In June 2024, astronomers detected a strange, extremely powerful burst of radio waves coming not from a distant galaxy, but from within our own Milky Way. Even more surprisingly, the source may have been a long-inactive NASA satellite, Relay 2, which launched in 1964 and went offline in 1967. The event, recorded by the Australian Square Kilometer Array Pathfinder (ASKAP), lasted just 30 nanoseconds yet briefly outshone everything else in the radio sky.
Clancy James, a radio astronomer at Curtin University in Australia, led the research, which was published in a preprint study on arXiv. He described the signal as a dramatic spike, unlike anything typically seen, so intense and brief that ASKAP had trouble focusing on it, much like how a camera lens struggles to capture an object that’s too close.
Initially, the team thought they had discovered an entirely new cosmic phenomenon, possibly a pulsar or an exotic star. However, after carefully tracing the source of the pulse, they found that only one object was located in that region of space: Relay 2. This old satellite, which had been silent for almost 60 years, suddenly appeared to emit a brief yet massive burst of radio energy. Given that the signal didn’t match any system or transmitter onboard the spacecraft, it couldn’t have been intentional or the result of a software glitch. That left the researchers with two plausible explanations.
The first is that the satellite was struck by a micrometeoroid. Such high-speed impacts in space can produce plasma clouds and electromagnetic disturbances that might briefly radiate energy in the form of radio waves. These impacts could temporarily alter the local space environment around a satellite and trigger strong emissions.
The second and more likely cause, according to the researchers, is an electrostatic discharge. Over decades in orbit, Relay 2 may have built up electrical charge across different parts of its structure, eventually releasing it in a sudden, powerful arc. This kind of discharge is well known to create radio pulses and is especially plausible given that Relay 2 was made of early-generation spacecraft materials capable of holding significant charge.
Though scientists may never know for sure whether the cause was a micrometeorite or an electrical arc, the incident is significant. Karen Aplin, a professor of space science at the University of Bristol, believes this finding could pave the way for new methods of detecting and analyzing electrostatic discharge events in space. As modern satellite constellations expand, often with low-cost spacecraft that lack robust shielding, such knowledge could help mitigate failures and better track space weather effects on aging or vulnerable hardware.