A new study by the SETI Institute has found that stellar "space weather" could make radio signals from extraterrestrial intelligence more difficult to detect by altering them before they leave their home planetary systems.
The research suggests that stellar activity and plasma turbulence near a transmitting planet can broaden extremely narrow radio signals, spreading their power across a wider range of frequencies and reducing their visibility in conventional technosignature searches.
Challenge to traditional SETI searches
For decades, many SETI efforts have focused on identifying narrow spikes in frequency, which are considered unlikely to arise from natural astrophysical processes.
However, the new study indicates that even a perfectly narrow signal generated by an extraterrestrial transmitter may become distorted before it exits its own star system.
While scientists have traditionally accounted for signal distortions that occur during travel through interstellar space, the research highlights effects that can take place much closer to the source. According to the study, fluctuations in plasma density within stellar winds, along with eruptive events such as coronal mass ejections, can alter radio waves and spread their frequency range. This process weakens the peak signal strength relied upon by existing search methods.
Researchers examine impact of stellar environments
Lead author Vishal Gajjar said SETI searches are often designed to detect extremely narrow signals. He noted that if a signal is broadened by conditions surrounding its host star, it may fall below detection thresholds even if it is present, potentially contributing to the lack of confirmed technosignatures.
To measure the effect, researchers used radio transmissions from spacecraft within the solar system. Drawing on empirical observations from space probes, the team calibrated how turbulent plasma affects narrowband signals and then extended those findings to a variety of stellar environments.
The study produced a framework for estimating the extent of signal broadening across different star types and observing frequencies, particularly under the space weather conditions associated with highly active stars.
M-dwarf stars identified as a key concern
The findings suggest important implications for future target selection and search strategies. The researchers found that signals originating around M-dwarf stars are especially vulnerable to broadening before leaving their systems.
M-dwarf stars account for approximately 75 per cent of all stars in the Milky Way, making them a significant focus for technosignature searches. The authors argue that future search techniques should remain capable of detecting signals even when they are no longer perfectly narrow.
Co-author Grayce C. Brown said that understanding how stellar activity alters narrowband transmissions could help scientists develop search methods that better reflect the signals that actually reach Earth rather than those originally transmitted.
Disclaimer: This report is based on information and statements released by the SETI Institute. ET.com has rewritten the material for news reporting purposes and does not independently verify or endorse the research findings, interpretations or conclusions presented in the study. All credit for the research, data, analysis and statements belongs to the SETI Institute and the study's authors.
