A long-defunct NASA communications satellite has unexpectedly emitted a powerful pulse of radio waves, providing a rare glimpse into how abandoned spacecraft can still affect observations from Earth. Relay 2, launched in 1964 and declared inoperative in 1967, produced a burst that momentarily outshone every other radio source in the sky, according to a peer-reviewed study released this week in The Astrophysical Journal Letters. Astronomers using the Australian Square Kilometre Array Pathfinder (ASKAP) detected the flash on 13 June 2024 while searching for fast radio bursts. The signal, lasting less than 30 nanoseconds, came from roughly 4,500 kilometres above Earth—well within the near-field range of the telescope. Lead author Clancy James of Curtin University said the pulse was “incredibly powerful,” measuring some 2,000 to 3,000 times brighter than the instrument’s typical sky background. Because Relay 2 has no functioning transmitters, researchers conclude the emission was most likely triggered by an electrostatic discharge that built up on the satellite’s metal skin, although a high-velocity micrometeorite strike generating a plasma cloud remains a secondary possibility. Either scenario highlights physical processes that modern spacecraft designs strive to mitigate but that were not considered when early satellites were built. The event underscores a growing concern that radio emissions from aging space debris could masquerade as astrophysical phenomena, complicating efforts to study the cosmos. More than half of the roughly 22,000 satellites ever launched are now inactive, and scientists say monitoring their occasional radio outbursts could become an important tool—both for safeguarding orbital assets and for keeping Earth-based radio astronomy free from inadvertent interference.