Recently, a team of astronomers and astrophysicists from multiple Australian institutions made an unexpected discovery. A mysterious fast radio burst (FRB) detected last year did not originate from the distant depths of the universe but from a defunct satellite orbiting Earth—NASA's Relay 2. The team has published a paper on the arXiv preprint server detailing this finding.

On June 13, 2024, the Australian Square Kilometre Array Pathfinder (ASKAP) telescope team captured a potential fast radio burst lasting less than 30 nanoseconds. The pulse signal was exceptionally strong, even overpowering all other signals from the sky. Initially, the research team assumed the signal came from some distant cosmic object, as most fast radio bursts exhibit this characteristic. However, subsequent in-depth analysis revealed the true source of the signal.

Further investigation confirmed that the signal originated from the Relay 2 satellite. Launched in 1964, this experimental communications satellite ceased operations after less than a year and its transponder stopped responding in 1967. The research team found that the defunct satellite was passing directly overhead when the fast radio burst occurred, producing such a strong and clear signal.

Regarding the cause of the signal, the research team proposed two possibilities. One is the release of electrostatic charge accumulated on the satellite to a certain extent, a discharge phenomenon that has been recorded before. The other is that the satellite was struck by a micrometeoroid, releasing a small cloud of plasma.

This discovery not only reveals another possible source of fast radio bursts but may also provide inspiration for developing new tools to study space signals. At the same time, it could lead to new methods for monitoring the motion of defunct satellites, which is of great significance for space debris management and satellite maintenance.