- Arecibo Radio Telescope - NAIC - Arecibo Radio Telescope
Near the city of Arecibo in Puerto Rico, there is a large radio telescope, set in a naturally-formed depression. With a diameter of 305 meters, it is the largest single-aperture radio telescope ever built. It is operated by Cornell University, of the USA. The dish does not rotate, but a receiver suspended above collects signals reflected from different parts of the spherical dish. Completed in 1963, it has undergone various refurbishments and upgrades since then. It can serve as a listening device, receiving radio waves from the sky, or it can also emit radio waves, and thus act as a radar device.
David Gedye Started SETI@Home to Look for Extraterrestrial Signals
In 1994/1995 David Gedye started to set up the SETI@home programme, to use data from the Arecibo telescope and distribute it to thousands of home computers, for analysis. Many people contributed their time and talents to the project. Funding came initially from The Planetary Society and other groups. On May 17th 1999 SETI@home was launched to the public. Within three months 1 million people had subscribed, downloaded the client software needed and were processing work units. Good-natured competition arose, as people vied with each other to increase the number of work units they analysed, sending back the results to the project, for which they would receive notional 'credits'.
In December 2005 the original SETI@home project (now named SETI@home Classic) was closed down. The client software had been written exclusively for the project. It was one of the first volunteer computing projects, and had not been designed to have a high level of security. Some of the participants had tried to cheat the system by falsifying the results that they sent to the project, and artificially boost the number of credits that they received.
BOINC Supersedes SETI@Home Classic
In 2002 an entirely new version of the client software was released – BOINC. This is a more general platform and although originally designed with SETI@Home in mind, it can be used with many different distributed applications. There are now more than eighty of these in operation, in topics such as molecular biology, climatology, mathematics, medicine and astrophysics. BOINC is software that runs on your computer and can use spare CPU cycles that are available when the computer is otherwise idle. So whatever a user is not making use of, BOINC can use. Included is the BOINC Credit System, which is designed to avoid cheating. It does this by validating the work results, before issuing any credits.
There are very few steps needed to make use of the BOINC software to look for signals from extraterrestrials:
- Read the terms and policies of the SETI@Home project at http://setiathome.berkeley.edu
- Download the BOINC software from http://boinc.berkeley.edu/download.php
- Install and run the downloaded software : when prompted, enter the URL http://setiathome.berkeley.edu
Once up and running, the BOINC client will connect to the SETI@Home server and download one or more work units, and when the computer is idle will start to analyse the data. There are two different searches that look through the radio signals, looking for evidence of communications from extraterrestrials. Many of the radio waves received will have come from Earth, satellites, galactic noise, and other astronomical phenomena. In the first instance, if a signal is received when the telescope is aimed at a particular point of the sky, the signal is assumed to be interference. Only if the signal repeats several times, and also at different observation times is it considered to be originating in the remote point the telescope is pointing at, rather than interference of some kind.
Another mode of analysis is called Astropulse. Not all computers have the capability of performing this type of analysis, but for those that do, BOINC will automatically download Astropulse work units. This search analyses broadband pulses of radio waves, which are very short-lived. i.e. they last only microseconds.
The SETI@Home project celebrated its tenth anniversary earlier this year (2009). During this time no signal has been found that can be attributed to a signal from extraterrestrial beings. In spite of this the SETI@Home project has been one of the most popular of all the distributed computing initiatives. Currently there are about 183,000 active users. No doubt each of them is hoping that their computer will be the one that finds the first unequivocal signal from an extraterrestrial.
Sources:
Berkeley Open Infrastructure for Network Computing (BOINC)
Arecibo Observatory : http://www.naic.edu
Trevor Lewis - Trevor Lewis has been working in the IT industry for the last thirty years. He also has a long-standing interest in astronomy and space ...
