---
title: "SETI@home"
chunk: 2/4
source: "https://en.wikipedia.org/wiki/SETI@home"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:12:40.390913+00:00"
instance: "kb-cron"
---

== Technology ==
Anybody with an at least intermittently Internet-connected computer was able to participate in SETI@home by running a free program that downloaded and analyzed radio telescope data.
Observational data were recorded on 2-terabyte SATA hard disk drives fed from the Arecibo Telescope in Puerto Rico, each holding about 2.5 days of observations, which were then sent to Berkeley. Arecibo does not have a broadband Internet connection, so data must go by postal mail to Berkeley. Once there, it is divided in both time and frequency domains work units of 107 seconds of data, or approximately 0.35 megabytes (350 kilobytes or 350,000 bytes), which overlap in time but not in frequency. These work units are then sent from the SETI@home server over the Internet to personal computers around the world to analyze.
Data was merged into a database using SETI@home computers in Berkeley. Interference was rejected, and various pattern-detection algorithms were applied to search for the most interesting signals.
The project used CUDA for GPU processing starting in 2015.
In 2016 SETI@home began processing data from the Breakthrough Listen project.

=== Software ===

The SETI@home volunteer computing software ran either as a screensaver or continuously while a user worked, making use of processor time that would otherwise be unused.
The initial software platform, now referred to as "SETI@home Classic", ran from May 17, 1999, to December 15, 2005. This program was only capable of running SETI@home; it was replaced by Berkeley Open Infrastructure for Network Computing (BOINC), which also allows users to contribute to other volunteer computing projects at the same time as running SETI@home. The BOINC platform also allowed testing for more types of signals.
The discontinuation of the SETI@home Classic platform rendered older Macintosh computers running the classic Mac OS (pre December, 2001) unsuitable for participating in the project.
SETI@home was available for the Sony PlayStation 3 console.
On May 3, 2006, new work units for a new version of SETI@home called "SETI@home Enhanced" started distribution. Since computers had the power for more computationally intensive work than when the project began, this new version was more sensitive by a factor of two concerning Gaussian signals and to some kinds of pulsed signals than the original SETI@home (BOINC) software. This new application had been optimized to the point where it would run faster on some work units than earlier versions. However, some work units (the best work units, scientifically speaking) would take significantly longer.
In addition, some distributions of the SETI@home applications were optimized for a particular type of CPU. They were referred to as "optimized executables", and had been found to run faster on systems specific for that CPU. As of 2007, most of these applications were optimized for Intel processors and their corresponding instruction sets.
The results of the data processing were normally automatically transmitted when the computer was next connected to the Internet; it could also be instructed to connect to the Internet as needed.

== Statistics ==
With over 5.2 million participants worldwide, the project was the volunteer computing project with the most participants to date. The original intent of SETI@home was to utilize 50,000–100,000 home computers. Since its launch on May 17, 1999, the project has logged over two million years of aggregate computing time. On September 26, 2001, SETI@home had performed a total of 1021 floating point operations. It was acknowledged by the 2008 edition of the Guinness World Records as the largest computation in history. With over 145,000 active computers in the system (1.4 million total) in 233 countries, as of 23 June 2013, SETI@home had the ability to compute over 668 teraFLOPS. For comparison, the Tianhe-2 computer, which as of 23 June 2013 was the world's fastest supercomputer, was able to compute 33.86 petaFLOPS (approximately 50 times greater).

== Project future ==
There were plans to get data from the Parkes Observatory in Australia to analyze the southern hemisphere. However, as of 3 June 2018, these plans were not mentioned in the project's website. Other plans include a Multi-Beam Data Recorder, a Near Time Persistency Checker and Astropulse (an application that uses coherent dedispersion to search for pulsed signals). Astropulse will team with the original SETI@home to detect other sources, such as rapidly rotating pulsars, exploding primordial black holes, or as-yet unknown astrophysical phenomena. Beta testing of the final public release version of Astropulse was completed in July 2008, and the distribution of work units to higher spec machines capable of processing the more CPU intensive work units started in mid-July 2008.
On March 31, 2020, UC Berkeley stopped sending out new data for SETI@Home clients to process, ending the effort for the time being. The program stated they were at a point of "diminishing returns" with the volunteer processing and needed to put the effort into hibernation while they processed the results.