matt |last5=Werthimer |first5=Dan |title=SETI@home: An Experiment in Public-Resource Computing |journal=Communications of the ACM |volume=45 |issue=11 |pages=56–61 |date=November 2002 |url=https://setiathome.berkeley.edu/sah_papers/cacm.php |access-date=2026-05-26}}</ref> Prior to SETI@home, radio SETI projects relied on special-purpose supercomputers located at the telescope facility itself.<ref name="cacm2002"/> Gedye partnered with [[University of Washington]] astronomer Woody Sullivan, who suggested contacting Dan Werthimer, whose [[SERENDIP]] project was already conducting SETI observations at [[Arecibo Observatory|Arecibo]], and with David P. Anderson, a specialist in distributed computing at UC Berkeley's Space Sciences Laboratory.<ref name="spacenews-10th"/>

The project was initially funded with just $100,000 from [[The Planetary Society]] and [[Paramount Pictures]], and in its early years received donated server hardware from companies such as Sun Microsystems and Intel before transitioning to a purely donation-supported model.<ref name="spacenews-10th"/>

SETI@home was publicly launched on May 17, 1999. Within the first week, nearly 300,000 computers were already processing data from Arecibo. Within a few months, more than one million volunteers had signed up across 223 countries.<ref name="digitaltrends">{{cite web |url=https://www.digitaltrends.com/cool-tech/setihome-citizen-scientists-extraterrestrial-intelligence/ |title=How SETI@home accelerated alien hunting with an army of armchair astronomers |publisher=Digital Trends |date=2020-09-09 |access-date=2026-05-26}}</ref>

== Scientific goals ==

SETI@home was established with two primary goals:<ref name="cacm2002"/>

# To conduct useful scientific work in an observational analysis aimed at detecting intelligent life beyond [[Earth]].
# To demonstrate the viability and practicality of the "volunteer computing" concept.

The second goal is considered to have succeeded fully: the [[Berkeley Open Infrastructure for Network Computing|BOINC]] platform, developed from technology pioneered by SETI@home, now supports dozens of computationally intensive scientific projects across many disciplines.<ref name="wikipedia-seti"/> The first goal, as of 2026, has produced no conclusive evidence of extraterrestrial intelligence, though the project identified a number of scientifically interesting candidate signals for follow-up observation.<ref name="wikipedia-seti"/>

== How it worked ==

=== Data acquisition ===

SETI@home collected observational data "piggyback" or "passively" while [[Arecibo Observatory|Arecibo]] (and later the [[Green Bank Telescope]]) were being used for other scientific programs.<ref name="wikipedia-seti"/> At Arecibo, data was sampled and written to high-density [[Digital Linear Tape|DLT]] cartridges at a rate of approximately one 35 GB tape per day. Because Arecibo lacked a broadband Internet connection, tapes were physically mailed to the SETI@home laboratory at UC Berkeley.<ref name="cacm2002"/> Once received, the data was divided both in the [[time domain]] and [[frequency domain]] into work units of approximately 107 seconds in duration, each roughly 0.35 [[megabyte|MB]] in size, overlapping in time but not in frequency.<ref name="wikipedia-seti"/>

=== Client software and screensaver ===

Volunteers installed a free client program on their computers. When the machine was otherwise idle, the program downloaded a work unit from the SETI@home server, processed it, and returned the results automatically upon the next Internet connection. The software also featured an optional [[screensaver]] that displayed a real-time visualization of the signal analysis in progress, showing [[spectrogram]]s and signal-strength graphs.<ref name="universetoday">{{cite web |url=https://www.universetoday.com/articles/setihome-is-on-pause-unfortunately-its-not-because-theyve-discovered-aliens |title=SETI@home is on Pause |publisher=Universe Today |access-date=2026-05-26}}</ref>

[[File:SETI at home Multi-Beam screensaver.png|thumb|left|The SETI@home multi-beam screensaver, showing signal analysis in real time on a volunteer's computer.]]

