SETI@home's 21-Year Hunt Reveals 100 Unexplained Signals from Space

For over two decades, the SETI@home project harnessed the power of millions of computers worldwide to search for signs of extraterrestrial intelligence. After analysing more than 12 billion radio signals from the Arecibo Observatory, researchers narrowed down 100 potential candidates that could not be easily explained by natural or human-made sources. While none have yet proven to be a definitive alien message, the effort has set new standards for future searches.

SETI@home launched in 1999 as a citizen science initiative, allowing volunteers to donate spare computing power to process vast amounts of radio telescope data. Over 21 years, the project scrutinised signals collected by the Arecibo Observatory, filtering out interference and known terrestrial sources. Despite the enormous dataset, only 100 signals remained unexplained after rigorous analysis.

The project did not disclose how many of the original 12 billion signals were ruled out or the exact methods used to distinguish them. However, it highlighted the need for more refined algorithms to avoid accidentally discarding potential extraterrestrial signals. Researchers also noted that the raw data might still contain overlooked candidates, requiring further examination.

Today, China's FAST radio telescope is being used to follow up on the 100 signal candidates. Scientists are focusing on stars with known exoplanets, as these systems are considered prime targets for deeper investigation. While none of the signals have matched the significance of the famous 'Wow! signal' from 1977, the project has improved detection sensitivity and optimised techniques for future searches.

The SETI@home project concluded without confirming extraterrestrial contact, but its legacy continues to shape the search for alien technosignatures. The 100 unexplained signals remain under observation, with advanced telescopes like FAST providing new opportunities for analysis. The work has also established a framework for more precise and efficient searches in the years ahead.