The SETI@home project – short for Search for Extraterrestrial Intelligence – ran from 1999 to 2020 and relied on volunteers’ home computers to process radio signals from space. Over 12 billion potential signals were collected during this project. The SETI@home team spent 10 years analyzing these signals, narrowing them down to about a million before coming up with a final list of 100 radio signals that now require a deeper look.
All of this may come to nothing, but that doesn’t mean SETI hasn’t made any major steps forward as a result of this ambitious project.
“If we don’t find ET, we can say we have established a new sensitivity level. If there was a signal above a certain strength, we would have found it,” computer scientist and SETI@home co-founder David Anderson said in a statement. The results of the project have been published in two papers in The Astronomical Journal.
home phone
The project asked volunteers to install software on their home computers, allowing the team to analyze data collected by the now-closed Arecibo Observatory in Puerto Rico in search of unusual radio signals.
Over a period of 21 years, millions of people from around the world signed up to help search for alien signals. “When we were designing SETI@home, we tried to decide whether it was worth doing, whether we would get enough computing power to actually do new science,” Anderson said. “Our calculations were based on getting 50,000 volunteers. Very quickly, we had a million volunteers. That was great, and I would like to tell that community and the world that we really did some science.”
The idea was to break large amounts of data – usually processed by supercomputers – into smaller pieces that could be handled by multiple home computers. The data were passively recorded as astronomers pointed Arecibo’s radio dish at different areas of the sky and then distributed to various home computers.
The SETI@home software will then manipulate the data using a mathematical tool known as the discrete Fourier transform, which shows which frequencies make up the radio signal. The software scanned the data for changes in frequency depending on the relative motion of the source, a phenomenon known as Doppler drift.
signal interference
The project initially generated 12 million signals, but the scientists behind the project had to figure out a way to reduce them. “Up until about 2016, we didn’t really know what we were going to do with these discoveries,” Anderson said. “We didn’t understand how to do the whole second part of the analysis.”
The team used a supercomputer provided by the Max Planck Institute for Gravitational Physics in Hanover, Germany, to eliminate radio frequency interference and noise. This limited the number of signals to a few million, and they were examined once again to eliminate signals coming from the same location in the sky or on the same frequency.
The final thousand signals had to be evaluated manually, and the team came up with a final 100 candidates that were deemed worthy of further investigation. “There is no way you can fully investigate every possible signal detected, because doing so still requires a person and eyeballs,” astronomer and SETI@home project director Eric Korpela said in a statement. “We have to do a better job of measuring what we’re throwing out. Are we throwing the baby out with the bathwater? I don’t think we know that for most SETI searches, and this is really a lesson for SETI searches everywhere.”
The final analysis of the project is yet to come.
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