=== Signal detection algorithms ===

The client software searched for five categories of signals that distinguish genuine candidates from background [[electromagnetic noise|noise]]:<ref name="wikipedia-seti"/>

# '''Spikes''' in [[power spectrum|power spectra]]
# '''Gaussians''': rises and falls in transmission power that may represent a telescope beam's [[main lobe]] passing over a radio source
# '''Triplets''': three power spikes in a row
# '''Pulses''': repeating signals possibly representing narrowband digital-style transmissions
# '''Autocorrelations''': matching signal waveforms using [[autocorrelation]]

The core technique involved applying large numbers of [[discrete Fourier transform]]s (DFTs) at various [[chirp]] rates and durations, essentially equivalent to simultaneously tuning many narrow radio channels and looking for unexplained excess power. Formally, for a sampled time-series signal <math>x[n]</math>, the discrete Fourier transform at frequency bin <math>k</math> is:

<math>X[k] = \sum_{n=0}^{N-1} x[n] \cdot e^{-i 2\pi k n / N}</math>

Each work unit was analyzed across hundreds of frequency sub-bands and drift rates to account for the [[Doppler shift|Doppler frequency drift]] that would result from the relative motion between a transmitting planet and Earth.<ref name="wikipedia-seti"/>

=== Work unit validation ===

To guard against fraudulent or erroneous results, every work unit was sent to multiple computers (a practice called "initial replication," typically set to a value of 2). Credit was only awarded once a minimum number of returned results agreed with one another (the "minimum quorum"). If disagreement occurred, additional copies of the work unit were distributed until a quorum was reached. The final credit granted to all machines returning the correct result was set to the lowest value claimed among them.<ref name="wikipedia-seti"/>

== From Classic to BOINC ==

The initial software platform, known as "SETI@home Classic," ran from May 17, 1999, to December 15, 2005. This program was capable only of running SETI@home tasks and required volunteers to manually download new software with each algorithm update.<ref name="wikipedia-seti"/>

In 2005, the project transitioned to the [[Berkeley Open Infrastructure for Network Computing|BOINC]] platform, which had been developed by David P. Anderson with funding from the [[National Science Foundation]].<ref name="setiathome-iopscience">{{cite journal |last=Anderson |first=David P. |display-authors=et al. |title=SETI@home: Data Acquisition and Front-End Processing |journal=The Astronomical Journal |date=2025 |url=https://iopscience.iop.org/article/10.3847/1538-3881/ade5a7 |access-date=2026-05-26}}</ref> BOINC allowed algorithm updates without requiring user intervention, enabled volunteers to contribute to multiple scientific projects simultaneously, and opened the door to new types of signal analysis.<ref name="transition">{{cite web |url=https://setiathome.berkeley.edu/transition.php |title=SETI@home's transition to BOINC |publisher=SETI@home, UC Berkeley |access-date=2026-05-26}}</ref>

=== SETI@home Enhanced ===

On May 3, 2006, distribution of a new version called "SETI@home Enhanced" began. Taking advantage of increased desktop computing power since 1999, this version was approximately twice as sensitive to Gaussian signals and certain classes of pulsed signals as the original BOINC-based release. Application builds were also produced with processor-specific optimizations, especially for [[Intel]] instruction sets, allowing faster execution on compatible hardware.<ref name="wikipedia-seti"/>

=== GPU acceleration ===

With assistance from [[NVIDIA]], SETI@home developed a client application using the [[CUDA]] parallel computing platform. This GPU-accelerated version achieved speeds from 2 to 10 times faster than the CPU-only version, depending on hardware. For example, a GeForce GTX 280 was more than twice as fast as a high-end 3.2 GHz Intel Core i7 965 CPU running the same analysis.<ref name="nvidia-cuda">{{cite web |url=https://grib.upf.edu/nvidia-cuda-technology-dramatically-advances-the-pace-of-scientific-research/ |title=NVIDIA CUDA Technology Dramatically Advances the Pace of Scientific Research |access-date=2026-05-26}}</ref> GPU support via CUDA was formally incorporated into SETI@home in 2015.<ref name="wikipedia-seti"/>

== AstroPulse ==

AstroPulse was a companion application to SETI@home designed to search for short, broadband radio pulses in the same Arecibo data. Where SETI@home concentrated on narrowband continuous signals, AstroPulse used [[coherent dedispersion]] to search for brief but powerful bursts that could indicate rapidly rotating [[pulsar]]s, evaporating primordial [[black hole]]s, or previously unknown astrophysical phenomena, as well as another possible signature of extraterrestrial intelligence.<ref name="planetary-astropulse">{{cite web |url=https://www.planetary.org/articles/setiathome_20030925 |title=New and Improved SETI@home |publisher=The Planetary Society |date=2003-09-25 |access-date=2026-05-26}}</ref> AstroPulse was one of the earliest test applications for BOINC. Beta testing of its final public release was completed in July 2008, and distribution of work units to qualifying machines began in