What is Breakthrough Listen and its current status?

Introduction

The Breakthrough Listen project, a global effort to detect signs of intelligent life beyond Earth, has been scanning the cosmos for technosignatures—evidence of technology created by extraterrestrial civilizations, such as radio waves or laser pulses. Launched in 2015, this initiative uses some of the world’s most advanced telescopes to capture vast datasets from stars, galaxies, and exoplanets. As of July 12, 2025, recent advancements, including a new study targeting 27 eclipsing exoplanets, have expanded the project’s scope and refined its methods. This article explores the latest findings, including the 2025 study accepted for publication in the Publications of the Astronomical Society of Australia.

Expanding the Search with New Telescopes and Partnerships

Breakthrough Listen employs powerful instruments like the Green Bank Telescope in West Virginia, the Parkes Telescope in Australia, and the MeerKAT array in South Africa. In 2024, the project partnered with the Westerbork Observatory in the Netherlands, collaborating with ASTRON and the University of Manchester. This partnership introduced an all-sky monitor, enabling continuous observation of the entire visible sky for transient radio signals, which could indicate brief bursts from extraterrestrial technology.

The Sardinia Radio Telescope in Italy joined the effort, enhancing the project’s ability to detect faint signals across a wider frequency range. The FAST telescope in China has also been integrated, allowing exploration of higher frequencies up to 93 GHz. These additions improve the project’s sensitivity to weak or short-lived signals, such as laser pulses or intermittent radio emissions, that earlier surveys might have missed. The VERITAS observatory in Arizona continues to support optical searches, targeting laser signals that advanced civilizations might use for communication or propulsion.

These new facilities complement the project’s core strategy of scanning one million nearby stars, the Milky Way center, and 100 neighboring galaxies. The expanded telescope network allows Breakthrough Listen to cover more sky and frequencies, increasing the odds of detecting a signal that stands out from cosmic noise.

Recent Observations and Signal Analysis

In 2024, a student-led study published in Nature Astronomy used machine learning to analyze MeerKAT data, identifying several signals with unusual characteristics, such as narrow bandwidths or frequency drifts. These signals, observed while targeting one million nearby stars, were intriguing because they matched some expected traits of technosignatures. However, after extensive analysis, most were attributed to natural astrophysical phenomena, like pulsars, or terrestrial interference from satellites or radio equipment. This study showcased the power of artificial intelligence in processing vast datasets, enabling researchers to quickly flag potential signals for further scrutiny.

Another effort mined the MeerKAT archive for transient radio sources, in collaboration with the Rhodes Centre for Radio Astronomy Techniques and Technologies, Observatoire Paris Meudon, and the University of Oxford. This project uncovered previously undetected short-duration signals, some lasting only seconds. While none were confirmed as extraterrestrial, the work improved methods for detecting fleeting events, which could be critical for identifying signals from orbiting spacecraft or planetary transmitters.

The BLC1 signal, detected in 2020 near Proxima Centauri, was revisited in 2025 with higher-resolution data from the Green Bank Telescope and MeerKAT. The analysis confirmed that BLC1 likely originated from Earth-based interference, possibly from a nearby radio source. This finding, while ruling out an extraterrestrial origin, strengthened the project’s data pipeline by refining algorithms to filter out human-made noise, ensuring future signals are better scrutinized.

Targeting Eclipsing Exoplanets: The 2025 Study

A significant milestone came in 2025 with a study published in the Publications of the Astronomical Society of Australia. This research, conducted by a team from the University of Southern Queensland and the SETI Institute, focused on 27 eclipsing exoplanets selected from the Transiting Exoplanet Survey Satellite (TESS) catalog. Eclipsing exoplanets are those that pass behind their host stars during their orbits, creating opportunities to detect signals that might be interrupted by these events, a phenomenon known as occultation.

The study targeted these exoplanets because their predictable transits allow researchers to time observations precisely, looking for signals that disappear when the planet is obscured by its star. This approach is innovative because it could reveal technosignatures from transmitters on or near the exoplanet, such as satellites or surface-based technology, by observing signal interruptions. The team used the Parkes Telescope’s Ultra-Wideband Low (UWL) receiver, which records two polarizations of radio signals, represented as red and blue in spectral diagrams, to capture data across a wide frequency range.

The researchers analyzed 3.6 million high-frequency resolution ($2.4 , \text{Hz}$) data files using the turboSETI pipeline, a Python-based tool designed to detect narrowband signals with Doppler drifts—frequency shifts caused by the motion of a source relative to Earth. The study cross-referenced TESS targets with the Parkes Telescope’s observing catalog, focusing on 27 systems with confirmed transiting exoplanets. Observations were timed to coincide with secondary transits, when the planet passes behind its star, to detect any signal drop-offs that might indicate a planetary transmitter.

No definitive technosignatures were found, but the study identified several candidate signals with varying drift rates. These signals were visualized in diagrams showing their frequency behavior, with some aligning briefly with predicted drift rates for the target exoplanets. However, further analysis suggested these were likely caused by local radio frequency interference (RFI), such as from Earth-based sources, which consistently affect the UWL bandpass. The study’s findings were significant not for confirming extraterrestrial signals but for demonstrating a novel method of using occultation to search for technosignatures, paving the way for future targeted observations.

