Airport radar signals could reveal Earth’s presence to alien civilizations, study suggests

Radar systems operating at airports around the world may be unintentionally broadcasting evidence of human civilization

Radar systems operating at airports around the world may be unintentionally broadcasting evidence of human civilization into deep space, according to a 2025 study conducted by researchers at the University of Manchester. The findings suggest that the combined radio emissions produced by civilian and military radar networks could be detectable by technologically advanced extraterrestrial civilizations located within hundreds of light-years of Earth.

The study found that radar systems at major civilian airports generate a combined signal of approximately 2 × 10¹⁵ watts. According to the researchers, this level of radio emission is powerful enough to be detected from as far as 200 light-years away by a radio telescope with sensitivity comparable to the Green Bank Telescope in West Virginia, one of the world’s largest fully steerable radio observatories.

The research was led by Ramiro Caisse Saide, with contributions from Professor Michael Garrett and other members of the University of Manchester team. The scientists developed computer models to track how radar signals from some of the world’s busiest airports—including London Heathrow, London Gatwick, and New York’s John F. Kennedy International Airport (JFK)—spread through space over time.

To better understand how these emissions might appear to distant observers, the team simulated the signals from the perspective of nearby star systems, including Barnard’s Starand AU Microscopii. Their analysis showed that the radio waves produced by Earth’s aviation infrastructure would appear as clear signs of advanced technology to anyone equipped with sufficiently powerful radio telescopes.

The researchers also examined military radar systems, which emit radio waves in a much narrower and more focused beam than civilian airport radar. These systems produce peak emissions of around 1 × 10¹⁴ watts. Although their total power output is lower than the combined emissions from civilian airports, their highly directional nature makes them particularly noticeable across interstellar distances.

According to Caisse Saide, these concentrated military radar signals would almost certainly appear artificial to any technologically advanced civilization monitoring radio emissions from space. He explained that the directed beams could appear up to 100 times stronger than the more widely dispersed signals produced by civilian radar systems, making them even easier to distinguish from naturally occurring radio sources.

One reason the researchers focused on Barnard’s Star is the presence of a rocky exoplanet known as Barnard b, which orbits the nearby star. The team noted that if intelligent life exists on such worlds, any radio leakage from their technology would be the type of signal scientists on Earth hope to detect while searching for technosignatures—evidence of advanced civilizations beyond our solar system.

Professor Garrett said the research has practical benefits beyond the search for extraterrestrial intelligence. The modelling techniques developed for the study could help engineers improve radar system designs, better manage the radio frequency spectrum used for communications, and reduce unnecessary signal interference.

Caisse Saide added that the same methods could also contribute to planetary defence efforts and help scientists better understand how human technology influences Earth’s surrounding space environment. The study highlights that everyday technologies, designed for aviation and national security, may also serve as unintentional beacons announcing humanity’s presence to the wider galaxy.