This study’s approach, focusing on occultation events, offers a new lens for the search, as it leverages the unique geometry of eclipsing systems to differentiate planetary signals from stellar or background noise. The lack of confirmed signals doesn’t diminish the study’s value; it establishes a framework for future searches, particularly for systems with short orbital periods, like WASP-12b, which orbits its star in just over one day.

Collaboration with TESS and Exoplanet Focus

The partnership with TESS, ongoing since 2019, remains a cornerstone of Breakthrough Listen’s strategy. TESS identifies exoplanets by detecting dips in starlight as planets transit their stars. By July 2025, TESS had confirmed over 1,500 exoplanets, many in habitable zones where liquid water could exist. The 2025 study built on this by selecting 27 eclipsing exoplanets from the TESS catalog, but the broader collaboration has integrated hundreds of TESS targets into Breakthrough Listen’s observation schedule.

The Allen Telescope Array and the Automated Planet Finder at Lick Observatory scan these targets for radio and optical signals. The focus on habitable-zone planets, like those around Sun-like stars, increases the chances of detecting signals from environments suitable for life. The 2025 study’s emphasis on eclipsing systems adds a layer of precision, as it uses the timing of transits to search for signal interruptions, a method that could reveal technology on or near exoplanets.

Technological Advancements and AI Integration

Breakthrough Listen handles an immense data volume, with the Green Bank Telescope capturing 24 gigabytes per second across a 6 GHz bandwidth. In 2025, the project upgraded its computing cluster to 128 GPUs, enabling faster processing of petabytes of data annually. Machine learning models, like those used in the 2024 Nature Astronomy study and the 2025 exoplanet study, detect patterns such as Doppler-shifted signals, which indicate motion relative to Earth. These models analyze data in real time, flagging anomalies for human review.

The turboSETI pipeline, used in the 2025 study, is publicly available on GitHub, allowing researchers and citizen scientists to search for narrowband signals in archived data. The Breakthrough Initiatives Open Data Archive hosts petabytes of observations, fostering global collaboration. While SETI@home ended in 2020, new crowdsourcing platforms launched in 2025 engage volunteers in analyzing MeerKAT and Parkes data, keeping public participation central to the project.

The challenge of radio frequency interference (RFI) remains significant. The 2025 study noted that local RFI sources, like satellites or ground-based equipment, often mimic technosignatures. Advanced algorithms now filter these out by identifying patterns inconsistent with cosmic sources, such as signals that persist across multiple observations without Doppler shifts. This was critical in ruling out candidates in the exoplanet study, ensuring only genuine signals are pursued.

What the Results Mean for the Search

The absence of confirmed technosignatures in the 2025 study and earlier efforts doesn’t indicate failure. Each observation refines the search, ruling out frequency bands, star systems, or signal types, which narrows future targets. The 2025 study’s focus on eclipsing exoplanets introduced a novel method, using occultation to detect planetary transmitters, which could guide future searches toward systems with similar orbital dynamics.

Non-detections also improve technology and analysis pipelines. The BLC1 analysis, the 2024 MeerKAT study, and the 2025 exoplanet study have honed algorithms to better distinguish signals from noise. The open-data approach invites global scrutiny, with citizen scientists and researchers worldwide contributing to the effort. This collaborative model ensures diverse perspectives and accelerates data analysis, increasing the likelihood of spotting a genuine signal.

The 2025 study’s findings, while not confirming extraterrestrial signals, highlight the potential of targeting eclipsing systems. By observing signal drop-offs during transits, researchers can focus on planets with short orbital periods, which are more likely to yield detectable signals due to frequent eclipses. This method could be scaled to hundreds of TESS-identified exoplanets, expanding the search’s precision.

Looking to the Future

Breakthrough Listen plans to upgrade the Green Bank Telescope’s data recorder to capture a 12 GHz bandwidth, doubling its current capacity. The Jodrell Bank Observatory and e-MERLIN will join the telescope network, enhancing coverage of radio and optical signals. The VERITAS observatory will expand its role in detecting laser pulses, which could indicate advanced communication or propulsion systems.

The project is exploring new frequency ranges, including microwave and infrared spectra, to cover potential communication modes of extraterrestrial civilizations. Future studies will build on the 2025 exoplanet research, targeting more TESS-identified systems with eclipsing orbits. The integration of AI will continue to evolve, with plans to develop even more sophisticated models to detect complex signal patterns, such as those modulated by planetary atmospheres or orbital dynamics.

Public engagement will remain a priority. New platforms for crowdsourcing data analysis are being developed, building on the legacy of SETI@home. The open-data archive will expand, with regular releases of new observations from MeerKAT, Parkes, and FAST, inviting global participation in the search for life.

Summary

As of July 2025, Breakthrough Listen continues to lead the search for extraterrestrial intelligence, with recent advancements including new telescopes like Westerbork and Sardinia, AI-driven signal detection, and a groundbreaking 2025 study targeting 27 eclipsing exoplanets from the TESS catalog. While no technosignatures have been confirmed, the project’s findings, from the BLC1 analysis to the exoplanet study’s novel occultation method, have refined detection techniques and expanded the search’s scope. By leveraging partnerships with TESS, advanced computing, and public collaboration, Breakthrough Listen is pushing the boundaries of what’s possible, bringing humanity closer to answering whether we’re alone in the universe.